8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Plenary
INTERPRETING MARKER-BASED POPULATION CONNECTIVITY ESTIMATES
FOR RESTORATION AND MANAGEMENT GOALS
Matthew P. Hare
Department of Natural Resources, 208 Fernow Hall, Cornell University, Ithaca, NY 14853, USA; email:
mph75@cornell.edu
Because species-specific larval behaviors can dramatically alter expectations for average
dispersal distance, measuring realized population connectivity has been an important and
challenging goal for the management of marine species. It is widely recognized that genetic
markers, when analyzed and interpreted in terms of equilibrium theory, provide estimates of
long-term realized population connectivity. Convincing managers that such estimates are
relevant to ecological-scale goals can be challenging. I will present genetic data bearing on
larval dispersal in the eastern oyster, Crassostrea virginica, and use several approaches to
verify their relevance to contemporary processes at ecological time scales. Simulations will be
used to explore what demographic conditions (effective population size, proportion of
migrants) are incompatible with population genetic results and to test whether one century of
overfishing and management could bias equilibrium evolutionary inferences. Additional
perspective will be derived from comparisons with biophysical larval dispersal models and
nonequilibrium genetic analyses.
LESSONS FROM A CLOSET OTOLITH CHEMIST: USING GEOCHEMICAL
APPROACHES TO INVESTIGATE LARVAL DISPERSAL IN INVERTEBRATES
AND FISH
Stephen E. Swearer
Department of Zoology, University of Melbourne, 3010 VIC Australia; email: sswearer@unimelb.edu.au
Although the first geochemical analysis of calcified structures in a larva was published over
20 years ago, the field of larval carbonate geochemistry is still in its infancy, particularly with
regards to larval dispersal studies. In this talk I will present an overview of the basic
principles of geochemical analysis and how they have been applied to investigate larval
dispersal in invertebrates and fish. Using examples from my own research and others, I will:
(1) review some of the methodological advances, such as atlases of natal geochemical
signatures and transgenerational isotopic labeling, that have occurred in the past several years,
(2) highlight some of the often unaddressed challenges and pitfalls associated with sample
analysis and data interpretation, and (3) conclude with several key issues which require
resolution to improve the utility of these approaches in investigations of larval dispersal.
8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Oral
IDENTIFYING SOURCES OF REPLENISHMENT IN POPULATIONS
DIADROMOUS GALAXIIDS IN SOUTHEASTERN AUSTRALIA
OF
Nicole C. Barbee and Stephen E. Swearer
Department of Zoology, University of Melbourne, Parkville, Victoria 3010 Australia; email of presenting author:
nbarbee@unimelb.edu.au
For species with a highly dispersive larval stage, understanding how populations are
maintained is dependent on knowledge of the frequency and scales over which dispersal
occurs. The diadromous galaxiid, Galaxias maculatus (Galaxidae), is one of the most
widespread freshwater fishes in the world, with a distribution that includes New Zealand,
southeastern Australia and the southern tip of South America. The protracted marine larval
phase of this species likely contributes to its broad distribution, however little is known of the
demographically relevant scales of dispersal among riverine populations. We are using natural
environmental signatures in otoliths to determine the degree of connectivity among
populations of G. maculatus in rivers in southeastern Australia. Using LA-ICPMS, we
analysed otoliths from G. maculatus hatchlings from sites across coastal Victoria, Australia to
characterise the elemental signatures of fish from known locations. We then examined the
otoliths of recruiting larvae and compared them to the signatures of hatchlings from known
sites to identify the original source population of recruits and hence how far they had
dispersed. Recruit otoliths were also used to examine and compare the environmental
histories experienced by larvae during the marine pelagic stage. Our results suggest that
dispersal from both near and far way sources are important to the maintenance of galaxiid
populations.
THE POPULATION CONNECTIVITY OF THE OLYMPIA OYSTER (OSTREA
CONCHAPHILA) WITHIN AND AMONG SOUTHERN CALIFORNIA ESTUARIES,
DETERMINED USING TRACE-ELEMENTAL FINGERPRINTING OF THE
LARVAL SHELL
Henry S. Carson
San Diego State University and University of California, Davis 5500 Campanile Dr., San Diego, CA 92182
USA; email: hcarson@mail.sdsu.edu
If information about the chemical conditions of origin is preserved in the calcified structures
of larval marine animals, this information can potentially be accessed and used as a
“fingerprint” to determine the location of origin for settling larvae. Tracking the larval
dispersal of marine animals in this way can provide estimates of population connectivity and
inform the management of threatened or commercially important species, marine reserves,
and exotic invasions. The Olympia Oyster (Ostrea conchaphila) is a potentially useful model
species to study larval dispersal using trace elemental fingerprinting because brooded larvae
begin to form their shell before departing on their planktonic journey. Late-stage O.
conchaphila larvae were periodically removed from adults at eight sites in four southern
California estuaries in the summers of 2006 and 2007. Their larval shells were analyzed using
8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Oral
laser ablation inductively-coupled plasma mass spectrometry (ICP-MS) to determine the
concentrations of 12 elements. The ratios to Calcium of Manganese, Copper, Zinc, Barium,
Lead and Uranium were used to distinguish between populations in a discriminant function
analysis. The accuracy of assignment was maximized by grouping the eight sites into three
regions. Settlement plates were deployed at each of the sites to collect recent O. conchaphila
settlers of unknown origin. The portion of each settler’s shell formed during brooding was
analyzed using laser ablation ICP-MS, and the information used to assign each settler to one
of the defined regions or to an unknown source. The elements and concentrations that made
up distinct regional chemical fingerprints varied by year and month, and were not always
clearly linked to observed temperature or sampled seawater chemistry. These results
demonstrate that larvae of O. conchaphila can be tracked using trace elemental fingerprinting,
however the nature of the fingerprint is not temporally stable.
MOLECULAR DETECTION OF NATIVE AND INVASIVE INVERTEBRATE
LARVAE FROM BALLAST AND OPEN WATERS
Julio B. J. Harvey1, Rusty J. Rodriguez2 and Marshall S. Hoy 3
1
7700 Sandholt Road, Moss Landing, CA 95039, USA; email of presenting author: jharvey@mbari.org
University of Washington Department of Biology, Box 351800, Seattle, WA 98195, USA
3
USGS Western Fisheries Research Center, 6505 NE 65th St, Seattle, WA 98115, USA
2
Marine species are transported to non-native environments by a variety of vectors including
ship ballast water. Some alien species become invasive and negatively impact native species
or near shore habitats. Tracking the microscopic dispersal stages produced by broadcast
spawners and identifying these propagules from environmental samples are methods of great
utility in the study of population genetics, dispersal dynamics, recruitment and competition
among marine species. To better manage and protect regionally unique marine habitats, direct
methods for accurately monitoring the dispersal of marine species propagules are required.
We developed molecular markers and a DNA beacon microarray assays to assess ship ballast
and plankton-net tow samples collected from Puget Sound, Washington, for the presence of
native and non-native bivalves, crustaceans and algae. The latter were collected as adults,
identified to morphological species and the intergenic spacer regions (IGS; ITS1, ITS2, 5.8S)
of the nuclear ribosomal DNA were sequenced. We then designed species- or genus-specific
markers and used them to design PCR primers and ultimately, fluorescently labeled molecular
beacons for incorporation into a microarray. The resulting microarray was used to
simultaneously test samples for the presence or absence of multiple taxa. Problematic
qualities of DNA beacons include a limited ability to accurately differentiate among complex
mixtures of organisms found in some environmental samples. Using peptide nucleic acid
(PNA) beacons might solve this problem because they reportedly exhibit greater target
detection stringency. Alternatively, the sensitive and robust rRNA targeted sandwich
hybridization assay (SHA) has been shown to perform well for marine larval detection and
enumeration in the Monterey Bay National Marine Sanctuary, California. The results and
limitations of our DNA beacon microarray trails are discussed with respect to these other
promising technologies.
8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Oral
TITLE: RAPID IDENTIFICATION AND SORTING OF MARINE LARVAE USING
FLUORESCENCE IN SITU HYBRIDIZATION AND A LARGE-PARTICLE CELL
SORTER
Christine M. Henzler, Elizabeth A. Hoaglund and Steven D. Gaines
Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA 93106 USA; email of
presenting author: henzler@msi.ucsb.edu
Pelagic larvae play a key role in the life history of marine invertebrates, but are notoriously
hard to study in the field. Due to their small size and low densities, larvae must be
concentrated by plankton tows or traps, then laboriously sorted and identified in order to
investigate even basic questions about larval abundance, diversity and distribution in the
water column. Additionally, larvae of closely related species are often very similar, and
difficult or impossible to distinguish morphologically. PCR-based genetic techniques can be
used to differentiate morphologically similar species, but, while effective, these methods add
additional time to an already slow process. Another technique, fluorescence in situ
hybridization (FISH), has proven successful as an alternative method for fast identification of
marine plankton to species, genus or family level groups. We demonstrate a novel adaptation
of FISH in conjunction with sorting by a large-particle cell sorter to quickly identify several
species and genera of marine invertebrate larvae. Currently, we have had success identifying
and counting urchin and mussel larvae, and sorting them by type for further analyses. The
method can be easily extended to other taxa, as well. We demonstrate the potential of this
method for decreasing the amount of time required for plankton sample sorting and
identification, and for processing larvae for downstream applications, including genetic
analyses of individual larvae.
AUTONOMOUS UNDERWATER VEHICLES EXAMINE
BETWEEN MARINE LARVAE AND THE COASTAL OCEAN
RELATIONSHIPS
Shannon B. Johnson, Alana Sherman, Roman Marin, John Ryan, and Robert C.
Vrijenhoek
Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, USA; email of presenting author:
sjohnson@mbari.org
The Monterey Bay Aquarium Research Institute (MBARI) routinely operates autonomous
underwater vehicles (AUVs) to map the ocean environment, from the surface to the sea floor.
These AUVs have recently been augmented with artificial intelligence and water sampling
capabilities. The "Gulper" is a water-sampling payload mounted in the mid-body of an AUV
and is comprised of ten 2-liter bottles, each of which can be individually triggered to fill in
two seconds. We conducted mapping and "Gulper" surveys in Monterey Bay, California, to
examine distributions of marine larvae relative to coastal ocean features including an
estuarine plume, the shallow thermocline on the inner northern shelf, and layers of turbid
waters that emanate from the benthos (intermediate nepheloid layers, INLs). Marine
invertebrate larvae were detected with sandwich hybridization assays (SHA) that targeted 18S
8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Oral
ribosomal RNA in all the AUV samples. Molecular probes used in SHA targeted common
Monterey Bay taxa, including mussels of the genus Mytilus, crustaceans, polychaetes, and the
invasive green crab, Carcinus maenas, now common in Elkhorn Slough, the source of the
estuarine plume. Crustaceans and mussels were detected in all assays. Polychaetes were
detected in the INL and in the plume. In the high-resolution inner shelf survey, polychaetes
and mussels were detected only in the thermocline, not in the surface mixed layer. Green
crabs were not detected in any of these surveys. Lysates retained from SHA were further
examined by sequencing five different gene loci. Various decapod crustaceans, polychaete
worms, and gastropod mollusks were identified. Amplifications also illuminated the presence
of marine α-proteobacteria, diatoms, green microalgae, red algae, sponges, and cnidarians.
The ability of the Gulper AUV to identify and sample discrete water layers, such as the INL
and coastal ocean features introduces a novel approach to studying larval ecology and
transport mechanisms.
EXPLORING THE USE OF STATOLITHS AS NATURAL TAGS TO ESTIMATE
POPULATION CONNECTIVITY ACROSS A SPECIES’ RANGE
Sara E. Koch1, Georges L. Paradis1, Steven D. Gaines2, Robert R. Warner2 and Danielle
C. Zacherl3
1
Marine Science Institute, University of California Santa Barbara, California 93106, USA; email of presenting
author: koch@msi.ucsb.edu
2
Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California
93106, USA
3
Department of Biological Science, PO Box 6850, California State University Fullerton, California 92834-6850,
USA
Elements incorporated into larval calcified structures have been used as natural tags to
estimate levels of population connectivity via larval dispersal at various spatial scales, but not
across the entire range of a species. To explore the use of statoliths of Kelletia kelletii as
natural tags, we characterized the scale of spatial variation and temporal stability of
embryonic statolith chemistry at 21 sites across its ~1000 km range (Monterey, California,
USA to Isla Asunción, Baja California, Mexico) in 2004 and 2005. Statoliths were analyzed
for element-to-calcium ratios using laser ablation inductively coupled plasma-mass
spectrometry (LA ICP-MS). Results showed that statolith chemistry was significantly
different among sites and regions. Discriminant function analysis accurately assigned 43% of
statoliths to natal site and grouping sites into three regions increased classification success to
70%. Statolith chemistry was not temporally stable at the site or regional level, driven mainly
by fluctuations in Ce/Pb and Pb/Ca. Thus, pooling statoliths across years decreased the total
classification success to 63%. Comparing statolith chemistry to collection site temperature
revealed a positive relationship for Mg/Ca and a negative relationship for Sr/Ca, Ba/Ca and
Pb/Ca; these results are generally consistent with findings from laboratory culturing
experiments. Results from this study suggest that natural tags in statoliths K. kelletii can be
used to estimate population connectivity across a species’ range. However, incorporating data
from genetics and oceanographic models would improve estimates. Integrating these
approaches could allow us to test hypotheses about exchange of larvae across the
8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Oral
biogeographic boundary, Point Conception, California, and between California, USA and
Baja California, Mexico.
CONNECTIVITY METRICS FOR MUSSELS: INTEGRATING
APPROACHES TO THE STUDY OF LARVAL CONNECTIVITY
MULTIPLE
Lisa Levin1, Linda Rasmussen1, Pat McMillan1, Bonnie Becker2, Kristen Gruenthal3 and
F. Joel Fodrie4
1
Integrative Oceanography Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0218 USA;
email of presenting author: llevin@ucsd.edu
2
Interdisciplinary Arts and Sciences, University of Washington, 1900 Commerce St. Tacoma, WA 98402-3100
USA
3
Hubbs-SeaWorld Research Institute, 2595 Ingraham St., San Diego, CA 92109 USA
4
Dauphin Island Sea Laboratory, 101 Bienville Blvd. Dauphin Island, Alabama 36528. USA
Knowledge of larval connectivity patterns and their variation in space and time can provide
tremendous conservation and resource management benefits, and will advance the science of
ecology and evolution. Approaches to determining larval connectivity of bivalves include
applications of shell microchemistry and numerical simulations of larval transport. We
applied trace elemental fingerprinting to the study of larval connectivity of the mussels
Mytilus californianus and Mytilus galloprovincialis, using outplanted larvae to obtain
elemental reference signatures for larval shells in different water masses. Origins of newly
settled recruits were assigned based on the chemical signatures of their retained larval shells.
Results from numerous sites in southern California for two species in two years revealed high
variability in connectivity among sites and between species and years. These results were
compared to connectivity predictions generated by real time numerical simulations using a
nested 3-D ROMS coastal circulation model. In many instances the model predictions
contrasted greatly with the fingerprinting results, but comparisons did reveal key influences
on larval connectivity in San Diego County. These include relative larval supply at spawning
sites, spawning times, vertical position of larvae in the water, planktonic duration, and remote
wind forcing. Quantitative metrics are developed to compare connectivity patterns across
sites, species, years, and assessment methods. Using similarity and diversity indices as well as
connectivity matrix properties we assessed self recruitment, diversity of sources, the influence
of distance on connectivity, and compatibility of trace elemental fingerprinting and numerical
simulations. By combining approaches we gained a more detailed understanding of local
connectivity patterns, their forcing mechanisms, and their spatial and temporal variability.
SHELL BIREFRINGENCE PATTERNS: A METHOD
IDENTIFICATION OF BIVALVE LARVAE IN THE FIELD
FOR
AUTOMATED
Christine M. Mingione and Scott M. Gallager
Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA; email of
presenting author: cmingione@whoi.edu
8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Oral
Field studies of bivalve larval transport and dispersal are often faced with challenges of
accurately identifying larvae to species. Methods currently employed for larval identification,
including visual, molecular, and immunological techniques, often fall short of being
universally feasible due to issues associated with high costs, large efforts, and limited
reliability. Computer-based image identification techniques are routinely employed with
much success in the field of plankton ecology and show promise for use with identifying early
stages of bivalve larvae. Computers can isolate features from unknown images and use these
for classification based on feature data from training sets of known images. Bivalve larval
shells are birefringent and produce distinct color patterns under polarized light, and these
patterns can be used to classify larvae to species with computers. This method has been
successful in classifying six species of larvae grown in monocultures with an accuracy of
90%. Use of this method has much potential for field studies because costs are minimal,
images are processed rapidly, and it can be adapted for use on both live and preserved
specimens. However, using field samples pose new challenges for this method based on
condition of the larval shell, mixtures of unknown species, and morphological differences
associated with different size classes. To account for these issues, we have created a new set
of training images of four commercially important species common to estuarine waters
around Cape Cod, MA that more closely resemble field larvae. We will present classification
accuracy data for this new training set as well as some preliminary species-specific data from
a set of weekly samples taken during the summer spawning period on Cape Cod in 2007. It is
our hope that, once perfected, this method can be adapted for use in other bivalve larval field
studies, both on Cape Cod and elsewhere.
POPULATION GENETICS AND CRAB LARVAL DISPERSION: A CASE OF
STUDY FROM THE EAST AFRICA COAST AND SEYCHELLES ISLANDS
L. Ragionieri, S. Cannicci, G. Cutuli , S. Mannini, M. Vannini and S. Fratini
1
Dipartimento di Biologia Evoluzionistica Leo Pardi, University of Florence, Italy. Via Romana n.17, Cap
50125, Firenze, Italy; email of presenting author: lapo.ragionieri@gmail.com and lapo.ragionieri@unifi.it
In many marine species with pelagic larvae the larval supply is an important aspect of adult
population dynamic. Potentially larvae are able to interconnect separated populations
dispersing over long distances of open sea. But, how really far and where the larvae go is
difficult to investigate by direct methods. Indirect methods, such as estimation of gene flow
and application of genetic isolation by distance models may help in answering these
questions.
A study was performed across several Western Indian Ocean mangroves on a series of cooccurring crab species (Decapoda Brachyura) aimed at investigating the population structure
and dispersal patterns in a comparative way. The five studied species were: Uca inversa, U.
vocans (Ocypodidae), Neosarmatium meinerti (Sesarmidae), Cardisoma carnifex
(Gecarcinidae), and Scylla serrata (Portunidae). The specimens (15/30 per population per
species) were collected in at least six sites from three different countries along the east Africa
coast (Kenya, Tanzania and Mozambique) and from Seychelles. As genetic marker we
sequenced a portion of the mitochondrial gene for the cytochrome b subunit I. Two main
models have been suggested for mangrove crab larval dispersion: the “retention model” in
8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Oral
which larvae are retained within the estuary area, leading to strong population genetic
structure and the “export model” where larvae are released in open oceanic waters and are
able to connect populations.
Our study show that all the species are characterised by high gene flows at least among the
continental populations, but for N. meinerti a clear-cut separation of island populations is
evident.
Overall, our results depict an interesting scenario and they will be discussed in terms of biotic
and abiotic factors that may meet in defining the genetic population structure of co-occurring
species.
LARVAL QUALITY IS A FUNCTION OF DISPERSAL HISTORY AND NOT
SOURCE POPULATIONS: IMPLICATIONS FOR CONNECTIVITY IN A MARINE
METAPOPULATION
Jeffrey S. Shima1 and Stephen E. Swearer2
1
School of Biological Sciences and the Coastal Ecology Lab, PO Box 600, Victoria University of Wellington,
New Zealand; email of presenting author: Jeffrey.Shima@vuw.ac.nz
2
Department of Zoology, University of Melbourne, Victoria 3010 Australia
Variation in the phenotype or “quality” of dispersing individuals can shape colonization
success and thus local dynamics and patterns of connectivity in a metapopulation. In marine
reef systems, larval dispersal typically connects fragmented populations, and larval quality
may be shaped by developmental history at the natal reef (e.g., parental effects) and/or by
conditions in the pelagic environment (e.g., food, temperature, hydrodynamics, predator
regime). We extract information recorded within the incremental bands of fish ‘ear stones’
(otoliths) to reconstruct the early life histories of reef fish, to evaluate whether larval quality is
a function of natal populations, dispersal histories, or both. We sampled sagittal otoliths from
282 common triplefins (Forsterygion lapillum) collected at ~weekly intervals between
December 2003 and March 2004, from three sites within Wellington Harbour (New Zealand)
and three sites along the adjacent Wellington South Coast. We used image analysis to
quantify otolith traits and to reconstruct 5 larval phenotypes (pelagic larval duration, size-athatch, early larval growth, late larval growth, and an instantaneous larval growth rate),
followed by a principal components analysis to derive a composite measure of larval quality.
We used LA-ICPMS to quantify otolith microchemistry, followed by a set of cluster analyses
(based upon 13 statistical descriptors of time series for each of 11 trace elemental ratios) to
identify and characterize two putative natal “source populations” and two putative “larval
dispersal histories”. We evaluated the relationship between larval quality, source populations
and dispersal histories using 2-way ANOVA and determined that larval quality of F. lapillum
is a function of larval dispersal history and not source population identity. Specifically, larvae
of F. lapillum with microchemical signatures consistent with retention and/or entrainment in
the nutrient enriched Wellington Harbour had traits associated with elevated larval quality
(i.e., short pelagic larval durations, small size-at-hatch, fast late larval growth, and fast
instantaneous growth rates). Our results suggest that conditions in the pelagic larval
environment shape larval quality and potentially mediate metapopulation connectivity. In the
case of F. lapillum from Wellington Harbour, environmentally induced heterogeneity in larval
8th Larval Biology Symposium
Lisbon, 2008
Molecular and geochemical markers for assessing
larval dispersal
Oral
quality may limit connectivity by favoring successful replenishment by locally retained larvae
over long-distance dispersers.
THE USE OF GENE MARKERS TO ESTIMATE LARVAL DISPERSAL OF
FARMED COD IN THE NATURAL ENVIRONMENT
Terje van der Meeren, Knut E. Jørstad, Tore S. Kristiansen and Svein Sundby
Institute of Marine Research, Post Box 1870 Nordnes, 5817 Bergen, Norway; email of presenting author:
knut.joerstad@imr.no
In Norwegian seawaters the Atlantic cod (Gadus morhua) is spawning at numerous spawning
sites locations in the coastal and fjord areas along the coast. Especially for the various coastal
cod populations, there are limited knowledge about the dispersal of eggs and larvae from local
spawning areas. Recently, studies have been initiated with genetic marked farmed cod which
will spawn in the net cages, and the main focus is the potential genetic interaction between
farmed and wild cod populations. The farmed cod used was homozygote for a rare allele
(GPI-1*30) in the enzyme glycosephosphate isomerase, and was used during two spawning
seasons (2006; 2007) carried out in a nearly landlocked fjord (Heimarkspollen) in Austevoll at
the west coast of Norway. In both years, the fish were allowed to spawn in net cages from mid
February to mid April. The genetic analyses of collected cod larvae from Heimarkspollen in
late April revealed that 20% (2006) and 35% (2007) of the larvae actually were offspring
from the farmed cod in the net cages. Moreover, samples of larvae were also collected from
adjacent areas outside the nearly land-locked fjord, and significant fractions (10 – 20%) of
these possessed the gene marker, identifying them as offspring of the farmed cod. The new
experiment conducted in 2008 was based on controlled spawning and daily measurements of
fertilised eggs that were then released exactly in the same location and depth as the net cages
the two previous years. The results from the genetic analyses will be discussed in relation to
the dispersal distance from the spawning site, the tidal water exchange between
Heimarkspollen and adjacent waters, and the general hydrographical characteristics of the
area investigated.
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Plenary
BIO-PHYSICAL MODELS: AN EVOLVING TOOL IN MARINE ECOLOGICAL
RESEARCH
A. Gallego
Fisheries Research Services, Marine Laboratory. PO Box 101, 375 Victoria Road, Aberdeen AB11 9BD,
SCOTLAND; email: a.gallego@marlab.ac.uk
Although they have been in use for some time, bio-physical models are still a relatively new
tool in the study of the ecology of marine zoo- and ichthyoplankton. As the range of specific
applications has expanded so has their level of complexity and sophistication. From original
assumptions of zero-drag, neutrally buoyant particles whose transport was simulated by a
simple particle-tracking model, we have developed true bio-physical models where the
“particles” represent biological entities with increasingly sophisticated sub-models simulating
their development, survival and behaviour. Here I present the results of a modelling
experiment to illustrate the effects of increasing model complexity on the final distribution of
“particles” (e.g. representing early-life stages of marine fish). The outcomes are widely
applicable and demonstrate the importance of selecting the appropriate level of complexity
required for the specific research objectives.
ORIENTATION BEHAVIOUR AND ITS ONTOGENY IN THE PELAGIC LARVAE
OF MARINE, DEMERSAL FISHES
Jeffrey M Leis 1 and Claire B Paris 2
1
Ichthyology, Australian Museum, Sydney, NSW, Australia; e-mail of presenting author:
jeff.leis@austmus.gov.au
2
Applied Marine Physics, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Florida,
USA
For small larvae embedded in a moving water column, orientation in the pelagic environment
is challenging. Yet, for behaviour of larvae to have a major influence on dispersal, orientation
ability is essential. Larval reef fishes have good orientation abilities by the time they settle:
larvae do not swim about randomly. Combined with their good swimming abilities, this can
greatly influence dispersal. Our work in the both the Atlantic and Pacific Ocean using both
wild and reared larvae of reef fishes has recently concentrated on the ontogeny of this
behaviour in situ, on the sensory cues involved, and on developing new means of studying
orientation. Orientation abilities develop early in ontogeny, and there is little ontogenetic
increase in orientation precision. There are, however, ontogenetic changes in orientation.
Similarly, sensory abilities also develop early, but they improve during ontogeny. To study
orientation of fish larvae in situ, a diver-observation approach has been used by the Australian
Museum team for some time, and now the University of Miami team has developed the
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Plenary
OWNFOR (Orientation With No Frame of Reference) apparatus to fill the gaps of the diver
approach, and to extend it. Our research on the ontogeny of orientation, and the sensory cues
used for orientation is shedding light on the remarkable behavioural abilities of larval fishes,
and shows how larval fishes may directly and indirectly influence their dispersal. This year,
with support from the Hermon Slade Foundation and an Australian Museum Research
Fellowship, we began a combined approach to the study of larval-fish orientation in situ that
is designed to overcome limitations of the diver observation method.
FATE OF COMPETENT LARVAE UNDER UPWELLING-DOMINATED
CONDITIONS: THE CASE OF TWO INVERTEBRATE GROUPS ALONG THE
CENTRAL COAST OF CHILE
Alvaro T. Palma
Center for Advanced Studies in Ecology and Biodiversity (CASEB), Departamento de Ecología. P. Universidad
Católica de Chile. Alameda 340, Santiago, Chile; email: apalma@bio.puc.cl
The coast of Chile is characterized by its north-south orientation, and by being fairly exposed.
A well-developed seasonal anticyclonic high-pressure system usually translates into coastal
upwellings during the Spring-Summer months, which in turn deeply influence the larval
delivery dynamics of coastal species. Here I present the results of two studies conducted
under this dynamic scenario for two groups: the gastropod Concholepas concholepas, and
several brachyuran decapod species. In the case of C. concholepas the occurrence of reverse
vertical migration of late stage larvae is proposed as the main mechanism explaining the
counterintuitive pattern of epineustonic larvae being present between the shore and the
upwelling front during upwelling-favourable wind conditions. In the case of brachyuran
species (crabs), larval influx towards settling grounds as well as abundance of older
individuals was quantified. The main factor taken into account for the design of these surveys
was that each location had sites with contrasting conditions of coastal exposure, thus
comparisons were made at different peninsulas several hundreds of kilometers apart. The
hypothesis is that irregularities along the coastline (i.e. exposed vs. protected sides of a
peninsula) represent scenarios that generate differences in the amount of larvae that arrive,
and possibly settle, this being greater at protected sites. For most of the brachyuran species,
oceanographic factors (mainly associated to protected sites) were responsible for a greater
amount of settlers, but processes operating after settlement could obliterate those signals.
These results highlight the importance of considering both pre- and post-settlement factors
together with autoecological (e.g. vertical migration behaviour) aspects, in order to
understand ecological patterns of meroplanktonic species.
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
CIRCULATION PATTERNS AND DECAPOD LARVAE DISTRIBUTION IN A
COASTAL UPWELLING ECOSYSTEM
Cátia Bartilotti1, Álvaro Peliz2, A. Miguel P. Santos1, Henrique Queiroga3 and Antonina
dos Santos1
1
Instituto Nacional de Recursos Biológicos- IPIMAR, Avenida de Brasília, s/n, 1449-006 Lisboa, Portugal;
email of presenting author: cbartilotti@ipimar.pt
2
Instituto de Oceanografia, Faculdade de Ciências da Universidade de Lisboa, Edifício IO, Campo Grande
1749-016 Lisboa, Portugal.
3
Departamento de Biologia, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
The spatial distribution of decapod larvae off the northwest Portuguese shelf was analysed.
Two grid samplings were performed: a first one to characterise the hydrology and circulation
of the area and a second one addressing physical and biological parameters. Before plankton
sampling a coastal upwelling situation was observed, with a southward jet of cold waters near
the coast and a poleward current of warmer waters in the shelf break and slope. During
plankton sampling there was a relaxation of the upwelling conditions due to an inversion in
the wind direction, which induced convergence conditions, and consequently, slope warm
waters invaded the shelf. A frontal structure separating the two northern transects from the
two southern ones was observed. Most of the decapod larvae present were associated with
upwelled waters and with the deeper intrusion of warmer offshore waters. Eualus occultus,
Pandalina brevirostris, Callianassa subterranea, Upogebia pusilla, Anapagurus spp.,
Liocarcinus spp. and Polybius henslowi larvae were distributed along meridionally elongated
patches parallel to the coast inshore of the 200 m isobath aligned in two different fronts.
Solenocera membranacea, Plesionika spp., Bathynectes maravigna and Parthenope spp.
larvae were distributed along the 200 m isobath, while, Diogenes pugilator and Necora puber
larvae were concentrated near the shore along a band parallel to the 30 m isobath. These
results seem to demonstrate that in the Portuguese continental shelf decapod larvae are found
close to their parental populations: inner shelf species larvae (e.g. D. pugilator) are distributed
close to the shore, with maximum of larval abundances along the 30 m isobath; shelf species
(e.g. E. occultus) are mainly distributed along the continental shelf, with maximum of larval
abundances in middle shelf; finally slope species larvae (e.g. B. maravigna) can be found
along the 200 m isobath, in the vicinity of the shelf break.
EVIDENCE OF NEARSHORE FISH LARVAL RETENTION AT THE ARRÁBIDA
MARINE PARK (PORTUGAL)
R. Borges1 and E. J. Gonçalves2
1
CCMAR. Algarve University. Campus de Gambelas. 8000 Faro, Portugal; email of presenting author:
rborges@ispa.pt
2
Eco-Ethology Research Unit. Instituto Superior Psicologia Aplicada. R. Jardim Tabaco, 34. 1149-041 Lisboa,
Portugal.
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
Sampling in temperate nearshore environments is difficult and little effort has been done to
know the composition and dynamics of larval fish assemblages occurring near reefs, their
distribution patterns and possible influence over recruitment variation. The composition of the
nearshore larval fish assemblages at the Arrábida Marine Park and small scale variations in
their temporal, horizontal and vertical patterns of distribution were investigated. Along the
spring and summer period, monthly comparisons were made between samples collected using
sub-surface trawls from a distance of less than 50m from the shore with samples collected two
miles offshore; the abundance and diversity of fish larvae with increasing distance from shore
were also investigated from samples collected along transepts perpendicular to the shoreline.
Results indicate a sharp decrease in fish larvae abundance and diversity at a short distance
from shore. On the other hand, very-nearshore bottom trawls (max depth ca 13m) performed
using a net attached to an underwater scooter revealed a small scale vertical profile in the
structure of the assemblages, with larvae of some species aggregating close to the bottom
during all their pelagic period. These results suggest the need to integrate different sampling
methods to understand nearshore fish larval ecology and dynamics, namely the mechanisms
of larval retention close to reefs. Differences found between species in their pattern of
distribution and the relevance of the results obtained to the management of the marine park
are discussed.
REVEALING PATTERNS OF LARVAL DISPERSAL AND CONNECTIVITY:
BRINGING MULTIPLE TOOLS TO THE TABLE
Jennifer E. Caselle1, Satoshi Mitarai2, James Watson2, Robert Warner3 and Dave Seigel2
1
Marine Science Institute, University of California, Santa Barbara; email of presenting author:
Caselle@msi.ucsb.edu
2
Institute for Computational Earth System Science (ICESS), University of California, Santa Barbara
3
Ecology, Evolution and Marine Biology, University of California, Santa Barbara
Most marine organisms have a bipartite life cycle with relatively sedentary adults and
planktonic larval dispersal. The large range in life-histories and larval behaviors of marine
larvae as well as oceanographic features and flow conditions, creates the possibilities for long
distance dispersal yet also may serve to limit dispersal and enhance local retention. Scale of
dispersal and patterns of connectivity between populations have important consequences for
population dynamics, species interactions, spatial and temporal patterns of distribution,
population genetics, macroeveolution, biogeography, conservation and management. Despite
this, characterizing these scales and patterns has been extremely difficult in practice. I present
recent work using simple flow models and empirical measures of recruitment of temperate
reef fishes to explore potential scales of dispersal and patterns of population connectivity
along the coast of California. Our studies of connectivity so far have suggested two important
features. First, larval dispersal distances are often shorter than that suggested by simple
advection-diffusion models; self-recruitment and limited dispersal may be a common feature
in coastal systems. Second, gross level patterns of dispersal in time and space can be predicted
by simple flow models and oceanographic indices. It is clear that no single method or study
will provide general answers to these issues and a better understanding of the role of dispersal
in marine systems will be gained by a synthetic and multi-disciplinary approach.
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
GEOGRAPHIC DISTRIBUTION OF INTERTIDAL BARNACLES IN ASIA:
IMPLICATIONS FOR? LARVAL SUPPLY PATTERNS IN NW PACIFIC
Benny K. K. Chan1, Wai Chuen Ng2, Ling Ming Tsang3, K. H. Chu3 and Gray A.
Williams2
1
Research Centre for Biodiversity, Academia Sinica, Taiwan; email of presenting author:
chankk@gate.sinica.edu.tw
2
The Swire Institute of Marine Science and Division of Ecology & Biodiversity, School of Biological Sciences,
The University of Hong Kong, Pokfulam Road, Hong Kong
3
Department of Biology, The Chinese University of Hong Kong, Hong Kong
Patterns of biodiversity along the coastlines of the NW Pacific are poorly documented,
making assessment of species distributions, and potential changes in those patterns,
problematic. In the present study, quantitative transect surveys were undertaken along a
latitudinal gradient from Japan to South China. On the Pacific coast of Honshu, Japan, the
high shore is occupied by Chthamalus challengeri and Hexechamaesipho pilsbryi. In
Okinawa, Nesochthamalus intertextus is the most common high shore barnacle. C.
challengeri is also recorded in Zhoushan on the east coast of China. In contrast to these sites,
the high shore of the Taiwan intertidal is colonized by H. pilsbryi, Chthamalus malayensis
and C. moro. In Hong Kong, the high shore inhabitant is C. malayensis. In the mid shore,
tetraclitid barnacles are the major space occupiers, with Tetraclita kuroshioensis and T.
japonica common in Honshu, Okinawa and Taiwan. In Zhoushan and Hong Kong, the mid
shore is colonized by T. squamosa and T. japonica, but reverts to being dominated by T.
kuroshioensis in Hainan. The distribution of C. challengeri appears to be associated with the
Oyashio Current, which limits its distribution to temperate waters. Larvae of T. kuroshioensis,
and the northern populations of T. japonica and H. pilsbryi are probably transported by the
Kuroshio Current, resulting in their broad distribution along the W Pacific coastline from
Taiwan to Japan. The presence of T. kuroshioensis in Hainan is probably a result of the winter
penetration of the Kuroshio Current into the South China Sea. The distinct population of N.
intertextus in Okinawa suggests Okinawa may have oceanographic connections with
Polynesian waters as this species has previously been recorded as common in Polynesia. T.
squamosa, T. japonica and C. malayensis occur in the South China Sea and their larvae
appear to be transported mainly by the South China Sea Surface Current, flowing northwards
along the China coastline and entering the Taiwan Strait. Detailed mapping of intertidal
barnacles highlights their biogeographic distribution closely reflects coarse scale
oceanographic currents. Such currents are likely to play a major role in the distribution of
most species which have a planktonic larval stage, and may provide an important clue to
possible species boundaries in this poorly understood region.
VERY SMALL TEMPORAL SCALE VARIABILITY OF SETTLEMENT OF
CHTHAMALUS SPP. IN SINES (SW PORTUGAL): INFLUENCE OF SEA BREEZE
AND DAYLIGHT FLOOD
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
Teresa Cruz123, Joana Fernandes12, Paulo B. Oliveira4, Maria Manuel Angélico4, Nayana
Lima1, João J. Castro123, Stephen J. Hawkins5 and Jesús Pineda 6
1
Laboratório de Ciências do Mar, Universidade de Évora, Apartado 190, 7520-903 Sines, Portugal; email of
presenting author: tcruz@uevora.pt
2
Centro de Oceanografia, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal
3
Departamento de Biologia, Universidade de Évora, Évora, Portugal
4
Instituto Nacional de Investigação Agrária e das Pescas - IPIMAR, Lisboa, Portugal
5
College of Natural Sciences, Bangor University, Wales, UK
6
Woods Hole Oceanographic Institution, Woods Hole, USA
Previous studies on tidal settlement (during one tidal cycle) of Chthamalus spp. (Crustacea,
Cirripedia) in Sines (SW Portugal) showed that settlement was highest during spring diurnal
high tides which occur during the afternoon in this region. This pattern was also explained by
the onshore sea breeze that is normally more intense during the afternoon in the main
settlement period of these barnacles (summer). However, due to the dependence between tidal
cycle and period of the day, it was impossible to unconfound the influence of the sea breeze
from the tidal cycle. Here we tested the hypothesis that settlement of Chthamalus spp. was
highest during the afternoon (12-18h) independently of the tidal cycle by measuring
settlement of Chthamalus spp. in artificial substrata continuously immersed and attached to a
buoyant platform in the Port of Sines during the summer of 2006. Additionally, at the same
site we have sampled cyprids of Chthamalus spp. in the neuston and bottom water layers at
different hours. Cyprids of Chthamalus spp. were neustonic during the day. We found that
settlement was almost nil during the night, but during the day it was not always higher during
the afternoon. We suggested that daylight flood could be the factor influencing settlement. In
the summer of 2007, using the same sampling conditions, we tested the hypothesis that
settlement of Chthamalus spp. was highest during the daylight flood. The hypothesis was
supported. Settlement was much higher during daylight flood then during daylight ebb or
during the night. The daylight flood can be an important mechanism of transporting larvae
onshore.
