Changes in the abundance and distribution of SAV along Florida’s springs coast: a comparison based on
aerial photography acquired in 1992 and 1999
Jason A. Hale* and Thomas K. Frazer. University of Florida, Department of Fisheries and Aquatic Sciences, 7922
NW 71st Street, Gainesville, Florida, 32653, USA; e-mail jah@gnv.ifas.ufl.edu; frazer@ufl.edu.
Two sets of approximately 100 aerial photographs each were interpreted for SAV coverage along Florida’s Springs
Coast (from Anclote Key to the mouth of the Withlacoochee River) to describe differences in abundance and
distribution between 1992 and 1999. Both data sets were interpreted using a modified Braun-Blanquet scale of
vegetation abundance. The original ground-truth data were collected as estimates of SAV cover per square meter:
up to 25% coverage = Braun-Blanquet class 2; 25% - 50% coverage = BB class 3; 50% - 75% coverage = BraunBlanquet class 4; and greater than 75% coverage per square meter = Braun-Blanquet class 5. This classification
scheme is quantitative, can be adapted to changes in project purpose or in response to preliminary accuracy
assessments, and is commonly used by other investigators.
We interpreted approximately 1000 km2 of benthic habitat from the 1999 set of photographs. About half of this area
was determined to have at least 25% SAV coverage, and about one third of the total area was greater than 75%
coverage. Over half of SAV coverage in 1999 occurred in water less than about 1 m deep, while approximately
20% occurred in water greater than 2 m in depth. About 750 km2 of nearshore bottom was common to the two sets
of photographs and available for change analysis. . Approximately twice as much area of SAV thickened as thinned
from 1992 to 1999. Notable areas of SAV thinning occurred near Tarpon Springs, as well as areas adjacent to the
Weeki Wachee and Crystal rivers. Conversely, SAV adjacent to the Homosassa River and St. Martins Keys
thickened between 1992 to 1999. When analyzed with respect to depth intervals, areas thickened exceeded areas
thinned by about 2 to 1.
Fragments of the seagrasses Halodule wrightii and Halophila johnsonii as potential recruits in Indian River
Lagoon, Florida
Lauren M. Hall,1* M. Dennis Hanisak,2 and Robert W. Virnstein.3 1St. Johns River Water Management District,
525 Community College Pkwy, Palm Bay, FL 32909, USA; 2Harbor Branch Oceanographic Institution, 5600 US1
North, Fort Pierce, FL 34946, USA; 3St. Johns River Water Management District, PO Box 1429, Palatka, FL
32178, USA.
The concept of vegetative seagrass fragments as a dispersal and recruitment mechanism in Indian River Lagoon,
Florida has not been explored. Research on the potential of vegetative fragments can help us better understand the
ability of seagrass beds to recover from disturbance events. The objectives of this study are to: (1) determine the
viability of drifting Halodule wrightii and Halophila johnsonii vegetative fragments as a function of time, (2)
examine the seasonal aspect of recruitment potential, (3) determine if the source of the H. johnsonii fragments
influences viability (4) determine how fragment position in the water column is influenced by time, and (5)
determine the frequency of fragment rooting versus time.
Mesocosm experiments demonstrate that H. wrightii fragments remain viable for up to 4 weeks with a marked
decline in success after 2 weeks of drifting during spring. Fall plants had a shorter period of viability with only 5%
of fragments remaining viable by week 2. Although the source of the fragment did not influence viability for H.
johnsonii, day and season was highly significant, with spring plants remaining viable for up to 4 days and fall
remaining viable for twice as long. The short viability of H. johnsonii illustrates the importance of rapid settlement
when uprooted from a source bed, limiting dispersal to shorter distances. H. wrightii appears to maintain its
viability for a longer period of time, indicating that this species may be able to utilize fragments as a dispersal
mechanism over longer distances. The fragments’ positions in the water column followed a trend with a decrease in
floating fragments while sediment level and rooting fragments increased over time. Both H. wrightii and H.
johnsonii had the ability to settle and root on their own, indicating that this may be a recruitment mechanism
occurring for these species.
The effects of zinc on arm regeneration rates and tissue development patterns in the brittlestars Ophiothrix
angulata and Amphipholis gracillima
Rosemary E. Hall* and Steve E. Stancyk. Marine Science Program, University of South Carolina, Columbia, SC
29208, USA.
Brittlestars are cosmopolitan echinoderms that are key in ecosystem dynamics. They can influence habitat structure
and are important food sources for some fish, crabs, and shrimp. Burrowing species in particular affect infaunal
communities by aerating their burrows. Because of their ability to rapidly regenerate injured or autotomized arms,
they can also show the effects of toxicants even after a pollutant’s concentration has decreased in the environment.
Zinc is of particular interest because it is a common pollutant, yet has a natural role in nervous system and enzyme
function. Toxic levels of zinc can be expected to inhibit nervous function and therefore interfere with regeneration.
In this investigation, we hope to examine the potential for using regenerating species to observe effects of toxicants
in an environment, and to further investigate patterns of regeneration as they may relate to the ophiuroid nervous
system. In initial rangefinder experiments, we found that environmentally relevant concentrations of zinc caused
rapid mortality. Furthermore, increasing, nonlethal concentrations of zinc were associated with decreasing rates of
regeneration in both species.
Using automated sampling equipment and estuary scale modeling to investigate the physical-biological
coupling of larval transport
John F. Hamilton,1* Robert B. Whitlatch,1 and Richard W. Osman.2 1University of Connecticut, Groton, CT 06340,
USA; 2Academy of Natural Sciences, St. Leonard, MD 20685 USA, USA.
For many benthic invertebrates a free-swimming larval stage links a reproductively active adult to the successful
establishment of a new sessile individual or colony. Larvae range from those that are long lived and dispersed
regionally to those that are short lived and dispersed more locally. For those species with a short lived larval stage,
the success at colonizing a suitable habitat may be strongly influenced by the pattern of tidally induced water
movement and the availability of reproductively active adults upstream of the selected site.
We have been utilizing colonial ascidians that feature a short lived larval stage to discern the extent to which
recruitment success is coupled to tidal flow patterns for this type of life history. We utilize a system of automated
sampling equipment to help investigate the relationship between the biological and physical processes of larval
release, larval transport, and settlement. The equipment exposes substrates to the water column to collect
individuals settling out of the plankton, separating the settlement activity into distinct portions of the tidal cycle. A
survey of the estuary provides an estimate of the likely source regions; this information is coupled with known life
history traits and a hydrodynamic model to predict the extent of settlement at the locations of the automated
instruments. Comparison of the model predictions to the results from the sampling equipment indicates that the
modeled processes are responsible for only a portion of the population dispersal in this system.
Genetic evidence for an apicomplexan-Dichocoenia sp. association
Andrew R. Hannes,* Tamar L. Goulet, and Mary Alice Coffroth. Department of Biological Sciences, State
University of New York at Buffalo, Hochstetter Hall, Buffalo, New York 14260-7022, USA.
Several lines of evidence suggest that organisms from the phylum Apicomplexa are found in association with
marine host-algal symbioses. We provide genetic evidence suggesting the presence of an apicomplexan in a
scleractinian host and suggest that these associations may be a common occurrence in reef cnidarians. Analysis of
the small subunit ribosomal DNA (18S-rDNA), amplified from the scleractinian, Dichocoenia sp. using a
zooxanthellae specific primer set, yielded a previously uncharacterized restriction fragment length polymorphism
(RFLP) genotype. RFLP of 18S-rDNA is the generally accepted technique utilized for cladal classification of
zooxanthella. For this reason, it is important to determine what organism is responsible for this aberrant genotype. A
phylogenetic analysis of 18S-rDNA nucleotide sequences from a variety of apicomplexans and dinoflagellates, as
well as, the suspect sequence showed that the organism responsible for the uncharacterized genotype is most closely
related to protozoans of the phylum Apicomplexa, order Coccidia.