NOISE WORKS: BENTHIC INVERTEBRATE LARVAE RESPOND TO SOUND
A. R. Davis, J. Stocks, T. E. Minchinton
Institute for Conservation Biology and School of Biological Sciences, University of Wollongong, NSW 2522,
Australia; email of presenting author: adavis@uow.edu.au
The influence of sound on vertebrate marine larvae has attracted considerable interest,
whereas the response of invertebrate larvae has received scant attention. We tested two
hypotheses with invertebrate larvae in southeast Australia: (i) sound affects the swimming
behaviour of larvae, and (ii) larvae respond differently to natural and anthropogenic sounds.
We exposed larvae of the bryozoan Bugula neritina and two molluscs, the snail Bembicium
nanum and the oyster Crassotrea gigas, to three sound recordings in the laboratory: (i) natural
sound (the swash of waves on a shore), (ii) anthropogenic sound (an outboard motor), and (iii)
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
no sound (control). Video recordings were made of swimming larvae in replicate petri dishes.
All three species modified their swimming behaviour in response to sound, but effects were
species-specific. Relative to the controls, Bembicium nanum increased swimming movements
in response to natural and anthropogenic sound, while Bugula neritina slowed their
swimming following exposure to anthropogenic sound, but not natural sound. Unfed larvae of
C. gigas did not respond to sound, but fed larvae of this species increased their swimming
activity in response to natural sound. It remains unclear how invertebrate larvae detect sound
and whether the changes in swimming behaviour we have observed may influence their
patterns of distribution in the water column or settlement in the field.
A MODELLING STUDY OF NORWAY LOBSTER LARVAL DISPERSAL IN
SOUTHERN PORTUGAL.
Jesús Dubert1, Martinho Marta-Almeida2, Álvaro Peliz3, Antonina dos Santos4 and
Henrique Queiroga5
1
Departamento de Física and CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal; email of presenting
author: jdubert@ua.pt
2
Departamento de Física and CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal
3
Instituto de Oceanografia, Fac Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
4
Instituto Nacional de Recursos Biológicos- IPIMAR, Av. Brasília, s/n, 1449-006 Lisboa, Portugal
5
Dep. de Biologia and CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal
A set of simulations using a validated and realistic parameterization of a numerical model was
conducted for the south and southwest Portuguese regions, as an attempt to understand the
dispersal and fate of larvae of the Norway lobster Nephrops norvegicus. Larvae were
introduced in the model as Lagrangian particles with 5 different behavioral scenarios
concerning larval ability to migrate vertically and its vertical distribution in the water column.
The effects of temperature on growth rate were incorporated in the model, and the larvae were
tracked individually.
The end point of the simulations was the position of the larvae when they reached competency
at age 1. Age 1.25 was also considered in order to simulate a possible delay in settling due to
lack of an appropriate substrate. The results showed that the majority of the larvae reached
age 1 near the hatching area along the southern shelf, while low exchange of larvae between
the south and the west coasts was observed, especially for behavioral scenarios where larvae
remained in relatively shallow waters. Scenarios where larvae diurnal vertical migration and
delayed settlement until age 1.25 indicated a tendency for westward motion due to
interactions with the Mediterranean Undercurrent. Self-recruitment to the Algarve stock was
estimated at 0.2 to 0.5%, raising the concern that this stock may be experiencing recruitment
limitation.
ONTOGENY OF CRITICAL SWIMMING SPEED OF WILD-CAUGHT AND
LABORATORY-REARED RED DRUM LARVAE (Sciaenops ocellatus)
A. Faria1 2, A. Ojanguren3, L. Fuiman3 and E. Gonçalves1
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
1
Eco-Ethology Research Unit. Instituto Superior Psicologia Aplicada. R. Jardim Tabaco, 34. 1149 Lisboa,
Portugal; email of presenting author: afaria@ispa.pt
2
CCMAR. Algarve University. Campus de Gambelas. 8000 Faro, Portugal.
3
University of Texas at Austin Marine Science Institute
It is clear from recent studies on the behavioural abilities of late-stage reef fish larvae that
they are strong, enduring swimmers. Swimming abilities may be important in terms of the
potential for larvae to move between locations on a small scale, to move vertically to access
different current or prey regimes, to move away from reefs at hatching, or to move among
habitats at settlement. Critical swimming speed (Ucrit) provides a useful maxima performance
estimate of swimming speed of larvae. In laboratory swimming chambers we examined the
Ucrit of red drum larvae (Sciaenops ocellatus) through its ontogeny and compared the
swimming performance of laboratory-reared larvae to that of wild-caught red drum. Ucrit
increased with development, even though variation at any developmental stage was large. We
found a significant difference on critical speeds before and after the completion of flexion.
Ucrit values, for wild larvae, increased from 9.7 to 22.2 cm s-1 over the range of 8.3 to 16.3
mm (TL), and from 1.1 to 20.5 cm s-1, over the range of 3.0 to 19.1 mm (TL) for reared
larvae. There were no significant differences in swimming performance between wild and
reared larvae. Results are discussed in light of the available information of swimming abilities
in other coastal fish larvae.
IS MORTALITY IN THE EARLY LARVAL STAGE THE KEY TO
UNDERSTANDING RECRUITMENT VARIABILITY IN SNAPPER, PAGRUS
AURATUS?
Paul A. Hamer1 and Gregory P. Jenkins2
1
Marine and Freshwater Fisheries Research Institute, P.O. Box 114, Queenscliff 3225 Australia
Department of Zoology, University of Melbourne, and MAFFRI, P.O. Box 114, Queenscliff 3225 Australia;
email of presenting author: gjenkins@unimelb.edu.au
2
Port Phillip Bay is the primary natal source of the western Victorian stock of snapper, Pagrus
auratus. Juvenile recruitment variability in Port Phillip Bay is high, and this variability is
reflected in the adult stock structure. We undertook ichthyoplankton sampling in late spring
and early summer over three years to investigate the stage in the early life history when this
recruitment variability is generated. We found that the number of snapper larvae in Port
Phillip Bay varied by at least 20 fold among spawning years. When larval abundances were
low there were no larvae larger than 5 mm (approximately 10 days age). Variation in the
number of snapper larvae was closely matched to the number of small juveniles at
approximately 4 months age collected by concurrent monitoring of juvenile recruitment. This
indicated that juvenile recruitment variation in Port Phillip Bay was driven by processes that
influence the production and survival of the larval stages (i.e. first few weeks of life).
Furthermore, annual variation in the abundance of snapper larvae was reflected by variation in
the total abundance of fish larvae. This suggests that processes affecting production/survival
of snapper larval stages in Port Phillip Bay are also influencing a range of other species. We
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
hypothesise that natural variability, in as yet unknown environmental factors, is influencing
the production of planktonic food that is, in turn, influencing the growth and survival rates of
snapper larvae in Port Phillip Bay.
VARIABILITY IN LARVAL BEHAVIOUR AT DIFFERENT STAGES OF
DEVELOPMENT FOR SPECIES OF LOBSTER, ABALONE AND URCHIN FROM
NEW ZEALAND
Lesley McLeod1,2, Nicole Phillips2 and Alison MacDiarmid1
1
National Institute of Water & Atmospheric Research Ltd, 295-301 Evans Bay Parade, Wellington, New
Zealand; email of presenting author: l.mcleod@niwa.co.nz
2
School of Biological Sciences, P.O. Box 600, Victoria University of Wellington, Wellington, New Zealand
6140
Hydrodynamic models that simulate complex coastal currents are providing insights into how
far larvae may be dispersed or retained under various scenarios of wave activity, current
strength and coastal morphology. However, dispersal of larvae is potentially influenced by
both hydrodynamics (i.e. physical factors) and larval characteristics/behaviours (i.e. biological
factors); yet, for the most part, larval behaviour is ignored in dispersal models. Critical gaps in
our understanding of larval behaviour limit our model inputs and the interpretation of
modelling outputs.
We are using a flume system to examine larval behaviour of coastal New Zealand invertebrate
species: southern rock lobster (Jasus edwardsii), abalone / paua (Haliotis iris) and sea urchin /
kina (Evechinus chloroticus). We chose these focal species because they have great economic
and cultural importance to New Zealand, and because they have different life history
strategies and traits such as larval size and duration. For each of these species we are
examining variability in larval behaviour at different stages of development and in response to
temperature, pressure and water flow rates.
The results from this research will be used to enhance the predicative capabilities of larval
dispersal models, thereby improving management strategies for these species along discrete
areas of coastline in New Zealand.
WIND AND TIDE AS PHYSICAL FORCING AGENTS OF THE SUPPLY OF CRAB
MEGALOPAE TO THE BAY OF CADIZ (SW SPAIN)
Ainhoa O. Olaguer-Feliú1, Henrique Queiroga2 and Juan Ignacio González-Gordillo1
1
CACYTMAR (Institutos de Investigación), Campus Universitario de Puerto Real, 11510 Puerto Real - Cádiz –
Spain; email of presenting author: ainhoa.ortega@uca.es
2
CESAM (Centro de Estudos do Ambiente e do Mar), Departamento de Biologia da Universidade de Aveiro,
Campus Universitário de Santiago, 3810-193 Aveiro- Portugal.
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
Planktonic larvae of estuarine invertebrates can display two main life strategies during their
development. The first strategy is to remain within the coastal parental habitat for their entire
larval life. The second strategy is to disperse to offshore waters during early larval stages.
This implies that species with the second strategy need to cope with often extreme
oceanographic and atmospheric conditions forcing to on-shore. Late larval stages,
consequently, must be able to return to the coast in order to settle. Here we examine the
influence of wind regime and tidal range on the supply of crab megalopae to coastal habitats
within the Bay of Cádiz. In order to identify patterns in the supply of larvae and possible time
lags related to the considered physical forces, temporal variation in the abundance of
megalopae, wind stress, subtidal sea level (SSL) and tidal range were analyzed using standard
time series analysis and multiple regression. Our data indicate species with both strategies are
present within the studied area and that when exported offshore, larvae are able to take
advantage of off-to-onshore winds to return to the coast. Onshore winds favour upwelling,
and cause a drop of SSL registered in the coast after a lag of -2d. Delayed one more day these
winds show to enhance megalopal supply, with a maximum correlation found when
perpendicularly onshore winds blow. These results suggest megalopae are located in offshore
waters but close to shore, where they occupy the deep water mass that renews that out-flushed
under upwelling conditions. Once close to the coast, the transport of megalopae is coupled
with the tidal regime to finally reinvade the coast, as showed by a fortnight cycle of supply
with high abundance of megalopae during spring tides and very low during neap tides.
SPATIAL VARIABILITY OF LARVAL ABUNDANCE AND SIZE STRUCTURE IN
THE INVASIVE GASTROPOD CREPIDULA FORNICATA: LARVAL TRANSPORT
AND DILUTION EFFECTS AT A BAY SCALE.
F. Rigal, T. Comtet and F. Viard
Adaptation & Diversité en Milieu Marin UMR7144 CNRS UPMC Station biologique de Roscoff; email of
presenting author: rigal@sb-roscoff.fr
If suitable substrates are available for metamorphosis of competent pelagic larvae, the larval
development time should be inversely correlated to the potential for larvae to disperse far
from their site of release. To investigate how much dilution effects due to mortality during
development time and larval transport may influence the larval pool dynamics, we
investigated the abundance and size distribution of larvae of the invasive gastropod Crepidula
fornicata in ten sites of the Bay of Morlaix (Brittany; France) where previous studies in one
site located in the inner part of the bay showed a continuous release of larvae during an
extended period. Plankton sampling was carried out three times every two to three weeks
during the summer 2006. Sea surface temperature, salinity and chlorophyll a were measured
at each site and date. Besides abundance and size, the competent status of the larvae was
evaluated using a simple morphological feature (brimmed larvae) experimentally shown to be
highly correlated with competence. At each site and date, low abundances and very low
numbers of competent larvae were observed suggesting (1) a rapid transport of the larvae
outside the study area or/and (2) a high mortality rate during larval development.
Nevertheless, our results showed a clear and stable spatial pattern with higher abundances and
smaller mean larval size in the inner part of the baywhich might be explained by the
8th Larval Biology Symposium
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Larval behaviour, dispersal and mortality
Oral
continuous release of larvae in the inner bay. Larval transport outside the bay may thus be an
important component of the larval dynamics in the study area. This hypothesis deserves
complementary analyses, in particular the modeling of larval transport using a bio-physical
model.
IF ONLY I WERE LONGER! THE RELATIONSHIP BETWEEN MORPHOLOGY,
BEHAVIOUR AND HYDRODYNAMICS IN DISPERSAL DURING THE EARLY
LIFE HISTORY OF COASTAL NEWFOUNDLAND FISHES
R. Stanley1, P. Snelgrove2, and L. Guan3
1
Ocean Sciences Centre/Biology Dept., Memorial University, St. John’s, NL, Canada, , A1C 5S7; email of
presenting author: rstanley@mun.ca
2
Canada Research Chair in Boreal and Cold Ocean Systems, Ocean Sciences Centre/Biology Dept., Memorial
University, St. John’s, NL, Canada.
3
Department of Earth and Ocean Science, University of British Columbia, Vancouver, Canada, V6T 1Z4.
Behaviour is potentially a significant component of dispersal in the early life history of
marine fishes, but intrinsic to understanding behaviour is the relationship between kinematic
capabilities and larval morphology. Traditionally total length has been used to predict
swimming ability, and analysis of corresponding swim data and images of larvae from several
species from coastal Newfoundland indicated that total length and body area were the most
effective predictors of swimming ability throughout ontogeny. In order to determine how this
relationship might be relevant to field distributions, we examined ichthyoplankton survey data
in the context of this morphometric kinematic relationship. Lloyd`s index of mean crowding1
was utilized to illustrate how morphology relates to spatial structure for several fish species.
Field survey data suggests that spatial patchiness increases as larval length increases. The
interaction of individual larvae with their environment was also considered by calculating
Reynolds number as a function of ontogeny. Typically, larvae hatch into a viscous
environment where swimming is inefficient. The interaction of larvae with their environment
is therefore closely related to length not only in terms of swimming capacity but also in terms
of viscosity effects. Meshing field data with lab swimming data will allow us to determine
whether the transition from a viscous to an inertial swimming environment coincides with the
increase in patchiness at later larval stages. This information, coupled with the morphometric
kinematic data, suggests that older larvae can actively contribute to spatial structure.
Application of these results has the potential to improve biophysical models and better
illustrate the role of behavior in early stage larval dispersal.
1
Lloyd, M. 1967. Mean Crowding. Journal of Animal Ecology 36:1-30
CAN DIFFERENT EARLY LIFE HISTORY STRATEGIES EXPLAIN DIFFERENT
RECRUITMENT PATTERNS FOR NORTHERN ROCK SOLE AND ALASKA
PLAICE IN THE EASTERN BERING SEA?
William T. Stockhausen1, Janet Duffy-Anderson1, Albert J. Hermann2 and Thomas K.
Wilderbuer1
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
1
Alaska Fisheries Science Center, National Marine Fisheries Service, 7600 Sand Point Way NE, Seattle, WA
98115-6349, USA; email of presenting author: william.stockhausen@noaa.gov
2
NOAA/Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA, 98115-0070, USA.
In the Eastern Bering Sea, the flatfish species northern rock sole (Lepidopsetta polyxystra:
NRS) and Alaska plaice (Pleuronectes quadrituberculatus; AP) utilize similar spawning and
nursery habitats and exhibit similar timing in the time early life stages are in the water column
and in settlement. However, the two species engage in substantially different early life history
strategies (demersal vs. pelagic eggs, possible differences in vertical migration). We used a
coupled biophysical physical model to address the hypothesis that differences in the
recruitment trajectories these species have undergone over the past 30 years are attributable to
differences in their early life history characteristics. The model consisted of an individualbased biological model incorporating simple behavior for early life stages coupled to a 3dimensional (3D) oceanographic model to simulate dispersion of eggs and larvae from
spawning grounds prior to settlement. We predicted relative annual recruitment for 1978-2004
for both species based on the fraction of juveniles settling in favorable habitats at the end of
June each year following release of newly-hatched larvae (NRS) or eggs (AP) during the
preceding April. Our results suggest that, while the modeled differences in early life stages
may lead to somewhat different patterns in recruitment, the observed differences in
recruitment are most likely driven by other factors such as variation in spawning location or
density-dependence.
ECOLOGY OF STOMATOPOD LARVAE IN HONG KONG WATERS
Ricky W. K. Tang and Cynthia Yau
The Swire Institute of Marine Science, Faculty of Science, The University of Hong Kong, Cape d'Aguilar Road,
Shek O, Hong Kong SAR; email of presenting author: rkytang@graduate.hku.hk
Stomatopods, or mantis shrimps, are important commercial species in Hong Kong waters, yet
very little is known of the ecology of the nine species reported. Intensive fishing activities
have resulted in serious depletion of local marine resources, and there are urgent demands to
impose protection of critical spawning and nursery areas, yet information on such habitats is
scarce. A comprehensive zooplankton sampling survey was therefore conducted monthly from
February 2007 to April 2008, which aimed at assessing the larval ecology of stomatopods in
Hong Kong waters for the first time in terms of their seasonal and geographical abundance. A
total of 14 sampling stations were selected: 7 in southwestern waters off Lantau Island (under
the influence of the Pear River discharge); 7 from northeastern waters in Tolo Harbour (a
more oceanic environment). A bongo net of 50 cm mouth diameter and 500 µm mesh size was
used in 10-min oblique tows. A Conductivity-Temperature-Depth recorder was used to collect
physical environmental parameters at the start of each tow. At least 4 putative morphotypes of
stomatopod larvae were determined, but species identification was not possible because of the
lack of relevant taxon-specific identification keys. DNA barcoding, using two conserved gene
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Oral
regions in the mitochondrial DNA (COI and 16S rRNA), was therefore employed to match
the DNA sequences of known adults to those of the different unknown larval morphotypes.
Two peaks in larval occurrence were found, with higher total densities in May (24.86 ind. m-3)
and October (42.80 ind. m-3) of 2007. Larval density in southwestern waters ( =1.52 ind. m3
) was significantly higher than that in northeastern waters ( =0.03 ind. m-3) (Mann-Whitney
Test; p<0.0001). Preliminary results from this study suggest that southwestern waters of Hong
Kong may be an important spawning ground for stomatopods, particularly during the summer
season.
LIVING ON THE EDGE: LARVAL CHOICE AND POSTSETTLEMENT EVENTS
DETERMINE THE DISTRIBUTION OF THE INTERTIDAL ASCIDIAN PYURA
PRAEPUTIALIS
X. Turon1, M. A. Becerro1 and A. R. Davis2
1
Centre for Advanced Studies of Blanes (CEAB, CSIC), Accés a la Cala S. Francesc 14, 17300 Blanes (Girona),
Spain; email of presenting author: xturon@ceab.csic.es
2
School of Biological Sciences, University of Wollongong, NSW 2522. Australia
Pyura praeputialis is a large solitary ascidian that dominates the intertidal and upper
sublittoral habitats in New South Wales (Australia). It occurs normally in large clumps and is
rarely found isolated. We investigated how active larval choice and postsettlement events
shape this pattern of distribution. Juveniles (< 3 cm in diameter) occurred disproportionately
on adult individuals or on patches of algal turf, even though most of the available substratum
was bare rock. In the laboratory, larvae settled readily in the presence of adults, other ascidian
species, or a variety of algal species. In contrast, settlement rates were significantly lower
when only bare rock was available. Surprisingly for an intertidal species, recruits (20 days
old) died within one hour of aerial exposure. In contrast, recruits placed amid adult clumps or
algal turf resisted desiccation for at least 4 hours. On bare rock in the field, juveniles < 2 cm
in diameter died within days, compared to over 50% survivorship for those on adult clumps or
algal turf. Microhabitat associated temperature was up to five degrees Celsius lower in turf or
adult clumps than on rock surfaces. Taken together our data indicate that a combination of
factors shape the aggregated distribution found in Pyura praeputialis. Larval behaviour
favours initial settlement on adults and algae, which function as spatial refuges to the
otherwise fatal environmental conditions of the intertidal habitat. Physical stress, particularly
associated with desiccation and temperature, plays a fundamental role in the fine scale
distribution of this ascidian species.
8th Larval Biology Symposium
Lisbon, 2008
Larval behaviour, dispersal and mortality
Poster
THE ROLE OF VERTICAL BEHAVIOUR IN THE DISPERSAL OF
INVERTEBRATE LARVAE IN THE BAY OF BISCAY, A HIGHLY VARIABLE
ENVIRONMENT.
Sakina-Dorothée Ayata1, Pascal Lazure2, Martin Huret3 and Eric Thiébaut4
1
Equipe Ecologie Benthique, UMR 7144, UPMC-CNRS, Station Biologique, BP 74, 29682 Roscoff Cedex,
France; email of presenting author: sakina.ayata@normalesup.org
2
IFREMER, Département Dynamique de l’Environnement Côtier. BP70 29280 Plouzané, France.
3
IFREMER, Département Ecologie et Modèles pour l’Halieutique, BP21105, 44311 Nantes Cedex 03, France.
4
Equipe Ecologie Benthique, UMR 7144, UPMC-CNRS, Station Biologique, BP 74, 29682 Roscoff Cedex,
France.
In marine environment, larval dispersal is a key process in population dynamics,
biogeography, and speciation. To study the transport of a large number of small planktonic
larvae, that would be very hard to track in situ, such as polychaete larvae, numerical modeling
is a powerful tool. Although such approaches were mainly based on physical computations
only in order to simulate the transport of passive particles under theoretical or realistic
hydrodynamical conditions, the larvae do not always behave passively. Recent works have
highlight the need to include specific biological traits, like spawning location and timing,
swimming behaviour and settlement conditions, in numerical models coupling both physics
and biology.
The present work focuses on the variability of the dispersal of invertebrate larvae in the Bay
of Biscay (North-East Atlantic), where river runoffs and wind conditions cause strong interannual, seasonal and mesoscale variability in circulation patterns. A coupled bio-physical
model is used to explore the consequence of vertical swimming behaviour on horizontal
dispersal and larval exchanges between distant populations (connectivity). The
hydrodynamical model that calculate 3-dimensional current fields is forced by realistic river
runoffs, meteorological conditions, tides, and climatology of two contrasted years (2002 and
2004). The lagrangian model of larval transport takes into account the main spawning
locations, vertical turbulence, and specific swimming behaviours (ontogenic and
nycthemeral). The results indicate that the hydroclimatic specificities of the Bay of Biscay
(river runoffs, wind conditions) are responsible for a high variability of the larval dispersal
and exchanges. This variability depends mainly on the spawning locations and dates: larvae
released from very close populations can undergo very different trajectories. But the results
also suggest that swimming behaviours may significantly alter the dispersal of larvae in
coastal and highly variable environment, underlying the necessity to describe more precisely
larval behaviour in situ.
FLUX OF DECAPOD LARVAE FROM NW AFRICA TO CANARY ISLANDS
THROUGH UPWELLING FILAMENTS.
J. M. Landeira1, F. Lozano Soldevilla1, S. Hernández-León2 and E. D. Barton3
1
Departamento de Biología Animal, UDI Ciencias Marinas (ULL), La Laguna, Spain; email of presenting
author: jmlandei@ull.es
2
Laboratorio de Oceanografía Biológica, Facultad de Ciencias del Mar (ULPGC), Las Palmas G.C., Spain.
8th Larval Biology Symposium
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Larval behaviour, dispersal and mortality
Poster
3
Departamento de Oceanoloxía, IIM (CSIC), Vigo, Spain
The distribution and transport of decapod larvae were studied along a filament-eddy system
located in the transition zone between the NW Africa upwelling and Canary Islands waters
during the summer of 1999. Two independent filaments were developed between Cape Juby
and Cape Bojador to merge at 100 km offshore during the cruise. The merged filament
interacted with transient cyclonic and anticyclonic eddies shed from the island of Gran
Canaria. Mesoscale oceanographic features strongly influenced the horizontal distribution of
decapod larvae. Benthic larvae were mainly associated with upwelling filament structures,
while oceanic larvae were related with eddies structures. In this sense, eddies acted as a
mechanism of concentration, while upwelling filaments were dispersive, transporting larvae
from the African neritic zone into oceanic areas and towards the Canary archipelago.
Although this larval contribution may not be quantitatively important to increase the size of
neritic decapod populations of the islands, it may certainly serve to maintain a genetic flow.
Our results suggest that there are clear evidences of connectivity between marine populations
of African and Canaries coast through upwelling filaments.
DISPERSAL OF MUNIDA GREGARIA (DECAPODA: GALATHEIDAE) LARVAE IN
PATAGONIAN CHANNELS OF SOUTHERN CHILE
Roxana León1, Leonardo Castro1 and Mario Cáceres2
1
. Laboratorio de Oceanografía Pesquera y Ecología Larval (LOPEL). Departamento de Oceanografía and Centro
FONDAP-COPAS, Universidad de Concepción, Chile; email of presenting author: lecastro@udec.cl
2
. Facultad de Ciencias del Mar, Universidad de Valparaíso, Av. Borgoño 16344, Valparaíso, Chile
We assessed the Munida gregaria larval dispersal strategy in four Patagonian channels of
Southern Chile. Oceanographic cruises along the channels were carried out in spring 2002 and
2003 and winter 2003. In winter 2003, Zoea I was the most abundant stage in all channels and
no larval stages beyond Zoea IV were observed. In spring of 2002 and 2003, the six larval
stages occurred in all channels; the greater abundance of older larvae suggested that
reproduction took place in winter and larval development in spring. The spatial distribution
analyses by stage revealed that early zoea moved from the inner channel sectors to the outer,
seaward stations. GAM analyses showed that most larval stages were temperature-dependent
and that the salinity range of the youngest zoea was wider than that of the older larval and
postlarval stages, coinciding with the ontogenetic distribution change from estuarine to
seaward zones. The coarse vertical resolution in sampling precluded determining clearly
potential ontogenetic changes in vertical distribution. Residual flows determined with an
ADCP revealed two layers of opposite flows; the shallowest layer moved seaward and the
deeper layer landward. The surface layer was thicker in spring than in winter due to the
seasonal increase in fresh water discharge from melting ice of nearby glaciers. In summary,
the M. gregaria dispersal pattern in the Patagonian channels consisted of an inner channel
8th Larval Biology Symposium
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Larval behaviour, dispersal and mortality
Poster
larval release in winter, followed by an along-channel larval drift and subsequent export to the
continental shelf in spring. The mechanism by which juveniles return to the channels seemed
to be associated with the landward subsurface flow.
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Plenary
SENSORY ORGANS AND BIOMECHANICS IN SETTLEMENT OF CIRRIPEDE
CYPRIS LARVAE: VARIATION WITHIN A RIGID FRAME.
Jens T. Høeg
Institute of Biology, University of Copenhagen, Copenhagen, Denmark; email: jthoeg@bi.ku.dk
Cirripedes are among the most successful sessile organism in the marine environment. Being
dominant in the marine rocky intertidal, cirripedes have also invaded many other habitats
including the deep sea. In addition, many cirripedes are epibiotic on a variety of other
organisms, and among these we find some of the most advanced parasites known among
higher invertebrates. Despite these differences in habitat, all cirripedes use the same type of
larva, the cyprid, to carry out substrate location and attachment. The cyprid can both swim
through the water and actively explore the substratum in a manner different and more
complex than seen in any other invertebrate larvae. On the substratum it can traverse long
distances by walking bipedally on the antennules, using a highly complex system of muscles
and cuticular skeletal elements. The cyprid can change direction while walking, stop to
explore a site and even reverse its path without letting go of the substratum. The specialized
morphology associated with this advanced behaviour is virtually similar across all cirripedes,
irrespective of the type of substratum used for settlement, and it goes a long way in explaining
the success of the taxon. What differs is the specific morphology of the antennular attachment
organ and of the sensory apparatus used to locate and choose the site of settlement. Based on
digital video microscopy, SEM and TEM, we review the biomechanical properties of the
cypris and the diversity of its sensory organs across a range of taxa from widely different
habitats. It appears that there is considerable variation in the sensory apparatus between
groups, but that all balanomorphan species attaching to hard surfaces, ie., those most
implicated in biofouling issues, have a surprisingly similar antennular structures.
LARVAL PROTEOMICS: A NEW TOOL TO INVESTIGATE THE LARVAL
SETTLEMENT MECHANISM AND MODE OF ACTION OF CHEMICAL CUES
Pei-Yuan Qian
Department of Biology & Coastal Marine Laboratory, The Hong Kong University of Science and Technology,
Hong Kong SAR; email: boqianpy@ust.hk
Recently, there have been increasing applications of proteomics (i.e. the study of an
organism's complete complement of proteins) as a useful tool for biomarker investigations in
aquatic biology. However, our understanding of protein expression pattern in marine
organisms, particularly benthos, remains very poor which negatively impacts our
understanding of possible mechanisms of larval metamorphosis, the development of
environmentally friendly antifouling technology, and the application of proteomics
technology for environmental risk assessment (ERA). To understand the molecular
mechanism of larval metamorphosis and the application of proteomics in screening for
antifouling compounds, we have conducted a comparative larval proteome analysis of a
bryozoan (Bugula neritina), two polychaetes (Hydroides elegans and Capitella sp I) and two
8th Larval Biology Symposium
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Larval Settlement: cues, behaviour response and
possible mechanisms
Plenary
barnacle species (Balanus amphitrite and B. trigonus). To clarify the overall profile of protein
expression during larval development and metamorphosis, two-dimensional electrophoresis
(2-DE) was used to compare the proteome maps from developing, pre-and post-settled larvae.
We used tandem mass spectrometer to analyze proteins that were differentially expressed at
competent larval stage and also in response to chemical cues (both negative and positive). For
the first time, using a proteomics approach, we created protein maps for the global protein
expression pattern of marine fouling invertebrate larvae. Our results indicate that proteomics
technology is a powerful tool to discover protein expression signatures in larvae treated with
different antifouling compounds and natural cues. We have also discovered remarkable
differences in larval proteome between developmental stages within a species, and between
species. In this presentation I will highlight our major findings, discuss the challenges that we
have been facing, and outline strategies to overcome those challenges.
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Oral
SHOULD I STAY OR SHOULD I GO?: EFFECTS OF ORGANIC MATTER AND
HYDROGEN SULFIDE ON SETTLEMENT AND RESUSPENSION OF SOFTSHELL
CLAM LARVAE (MYA ARENARIA).
Marie-Josee Abgrall1, Gilles Miron2 and Heather Hunt1
1
Department of Biology, University of New-Brunswick, Saint John Campus, New Brunswick, Canada, E2L 4L5;
email of presenting author: Marie-Josee.Abgrall@unb.ca
2
Département de Biologie, Université de Moncton, Campus de Moncton, Nouveau Brunswick, Canada, E1A 3E9
The softshell clam Mya arenaria is an ecologically and commercially important bivalve
species found off the coast of New Brunswick, Canada. Recent declines in landings have been
observed due to closures of clam flats as a result of increasing H2S contamination, usually
correlated with an accumulation of organic matter (OM). In addition to H2S formation, the
bacterial breakdown of OM can deplete the sediment of O2, rendering it unsuitable for larval
settlement. Little is known about how softshell clam larvae respond to an increasing amount
of H2S and OM in the sediment and whether their settlement or resuspension rate are affected,
leading to possible important post-settlement losses.
To provide a better understanding of how sediment geochemistry may affect settlement and
resuspension of M. arenaria larvae and to determine whether high OM and high H2S
concentrations in the sediments have detrimental effects on them, two series of experiments
were conducted in a flume tank, under three different flow regimes. First, two separate
controlled experiments examining resuspension rate of competent larvae were conducted,
exposing larvae to four concentrations of organic matter and four concentrations of H2S to
establish the tolerance range and effects of these compounds.
Preliminary data show that at all flow speeds, resuspension rate of larvae tended to be higher
when exposed to intermediate and high concentrations of H2S, and to very low and very high
concentrations of OM. Resuspension rate was significantly reduced in sediment containing <1
µM H2S. Burrowing depth appeared to be shallower and burrowing rate tended to be slower at
higher concentrations of H2S and OM. The same trends were observed during the second
series of experiments, involving settlement preferences, in which larvae appeared to avoid
settling on sediment with high concentration of H2S, and very low and very high
concentrations of OM. These preliminary data suggest that softshell clam larvae may actively
settle in relation to sediment geochemistry.
SETTLEMENT PROCESSES OF LARVAE AND JUVENILE GREEN-LIPPED
MUSSELS, NEW ZEALAND
Andrea C. Alfaro
School of Applied Sciences, Faculty of Health and Environmental Sciences, Auckland University of
Technology, School of Private Bag 92006, Auckland 1142, New Zealand; email: andrea.alfaro@aut.ac.nz
One of the most important aspects of mussel life styles is their ability to secrete strong byssal
threads and attach to a variety of surfaces. At the same time, mussel larvae and juveniles are
highly mobile, continuously attaching and re-attaching until a suitable recruitment site is
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Oral
secured. A variety of physical and chemical cues appear to modulate their early behavior,
which sometimes results in complex primary and secondary settlement patterns. For the New
Zealand green-lipped mussel (Perna canaliculus), settlement and recruitment processes are of
crucial importance, since wild-caught spat (still attached to filamentous macroalgae) comprise
about 80% of the seed requirements for this country’s mussel farms. A series of field and
laboratory studies were carried out to elucidate the contribution of physical, chemical, and
behavioral components in the settlement processes of P. canaliculus. Dredged and beach-cast
samples were used to identify the relationship between early mussel (abundance and size) and
morphologically distinct macroalgal substrates. Results from these studies showed a mussel
size-specific association with filamentous structures of various degrees of branching, which
appears to modulate dispersal and retention processes. Laboratory experiments to test the
settlement and attachment strength of early mussels resulted in significant effects of water
flow, air bubbles, and oxygen concentration. Physical and chemical cues on early settlement
processes were tested in laboratory experiments using a variety of natural and artificial
filamentous substrates, and agar plates containing algal extracts. Results indicate the
importance of both physical structure and chemical composition in the settlement process of
P. canaliculus. The overall findings of these multi-disciplinary studies are discussed with
regard to their importance to this growing global aquaculture industry.
ARE LARVAL SETTLEMENT AND EARLY POSTSETTLEMENT MORTALTY OF
INTERTIDAL BARNACLES INFLUENCED BY SOLAR UVR?
Louis A. Gosselin1 and Lisa A. Jones2
1
Dept. of Biological Sciences, Thompson Rivers University, 900 McGill Rd, Kamloops BC, Canada V2C 5N3;
and Dept. of Biology, University of Victoria, Victoria, Canada; email of presenting author: lgosselin@tru.ca
2
Dept. of Biology, Redpath Museum, McGill University, 859 Sherbrooke St. West, Montreal QC, Canada H3A
2K6
Solar ultraviolet radiation (UVR) has been suggested as a potentially important cause of
mortality among larval and early juvenile marine invertebrates, and especially so in intertidal
habitats where marine organisms experience the highest levels of UVR. We studied the
intertidal barnacle Balanus glandula to determine if cyprid larvae settle preferentially under
low-UVR conditions, and also to determine the influence of UVR on larval mortality from
settlement to metamorphosis and on early juvenile mortality during the days immediately
following metamorphosis. This field experiment was carried out in Barkley Sound on the west
coast of Vancouver Island, Canada. Treatments consisted of light-filtering disks permanently
fastened above rock surfaces in the mid-intertidal zone, resulting in some surfaces being
exposed to visible light and UVR, and other surfaces exposed only to visible light (no UVR).
Rock surfaces under the filter disks were monitored daily: all settling cyprids were
individually mapped and their fate was then monitored daily. We also monitored ambient
UVR intensity throughout the experiment. Settlement was unrelated to ambient UVR
intensity. In addition, although mortality rates of settled larvae and early juveniles was high,
UVR was not a major cause of mortality in either stage. UVR does not appear to be an
important factor influencing settlement or survival through the early postsettlement period in
intertidal barnacles.
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Oral
PARASITIC MICROCRUSTACEANS OF THE CLASS TANTULOCARIDA,
EXTERNAL AND INTERNAL MORPHOLOGY OF LARVAE, DEVELOPMENT
AND LIFE CIRCLE.
Gregory A. Kolbasov
Moscow State University, Biological Faculty, White Sea Biological Station, 119992, Moscow, Russia; email:
gakolbasov@gmail.com
The tantulocaridans represent tiniest exoparasites of other benthic crustaceans. They have a
unique life circle among crustaceans characterized with absence of true subsequent molts. The
material on two tantulocarid species including different instars was collected at the White Sea
during 2004-2007. These are Arcticotantulus pertzovi parasite of the harpacticoid genus
Pseudobradya sp. and a new species of family Microdajidae parasite of the tanaid genus
Typhlotanais sp. Additionally, a material on a new species of the family Basipodellidae (a
tantulus larva) from deep-sea of Indian Ocean has been examined. The morphology of
tantulus larva, «parthenogenetic female» and male was studied with SEM and TEM. Both
larval cephalon of tantulus and cephalothorax of male lack the lattice organs, representing a
synapomorphy for the class Thecostraca. Stylet, a funnel-shaped organ and rudimental, closed
cuticular gut were observed inside the cephalon of larva. Stylet is covered by several layers of
thick cuticle, hollow at base, at least, and situated within special chamber inside the gut. A
funnel-shaped organ lies inside an own chamber above the gut, and having a separate opening
above mouth aperture. A tip of funnel-shaped organ ends with dense cuticle. Four canals or
peculiar cavities putatively of secretory nature open into a funnel-shaped organ. They may
produce special cement glues a tantulus to host. Probably, a gut of tantulus penetrates inside a
host through a puncture made with stylet.
THE ROLE OF FLOW IN SETTLEMENT AND HABITAT SELECTION BY
POSTLARVAL AMERICAN LOBSTER
Ashlee Lillis and Paul V. R. Snelgrove
Ocean Sciences Centre & Department of Biology, Memorial University of Newfoundland, St. John’s, NL,
Canada A1C 5S7; email of presenting author: alillis@mun.ca
Following planktonic larval development, American lobster postlarvae seek out appropriate
settling grounds in which to develop through a shelter-restricted juvenile phase. Lobster
postlarvae have been shown to display strong directional swimming ability, distinct bottomsearching behaviours, and clear responses to physical and chemical cues. However, nearly all
experiments performed on larval and postlarval lobster have been done in still water, and little
is known on the effect of hydrodynamics on the settlement process. Flume experiments were
conducted to investigate the effect of flow on postlarval swimming behaviour and settlement.
In a moderate flow (~10 cm/s), postlarvae performed significantly fewer dives and exhibited
fewer searching behaviours than postlarvae in still water. In 1-hour settlement trials,
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Oral
postlarvae were significantly more likely to settle in flow than in still water. In flow,
postlarvae were observed to encounter the substrate more quickly than those in still water
either by actively swimming down immediately in the presence of flow or through largely
passive transport into the cobble by bottom turbulence. The flow environment has an effect on
settlement frequency by increasing encounter rates through both passive deposition and the
modification of postlarval settlement behaviour. These results also suggest that the flows
associated with different benthic environments and their variability (e.g. tidal phase) are
important to consider as potential cues for habitat selection by lobsters at settlement.
SOUND AS AN ORIENTATION CUE: EVIDENCE FROM LARVAL REEF FISH
AND DECAPODS
C. A. Radford1, A. G. Jeffs1, C. T. Tindle2 and J. C. Montgomery1
1
Leigh Marine Laboratory, University of Auckland, PO Box 349, Warkworth 0941, New Zealand; email of
presenting author: c.radford@auckland.ac.nz
2
Department of Physics, University of Auckland, Private Bag 92019, Auckland Mail Center, Auckland 1142,
New Zealand
Many reef fish and decapods have a pelagic larval phase followed by settlement back onto the
reef. Processes influencing settlement can have considerable impact on the demographics of
reef populations. The larval stages of many of these reef organisms have been shown to have
significant swimming abilities which would allow them to reach reefs from hundreds of
meters, if not kilometres, away if a reliable orientation cue was available. Underwater sound
generated on reefs has many characteristics that make it a suitable orientation cue for pelagic
larvae. A wide range of larval reef fishes and decapods have now been found to orient to reef
sound in a manner that is entirely consistent with then using it as a reliable guide towards
settlement habitat. A diverse series of field experiments including light-trap catches enhanced
by replayed reef sound, in situ observations of behaviour, and artificially enhanced settlement
on patch reefs with artificial sources of sound, collectively provide compelling evidence that
sound is used as an orientation cue by these settling pelagic larval stages. Our challenge now
is to begin to measure the importance of underwater sound in the settlement and recruitment
of reef fish and decapods.
SETTLEMENT BEHAVIOUR AND EARLY POST-SETTLEMENT PREDATION OF
THE SEA URCHIN STRONGYLOCENTROTUS DROEBACHIENSIS
Robert E Scheibling1 and Mark C Robinson
1
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1; email of presenting
author: rescheib@da.ca
We examined behaviour of competent larvae of the green sea urchin Strongylocentrotus
droebachiensis provided with pebbles encrusted with coralline red algae, a strong settlement
inducer, in laboratory experiments. Larvae settled at greater frequencies on upward-facing
coralline surfaces and in small gaps between coralline and glass surfaces than expected by a
8th Larval Biology Symposium
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Larval Settlement: cues, behaviour response and
possible mechanisms
Oral
random distribution of settlement. These patterns may be explained by encounter rate with
inductive cues. There was no change in settler distributions within ~1 week of settlement,
indicating no net movement between adjacent microhabitats. In flow, live and recently killed
larvae settled or were passively entrapped at greater frequencies on high- than low-rugosity
coralline crusts. Recent settlers (0.5-1 mm diameter) were consumed by small decapod
crustaceans and bulldozed by periwinkles. Juveniles became less vulnerable to predation by
hermit crabs with increasing size, and reached a growth refuge at ~10 mm. Our laboratory
findings suggest that the cryptic distribution of recent settlers is probably not due to
microhabitat selection by settling larvae or early post-settlement migration, at least not in
response to physical cues such as light or surface texture. Differential rates predation of young
juveniles between exposed and cryptic habitats cannot be ruled out as an important
determinant of this pattern.
LARVAL SETTLEMENT AND “CARRY-OVER EFFECTS” OF LARVAL HISTORY
ON POST-SETTLEMENT GROWTH VARY WITH MACROALGAL HABITAT
COMPOSITION FOR A TEMPERATE REEF FISH
Anna C. Smith 1, Jeffrey S. Shima 2 and Russell G. Cole 3
1, 2
School of Biological Sciences, Victoria University of Wellington, PO Box 600, Kelburn, Wellington, New
Zealand; email of presenting author: anna.smith@vuw.ac.nz
3
NIWA, P O Box 893, Nelson, New Zealand.
Many marine organisms undergo a series of habitat shifts after settlement. Larval reef fish
may settle preferentially into juvenile “nursery habitats” that serve as refuges from predation
and/or increase potential food resources. The likelihood of colonisation and the benefits
afforded by nursery habitats, however, may depend upon larval traits (e.g., size and condition
at settlement), which can affect post-settlement survival and growth via “carry-over effects”.
Over two settlement seasons we conducted manipulations of subtidal benthic macroalgae on
the coast of central New Zealand and quantified demographic rates and analysed larval traits
using otolith microstructure of settling common triplefins (Forsterygion lapillum). F. lapillum
is a small temperate reef fish, whose larvae settle into patches of a variety of shallow subtidal
macroalgae and appear to exhibit a behavioural preference for certain algal species. We
constructed an experimental array of habitat patches at two sites and used these to identify
patterns of settlement and variation in larval traits among macroalgal habitat types. In a set of
complementary experiments we followed the fates of tagged juveniles on experimental habitat
patches to quantify post-settlement growth, survival, and variation in carry-over effects. Postsettlement growth was strongly correlated to late larval growth (up to 10 days prior to
settlement) across all habitat treatments, but strength of this correlation was habitat
dependent. We also found evidence for selective mortality operating on specific larval traits
that was heterogeneous among habitat treatments and between our two focal study sites. The
quality of nursery habitats is often evaluated using measures of post-settlement growth and
survival, but our results suggest these demographic rates may be reshaped by “carry-over
effects” that are themselves dependent upon habitats. Thus, the relative importance of nursery
habitats may depend upon larval traits; habitat quality may modify the underlying relationship
between larval history and post-settlement growth and survival.
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Oral
IDENTIFICATION AND QUANTIFICATION OF CHANGES IN THE
PHOSPHORYLATION STATE OF LARVAL PROTEOME IN RESPONSE TO
SETTLEMENT INDUCTIVE/INHIBITORY CUES
V. Thiyagarjan and Pei-Yuan Qian
Department of Biology & Coastal Marine Laboratory, The Hong Kong University of Science and Technology,
Hong Kong SAR; email of presenting author: vtraj@ust.hk
Competent larvae of several marine invertebrates respond (attach or not to attach) to
settlement cues within several seconds or minutes. In most such cases, response arises without
genetic
transcription
or
translation
and
most
likely
involves
protein
phosphorylation/dephosphorlation. Among the numerous types of post-translational protein
modifications, phosphorylation is well known to play a key regulatory role in many marine
invertebrate larvae such as signal transduction. A fluorescent phosphorylation sensor
technology, referred to as Pro-Q Diamond dye, has been developed that facilitates sensitive
high-throughput analysis of protein and peptide phosphorylation in larval proteome (i.e. entire
complement of proteins expressed by whole larval body). Multiplexed Proteomics technology
(combination of Pro-Q Diamond with SYPRO Ruby dye) permitted us to quantify the
changes in the phosphorylation state of larval species in response to settlement cues. In the
end, the identification of the phosphoproteins is achieved by tandem mass spectrometry.
Application of these rapidly developing molecular techniques in larval settlement studies to
assay phosphorylation state of larval proteome has the potential to provide a wealth of
information about larval settlement mechanism and the mode of action of chemical cues.
Accordingly to our comparative larval phosphoproteome study, the metamorphosed bugula
(B. neritina) larvae had only about 45 phophorylated proteins whereas about 61 and 54
phosphoproteins were detected in newly hatched and antifouling compound-challenged
larvae, respectively. In barnacle (Balanus amphitrite) cyprids, on the other hand, about 87, 85
and 91 phosphorylated proteins were detected in un-attached, antifouling compound
challenged and metamorphosed cyprids, respectively. Most importantly, 3 abundantly
expressed proteins were dephosphrylated during cyprid attachment. The inhibitory cues keep
these 3 proteins at phosphorylated state but prevent the phosphyrylation of as many as 5 to 10
proteins in both barnacles and bugula. To our knowledge, this represents the very first study
demonstrating that quantitative changes in the phosphorylation state of larval proteins
involved in larval attachment and metamorphosis. I also discuss about other applications and
pitfalls of phosphoprteome analysis in larval studies.
A MOLECULAR ANALYSIS OF HYDROIDES ELEGANS METAMORPHOSIS
H. Wang and PY. Qian
Department of Biology & Coastal Marine Laboratory, The Hong Kong University of Science and Technology,
Hong Kong SAR; email of presenting author: wangho@ust.hk
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Oral
Hydroides elegans is a common marine fouling organism in subtropics. Its life cycle includes
a planktonic larval stage in which swimming larvae normally take 5 days to attain
competency for settlement and metamorphosis. Larval settlement is crucial and marks the
beginning of its benthic life, however, almost nothing is known for the endogenous molecular
mechanism in this process. In this study, a PCR based subtractive hybridization library was
constructed using day-4 incompetent larvae as a driver and day-5 competent larvae as a tester.
Among the transcripts we isolated from the library, 20 transcripts showed significant matches
to proteins in the GenBank. Particularly, one transcript matched p38 mitogen-activated
protein kinase, indicating possible involvement of p38 MAPK signal transduction pathway in
the larval settlement and metamorphosis. To test this hypothesis, larvae were treated with a
p38 MAPK inhibitor, SB203580, and results showed that the inhibitor significantly inhibited
larval settlement of H. elegans with an EC50 of 5uM.This study provided information about
the genes involved in H. elegans larval competency and preliminary evidence to support the
hypothesis of possible involvement of p38 MAPK pathway in H. elegans settlement and
metamorphosis.
SETTLEMENT CUES FOR THE GREEN LIPPED MUSSEL
Tim J. Young, Andrea C. Alfaro and John Robertson
School of Applied Sciences, Faculty of Health and Environmental Sciences, Auckland University of
Technology, Auckland, New Zealand; email of presenting author: timyou92@gmail.com
The native green lipped mussel, Perna canaliculus, is a commercially important species for
New Zealand. Current methods of spat collection involve harvesting natural stocks, although
in recent years there has been a move towards hatchery production. At a suitable larval age,
juveniles are seeded onto artificial substrates where their retention is highly variable. The
factors responsible for this settlement variability are still largely unknown, although physical
and chemical cues are thought to be of critical importance. In wild populations, larvae remain
planktonic for up to 6 weeks after which they undergo primary settlement. This involves
attachment to specific substrates, which may be largely controlled by chemical cues.
However, the specific chemicals involved in this process, and the mechanisms by which they
act as attractants to mussel larvae are not known.
In order to investigate possible mechanisms of signal transduction in P. canaliculus, the
effects of neuroactive chemicals on settlement behaviour were investigated. Veliger larvae
were exposed to a range of compounds, and important components of the signal transduction
mechanism have been identified.
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Poster
LARVAL METAMORPHOSIS IN THE INVASIVE SPECIES
FORNICATA: FROM BIOASSAYS TO GENOMIC TOOLS
CREPIDULA
Catherine Dreanno1, Thierry Comtet1, Arnaud Tanguy1, Régis Lasbleiz1,2, Jan
Pechenik3, Isabelle Guisle-Marsollier4 and Frédérique Viard1
1
Lab. Adaptation & Diversité en Milieu Marin (UMR 7144 CNRS UPMC), Station Biologique de Roscoff,
place Georges Teissier BP74, 29682 ROSCOFF cedex, France; email of presenting author: viard@sb-roscoff.fr
2
Service Mer & Observation (FR 2424 CNRS UPMC), Station Biologique de Roscoff, place Georges Teissier
BP74, 29682 ROSCOFF cedex, France
3
Biology Department, Tufts University, Medford, Massachusetts 02155, USA
4
Institut du Thorax, INSERM U915, 1 Rue Gaston Veil, BP 53508, 44035 Nantes Cedex 1, France
Following its human-mediated introduction at the end of the 19th century, the American
gastropod Crepidula fornicata has colonized many European bays and estuaries. A
comprehensive understanding of the processes acting on larval metamorphosis is required to
examine its ability to spread and implement management strategies. In this context,
multidisciplinary approaches are needed. Population genetics, modelling and in situ surveys
have shown that larval dispersal for this species is very efficient at both local and regional
levels. We have now conducted laboratory experiments and developed genomic tools in order
to better understand the processes involved in metamorphosis of this species, and especially
the role of chemical cues. We first carried out a series of assays to analyze the kinetics and/or
intensity of metamorphosis in response to both chemical cues found in situ (dibromomethane,
a halogenated compound) and protein extracts from adults. Both were shown to stimulate
metamorphosis as efficiently as excess KCl, the standard tool for inducing metamorphosis in
this species. Moreover, the halogenated compound triggered metamorphosis very rapidly, i.e.
in less than one hour. This compound is of interest as it might be released by red algae found
as an epibiont on the shell of C. fornicata adults. We have also studied the effects of these
several cues on gene expression during larval development. cDNA microarrays were
constructed with about 2800 genes, among which only 4% were recovered in databases. The
responses of differentially expressed genes as revealed by microarray analyses were then
assessed using real time PCR. Regulation profiles of these specific transcripts are discussed
with regards to the ontogenesis of C. fornicata.
PURIFICATION OF THE WATERBORNE SETTLEMENT PHEROMONE-LIKE
PROTEIN FROM THE ADULT BARNACLE EXTRACTS
N. Endo1, Y. Nogata1, K. Matsumura2 and E. Yoshimura2
1
Central Research Institute of Electric Power Industry, Abiko, Ciba, Japan; email of presenting author: nendo@criepi.denken.or.jp
2
CERES, Inc., Chiyoda-ku, Tokyo, Japan
Two types of settlement pheromones, substratum-bound and waterborne, are known to play
an important role in the larval settlement process of gregarious barnacles. Several studies have
been conducted to examine chemical structure of these pheromones. A glycoprotein, SIPC,
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Poster
consisting of 76, 88, and 98 kDa subunits was purified as one of the substratum-bound type,
and the primary structure was determined by cDNA cloning. On the other hand, little
information has been obtained for the waterborne pheromone. In the present study,
waterborne pheromone-like protein was purified from the gregarious barnacle, Balanus
amphitrite and its N-terminal amino acid sequence was determined. Whole body of the adult
barnacles was homogenized with Tris-HCl buffer. Homogenate was centrifuged, and
supernatant was applied to gel-filtration column chromatography. The column eluate was
monitored for protein, and also for larval settlement inducing activity by the assay using 24well polystyrene plate as follows. Each fraction and 7 to 10 cypris larvae were added to a well
filled with filtered natural seawater at final volume of 1.0 mL. Number of settled larvae was
counted after the incubation for 3 h at 25ºC. Fractions showing settlement inducing activity
were pooled, and were subjected to ion exchange and hydroxyapatite column chromatography
for further purification. Almost 90% of cypris larvae settled in the presence of the purified
protein at 10 µg/mL. The result of SDS-PAGE indicated that relative molecular mass of the
protein in reduced and denatured form is 32 kDa. Then, N-terminal 33-residue sequence of
the intact protein was determined, and homology search was conducted with
EMBL/Genbank/DDBJ databases. The sequence of the protein obtained in the present study
showed no similarity with previously reported proteins. Therefore, we may find a new
pheromone-like protein inducing larval settlement of barnacles.
FIELD EXPERIMENTS ON LARVAL SETTLEMENT INDUCING EFFECTS OF
CRUDE EXTRACTS OF THE BARNACLE MEGABALANUS ROSA
Y. Nogata1, K. Matumura2, E. Yoshimura2, K. Sato2, N. Endo1, A. Dazai3, O. Abe3, and
I. Sakaguchi1
1
Central Research Institute of Electric Power Industry, 1646, Abiko, Abiko-shi, Ciba, 270-1194, JAPAN;
email of presenting author: noga@criepi.denken.or.jp
2
CERES, Inc., 1-6-1 Ogawa-cho, Chiyoda-ku, Tokyo, 101-0052, JAPAN
3
Shizugawa Nature centere, 40, Sakamoto, Togura, Minamisanriku, Miyagi, 986-0781, JAPAN
In barnacle, cypris larva is specialized to search suitable surfaces for settlement and has
unique searching behaviour. The cyprid behaviors and gregarious phenomena are affected by
not only several environmental factors (e.g. light, temperature, salinity, and surface type) but
also chemical stimulations, such as SIPC (sttlement-inducing protein complex) and
waterborne pheromone, from adult barnacles. In this study, we examined whether chemical
cues from adult barnacles induce gregarious settlement of the barnacle Megabalanus rosa,
which is major fouling species at electric power stations in Japan, in the field conditions.
Field experiments using crude extracts of adult barnacles were carried out at Shizugawa bay,
Miyagi, Japan. Whole adult body of the two barnacles species, con-specific Megabalanus
rosa and allo-specific Balanus amphitorite were cruched with 50mM Tris-HCl buffer and the
homogenates were centrifuged. The resultant supernatants were prepared to 1mg protein/ml,
and 0.2mg protein equivalent was applied onto 16 places of 48 concave wells (1cm diameter)
in slate plate (20cm x 20cm, total 48 concave wells) on PVC plates, then the treated test plates
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Poster
were suspended with untreatment plates (control) at a depth of 3.0m for certain days (4days37days). After the test period, barnacles which settled on the plate’s surface were counted.
When adult extracts were applied onto slate plates, barnacles dominantly settled on their
surface in comparison with control surface. Settlement was thought to be induced by both
con- and allo-specific supernatants. These results suggest that settlement pheromones
contribute gregarious settlement in barnacles not only in the laboratory but also under field
conditions.
DEVELOPMENTAL EVENTS DURING SETTLEMENT AND METAMORPHOSIS
OF BALANUS IMPROVISUS CYPRIDS USING SEM
Alireza Sari1 and Jens T. Høeg2
1
School of Biology, College of Science, University of Tehran, Tehran, IRAN; email of presenting author:
sari@khayam.ut.ac.ir
2
Department of Cell Biology and Comparative Zoology, Biological Institute, University of Copenhagen,
Copenhagen, DENMARK , jthoeg@bi.ku.dk
Metamorphosis represents an especially critical series of events for barnacle cypris larvae.
Following settlement they must change their cypris carapace into the armour of shell plates of
the juvenile barnacle and remodel most of their internal structure. This complicated
morphological change takes place while the metamorphosing cyprid is under severe time
pressure and attached only by the fragile cypris antennules We have used scanning electron
microscope on an accurately timed series of developmental stages to study the changes in
external morphology during cypris-juvenile metamorphosis in balanomorphan barnacles. We
used larvae of Balanus improvisus from a Caspian Sea population reared to cyprids in batch
cultures in the laboratory. Cyprids were transferred to polystyrene beakers for settlement and
each settled cyprid was monitored for morphological changes from cypris to juvenile by
fixing specimens for SEM at appropriate time intervals. After choosing the proper settlement
position and secretion of cypris cement, the cyprids assumed a position with dorso-ventrally
flattened carapace valves. Each valve shows muscle marks dorsally and revealed ongoing
internal activity indicating the ongoing moulting process. During metamorphosis, some long
setae were observed both on the external and internal cuticle, and they seemed to belong to
juvenile developing within the cyprid carapace. These setae may act as a means of contact
with environment during the transitional stage to the juvenile barnacle. Mechanical
attachment of the vestigial peduncle to the substratum by cuticular projections and anchoring
cuticular threads (not setae) are an effective supplementary adhesive mechanism during early
attachment prior to basal calcification and development of the adult cement apparatus.
Moving cirri appeared very early in the juvenile but had few segments, while later stages
developed annulated cirri bearing many long setae. In next developmental stage the juveniles
developed four primordial shell plates, while the primordia of the carino-lateral plates
developed slightly later. The results of the present study provide new detailed information on
the morphological changes during early sessile life in barnacles.
8th Larval Biology Symposium
Lisbon, 2008
Larval Settlement: cues, behaviour response and
possible mechanisms
Poster
A MASSIVE SETTLEMENT EVENT OF PATELLID LIMPETS IN ARTIFICIAL
TIDEPOOLS (SINES, SW PORTUGAL)
Maria Ines Seabra123, Teresa Cruz134, David Jacinto13, Joana Fernandes13, Cristina
Espirito-Santo1, João J. Castro134and Stephen J. Hawkins25
1
Laboratório de Ciencias do Mar, Universidade de Evora, Apartado 190, 7520-903 Sines, Portugal; email of
presenting author: iseabra@uevora.pt
2
The Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, PL1 2PB,
Devon, UK
3
Centro de Oceanografia, Faculdade de Ciencias da Universidade de Lisboa, Lisboa, Portugal
4
Departamento de Biologia, Universidade de Évora, Évora, Portugal
5
College of Natural Sciences, Bangor University, Bangor Gwynedd, LL57 2UW, Wales, UK
The Port of Sines, located in the SW coast of continental Portugal, is a deep oceanic port with
international importance. Outside the port, limpet species are abundant on rocky shores,
namely Patella ulyssiponensis, P. depressa and Siphonaria pectinata. In these shores,
juvenile limpets are more abundant in tidepools and damp/shaded microhabitats. In contrast,
inside the port, almost all rocky shores are breakwaters with artificial blocks or big boulders
where tidepools and small crevices are very scarce and limpets (both adults and juveniles) are
much less abundant. We tested the hypothesis of different patterns of settlement of limpets in
two locations: a natural shore outside the port and an artificial shore inside the port.
Settlement of limpets was measured in small artificial tidepools deployed at these locations
from February to April 2005.
Early benthic-stage Patellid limpets (postlarval individuals with protoconch) were found in all
artificial tidepools deployed on both locations and their maximum density was up to 20 ml-1.
Regarding the size of settlers (200-500 μm in maximum length of developing adult shell),
their post-settlement age was estimated to range from c. 2 to 12 days. Those results suggest
that the differences in the abundance of limpets found inside and outside the port are not
caused by constrains on larval supply but most likely by the scarcity of suitable microhabitat
for limpet settlement inside this port and/or by putative higher post-settlement limpet
mortality inside this port.
Similar experiments were carried out during 2005, 2006 and 2007, but no other event like this
was observed. Limpet settlement in artificial tidepools was nil, although tri-monthly
recruitment of limpets in natural tidepools was observed inside and outside the port.
This kind of massive event and the observation of patellid settlers in nature have been rarely
described in the literature.
Lisbon, 2008
8th Larval Biology Symposium
Larval feeding strategies
Plenary
PLANKTOTROPHY AND LECITHOTROPHY DURING EARLY LARVAL STAGES
OF DECAPOD CRUSTACEANS - ECOLOGICAL ASPECTS AND THEIR
RELEVANCE FOR AQUACULTURE
R. Calado
1
CESAM and Department of Biology of the University of Aveiro, Campus Universitário de Santiago, 3810-193
Aveiro, Portugal; email: rjcalado@ua.pt
The availability of suitable planktonic preys is a limiting factor for the survival of larval
organisms in the pelagic environment. The larvae of decapod crustaceans are no exception to
this rule and must be able to capture, ingest and digest suitable preys in order to survive and
metamorphose. However, developing larvae commonly have to endure variable periods of
starvation due to the temporal and/or spatial patchiness of planktonic food. Although most
decapod larvae are planktotrophic and require planktonic food to survive, various degrees of
lecithotrophy have also evolved among some species, significantly reducing their nutritional
vulnerability at hatching. Larvae displaying lecithotrophic development fulfill their nutritional
requirements through the catabolization of endogenous reserves. When those reserves result
from remaining parts of the maternal egg yolk this phenomenon is termed primary
lecithotrophy. While largely enhanced endogenous reserves allow larvae to undergo complete
larval development in the absence of food (termed full or obligatory lecithotrophy),
moderately enhanced reserves only allow larvae to develop through a certain number of stages
in the absence of food. As an example, larvae may be able to molt to the second zoeal stage in
the absence of food, with subsequent larval stages being planktotrophic. Additionally, these
larvae commonly retain their ability to capture and ingest preys during the first zoeal stage
(facultative primary lecithotrophy - FPL). The existence of FPL in some decapod species has
promoted the erroneous belief among researchers working in aquaculture that starving newly
hatched larvae until they have reached the second zoeal stage was an innocuous practice that
would not affect the success of culture trials. Nonetheless, recent studies have clearly
demonstrated that such practice seriously affects the ability of later zoeal stages to
metamorphose and that, even in species displaying partial lecithotrophy, the exposure to
starvation periods always promotes deleterious effects.
NUTRITION IN MARINE INVERTEBRATE LARVAE: SPECIAL EMPHASIS ON
THE ECHINODERMS
Sophie George
Biology
department,
Georgia
georges@georgiasouthern.edu
Southern
University
Statesboro
Georgia
USA;
email:
Phytoplankton of various sizes and shapes are the main food source for many marine
invertebrate larvae. The mere presence of food in abundance does not guarantee successful
larval development to metamorphosis. Larvae must be able to capture particles, ingest and
8th Larval Biology Symposium
Lisbon, 2008
Larval feeding strategies
Plenary
digest them. Most marine invertebrate larvae feed by sieving, filtering, actively responding to
particles or using a combination of these feeding mechanisms. Some marine invertebrate
larvae experience difficulties ingesting small algal cells or when ingested, have difficulties
digesting the cells because of their thick cell walls. At low algal concentrations, clearance
rates are typically maximal and ingestion rates are proportional to food concentration. At high
concentrations, clearance rates decline and ingestion rates are maximal. In many cases, larvae
stop feeding at extremely high concentrations.
An alga could be a poor food source even though it is ingested, digested and does not appear
to produce toxins. It could simply be lacking an essential nutrient required for larval growth
and development. For example, the small alga Isochrysis galbana has the highest percentage
of the monounsaturated fatty acid oleic acid and long chain polyunsaturated fatty acid (PUFA)
docosahexanoic acid (DHA). Dunaliella tertiolecta an intermediate-sized alga has the highest
percentage of linolenic acid (LNA) but trace amounts of long chain PUFA. A slightly larger
alga cell Rhodomonas sp., has the highest percentage of stearidonic (SDA) and long chain
PUFA eicosapentanoic acids (EPA). Recent studies have revealed that mixed algal diets rich
in LNA, SDA and EPA with trace amounts of DHA result in high larval growth and
development rates to metamorphosis for some species but not for others. More studies using
different natural algae that vary in size and biochemical composition might give us insights
into nutrient requirement of marine invertebrate larvae and lead to development of artificial
diets for commercially important species.
8th Larval Biology Symposium
Lisbon, 2008
Larval feeding strategies
Oral
TROPHIC IMPACT AND FEEDING RATES OF MICROPLANKTONIC LARVAE
IN THE NW MEDITERRANEAN COASTS
R. Almeda, M. Alcaraz, A. Calbet, J. Movilla, E. Saiz, V. Saló, R. Simó, I. Trepat and L.
Yebra
Institut de Ciències del Mar (CSIC) Barcelona, Spain; email of presenting author: ralmeda@icm.csic.es
Planktonic larvae are the main components of metazoan microplankton. Holoplanktonic
copepod larval stages, nauplii and copepodites, are the most abundant metazoans in marine
waters. Meroplanktonic larvae are also frequent in coastal waters and, occasionally, may
become the dominant organisms of the metazooplankton microplankton community. Despite
their relevance, microplanktonic larvae have been excluded in most zooplankton studies. This
lack of information may result in underestimating the role of zooplankton in marine food web
dynamics.
We conducted feeding experiments on the microplanktonic larvae community in the NW
Mediterranean along an annual cycle, from September 2005 to September 2006. The
experiments consisted of 24 h incubations of natural sea water with added concentrated
microplanktonic larvae (50-200 µm) as predators. We analyzed the grazing pressure of
microzooplankton on phytoplankton (chlorophyll a), diatoms, nanoflagellates, ciliates, and
dinoflagellates. The trophic impact of metazoan microplankton was calculated as the % of
biomass of the prey standing stock grazed daily.
Copepod nauplii and copepodites were the dominant microplanktonic larvae, except in April
when polychaete larvae were the most abundant group. Microplanktonic larvae grazed on all
the studied prey groups. The highest ingestion rates were on nanoflagellates, except in spring
when diatoms were the main component of micrometazoans diet. Ingestion rates were
positively related to prey biomass, except for nanoflagellates. The trophic impact on total
chlorophyll a was lower than 10 %. When considering chlorophyll a >10 µm fraction, the
trophic impact was higher than on total chlorophyll, particularly during the summer (20-30
%). Despite the high ingestion rates on nanoflagellates, the trophic impact was generally low
(<5 %). Ciliates and dinoflagellates were subjected to the highest trophic pressure throughout
the annual cycle (12 % in average). According to our results, the feeding impact of
microzooplankton larvae on coastal NW Mediterranean marine food webs is quantitatively
more important than that of crustacean mesozooplankton.
LIPID CLASS, FATTY ACID, AMINOACID AND MINERAL PROFILES DURING
LARVAL DEVELOPMENT OF Maja brachydactyla
Mireia Andrés, Alicia Estévez and Guiomar Rotllant
IRTA. Ctra. Poble Nou, Km. 5.5, 43540. Sant Carles de la Ràpita (Tarragona), Spain; email of presenting author:
mireia.andres@irta.es
Changes in lipid class, fatty acid, amino acid (AA) and mineral profiles were studied during
larval development of the spider crab Maja brachydactyla in order to provide information on
its ontogeny and to develop future studies on its larval nutrition. Four independent batches
8th Larval Biology Symposium
Lisbon, 2008
Larval feeding strategies
Oral
were analyzed from hatching to metamorphosis (two zoeas -ZI and ZII-, one megalopa -Mand first juvenile -CI-) under constant culturing conditions (18ºC, 36‰, given enriched
Artemia metanauplii as food). Polar lipids (mainly phospatidyl-choline and phospatidylethanolamine) decreased during larval development and after metamorphosis concomitant
with an increase of neutral reserves (tryacylglycerol and sterol esters/waxes), which
represented a 71.5% of total lipids (TL) in newly hatched ZI and 81.9% in CI. Cholesterol
content was high throughout larval development, decreasing significantly from ZI (29.6±5.7%
TL) to ZII (22.3%±3.0 TL) and remaining within these levels in M and CI. Fatty acid (FA)
profiles changed significantly during development, by means of a decrease of saturated (18:0)
and n-3 highly unsaturated FA (n-3 HUFA, mainly 20:5n-3 and 22:6n-3) and an increase of
monounsaturated FA (mainly 18:1n-9). Polyunsaturated n-6 HUFAs (mainly 18:2n-6)
increased from ZI to M.
Total AA decreased from 40.5 to 30.6% of dry weight (DW) during ontogeny (ZI to CI,
respectively), being the non-essential AA glutamic acid (GLU), alanine (ALA) and glycine
(GLY) the most abundant during larval stages whereas in juveniles GLU, ALA and arginine
(ARG) were the major amino acids. Changes in ontogeny showed a significant increase of
aspartic acid, serine, and ARG, concomitant with a decrease in some other AA, mainly, GLU,
threonine and lysine. Calcium (Ca) was the most abundant mineral during ontogeny,
increasing significantly from larval stages (89.5±6.2 µg Ca·mg-1) to juveniles (173.9±6.5 µg
Ca·mg-1). Magnesium, manganese and strontium increased during ontogeny while potassium,
phosphorus and cupper decreased.
FROM LECITHOTROPHY TO PLANKTOTROPHY: ONTOGENY OF LARVAL
FEEDING IN THE AMAZON RIVER PRAWN, MACROBRACHIUM AMAZONICUM
Klaus Anger1 and Liliam Hayd2
1
Biologische Anstalt Helgoland, Alfred-Wegener-Institut für Polar- und Meeresforschung, 27498 Helgoland,
Germany; email of presenting author: Klaus.Anger@AWI.de
2
Universidade Estadual de Mato Grosso do Sul, 79200-000 Aquidauana, MS, Brazil
In an experimental laboratory study with a population originating from the mouth of the
Amazon River, Brazil, we tested the early larval stages of the prawn Macrobrachium
amazonicum for their dependence on planktonic food sources. As criteria for an uptake and
conversion of food (Artemia nauplii), we measured changes in larval dry mass and elemental
composition (carbon, hydrogen, nitrogen), as well as rates of survival and development.
Experiments conducted with larvae from three different females showed consistently that the
first zoea is a non-feeding stage (obligatory lecithotrophy). While survival and duration of
development through the Zoea II stage were still not affected by absence or presence of food,
fed larvae showed significant growth (indicating facultative lecithotrophy). The third zoeal
stage exhibited still a high level of independence from food, surviving for extended periods
(up to another 11 days, or 15 days from hatching) in complete absence of food. In contrast to
the Zoea II, however, this stage was under conditions of continued starvation no longer
capable to moult the subsequent stage IV (obligatory planktotrophy). In summary, the
ontogeny of larval feeding consists in M. amazonicum of gradual changes from complete
8th Larval Biology Symposium
Lisbon, 2008
Larval feeding strategies
Oral
food-independence (Zoea I), through facultative lecithotrophy (Zoea II), to obligatory
planktotrophy (Zoea III and all later stages). Reduced nutritional vulnerability in the early
larval stages, together with an initial tolerance of freshwater, allows for hatching in
oligotrophic riverine environments and survival during the period of subsequent larval
downstream transport towards estuarine waters, where both average salinity and plankton
productivity are higher.
FOOD SHORTAGE DURING THE MEGALOPA STAGE REDUCES SIZE AT
METAMORPHOSIS AND EARLY JUVENILE GROWTH IN SHORE CRAB,
CARCINUS MAENAS
L. Giménez1 and K. Anger2
1
School of Ocean Sciences, Bangor University, LL59 5AB Menai Bridge, Wales, United Kingdom, email of
presenting author: l.gimenez@bangor.ac.uk
2
Biologische Anstalt Helgoland, Stiftung Alfred Wegener Institut für Polar- und Meeresforschung, 27498
Helgoland, Germany
Environmental conditions experienced by larval stages can affect size, growth and survival
during the juvenile life of marine invertebrates. We studied if food conditions experienced
during the end of the larval development affect the size at metamorphosis and growth during
the first five juvenile stages (J-I-V) of the shore crab, Carcinus maenas. Megalopae were
collected from the field and maintained in the laboratory with or without food (Artemia sp
nauplii) until metamorphosis to the first juvenile stage. The resulting juveniles were fed
thereafter. Prolonged time to metamorphosis in the absence of food resulted in smaller size at
metamorphosis, and juvenile growth rates were significantly reduced when megalopae were
not fed. Effects of larval nutrition were still found at the J-V stage, in spite of 30-40 d of ad
libitum food conditions after metamorphosis. The nutritional history during the larval phase
may be important to explain variability in juvenile survival in C. maenas, if mortality by
cannibalism and predation depends on juvenile size and growth rates.
FEEDING ABILITY OF Carcinus maenas (DECAPODA, BRACHYURA,
PORTUNIDAE) MEGALOPAE SURVIVING PREDATORY INTERACTIONS – IS
THERE A PRICE TO “LIVE ANOTHER DAY”?
Ainhoa O. Olaguer-Feliú1, Ricardo Calado2, Juan Ignacio González-Gordillo1 and
Henrique Queiroga2
1
CACYTMAR (Institutos de Investigación), Campus Universitario de Puerto Real, 11510 Puerto Real - Cádiz –
Spain; email of presenting author: ainhoa.ortega@uca.es
2
CESAM (Centro de Estudos do Ambiente e do Mar), Departamento de Biologia da Universidad de Aveiro,
Campus Universitário de Santiago, 3810-193 Aveiro- Portugal
8th Larval Biology Symposium
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Larval feeding strategies
Oral
Non lethal attacks by predators may severely damage surviving prey. Although some
organisms are able to shed appendages (autotomy) to escape predatory attacks, physical
damage sustained during an encounter with a predator may adversely affect their locomotion
and foraging ability.
The transitional larval stage between planktonic and benthic forms of brachyuran decapods
(the megalopa) is exposed to intra and interspecific predation in both habitats. Despite their
ability to autotomize certain body parts (e.g., chelipeds and pereiopods), there is still no
available data to evaluate the consequences of body damage to their feeding ability.
The aim of our study is to evaluate how (i) light damage (ablation of one cheliped or one fifth
pereiopod), (ii) moderate damage (ablation of both chelipeds or both fifth pereiopods), (iii)
severe damage (ablation of one eye), (iv) extreme damage (ablation of both eyes or one eye
and cheliped) and (v) nearly lethal damage (ablation of both eyes and chelipeds) affects
feeding ability of Carcinus maenas megalopae, using intact specimens as controls.