Sliding baselines, stealth predators, and cascading impacts to functional responses in Gulf of Maine benthic
communities
Larry G. Harris.* Zoology Department, University of New Hampshire, Durham, NH, USA.
Over the last 30 years, benthic communities in the Gulf of Maine have undergone major shifts in composition. Kelp
bed communities gave way to urchin barrens about 1980 and overfishing of sea urchins has been followed by the
reestablishment of algal dominated communities. The new algal communities have included a series of
opportunistic and invasive species not present in previous kelp bed systems. The most drastic changes in
community composition has occurred in the southeastern portion of the Gulf of Maine, where kelp beds are being
replaced by Codium beds with an understory dominated by invasive red algae, blue mussels, and two invasive
colonial tunicate species. The introduced bryozoan Membranipora is a dominant epizooite on a wide variety of
algal species. The structure, composition, and interactions within this new community state are changing quickly as
associated fauna and flora respond to newly abundant substrates and food sources. Extensive subtidal Mytilus beds
have facilitated increased sea star, crab, and wrasse populations as well as two flat worm species, the invasive acoel
Convoluta and the poorly studied polyclad Notoplana. The Common Eider is also a major neglected predator on
mussels and other benthic fauna. The combined predator load has shifted the role of mussel beds from dominant
space occupiers into ephemeral disturbance events. Predator increases are also impacting herbivore populations that
may favor ephemeral algae over the previous climax species in these communities.
Growth rates of juvenile pinfish (Lagodon rhomboides): effects of habitat and predation risk
Stacey L. Harter* and Ken Heck, Jr. Dauphin Island Sea Lab, University of South Alabama, USA.
Predation is often one of the largest sources of mortality for juvenile fishes and, because of this, many young fish
exhibit rapid growth that allows them to outgrow predators. However, predation risk often forces young fish into
suboptimal foraging habitats, thereby compromising rapid growth. Field caging experiments were performed in Big
Lagoon, Florida to examine the effects of flounder predation risk on the growth rates of juvenile pinfish in three
different habitats: sand, low density, and high density of shoal grass (Halodule wrightii). Preliminary results suggest
that the interactions between growth rates, habitat, and predation risk vary with season. During late spring-early
summer, pinfish grew the most in seagrass habitats and predation risk significantly reduced growth. However,
during the fall, pinfish grew most in sand and predation risk did not significantly affect growth. We conclude that
when pinfish are smallest and most vulnerable, predation risk reduces growth rates, but as pinfish reach a larger size
(> 80 mm TL) it appears they approach a size refuge from predation.
A comparison of growth rates of juvenile Callinectes sapidus along a salinity gradient in the Cape Fear River
estuary
Heather Harwell,* Martin Posey, and Troy Alphin. Department of Biological Sciences, University of North
Carolina at Wilmington, Wilmington, NC, USA.
The blue crab Callinectes sapidus is a euryhaline estuarine species that copes with rapidly changing environmental
conditions including varying temperatures and salinities. Although settlement may occur predominantly in
euryhaline areas, juvenile and adult blue crabs are found across the estuarine gradient. Potential osmoregulatory
costs of occurring in low salinity water raises questions about potential effects on growth. This question may be
particularly important for juveniles that have high surface area to volume ratios and that receive decreasing
predation pressure with increasing size. We conducted a field experiment measuring growth rates of juvenile blue
crabs across the estuarine gradient examining effects of salinity and covariant factors on growth and survival. Five
sites along the Cape Fear River in southeastern North Carolina were selected. Those sites represent salinity ranging
from full strength seawater to oligohaline regions of the upper river. Juvenile crabs (15-30 mm CW) were placed in
individual cages at each location for a twelve-week period, in summer and again in fall during which carapace width
measurements were made weekly. Infaunal and sediment cores were also taken at each site in order to examine
possible food availability and grain size distribution. Crabs placed at the low salinity site (0 ppt) suffered high
mortality and could not be used for growth evaluation. Percent growth was similar at all other sites, although the
average period of intermolt was 14 days at sites of lower salinity (5.3 and 14.4 ppt) and 24-27 days at higher salinity
sites (18.2 and 22.1 ppt). Fall results for percent growth were similar to those of summer. There was, however, an
overall increase in intermolt period and mortality in fall compared to summer.
Utilizing a seabed classification system, RoxAnnTM, to monitor changes in a biologically created benthic
habitat
Olivia A. Hauser* and Douglas C. Miller. University of Delaware, Graduate College of Marine Studies. 700
Pilottown Rd. Lewes, DE 19958, USA; e-mail ohauser@udel.edu.
RoxAnn, a seabed classification system, has the power to map various bottom types by interpreting the strength and
shape of a sound signal echoed from the bottom. This system plots the first and second echoes (E1 and E2) on a
Cartesian graph and classifies bottom types by E1 and E2 combinations. E1 is a proxy for bottom roughness while
E2 is a proxy for bottom hardness. A 5-km2 area of Delaware Bay, Delaware was surveyed in once in September
2000 and again in January 2001 and the resulting images compared. The five bottom types (tubeworm nodules,
mussels, gravel, fine sand and coarse sand) were identified and ground truthed with sixteen sediment grabs in the
first survey and three grabs in the second survey. The distribution of RoxAnn classified bottom types was not
notably altered between surveys, which was confirmed with the sediment grab samples. While consistency in
classification indicates a stable benthic habitat, the individual plots of E1 and E2 values indicated changes in the
bottom properties. Bottom roughness (E1) stayed relatively constant while bottom hardness (E2) differed between
the two survey dates. Since the ground truthing confirmed the bottom types stayed the same, we have concluded that
seabed roughness (E1) was a better proxy for benthic bottom type than seabed hardness (E2). Overall, RoxAnn was
found to be an effective technique to map this benthic hard bottom habitat found in Delaware Bay.
Tough decisions—having sex or being dinner: the dilemma for some tropical seaweeds
Mark E. Hay* and Julia Kubanek. School of Biology, Georgia Institute of Technology, Atlanta, GA 30332-0230, USA.
When tropical green seaweeds in the genus Halimeda become reproductive, both generalist herbivorous fishes and
specialist ascoglossan gastropods begin consuming reproductive plants at rates of 5-10 times the rates that they consume
vegetative plants. These seaweeds appear to invest about 1/3 of their total ash-free-dry-mass in reproduction over a
period of several hours, and then die. During the time that they are maturing gametes on their surface, they contain
higher concentrations of secondary metabolites that have previously been identified as feeding deterrents, but they are
none-the-less consumed at higher rates than are vegetative plants. Rapid field bioassays of lipid extracts from vegetative
versus reproductive plants show that vegetative plants are more chemically resistant to fishes, but this chemical
difference is lost if extracts are held for more than a few hours, suggesting rapid degradation of active metabolites.
Follow-up efforts to stabilize activities and specific compounds using different extraction solvents and procedures were
unsuccessful at determining which chemical changes were affecting differential palatability of vegetative vs.
reproductive plants, but did indicate that methodologies did strongly affect the secondary metabolites obtained.
Maturation of gametes, chemical changes of defenses within the plant, and susceptibility to herbivores all change rapidly
throughout the afternoon and evening immediately before synchronous release of all gametes at about sunrise.
Following gamete release, the white, apparently dead, skeletons of Halimeda are immediately consumed by fishes. The
tremendous rates of grazing on reproductive plants may have selected for Halimeda to allocate all mobalizable resources
to reproduction, even though this leads to plant death.
The effect of prey density on zooplanktivory by the burrowing ophuiroid Hemipholis elongata (Say, 1825)
F. C. Helies* and S. E. Stancyk. Marine Science Program and Department of Biological Sciences, University of
South Carolina, Columbia, SC 29208, USA.
The ophiactid brittlestar Hemipholis elongata readily captures brine shrimp and copepods from the water column
with its extensible, sticky tube feet. To develop a feeding response curve, we tested the effect of prey density on the
rate of prey capture by individual brittlestars. Following acclimation, brittlestars of approximately the same size
were allowed to bury, each in individual 6 cm diameter plastic cores filled with muddy sand. Each core was placed
in a separate battery jar containing 4000ml of 35 ppt seawater and a bubbler. Over several trials, each individual
was given 50, 100, 200 and 500 brine shrimp (Artemia salina) and allowed to feed for half an hour. In each trial,
control battery jars were run for each prey density. The brittlestars were then removed and the remaining Artemia
were collected on sieves, preserved and enumerated. The data were compiled to determine consumption rates and
the type of feeding response curve the brittlestars demonstrated.
Star-crossed sponges: the sponge-brittlestar association between Callyspongia vaginalis and Ophiothrix
lineata
Timothy P. Henkel* and J. R. Pawlik. Biological Sciences and Center for Marine Science, University of North
Carolina at Wilmington, Wilmington, NC 28409, USA.
On coral reefs cryptic species form regular and intimate associations with sessile benthic invertebrates for refuge
from predation in a space-limited environment. In a recent survey of sponge-dwelling ophiuroids in the Florida
Keys, the deposit feeder Ophiothrix lineata was found to occur almost entirely in the common tube sponge
Callyspongia vaginalis. Local abundances of O. lineata increased with the presence of C. vaginalis, and brittlestars
were partitioned by size class on individual sponges, with large individuals (> 5 mm oral disk diameter) only
occurring inside sponge tubes. In field manipulations, O. lineata actively selected C. vaginalis over non-living
refuge or the sponge Niphates digitalis. Large O. lineata remained in an individual sponge for up to 3 months, and
abundances of large individuals never exceeded the number of tubes per sponge. This study provides evidence that
O. lineata may be a species-specific sponge commensal, and suggests that access to feeding surfaces and refuge
from predation may regulate habitat partitioning in O. lineata.
Emergency restoration of significant seagrass injuries: a case study from North Sound, Grand Cayman,
B.W.I.
Mark Henry,1* Adam Gelber,1 William Precht,1 Martin Heaney,2 Lisa Vitale,3 and Beth Zimmer.1 1PBS&J, 2001
N.W. 107th Ave., Miami, FL 33172, USA; 2PBS&J, 1880 South Dairy Ashford Street, Suite 300, Houston TX 77077,
USA; 3PBS&J, 206 Wild Basin Road, Suite 300, Austin, TX 78746, USA.
In North Sound, Grand Cayman, large monospecific beds of Thalassia testudinum abound. During the installation
of a series of submarine power cables, localized patches of this seagrass were injured by the mechanical operations.
In all, four scars each measuring approximately 1 m in width by 1 m depth by 50 m in length were identified and
assessed using standard scientific diving techniques. Where sufficient substrate has been removed in such a
disturbance event, the natural recovery of the T. testudinum is usually small or nonexistent. The inability of this
seagrass to re-colonize a deep trench or depression is due to the vegetative propagation of the rhizomes. These
creeping rhizomes extend horizontally through the sediment with new leaf-bearing shoots growing off the apical
meristems. If no sediment is present where the rhizome extends, the rhizome stops growing, failing to reorient into
the depression. If this sediment is not replaced, these depressional scars remain as permanent features over temporal
scales of multiple decades or longer. To prevent this protracted recovery, an emergency restoration plan was
implemented within 72 hours of the actual injury. Using a team of commercial divers, inert fill (clean sand) was
placed in the elongate troughs, followed by the replacement of sediment and seagrasses that had been pushed up in
berms along the edge of the scars. Within two weeks, the outline of the original injury was almost indistinguishable
from the surrounding unimpaired seagrass meadow. Follow-up monitoring of multiple biotic indices some nine
months after the original injuries shows complete restoration. This project highlights the importance of early
intervention in seagrass restoration and the need for replacement of lost sediment to accelerate the recovery process.
Do sediment disturbance processes structure estuarine soft sediment communities?
Elizabeth K. Hinchey* and Linda C. Schaffner. School of Marine Science, The College of William and Mary,
Virginia Institute of Marine Science, Gloucester Point, VA 23062, USA.
We are investigating the role of sediment disturbance processes in structuring low diversity soft sediment benthic
communities. Field studies conducted in two Chesapeake Bay tributaries examined effects of sediment disturbance
events on seabed dynamics and associated macrobenthic recruitment success and community structure. The York
River, characterized by relatively high tidal energy, experiences deep sea-bed mixing over various time scales due to
erosion and deposition processes. Multi-year comparisons at the York River study region revealed that more severe
sediment disturbance events were observed during a high discharge, wet year vs. low discharge, drought conditions.
During the drought, effects of sediment disturbance were most pronounced in deep channel environments where
tidal currents are strongest, as opposed to wet years when sediment disturbance was observed in channel, flank and
shoal environments. Sites demonstrating evidence of recent reworking of near-surface sediments exhibited
depressed abundances of sedentary infaunal organisms and were dominated by motile fauna. The Patuxent River
experiences minimal sea-bed mixing as a result of an order of magnitude lower tidal energy; sites in this system
were populated by a combination of sessile tube builders and motile fauna. Effects of sediment deposition on
estuarine macrobenthic organism growth and survival were further investigated in laboratory experiments. We
tested response to overburden stress due to burial for a sedentary tube-dwelling species (Streblospio benedicti) and
motile shallow burrowing species (Leptocheirus plumulosus) and motile deep burrowing species (Macoma balthica).
Mortality was correlated with motility mode, with Streblospio benedicti and Leptocheirus plumulosus exhibiting
significant, but differential, mortality. Macoma balthica did not suffer any burial-induced mortality at the levels of
overburden stress tested. Our results suggest that tidal flow-mediated disturbance can be a strong structuring force
in energetic estuaries, at sites where tidal currents are strongest and during events when fine-grained sediment input
via the spring freshet is enhanced.
Analysis of Biscayne Bay sediments: do benthic Foraminifera of the bay reflect trace metal contamination?
A. M. Hoare,1* P. Hallock,2 B. H. Lidz,3 C. D. Reich,3 and E. A. Shinn.3 1College of Marine Science, University of
South Florida, 140 7th Ave. S., St. Petersburg, FL 33701, USA; 2College of Marine Science, Faculty of Marine
Science, University of South Florida, 140 7th Ave. S., St. Petersburg, FL 33701, USA; cU. S. Geological Survey, 600
4th St. S., St. Petersburg, FL 33701, USA.
The human population explosion in South Florida over the past hundred years has brought significant changes to
Biscayne Bay, many of them detrimental to the coastal ecosystems. The construction of bridges, canals and
causeways degraded shorelines and altered benthic communities. Raw sewage effluent and chemical pollutants have
also degraded the bay. Although discharge of untreated sewage has been addressed and the Toxic Substance
Control Act was enacted, trace metal pollution remains an issue of concern. Numerous studies carried out in both
temperate and tropical regions have shown that benthic foraminiferal assemblages are efficient indicators of trace
metal pollution. In addition, shell aberrations typically occur in sediments that are highly contaminated with trace
metals. The objectives of this study were to analyze sediments of Biscayne Bay for trace metal contamination and
determine whether benthic foraminiferal assemblages reflect contamination and indicate hotspots of pollution.