Intact megalopae displayed average (±SD) feeding rates (%) (71.0±7.1) similar to those with
light and moderate damage, except when missing both chelipeds. Larvae without chelipeds
showed severe (48.8±5.9) damage and like suffering extreme (24.8±11.2) damage displayed
significantly lower feeding rates than intact megalopae. Those with near lethal damage were
only able to ingest a very low number of prey (7.2±6.7). The ability of megalopae with light
and moderate damage to feed at rates similar to undamaged individuals strongly suggests that
the ability to shed an appendage during an aggressive encounter is an important anti-predatory
mechanism. In contrast, severe damage to the eyes and chelipeds will seriously affect survival
ability. By shedding an appendage individuals may, therefore, be able to avoid serious
damage and concomitantly increase their ability to survive.
FEEDING RATES OF EARY STAGE NEPHROPS NORVEGICUS LARVAE
Patricia N. Pochelon1, 2, Ricardo Calado1, Antonina dos Santos2 and Henrique Queiroga1
1
CESAM, Departamento de Biologia, Campus Univeristario Santiago, Universidade de Aveiro, 3810 Aveiro,
Portugal; email of presenting author: ppochelon@ua.pt
2
Instituto Nacional de Recursos Biológicos- IPIMAR, Avenida de Brasilia s/n, 1449-006 Lisbon, Portugal
Norway lobster, Nephrops norvegicus, is a commercially important benthic marine decapod
commonly found on the Atlantic European shelf and the Mediterranean Sea. Due to
differences in the reproductive season, larvae hatching in the Atlantic and the Mediterranean
face different dietary prey availability, ranging from higher food levels to oligotrophic
conditions, respectively. Studies addressing larval feeding in clawed lobsters have highlighted
how early larval feeding influences their development. Due to plankton patchiness,
developing larvae may be exposed to intermittent periods of starvation and/or suboptimal prey
availability. This work investigated the feeding response of zoea I and II of N. norvegicus
under variable prey densities: 0.5, 1, 3, and 5 Artemia nauplii ml-1. Due to the current interest
in larviculture for Norway lobster restocking, the effect of natural (12-h light) and extreme
photoperiods (0-h light and 24-h light) on prey consumption of both zoea I and II was also
evaluated. For both stages a significant increase in the average number (±SD) of consumed
preys was recorded with increasing food levels (from 17,6±2,2 to 122,2±5,3 nauplii and
8th Larval Biology Symposium
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Larval feeding strategies
Oral
17,2±2,7 to 142,8±4,1 for zoea I and zoea II, respectively). This feeding behaviour indicates
that larvae may be able to maximize prey ingestion in the presence of plankton patches with
high food levels and minimize the deleterious effects of intermittent starvation. The absence
of significant differences in the number of ingested preys in both larval stages may be
explained by a suboptimal size of preys offered to zoea II. The small sized nauplii may not
have triggered proper predatory responses in larger larvae. These results seem to indicate that
both prey availability and size play a crucial role in the trophodynamics of developing N.
norvegicus larvae. Extreme photoperiods resulted in lower prey consumption for both larval
stages and their use in larviculture is not recommended.
PREY SELECTION OF LARVAL PLANKTIVOROUS FISH IN THE SAN
FRANCISCO ESTUARY: IMPACTS OF AN INTRODUCED SPECIES
Lindsay J. Sullivan1, Wim J. Kimmerer1, Bradd Baskerville-Bridges2 and Toni R.
Ignoffo1
1
3152 Paradise Drive, Romberg Tiburon Center for Environmental Studies, San Francisco State University,
Tiburon, CA, USA, 92920; email of presenting author: ljswr@sfsu.edu
2
Department of Biology and Agricultural Engineering, University of California, One Shields Avenue, Davis,
CA, USA, 95616
Populations of pelagic fish in the San Francisco Estuary are in a state of decline. Declines in
the abundance of several planktivorous fish have been correlated to changes in both the
abundance and distribution of their zooplankton prey. These correlations provide indirect
evidence that changes in food supply are contributing to the decrease in fish abundance. Over
the past two decades, there has been a shift in the species composition of zooplankton from a
community dominated by calanoid copepods to one dominated by cyclopoid copepods,
particularly the small, introduced Limnoithona tetraspina. In recent years, L. tetraspina has
become the most abundant copepod in the brackish reach of the estuary, at times
outnumbering all other copepods by a factor of ten. Because this introduced copepod is
smaller than the historically dominant calanoid species, the relative contribution of these
groups to the total zooplankton biomass differs greatly. This difference in carbon content may
however be offset by the high numerical abundance of L. tetraspina. We quantified the
relative consumption of the different copepod groups by larval delta smelt (Hypomesus
transpacificus) and striped bass (Morone saxatilis) in the San Francisco Estuary using
laboratory feeding experiments. Prey selection was correlated to prey size and dependent on
life history stage of both the predator and prey. Although larval fish can consume L.
tetraspina, the peak abundance of this copepod occurs after the larval period of delta smelt
and several other fish species. Information on the differential consumption of prey and the
mechanisms that control it will help determine how changes in the prey assemblage translate
into population success of planktivorous fish. In addition, information on diet and prey
selection will lead to a better understanding of how these species will respond to new
predators, competitors, or prey.
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Poster
ECOPHYSIOLOGY OF PLANKTONIC
POLYCHAETA Polydora ciliata.
LARVAE
OF
THE
SPIONID
Rodrigo Almeda1, T. M. Pedersen2, H. H. Jakobsen3, M. Alcaraz1, A. Calbet1 and B. W.
Hansen2.
1
Institut de Ciències del Mar (CSIC), Barcelona, Spain; email of presenting author: ralmeda@icm.csic.es
Roskilde University, Roskilde, Denmark.
3
Danish Institute for Fisheries Research, Charlottenlund, Denmark.
2
Polydora ciliata is one of the more common benthonic invertebrate in Danish coastal
environments with dense local population, often indicating organic pollution. Their pelagic
larvae are very frequent, and occasionally may become the dominant metazooplankton in
coastal waters. We carried out field and laboratory studies to evaluate aspects of feeding,
growth and ecology of P. ciliata larvae.
One of the aims of this study was to determinate if the natural populations of P. ciliata larvae
are food limited. The study site was Søminestationen, in the Isefjord, characterized by low
depth, muddy bottom sediments and eutrophic waters with high chlorophyll concentrations.
The larval abundance of P. ciliata and food availability were estimated regularly from May to
November. In the laboratory, larvae were incubated under two different food rations: natural
sea water (control treatments) and natural sea water with added Rhodomonas salina culture ad
libitum (enrichments treatments).
Additional laboratory experiments were conducted to assess larval feeding efficiency vs.
particle size, ingestion and growth rates of P. ciliata larval stages as a function of food
concentration, as well as their gross growth efficiency.
P.ciliata larvae were present throughout the study period and sometimes were the dominant
metazooplankter (more than 60 % of total metazooplankton biomass).
In situ specific growth rates were significantly higher in the enriched treatments than in
controls, with average ± SD values of 0.215 d-1 ±0.06 and 0.107 d-1± 0.03 respectively. In
natural conditions, during the study period, we did not find saturating food concentrations.
The optimum prey size changed along the larval development, from 12 µm in early stages to
19-53 µm in late stages. All studied larval stages showed a type II functional response (Ivlev
equation). The average maximum specific ingestion rates feeding on Thalassiosira weissflogii
and Rhodomonas salina were 0.40 d-1 and 0.46 d-1, respectively. The food saturation level was
reached at around 1.5 µg C ml-1.
Average maximum specific growth rate was 0.20 d-1. At saturating food concentrations, the
gross growth efficiencies ranged from 0.47 in early-stages to 0.28 in intermediate and latestages.
Our field and laboratory results show that P. ciliata larvae are functionally food limited and
therefore they do not exhibit maximal rates of growth in natural conditions, despite they
inhabit eutrophic waters.
ABUNDANCE AND FEEDING RATES OF PLANKTONIC LARVAE UNDER
HARMFUL ALGAL BLOOM CONDITIONS OFF VACOUNVER ISLAND.
Rodrigo Almeda1, Amber Messmer2, M. Alcaraz1, A. Calbet1, Louis A. Gosselin2.
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Larval feeding strategies
Poster
1
2
Institut de Ciències del Mar (CSIC). Barcelona, Spain; email of presenting author: ralmeda@icm.csic.es
Thompson Rivers University .Kamloops, Canada.
The composition and abundance of planktonic larvae before and during a bloom of the toxic
Raphidophyceae Heterosigma akasiwo and the dinoflagellate Prorocentrum gracile was
estimated in West coast of Vancouver Island in July 2006.Grazing experiments were also
conducted to evaluate meroplanktonic larvae feeding rates, prey selection and trophic impact
under bloom conditions.
The feeding experiments consisted of bottle incubations of the natural bloom microplanktonic
community with and without the addition of meroplanktonic larvae as grazers. The
incubations were carried out in situ, at 5 m depth for 48 h. The larvae used in the experiments
were Serpula colombiana (polychaeta), Strongylocentratus purpuratus (echinoderma) and
Balanus creanatus (cirripedia) from lab cultures, and several bivalve and gastropod larvae
collected from the study site by plankton tows. Clearance and ingestion rates were calculated
for each prey type according to Frost (1972).
In situ planktonic larvae abundance decreased progressively according to the evolution of the
bloom, with losses approaching 80 % with respect to pre-bloom situation. However, in
incubations experiments no evident larval mortality was observed after 48 hours. All the
studied larvae fed on H. akasiwo, but only B.crenatus nauplii and S. purpuratus echinopluteus
grazed on P.gracile. The possible negative effects of H.akasiwo on planktonic larvae are
discussed.
FEEDING IN LARVAE OF THE INVASIVE GASTROPOD CREPIDULA
FORNICATA (L) DURING NON-BLOOM PERIODS: POTENTIAL USE OF
PICOPHYTOPLANKTON
Thierry Comtet, Frédérique Edmond, François Rigal and Frédérique Viard
Lab. Adaptation & Diversité en Milieu Marin (UMR 7144 CNRS UPMC), Station Biologique de Roscoff, place
Georges Teissier BP74, 29682 ROSCOFF cedex, France; email of presenting author: comtet@sb-roscoff.fr
The larva is a key stage in the life cycle of most marine benthic invertebrates, and is even
more important for invasive species as it is their major vector of dispersal and spread. To
better understand the population dynamics of the gastropod Crepidula fornicata, invasive in
Europe, we studied the seasonal variations in larval abundances in the bay of Morlaix during
three years. Crepidula fornicata larvae occurred at low abundances over a long period (6
months) from February to October. In particular, in 2007, the highest abundance was recorded
in May, well before the chlorophyll a maximum in the bay. We thus investigated which food
sources may be used by the larvae during non-bloom periods. To achieve this aim, we
followed the growth of Crepidula fornicata larvae fed with the Prasinophyceae Micromonas
pusilla (∼2 µm in size) which dominates the picophytoplankton during non-bloom periods in
the English Channel. Low growth rates were observed for larvae fed with M. pusilla at
various concentrations, compared to those fed with the Prymnesiophyceae Isochrysis galbana
(used as a control). To check for the larval ability to ingest picophytoplankton cells, we used
fluorescent beads of various sizes (0,5 to 10 µm). The results showed that larvae of both 1 and
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8th Larval Biology Symposium
Larval feeding strategies
Poster
17 days old are able to ingest beads with a size typical of picophytoplancton. Several
hypotheses might thus be proposed to explain these contradictory observations, such as a
weak assimilation of M. pusilla by the larvae or a low nutritional value.
STOCKING DENSITY OF EARLY LYSMATA AMBOINENSIS LARVAE: HOW
MANY IS TOO MANY?
N. Simões and M. Mascaro
UMDI-Sisal, Facultad
ns@fciencias.unam.mx
de
Ciencias,
UNAM
Yucatán,
México;
email
of
presenting
author:
The effect of initial stocking density on the survival of the first three larval stages of the
cleaner shrimp Lysmata amboinensis using static water replacement was evaluated with three
experiments using Zoea1, Zoea2 y Zoea3, respectively. Three assays (replicates in time) were
run per experiment using larvae from different clutches. Five density treatments (3 - 60 larvae
L-1) with three 1L flask replicates per treatment were used per experiment and respective
assays. Experiments were run in 1L spherical flasks filled with 1 µm filtered seawater kept at
28oC with constant aeration. Larvae were fed daily with a mixture of microalgae, Artemia
nauplii and rotifers. Each assay lasted 3 days (72 h). At the end of each period of 24 h, water
was totally renewed and larvae were counted and classified as “alive”, “moribund” and
“dead”. Larvae classified as “alive” and “moribund” were restocked in a new flask with new
water for another 24 h. Results indicate an inverse relation between survival and stocking
density, with higher mortalities occurring at higher densities. Densities higher than 10 larvae
L-1 at the end of three days showed survival values identical to the treatments of 3 - 10 larvae
L-1. Present results are partially explained by the occurrence of cannibalism and stress. The
recommended stocking density for the first larval stages of L. amboinensis using static water
replacement is 3 – 10 larvae L-1.
8th Larval Biology Symposium
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Eggs, embryogenesis and early larval life
Plenary
THE BILATERALLY ASYMMETRICAL ECHINOPLUTEUS OF STOMOPNEUSTES
VARIOLARIS (LAMARCK)
Richard B. Emlet
Oregon Institute of Marine Biology, University of Oregon, P.O. Box 5389 Charleston, OR 97420 USA; email:
remlet@uoregon.edu
The Indopacific, stirodontid sea urchin Stomopneustes variolaris was raised through
metamorphosis (at 28-30 degrees C) and its larval form was documented. Eggs are ca. 65 um
in diameter and larvae begin to feed within 24 hours of fertilization. As four armed larvae,
they develop postoral arms of which the right is slightly shorter than the left which is also
more heavily pigmented. The larvae eventually develop 12 pairs of arms including a pair of
posterolateral arms of which the right is very long and heavily pigmented and the left is very
short. The asymmetry was found to influence the swimming orientation of the larvae. Except
of the asymmetry, larvae resembled echinoplutuei of Arbacia spp. another stirodontid. Larvae
had 5 to 7 pedicellariae when they metamorphosed after 28 days. The larval asymmetry is
linked to rudiment formation, as one larva that developed a rudiment on the right had side had
reversed arm asymmetry and one larva that did not develop a rudiment approached bilateral
symmetry.
8th Larval Biology Symposium
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Eggs, embryogenesis and early larval life
Oral
FIRST REPORT OF POECILOGONY IN A TROPICAL,
FLATWORM (POLYCLADIDA: COTYLEA: Pericelis cata)
FREE-LIVING
D. Marcela Bolaños and Marian K. Litvaitis
Department of Zoology, University of New Hampshire, Durham, NH 03824, USA; email of presenting author:
dbolanos@cisunix.unh.edu
The embryonic and postembryonic development of the cotylean flatworm Pericelis cata is
described. Multiple eggs per eggshell developed in about 29 days, and early spiral cleavage
was observed. However, subsequent divisions and gastrulation were obscured by large yolk
droplets. These yolk droplets may represent embryos whose development was arrested at
gastrulation and which serve as nurse eggs for the surviving embryos in the eggshell.
Hatching of egg masses lasted for 3 days, and benthic juveniles that had competed
metamorphosis within the eggshell and pelagic larvae hatched simultaneously from the same
egg masses. This represents the first reported case of poecilogony in flatworms and is of
evolutionary significance with respect to larval evolution in the Polycladida. Potential coinsemination by Pericelis orbicularis, a sympatric species was excluded using 28S rDNA data
that unequivocally link offspring and parents as belonging to the same species. A brief redescription of the two species is included, and the intermediate systematic position of
Pericelidae between Cotylea and Acotylea is discussed.
THE SPAWN AND LARVAL DEVELOPMENT OF NASSARIUS BURCHARDI AND
N. JONASII (MOLLUSCA: GASTROPODA: NASSARIIDAE)
Larissa Borysko and Pauline M. Ross
College of Health and Science, Ecology and Environment Research Group, University of Western Sydney,
Hawkesbury H4, Locked Bag 1797, Penrith South DC, NSW 1797, Australia; email of presenting author:
l.borysko@uws.edu.au
The veliger larvae of a number of Nassarius species have been well documented through
laboratory studies. Descriptive accounts have been made of the escape of veligers from their
egg capsules, the modes of feeding, swimming and movement of veligers, the time from
hatching to metamorphosis and the selection of substratum by veligers at settlement.
Additionally, veliger size, growth and morphology, as well as protoconch size and
ornamentation have been documented and in many cases form a basis for identification.
While much is known about Nassarius species from North America and Europe, relatively
little is known about species in Australian waters. Two common Nassarius species along the
Eastern Coast of Australia are N. burchardi and N. jonasii. General anatomy, shell
characteristics and geographic range are known for both species, but spawning, egg capsules
and larval development remain undescribed. The aim of this study was to describe the egg
capsules and larval development of N. burchardi and N. jonasii from hatching to
metamorphosis. Adult N. burchardi and N. jonasii maintained in the laboratory at 20°C in
filtered seawater (35 ppt) deposited egg capsules throughout the year. N. burchardi deposited
between 1- 6 egg capsules, and N. jonasii between 1- 12 egg capsules at a time. The capsules
8th Larval Biology Symposium
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Eggs, embryogenesis and early larval life
Oral
of N. burchardi contained 4-22 eggs while N. jonasii capsules contained 17-38 eggs.
Intracapsular development of both species was 6-8 days under laboratory conditions. At
hatching, the veliger larvae of both N. jonasii and N. burchardi measure 210 ± 10 µm in
length. Planktotrophic development was 4-5 weeks when fed a mixed diet of the algae
Dunaliella tertiolecta and Rhodomonas spp. Several variables including intracapsular
development, success of hatching, number of viable eggs per capsule and veliger abnormality
may be useful to quantify the impact of a range of environmental factors, including endocrine
disruptors.
EGG QUALITY VARIATIONS IN ANCHOVETA ENGRAULIS RINGENS: A
MATERNAL EFFECT TO CHANGING ENVIRONMENTAL CONDITIONS IN
CONTRASTING SPAWNING HABITATS
Leonardo R Castro1, Gabriel Claramunt2, María C Krautz1, Alejandra Llanos-Rivera1
and Paola Moreno2
1
Laboratorio de Oceanografía Pesquera y Ecología Larval. Departamento de Oceanografía y Centro FONDAPCOPAS. Universidad de Concepción. PO Box 160-C. Concepción, Chile; email of presenting author:
lecastro@udec.cl
2
Departamento de Ciencias del Mar. Universidad Arturo Prat. Casilla 121. Iquique, Chile
Engraulis ringens distribution (4-42o S) covers a wide latitudinal range where environmental
conditions vary markedly. In higher latitudes, mean temperature during the spawning season
is lower than in lower latitudes, food is less abundant due to the absence of coastal upwelling
in winter, and wind induced turbulence is higher due to the presence of strong storms. Here
we report differences in egg quality between populations of low (Iquique, 20o S) and high
latitude (Talcahuano, 36o S) off Chile that are part of the coping mechanisms used by this
anchoveta to face different spawning habitats. Eggs differed in size and biochemically
between populations; eggs were larger, total lipids and triacylglycerol contents were much
higher off Talcahuano. The biochemical composition in egg also changed throughout the
spawning season in both populations, with higher lipid contents early in winter (July-August).
Preliminary results show differences in fatty acid egg content between populations and also
along the spawning season. Hatching success decreased along the spawning season and
correlated positively with egg size and lipid contents. Batch fecundity (eggs per batch per
female) and relative fecundity (eggs per female weight) were lower off Talcahuano (high
latitude) during peak winter spawning months. Thus, larger eggs and with higher lipid
contents spawned in the southern population seem to be produced at a cost of a reduction in
fecundity. These set of characteristics seem to be a combined mechanism to facilitate survival
of young offspring in the more adverse winter conditions at higher latitude. These egg
characteristics are determined during oogenesis, representing a maternal effect on the early
life history traits of anchoveta that also might facilitate rapid changes a the population level
through changes in early stages survival in some years, a characteristic of many anchovy
populations.
8th Larval Biology Symposium
Lisbon, 2008
Eggs, embryogenesis and early larval life
Oral
IS THERE ANY EFFECT OF THE HIDROSTATIC PRESSURE IN THE OTOLITH
FORMATION OF TILAPIA LARVAE?
A. T. Correia1,2, A. Oliveira1 and A. Coimbra1
1
Centro Interdisciplinar de Investigação Marinha e Ambiental (CIMAR/CIIMAR), Porto, Portugal; email of
presenting author: atcorreia@ciimar.up.pt
2
Centro Interdisciplinar de Alterações Globais e Bioengenharia da Universidade Fernando Pessoa (CIAGEBUFP), Porto, Portugal.
To check the potential effect of the water column pressure on the otolith growth of fishes, the
off-spring larvae of one couple of Nile tilapia (Oreochromis niloticus) was tested during about
three week after the yolk sac absorption using a pressurizing system. About 120 larvae were
kept in a hyperbaric chamber under a controlled photoperiod (12L/12D), constant water
salinity and temperature and with the same commercial feeding regime. During this short
period the larvae have been exposed to three different hydrostatic pressure regimes: a) to a
normal atmospheric pressure (1 atm); b) to a constant 40 water meters pressure (5 atm); and to
a cyclic vertical migration (1 to 5 atm). After the trial period, the larvae have been measured,
weighed and the sagittal otoliths have been extracted. No significant body differences have
been detected between the three different experiments. Growth increments and otolith
morphometry were evaluated under a light microscope. The effect of the hydrostatic pressure
in the microincrements deposition rates, increments width and otolith growth is discussed
based in the current knowledge about the effect of some abiotic factors in the otolith fish
growth. Until now, the only studies available about this subject used fishes as a model to
study the g-force effect in humans. This is the first attempt to report the potential effect of the
hydrostatic pressure in the increment rhythm and growth of fish otoliths.
METAMORPHOSIS IN SPONGES: A REVIEW
A. Ereskovsky
Centre d’Océanologie de Marseille, Station marine d’Endoume, Aix-Marseille Université - CNRS UMR 6540DIMAR, rue de la Batterie des Lions, 13007 Marseille, France; email: aereskovsky@hotmail.com
Eight main types of larvae have been described in sponges. All larvae are characterized by an
anterior-posterior polarity, by the presence and/or organization of the internal cell mass and
the distribution of spicules (if present). Metamorphosis is the short-term stage of
postembryonic development during which the larva develops into a juvenile. The main feature
of the metamorphosis of sponge larvae is the acquisition of the poriferan Bauplan, which is
mainly defined by the aquiferous system. The first adult structures to be formed de novo are
the exopinacoderm and the basopinacoderm which isolate the young sponge from the external
environment and attach it to the substratum. Later occur the organization of the elements of
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Eggs, embryogenesis and early larval life
Oral
aquiferous system, and the development of the skeleton and the mesohyl. The larval anterioposterior axis becomes the baso-apical axis of the adult regardless of the larval type. During
metamorphosis sponges have two principal types of morphogenesis, which are linked to the
organization of the larva. The first type is characteristic of parenchymella of Demospongiae,
which the distinctive features are the presence of diverse cell types in the internal cavity. A
common feature of the metamorphosis of parenchymellae is the degeneration of the covering
larval epithelium, and the formation of surface layers of the juvenile by internal cells, mainly
archaeocytes. The main role is played by the inner larval cells during metamorphosis. The
second type is characteristic of hollow larvae: amphiblastulae (Calcaronea), coeloblastulae
(Calcinea and some Demospongiae), cinctoblastulae (Homoscleromorpha). A common
feature of these larvae is the differentiation of only external cells during their embryogenesis.
These cells play the main role in metamorphosis. External larval cells form the surface layers
of the juvenile as well as all its internal structures.
OCEAN ACIDIFICATION AND ITS IMPACTS ON BIOMINERALIZATION GENE
EXPRESSION AND SPICULE FORMATION IN STRONGYLOCENTROTUS
PURPURATUS SEA URCHIN EMBRYOS
LaTisha M. Hammond and Gretchen E. Hofmann
Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara,
CA 93106-9610; email of presenting author: hammond@lifesci.ucsb.edu
While marine invertebrate larvae are exposed to a number of abiotic factors and potential
stresses in the pelagic environment (e.g. temperature, salinity, oxygen, food availability, etc.),
one factor of increasing importance is CO2 stress. Carbon dioxide sequestration into the ocean
plays an important role in calcium carbonate (CaCO3) uptake by marine calcifiers. One group
of marine calcifiers are sea urchins, whose larvae take up CaCO3 to form spicules through the
process of biomineralization. The seemingly beneficial increase in oceanic CO2 is in fact
unfavorable for these larvae as the carbonate chemistry results in a decrease in CaCO3 uptake.
While this has the potential to affect the larval skeleton throughout development, a critical
time in the biomineralization process occurs when the spicule first begins to form.
Investigating how key biomineralization genes are regulated during this time in early
embryonic and larval development will help elucidate how larval spicules are affected by
increases in CO2. For this experiment S. purpuratus urchins were spawned and the embryos
were reared in filtered seawater at 3 different CO2 concentrations: 380 ppm (the current
oceanic CO2 concentration), 550 ppm, and 990 ppm (two potential future scenarios predicted
by the IPCC). Embryos were sampled across 5 different developmental points between
blastula and early prism stage, all of which occur early in the biomineralization process.
Samples were extracted for total RNA and subsequent transcript analysis via quantitative PCR
to determine the expression patterns of the following biomineralization genes: SM30-b, SM50,
msp130-1, and carbonic anhydrase. The results of this study will help elucidate how the S.
purpuratus biomineralization process will be affected by CO2 in early development and, more
broadly, how such larvae are likely to respond to future increases in ocean acidification.
8th Larval Biology Symposium
Lisbon, 2008
Eggs, embryogenesis and early larval life
Oral
PHYSIOLOGICAL AND MORPHOLOGICAL PLASTICITY OF CALANOID
COPEPOD EGGS
Benni W. Hansen, Guillaume Drillet, Jonas K. Højgaard, Per M. Jepsen, Mie H. Sichlau
and Kristian Sjoegren
Roskilde University, Department of Environmental, Social and Spatial Change, DK-4000 Roskilde, Denmark;
email of presenting author: bhansen@ruc.dk
Subitaneous eggs from a near shore calanoid copepod (Acartia tonsa Dana) hatch within days
in Danish waters at norm-situations. We demonstrate the physiological plasticity of the egg
stage of relevance for the adaptation to the fluctuating estuarine environment. A large fraction
of the subitaneous eggs remain viable at a broad range of temperatures and salinities. Eggs
even tolerate hypoxia, anoxia and sulphide. The eggs exhibit an improved hatching rate and
final -success from acclimated copepods vs. non-acclimated copepods within temperatures
from 1.5-24 ºC. The eggs had a significant tolerance to salinities from 30 and even down to 0,
and act as perfect osmometers where water is transported freely across the egg membrane. No
significant elevated respiration is detected when eggs are challenged by abrupt salinity
changes. However, when exposed for extreme challenges they respond by entering quiescence
with arrested development of the embryo. During that condition, egg metabolism is shutdown by an order of magnitude, the embryo deplete certain biochemical constituents, and
thereby secure that a significant fraction of the eggs survives at least a year. Approximately
50 species of marine calanoid copepods including our target species are described to include
true diapause eggs in their life cycle. Those eggs are designed for long time storage, and they
need a several months long refractory phase before they are able to hatch. Diapause eggs can
be present in relatively deep sediments. The pattern of diapause egg distribution in Danish
waters were clearly determined by the sediment characteristics, and we report diapause eggs
of an age of ~70 years still viable. The morphological differences by the three egg types
produced by the same species of copepod are not trivial. We demonstrate a surprising
plasticity in surface morphology of eggs within clutch spawned by individual females and
discuss the relevance of ootaxonomy.
FIRST DESCRIPTION OF EMBRYO DEVELOPMENT AND THE FREESWIMMING
LARVA
OF
VERONGID
DEMOSPONGES
(PORIFERA:
DEMOSPONGIAE): EVIDENCE FOR PARALLEL EVOLUTION WITHIN
PORIFERA.
M. Maldonado
Department of Aquatic Ecology, Centro de Estudios Avanzados de Blanes (CSIC), Acceso Cala St. Francesc 14,
Blanes 17300, Girona, Spain; email: maldonado@ceab.csic.es
The sponges (Porifera) make a phylum traditionally split into 3 classes: Calcarea,
Hexactinellida, and Demospongiae. The demosponges represent about 85% living sponges
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and contains around 15 taxonomic orders, distributed into two larges subclasses
Tetractinomorpha and Ceractinomorpha. Members of most demosponge orders possess an
internal inorganic skeleton of siliceous spicules. Nevertheless, there are 3 orders in the
subclass Ceractinomorpha (i.e., Verongida, Dictyoceratida, and Dendroceratida) in which this
mineral skeleton has completely been replaced for a proteinaceous skeleton made of spongin
fibers. These three orders are jointly referred to as either “keratose” or “horny” sponges, being
very well represented in tropical reefs and other shallow-water warm habitats. While
Dictyoceratida and Dendroceratida are viviparous sponges that brood their embryos and
release a tufted parenchymella larva, the Verongida are thought to shed their gametes into the
water column. For this reason, the verongids have completely eluded any embryological
research so far, despite several attempts. By investigating the sponge Aplysina aerophoba, I
have documented for the first time fertilization, embryo development, transference of
endosymbiotic microbes, and the free-swimming larval stage of Verongida. The
ultrastructural features of embryos and larvae indicate that the verongids should not be
included into to the subclass Ceractinomorpha, being more related to sponge orders lacking
spongin fibers than to those bearing skeletons of spongin fibers. Therefore, these new
embryological information suggest that the skeletons of spongin fibers have independently
emerged at least twice within Porifera to replace skeletons of siliceous spicules, providing an
amazing example of within-phylum convergent evolution. The phylogenetic signal provided
by these embryological features is also briefly discussed in the frame of recent molecular
analyses of the internal relationships within phylum Porifera.
OXYGEN AND EMBRYOS IN INVERTEBRATE EGG MASSES: MODELS,
MANIPULATIONS, AND IN SITU MEASUREMENTS
A. L. Moran1 and H. A. Woods2
1
Department of Biological Sciences, Clemson University, Clemson, SC; email of presenting author:
moran@clemson.edu
2
Department of Biological Sciences, University of Montana, Missoula, MT
Embryos of many aquatic and marine organisms develop in gelatinous egg masses, and
physiological models of oxygen demand (by embryos within masses) and oxygen supply (by
diffusion) have demonstrated that oxygen can be highly limiting to development and survival
of embryos. We demonstrated in the laboratory that embryos in egg masses are often oxygenlimited, and that both structural factors such as egg mass thickness and density of embryos
and environmental factors such as water flow and temperature affect the degree of O2
limitation. While these patterns are clear from laboratory work, in their natural environment
egg masses experience a wide range of conditions that are very likely to affect O2 gradients:
boundary layers, temperature fluctuations, secondary egg mass structure, and production or
consumption of oxygen by nearby organisms are all likely to change the availability of
oxygen and, hence, affect internal oxygen gradients. We used an underwater picoammeter
equipped with a 50-µm oxygen probe to take in situ measurements of oxygen gradients in
both artificial and natural invertebrate egg masses in the field. In a cold-temperate ecosystem,
internal oxygen levels were as low as 20% of ambient; in addition, internal field O2 was
comparable to zero-boundary-layer conditions in the laboratory, suggesting that under high-
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flow field conditions the zero-boundary-layer condition assumed by most models is likely
adequate. In the extreme cold nearshore Antarctic environment oxygen levels were high under
all conditions, suggesting that the constant extreme cold and high O2 in the Southern Ocean
leads to high oxygenation of masses relative to temperate systems.
LARVAL DEVELOPMENT AND CRUSTACEAN EVOLUTION: CASE-STUDIES
ON SMALLER CRUSTACEAN TAXA
Jørgen Olesen
Natural History Museum of Denmark, Universitetsparken 15, DK-2100 Copenhagen, Denmark; email:
jolesen@snm.ku.dk
Crustacea show an enormous diversity of developmental patterns. Some develop gradually
over many stages while others change morphology abruptly from one stage to another. Many
taxa have unique larval types (with special names) and direct development have evolved
independently a number of times. Non-malacostracans (Entomostraca) holds the key for
elucidating early crustacean evolution, and in this light the development of a number of taxa
have been examined (or re-examined), such as Remipedia, Cephalocarida, Branchiopoda,
Branchiura, and Mystacocarida. The outcome of this work is complex, but have (1) provided a
largely and hitherto largely unstudied dataset for phylogenetic analyses, and (2) given quality
data for considerations of heterochronic evolution of various crustacean taxa. Examples from
own work that will be mentioned in talk: (1) Larvae of Branchiopoda have a characteristic
morphology that support the monophyly of this group. (2) Studies of branchiopod limb
development have showed that segmented legs have evolved secondarily from phyllopodous
limbs within Branchiopoda. (3) Study of larval development and phylogeny of Branchiura
(fish lice) shows that the parasitic, maxillulary suction discs probably have evolved within
Branchiura and is not ancestral for the group. (4) Newly discovered larvae of Remipedia have
three pairs of (naupliar) appendages which supports their crown-group crustacean position,
possibly close to the Malacostraca.
STEPWISE
EVOLUTION
OF
MATERNAL
INVESTMENT
ECHINODERMATA: LINKING EGG AND JUVENILE QUALITY
IN
THE
Thomas A. A. Prowse1, Mary A. Sewell2 and M. Byrne3
1
Bosch Institute, University of Sydney, NSW 2006, Australia; email of presenting author:
tprowse@anatomy.usyd.edu.au
2
School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
3
Bosch Institute, University of Sydney, NSW 2006, Australia
In marine invertebrates, feeding (planktotrophic) and nonfeeding (lecithotrophic) modes of
development represent different approaches to the trade-off between egg size and fecundity.
Within the Echinodermata, species with large eggs and lecithotrophic larvae have
independently evolved from species with small eggs and planktotrophic larvae a number of
times. Facultatively planktotrophic larvae (larvae that can feed but do not need to feed to
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metamorphose successfully) represent a necessary, intermediate mode of development that is
probably evolutionarily unstable. The transition to lecithotrophic development in echinoderms
has involved a disproportionate increase in egg lipid provisioning. We have therefore
quantified lipid classes present in the eggs of multiple species from four echinoderm classes
(asteroids, ophiuroids, echinoids and holothuroids) and also documented lipid reserve
depletion during larval development. The eggs of lecithotrophic echinoderms are not merely
scaled up versions of planktotrophic eggs, rather oogenic processes have been modified to
favour deposition of energetic lipids. Furthermore, eggs of planktotrophic species are
dominated by triglycerides whereas those of lecithotrophs primarily contain glycerol ethers, a
related lipid class believed to be more suitable for long-term energy storage. This case of
convergent evolution may reflect selection to provision juveniles for the vulnerable postmetamorphic phases. Larval rearing experiments support this hypothesis: whereas egg
triglycerides are rapidly depleted by feeding larvae, eggs of lecithotrophs contain far more
energetic lipid than that required to produce a juvenile. When combined with data from
previous data for echinoderms, the scaling of egg lipid content with egg volume can be
robustly examined. A sigmoid function best describes this relationship and suggests a steplike increase in egg lipid provisioning at egg sizes around those required for facultative
planktotrophy. Once a facultatively planktotrophic species has evolved, the direct link formed
between egg and juvenile quality may have resulted in strong selection favouring increased
maternal investment of energetic lipid.
APPLICATION OF DNA BARCODING TO UNDERSTANDING THE EARLY LIFEHISTORY OF MARINE INVERTEBRATES.
Mary A. Sewell1 and Shane D. Lavery1,2
1
School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand;
email of presenting author: m.sewell@auckland.ac.nz
2
Leigh Marine Biology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
DNA barcoding has been recently proposed as a solution to many taxonomic problems, such
as species identification, species discovery, and biodiversity assessment. However, it was
recognized over 15 years ago by a larval ecologist (Olsen et al. 1991) that a short DNA
sequence would be extremely usedful for the taxonomic identification of morphologically
cryptic marine larvae. Although there are currently some limitations to DNA barcoding larval
organisms (e.g., inconsistent amplification of COI sequence, poor comparative databases for
adult sequences), several studies have shown that molecular taxonomy in general can be a
powerful tool to the larval ecologist. Here we describe, using examples from our research on
Antarctic meroplankton, four case studies where DNA sequencing of 16s rRNA and COI has
revealed important information about the early life-history of marine organisms: (1)
identification of the source of eggs from a mass-spawning at Cape Hallett, in the northern
Ross Sea, (2) determination of an extended spawning season in the asteroid Odontaster
validus, (3) identification of developmental stages of the same species, and (4) the future
application of this research to addressing paradigms in larval ecology such as Thorson’s Rule.
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GROWING HALF OF THE BODY: DEVELOPMENT OF THE NERVOUS SYSTEM
DURING REGENERATION IN STARFISH LARVAE
Nadia Suárez-Bosche1, Débora Iglesias-Rodríguez1, Mario Suárez-Arriaga2 and
Fernando Sánchez-Herrejon2
1
National Oceanography Centre, University of Southampton, European Way, Southampton, SO14 3ZH, UK;
email of presenting author: nesubo@soton.ac.uk
2
Faculty of Sciences, Michoacan University - UMSNH, Morelia, Mich., México.
The understanding of developmental mechanisms at the molecular level is a crucial part of
modern embryology. In recent years, considerable research effort has been focused on
identifying novel genes that control developmental processes. Regeneration is the reactivation
of developmental processes during postembryonic life to restore damaged or missing tissues.
Despite the ecological, physiological and evolutionary importance of regeneration, direct
morphological observations and detailed studies on the development of the nervous system in
echinoderm larvae have been overlooked. We present the first description of the mechanisms
involved in development and organization of the larval nervous system during regeneration.
Our results using confocal microscopy reveal novel mechanisms of regeneration using the
antibodies 1E11 and serotonin that appear to be neuro-specific in two Pacific starfish larval,
Pisaster ochraceus and Orthasterias Koehleri.
EGGS, ZYGOTES AND LARVAE IN OVIPAROUS SPONGES
M. J. Uriz, M. P. Piscitelli and S. Mariani.
Centre d’Estudis Avançats de Blanes. CEAB.CSIC. Accés Cala St Francesc, 14. 17300 BLANES (Gitona)
Spain; email of presenting author: iosune@ceab.csic.es
Sponges are traditionally divided into viviparous and oviparous. Most studies on sponge
reproductive features have focused on viviparous sponges because a complete picture of the
whole process can be captured by periodically sampling some individuals along the year.
Conversely, the information is strikingly confusing for the oviparous sponges. Here, we
report on some reproductive features of the oviparous sponge Cliona viridis, which remained
either unknown or poorly known (i.e. cycle of gamete formation, zygote release and larval
hatching, and zygote, “eggshell” and larva ultrastructure). The new information obtained,
together with a review of the available literature, allowed us to enumerate distinctive traits
for oviparous sponges with internal fertilisation and oviparous sponges with external
fertilisation. The former are simultaneous hermaphrodites, while those with external
fertilisation seem to be gonochoric or successive hermaphrodites, and present simultaneous
spawning at a population level. The target sponge is simultaneous hermaphrodite. Ooctytes
were produced almost all the year round. In contrast, spermatogonia were formed only during
one week, once oocytes were mature. Fertilisation occurred in May. The sponge released
early zygotes, which is in agreement with the internal fertilisation previously reported. An
“eggshell” consisting in two fibrous layers contained the embryo during development.
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Uniformly ciliated larvae hatched the “eggshell” through an upper orifice. The larval
ultrastructure does not allow differentiating the Cliona larva from other typical
parenchymella. Embryo development to the larval stage was notably faster in this species
than in viviparous sponges, in agreement with the general trend of oviparism vs. viviparism.
Our results indicate that apparent contradictions in the literature on some reproduction traits
of oviparous sponges may be due to their consideration as a uniform entity. Oviparous
species that release zygotes appear to be concentrated in the Order Hadromerida, while
oviparism with external fertilisation has been reported in several others of Demospongiae
(i.e. Spirophorida, Chondrosida, Petrosida and Verongida).
LARVAL AND JUVENILE DEVELOPMENT OF THE SEA BISCUIT CLYPEASTER
SUBDEPRESSUS (ECHINODERMATA: CLYPEASTEROIDA)
Bruno C. Vellutini and Alvaro E. Migotto
Centro de Biologia Marinha da Universidade de São Paulo, Av. Manoel H. do Rego km131,5, CEP:11600-000
São Sebastião, SP, Brasil; email of presenting author: organelas@gmail.com
Sea biscuits and sand dollars have unique morphology among irregular echinoids. Their
evolution is associated with occupation of sand beds and retention of juvenile characters. To
investigate the developmental basis for the origins of Clypeasteroida, the development of
Clypeaster subdepressus was described. After sperm entry, male pro-nucleus migrated and
fused with female pro-nucleus in ~12min (0.1µm/s). First cleavage occurred after 80min; 32
cell stage reached 3h post fertilization (h.p.f.). Blastula hatched 7.5h.p.f.; ingression of
mesenchyme cells into blastocoel initiated 10h.p.f.; archenteron extension began 14h.p.f. and
lasted 6h. Two coelomic sacs evaginated from the archenteron before 48h.p.f.; feeding began
on day 3. Hidropore and vestibule opened around day 5; vestibule fuses with left coelom on
day 12 originating a rudiment oriented 45° to larval A/P axis. Arms of competent larvae (20
days) moved 90° posteriorly exposing the vestibule, and allowing one foot to touch
substratum. Metamorphosis initiated with substratum adhesion and complete exposure of
rudiment. Tissue regression took ~1h30min. Juvenile had 5 spines, 5 sphaeridia and 10
ambulacral feet on oral surface; each pair of feet displayed a tapering sensorial podia and a
locomotory podia with ring-shaped spicule; aboral surface had 10 spines and 5 locomotory
feet. Elements of the Aristotle's lantern were organized in 5 groups with 5 ossicles each. In 2
days hemipyramids, teeth, and gut were formed; anus opened on aboral surface.
Differentiation of digestive tube and complete development of pyramids occurred in 7 days,
when peristomial membrane became functional and mouth opened. Crown-tipped spines and
plates occupied the aboral surface, but tri-dentiated pedicellariae appeared later, only on
posterior region. Juveniles apparently grazed on algal and bacteria films scraped from sand
grains added to culture dishes. Their growth was slow; they measured ~250 µm in diameter
after metamorphosis, reaching ~600 µm 8 months later. Sphaeridia were not internalized
during this period.
EXAMINING THE IMPACTS OF CLIMATE CHANGE ON MARINE ORGANISMS:
EFFECTS OF OCEAN ACIDIFICATION ON LARVAL MARINE SNAILS
8th Larval Biology Symposium
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Eggs, embryogenesis and early larval life
Oral
Mackenzie L. Zippay and Gretchen E. Hofmann
University of California, Santa Barbara: Department of Ecology, Evolution and Marine Biology, Santa Barbara,
CA 93106; email of presenting author: zippay@lifesci.ucsb.edu
Currently, 33% of the carbon dioxide given off from burning fossil fuels enters the ocean,
reducing its alkaline pH. Estimates suggest that a drop in pH to 7.9 from 8.05 could decrease
calcification rates of many marine organisms up to 60% by the end of the century. As a
consequence of the predicted elevated levels of greenhouse gases, it is important to
understand the underlying mechanisms between increase carbon dioxide and calcification in
marine organisms. This information may provide us with how organisms might be able to
adapt or alter their physiological responses to climate change and identify species that may be
particularly vulnerable under such conditions. This research centers on determining the effects
of increased levels of dissolved carbon dioxide on shell formation in larvae of red abalone
(Haliotis rufescens). We are measuring the effects of ocean acidification on shell formation
by rearing larvae in tanks with three different concentrations of carbon dioxide identified by
the IPCC. These levels span the range of current carbon dioxide levels (385ppm) to a “worst
case” (1020ppm) scenario for the year 2100. Measurements will be done at two stages in
development (trochophore and veligers) to determine shell thickness and hardness. In addition
to morphological measurements, a sub-set of larvae will be taken from each carbon dioxide
treatment and analyzed for gene expression using quantitative PCR. By understanding the
regulatory pattern of the genes responsible for shell formation in abalone, we may gain insight
in how abalone may respond to the changing oceans. Most importantly, this research may
give us insight into how these early life history stages may help us in answering how our
marine ecosystem will change in response to the oceans becoming more acidic.
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Eggs, embryogenesis and early larval life
Poster
A HARPACTICOID COPEPOD WITH AN UNUSUAL NAUPLIAR MOUTH AND
MANDIBLE
Viatcheslav N. Ivanenko1, Frank D. Ferrari2 and Hans-Uwe Dahms3
1
Department of Invertebrate Zoology, Biology Faculty, Moscow State University, Moscow 119 899, Russia;
email of presenting author: Ivanenko.slava@gmail.com
2
IZ/MSC; MRC-534, National Museum of Natural History, Smithsonian Institution, 4210 Silver Hill Rd.,
Suitland, MD 20746 U.S.A.
3
National Taiwan Ocean University, Institute of Marine Biology, 2 Pei-Ning Road, KEELUNG, Taiwan, 202
Six naupliar stages were found in large numbers along with all six copepodid stages of
Tegastes falcatus (Norman, 1869) (Crustacea, Copepoda, Tegastidae) apparently feed on
suctorian ciliates growing on colonies of the bryozoan Flustra foliacea (Linnaeus, 1758) in
the White Sea. The labrum is expressed as a simple fold which does not cover the mouth. The
antennal endopod is a subchela against the basis at NII; its distal endopodal segment becomes
bifurcate at NIII. A chela on the naupliar mandible consists of the endopod opposite a
distoventral attenuation of the basis on NII-NVI. The segmental elements of a chela are
present at NI, although the endopod does not oppose the basis at this stage. The maxillule is a
unilobe bud with one seta at NIII that gains a second seta at NV and is transformed into a
simple bilobe bud with three setae at NVI. The maxilla and maxilliped are each an asetose,
ventral attenuation at NVI.
EFFECTS OF LIGHT INTENSITY AND PHOTOPERIOD ON THE GROWTH AND
SURVIVAL RATES OF CULTURED SCOPHTHALMUS RHOMBUS L. LARVAE.
Lorenzo Márquez, Marcelino Herrera, Ana Rodiles and Ismael Hachero-Cruzado.
IFAPA Centro "Agua del Pino", Carretera Cartaya-Punta Umbría s/n, Apdo.: 104. Huelva, Spain; email of
presenting author: lorenzo.marquez.ext@juntadeandalucia.es
Only a few papers have previously been devoted to the larval biology of the brill,
Scophthalmus rhombus L., although it is an interesting species for both basic and applied
research. Therefore, a factorial experiment was designed in order to investigate the effects of
light intensity and photoperiod on the growth and survival rate of brill larvae (Scophthalmus
rhombus L.), cultured in seawater during the first month of life. Temperature was kept at
16,0ºC; initial larval density was ca. 35 L-1. Larval fish were fed Isochrysis galbana plus
Nannochloropsis gaditana enriched Brachionus plicatilis rotifers and Selco™ (Inve, Inc)
enriched Artemia sp. metanauplii since day 2 and day 18 respectively. Cultures were
performed in approx. 43.5 L cylindrical-conical tanks. Experimental factor levels were: 300 lx
and 1250 lx for light intensity, and 24:0 and 12:12 (light:darkness) for photoperiod. Each
factor combination of light intensity/photoperiod was replicated 3 times. Larval total lengths
and survival rates were measured on a weekly basis; they were analysed by means of
ANCOVA tests with larval age as cofactor and light intensity and photoperiod as categorical
factors. The main results were: i) the shorter photoperiod promoted higher growth and
8th Larval Biology Symposium
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Eggs, embryogenesis and early larval life
Poster
survival rates than the longer one; ii) light intensity had no effect either on growth or on
survival in the range tested; iii) the minimum total length observed at the beginning of the
metamorphosis was 7.80 mm. The results suggest: i) a minimal light intensity threshold for
pre-metamorphic larvae bellow 300 lux of white light and ii) a trade-off between the daily
period for which prey is visible and another undetermined factor or factors related to
photoperiod, e.g., daily energy expenditure due to swimming activity, leading to an optimal
photoperiod shorter than 24:0 (light:darkness). This work has been founded by the project
PROMAR SP5.P117/03 (Interreg IIIA España-Portugal).
EARLY LARVAL LIFE
IN THE AEOLIDACEAN BERGHIA COLUMBINA
MOLLUSCA: OPISTHOBRANCHIA) IN THE ATLANTIC COAST FROM
SOUTHWESTERN SPAIN
I. Martínez-Pita1 and F. J. García2
1
I.F.A.P.A. Centro “Agua del Pino”. Carretera El Rompido-Punta Umbría, km. 3.8. C. P.: 21459. El Rompido.
Huelva. Spain; email of presenting author: ines.martinez.ext@juntadeandalucia.es
2
Area de Zoología, Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide.
Carretera de Utrera km. 1. C.P.: 41013, Sevilla, Spain.
Adults of Berghia columbina were collected in the intertidal area of El Portil Beach (Huelva,
Southwestern Spain) and its biological cycle was studied during a year in the laboratory. This
species has a embryonic phase which lasts 7.87 days (temperature 18ºC), its development is
planktotrophic and the medium length of the veliger which hatches is 133.92 µm ± 7.55. The
larvae were fed with Isochrisis galbana 104 cells per ml each two days. The metamorphosis
was induced with KCl. The morphological changes were observed and the length measured
each 3 days from hatching to death. Throughout the planktonic phase the larvae doubled the
size (length) and they reached 254 µm in length. The growth rate is faster the first 12 days
than in the last 9 days, in fact the larvae grew 83 µm and 37 µm respectively. The left
digestive gland became green 3 days after hatching and it grew during the first 9 days until
moving the stomach and the right digestive gland to the right. Two eye spots were visible on
the anterior zone of all veliger 9 days after hatching. The foot became longer and thicker
throughout all the larval phase. Its length increased from 51.24 µm ± 5.46 at the beginning to
115.7 µm ± 2.08 18 days after. The propodium began to appear 15 days after hatching and it
became more visible three days after. Two larvae survived 21 days but, although it seemed
that they had achieved the competent phase, none metamorphosed.
EARLY
LARVAL
LIFE
IN
THE
NUDIBRANCH
POLYCERA
AURANTIOMARGINATA (MOLLUSCA: OPISTHOBRANCHIA) IN THE ATLANTIC
COAST FROM SOUTHWESTERN SPAIN
I. Martínez-Pita1 and F. J. García2
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Eggs, embryogenesis and early larval life
Poster
1
I.F.A.P.A. Centro “Agua del Pino”. Carretera El Rompido-Punta Umbría, km. 3.8. C. P.: 21459. El Rompido.
Huelva. Spain; email of presenting author: ines.martinez.ext@juntadeandalucia.es
2
Area de Zoología, Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide.
Carretera de Utrera km. 1. C.P.: 41013, Sevilla, Spain.
The reproduction of the nudibranch Polycera aurantiomarginata has been studied during a
year on the Atlantic coast from Southwestern Spain. This species has a planktotrophic
development so, at the end of the embryonic phase, which lasts 8.4 days (temperature 18ºC); a
plankctotrophic veliger hatches, its medium length is 134.97 µm (Martinez-Pita et al., 2006).
The larvae were fed with Isochrisis galbana 104 cells per ml. The morphological changes
were observed and the length measured each 3 days since hatching to death. The larvae size
(length) increased 50% and the last length, measured 24 days after hatching, was 196 µm,
nevertheless some larvae measured 15 and 18 days since hatching had 210 µm in length. The
shell and the left digestive gland were the first structures with underwent morphological
changes. The shell grew between 10 and 15 % and a rift linked the new part with the old one
is observed. The left digestive gland became bigger and green because of the algae. Nine days
after hatching two eye spots were visible on the anterior zone of some veliger, this character
was present in all larvae three days after. A little, transparent and long bag was observed in
the base of mantle cave 12 days after hatching, this structure bate rhythmically so it could be
the larval heart. The foot changed also throughout the larval development, it grew 33 µm in
length and 12 days after hatching it became thicker. The propodium began to appear between
15 and 18 days after hatching. One larva survived 24 days but none metamorphosed.
THE EFFECT OF SALINITY AND TEMPERATURE ON NAUPLII LARVAE OF
THE ESTUARINE BARNACLE ELMINIUS COVERTUS (FOSTER 1982)
Laura M. Parker, Larissa Borysko and Pauline M Ross
College of Health and Science, Ecology and Environment Research Group, University of Western Sydney,
Hawkesbury H4, Locked Bag 1797, Penrith South DC, NSW 1797, Australia; email of presenting author:
l.borysko@uws.edu.au
Larvae of aquatic invertebrates are highly sensitive to physical changes in their environment,
making these stages critical in determining the final distribution and abundance of settlers,
recruits and adults into a population. Due to their sensitivity, changes in factors such as the
salinity and temperature of aquatic habitats have the potential to impact upon their survival
and development. Although there is a significant body of work on the effect of salinity and
temperature on larval development, these factors have often been investigated independently
of each other. Only recently have the synergistic effect of these factors been considered.
Further, very few studies have considered the effects of pulse episodes of environmental
factors, such as altered salinity on the survival of larvae. The aim of this study was to
determine the effect of pulse episodes of salinity and temperature on the development and size
of nauplii larvae of the Australian estuarine barnacle, Elminius covertus (Foster 1982). The
larvae of E. covertus completed naupliar development between 8 and 16 days over a range of
8th Larval Biology Symposium
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Eggs, embryogenesis and early larval life
Poster
salinities (15-40 ppt) and at two temperatures (14°C and 20°C). The optimal development of
naupliar larvae was found in the salinity range between 30-35 ppt at 20ºC (8-9 days). As the
salinity deviated from the optimal, the time spent in the larval stage increased and the mean
size (total length and shield width) of nauplii decreased. When nauplii were exposed to
suboptimal pulse episodes of salinity, before or after an episode of optimal salinity, the
naupliar size and time spent in the naupliar stage increased. This study found that suboptimal
salinities increases time of naupliar development and alters naupliar size, perhaps depleting
energy stores vital for metamorphosis to the cyprid stage and making nauplii more susceptible
to predation.
THE PUERULUS STAGE OF THE MEXICAN SPINY LOBSTER, PANULIRUS
INFLATUS (DECAPODA: PALINURIDAE)
Raúl Pérez-González
Universidad Autónoma de Sinaloa (Facultad de Ciencias del Mar). Apartado Postal 610, Mazatlán, Sinaloa,
México; email: raulp@ola.icmyl.unam.mx
The spiny lobster Panulirus inflatus is endemic to the Mexican Pacific coast, where it sustains
local traditional fisheries throughout its geographic range, but it remains poorly known. In
this study, the puerulus of P. inflatus is described from specimens collected in the lower part
of the Gulf of California. The body is completely transparent, except for the eyes (yellow in
some specimens, almost black in others) and for red chromatophores at the lateral margins of
cephalothorax, the 2-5 abdominal somites, the antennal peduncles and the proximal antennal
segments, as well as at the distal margins of telson and uropods. Total and carapace lengths
range between 22.1 and 24.9 mm (from the anterior region of the antennular-plate to posterior
margin of telson) and from 7.6 to 9.9 mm (measured from between the two supraorbital
spines to the posterior margin of cephalothorax), respectively. The carapace is elongate and
subcylindrical, with 2 large supraorbital spines separating the prominent eyes. The following
two pairs of spines are smaller than the supraorbital in the submedium rows and are separated
by a gap. There are two pairs of spinules behind these spines. One additional pair of spine is
located close to the lateral margin of the carapace behind the two pairs of spinules.
8th Larval Biology Symposium
Lisbon, 2008
Ontogenetic strategies in extreme aquatic
environments
Plenary
EARLY LIFE HISTORY STRATEGIES OF BENTHIC INVERTEBRATES
INHABITING HYDROTHERMAL VENTS: ADAPTATIONS TO AN EXTREME
ENVIRONMENT?
A. Metaxas
Department of Oceanography, Dalhousie University, Halifax, NS, Canada B3H 4J1; email: metaxas@dal.ca
The hydrothermal vent environment affords some unique challenges to its inhabitants. Vent
organisms of all stages must be able to tolerate high, but also fluctuating, temperatures, H2S
and metal concentrations. Because of the ephemeral nature and patchy distribution of these
habitats, mechanisms that enhance larval dispersal (for colonization of newly opened vents)
and larval retention (for the maintenance of established populations) must operate
simultaneously. A diverse range of biological and chemical cues, also with a patchy
distribution, must be sampled and selected by successful larval settlers. Spatial and temporal
patterns in recruitment can arise in response to chemical (vent fluid composition) and
biological (predation, access to fluid, interference) factors. Given the success as evidenced by
extremely high abundance attained by some vent species (e.g. the limpet Lepetodrilus fucensis
on the Juan de Fuca Ridge), we can conclude that early life-history strategies are in place to
overcome the challenges of this environment. In this talk, I will explore some of these
strategies and compare them to those used by benthic invertebrates in more “benign” habitats.
REPRODUCTION IN THE COLD: COSTS AND CONSEQUENCES OF HIGHLY
SPECIFIC TRAITS
Sven Thatje
National Oceanography Centre, Southampton, United Kingdom; email: svth@noc.soton.ac.uk
Reproduction in cold waters is constrained by some of the harshest environmental conditions
found on Earth. Polar invertebrates are known to show few species with planktotrophic larvae
when compared with overall benthic diversity. This has often been discussed by a failure to
synchronize prolonged developmental times at low temperatures with short seasons of food
availability, generally selecting against feeding larvae and complex early life cycles. From a
global-scale perspective, reproduction in polar seas was explained by macroecological
patterns that basically reflect a shift in energy allocation of maternal origin into fewer but
nutrient richer larvae, often referred to as “evolutionary temperature adaptation” (i.e.
Thorson-Rass rule). Shifts in offspring energy allocation in some taxa were found expressed
by reduced female fecundity, egg or offspring size clines, and the loss of morphological
plasticity in complex larval cycles with increasing latitude, to mention just a few. In this
paper, I review the knowledge of reproductive traits in marine invertebrates thriving in
Antarctica from an evolutionary perspective of cold adaptation. I will critically discuss
whether the advantages and disadvantages of either being a brooder or broadcaster may have
fostered Antarctic diversity and community structure over long geological timescale and in
particular in response to late-Cenozoic climate oscillation.
8th Larval Biology Symposium
Lisbon, 2008
Ontogenetic strategies in extreme aquatic
environments
Oral
VERTICAL MIGRATION OF THE LARVAE OF THE DEEP-SEA MUSSEL
“BATHYMODIOLUS” CHILDRESSI: EMPIRICAL TEST OF AN ENERGETIC
MODEL
Shawn M. Arellano and Craig M. Young
Oregon Institute of Marine Biology, University of Oregon, P.O. Box 5389, Charleston, OR; email of presenting
author: arellano@uoregon.edu
Researchers have hypothesized that the larvae of deep-sea, chemosynthetic bathymodiolin
mussels (Mytilidae) do not migrate to the surface waters, since migration may increase
advection of larvae away from suitable habitats. Egg sizes and larval shells indicate
planktotrophy, but deep-water food sources for these larvae are unknown. Moseley’s (1880)
suggestion that larvae of deep-sea animals may migrate into the euphotic zone to feed was
overshadowed by Thorson’s (1950) assertion that such a migration would be energetically
impossible. Using cultured larvae of “Bathymodiolus” childressi, a cold-seep bathymodiolin
from the Gulf of Mexico, we empirically derive each parameter of a published energetic
model used to estimate the migration potential of larvae originating in the deep sea. In
addition, we compare the model’s prediction of migration potential to direct evidence from
plankton samples. We suggest that larvae of “B.” childressi are energetically capable of
migrating to the surface from 650 m depth without feeding. Larvae are tolerant of the
temperature and salinities present in the upper water column of the Gulf of Mexico, and we
found veligers of “B.” childressi in the plankton up to at least 100 m depth. The large sizes of
these veligers suggest a slow migration to the surface of up to 4 months. We calculated a
metabolic lifespan for larvae of “B.” childressi of up to 74 days, indicating that larvae could
live at depth for extended periods without feeding. Recent genetic analyses do not reveal
differentiation between widespread populations of “B.” childressi in the Gulf of Mexico.
Moreover, a historic connection between these populations and genetically-similar congeners
across the Atlantic has been suggested. Extended larval periods combined with vertical
migration into faster-moving currents in the upper water column may provide a mechanism
for the suggested widespread dispersal of these larvae.
LARVAL
SHELL
MORPHOLOGY:
CHEMOSYMBIOTIC MYTILIDS?
REVEALING
EVOLUTION
OF
Luciana Génio1, 2, Steffen Kiel3, Marina R. Cunha2, John Grahame1 and Crispin T. S.
Little1
1
Earth & Biosphere Institute, University of Leeds, Leeds LS2 9JT, United Kingdom; email of presenting author:
l.genio@see.leeds.ac.uk
2
CESAM – Centro de Estudos do Ambiente e do Mar, Departamento de Biologia, Universidade de Aveiro,
3810-193 Aveiro, Portugal.
3
Institute of Geosciences – Paleontology, Christian-Albrechts-University Kiel, Ludewig-Meyn-Str. 10, 24118
Kiel, Germany.
The colonization of patchy and ephemeral chemosynthetic habitats (hydrothermal vents, cold
seeps, whale- and wood-falls) by sessile organisms would not be possible without a larval
8th Larval Biology Symposium
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Ontogenetic strategies in extreme aquatic
environments
Oral
stage. Mytilids belonging to the genus Bathymodiolus are among the most widespread taxa at
vent and seep sites, and species diversification as well as their ecological success in these
extreme environments are a combined result of their feeding and reproductive adaptations.
Long distance dispersal capabilities of Bathymodiolus species are inferred from observations
of small oocytes (40-80 µm), large embryonic shells (100-120 µm) and larval shells (380-520
µm), and also from their reproductive dynamics. Together this suggests a planktotrophic
larval phase that extends for five to six months. Other mytilid genera, Idas and Adipicola, are
found associated with decaying organic matter at wood- and whale-falls, yet their
reproductive biology and development is poorly studied. The evolutionary history of
chemosymbiotic mytilids has been extensively investigated using molecular approaches, but
their phylogenetic relationships are still not completely understood. Studies of morphological
characters of these mytilid genera are almost absent and are useful to improve the systematics
of Recent and fossil mytilids.
Bivalve larval and juvenile shell morphology provides important information for ecology,
biogeography, systematics and evolution. This study aims to investigate the potential use of
early ontogenetic features for phylogenetic analyses of mytilids, including chemosymbiotic
taxa. Larval and juvenile shells of vent, seep, wood and whale associated species were studied
using SEM and compared with representative non-chemosynthetic mytilid taxa.
Morphological features, such as size, shape, sculpture, coiling, hinge teeth and ligament pit,
were observed and used for phylogenetic reconstruction.
The results of this study give new insights into these main questions: do all chemosymbiotic
mytilids belong to one group? Who is the ancestor of this group? And do phylogenetic
relationships reveal adaptational pathways?
THE OCEAN IS NOT DEEP ENOUGH: PRESSURE TOLERANCES DURING
EARLY ONTOGENY OF THE BLUE MUSSEL MYTILUS EDULIS
Nélia C. Mestre, Sven Thatje and Paul Tyler
National Oceanography Centre, Southampton, School of Ocean and Earth Science, University of Southampton,
European Way, Southampton, SO14 3ZH, United Kingdom; email of presenting author: ncm1@noc.soton.ac.uk
Early ontogenetic adaptations reflect the evolutionary history of a species. To understand the
evolution of the deep-sea fauna and its adaptation to high-pressure, it is important to know the
effects of pressure in their shallow-water relatives. In this study we analyse the temperature
and pressure tolerances of early life history stages of the shallow-water species Mytilus edulis.
This species expresses a close phylogenetic relationship with hydrothermal-vent mussels of
the subfamily Bathymodiolinae. Tolerances to pressure and temperature are defined in terms
of fertilization success and embryo developmental rates in laboratory-based experiments. In
Mytilus edulis, successful fertilization under pressure is possible up to 500atm, at 10, 15 and
20 ºC. A slower embryonic development is observed with decreasing temperature and with
increasing pressure; principally, pressure narrows the physiological tolerance window in
different ontogenetic stages of M. edulis, and slows down metabolism. This study provides
important clues on possible evolutionary pathways of vent and cold seep bivalve species and
their shallow-water relatives. Evolution and speciation patterns of species derive mostly from
8th Larval Biology Symposium
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Ontogenetic strategies in extreme aquatic
environments
Oral
their capability to adapt to variable environmental conditions, within environmental
constraints, which promote morphological and genetic variability, often differently for each
life history stage. The present results support the view that a colonisation of deep-water
chemosynthetic environment by a cold-eurythermal shallow-water ancestor is indeed a
possible scenario for the Mytilinae.
RELATIONSHIPS BETWEEN GROWTH, DEGREE OF EURYHALINITY AND
OSMOREGULATION IN DECAPOD CRUSTACEAN LARVAE
Gabriela Torres1, Klaus Anger 2 and Luis Giménez 1
1
School of Ocean Sciences, Bangor University LL59 5AB, Menai Bridge, UK; email of presenting author:
g.torres@bangor.ac.uk
2
Biologische Anstalt Helgoland, Alfred-Wegener-Institute for Polar and Marine Research, 27498 Helgoland,
Germany.
We seek for general responses to salinity in larval growth, biomass and chemical composition
(protein, lipid) of twelve species of decapod crustaceans varying in euryhalinity and
osmoregulatory capabilities (from osmoconformers to strong osmoregulators). Data for seven
species were obtained from previous publications; those for five additional species are
reported for the first time. The biomass of euryhaline larval instars showed consistently a
weak response to salinity, even near the lower limits of salinity tolerance. Biomass of
stenohaline larval instars showed a higher sensibility to salinity variations, with strong
interspecific variability. The sensibility decreased with increasing osmoregulatory capacity.
Our data suggest that euryhalinity is associated with a reduced sensibility of metabolic and
growth processes to low salinity. The ability to osmoregulate buffers the internal medium
allowing the larvae to maintain a high growth rate. The energetic costs of osmoregulation in
larval decapods seem to be offset by the capacity of maintaining high growth rates in
physically variable environments.
REPRODUCTION AND EARLY DEVELOPMENT OF BONE-EATING OSEDAX
WORMS: PAEDOMORPHIC MALES RECRUITED FROM VAST LARVAL POOL
Robert C. Vrijenhoek1, Shannon B. Johnson1 and Greg Rouse2
1
Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, USA; email of presenting author:
vrijen@mbari.org
2
Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA
Bone-eating marine worms of the genus Osedax (Annelida: Siboglinidae) occur worldwide at
depths between 25 and 3000 m. The females host groups ("harems") of dwarf males in their
tubes and release streams of zygotes (in nature and in laboratory aquaria. Size variation exists
among the males in a harem, but the smallest males were nearly identical to metatrochophore
larvae that developed in laboratory aquaria. Osedax is hypothesized to employ environmental
sex-determination (ESD) involving two phases: (1) undifferentiated larvae that settle first on
8th Larval Biology Symposium
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Ontogenetic strategies in extreme aquatic
environments
Oral
bones develop as females; and (2) larvae that subsequently settle on females are transformed
into males. We could not test the ESD hypothesis experimentally, but we used population
genetic methods to examine several hypotheses regarding possible recruitment sources of
males. Samples of O. rubiplumus females from whalebones collected at in Monterey Bay,
California, clearly revealed that the males and associated host females were recruited from a
common larval pool. No significant partitioning of mitochondrial DNA diversity existed
between the two sexes or between subsamples taken during different years (2002–2007) or at
1820 and 2893 m depths. The absence of a co-ancestry component of genetic diversity among
the harems, clearly refuted alternative male recruitment hypotheses including arrhenotoky
(retention of haploid parthenogenetic males) and swamping by the sons of neighboring
females. Very high mtDNA diversity in these worms suggested that as many as 106 females
contributed to a vast larval pool from which the two sexes were randomly drawn. ESD
provides an efficient strategy for colonizing and reproducing on a patchy and ephemeral
resource such as scattered animal bones. If, on the other hand, genotypic sex-determination
and a 1:1 primary ratio exist in O. rubiplumus, the extreme sex ratios seen in adult worms
(600♂:1♀) would require massive shifts in mortality between the female and male
recruitment phases.
DENSITY, FLUX AND RECRUITMENT RATES OF OPPORTUNISTIC DEEP-SEA
LARVAE IN THE TONGUE OF THE OCEAN, BAHAMAS
Craig M. Young1, Roland H. Emson2, Mary E. Rice3 and Paul A. Tyler4
1
Oregon Institute of Marine Biology, University of Oregon. P.O. Box 5389, Charleston, OR 97420 U.S.A;
email of presenting author: cmyoung@uoregon.edu
2
Division of Life Sciences, Kings College London, Franklin-Wilkins Building, 150 Stamford St., London
SE19NN, U.K.
3
Smithsonian Marine Station at Ft. Pierce, 701 Seaway Dr., Ft. Pierce, FL 34949, U.S.A.
4 National Oceanography Centre, University of Southampton, Southampton, SO14 3ZH UK
Vascular plant materials such as wood and leaves are relatively rare substrata in the deep sea,
yet there exist specialized suites of organisms, including xylophagid bivalves, cocculinid
limpets and some sipunculans that specialize on these substrata. Rapid colonization of deepsea wood was first documented by Ruth Turner more than 40 years ago and has now been
observed in many places throughout the world. Such rapid colonization of rare substrata is
generally thought to involve an “r-selected” life-history strategy that might include high
fecundity, continuous reproduction, and rapid growth to reproductive maturity. Using a
submersible we deployed and recovered palm fronds, wood and fibrous door mats
approximately every three months for three years at slope depths in the Tongue of the Ocean,
Bahamas. By deploying current meters on the bottom during recruitment experiments, we
were able to calculate the minimal densities of competent larvae that would be required to
produce observed numbers of settlers. Recruitment rates of three cocculinid species, one
sipunculan species and one species of xylophagid bivalve were measured. All species settled
in every season of the year, but strong seasonal patterns were evident. The highest recruitment
rates could be explained by extremely low larval densities on the order of 10-5 to 10-3 larvae
m-3.
8th Larval Biology Symposium
Lisbon, 2008
Ontogenetic strategies in extreme aquatic
environments
Poster
COPPER EFFECT ON LARVAL CULTURE OF CARPET-SHELL CLAMS
(Ruditapes decussatus)
P. Ruiz-Azcona1, O. Moreno1, I. Palanco1, I. Martínez-Pita1, I. Giráldez2, A. Velasco2
and E. Morales2
1
IFAPA Centro “Agua del Pino”. Apdo.104. Huelva. España; email
mpaz.ruiz.ext@juntadeandalucia.es
2
Universidad de Huelva, Avda. Fuerzas Armadas s/n, 21071. Huelva. España.
of
presenting
author:
Carpet-shell clam Ruditapes decussatus (Linné, 1758) is a bivalve with high economic value
and interest for aquaculture on Southwest Spain coast. The effect of copper on larval of R.
decussatus was evaluated in aqueous laboratory assays. Larvae are less tolerant than adults to
pollutants and therefore, they represent the critical life stage for toxicity tests. On the other
hand, the usual concentration of copper (30 ppb) presents in water of Piedras River estuarine
can affect to larval culture of bivalve. The experimental culture has been carried out in one
and four litres of artificial seawater. Copper concentration (0, 30, 50, 100 and 200 ppb),
exposition time (48, 72 and 96 hours), mortality, lethal concentration (LC50) have been
studied. Larval mortality is 100% after 96 h when they were exposed at 100 ppb of copper.
Larval mobility decreases when they were exposed to concentration higher than 100 ppb for
48 and 72 hours. LC50 were 190, 97 and 49 ppb of copper at 48, 72 and 96 hours, respectively.
There were not significative differences in the copper concentration in the water for control
and 30 ppb of cooper, but there were significative differences (ANOVA; p<0,021) for the
other copper concentrations in this work.
8th Larval Biology Symposium
Lisbon, 2008
Ecology, recruitment and settlement
Oral
LARVAL MORTALITY DURING EXPORT TO THE SEA IN THE FIDDLER CRAB
UCA MINAX
R. Brodie1, R. Styles2, S. Borgianini3, J. Godley 3, and K. Butler4
1
Department of Biology, Mount Holyoke College, 50 College Street, South Hadley, Massachusetts, 01075; email
of presenting author: rbrodie@mtholyoke.edu
2
Department of Geological Sciences and Marine Science Program, University of South Carolina, Columbia,
South Carolina, 29208.
3
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, 29208.
4
University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, Maryland, 21201.
Dense populations of the fiddler crab Uca minax (Le Conte 1855) are common along tidally
influenced freshwater rivers and streams > 50 km from the sea. Adults do not migrate from
inland sites to release larvae, but instead release them directly into an environment where the
zoeae cannot survive. Laboratory salinity tolerance experiments were used to determine how
long larvae from the inland-most population of U. minax along the Pee Dee River, South
Carolina, USA can survive 0 salinity compared to larvae from a brackish water population
(salinity 5) near the mouth of Winyah Bay in the same estuary. Larvae from the brackish
water population were also exposed to a salinity of 5 and their survival tracked. To determine
if inland larvae suffered significant mortality in transit due to salinity stress, current profiles
were measured in the field and used to model the time taken by a larva using ebb-tide
transport to travel to permissive salinities. The laboratory tolerance experiments showed that
larvae from the inland freshwater population had LT50's of 4-5 d at 0 salinity, which were
significantly longer than those of the brackish water zoeae (2-3 d). Zoeae from the brackish
water population survived for at least one larval molt at a salinity of 5 with LT 50's of ~ 12 d.
Estimated travel times to reach permissive salinities from the inland-most population based on
current profiles were 3-5 d for larvae using night-time only ebb-tide transport and1.5-2.5 d for
those using ebb-tide transport both day and night. Pump sampling data from the Pee Dee
River indicate that U. minax zoeae travel during both day and night-time ebb tides, however,
more larvae are present in the water column at night.
DOES WAVE EXPOSURE AFFECT SEMILUNAR SYNCHRONISM OF LARVAL
RELEASE IN THE MOTTLED ROCKY SHORE CRAB?
M. Bueno1, A. C. A. Mazzuco2 and A. A. V. Flores3
1
Universidade de São Paulo. Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto. Avenida Bandeirantes
3900, CEP 14040-901, Ribeirão Preto, SP, Brazil
2
Universidade Federal Fluminense. Depto. de Biologia Marinha. Outeiro São João Batista, s/nº CEP 24001-970,
Niterói, RJ, Brazil
3
Universidade de São Paulo. Centro de Biologia Marinha. Rodovia Manoel Hipólito do Rego, Km 131,5, CEP
11600-000, São Sebastião, SP, Brazil; email of presenting author: guca@usp.br
The mottled shore crab Pachygrapsus transversus exhibits semilunar larval release in the
southeastern coast of Brazil, but preliminary observations on two populations exposed to
different wave action, suggest that such a rhythmic pattern is stronger at the more sheltered
site. It is known that hydrostatic pressure may entrain activity rhythms in other crab species
8th Larval Biology Symposium
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Ecology, recruitment and settlement
Oral
and, therefore, could affect synchronism of larval release in P. transversus. Since the
Brazilian coast is subject to microtidal regimes (max. 1.5 m in springs), wave exposure could
blur the tidal signal of hydrostatic pressure, and therefore affect synchronism of semilunar
larval release in natural populations. We selected three sheltered and three exposed rocky
shores, interspersed along a 50 km coastline and sampled egg masses of over 50 individuals at
all sites and at four different periods during a single breeding season. The embryos were
staged, and the day of release was estimated based on previous information on reproductive
females. Data were analyzed using a factorial ANOVA design with ‘wave exposure’ and
‘sampling period’ as fixed factors and shores nested within wave exposure. Individuals
sampled within shores allowed us to test for the consistency of shores over time (periods).
Results did not support the hypothesis of wave exposure and no significant variation was
observed among periods. Instead we found significant differences among shores within
exposure levels and a posteriori tests showed this variation was all found in exposed shores.
In sheltered shores crabs were highly synchronous. Thus, wave exposure might have variable
effects on synchrony in larval release, but its impact might be perceived in different ways by
different local populations. Further studies are suggested to determine the existence of
breeding sub-groups and variability at smaller spatial scales.