Thirty-eight sites in Biscayne Bay were sampled for surficial sediments. Analysis of the sediments consisted of
geochemical assessment for 30 chemical parameters, grain-size analysis and micropaleontological assessment of
foraminifera at the genus level. Geochemical analysis revealed that effects range low (ER-L) values, and in some
cases, effects range median (ER-M) values for several trace metals were exceeded at several nearshore sites in the
upper bay. Three assemblages of foraminifera were identified. Sediments of finer grain size were dominated by
opportunistic taxa, whereas those of large grain size consisted of other smaller foraminifera. Sites farthest offshore
from Black Point had higher percentages of symbiont-bearing foraminifera. Although shell aberrations were present
in several samples, the percentages of deformed specimens were low and deformations were not concentrated near
or at the hotspots of chemical contamination.
Growth and survival costs of aggression in juvenile Hemigrapsus sanguineus crabs
Niels-Viggo S. Hobbs.* Biological Sciences Department, University of Rhode Island, Kingston, RI 02881, USA.
Aggression in decapod crustaceans is well studied but the associated long-term costs have yet to be fully explored.
Costs are a critical component of any analysis of risk assessment in the decision-making process of animals. To
identify how aggression impacts growth, survival and injury, and thus presumably affects behavior, a long-term
growth study was done of juvenile Hemigrapsus sanguineus crabs. treatments were comprised of individuals paired
together for different lengths of time each day (simulating actual encounters rates) from post-settlement to the onset
of maturity. In treatments with higher encounter rates, H. sanguineus showed a significant decrease in survival and a
greatly increased injury rate. In addition, growth was significantly slowed in these same groups, further indicating
clear costs of agonistic behavior. Analysis of how aggression affects timing of maturity and fecundity is presently
underway for this and other decapod species, and should provide a more complete picture of the toll aggression can
take on fitness and growth.
Invasive green porcelain crabs, Petrolisthes armatus, on oyster reefs in the South Atlantic Bight: friend or foe?
Amanda L. Hollebone1* and Mark E. Hay.2 School of Biology, Georgia Institute of Technology, 310 Ferst Drive,
Atlanta, Georgia 30332-0230, USA; 1e-mail gte276s@prism.gatech.edu; 2e-mail mark.hay@biology.gatech.edu.
Biological invasions can be a threat to natural communities and a major force in determining ecosystem structure
and function. The recent invasion of Petrolisthes armatus into southeastern oyster reefs raises questions concerning
the crab’s impacts on non-native habitat and reasons for its abundance and success. Our research addresses the
ecological implications of the invasion as well as the ecosystem’s susceptibility to invasion. Habitat choice assays
with live and dead oyster clumps, single live and dead oysters, and combinations thereof, indicate that P. armatus
significantly chooses to associate with clumped live oysters over all other options. This choice appears to be guided,
in part, by chemical and/or visual cues. Crabs significantly choose oysters with a biofilm over those where it is
mechanically removed; this distinction disappears as the biofilm reforms over time. Tethering experiments suggest
that predation pressure on adult crabs can be intense (0-10% survival in mud flats without shelter, both day and
night, 0-10% survival within live oysters during the day, and 20-67% survival within live oysters at night, depending
on crab size), and laboratory assays suggest that P. armatus is palatable to native predatory crabs. Despite their
relatively small size, reproductive females (5-10 mm carapace width) brood tens to hundreds of large, spine-bearing
larvae (8-10 mm). Laboratory assays suggest that neither filter-feeding adult crabs nor oysters feed on these larvae.
Initial mass spectrometry data (13C and 15N) indicate that the crabs do not consume crude seawater filtrate, oyster
feces, or oyster biofilm. Thus, they may be actively distinguishing between food particles in the water column.
Because we do not know much about the crab in either its historic range (tropical Atlantic - eastern Pacific) or
recently expanded range, we cannot predict possible impacts on temperate oyster reefs unless we begin to
understand the crab’s life history and ecology.
The influence of Diadema antillarum recovery on the growth and survivorship of scleractinians on a Jamaican
coral reef
Joshua A. Idjadi1* and Nick Haring.2 1University of Delaware, Newark, DE, USA; 2California State University,
Northridge, CA, USA.
Since the late 1950’s, the cover of reef building corals on many Caribbean reefs has sharply declined in favor of
high macroalgal cover. These changes probably were caused by multiple natural and anthropogenic disturbances
including, perhaps most importantly, the region-wide mortality of Diadema antillarum. However, after nearly two
decades there are signs of Diadema recovery in Jamaica. Diadema can now be found on the forereef in dense
“zones” (~ 5 urchins/m2) characterized by low macroalgal cover and increased numbers of juvenile corals (< 4 cm in
diameter): the presence of Diadema is associated with an increased density of scleractinians. In this study, we
addressed two hypotheses to explain this relationship: (1) can juvenile coral success in urchin zones be attributed to
higher growth rates, or (2) is increased success of juvenile corals driven by reduced mortality in these zones? To test
these hypotheses, juvenile corals were tagged in urchin and algal zones at three locations at Discovery Bay, Jamaica.
Coral growth rates were determined by measuring the change in major diameter between January of 2001 and
January of 2002, and coral mortality was determined by counting the number of corals that died from one year to the
next. Standardized growth rates (using z transformations) for 7 scleractinian genera were significantly higher in
urchin zones when compared to algal zones (ANOVA, F1,2= 51.160 , p< 0.02). In addition, juvenile corals were less
likely to experience mortality in urchin rather than algal zones (chi-square, df=1, 2=6.257, p< 0.02). The results
indicate that corals are more successful in terms of growth and survivorship in the presence of Diadema. Thus, this
study underscores the potential importance of Diadema in the recovery of Caribbean coral reefs and provides more
“good news” for these coral communities.
Anthropogenic impacts and plant/plant interactions
E. Irlandi,* M. Reiber, and K. Taplin. Department of Marine and Environmental Systems, Florida Institute of
Technology, 150 West University Boulevard, Melbourne, FL 32901, USA.
The seagrass, Halodule wrightii, and the alga, Caulerpa prolifera, naturally co-occur in the Indian River Lagoon,
FL. Long-term monitoring, conducted by the St. Johns River Water Management District (Palatka, FL), indicates
shifts in abundance of the two species occurring over 6-month periods. In addition, Caulerpa often occurs in higher
abundance at greater water depths while Halodule is more common in shallower areas. We conducted field and
mesocosm experiments to evaluate the influence of light on potential competitive interactions between the two
species. Neighbor-removal experiments were conducted in the field at shallow and deep water depths as a proxy for
light. Removal of Caulerpa resulted in higher shoot densities and greater above-ground biomass of Halodule in
deep-water plots, while there was no effect of removal at shallow water depths. Caulerpa, however, showed no
difference in density or biomass in the presence or absence of Halodule in shallow- or deep-water plots, and it
occurred in greater abundance in deep water plots than in shallow. Mesocosm studies manipulating light regime
corroborated the results of the field experiment. Halodule grown alone under low light conditions demonstrated
higher shoot densities than when grown in combination with Caulerpa under low light conditions. Caulerpa frond
density was unaffected by the presence of Halodule regardless of light condition, and showed an inverse relationship
with light. These results suggest that anthropogenic effects that reduce water clarity and increase light attenuation
will produce conditions less favorable for Halodule than for Caulerpa
Fitness consequences of prey depletion for the common goby, Pomatoschistus microps
Angus C. Jackson,* Simon D. Rundle, and Martin J. Attrill. Department of Biological Sciences, University of
Plymouth, Drake Circus, Plymouth. PL4 8AA, UK; telephone + 44 (0)1752 232953; fax + 44 (0)1752 232927; email a.jackson@plymouth.ac.uk.