ENVIRONMENTAL DRIVERS SHAPING STOCHASTIC AND DETERMINISTIC
TEMPORAL PATTERNS OF PROPAGULE RELEASE IN BARNACLES AND
PERIWINKLES
M. Bueno1, G. A. O. Moser2, B. R. C. Tocci2 and A. A. V. Flores3
1
Universidade de São Paulo. Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto. Avenida Bandeirantes
3900, CEP 14040-901, Ribeirão Preto, SP, Brazil; email of presenting author: mbueno@pg.ffclrp.usp.br
2
Centro Universitário Monte Serrat, Faculdade de Ciências Ambientais, Oceanografia. Av. Rangel Pestana, 99,
CEP 11013-551, Santos, SP, Brazil.
3
Universidade de São Paulo. Centro de Biologia Marinha. Rodovia Manoel Hipólito do Rego, Km 131,5, CEP
11600-000, São Sebastião, SP, Brazil
Patterns of propagule release at small temporal scales may be either highly predictable or
quite irregular. Analytical tools and experiments are usually designed to detect rhythmic
behaviors according to well-known periodic factors, while other factors of more stochastic
nature are seldom explicitly considered. In this study, we used both spectral analyses and
ARIMA modeling to identify the main factors associated to spatially-consistent temporal
variability in propagule release in the barnacle Chthamalus bisinuatus and the periwinkle
Nodilittorina lineolata. The barnacle exhibited periodic naupliar release, with maxima at neap
tides. Wave height and salinity vary in phase with tidal amplitude and, therefore, they were
also negatively correlated to release rate. Opposite to expectations, density of the diatom
Skeletonema costatum did not trigger or enhanced release responses. In contrast, temporal
pattern of egg-capsule release in Nodilittorina was markedly irregular, and mirrored variation
of wave height. No other variables were apparently correlated with egg release in this species.
8th Larval Biology Symposium
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Ecology, recruitment and settlement
Oral
INFLUENCE OF LARVAL RETENTION AND ONSHORE SELECTION ON THE
DISTRIBUTION PATTERN OF THE ACORN BARNACLE TETRACLITA
JAPONICA JAPONICA
Damgy H. L. Chan1, Ling Ming Tsang2, K. H. Chu2, Benny K. K. Chan3 and Gray A.
Williams1
1
The Swire Institute of Marine Science and Division of Ecology & Biodiversity, School of Biological Sciences,
The University of Hong Kong, Pokfulam Road, Hong Kong; email of presenting author:
damgy@graduate.hku.hk
2
Department of Biology, The Chinese University of Hong Kong, Hong Kong
3
Research Centre for Biodiversity, Academia Sinica, Taiwan
The acorn barnacle, Tetraclita japonica japonica, is a common space occupier in the mid-high
shore of Japan, Korea and South China. The underpinning processes regulating the
distribution of this barnacle are poorly understood. The present study investigated the
population genetics of T. j. japonica using Fluorescent Amplified Fragment Length
Polymorphism (FAFLP), with specific focus on the genetic differentiation (FST) between the
northern (Japan and Korea) and southern (South China) populations, as well as the presence
of onshore, post-settlement selection on Hong Kong shores (southern populations). On a large
geographic scale, the northern populations were genetically distinct from the southern
populations. This divergence may be driven by the prevailing ocean currents, specifically the
Kuroshio Current influencing the northern populations and the South China Sea Current
influencing the southern populations. These different currents may form a barrier preventing
larval dispersal and, hence, gene flow between these populations. The detection of outlier loci
from the expected FST suggests potential divergent selection between northern and southern
populations. On a small geographic scale (within Hong Kong), new settlers of T. j. japonica
had higher genetic diversity than three-month-old recruits, but this reduction in genetic
diversity varied from site to site as did the FST between new settlers and three-month-old
recruits. These results indicate site-specific post-settlement selection on Hong Kong shores.
As a consequence, the distribution pattern of adult T. j. japonica is likely a result of the
combination of large-scale variation in larval supply onto the shores and the smaller scale
local onshore, post-settlement selection.
SUBSTRATE EXPLORATION BEHAVIOR OF MEMBRANIPORA MEMBRANACEA
LARAVE UNDER DIFFERENT FLOW VELOCITIES
Joanna Gyory and Colleen Petrik
Woods Hole Oceanographic Institution, Woods Hole, MA, U.S.A; email of presenting author: jgyory@whoi.edu
Most studies of settlement behavior look at the flow patterns around substrata and the
distributions of already-settled organisms to infer larval settlement preferences. Few studies
have attempted direct characterization of the substrate exploration behaviors of larvae, mainly
because of the difficulty in observing such small animals. We examined the settlement
8th Larval Biology Symposium
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Ecology, recruitment and settlement
Oral
behavior or Membranipora membranacea cyphonautes larvae from the coast of Friday
Harbor, Washington, USA. When these larvae encounter suitable kelp, they crawl upstream to
reach the youngest part of the blade. This ensures that their colonies will not be damaged on
the older, fraying end of the blade. To find the youngest part of the blade, the larva must
explore the substrate and detect the cues that signal the age of the kelp. Therefore, the ability
to explore is crucial in finding a good settlement site. We built a small racetrack flume in
which we filmed cyphonautes larvae as they explored pieces of kelp blades prior to settling.
We ran the flume at three different velocities to determine whether this would have an effect
on exploration behavior. The hypotheses we tested included: 1) The number of settlers would
be greater in low flow than high flow environments; 2) the proportion of larvae exhibiting
active versus passive exploration behaviors would be greater in low flow than high flow; and
3) active exploration behaviors would be interrupted more frequently in high flow. Our results
provide information about how hydrodynamic forces and larval behavior interact to determine
the settlement of Membranipora membranacea.
USE OF TIME SERIES TO MAKE A MECHANISTIC LINK BETWEEN
PLANKTONIC AND BENTHIC PROCESSES IN INTERTIDAL BARNACLES:
IMPLICATIONS FOR UNDERSTANDING CLIMATE CHANGE?
S R Jenkins1, H Sugden1, K De La Haye2, M Edwards3, N Halliday4 and S J Hawkins1
1
School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5AB, UK; email of presenting
author: s.jenkins@bangor.ac.uk
2
School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
3
Sir Alister Foundation for Ocean Science, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
4
Marine Biological Association., Citadel Hill, Plymouth PL1 2PB, UK
Climate change has had profound effects on various components of marine ecosystems
including planktonic assemblages. Whilst many studies have shown broad correlations of
organism abundance, timing of migrations or reproduction, with changes in temperature or
weather systems, such as the NAO, the processes involved have often not been well
established. The timing and magnitude of the spring phytoplankton bloom in temperate waters
has significant implications for zooplankton assemblages and the impacts of climate-change
forced mismatches has convincingly been shown for pelagic ecosystems. However, trophic
linkages between phytoplankton and benthic invertebrates through their meroplanktonic
larvae have been relatively neglected. Acorn barnacles are an important group in the
dynamics of intertidal systems and have made a superb model for studies of larval transport
and supply. They are also sensitive biotic indicators of responses to climate change. We reexamined archived plankton samples collected by the Sir Alister Hardy Foundation for Ocean
Science (SAHFOS) from the Irish and North Sea with the aim to investigate the relationship
between planktonic abundance of barnacle larvae, recruitment success and physical
environmental forcing factors. The early and late nauplius, and cyprid stages of 5 species of
intertidal and sub-tidal barnacles were enumerated from over 250 samples collected in the
spring time over a twenty-five year period (1980-2005). Physical environmental factors
including NAO showed some relationship with planktonic abundance but these were not
8th Larval Biology Symposium
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Ecology, recruitment and settlement
Oral
transferred to indicators of recruitment success. The lack of relationship between planktonic
larval abundance (at any larval stage) and intertidal recruitment success of Semibalanus
balanoides over large spatial scales indicates that factors affecting recruitment success may be
operating at more local scales. Other patterns in larval abundance indicate the importance of
occasional successful years in the persistence of benthic populations of northern species in the
face of climate change.
EFFECT OF VERTICAL PLANKTONIC DISTRIBUTION OF COMPETENT
LARVAE ON INITIAL SETTLEMENT IN THE INTERTIDAL ZONE: THE CASE
OF THE SOFTSHELL CLAM (MYA ARENARIA).
Landry Sonia and Miron Gilles
Département de biologie, Université de Moncton, Moncton, NB E1A 3E9, Canada; email of presenting author:
esl2644@umoncton.ca
The distribution of marine benthic invertebrates is influenced by numerous factors including
hydrodynamics. This particular factor affects the distribution and the behaviour of planktonic
larvae and thus their initial settlement position in the intertidal zone. The relationship between
the concentration of competent larvae in the water column and on the sediment surface has
been mainly studied for sessile species in hard-bottom habitats. Recruitment dynamic in softbottom habitats differs due to the instability of the substrate. This study quantifies the
relationship between larval concentration in the water column and on the sediment surface in
relation to the tidal level and the day/night cycle for the softshell clam (Mya arenaria). The
sampling was carried out in two tidally contrasted sites: Bay of Fundy (high amplitude) and
Northumberland Strait (low amplitude) both located along the coast of New Brunswick,
Canada. Planktonic and recently settled larvae were collected at three different water depths
and at three different intertidal levels. Preliminary results showed that the vertical distribution
of larvae is homogenous in the water column in the Northumberland Strait while larvae are
suprabenthic in the Bay of Fundy. The number of early-settlers does not vary with the tidal
level. Samples collected during the night contained more early-settlers than samples collected
during the day. This study will provide useful information on the recruitment process in an
intertidal soft-bottom environment and on the population dynamics of a species gaining
popularity in the aquaculture industry.
DISTRIBUTION OF OCTOPUS VULGARIS PARALARVAE
WESTERN IBERIA AND GULF OF CADIZ ECOSYSTEMS
WITHIN
THE
Ana Moreno1, Antonina dos Santos1, Uwe Piatkowski2, A. Miguel P. Santos1 and
Henrique Cabral3
1
Instituto Nacional de Recursos Biológicos-IPIMAR, Av. Brasília 1449-006 Lisboa, Portugal; email of
presenting author: amoreno@ipimar.pt
2
Leibniz-Institut Fuer Meereswissenschaften (IFM-GEOMAR), Universitaet Kiel, Duesternbrooker Weg 20, D24105 Kiel, Germany
8th Larval Biology Symposium
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Ecology, recruitment and settlement
Oral
3
Universidade de Lisboa, Faculdade de Ciências, Instituto de Oceanografia, Campo Grande, 1749-016 Lisboa,
Portugal
The differences between the Western Iberia and the Gulf of Cadiz oceanographic systems
induce quite different environmental conditions in the western and the southern Portuguese
waters, which potentially affect differently cephalopod paralarvae distribution and seasonality
in those areas, with significant implications on regional population structure. The distribution
and seasonality of Octopus vulgaris paralarvae off the Portuguese coast is analyzed based on
19 years of plankton sampling. The effects of several variables on paralarvae distribution are
analyzed with GLM models, for the whole area and separately for the western and southern
areas. Octopus paralarvae are very scarce in standard plankton hauls, which caught mostly the
first 10-12 days of the planktonic phase. Higher paralarvae densities occur mainly in the
second half of the year, with peaks in July and November in both areas. Overall, the
probability of finding paralarvae increase along the year (higher in autumn), with increasing
surface temperature (higher at 17-19 ºC), and decreasing latitude (higher in the south). The
influence of coastal upwelling conditions is rather different between the west and south
regions. On the west coast paralarvae distribution is highly correlated with upwelling
conditions, independently of hatching season, which is not observed on the south. Particularly
on the north-west coast, the distribution of paralarvae seems to agree well with the Ekman
dynamics of cross-shelf transport, showing higher densities offshore during the upwelling
season and near the shore during the convergence period. The complex water circulation of
this area, prevent paralarvae advection and loss into the open ocean during upwelling,
allowing favorable conditions for local extended spawning/hatching season. On the southern
Portuguese waters, the two density peaks of paralarvae are not in agreement with the typical
single peak of spawning of O. vulgaris of the northern Gulf of Cadiz. The hypothesis of
paralarvae drift from the west in summer within the upwelling jet around Cape St. Vincent is
discussed.
SPATIAL PATTERN OF BARNACLE RECRUITMENT OVER MULTIPLE SCALES
AT A ROCKY SHORE IN SOUTHERN HOKKAIDO, JAPAN
Daphne M. Munroe and Takashi Noda
Graduate School of Environmental Science, Faculty of Environmental Science, Hokkaido University, N10 W5
Sapporo, Hokkaido, Japan 060-0810; email of presenting author: munroe@ees.hokudai.ac.jp
Recently developed methods allow point patterns to be quantified and examined. Such
analysis of patterns of larval recruits at various spatial scales can help in identifying the
underlying ecological and biological processes determining their distribution. A rocky
intertidal plot (30 cm wide x 100 cm tall) in southern Hokkaido, Japan was cleared every
summer 2004-2007 from upper to lower intertidal. Barnacle (Chthamallus challengeri)
recruitment was recorded using 40 photographs (25cm2); 8 photographs per 20 cm horizontal
band of tidal height, 5 horizontal bands total, after a recruitment period of approximately 134
days. Locations of barnacle recruits were mapped and co-ordinates used to analyze
8th Larval Biology Symposium
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aggregation at scales from 0-2 cm using Ripley’s K statistic and Neighbourhood Density
Function (in both cases models assumed heterogeneity of first-order density) for each
photograph. Quadrat density counts at scales from 20 – 50 cm provided estimates of
aggregation using Morisita’s Standardized Index. Results showed that barnacle recruits
demonstrate ordered or maximum spacing up to a distance of approximately 6 mm. From 6
mm to 2 cm recruits show random spacing based on NDF, but ordered distribution based on
the Ripley’s K statistic. This discrepancy is likely a result of the cumulative nature of the
Ripley’s K statistic. At larger scales, Morisita’s Standardized Index indicated aggregation. In
conclusion, this result may be explained biologically by the trade off between maximizing
need for space at small spatial scales, however being constrained by copulation with
neighbours, thereby resulting in aggregation at scales larger than the maximum penis length.
REPRODUCTIVE TRADE-OFFS AND CARRY-OVER EFFECTS IN RESPONSE TO
ADULT FOOD AVAILABILITY IN WHELKS
N. E. Phillips1, J. van der Sman1, C. Pfister 2 and J. D. Aguirre-Davies1,3
1
Victoria University Coastal Ecology Laboratory and the School of Biological Sciences, P.O. Box 600, Victoria
University of Wellington, Wellington, New Zealand; email of presenting author: Nicole.Phillips@vuw.ac.nz
2
Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA.
3
Current address: School of Integrative Biology, University of Queensland, Brisbane, Australia.
Whelks are a useful model system in which to investigate life-history trade-offs in response to
adult conditions. They lay benthic egg capsules that hatch crawl-away juveniles, with speciesspecific strategies ranging from having a single relatively large hatchling per capsule (e.g.
Cominella virgata) to multiple, smaller hatchlings per capsule either without intracapsular
feeding (e.g. Cominella maculosa) or with it (e.g. Haustrum species). We used these focal
whelks species in both laboraotory and field studies to examine how adult food variability
affects reproductive trade-offs in hatchling size, hatchling number, and early juvenile growth
and mortality.
Across species, and from both the field and laboratory studies, hatchling size varied within
and among capsules, but not in response to adult food treatment or sites with different natural
levels of food availability. For species with multiple hatchlings per capsule, hatchling number
varied by up to 7- 8.5 fold among capsules, but not by site or adult food treatment. Thus,
variability in size and number of offspring was greatest within and among females, although
there was evidence that overall capsule number and capsule volume varied by adult food
conditions.
In the laboratory experiment, there were carry-over effects of maternal nutrition on hatchling
growth, but not survival. The duration of these maternal effects, and the degree to which they
interacted with juvenile food availability, varied by species. Differences in maternal influence
among species are likely to be alternative strategies used to balance the advantage of high
fecundity with the benefits of producing higher quality larger offspring.
SPATIAL AND DIEL LARVAL DISTRIBUTION DECAPOD LARVAE OFF THE
SOUTH COAST OF PORTUGAL
Lisbon, 2008
8th Larval Biology Symposium
Ecology, recruitment and settlement
Oral
Patricia N. Pochelon1, 2, Antonina dos Santos2 and Henrique Queiroga1
1
CESAM, Departamento de Biologia, Campus Univeristario Santiago, Universidade de Aveiro, 3810 Aveiro,
Potrugal; email of presenting author: ppochelon@ua.pt
2
Instituto Nacional de Recursos Biológicos- IPIMAR, Avenida de Brasilia s/n, 1449-006 Lisbon, Portugal
Larvae are critical in the crustacean life cycle as they are often the only dispersal stage.
Vertical migration, which is a widespread behavior in these larvae, controls the rate and
direction of horizontal dispersal. Knowing larval distribution and abundance is necessary to
predict location and size of the brooding population. In this study, spatial distribution and
abundance of the decapod larvae were assessed. Two week-long campaigns were conducted at
the end of January both in 2006 and 2007, respectively sampling 28 and 47 sites off the South
Coast of Portugal. Larvae were collected by oblique plankton hauls with a Longhurst-Hardy
Plankton Recorder (LHPR), which allowed the water column to be sampled into 25m strata
from the surface to 300m, as well as with Bongo nets from the surface to 200m. Preliminary
analysis indicated that in 2006, total decapod abundance was 2.52 Ind m-3. The most abundant
group represented was the Brachyura (75.34% of total decapod catch), followed by the
Caridea (14.31%) and Anomura (8.31%). In 2007 abundance was much lower (0.294 Ind m3
). Again, Brachyura was the most abundant group (83.73%), followed by the Anomura
(6.41%) and Dendrobranchiata (6.36%). However, in 2007 the coastal area was not sampled.
When distribution of Decapod was compared for offshore location off the Algarvian coast
only, both years had similar relative abundances for each group even though overall decapod
catch in 2007 was 51.01% less than in 2006. Both years, Monodaeus couchi was the most
abundant species, followed by Goneplax rhomboides. However, coastal species such as
Atelecyclus sp, Pilumunus sp, Processa sp and Philocheras sp that dominates in the 2006
campaign, were almost completely absent in the 2007, more offshore, campaign. In contrast,
Dendrobranchiata species, usually found further offshore were significantly more abundant in
2007 than in 2006.
DOES LARVIPHAGY
POPULATIONS?
AFFECT
THE
CONNECTIVITY
OF
MUSSEL
Francesca Porri, Tembisa Jordaan and Christopher D. McQuaid
Coastal Research Group, Department of Zoology and Entomology, Rhodes University, P.O. Box 94,
Grahamstown 6140, South Africa; email of presenting author: f.porri@ru.ac.za
Intertidal population dynamics are driven by a complex series of processes, including larval
supply and the possibility of larval predation by benthic animals such as filter-feeders. We
hypothesised that larviphagy could play a major role in the reproductive connectivity of
mussel populations by removing larvae as they attempt to settle in the adult habitat. We tested
hypotheses that consumption of mussel larvae by adults removes a significant proportion of
potential settlers and is influenced by settlement intensity and tidal state. Predation of mussel
larvae by adult mussels was investigated on incoming and ebbing tides during four spring
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tides by analysing the gut contents of adult Perna perna and Mytilus galloprovincialis
collected from the low mussel zone. Consumption rates were compared to estimates of
successful settler densities on natural beds. The results showed that mortality of competent
larvae through adult ingestion reaches up to 77% of potential settlers. Rates of larval
consumption were highest during months of intense settlement, suggesting that mussels feed
opportunistically, filtering a relatively fixed volume of water and removing particles,
including larvae, in proportion to their densities in the water. Rates of larviphagy were also
higher during receding than incoming tides. We suggest that this is due to changes in larval
density or, more probably, in adult filtration efficiency that are related to the state of the tide.
Despite significant effects of both tidal state and settlement intensity on rates of larval
ingestion, neither had a significant effect on the proportion of potential settlers removed.
During settlement more than half of all potential settlers are lost through larviphagy, with
potentially serious consequences for population maintenance. The results highlight the
paradoxical nature of the evolution of settlement mechanisms in mussels, which must balance
the advantages of settlement in habitats favourable to adults against the consumption of larvae
by adults.
FROM EGG TO JUVENILE: EFFECTS OF OFFSPRING SIZE, LARVAL
BEHAVIOUR AND SETTLER COMPETITION ON REPRODUCTIVE SUCCESS OF
SOLITARY ASCIDIANS
Marc Rius1, Dustin J. Marshall2, Charles L. Griffiths3,4, George M. Branch3 and Xavier
Turon5
1
Departament de Biologia Animal, Universitat de Barcelona, Av. Diagonal 645, 08028, Barcelona, Spain; email
of presenting author: marcriusvil@ub.edu
2
Centre for Marine Studies, University of Queensland, 4072, Queensland, Australia
3
Marine Biology Research Centre, Zoology Department, University of Cape Town, Private Bag X 03,
Rondebosch 7701, South Africa
4
Centre of Invasion Biology, Zoology Department, University of Cape Town, Private Bag X 03, Rondebosch
7701, South Africa
5
Centre for Advanced Studies of Blanes (CEAB, CSIC), Accés a la Cala S. Francesc 14, 17300 Blanes (Girona),
Spain
The role of the larval stage of benthic invertebrates in determining adult distribution and
abundance is not independent of factors that precede and follow the larval phase. Here we
present a study of the effects of several factors on reproductive success spanning the entire
early-life history of solitary ascidians. These factors were: (1) the effect of initial offspring
size, (2) the phototactic behaviour of larvae, (3) the effect of conspecific tunic extracts, and
(4) competition with conspecific and heterospecific settlers.
Offspring size effects were studied in Microcosmus squamiger. Larger eggs developed larger
larvae, and these in turn produced larger settlers, although most of the correlations were not
significant. Post-metamorphic survival in the field was higher in individuals that had greater
initial settler size. Overall, initial offspring size was a good predictor of subsequent
performance.
For the study of phototactic larval behaviour and the effects of the tunic extracts, we used 6
species. We found no differences in settlement rates when larvae were separately exposed to
8th Larval Biology Symposium
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Ecology, recruitment and settlement
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either light or to darkness, but when they could choose between these two treatments, most
species preferred darkness. Tunic extracts inhibited settlement of most species, suggesting
that larvae prefer places where intraspecific competition will be limited.
Finally, we examined interactions among settlers of an introduced ascidian (Styela plicata)
and a native species (M. squamiger) in SE Australia. We found that the presence of recently
settled S. plicata inhibited settlement of the larvae of M. squamiger, whereas the presence of
conspecifics did not affect settlement of either species. In the field, the presence of S. plicata
recruits significantly increased the post-metamorphic mortality of M. squamiger.
The results show that several factors affect each early-life stage of solitary ascidians. Thus,
analysing a single stage can be misleading. Future studies should include all phases from
fertilization to post-settlement.
CONSEQUENCE OF CHANGES IN CARBONATE CHEMISTRY ON THE
DEVELOPMENT OF THE SEA URCHIN PSAMMECHINUS MILIARIS LARVAE
Nadia Suárez-Bosche, Mario Lebrato, Débora Iglesias-Rodríguez, Darryl Green and
Nigel Eastwood
National Oceanography Centre, University of Southampton, European Way, Southampton, SO14 3ZH, UK;
email of presenting author: nesubo@soton.ac.uk
The increasing levels of CO2, as a result of anthropogenic activity cause a decrease in pH and
the saturation of calcium carbonate. These changes in water chemistry are expected to be
detrimental to marine organisms producing calcium biomineral during their life cycle.
Echinoderm larvae are among the most susceptible organisms to ocean acidification since
calcification occurs at the very early developmental stages. There are few studies testing the
impact of increasing carbon dioxide partial pressure on marine organisms, especially at the
early stages of development. We tested the effect of changes in carbonate chemistry caused
by ocean acidification in the sea urchin Psammechinus miliaris as model organism
representing ecologically important benthic calcified animal. We used present-day and two
projections for CO2 partial pressure to the years 2050 and 2100. Additionally, we tested the
effect of saturation state of calcium carbonate by using artificial seawater simulating values of
present-day and three projections for future climate scenarios. We report on the effects of
carbonate chemistry on larval physiology including calcification and discuss the results in an
evolutionary context.
THE EFFECT OF COASTLINE TOPOGRAPHY ON MUSSEL DISTRIBUTION
ACROSS LIFE-HISTORY STAGES: LARVAL SETTLEMENT AND BEYOND
Charles E. O. von der Meden1, Francesca Porri1, Johan Erlandsson2, Christopher D.
McQuaid1
1
Coastal Research Group, Department of Zoology and Entomology, Rhodes University, P.O. Box 94,
Grahamstown 6140, South Africa; email of presenting author: g04v5287@campus.ru.ac.za
2
Department of Systems Ecology, University of Stockholm, 106 91 Stockholm, Sweden
8th Larval Biology Symposium
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Ecology, recruitment and settlement
Oral
For sessile intertidal invertebrates with a pelagic life stage, coastline topography influences
both the pre- and post-settlement environments. Very broadly this occurs through topographic
effects on a combination of nearshore oceanographic dynamics including physico-chemical
factors, larval transport mechanisms and levels of wave exposure. Recent work has shown
that embayed shores, in particular, can be zones of retention with higher settlement and
recruitment rates, as well as being areas of greater adult abundance. This study describes the
adult distribution of two mussel species, Mytilus galloprovincialis and Perna perna, along a
single coastline encompassing multiple bays (11 sites) and open coast shores (11 sites). In
conjunction with the adult distribution, patterns of settlement and recruitment (summer and
winter) and post-settlement mortality (summer) are examined in order to understand better
topographic effects on early life stages. ‘Snap-shot’ levels of summer and winter wave
exposure were determined simultaneously over all sites and related to adult cover. Mean adult
cover of both species was found to be significantly greater in bays than on the open coast.
This distribution was well explained by significantly higher mean settlement and recruitment
rates of each species within bays mainly during summer months. Preliminary post-settlement
mortality results did not identify any topographic pattern; however these data are limited by
frequently low settlement. As expected, bay sites had lower wave forces and water flux values
than open coast sites, particularly in winter when these differences were statistically
significant. Thus, adult distribution was well explained by topographic effects on wave
exposure, and higher settlement and recruitment rates. These results clearly indicate a broadly
pervasive influence of topography on mussel populations from settlement into adult stages.
8th Larval Biology Symposium
Lisbon, 2008
Ecology, recruitment and settlement
Poster
DECAPOD LARVAE IN THE BALEARIC SEA (NORTH WESTERN
MEDITERRANEAN); A PRELIMINARY VIEW OF THEIR BIOGEOGRAPHY
Aina Carbonell1, Ramón Más1, Francesc Alemany1 and Antonina dos Santos2
1
Centre Oceanogràfic de Balears. Institut Espanyol d’Oceaonografia.Moll de Ponent s/n. 07015 Palma de
Mallorca. Spain; email of presenting author: ana.carbonell@ba.ieo.es
2
Inst. Nacional de Recursos Biológicos. L-IPIMAR. Av. de Brasília, s/n.1449-006 Lisboa. Portugal
Within the framework of a project directed to the study of tuna larval ecology, carried out by
the Spanish Oceanographic Institute five summer plankton surveys (2001-2005) were carried
out over an extended grid of stations off the Balearic Islands. Oblique (70-0 m depth) and subsurface plankton tows were performed at each station, using Bongo-60 (200 and 333 microns
mesh size) and Bongo 90 (505 microns mesh size) nets, respectively. Moreover, several
environmental parameters were registered by means of CTD casts. This sampling scheme has
allowed to explore the distribution and abundance of the larvae of decapods in the area. 41
samples from year 2001 (18) and year 2005 (23) have already been analysed. In total, 65
different taxa have been identified, most of them belonging to the groups: Dendrobranchiata,
Caridea, Anomura and Brachyura. The aim of this study is to contribute to the effective
management of marine resources acquiring knowledge on the ontogeny strategies and the
larval ecology in relation to physical and biological processes.
RAPID IDENTIFICATION AND SORTING OF MARINE LARVAE USING IN SITU
HYBRIDIZATION AND A LARGE-PARTICLE CELL SORTER
Elizabeth A. Hoaglund1, Christine M. Henzler2, Gretchen E. Hofmann1 and Steven D.
Gaines1,2
1
Department Ecology, Evolution and Marine Biology, University of California, Santa Barbara 93106; email of
presenting author: hoaglund@lifesci.ucsb.edu
2
Marine Science Institute, University of California, Santa Barbara 93106.
Here we present a method to rapidly identify and count marine larvae from environmental
samples. The direct sampling of larvae is useful for understanding patterns of larval
distribution and dispersal, including quantifying the delivery of larvae to a site, export of
larvae from a site, and validation of dispersal models. Larval identification and counting is
traditionally accomplished by eye with a microscope. However, identifying larvae to species
or genus level by eye is difficult to impossible, and manual counting prohibits addressing
many questions because the scale of required monitoring is labor intensive. In the novel
method proposed here, we use whole-organism fluorescent in situ hybridization (FISH) to
label specific species of marine larvae with a fluorescent DNA probe, and larvae are then
counted and sorted with a recently developed large-format cell sorter. With this method, we
provide a means to accurately identify larvae to species, reduce the amount of time required to
count larvae, and sort larvae for further work, such as genetic analyses of individual larvae.
We show preliminary success counting and sorting urchin and mussel larvae with our method,
and plan to extend this technique to a suite of additional species.
8th Larval Biology Symposium
Lisbon, 2008
Ecology, recruitment and settlement
Poster
SPATIAL AND TEMPORAL SIZE DISTRIBUTIONS OF SARDINE (Sardina
pilchardus) AND ANCHOVY (Engraulis encrasicolus) LARVAE IN THE GULF OF
CÁDIZ (SW SPAIN)
M. P. Jiménez, Z. Romero and I. Muñoz
Instituto Español de Oceanografía. Unidad Oceanográfica de Cádiz. CACYTMAR: Centro Andaluz de Ciencia y
Tecnología Marinas. Campus Universitario del Río San Pedro. -11510- Puerto Real. Cádiz; email of presenting
author: zeneida.romero@cd.ieo.es
Plankton samples were collected in monthly cruises in a coastal fringe limited by the mouth
of the Guadiana River and Barbate (Gulf of Cádiz, SW Spain), from January to December
2006. Sampling scheme was established in a grid of thirty stations located on 7 transects
quasi-perpendicular to the coastline. Sardine (Sardina pilchardus) and anchovy (Engraulis
encrasicolus) larvae were sorted, counted and measured. A total of 8399 larvae of sardine
were measured, oscillating between 7 larvae measured in September and more than 1500 in
April. Larvae of sardine ranged between 0.6 mm and 28.1 mm total length. The mean size
registered was 5.0 mm TL, except in September with 9 mm TL. The more expended range
was obtained in February. In this month, the larger larval was caugth (28.1 mm TL). The
larger larvae of sardine were caught in two stations located in the Guadalquivir River mouth.
A total of 5978 larvae of anchovy were measured in the study period, oscillating between 11131 larvae (February-June, respectively). Anchovy larvae length ranged between 1.0 mm
and 25.6 mm TL. The mean size oscillated between 3.5 mm from January to August (except
in May, with 4.5 mm mean size) and also near to 4.5 mm from September to December.
Larger larvae were located in the Guadalquivir and Guadiana River mounths and near to
Conil. The more expended range of sizes was obtained in December and the larger larval was
observed in May (25.6 mm TL) This study is part of the project “Fluctuaciones y
potencialidad de especies pesqueras de plataforma en la Región Atlántica Andaluza” of the
Junta de Andalucía.
ABUNDANCE AND SPATIAL DISTRIBUTION OF PHYLLOSOMA LARVAE OF
SCYLLARUS SPP. (CRUSTACEA: DECAPODA) IN THE NW MEDITERRANEAN
Sandra Mallol, Francisco Alemany, David Díaz and Raquel Goñi
Centro Oceanográfico de Baleares. Instituto Español de Oceanografía. Muelle de Poniente s/n, 07015 Palma de
Mallorca; email of presenting author: sandra@ba.ieo.es
In the Mediterranean Sea phyllosoma larvae belong to 6 species from 4 genera within the
Decapod families Scyllaridae and Palinuridae. There is currently little knowledge on the
taxonomy, biology and ecology of phyllosma stages from these families. This study, based on
zooplankton samples caught off the Balearic Islands between 2001 and 2005, is the first to
document the abundance and spatial distribution of phyllosoma larvae in NW Mediterranean
8th Larval Biology Symposium
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Ecology, recruitment and settlement
Poster
waters. In each annual survey, carried out in June-July, we sampled a regular grid of about
200 stations each 10 nautical miles apart. Quantitative double-oblique plankton tows were
carried out at each station between 70 m depth to the surface with Bongo 60 nets fitted with
333 micron mesh, as well as CTD casts from 300 or 650 m to the surface. Moreover, in the
2001 and 2002 surveys, additional plankton samples were obtained at the intermediate points
between stations by means of subsurface tows carried out with Bongo 90 nets equipped with 2
mm mesh. A total of 417 phyllosoma larvae of genus Scyllarus were identified from the
Bongo 60 and 90 samples, with the notable absence of any members of the family
Palinuridae. Specimens from 2004 and 2005 surveys (82 individuals) were measured (total
length, carapace length and carapace width) and their developmental stage was determined in
order to define morphotypes, as a first step to classify them at species level. We discuss the
abundance and distribution of such Scyllarus sp. phyllosoma larvae in relation to mesoescale
hydrographic features and environmental variables.
SEASONAL PATTERN OF MYTYLUS GALLOPROVINCIALIS SETTLEMENT
RELATED TO ENVIRONMENTAL CONDITIONS IN RÍA DE ARES-BETANZOS
(NW-SPAIN)
Laura G. Peteiro, Ramón Filgueira, Silvia Piedracoba, Xose Antón Álvarez-Salgado,
Gabriel Rosón, Uxío Labarta and María José Fernández-Reiriz
Consejo Superior Investigaciones Científicas, Instituto de Investigaciones Marinas, C/Eduardo Cabello, 6, Vigo.
Pontevedra. CP. 36208, Spain; email of presenting author: lpeteiro@iim.csic.es
The onset, duration and intensity of mussel larvae settlement exhibit considerable spatial and
temporal variations. These variations have been attributed to several biotic and abiotic factors.
The timing and magnitude of larval supply are the most important biotic factors. Among the
abiotic factors, the local hydrographic regimes involved in nutrient and larval dispersion, and
local physico-chemical attributes are notable. In the present study, we assessed seasonal
settlement pattern of Mytilus galloprovincialis in a mussel cultivation location, Arnela, in the
Ría de Ares-Betanzos (NW Spain) between September 2006 and December 2007. Three ropes
were fortnightly hung from August 2006 to November 2007. The ropes were covered with
jute to facilitate the sampling of recently settled larvae. Previous studies seem to indicate a
minimum submerged time required to optimize the mussel seed yield on artificial collectors
about 45 days, so when new ropes were hung, ropes submerged for 45 days were sampled.
The mussels were detached from the jute using dilute bleach and ultrasonic bath treatment,
then dried and counted using a binocular microscope. Physico-chemical parameters
(temperature, salinity, dissolved oxygen, pH), chlorophyll content and seston quality and
quantity were measured weekly. Larval abundance index were provided by periodical
publications of INTECMAR.
Seasonal pattern was discussed in terms of the larval abundance and environmental
parameters. The results showed an annual seasonal pattern in which two settlement events
were observed. In spring-summer was observed the main peak, which begun in later April
with a maximum in later May and extended until August. In autumn, a smaller and shorter
event was recorded in both years (2006 and 2007). In 2006 the autumn event took place
earlier than in 2007 maybe due to the warmer autumn of that year. Temperature seems to be a
8th Larval Biology Symposium
Lisbon, 2008
Ecology, recruitment and settlement
Poster
trigger parameter that allows the onset of settlement events when pediveliger larvae are
abundant in the area. In this way, no settlement was observed with sea water temperatures
below 15ºC and a positive correlation was observed between settlement density and
temperature. On the other hand, chlorophyll content seemed to be another important factor for
mussel settlement in the area.
SPATIAL
VARIATION
IN
SETTLEMENT
PATTERN
OF
MYTILUS
GALLOPROVINCIALIS IN THE RÍA DE ARES-BETANZOS (NW-SPAIN) IN YEARS
2006/2007
Laura G. Peteiro, Silvia Piedracoba, Ramón Filgueira, Xose Antón Alvarez-Salgado,
Gabriel Rosón,Uxío Labarta and María José Fernández-Reiriz
Consejo Superior Investigaciones Científicas, Instituto de Investigaciones Marinas, C/Eduardo Cabello, 6, Vigo.
Pontevedra. CP. 36208, Spain; email of presenting author: lpeteiro@iim.csic.es
The spatial and temporal variability of mussel settlement patterns has been attributed to
several biotic and abiotic factors involved in both larval dispersion and settlement.
Monitoring larval settlement and recruitment in both natural and artificial substrata is an
important tool for assessing the population dynamics of commercial species. In the present
study, we have assessed settlement magnitude of Mytilus galloprovincialis in four mussel
cultivation locations (Lorbé, Arnela, Redes and Miranda) in the Ría de Ares-Betanzos (NW
Spain) after the main spawning event during spring 2006 and 2007. In each location, three
ropes were hung fortnightly from the first week of February 2006/2007 to the first larval
settlement event (end of April). When new ropes were hung, ropes submerged for 45 days
(minimum time required to optimize the mussel settlement on artificial collectors) were
sampled. The ropes were covered with jute to facilitate the sampling of recently settled larvae.
The mussels were detached from the jute using dilute bleach and ultrasonic bath treatment,
then dried and counted using a binocular microscope.
No significant differences were observed in the settlement density values in the Ría de AresBetanzos between years (ANOVA; p=0.487), although significant differences between
locations were detected (ANOVA; p<0.001). In 2006, the inner location in the south coast,
Arnela, showed the highest density values whereas in 2007, Miranda, located in the most
seaward area of the north coast, showed the highest densities. The results of the present study
seemed to indicate a stable temporal settlement in the Ría although the spatial pattern was not
maintained between years. The differences in settlement densities between locations and years
were discussed in terms of seston quantity and quality as well as local physical conditions.
DISTRIBUTION PATTERN OF THE COMMON OCTOPUS (Octopus vulgaris)
PARALARVAE ABUNDANCE IN THE GULF OF CADIZ (SW SPAIN).
CHARACTERIZATION OF THE NURSERY HABITAT.
Z. Romero, M. P. Jiménez and I. Muñoz
8th Larval Biology Symposium
Lisbon, 2008
Ecology, recruitment and settlement
Poster
Instituto Español de Oceanografía. Unidad Oceanográfica de Cádiz. CACYTMAR: Centro Andaluz de Ciencia y
Tecnología Marinas. Campus Universitario del Río San Pedro. -11510- Puerto Real. Cádiz; email of presenting
author: zeneida.romero@cd.ieo.es
The common octopus (Octopus vulgaris) is littoral specie with a planktonic posthatching
stage termed paralarval by Young and Harman (1998). Plankton and hydrological samples
were collected in monthly cruises in a coastal fringe limited by the mouths of the
Guadalquivir and the Guadiana Rivers (Gulf of Cádiz, SW Spain), from May 2005 to April
2007, in a grid of thirty stations located in 7 transects quasi-perpendicular to the coastline.
Spatial and temporal variation of the octopus paralarvae abundance were analysed during this
period. In addition, the correlation between biological and physical parameters (zooplankton
biomass, temperature, salinity, depth and distance to the coastline) and the octopus paralarvae
densities were explored by a pairwise Spearman index correlation analysis. The
characterization of the nursery habitat was carried out by the quotiens plots, and three
parameters were used: Temperature and Salinity, both to 5 m depth, and depth. This technique
provides an easy to implement tool to characterize the spawning and nursery habitats in
relation to biological and physical parameters (Van der Lingen et al., 2005). A total of 45
paralarvae were caught. The maximum abundance values were observed in November and
December 2005 (35 and 17 paralarvae/100m3, respectively). In 2006, the higher value was
observed in June (13 paralarvae/100m3). Octopus paralarvae abundance was negatively
correlated with all the environmental parameters analysed. The octopus paralarvae showed a
clear preference for areas where the water temperature was 17.5 ºC, approximately. In regard
to the depth, octopus paralarvae were located in all the area, but the 93% of them occurred at
bottom depth of 100 m. This study is part of the project: “Fluctuaciones y potencialidad de
especies pesqueras de plataforma en la region atlántica andaluza” of the Junta de Andalucía.
DISTRIBUTION PATTERNS OF DECAPOD LARVAE ABUNDANCE IN THE BAY
OF CASCAIS, PORTUGAL
Carla Santinho1, Joana Cruz1, A. Miguel P. Santos1, João Pastor1, Margarida Castro2
and Antonina dos Santos1
1
IPIMAR- Instituto Nacional de Recursos Biológicos, Av. Brasília, s/n, 1449-006 Lisboa, Portugal; email of
presenting author: carla.santinho@gmail.com
2
CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
The description of the decapod crustacean larval fauna in the Bay of Cascais, as well as their
abundance patterns, were analyzed taking into consideration the relationship with
environmental conditions such as: temperature, salinity, coastal upwelling and rain, with the
objective of contributing to the understanding of recruitment mechanisms in benthonic
invertebrates in the Portuguese coast. Monthly samples of zooplankton were collected at a
fixed location in the Bay of Cascais (38º40' N; 09º26'.20 W) with a depth of about 35 m, from
February 2005 to June 2007. The samples where collected 1-2 hours before high tide using
two types of nets and sampling strategies: neuston (mesh size 333 µm), towed horizontally at
the surface for 5 min, covering a layer of about 20 cm, and WP2 (mesh size 200 µm) towed
obliquely from a depth of approximately 35 m to the surface. The data were analyzed through
non-parametric correlations that revealed no relationship between larval abundance and
8th Larval Biology Symposium
Lisbon, 2008
Ecology, recruitment and settlement
Poster
environmental parameters. However, there were significant differences in the abundance of
zoeas between sampling nets, while no significant differences were found for the megalopae.
Decapods represented 2 to 38% of the zooplankton in the neuston net and 15 to 40% in WP2;
68 species were identified, the majority belonging to the three major groups: Caridea,
Anomura and Brachyura. Of these, the most abundant species were: Processa nouveli,
Diogenes pugilator, Carcinus maenas e Liocarcinus spp. Most decapods have their larval
emission peak during the early spring (e.g. P. nouveli, Pagurus spp., Pisidia longicornis,
Atelecyclus rotundatus, C. maenas, Liocarcinus spp., N. puber and P. hirtellus). Some, such
as E. ocultus, T. cranchii, Philocheras spp. and D. pugilator, have their larval emission peak
in summer.
MEROPLAKTONIC LARVAE IN THE SHIPS’ BALLAST WATER OF THE
NOVOROSSIYSK PORT OF THE BLACK SEA
J. P. Selifonova
Murmansk Marine Biological Institute, Kol’ski Scientific Center, Russian Academy of Sciences, Vladimirskaya
str., 17 Murmansk 183 010, Russia; email: Selifa@mail.ru
Meroplanktonic larvae of bottom invertebrates have the greatest chances for setting in ballast
water of commercial ships, in which not only single specimens but whole plankton
communities can be transported. In sample collected from the ballast water tank on board the
tanker “Prosky” that called of Novorossiysk on the Russia coast of the Black Sea, after sailing
from Thessaloniki, Greece, meroplanktonic larvae of polychaete and molluscan the not Black
Sea origin were found. The tank had been filled in the port of Thessaloniki and came to the
port of Novorossiysk to be loaded with oil products on 27 April 2004. Population of
meroplanktonic larvae were presentation by genera Microspio, Pygospio, holoplanktonic
polychaete (3.5 103 ind/m3) and cardiids (1·103 ind/m3). The examined organisms were
seemingly in good conditions indicating, that they were alive during preservations. It follows,
if ballast tank volume is 18.600 m3, each tanker of a similar type may transport 85 million
specimens of meroplanktonic larvae. High possibility of invasions a new species in the
Novorossiysk port is due to the fact that its water significant eutrophication and mesohaline
(12.9-16.9‰). Finding of new polychaete Streblospio sp. (family Spionidae) in the
Novorossiysk port testifies to the possibility of anthropogenic introduction by ships benthic
fauna in Black Sea (Murina et. al., 2008). The presence the polychaete family Spionidae was
first found in the Novorossyisk port in 2001 by Melnik (Melnik, 2002). This tiny worm (< 10
mm) inhabits the upper layer of muddy substrates estuary of the Tsemes River. Development
of polychaete of Streblospio proceeds through larval and juvenile stages (Myers, 1997). This
gives ground to suppose that at the discharge of ballast water in the port-recipient on the
Russian coast of the Black Sea, meroplanktonic larvae are well to establish maternal
population.
PHENOTYPIC PLASTICITY IN SEA URCHIN LARVAE: ECHINOPLUTEUS VS.
ECHINOPLUTEUS TRANSVERSUS
8th Larval Biology Symposium
Lisbon, 2008
Ecology, recruitment and settlement
Poster
N. Soars, T. Prowse and M. Byrne
Department of Anatomy and Histology and Bosch Institute, F13, University of Sydney, NSW 2006, Australia;
email of presenting author: mbyrne@anatomy.usyd.edu.au
Echinoid larvae are well known for their phenotypically plastic response to different food
regimes. Under laboratory conditions these larvae demonstrate and increase in postoral arm
length when food is limited, but a shorter postoral arm length and time to metamorphosis
when food is abundant. This increase in postoral arm length results in an increase in larval
feeding capacity through elongation of the ciliated band that runs along the arms, and an
increase in surface area: volume ratio (Strathmann, 1971; Manahan et al., 1983). This
response is thought to be an indication that there is a priority to allocate energy to feeding
structures before development of the adult rudiment (Strathmann, 1971) thus reducing the
time spent in the plankton exposed to predators (Boideron-Metairon, 1988). However, these
studies have been performed on a limited suite of species, most from the northern hemisphere
and all with a typical 8-armed larva. We tested 2 Australian species occurring in Sydney: one
an Echinometrid with a typical 8-arm echinopluteus (Heliocidaris tuberculata) and one a
Diademid with an atypical 2-armed echinopluteus transversus larva (Centrostephanus
rodgersii). While the 8-armed larvae demonstrated a typical phenotypic response, the 2-armed
echinopluteus transversus type larvae of C. rodgersii did not. This is the first time that a
Diademid has been tested for phenotypic plasticity in arm growth and the first time an
echinoid larva has not demonstrated a response. These findings have implications for the
generality of phenotypic plasticity of arm growth in echinoid larvae and the development
strategy of the 2-armed form.
Lisbon, 2008
8th Larval Biology Symposium
Genetics and physiology
Oral
INFLUENCE OF TEMPERATURE AND FOOD ON LARVAL GROWTH IN THE
NORWAY LOBSTER, Nephrops norvegicus
I. Álvarez-Fernández1, P. Verisimo1, L. Fernández1 and K. Anger2
1
Departamento de Bioloxía Animal, Bioloxía Vexetal e Ecoloxía, Universidade da Coruña, Campus da
Zapateira s/n, E-15071 A Coruña, Spain; email of presenting author: ialvarez@udc.es
2
Biologische Anstalt Helgoland, Stiftung Alfred Wegener Institute for Polar and Marine Research, Helgoland,
Germany
The aim of the present study was to analyse growth differences in Norway lobster larvae,
Nephorps norvegicus. To date very few studies have used nucleic acids and protein contents
to characterize larval stages in crustaceans. DNA, RNA and protein contents were quantified
and used as potential indirect measures of growth. Fed and starved larvae were reared at
different temperatures (6º, 12º, 18ºC) from hatching to the end of stage III (metamorphosis).
During this time, larval growth was measured in samples taken every 1-4 days as a function of
day-degrees. Growth was significantly higher in fed larvae compared to starved larvae at 12º
and 18ºC, while no significant differences were observed at 6ºC. Starved individuals did not
pass through the first moult. Duration of the larval moult-cycle varied with temperature. Stage
III was reached during the third week at 18ºC, while it took five weeks at 12ºC. The
RNA:DNA ratio and the protein:DNA ratio appeared to be viable indicators of growth in
Norway lobster larvae.
EFFECTS OF LOWER SEAWATER PH ON SEA
IMPLICATIONS FOR FUTURE OCEAN ACIDIFICATION
URCHIN
LARVAE:
D. Clark, M. Lamare and M. Barker
Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand; email of presenting
author: miles.lamare@otago.ac.nz
Ocean acidification, as a result of increased atmospheric CO2, is predicted to lower the pH of
seawater to between pH 7.5 and pH 7.7 over the next 100 years. The greatest changes are
expected in polar waters. Our research aimed to examine how echinoid larvae are affected by
lower pH, and if effects are more pronounced in polar species. We examined the effects of
lower pH on echinoid larvae from tropical (Diadema savigyn, Tripneustes gratilla,
Echinometra matheii), temperate (Pseudechinus huttoni, Evechinus chloroticus), and a polar
species (Sterechinus neumayeri) using a series of laboratory experiments. Larvae were reared
in a range of lower pH seawater (pH 6.0. 6.5, 7.0, 7.5, 7.7 and 8.1), adjusted by bubbling CO2
gas. The effect of pH on somatic and skeletal growth, calcification rate, development and
survival were quantified, while SEM examination of the larval skeleton provided information
on the effects of seawater pH on the fine-scale skeletal morphology (Fig. 1). Lowering pH
resulted in a decrease in survival, growth, calcification rate and skeletal structure, although
significant effects tended to be restricted to pH levels lower than 7.5. Contrary to
expectations, the polar larvae did not demonstrate a higher sensitivity to lower pH when
compared with non-polar species.
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Oral
DEVELOPMENT OF AMINERGIC CELLS AND EFFECTS OF POSSIBLE AMINEMIMICKING ALGAL TOXINS IN LARVAL CLAMS
Roger P. Croll1, Joseph Duffy2 and V. Monica Bricelj3
1 Dept. Physiol. & Biophys., Dalhousie Univ., Halifax, NS Canada; email of presenting author:
Roger.Croll@Dal.Ca
2 National Research Council of Canada, Institute for Marine Biosciences, Halifax, NS, Canada
3 National Research Council of Canada, Institute for Marine Biosciences, Halifax, NS, Canada; Present address:
Institute of Marine & Coastal Sciences, Rutgers Univ., New Brunswick, NJ, USA
The first serotonin-containing neurons develop early in the hard clam, Mercenaria
mercenaria, appearing in the apical organ by 2 days post-fertilisation (dpf). At this point,
larvae show a dose-dependent response to bath applications of serotonin by moving upward in
the water column, presumably due to accelerated swimming. No change in vertical position
occurs following application of the catecholamine, dopamine, at this stage. By 8 dpf,
however, catecholamine-containing cells can be detected in the velum and bath applications
of dopamine at 10-5M result in downward movements in the water column, presumably due to
slower swimming. At 12 dpf, as larvae attain metamorphic competence, additional serotonincontaining neurons are found in posterior ganglia. Larvae, however, are less sensitive to
serotonin than at earlier stages. At this point, larvae have numerous catecholamine-containing
neurons in the velum and continue to be sensitive to dopamine. Thus, this study is one of few
to examine the development of the nervous system in bivalves and is the only study to date to
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Oral
determine early ontogenetic changes in response to monoaminergic transmitters. Such
observations also permit testing hypotheses regarding possible amine-mimicking effects of
algal-toxins on developing bivalve larvae. Specifically, blooms of Aureococcus
anophagefferens are responsible for brown tide along mid-Atlantic estuaries of North
America. Brown tides have been implicated as a cause for decreasing abundance of native
bivalves, possibly through dopamine-mimicking actions on gill lateral cilia of adults, and are
known to reduce growth of clam larvae. When larvae were reared on toxic and non-toxic
stains of brown tide and exposed to these diets during swimming trials, we observed no
effects of A. anophagefferens on either the distribution of aminergic cells nor upon the
vertical position of M. mercenaria larvae during development. The actions of brown tide on
the larval biology of hard clams therefore remain unclear.
INTERPRETING THE POPULATION GENETIC STRUCTURE OF CARCINUS
MAENAS POPULATIONS ALONG THE IBERIAN COAST: LARVAL DISPERSAL
AND OCEANOGRAPHIC VARIABILITY
Carla P. Domingues1,2, Simon Creer2, Martin Taylor2, Henrique Queiroga1and Gary R.
Carvalho2
1
CESAM & Department of Biology, University of Aveiro, 3810-193 Aveiro, Portugal; email of presenting
author: cdomingues@ua.pt
2
Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, Environment Centre
Wales, Bangor University, Bangor, LL57 2UW, United Kingdom
Dispersal, gene flow and recruitment remain some of the most mysterious parameters in
population and conservation biology in the marine environment. Now, latest advances in the
utilization and analysis of molecular markers are revolutionizing the study of dispersal and
colonization. The aim of our work was to assess the spatial scale and the mechanisms of
connectivity of local populations of the shore crab Carcinus maenas. It is a species with a
planktonic larval phase that forms large populations in European estuaries and coastal waters,
and has become a global invader in several regions around the world. During the larval
season, several discontinuous events of larval supply to the estuaries can be detected that are
related to physical oceanographic processes. The first phase is to establish the population
genetic structure of adult C. maenas from along the western Iberian coast, and subsequently to
test predictions on connectivity generated by oceanographic data. Based on information from
microsatellite markers, we have assessed, over two years, the levels of population
differentiation and tested the hypothesis of isolation by distance of 14 estuarine populations of
C. maenas that spread along a geographic gradient from Ria de Navia, North Spain, to Ria
Formosa, South Portugal. Our study provides detailed data on the genetic structure of C.
maenas along the western Iberian coast and leads to important insights in understanding the
patterns of gene flow and its relation with larval behaviour and ocean circulation.
SEASTAR BINDIN
Michael Hart1, Susana PatiÒo1, Jan Aagaard2 and Willie Swanson2
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Oral
1
Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada; email of
presenting author: mwhart@sfu.ca
2
Department of Genome Sciences, University of Washington, Seattle, WA 98195-5065, USA
We describe early results from characterization of gamete recognition genes and their
evolution in asterinid sea stars. Variation in asterinid mating systems and larval dispersal
should affect sexual conflict, hybridization, and other processes that shape the evolution of
gamete recognition molecules in sea urchins and other animals. We used sequences from a
testis cDNA library supplemented by RACE and PCR methods to obtain a nearly complete
cDNA sequence (3500 bp) for the sperm acrosomal protein bindin from the broadcast
spawning Pacific species Patiria miniata. The N-terminal sequence is weakly similar to sea
urchin preprobindin and to vertebrate Slit glycoprotein ligands. The middle half of the gene
forms long (>100 bp) and short (18 bp) repeated domains analogous to sea urchin bindin
repetitive domains in which copy number varies among species. Pairwise divergence among
most of the long repeats is consistent with neutral variation (average dN/dS = 0.4), but one
domain is highly divergent from some others (dN/dS = 2.7-3.4). Additional repetitive
domains may be missing from our partial sequence (predicted MW = 100 kD). The P. miniata
cDNA lacks the RKKR cleavage motif that separates the N-terminal sequence from the
mature bindin in sea urchins; the mature P. miniata protein is correspondingly much larger
(130 kD) than in sea urchins (22-25 kD). The C-terminal sequence encodes a core domain of
35 residues that was nearly identical with part of the invariant core domain of sea urchin
bindin. The last long repeat and the core domain are separated by about 200 bp of nonrepetitive coding sequence (which may correspond to the ‘hot spot’ of rapid non-synonymous
substitutions between sea urchin species) plus an intron. The C-terminal sequence ends 15 bp
from the stop codon (without the highly variable polyglycine repetitive region of sea urchin
bindin), followed by a 700 bp 3’ UTR.
DECAPOD CRUSTACEAN LARVAE FROM EASTERN SCOTLAND (UK) AND
APPLICATION OF REAL-TIME PCR IN THEIR IDENTIFICATION
M. Pan1, A. J. A. McBeath1, S. J. Hay1, G. J. Pierce2 and C. O. Cunningham1
1
FRS Marine Laboratory, PO Box 101, Victoria Rd, Aberdeen AB11 9DB, United Kingdom; email of
presenting author: m.pan@marlab.ac.uk
2
Oceanlab, University of Aberdeen, Main Street, Newburgh, Aberdeenshire, AB41 6AA, United Kingdom.
Current address: Instituto Español de Oceanografía. Centro Oceanográfico de Vigo. P.O. Box 1552, 36200.
Vigo, Spain
Seasonal and interannual patterns of decapod crustacean larvae have been investigated in a
coastal monitoring station off eastern Scotland (UK). The plankton samples, collected over 4
and a half years were analysed and decapod larvae identified, except infraorder Brachyura.
The difficulty of obtaining information on this infraorder led to the application of real-time
PCR as a complementary tool for the accurate identification of brachyuran species, in
particular for the polybiinae species Liocarcinus depurator. This technique allowed the
identification and relative quantification of these larvae from monthly plankton samples
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Oral
collected through a 20 month period. These results were then compared with the seasonal
patterns of total decapod and brachyuran larvae obtained by the conventional plankton
analysis. The advantages and disadvantages of this molecular technique are discussed.
ROLE OF MULTIPLE PATERNITY IN CAUSING VARIATION IN LARVAL
GROWTH RATES IN THE GASTROPOD CREPIDULA FORNICATA
Jan A. Pechenik1, Sabrina Le Cam2, Mathilde Cagnon2 and Frédérique Viard2
1
Biology Department, Tufts University, Medford, MA 02155 USA; email of presenting author:
jan.pechenik@tufts.edu
2
Lab. Adaptation & Diversité en Milieu Marin (UMR 7144 CNRS UPMC), Station Biologique de Roscoff,
place Georges Teissier BP74, 29682 ROSCOFF cedex, France
The gastropod Crepidula fornicata has a long-lived larval stage that feeds on phytoplankton.
During development, the larvae grow from about 400-450 µm to about 1000 µm in shell
length, with the rate of growth varying markedly even among individuals from a single hatch
from a single female. Some of that variation might be due to a familial component associated
with multiple paternity, which is commonly observed in this species. To test that hypothesis,
we reared the larvae from 4 females for about 1 week and then measured about 40 of the
smallest (i.e., slowest-growing) individuals and about 40 of the largest (i.e., fastest-growing)
individuals from each of the 4 batches and preserved each larva separately for genetic
analysis. We also preserved all of the conspecific adults associated with each female.
Paternity analyses based on microsatellite genotyping were then used to determine who
fathered the larvae from each of the 2 categories. Among the 4 sampled females, most of the
offspring were convincingly assigned to a male that was physically associated with the mother
at the time of collection except in one family in which an unsampled individual fathered half
of the larvae. The larvae sampled from each female had from 2-4 different fathers, most of
which contributed to producing both fast and slow growing larvae. However, most of the
fathers produced primarily either fast-growing larvae or slow-growing larvae. These results
suggest that multiple paternity in this species may increase the range of larval growth rates
among siblings. To the extent that growth rates correlate with time to metamorphic
competence, multiple paternity might contribute also to a larger range of planktonic periods
and dispersal distances for sibling larvae.
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Poster
CHANGES IN EGG LIPID COMPOSITION IN RELATION TO CONSECUTIVE
SPAWNS IN Litopenaeus vannamei
F. G. Arcos1, I. S. Racotta1,2, Ana M. Ibarra1 and E. Palacios1,3
1
Centro de Investigaciones Biológicas del Noroeste (CIBNOR), Mar Bermejo 195, Col. Playa Palo de Santa
Rita, La Paz, B.C.S. 23090, Mexico; email of presenting author: epalacio@cibnor.mx
2
Ifremer-Centre de Brest, Département PFOM, UMR100, LPI, Technopole Brest Iroise, 29280 Plouzané
3
UMR/CNRS Université de Bretagne Occidentale; Institut Universitaire Européen de la Mer LEMARLaboratoire des sciences de l'environnement marin (UMR 6539) Technopole Brest Iroise, Place Nicolas
Copernic, 29280 Plouzané - France
It has been previously shown that egg and larval quality of shrimp decreases over time during
larvae production after eyestalk ablation of females. This effect might be a result of decreased
accumulation of biochemical reserves in eggs as a result of physiological exhaustion of
females. However, this negative consequence was apparently not due to individual successive
spawns of the same female. The aims of the present study are to further analyze the
characteristics of physiological exhaustion in terms of lipids composition in eggs. Distinction
between the relative effects of time in production and successive spawns was considered by
obtaining individual spawns from tagged females, that allows spawning order recording, at
different time during a production period of 30 days. Fecundity, fertilization, egg diameter,
and general biochemical composition, including pigments and vitellin content were not
significantly different among successive spawns from the same female (1 to more than 5),
although several of these indicators of spawn quality decreased over time in production. No
differences in lipid classes concentration were observed over successive spawns. The
proportions of 16:0 and 18:1n-7 in phospholipids were higher in eggs from more than 5
spawns. These effects were not corrected when using time in production as a covaribale in an
ANCOVA analysis, indicating that it was a specific effect of successive spawns. For the
proportion of 16:0 and unsaturation index, significantly lower values were obtained for the
eggs of the first spawns, only when using and ANCOVA with time in production as
covariable, indicating that an effect of successive spawns could be masked by the effect of
time in production. These results confirm that egg quality in terms of lipid composition is not
affected by successive spawns.
OUTBREEDING DEPRESSION IN HYBRIDS OF THE MUSSELS MYTILUS EDULIS
AND M. GALLOPROVINCIALIS AT EARLY LARVAL STAGES: EVIDENCE FROM
SINGLE PAIR MATINGS
Frederico M. Batista1, 2, Tom Galley1, Henrique Guedes-Pinto2 and Andy R. Beaumont1
1
School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, Wales LL59 5EY, United Kingdom;
email of presenting author: f.batista@bangor.ac.uk
2
Instituto de Biotecnologia e Bioengenharia, Centro de Genética e Biotecnologia da Universidade de Trás-osMontes e Alto Douro, CGB-UTAD/IBB, P-5000-911 Vila Real, Portugal.
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Poster
Natural hybridization between the mussels Mytilus edulis and M. galloprovincialis occurs to
varying degree in areas where the species distribution overlap. However, the two taxa remain
morphologically, physiologically and genetically distinct in areas of allopatry despite the
prolonged planktonic larval stage that should facilitate dispersal and consequently gene flow.
Indeed, a patchwork of mixed pure and hybrid populations of these mussel taxa have been
observed around European Atlantic coasts. Experimental hybridization can be a valuable tool
to investigate putative pre- and post-zygotic mechanisms involved in the maintenance of
hybrid zones. Individuals of M. edulis (from Menai Strait, Wales, UK) and M.
galloprovincialis (Ria Formosa, Portugal) were spawned in the laboratory. A series of full
reciprocal crosses were carried out between one female and one male of each taxon in order to
enable the comparison of pure and reciprocal hybrid families. Seventy two hours after
fertilization, there were no significant differences among groups in the proportion of eggs
which developed into larvae. However, a significant lower proportion of normal larvae (14.8
%) was observed in the hybrids derived from a M. edulis female and a M. galloprovincialis
male (EG hybrids) in comparison with M. edulis (76.8 %), M. galloprovincialis (75.4 %) and
GE hybrid (75.4 %) progenies. However, this pattern was not observed in all full reciprocal
crosses that were carried out. These findings support the hypothesis that the fitness of hybrid
mussels can be inferior to that of parental taxa at an early larval stage for certain pair matings
between females of M. edulis and males of M. galloprovincialis. The role of disruption of
doubly uniparental inheritance of mitochondrial DNA in the low viability of EG hybrids is
discussed.
DIFFERENCES IN GROWTH RATE AND PROPORTION OF READY TO SETTLE
LARVAE BETWEEN DIPLOID AND TRIPLOID MYTILUS EDULIS
Frederico M. Batista1, 2, Tom Galley1, Helen McCombie3, Florence Cornette3, Pierre
Boudry 3, 4, Henrique Guedes-Pinto2, Jonathan King1 and Andy R. Beaumont1
1
School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, Wales LL59 5EY, United Kingdom;
email of presenting author: f.batista@bangor.ac.uk
2
Instituto de Biotecnologia e Bioengenharia, Centro de Genética e Biotecnologia da Universidade de Trás-osMontes e Alto Douro, CGB-UTAD/IBB, P-5000-911 Vila Real, Portugal.
3
Institut Français pour la Recherche et Exploitation de la Mer (IFREMER), Laboratoire de Génétique et
Pathologie, 17390 La Tremblade, France
4
Present address: Ifremer, UMR M100 Physiologie et Ecophysiologie des Mollusques marins, BP 70, 29280
Plouzané, France
Triploid bivalve molluscs contain three sets of chromosomes in each cell instead of the usual
two sets of chromosomes. Significant physiological differences have been reported between
diploid and triploid bivalves. Triploids have usually poorly developed gonads and grow faster
than diploids. However, differences between diploids and triploids are less accentuated before
maturity. At the larval stage, triploids exhibit similar mortality and growth rates to diploids
although some studies have documented that triploids can grow faster. Ripe Mytilus edulis
were collected from the Menai strait (Wales, UK) and spawned in the laboratory. One female
was mated with three different males in order to produce three half-sib families. Triploidy
induction was carried out by chemical treatment and ploidy level was determined by flow
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Poster
cytometry. High percentages of triploids were observed both at 72 h (96.3-98.2) and 31 days
(98.0-100) after fertilization. Triploid larvae grew slightly larger after 31 days than diploid
larvae in the 3 families. However, a significant lower percentage of ready to settle larvae was
observed in the triploids (10 – 23) in comparison with the diploids (31-39). These results
suggest that triploid larvae will settle and metamorphose later in comparison with diploid
larvae despite their apparently faster growth rate. These findings highlight potential
physiological differences that could exist between diploid and triploids during the larval
phase.
MOLECULAR IDENTIFICATION OF BIVALVE LARVAE FROM THE SOFTSEDIMENT HABITATS IN NORTHERN NEW ZEALAND.
C. Cleguer1, S. D. Lavery2 and M. A. Sewell2
1
Leigh Marine Laboratory, University of Auckland, New Zealand; email of presenting author:
cleguer@hotmail.fr
2
School of biological sciences, University of Auckland, New Zealand.
Marine bivalves represent a major component of the benthic marine fauna with the majority
of species having a planktonic larval phase during their early life history. Assessing the
diversity and the variability in the distribution of bivalve larvae is crucial for understanding
recruitment variation into the benthic habitat. There is a long history of collecting and
describing bivalve larvae; however, because of their similar appearance during larval
development, ecological studies have been hampered by the difficulty of identifying early
stage marine bivalves to the species level. The Whangateau Harbour in New Zealand is of
particular interest due to its high bivalve diversity (14 different species). However, a previous
study at this location failed to morphologically differentiate the larvae to species level. Other
investigations at different locations have used immunological and DNA-based techniques to
identify bivalve larvae, but many difficulties still remain in consistent species identification.
Therefore the present study will focus on developing an effective DNA-based technique for
species identification using direct DNA sequencing of the nuclear gene 18s and the ribosomal
gene COI. This method will also enable a greater ability to assess the spatial and temporal
larval diversity in the Whangateau Harbour and make an important contribution to
understanding the biodiversity and ecology of New Zealand’s bivalve fauna.
ULTRASTRUCTURAL CHANGES IN TRANSPORT TISSUES OF FIRST STAGE
LARVAE OF THE ESTUARINE CRAB NEOHELICE (CHASMAGNATHUS)
GRANULATA AS A CONSEQUENCE OF EMBRYONIC EXPERIENCE
L. Giménez1 and M. Charmantier-Daures2
1
School of Ocean Sciences, Bangor University, LL59 5AB Menai Bridge, Wales, United Kingdom; email of
presenting author: l.gimenez@bangor.ac.uk
2
Equipe Adaptation Ecophysiologique et Ontogenèse UMR 5119: ECOLAG, Université Montpellier II, cc 092,
Place E. Bataillon, 34095 Montpellier cedex 05, France
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Poster
Environmental conditions experienced by embryos can affect larval performance through
carry-over and latent effects. For instance, embryos and first stage larvae (Zoea I) of the
estuarine crab Neohelice granulata experience low and variable salinity under natural
conditions. The survival of Zoea I larvae at low salinity (5-10) is considerably increased if
embryos experience moderately low salinities (15-20) as compared with embryos exposed to
sea water (salinity: 32). High larval survival at low salinity is maintained by a stronger
osmoregulatory capacity developed as a consequence of embryos being exposed to low
salinity. Increased osmoregulation should be achieved through biochemical and structural
responses occurring in the larval transport tissues. Here, we investigated if the salinity
experienced during embryogenesis affected the structure of the epithelial cells of the transport
tissues of Zoea-I larvae. Transmission electronic microscopy revealed numerous apical
microvilli in the epithelial cells of transport tissues from zoea-I hatched from embryos
exposed to salinities of 15 and 20. By contrast, these structures were not present in larvae
hatched from embryos exposed to 32. We interpret these changes as an adaptive response to
low salinity conditions: increments in microvilli should increase surface area and Na+ uptake
at low salinity.
WHY DOES NORWAY LOBSTER USES MULTIPLE PATERNITY?
Sara Mira1, Antonina dos Santos2, M. Leonor Cancela1 and Margarida Castro1
1
CCMAR, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; email of presenting
author: smira@ualg.pt
2
IPIMAR- Instituto Nacional de Recursos Biológicos, Av. Brasília, s/n, 1449-006 Lisboa, Portugal
Norway lobster (Nephrops norvegicus) is a valuable resource that is currently overexploited,
resulting in a reduction in number of individuals. This may lead to a decrease in genetic
variability increasing the genetic load and putting at risk the evolutionary capacity for
adaptation. Since fishing-induced mortality in this species is higher in males than in females,
a reduction in population size can also result in a biased sex ratio. A hypothesis to overcome
this problem is that populations may change their mating strategies to a multiple paternity
approach and therefore increase the genetic diversity and the effective population size. Here
we propose to analyse and compare two populations: one with low exploitation rates (trap
fishing in areas inaccessible to trawling) and another subjected to high exploitation rates
(trawl fishing grounds). The different exploitation rates are confirmed by the size structure
and sex ratios (low exploitation associated with larger sized individuals and a balanced sex
ratio). We used six specific microsatellite markers for paternity analyses. The females and
their eggs were genotyped and the putative number of fathers for each clutch was estimated
by direct counting of the number of alleles. Results reveal high levels of multiple paternity in
the less exploited population and absence on the highly exploited population with unbalanced
sex ratio which is in contrast with our expectations. We will discuss our results taking into
consideration each population characteristics, and new hypothesis will be presented to explain
our findings. This work was funded by LobAssess Project (POCI/BIA-BDE/59426/2004) and
S Mira is the recipient of a postdoctoral fellowship (SFRH/BPD/23514/2005), both from the
Portuguese Science and Technology Foundation.
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Poster
LIPID AND FATTY ACID COMPOSITION DURING EMBRYOGENESIS AND
EARLY LARVAL DEVELOPMENT IN SHRIMP (Litopenaeus vannamei)
E. Palacios1,2 and I. S. Racotta1,3
1
Centro de Investigaciones Biológicas del Noroeste (CIBNOR), Mar Bermejo 195, Col. Playa Palo de Santa
Rita, La Paz, B.C.S. 23090, Mexico; email of presenting author: epalacio@cibnor.mx
2
UMR/CNRS Université de Bretagne Occidentale; Institut Universitaire Européen de la Mer LEMARLaboratoire des sciences de l'environnement marin (UMR 6539) Technopole Brest Iroise, Place Nicolas
Copernic, 29280 Plouzané - France
3
Ifremer-Centre de Brest, Département PFOM, UMR100, LPI, Technopole Brest Iroise, 29280 Plouzané
We analyzed the changes in lipid classes and fatty acid composition of reserve and structural
lipids that occur from recently spawned eggs till zoea I stage. Spawns from eight females
sampled under the same conditions were individually reared to zoea stage at 28°C, 36‰, and
100 nauplii L-1. Fertilization rate (68%) was estimated from three subsamples from each
spawn taken 12 h after spawning, and were not significantly different among spawns. Tanks
were sampled periodically after spawning; at 1 hour (eggs in the first and second cellular
cleavage, average diameter, 254±3µm), 13h (nauplii stage I, average length, 297±4µm), 33h
(nauplii III, 365±6µm), 57h (nauplii IV, 448±5µm), and 79h (zoea stage I, 493±6µm).
Triacylglycerides (TG) decreased from 58% of total lipids in recently spawned eggs to less
than 10% in zoea I, while phospholipids (PL) increased from 37% in eggs to more than 80%
in zoea I. Free cholesterol decreased while esterified cholesterol increased during
development. The proportion of saturated fatty acids increased while polyunsaturated fatty
acids (PUFA) decreased in reserves. An increase of the relation 22:6n-3/20:5n-3 in reserves
during the development was found, a result of a decrease of 20:5n-3 from 18% in eggs to 9%
in zoea, and of 22:6n-3 from 22% in eggs to 18% in zoea, but the proportion of 20:4n-6 in
reserves during development remained constant. The proportion of saturated and
monounsaturated fatty acids in PL decreased, while the proportion of PUFA increased, but the
relation 22:6n-3/20:5n-3 remained constant. The differences between fatty acid concentration
s in zoea and eggs revealed that saturated fatty acids accumulated during development in
phosphatidylethanolamine and phosphatidylserine, while the rest of the fatty acids decreased
in concentration. These results are in accordance to a higher conservation of PUFA in PL,
possibly as a result of transference from TG during lecithotrophic development.
LEUCYL AMINOPEPTIDASE ACTIVITY IN Octopus vulgaris (CUVIER, 1797)
(MOLLUSCA, CEPHALOPODA) PARALARVAE
I. Pozuelo, M. A. Bruzón
1
IFAPA Centro El Toruño. Camino Tiro Pichón s/n. 11500. El Puerto de Santa María (Cádiz). Spain; email of
presenting author: ignacio.pozuelo.ext@juntadeandalucia.es
The common octopus Octopus vulgaris (Cuvier, 1797) paralarvae are carnivorous (Villanueva
et al., 2001), have a predominance of amino acid metabolism (O’Dor and Wells, 1987; Lee,
8th Larval Biology Symposium
Lisbon, 2008
Genetics and physiology
Poster
1994), and exhibit ontogenetic shift in diet towards higher prey sizes (Mangold, 1983).
Hatchlings have a well developed digestive tube, although full functionality is not clear.
Newborn paralarvae have both an outer and an inner yolk sac filled with nutritive reserves,
which are consumed parallel to exogenous feeding (Boletzky, 1989).
The study of O. vulgaris digestive enzymes has become a common tool for nutritive
requirement assessment in this species. A histochemical approach to digestive enzyme
activities may provide useful information on important questions such as the dependence of
paralarvae upon nutritive reserves and exogenous enzyme sources, and ontogenetic shift in
diet.
Since protein digestibility and assimilation are high in octopus’s paralarvae (Lee, 1994);
proteases can be used as spawn/offspring quality index (Morote et al., 2005). Leucyl
aminopeptidase is a cytosol protease implicated in intracellular processes of protein digestion,
and has been used for the study of proteases in different organisms.
Leucyl aminopeptidase activity assay (Nachlas et al., 1957) was performed in O. vulgaris
paralarvae. Enzyme activity was measured in three types of paralarvae: paralarvae aged 0
days, starving paralarvae aged 3 days, paralarvae aged 3 days fed with Artemia salina (L.,
1758). Leucyl aminopeptidase activity was assessed according to the following activity scale:
(-) absence; (+) moderate; (++) high; (+++) very high.
Leucyl aminopeptidase activity was recorded in all three types of paralarvae. High activity
levels were recorded in liver and caecum, and moderate activity in stomach and pancreas.
Posterior salivary glands showed moderate activity in 0-days-old and 3-days-old paralarvae
fed with A. salina. This shows an initial stage of protein digestion and absorption occurring
inside these organs cells, normal course of paralarvae digestion.
8th Larval Biology Symposium
Lisbon, 2008
Morphology, larval development and growth
Oral
SYNERGISTIC
EFFECTS
OF
NERVE
GROWTH
FACTOR
ELECTROMAGNETIC FIELDS ON NEURAL STRUCTURES OF
FRESHWATER SHRIMP ATYAEPHYRA DESMARESTII LARVAE
AND
THE
Chryssa Anastasiadou1, Ioannis I. Verginadis2, Spyridon Ch. Karkabounas2, Ioannis D.