Pomatoschistus microps (Pisces: Gobiidae), a predatory, benthic feeder, occurs in high densities in variable,
shallow, muddy coastal waters where prey availability can be unpredictable. Here we investigate the effect and
consequences of prey depletion on the body condition and nest building of adult male fish using manipulative
mesocosm experiments in which the comparative value of meiofaunal and macrofaunal prey was investigated. Fish
maintained in mesocosms from which macrofauna had been removed from the sediment had a significantly reduced
hepatosomatic index (HSI) and were less likely to build nests than fish in mesocosms containing macrofauna and
meiofauna. HSI was also a good predictor of nest quality (i.e. entrance diameter), suggesting an indirect link
between prey availability and nest quality. This study suggests that reduced resource availability, in the form of
scarcity of macrofauna, may have profound implications for the fitness of natural field populations. As fish in
mesocosms from which macrofauna had been removed continued to feed, this reduced fitness may reflect a cost
associated with plasticity in feeding behaviour.
Habitat characteristics affecting fish and decapod assemblages of seagrass (Zostera marina) beds around the
coast of Jersey (English Channel)
E. L. Jackson,1,2* M. J. Attrill,1 S. J. Bossy,2 M. B. Jones,1 and A. A. Rowden.1,3 1Department of Biological
Sciences, University of Plymouth, United Kingdom; 2Department of Agriculture and Fisheries, States of Jersey,
English Channel; 3Present address: Marine Biodiversity Group, NIWA, Wellington, New Zealand.
Although it is widely accepted that seagrass habitats are important nursery areas, refugia and feeding grounds for
many species, including those of commercial value, little research establishing these roles has been conducted in
Europe. In particular, studies of British seagrass beds are lacking, even though their (presumed) importance is
highlighted in British fisheries management and conservation strategies (e.g. UK Biodiversity Habitat Action Plans).
This study examines the spatial utilisation of sub-tidal seagrass beds by fish and decapods in the coastal waters of
the island of Jersey in the English Channel. Previous results for total species richness and species density indicated
that variability between sites explained more variation than bed location. Thus, habitat characteristics of ten seagrass
beds were examined for potential influences on fish assemblage composition. Data for fish and decapods were
coupled with corresponding seagrass habitat variables (including bed size, percentage cover, shoot density, water
depth and sediment type), established from aerial photographic analysis, digital echo-sounder data and diver
surveys. The contribution of these variables as predictors of fish and decapod assemblage measures were evaluated
using multiple linear regression models. Comparisons are made with similar studies at different geographical
locations. These data are valuable in distinguishing and understanding potentially important processes, and can be
used by local fishery agencies to predict the relative importance of seagrass beds (to aid conservation designation) or
the consequences of different perturbation scenarios.
Barnacles to worms: periodic hypoxia in the Chesapeake Bay shifts community composition, but does it
facilitate invasion?
Elizabeth B. Jewett,1,2* Anson H. Hines,1 and Gregory M. Ruiz.1 1Smithsonian Environmental Research Center,
Edgewater, MD, USA; 2University of Maryland, College Park, MD, USA.
Hypoxia is increasing substantially in many marine and estuarine systems worldwide, primarily due to
anthropogenic causes. Using fouling organisms in the Chesapeake Bay as an experimental system, we tested the
hypothesis that periodic hypoxia (dissolved oxygen < 2 mg/l) may render the native fouling community more
vulnerable to invasion by non-indigenous species. Some organisms may thrive due to reduced predation while
others may capitalize on cleared space. PVC settling plates were deployed at shallow depths in spring 2001 at
Gloucester Pt, Virginia and were manipulated biweekly from late June to early August. Manipulation involved
placing individual panels in buckets and controlling DO (dissolved oxygen) levels (hypoxic, just above hypoxic and
normoxic) and time exposures (6h, 12h and 24h) according to a 3x3 factorial experimental design (n=8). MDS
(multi-dimensional scaling) results indicate a difference in the overall community composition according to DO
manipulation. Only those plates subjected to the lowest oxygen level showed a difference according to time
exposed with the communities exposed to hypoxia for 24 hours exhibiting a lower biomass and higher species
diversity. Hypoxia did not affect species richness but it did affect the relative abundance of the organisms present.
The percent cover of Hydroides dianthus, a native serpulid polychaete, increased with lower DO levels. The percent
cover of Molgula manhattensis, a solitary tunicate of cryptogenic origin, and of Ficopomatus enigmaticus, an
invasive serpulid, increased at the mid-DO level, which suggests an intermediate disturbance effect. According to
SIMPER (similarity percent routine) analysis, community dominance shifted from barnacles to polychaete worms as
hypoxia (and time exposed to hypoxia) increased. These findings may have implications for nutrient cycling and/or
food chain dynamics in systems that experience periodic hypoxic conditions.
Population dynamics and movement patterns of blue crabs in estuarine salt marshes
Eric G. Johnson* and David B. Eggleston. Department of Marine, Earth and Atmospheric Sciences, North Carolina
State University, Raleigh, NC 27695, USA.
A series of complimentary techniques were employed to quantify population demographics and describe patterns of
movement of juvenile and adult blue crabs, Callinectes sapidus, in two tidal salt marsh habitats located in the
Newport River estuary in Beaufort, NC during June - October of 2001. We tagged approximately 1,500 blue crabs
(21 – 148mm carapace width) with individually coded microwire tags, and used a Jolly-Seber capture-recapture
model to estimate population size, as well as probability of loss and recruitment. Microwire tags are an effective
method for tagging marine crustaceans, because they provide a permanent internal tag that is rarely lost through
molting, and the tag does not influence growth or mortality rates. Independent estimates of emigration were
measured through the use of block nets, which sampled crabs moving out of and into the study site, and sampling for
tagged individuals outside of the study areas. These independent estimates allowed us to partition crab loss from
salt marshes into mortality and emigration. To examine patterns of movement within the salt marsh, crabs were
tracked for 24-h using individually numbered floating tags that were affixed to the carapace of juvenile crabs (35- 68
mm CW). Juvenile crabs were mobile within the interstices of the marsh canopy during flood tide, and tended to
remain buried in mud within the marsh during ebb tide. Juvenile crabs exhibited a high degree of site fidelity to a
given marsh system during summer-fall, particularly smaller crabs, with the probability of mortality significantly
higher than emigration. These results provide important information on the nursery role of salt marsh systems.
Nekton utilization of intertidal marsh interspersed with micro-rivulets in Chesapeake Bay
J. M. Johnson* and D. L. Meyer. Center for Coastal Fisheries Habitat Research, National Oceanic and
Atmospheric Administration, 101 Pivers Island Rd, Beaufort, NC 28516, USA.
The use of intertidal marshes to provide refuge and a forage base for marsh resident nekton species such as Fundulus
sp. and Cyprinodon variegatus is well documented. In areas of northern Chesapeake Bay these intertidal marshes
are made up of hummocks of Spartina alterniflora and Phragmites australis interspersed by micro-rivulets. The
amount of channelization present in these marshes varies widely. During the course of a previous study comparing
nekton utilization of the two dominant intertidal marsh plant species, visual observations led to the hypothesis that
the amount of marsh channelization, due to the presence of these micro-rivulets, influenced marsh resident nekton
utilization. Subsequently the marshes were mapped to determine the amount of channelization present. All sites
were located in the Kent Narrows area of Chesapeake Bay and sampled in the spring, summer and fall of 1997-1998.
Regression analysis of the average combined densities of Fundulus sp. (F. heteroclitus, F. majalis, F. diaphanus, F.
luciae) and C. variegatus versus the area ratio of hummocks/micro-rivulets present in the front meter of the
marsh/creek interface indicated a quadratic relationship, accounting for 64% of the variation observed (p=0.045).
The optimal area ratio for resident nekton species indicated by the regression model was 35% hummocks/65%
micro-rivulets in the front meter of marsh. This suggests that the presence of these micro-rivulets, with the proper
degree of channelization at the marsh/creek interface, allows greater access to the marsh interior earlier in the flood
tide cycle for marsh resident nekton species while still offering protection from predation.
Photoresponses of Müller’s larvae of the flatworm Maritigrella crozieri
Kevin B. Johnson,1* and Richard B. Forward, Jr.2 1Department of Marine and Environmental Systems, Florida
Institute of Technology, 150 W. University Boulevard, Melbourne, Florida 32901, USA; 2Division of Coastal
Systems Science and Policy, Nicholas School of Environment and Earth Sciences, Duke University Marine
Laboratory, 135 Duke Marine Lab Road, Beaufort, North Carolina 28516, USA.
Larvae of the flatworm Maritigrella crozieri were examined for photoresponses, including spectral sensitivity,
ontogeny of the phototactic pattern, and intensity threshold. Adult M. crozieri feed exclusively and generally live on
the tunicate Ecteinascidia turbinata. They have a planktonic larval phase lasting longer than 3 weeks. We found
that the primary spectral sensitivity maximum was at 500 nm, which may be an adaptation to the spectrum available
underwater at twilight. The phototactic threshold changed with age; dark-adapted, young larvae (1 week old) had a
threshold an order of magnitude higher than that of older larvae (3 weeks old). Flatworm larvae are relatively
insensitive to light as compared to other invertebrate larvae. Young larvae were positively phototactic at high light
intensities and negative at low. This is a pattern typical of a predator avoidance shadow response. In contrast, older
larvae were only positively phototactic, which would be useful for transport to shallow-water adult habitats.
Habitat fragmentation in seagrass ecosystems: a preliminary investigation
Matthew W. Johnson* and Kenneth L. Heck, Jr. Dauphin Island Sea Lab, 101 Bienville Blvd., Dauphin Island, AL
36528, USA.
The role of habitat fragmentation is poorly understood in marine ecosystems. Previous work has concentrated
primarily on growth of selected bivalve species in seagrass habitats, and on animal abundances in different sized
patches of seagrass, algae, coral, oyster, and salt marsh habitats. Here, we present the baseline information gathered
from a project using Artificial Seagrass Units (ASUs) to examine the processes that control seagrass community
structure as patch size and shape change due to habitat fragmentation. ASUs, similar to those successfully used in
previous seagrass studies, were constructed of 1.9 cm black Vexar mesh and the seagrasses Thalassia testudinium
and Halodule wrightii were simulated using 5 mm and 2.5 mm green polypropylene ribbon. We placed ten replicate
ASUs of four combinations of shape and size 5 m apart and 5 m from any living seagrass in two study sites (Big
Lagoon, FL and Point Aux Pines, AL). ASU sizes were as follows: large stellate (area 0.2036 m 2, perimeter 1.6 m),
large circular (area 0.2036 m2, perimeter 3.265 m), small stellate (area 0.0487 m2, perimeter 0.7825 m), and small
stellate (area 0.0487 m2, perimeter 1.6 m). After four weeks, the entire ASU was sampled by placing an
appropriately shaped enclosure over the ASU and then removing the contents using a suction sampler. Preliminary
results indicated that patch size and patch shape can influence macrofaunal community structure in both Big Lagoon
and Point Aux Pines. However, our data indicate that perimeter:area ratios may be more important to ASU
colonization than either patch size or shape. This baseline information, combined with the results of other proposed
studies, should be helpful in making ecologically sound management decisions for the future conservation of
seagrass habitats.
Factors controlling the distribution of the green algal species Codium fragile at the Isles of Shoals
Adam C. Jones*1 and Larry G. Harris.2 1Providence College, Providence, RI, USA; 2Department of Zoology,
University of New Hampshire, Durham, NH, USA.
For a period of eight weeks during the summer of 2001, we investigated the association of the invasive green alga,
Codium fragile ssp. tomentosoides, with the sacoglossan gastropod Placida dendritica (Gastropoda:
Opisthobranchia) among the Isles of Shoals, off the coast of Portsmouth, NH USA. As the numerically dominant
predator on the algae, we examined possible means by which the population of the sacoglossan might be regulated,
and studied the correlation between C.fragile and P.dendritica densities in areas of variance in water motion. There
was a positive impact of water motion on the C.fragile, and a significant decrease in Codium density in locations
with high amounts of P.dendritica. However, we did not establish a relationship between water motion and the
number of P.dendritica present. Laboratory experiments and field observations showed the green crab Carcinus
maenus and the hermit crab Pagurus acadianus to be potential predators of P.dendritica, while similar trials with the
wrasse Tautogolabrus adspersus yielded negative results.
The effects of maternal care on dispersal and genetic population structure of western North Atlantic haustoriid
amphipods
Elizabeth Jones* and Scott C. France. University of Charleston, SC, USA.
Dispersal potential of larvae and juveniles plays an integral role in determining the population structure of many
shallow-water benthic marine invertebrates. This study attempts to determine how maternal care of juveniles in
amphipod crustaceans affects dispersal by examining the genetic population structure of several closely related
species that differ in levels of maternal care. Two species of interest are Neohaustorius schmitzi and N. biarticulatus.
These are free-burrowing haustoriid amphipods that inhabit the intertidal range of wave-protected sandy beaches
along the western North Atlantic coast. Like all peracarid crustaceans, these species brood embryos within a ventral
thoracic marsupium and possess direct development to a “crawl-away” juvenile stage. N. schmitzi is believed to
exhibit maternal care, since juveniles have been observed to return to the marsupium after hatching and have been
found within the marsupium of preserved specimens. The nature of maternal care in N. biarticulatus is currently
being characterized. Patterns of variation in the mitochondrial Cytochrome Oxidase I gene will be used to
determine the genetic population structure of both Neohaustorius species. We have sequenced approximately 600
base pairs of the COI gene from individuals in populations ranging from Cape Cod, MA to Charleston, SC. Sample
sizes need to be increased before inferences concerning gene flow and population structure can be made; however,
preliminary data suggests some genetic structure along the eastern coast of North America. Nine haplotypes have
been found in seven populations of N. schmitzi, with sequence divergences ranging from 0 to 1%. Among three N.
biarticulatus populations, two haplotypes have been seen, producing divergences ranging from 0 to 0.2%. Results
from this study will help determine whether amphipods with maternal care suffer from higher degrees of inbreeding
than those without, or conversely, if they benefit from greater dispersal due to higher juvenile survival rates.
Hydroid defenses against predators: importance of secondary metabolites vs. nematocysts
R. Channing Jones,1* John J. Stachowicz,2 and Niels Lindquist.1 1Institute of Marine Sciences, University of North
Carolina at Chapel Hill, Morehead City, NC 28557, USA; 2Section of Ecology and Evolution, University of
California, Davis, Davis, CA, USA.