Leonardos1, Angelos M. Evangelou2 and Vassiliki P. Kalfakakou2
1
Laboratory of Zoology, Department of Biological Applications and Technology, University of Ioannina,
University Campus, 45110, Ioannina, Greece; email of presenting author: me01247@cc.uoi.gr
2
Laboratory of Physiology, Unit of Environmental Physiology, Faculty of Medicine, University of Ioannina,
University Campus, 45110, Ioannina, Greece.
Nerve Growth Factor (NGF) is a member of the neurotrophin family of polypeptide growth
factors, which stimulates the growth and the differentiation of embryonic neurons.
Developmental pathways may be affected by various factors or their electromagnetic emission
prints. NGF electromagnetic field (EMF) specific radiofrequency (RF) is generated and
emitted through an electromagnetic pulse generator (MCDE). The purpose of the present
study is to investigate the effects of NGF on neural structures of the first zoeal stage
anameric development of the freshwater shrimp Atyaephyra desmarestii as well as the action
of low intensity NGF –EMF RFs. Ovigerous specimen collected from Louros River (NW
Greece) were reared in the laboratory. The hatched larvae were transferred into tanks with
dechlorinized water and pumped air supply before the NGF-EMFs exposure, in order to
obtain stable stock conditions. Three groups of animals were exposed to the following
conditions: Group A larvae were divided in 4 subgroups and incubated in 1, 3.6, 20, and 40
ngr/ml of NGF correspondingly. Group B larvae were subjected to the emission of the
characteristic for NGF-EMF RF spectrum. Group C larvae were exposed both at low NGF
concentrations (1, 0.4, 0.2 ngr και 100 pgr/ml) and the characteristic for NGF, EMF RF
spectrum. Two groups of larvae, in DMEM and habitat water, were used as controls. NGF
incubation lasted 30 min. The duration of EMFs emission was 45 min. Larvae from each
group were photographed and preserved in 4% formalin solution. The % increase of exposed
larvae neural structures was compared to the control groups by means of a plan meter. All
experimental groups (A,B and C) revealed larval neural structure increase compared to
control groups whereas Group C presented statistically significant increase probably due to
synergistic NGF and NGF-EMF spectrum effect.
COMPARISON OF LARVAL DEVELOPMENT OF SIX SPECIES OF HERMIT
CRABS FROM THE EAST PACIFIC
M. Ayón-Parente1 and M. E. Hendrickx2
1,2
Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de
Mexico, P.O. Box 811, Mazatlán, Sinaloa 82000, Mexico; email of presenting author:
michel@ola.icmyl.unam.mx
Specimens of six species of hermit crabs (Calcinus californiensis, Clibanarius sp. nov.,
Paguristes anahuacus, Stratiotes sp. nov., Phimochirus roseus, and Pagurus sp. nov.) were
collected between March and August 2007 in distincts natural habitats in the Gulf of
Lisbon, 2008
8th Larval Biology Symposium
Morphology, larval development and growth
Oral
California, Mexico. Specimens of each species were kept in separate aquarium (mostly males
and females, but also ovigerous females) in marine water (35 ppm; 22-23 oC). All species
produced eggs and larvae were succesfully obtained and reared to at least the first megalopa.
Number of zoeae and periods between each stage varied considerably among species:
Calcinus californiensis, 6 zoeae, with intermolt period of 7-9, 5-7, 6-8, 3-6, 4-6 and 6-8 (to
megalopa) days. Clibanarius sp. nov., 4 zoeae, with intermolt period of 7-10, 4-9, 6-12 and 518 (to megalopa) days; Paguristes anahuacus, 2 zoea, with intermolt period of 1 and 1 (to
megaopa) day; Stratiotes sp. nov., 3 zoeae, with intermolt period of 4, 2 and 2 (to megalopa)
days; Phimochirus roseus, 5 zoeae, with intermolt period of 4-10, 9-12, 3-8, 3-6, and 2-4 (to
megalopa) days; and Pagurus sp. nov., 4 zoeae, with intermolt period of 5-6, 4-7, 4-8, and 3-9
(to megalopa) days. Short-lived megalopa lasted 3-4 (P. anahuacus) to 8 (Stratiotes sp. nov.)
days. The rest survived between 10 and > 30 days. Preliminary examination of larval
morphology indicates significant variation in characters among the six genera.
ONTOGENY OF UPPER
(PENTASTOMIDA)
CAMBRIAN
PARASITIC
TONGUE
WORMS
Christopher Castellani, Joachim T. Haug, Andreas Maas and Dieter Waloszek
Work Group Biosystematic Documentation, University of Ulm, Helmholtzstrasse 20, D-89081 Ulm, Germany;
email of presenting author: christopher.castellani@uni-ulm.de
No one would disagree that there is only one evolution and one phylogeny. Yet, the dissent
between morphological-data based and molecular-data based reconstruction of the systematic
affinities of animal is often striking. The systematic position of the parasitic tongue worms,
nowadays a species-poor, enigmatic arthropod group of worm-shaped parasites of the
respiratory tract of many land-living tetrapod taxa, is one of such examples. The positional
difference between an assumed close alliance to certain in-group eucrustaceans, the fish lice,
and a derivation from even before the Arthropoda s. str. could not be larger. The latter
hypothesis was supported by the discovery of pentastomids, including isolated early
ontogenetic stages, from marine Cambrian deposits (500 Million years old). In 2004, new
material of more than 60 specimens of fossil representatives could be extracted from
limestone collected in Västergötland, Sweden. Their study, using several methods such as
SEM, biometry and cluster analysis, demonstrates the presence of different successive
ontogenetic stages most likely belonging to different species. Our principal aim is to describe,
for the first time, the ontogeny of early pentastomids – at least three successive stages – in
detail, and the morphogenesis of all major external structures. We also are aiming to analyse
and discriminate the different species from the new material, which shall lead to a reevaluation of the taxonomic status of all hitherto described Cambrian pentastomids. Lastly,
we expect to contribute further to the ongoing controversy about the systematic position of
this group of parasites.
8th Larval Biology Symposium
Lisbon, 2008
Morphology, larval development and growth
Oral
CAN WE PREDICT CORIS JULIS RECRUITMENT SUCCESS FROM LARVAL
GROWTH, SIZE AND STAGE DURATION?
J Fontes1, R S Santos1, P Afonso1 and J E Caselle2
1 - IMAR / Department of Oceanography and Fisheries, University of the Azores, PT: 9901-862 Horta,
Portugal; email of presenting author: fontes@uac.pt
2- Marine Science Institute, University of California Santa Barbara, CA 93106
We analyzed patterns of recruitment and early life history of a reef fish, Coris julis from four
islands and one offshore islet, in the Azores archipelago to test relevance of early life history
to recruitment success over two consecutive seasons. Growth from hatch to age was a better
predictor of recruitment then was growth averaged over the entire pelagic stage. This implied
that, early growth appears to be more relevant to larval survival and recruitment than later
growth, and that larger-at-age larvae have a survival advantage and contribute more to high
recruitment, supporting the “bigger-is-better” hypothesis. In 2005 we found evidence that
supports the “stage duration” hypothesis, although, between-site larval stage duration
variability in 2004 was too low to allow any conclusions to be drawn. Our predictions about
the relationships between size at age (SAA), size at settlement (SAS) and recruitment were
also generally supported. In 2004, SAA was positively correlated with SAS and with
recruitment, although the latter relationship was not significant. In 2005, SAA and SAS were
not correlated wile SAS was negatively correlated to recruitment. We discuss these
relationships on the basis of compensatory and synergistic effects of larval growth, size and
stage duration on larval survival and recruitment. These results highlight the relevance of
understanding the factors that determine recruitment and larval-survivorship patterns, as this
may provide a basis for prediction of recruitment and thus management of resources.
500 MILLION YEARS OLD CRUSTACEAN LARVAE FROM THE ‘ORSTEN’
Joachim T. Haug, Dieter Waloszek and Andreas Maas
Work Group Biosystematic Documentation, University of Ulm, Helmholtzstrasse 20, D-89081 Ulm, Germany;
email of presenting author: joachim.haug@uni-ulm.de
The fossil record of undisputed crustacean larvae is scarce. A famous early example is
†Lepidocaris rhyniensis Scourfield, 1926 from the Devonian Rhynie Chert, Scotland, a
branchiopod that is known besides sexually dimorph adults also from larval stages. Less wellknown examples are the phyllosoma larvae of three species of palinurid malacostracans from
the Upper Jurassic, Solnhofen, Germany and a single fragment of a crab zoea from the
Cretaceous of Brazil. All these examples are outranged by the fossil larvae from the lower
Cambrian to Cretaceous in an ‘Orsten’ type of 3D preservation of small, mainly arthropod
animals in phosphate. This special kind of fossil preservation has been discovered in many
locations all over the world, for example Australia, China, Europe, North America and
Siberia, and ranges, in its widest sense, even from the Precambrian (3D embryos) up to the
Tertiary (insects). In a more restricted sense, ‘Orsten’ fossils, mainly arthropods, have a
8th Larval Biology Symposium
Lisbon, 2008
Morphology, larval development and growth
Oral
surface (cuticle) that has been replaced by calcium phosphate resulting in an extremely fine,
diagenetically uncompressed bodily preservation. Preserved details may be very delicate and
range down to structures as small as 0.2 µm in diameter, such as fine hairs or pores. Preserved
are also appendages, weakly sclerotised membranes, or eye structures. ‘Orsten’ type
preservation has one limitation, size. Neither complete nor fragmentary specimens exceed 2
mm in length; best-preserved specimens are usually around 100–200 µm. This size limitation
leads, on the other hand, to the presence in the material of a large number of larval specimens.
Until now, more than a dozen species has become known with a preserved ontogenetic
sequence. Other species are known exclusively from early larval specimens. The ‘Orsten’ is,
therefore, an invaluable source of especially Palaeozoic larvae with a strong bearing on the
understanding of the evolution of larvae within Arthropoda.
EGG AND LARVAL DEVELOPMENT OF THE VENT GASTROPOD OENOPOTA
OGASAWARANA
Hiromi Watanabe1, Toshishige Itoh2, Suguru Nemoto2 and Katsunori Fujikura1
1
Marine Biology and Ecology Research Program, Japan Agency for Marine-Earth Science and Technology, 215, Natsushima, Yokosuka 237-0061, JAPAN; email of presenting author: hwatanabe@jamstec.go.jp
2
Enoshima Aquarium, 2-19-1 Katase-kaigan, Fujisawa 251-0035, JAPAN
Oenopota whelks are distributed over a wide depth range, from the intertidal zone to 4000m
depth, including around hydrothermal vents and methane seeps. Most vent animals are
endemic to vent environments and it is difficult to compare their ecology with related species
in other environments. Oenopota whelks are an exception. In the present study, we tried to
characterize the vent species Oenopota ogasawarana by observation of its development and
rearing experiments. O. ogasawarana were collected from a hydrothermal vent field on the
Daikoku Seamount, Northern Mariana Arc, at a depth of 399m. After collection, O.
ogasawarana were kept at the Enoshima Aquarium and continued to lay egg capsules in the
aquarium for more than two years. The egg capsule observations revealed that O.
ogasawarana lays a larger number of smaller embryos in a single egg capsule than in other
cold-water Oenopota species, probably due to the instability of vent environments. The
rearing experiments on embryos and larvae showed that temperatures lower than 15ºC are
suitable for laboratory rearing and the intra-capsule development differed according to rearing
conditions. The reared larvae could not metamorphose to juveniles under the present
conditions. The present results show that it is possible to observe egg and larval development
of vent gastropods under laboratory conditions without special equipment and in doing so,
reveal aspects of their ecology.
8th Larval Biology Symposium
Lisbon, 2008
Morphology, larval development and growth
Poster
LARVAL DEVELOPMENT OF THE FRESHWATER SHRIMP ATYAEPHYRA
DESMARESTII (MILLET, 1831) S.L. (DECAPODA: CARIDEA: ATYIDAE) FROM
LOUROS RIVER (NW GREECE) DESCRIBED FROM LABORATORY REARED
MATERIAL
Chryssa Anastasiadou and Ioannis D. Leonardos
Laboratory of Zoology, Department of Biological Applications and Technology, University of Ioannina,
University Campus, 45110, Ioannina, Greece; email of presenting author: me01247@cc.uoi.gr
The complete series of larval staging of Atyaephyra desmarestii (Millet, 1831) s.l. from
Louros River (north-western Greece) was obtained in the laboratory and described in detail.
Several berried females were collected and transferred to aquaria with habitat water and
vegetation. After each hatching, the total number of the larvae per ovigerous female was
estimated by applying the volumetric method. The newly hatched larvae were transferred into
small sterile aquaria and mass cultured. The larvae were maintained at ambient temperature
23-25 oC and fed through development with detritus and newly hatched Artemia nauplii. After
each moult, several larvae were photographed and preserved with their excuviae. The time
period between each moult and the subsequent was recorded for determining the duration of
each stage. The reared larvae of Atyaephyra desmarestii passed through six zoeal stages, one
megalopal stage and the first juvenile stage. At the experimental conditions, the average
durations of the larval stages were as follows: three days for 1st stage, four days for 2nd stage,
six days for 3rd stage, seven days for 4th stage, nine days for 5th stage, nine days for 6th stage
and nine days for the megalopal stage. These stages were described in detail. Comparison of
the larval morphological characters among the described material, the larvae specimens
collected from natural populations and the bibliographic data of closely related species was
made and discussed.
FINE STRUCTURE OF THE LECITHOTROPHIC BRACHIOLARIA LARVAE IN
TWO SPINULOSID SEA STARS
Philippe Bailly and Patrick Flammang
Laboratoire de Biologie Marine, Université de Mons Hainaut, 6 av du Champs de Mars, B-7000 Mons, Belgium;
email of presenting author: philippe.bailly@umh.ac.be
Most asteroid species present an indirect development with a pelagic larval phase, either
planktotrophic or lecithitrophic, and a benthic adult phase. Transition between the two phases
takes place at the brachiolaria stage and involves the brachiolaria attachment complex which
allows substratum testing and temporary attachment during settlement, and permanent
fixation during metamorphosis. Very little is known about the development, fine structure and
functioning of the attachment complex in asteroids with non-feeding larvae. We described the
ultrastructure of the brachiolaria larvae in two common European spinulosid sea stars with
lecitotrophic developments, Echinaster sepositus from the Mediterranean Sea and Henricia
Lisbon, 2008
8th Larval Biology Symposium
Morphology, larval development and growth
Poster
oculata from the Atlantic Ocean. The brachiolaria stage extends from day 3 to 8 after
fertilization for E. sepositus (at 20°C) and from day 12 to 25 for H. oculata (at 15°C).
Competent braciolariae are large (up to 3 mm) and uniformly ciliated. They consist of a
posterior spheroidal body and a very large attachment complex made up of three brachiolar
arms (one long anterior arm and two short posterior arms) surrounding a central adhesive disc.
The arms do not bear the sensory-secretory papillae characteristic of planktotrophic
brachiolariae, but enclose sensory cells and a duo-gland system consisting of adhesive (type
A) and de-adhesive (type B) secretory cells. Type A cells are ciliated and contain large
heterogeneous secretory granules. The ultrastructure of these granules is more complex in H.
oculata than in E. sepositus. Each adhesive cell is closely associated to one support cell
containing a bundle of filament connecting its basal and apical parts. Type B cells contain
numerous small electron-dense secretory granules. In the adhesive disc, typical type D
secretory cells can be recognized, containing the permanent adhesive secretion used for
fixation. Their granules are homogeneous and electron-dense in E. sepositus and less dense
with two dark poles in H. oculata.
A BRIEF COMMUNICATION
CHAULIODUS SLOANI EMBRYO
–
ABNORMAL
DEVELOPMENT
OF
A
L. Correia and A. Amorim
Direcção de Serviços de Investigação das Pescas – DSIP- Madeira, Portugal; email of presenting author:
lina.correia@gmail.com
In spite of the wide bibliography on ichthyoplankton and the studies done on this subject,
many works is yet to be done concerning mainly the embryonic and pre-larval stages.
However none of these works consulted mention the existence of an egg from this specie,
Chauliodus sloani Bloch and Schneider, containing more than one embryo. The purpose of
the present communication is precisely to describe such abnormal development, apparently
not registered until now, and the location and some characteristics of the place where this
specimen was collected.
MORPHOLOGY OF THE LARVAL STAGES OF GEOGRAPSUS LIVIDUS
(CRUSTACEA, DECAPODA, BRACHYURA) REARED UNDER LABORATORY
CONDITIONS, WITH THE DESCRIPTION OF NEW LARVAL CHARACTERS FOR
THE GRAPSIDAE
J. A. Cuesta1, G. Guerao2, C. D. Schubart3 and K. Anger4
1
ICMAN, CSIC. Avenida República Saharaui, 2, 11519 Puerto Real, Cádiz, Spain; email of presenting author:
jose.cuesta@icman.csic.es
2
IRTA, Unitat de Cultius Experimentals, Carretera Poble Nou, km 5.5, 43540 Sant Carles de la Ràpita, Spain
3
Biologie I, Universität Regensburg, D-93040 Regensburg, Germany
4
Biologische Anstalt Helgoland, Alfred-Wegener-Institut für Polar- und Meeresforschung, Meeresstation, 27498
Helgoland, Germany
8th Larval Biology Symposium
Lisbon, 2008
Morphology, larval development and growth
Poster
Among the eight currently recognized genera and approximately 40 species belonging to the
brachyuran crab family Grapsidae, the complete larval development has only been known for
three species of Metopograpsus. In the present study, we investigated the larval development
of Geograpsus lividus originating from Jamaica and reared under controlled conditions in the
laboratory. It consists of 8 zoeal stages and the megalopa, representing the longest recorded
developmental pathway for any brachyuran. Although longer developments with more than
10 zoeal stages had been suggested for some species, based on specimens collected from the
plankton, these were never confirmed by laboratory culture. In the present communication,
the morphological and meristic characters of the larval stages of G. lividus are described and
illustrated. The larvae share most characters established for the family Grapsidae. The two last
zoeal stages, however, show some new features, which do not correspond with the typical
setation pattern known from grapsid species with only 5 zoeal stages. These were found in the
number of natatory setae on the exopods of the maxillipeds, and in the setation of the basis of
the first maxilliped. Other characters, which had previously only been described for zoeae of
Pachygrapsus and Planes, were observed also in G. lividus and could be common features for
the Grapsidae. Moreover, the larvae of G. lividus present a spinulation on the lateral and
rostral spines of the cephalotorax. This character is recorded for the first time in grapsid crabs.
A comparison of these observations is made with those based on late zoeal stages of species
belonging to closely related families, where similar characters have been documented.
EMBRYONIC AND LARVAL DEVELOPMENT STAGES OF MEAGRE Argyrosomus
regius UNDER REARING CONDITIONS
K. Gamsiz1 and M. Neke2
1
Ege University, Fisheries Faculty, Aquaculture Department, Bornova, 35100, Izmir, Turkey; email of
presenting author: kutsal.gamsiz@ege.edu.tr
2
Egemar Su Urunleri AS. Akbuk, Aydin, Turkey
Argyrosomus regius (also known as Meagre) is a fish of the Sciaenidae family. The meagre is
found in the Mediterranean and Black Sea and along the Atlantic coasts of Europe and the
west coast of Africa. The meagre has been considered a very promising candidate species for
the Mediterranean aquaculture. The cultural advantages of this meagre came from its; fast
growing rate, adaptation in wide range of salinity, high FCR and also high nutrient content.
With these advantages this specie became alternative aquaculture specie instead of sea bass
and gilthead sea bream. However, studies about its early life history and rearing conditions
are limited on embryonic and larval development of the specie under captivity. This study was
carried out to evaluate embryonic and larval development stages of meagre under rearing
conditions. The experiment were maintained at 22±0,5º C. Eggs were obtained from wild
broodstock using hormonal treatment (LhRH). The average diameters of the eggs and oil
globule were measured 857±23µ and 215±10 µ, respectively. Embryonic development stages
were observed in every 10 minutes and photographs were taken each time when some
significant change had occurred at embryonic development stages. At 22±0,5ºC, the eggs
8th Larval Biology Symposium
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Morphology, larval development and growth
Poster
hatched 24 hours after fertilization. The mean body length of larvae was measured 25934 ± 55
µ after hatching. Larval development had been observed for 30 days after hatching.
ALLOMETRIC GROWTH PATTERNS OF BAY SNOOK PETENIA SPLENDIDA
DURING EARLY ONTOGENY
E. Gisbert1, C. A. Alvarez-González2, L. Treviño1, N. Perales-García2, L. Arévalo-Galán2
and A. Uscanga-Martínez2
1
IRTA – Sant Carles de la Ràpita, Crta. Poble Nou km 5.5, 43540 Sant Carles de la Rapita, (Tarragona), Spain;
email of presenting author: enrich.gisbert@irta.es
2
DACBIOL Lab. Acuacultura, Universidad Juárez Autónoma de Tabasco, Crta. Villahermosa–Cárdenas km.
0.5, Villahermosa, Tabasco 86039, Mexico
The Petenia splendida is a demersal freshwater neotropical fish that belongs to the Cichlidae
family (subfamily: Cichlasomatinae) and inhabits lakes and lower river valleys in Central
America (Mexico, Guatemala and Belize). Among cichlids, the largest knowledge is on the
African species, but little is known on the Mexican cichlids and their early development. We
studied the morphological development and allometric growth patterns of bay snook larvae
from hatching to the juvenile stage in order to better understand their priorities during early
growth, size related adaptations and provide insight into fish biology, behaviour and ecology.
Bay snook embryos were obtained from two spawnings from a broodstock kept in captivity at
the DACBIOL facilities. After hatching (3 days post fertilization, dpf) yolk-sac larvae were
placed into a 1000 l tank (0.75 larvae l-1) connected to an open water system (29ºC, 6.5 mg O2
l-1, pH 7.4). Larvae were feed to satiation four times per day with Artemia nauplii from the
mouth opening at 6 dpf (3 days post hatching, dph) until 15 dph. Afterward, larvae were fed
three times per day with a dry trout diet (Silver Cup, Nelson & Sons, Inc.) until day 60 dph.
Every two days, twenty fish were sampled, sacrificed, and from each specimen seven
morphometric characteristics associated with swimming abilities, vision and feeding were
measured to the nearest 0.01 mm using a binocular microscope with AnalySIS software (Soft
Imaging Systems). These characteristics were: (1) standard length - LS; (2) tail length; (3) tail
height; (4) trunk length; (5) head length; (6) head height; and (7) eye diameter. Allometric
growth was calculated as a power function of LS using non-transformed data: y=a LSb; where
y was the measured character, a the intercept, and b the growth coefficient.
Results showed that morphogenesis and differentiation were more intense during the larval
and early juvenile stages; the larval period was characterized by the replacement of embryonic
adaptations and functions by definitive ones, such as branchial respiration, exogenous
feeding, and active swimming.
SKELETAL DEFORMITIES IN SENEGAL SOLE (SOLEA SENEGALENSIS) UNDER
INTENSIVE REARING CONDITIONS
E. Gisbert, M. S. Pimentel and I. Fernández
8th Larval Biology Symposium
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Morphology, larval development and growth
Poster
IRTA – Sant Carles de la Ràpita, Crta. Poble Nou km 5.5, 43540 Sant Carles de la Rapita, (Tarragona), Spain;
email of presenting author: enrich.gisbert@irta.es
Generally, marine fish larvae hatch much earlier in their development than other vertebrates,
suggesting that the spatiotemporal sequences of the skeletal development in teleosts are
different from those of higher vertebrates. In Senegal sole larvae, these developmental
processes still continue after hatching, which facilitates studies on skeletogenesis. Skeletal
deformities downgrade biological performance, swimming and feeding capabilities, and
survival of affected larvae. The development of skeletal disorders is linked to a poorly
understood relationship between nutrition, environment and genetic factors. Thus, we
examined the incidence of skeletal deformities in juveniles of Solea senegalensis reared under
intensive rearing conditions in order to analyse quantitatively the typology of different
skeletal anomalies.
Larvae were reared in a recirculation water system at 18-19ºC, 35 ppt salinity, pH 7.8-8.2,
20% daily water exchange and with gently aeration and oxygenation (>4 mg l-1). Photoperiod
was 12L:12D. Larvae were fed from 3 to 10 dph with increasing densities of enriched rotifers
(Brachionus plicatilis; 20-5 rotifers ml-1). Artemia metanauplii were offered to larvae from 6
to 37 dph (0.5-12 metanauplii ml-1). From 33 dph to the end of the experiment (50 dph),
larvae were progressively weaned onto dry feed (Gemma Micro 300©; Skretting). Fish
(n=150) were stained for bone (alizarin red) and cartilage (alcian blue) on whole mounts using
the double staining method.
The vertebral column and caudal fin complex were the regions of the skeleton mostly affected
by skeletal disorders, while no anomalies were detected in the cranium. According to the
vertebral column, most of the deformities were observed in the haemal and prehaemal
regions, although those from the haemal region were more severe than the others. The main
skeletal disorders in the vertebral column were: fusion and compression of vertebral centrums,
deformed vertebral centrums, twisted neural and haemal spines, and deformed parapophysis.
Regarding the caudal fin, deformities mostly affected the epural, hypurals, parahypurals,
modified neural and haemal spines. The incidence and typology of these deformities are
discussed according to the morphogenesis of this flatfish species.
MORPHOLOGICAL PLASTICITY IN DENDRASTER EXCENTRICUS LARVAE IN
RESPONSE TO FOOD LEVELS AND REALIZED OR PERCEIVED COMPETITION
Suzanne Kacenas
College of Charleston, Grice Marine Biological Laboratory, 205 Fort Johnson Road Charleston, SC 29412; email
of presenting author: sklunsfo@edisto.cofc.edu
Plasticity in morphological, physiological, or behavioral responses permits an organism to
react to temporal or spatial environmental patchiness, and may thereby increase its probability
of survival. Plasticity in marine invertebrate larvae in response to variability in food level or
the presence of predators has been well documented, however, little is known regarding larval
plasticity in response to the presence of competitors. This study focused on the effect of food
level and competitor type on the morphology of the pluteus larvae of a sand dollar,
Dendraster excentricus (Eschscholtz). Plutei were reared at high or low food rations, as well
8th Larval Biology Symposium
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Morphology, larval development and growth
Poster
as in the presence of either feeding or non-feeding heterospecific larvae or nearly natural
plankton populations. Plutei cultured in low food conditions grew substantially longer
postoral rods relative to their body size than plutei cultured in high food conditions, while
those cultured in high food conditions had longer stomach lengths relative to their body size.
The pattern of increase in postoral rod length in response to food scarcity is consistent with
plasticity of investment in ciliary band length. The pattern of increase in stomach length
relative to body size in response to high food conditions is consistent with the shifting of
energy investment into the development of postlarval structures. The presence of competitors,
regardless of whether they were actual (feeding) or perceived (non-feeding), elicited identical
responses in D. excentricus plutei: longer postoral rods and stomach lengths relative to body
size. This result suggests that D. excentricus plutei are responding nonspecifically to the
presence of both actual and perceived competitors by investing in growth of both larval and
postlarval structures.
OTOLITH GROWTH AND MICROCHEMISTRY PATTERNS IN LABORATORY –
REARED ATLANTIC COD (Gadus morhua L.) JUVENILES IN RESPONSE TO
AMBIENT TEMPERATURE AND FISH SIZE
Rommel H. Maneja, Arild Folkvord and Audrey Geffen
University of the Philippines, Philippines; email of presenting author: rhmaneja@yahoo.com
Otolith growth and microchemistry patterns are hypothesized to reflect the early life history of
fishes and could help extract the corresponding environmental conditions experienced by
individual fish. In the study, juveniles of Atlantic cod Gadus morhua L. were reared in the
laboratory for three months until 176 days post hatch (dph) under different water temperatures
and fish sizes to examine the effects on otolith growth and microchemistry. Results showed
that water temperature and fish size significantly affected the daily otolith increment (DOI) in
both dorsal and distal otolith sides. The DOI from the 10-16oC temperature profile was
significantly higher than the 10-10oC and 10-4oC while the 10-10oC was significantly higher
than the 10-4oC temperature profile. Variations in fish size resulted in higher DOI in fishes
with sizes closer to the size of maximum otolith growth, i.e. between 87-116 dph. This
suggested presence of ontogenetic effect in otolith growth. The highest mean DOI (10.7 + 1.3
µm·day-1 dorsal; 7.4 + 1.9 µm·day-1 distal) was obtained from the 10-16oC between 87-116
dph while the lowest mean DOI (3.4 + 0.5 µm·day-1 dorsal; 1.9 + 0.5 µm·day-1 distal) was
obtained from the 4-4oC between 146-176 dph. Otolith elemental concentration of Ca, Sr, and
Na and ratios of Sr:Ca and Na:Ca were measured and intended to corroborate and strengthen
the patterns emerging from the otolith growth analysis. However, instrument and analytical
sensitivity problems yielded non-conclusive results regarding the effects of water temperature
and fish size on otolith microchemistry. This study showed that otolith growth pattern has the
potential to reflect ambient temperature history of juvenile fish during the settling stage and
could be used to elucidate the fish early life history.
8th Larval Biology Symposium
Lisbon, 2008
Morphology, larval development and growth
Poster
MORPHOLOGY OF THE FIRST ZOEAL STAGES OF THE FIVE SPECIES
OF THE GENUS CALLINECTES (CRUSTACEA, DECAPODA, BRACHYURA)
REARED UNDER LABORATORY CONDITIONS
F. L. Mantelatto1, A. L. D. Reigada2 and J. A. Cuesta3
1
Laboratory of Bioecology and Crustacean Systematics, Department of Biology, FFCLRP, University of São
Paulo (USP), Av. Bandeirantes 3900, CEP 14040-901, Ribeirão Preto (SP), Brazil.
2
UNESP, Campus de São Vicente, São Vicente, SP, Brazil.
3
ICMAN, CSIC. Avenida República Saharaui, 2, 11519 Puerto Real, Cádiz, Spain; email of presenting author:
jose.cuesta@icman.csic.es
The genus Callinectes Stimpson, 1860 currently consist of 15 species, 6 of which are reported
in the Brazilian waters. In the present study the first zoeal stage of Callinectes bocourti, C.
danae, C. exasperatus, C. ornatus and C. sapidus from Brazil were obtained from ovigerous
females. The morphological and meristic characters of all these larval stages are described
and illustrated. Those of C. sapidus and C. danae are re-described and compared with the
previous first descriptions, and differences are listed. Larval characters of these species are
compared looking for interspecific differences, as well as larval features to allow distinguish
the genus Callinectes within Portunidae. Also comparisons are made with the rest of portunid
genera and species with first zoeal stage known, with special interest in those species present
in the same geographical area. Our findings are in concordance with some previous molecular
studies and we discussed the complexity within the group.
GROWTH OF DUSKY GROUPER (Epinephelus marginatus) LARVAE REARED IN A
MESOCOSM
H. Quental1, M. E. Cunha1, A. Barradas1, E. Cabrita2, S. Engrola2 and P. PousãoFerreira1
1
INRB/IPIMAR-Olhão, Av. 5 Outubro s/n 8700-302 Olhão, Portugal; email of presenting author:
hferreira@cripsul.ipimar.pt
2
CCMar,Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
Dusky grouper, Epinephelus marginatus (Lowe,1834), is classified as an endangered species
by the International Union for Conservation of Nature and Natural Resources (IUCN) and has
generated considerable interest for the European Aquaculture Institutions, mainly with the
objective of stock enhancement. Larval rearing of this species is still a major challenge since
early larvae have mouth gapes too small for the common live feed used in aquaculture. In this
work we present results on the growth of E. marginatus larvae performed in a mesocosm
system. This technology relies on the enhancement of a natural pelagic food chain,
particularly copepods, in a confined system, with variable prey sizes and high nutritional
value. Larvae were reared in a shaded 3 m3 circular outdoor tank during July and August
2007. Water from the Ria Formosa coastal lagoon (Algarve, Portugal) was supplied directly
to the tank in a continuous slow flow (0.2 L.min-1). Before introducing the larvae to the tank
the water was left to stand for five days to promote growth of zooplankton populations.
8th Larval Biology Symposium
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Morphology, larval development and growth
Poster
Larvae were obtained from artificially fertilised eggs of wild adult groupers kept in captivity
at the Research Aquaculture Centre. Around 4,000 larvae were introduced into the mesocosm.
Minimum food density was checked daily (1 L samples) and if the total zooplankton density
was lower than 200 individuals.L-1, small rotifers (Brachionus plicatilis) were also supplied
(for the first 3 weeks) followed by Artemia spp.. Mean water rearing temperature, dissolved
oxygen, pH and salinity averages were 24.47 ± 1.38 ºC, 7.23 ± 1.18 mg-O/L, 7.98 ± 0.35 and
35.57 ± 1.01, respectively. Daily water renewal was 10% until 15 days after-hatching (DAH),
25% between 15-30 DAH and increased to 100% until the end of the rearing (37
DAH).Larval growth was determined using total length of recently dead larvae. Growth is
exponential and from 23 DAH, until 37 DAH (a few days before metamorphoses) the growth
model was y = 3.1e0.051x, where y is total length and x is age in days.
HISTOLOGICAL AND MORPHOLOGICAL EVALUATIONS OF THE DIGESTIVE
SYSTEM OF NATIVE CICHLID BAY SNOOK PETENIA SPLENDIDA DURING
EARLY ONTOGENY
L. Treviño1, C. A. Alvarez-González2, E. Gisbert1, N. Perales-García2, L. ArévaloGalán2, G. Márquez-Couturier2 and A. Uscanga-Martínez2
1
IRTA – Sant Carles de la Ràpita, Crta. Poble Nou km 5.5, 43540 Sant Carles de la Rapita, (Tarragona), Spain;
email of presenting author: enrich.gisbert@irta.es
2
DACBIOL Lab. Acuacultura, Universidad Juárez Autónoma de Tabasco, Crta. Villahermosa–Cárdenas km. 0.5,
Villahermosa, Tabasco 86039, Mexico
Although fish culture is one of the fastest growing productive activities world-wide, culture of
Mexican native cichlids have been scarce. Cichlid species of commercial importance such as
Tenguayaca Petenia splendida (Günther, 1862) are found in southeastern Mexico and have
been studied for many years. Their distribution, biology and ecology are recently known and
studies for their commercial culture are lately being carried out. The massive rearing of P.
splendida larvae has been limited because the studies of the ontogenetic development of the
digestive system have not been carried out that allow to understand the type of foods (live or
inert), and the appropriate moment to feed larvae should be used.
We studied the ontogenesis of the digestive system by histological and morphological
evaluations of native cichlid Petenia splendida from hatching (0 dah, days after hatching)
until 60 dah. Tenguayaca larvae were obtained from spawnings from a broodstock kept in
captivity at the UJAT-DACBIOL facilities. After hatching (3 days post fertilization) yolk-sac
larvae were placed into a 1000 l tank (0.75 larvae l-1) connected to an open water system
(29ºC, 6.5 mg O2 l-1, pH 7.4). Larvae were feed to satiation four times per day with Artemia
nauplii from the mouth opening (3 dph) until 15 dph. Later on, larvae were fed three times per
day with a dry trout diet (Silver Cup, Nelson & Sons, Inc.) until day 60 dph. For
morphological evaluations of intestinal development, every two days, five larvae were
collected with a 500 µm diameter net. Larvae were anaesthetized with tricaine
methanesulphonate (MS222), rinsed with distilled water and fixed with formalin 4%
neutralized with borates until histological analysis. Larvae and post-larvae were embedded in
paraffin blocks. Each block contained from 2 to 5 larvae. Serial sagittal, longitudinal and/or
8th Larval Biology Symposium
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Morphology, larval development and growth
Poster
transverse sections cuts using a Leica RM 2155 rotary microtome, cuts from 3 to 5 µm thick
from whole specimens were placed on uncoated glass slides and baked overnight at 40 ºC.
Subsequently sections were stained with Haematoxylin-Eosin for general histomorphological
observations. The slides were mounted using Eukitt (Fluka 03989 BioChemika) and were
examined and photographed with a light microscope (Leica DMLB).
Our results showed the development of the digestive system of Petenia splendida based on
morphological and histological characteristics into three phases: 1a) cell proliferation and
morphogenesis of digestive structures, 2a) complete morphogenesis of digestive organs and
accessory glands, 3a) growth in size and volume of digestive organs and accessory glands.
Extra Abstract for Oral presentation in session: Ecology, recruitment and settlement
SETTLEMENT CUEING AND SPATIAL DYNAMICS IN THE NEW ZEALAND
HALF CRAB, Petrolisthes elongatus.
Nicolai Truemper
School of Biological Sciences/Te Kura Matauranga Koiora, Victoria University of Wellington, New Zealand,
New Kirk Building, Kelburn Parade, PO Box 600, Wellington 6140, New Zealand; email:
Nicolai.Truemper@vuw.ac.nz
Specific substratum selection due to chemical settlement cues or surface properties may lead
to aggregated (gregarious) settlement and can determine recruitment patterns. Both larval
supply and the often patchily distributed availability of suitable microhabitats have a strong
impact on the spatial variation in abundance of species. This is especially true for small
invertebrates, such as anomuran crustaceans, living among cobbles on intertidal boulder
fields. The results from choice chamber experiments provide strong evidence that adults of P.
elongatus release a chemical settlement cue, presumably a pheromone, that attracts
conspecific larvae. This evidence is supported by significantly different numbers of recruits in
cobble-filled basket traps deployed in the natural habitat that contained either 30 P. elongatus
adults or were empty (i.e. excluding migrating adults but allowing settlement): There was a 4fold greater settlement into baskets with adults. This attraction effect is density dependent and
results in gregariousness and patchiness of settlement on a small scale (tens of centimeters).
Further, I assessed the heterogeneity of rock-size distribution as well as the patchiness of
abundance of P. elongatus on four different spatial scales, ranging from centimeters to
kilometers, using 0.5m x 0.5m quadrats in a nested design including three sample sites in the
Wellington region. The examination of gregariousness and aggregation leads to broader
considerations concerning trade-offs between aggregation and density dependence.