Marine hydroids are benthic invertebrates commonly found in all the world’s oceans. These particle-feeding
invertebrates are commonly thought to be defended by organelles called nematocysts that penetrate predator tissues
and inject proteinaceous venoms. But not all hydroids possess penetrating nematocysts. The increasing number of
novel secondary metabolites isolated from marine hydroids suggests that some hydroids are chemically defended,
which our recent studies have confirmed. Furthermore, chemically defended hydroids typically lack penetrating
nematocyst, suggesting that unpalatable secondary metabolites and penetrating nematocysts represent alternative
defensive strategies for hydroids. To test this hypothesis more rigorously and to determine the prevalence of
chemical defense among hydroids, we have examined the palatability of hydroid polyps before and after
deactivating their nematocysts and the crude extract palatability of forty-five hydroid species from North Carolina
(temperate Atlantic), the Florida Keys (tropical Atlantic), California (temperate Pacific), and Papua New Guinea
(tropical Indo-Pacific). Our results to date suggest that chemical defenses may be at least as common as nematocystbased defenses among Florida and North Carolina hydroids and that the two represent largely alternative defensive
strategies. In contrast, only a small proportion of hydroids from California and Papua New Guinea have been
identified as chemically defended. The physical or biological causes of this apparent inter-ocean difference in the
prevalence of chemically defended hydroids is unknown. Given their alternative defensive strategies and the
apparent differences between Atlantic and Pacific faunas, hydroids offer an excellent system to investigate optimal
defense theory and the evolution of defensive strategies among marine organisms.
Predation rates on juvenile oysters: laboratory interactions between exotic and native crabs on prey size
selectivity
Michael L. Judge1* and Andrew A. Forbes.2 1Department of Biology, Manhattan College, Riverdale, NY 10471,
USA; 2Department of Biology, Colgate University, Hamilton, NY 13346, USA.
In the restoration of degraded marine habitats, the role of predatory exotic species is poorly understood. When
reliable evidence of interspecific interactions is lacking, restoration efforts may not be able to predict novel
community impacts. We examined the potential impact of the invasive Asian shore crab Hemigrapsus sanguineus
on attempts to re-establish oyster reefs. During the summer 2001, we conducted intertidal surveys to determine the
abundance of H. sanguineus and a sympatric native mud crab (Dyspanopeus sayi) at seven (mud/rock) sites within
the Hudson River estuary. During low tide, both crab species retreat under similar sized rocks (400-600cm2) with
densities of 1 to 4 individuals per rock, either in single or mixed species groups. Based upon field distributions, we
designed laboratory experiments to offer juvenile Crassostrea virginica (5-20mm length) to H. sanguineus
(carapace width = 17.72.7mm) and D. sayi (c.w. = 18.43.2mm) in single or mixed species groups at either low (2
crabs/enclosure cage) or high density (4/cage). All predator trials were conducted in flow-through enclosure cages
(25x20cm) within a 700L re-circulating seawater system and replicated 10 times. During 1h trials, we evaluated
crab per capita consumption rates by oyster size, crab species and predator density. In trials with only two crabs per
cage, we found no consistent differences among prey size, predator species, or crab interspecific interactions on
oyster consumption rates (ANOVA, all p’s > 0.05). However, at a higher predator density, a significant prey size by
crab species interaction developed (ANOVA, F3,143=4.284, p=0.006). Under these conditions, Hemigrapsus tended
to select smaller oyster sizes, while Dyspanopeus ate larger oysters. This study suggests that size-specific predation
risk to oysters results from a non-linear interaction between predator species and density and may not be directly
inferred from single species trials conducted at low density.
The influence of temperature on activity and density relative to catch per unit effort in lobster traps
Steve Jury,* Walter Golet, Hunt Howell, and Win Watson. *Biology Department, SUNY New Paltz, New Paltz, NY
12561, USA; jurys@newpaltz.edu; Zoology Department and Center for Marine Biology, UNH, Durham, New
Hampshire, USA 03824, USA; e-mail whw@cisunix.unh.edu, whh@christa.unh.edu.
It is widely accepted that catch per unit effort generally increases with increasing temperature primarily due to
increases in activity (based on a seminal study by McLeese and Wilder in 1958). However, the role of temperature
effects on catch has remained controversial. Increased activity could increase catchability by increasing 1) the
probability of finding a trap and 2) the probability of entering that trap. However habitat selection for preferred
temperatures may also increase the density of lobsters moving into a given area and thus increased density may
ultimately lead to increased catch. Temperature may have effects on other factors as well including feeding
behavior, satiation, probability of exit from a trap, and the probability of lobsters in a given fishing area molting into
a ‘trappable’ size. All of these factors could be influencing ultimate catch per unit effort at a given temperature.
Based upon lab and field assessments of activity at seasonal temperatures, assessment of behaviors in and around
traps using an in situ video monitoring system, (Lobster Trap Video-LTV), trapping studies, and SCUBA seasonal
assessments of lobster densities we are gaining an understanding of the relationship between seasonal changes in
temperature and the subsequent effects on catchability. Our data and a review of the literature suggest that while
temperature affects both activity and density, catch is only temperature dependent at low temperatures while it is
relatively temperature independent at higher temperatures.
Examining the effects of Dictyota epiphytism and secondary chemicals on neighboring reef biota using
Halimeda tuna as a model organism
A. Kahn,1* K. Beach,1 H. Borgeas,1 and L. Walters.2 1University of Tampa, Tampa, Florida 33606, USA;
2
University of Central Florida, Orlando, Florida 32816 USA, USA.
Since 1994, the phaeophyte Dictyota spp. has spread to cover as much as 70% of the benthic community at certain
reef sites in the Florida Keys. Dictyota grows both saxicolously and epiphytically on numerous reef organisms.
Beyond occupying space, it is unclear what impacts this macroalga is having on the reefs when in high abundance.
The possible impacts such a high algal cover may have on epiphytized as well as neighboring benthic organisms
were examined using the chlorophyte Halimeda tuna as a model. The growth rate and physiology of H. tuna were
examined for both naturally epiphytized and unepiphytized individuals. The relationship between Dictyota and H.
tuna was further elucidated by exploring the effects of the secondary chemicals leached from Dictyota into the
surrounding seawater and onto epiphytized as well as around neighboring H. tuna. The presence of epiphytic
Dictyota on H. tuna was found to decrease Pmax and growth rates as well increase levels of photosynthetic
accessory pigments in epiphytized individuals. Such changes were consistent with the impact of shading by the
epiphyte on H. tuna. Increased Rd was also observed in epiphytized H. tuna as well as unepiphytized H. tuna
individuals exposed to Dictyota-conditioned water. Elevated respiration rates were inconsistent with the
physiological impact of shading. In situ, no significant impacts were observed on the growth rate or physiology of
unepiphytized H. tuna when neighboring Dictyota cover was experimentally increased on the reef. In conclusion,
the spread of Dictyota over reefs in the Florida Keys impacts reef system by occupying space, shading, overgrowing
organisms and negatively impacting metabolic processes of epiphytized hosts when the secondary metabolites from
Dictyota reach high enough concentrations.
Monitoring changes in the fully protected zones of the Florida Keys National Marine Sanctuary
Brian D. Keller.* Florida Keys National Marine Sanctuary, P.O. Box 500368, Marathon, FL 33050, USA; e-mail
brian.keller@noaa.gov.
The Florida Keys National Marine Sanctuary is a 9,850 km2 marine protected area managed by the U.S. National
Oceanic and Atmospheric Administration and the State of Florida. A comprehensive management plan was
implemented in 1997 to protect and conserve marine resources of the Florida Keys. One aspect of the management
plan is the creation of a network of 24 fully protected zones (marine reserves). An ongoing monitoring program is
designed to determine effects of “no-take” protection on heavily exploited fishes and invertebrates, benthic
communities, and human activities. Data on the abundance and size of fish, spiny lobster, and queen conch; algal
cover; coral cover, diversity, and recruitment; and zone usage are collected from fully protected zones and adjacent
reference sites. Preliminary reports indicate increases within the fully protected zones in the number and size of
heavily exploited species such as spiny lobster and certain reef fishes. Slower-growing benthic species such as
corals and sponges have not shown significant changes within fully protected zones, possibly because the zoning
plan was implemented less than five years ago.
The relationship between surface water nutrients, seagrasses and their associated epiphytes along Florida’s
central gulf coast
Stephanie R. Keller,* Jaime M. Greenawalt, and Thomas K. Frazer. University of Florida, Department of Fisheries
and Aquatic Sciences, 79222 NW 71st Street, Gainesville, Florida 32653, USA.
Seagrass coverage along Florida’s central Gulf coast is extensive. In fact, seagrass beds are often the dominant
structural feature in the shallow coastal waters of the region. As such, seagrasses provide important refuge and
forage habitats for a myriad of ecologically and economically important fauna. Approximately 85% of the exploited
fishery species in Florida spend some portion of their life history in estuaries, and many of these are considered
obligate seagrass inhabitants. Thus, seagrass beds are considered essential to the ecological integrity and health of
Florida’s estuarine and nearshore coastal ecosystems. However, seagrass beds along the central Gulf coast of
Florida are potentially threatened by increasing nutrient inputs. Such inputs can lead to increases in phytoplankton,
macroalgae and epiphytic growth on seagrass blades, which reduce light availability and may decrease seagrass
productivity. In extreme cases, extensive mortality of seagrass beds may occur with a concomitant shift in trophic
structure and ecosystem function.
As part of an effort to understand the course of such changes, we described the relationship between surface water
nutrient concentrations and epiphyte abundance on seagrasses over a broad and representative area of the central
Gulf coast of Florida (from the Weeki Wachee River north to the Waccasassa River). A latitudinal gradient in
nutrient (phosphorus) concentrations had previously been documented in this area. As predicted, epiphytes were
most abundant on seagrasses in the northern portion of the study area where surface water phosphorus
concentrations were also highest. Preliminary results from a nutrient enrichment experiment carried out in the
southern portion of the study area suggest that further increases in phosphorus will stimulate epiphytic growth on
seagrass blades.
Do more oyster larvae settle in rough neighborhoods?: The influence of small-scale topography on oyster
recruitment
M. Lisa Kellogg* and Rita B. J. Peachey. Dauphin Island Sea Lab, 101 Bienville Blvd., Dauphin Island, AL 36528,
USA, and Department of Marine Sciences, LSCB 25, Univ. of South Alabama, Mobile, AL 36688, USA.
A series of field surveys, laboratory experiments and field experiments were used to determine if differences
between natural oyster reefs and shell plantings in Mobile Bay, Alabama affect the recruitment rates of oyster
larvae. Analysis of field surveys indicated that natural oyster reefs and shell plantings differ in their topographic
complexity, shell orientation, and shell size distributions. ADV measurements taken over the two types of reefs
demonstrate that natural reef topographies produce more turbulence and create thicker boundary layers than shell
planting topographies. Differences in reef topography and local hydrodynamic regime have the potential to affect
the delivery rates of particles such as oyster larvae to the surface of a reef from the overlying water column. To
determine if more of the larvae passing over a reef are retained within the matrix of natural reefs, single-pass
experiments were conducted using eyed pediveliger oyster larvae released upstream of the two reef types in a
racetrack flume. Analysis of substratum samples indicated that more larvae were found within the matrix of natural
oyster reef treatments than within shell planting treatments. Field studies of recruitment rates demonstrated that
significantly more oyster larvae recruit to natural reef topography treatments. Thus, our studies indicate that the
small-scale topography (1-30 cm) of oyster reefs can affect the rate of oyster recruitment. We believe that the
increased rates of recruitment to natural reef topographies are due, at least in part, to a local hydrodynamic regime
that favors the deposition of particles such as oyster larvae.
Influence of secondary metabolites from Caribbean sponges on bacterial surface colonization
Sarah R. Kelly* and Joseph R. Pawlik. Biological Sciences and Center for Marine Science, University of North
Carolina at Wilmington, Wilmington, NC, USA.
Organic extracts from 8 Caribbean sponges were assayed for inhibitory effects on surface colonization of twentyfour marine bacterial isolates, four known marine invertebrate pathogens, and a common fouling bacterium. Each
extract was tested for inhibition of bacterial attachment, growth and swarming. The 24 bacterial strains were
isolated from the surfaces of the sponges, nearby substrata, or the surrounding seawater. Extracts from sponge
species inhibited bacterial attachment. Sponge extracts had a minimal effect on growth, with only 5 sponges
affecting a total of 6 strains. Twelve strains were inhibited from swarming by 4 sponge extracts. Overall the
chemical effects of bacterial colonization by sponges may target attachment and be complemented by swarming and
growth inhibition. This investigation presents evidence that non-toxic metabolites may influence bacterial epibiosis
on the surfaces of marine sponges.
Ecological consequences of El-Niño Southern Oscillation to coral reef Foraminifera
F. Kelmo1,2* and M. Attrill.1 1Benthic Ecology Research Group, Plymouth Environmental Research Centre,
Department of Biological Sciences, University of Plymouth, United Kingdom; 2Brazilian Research Council—
Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, CNPq—Brazil.
Reef-dwelling Foraminifera hold substantial potential as indicators of reef vitality. Although this group has been
heavily investigated to date, most of the environmental studies have focused on rapid-assessment of anthropogenic
stress. Such short-term investigations may be highly suitable for diagnosing acute impacts on very well-known reef
systems (where they comprise limited sample sizes and a minimal number of species). However, their use has not
been validated for assessing the long-term consequences of natural disturbances. We have undertaken a long-term
investigation in order to verify any response of these organisms to a major, defined environmental disturbance, the
1997-1998 El-Nino Southern Oscillation (ENSO). In this paper we present the first quantitative results of a six years
study which investigates variations in shallow water foraminiferan community composition from 1995 to 2000.
Sediment samples were collected with a 50g core, annually, at four reef sites from Northern Bahia (Brazil) and all
foraminiferans were extracted and identified. A total of 285 species were recorded from the area, including 26
species new to science. The densities of live-forams were significantly different (ANOVA, F=56.762, P<0.001)
between pre- and post-ENSO years, and multivariate analysis suggested dramatic changes in community
composition. BIOENV analysis identified mean temperature variance and UVR incidence as the main factors best
explaining changes in the community, stress factors associated with the ENSO. Whilst ENSO appeared to have an
overall detrimental impact on the foraminiferan community (in terms of total diversity and abundance), the
disturbance has resulted in influx of several new species previously unrecorded in the survey.
Anti-predation strategies in marine worms: to hide or be distasteful, that is the question
C. E. Kicklighter* and M. E. Hay. Georgia Institute of Technology, Atlanta, GA, USA; e-mail
gt7853a@prism.gatech.edu, mark.hay@biology.gatech.edu.
Chemical defenses are important predator deterrents for many organisms inhabiting predator-rich enviornments.
While chemical, structural, and nutritional defenses against consumers are well studied for sessile species such as
seaweeds and sponges, how a chemical defense may be used with other anti-predation strategies, such as behavioral
avoidance and refuge use, has not been adequately addressed. To investigate this question, marine worms were
examined for palatability to sympatric predators. Chemical traits, behavior, and refuge use were examined for the
role they play in determining palatability and susceptibility to consumers. Our findings suggest that species exposed
to predators are unpalatable and chemically defended, while species that utilize a spatial or structural refuge are
more palatable. Moreover, for some refuging species, body parts that remain in a strong tube are palatable and lack
deterrents while those in a weak tube are unpalatable. Regardless of tube strength, more exposed or more
nutritionally rich body parts are more unpalatable and possess chemical or structural deterrents. Behavior is also an
important anti-predation strategy. When contrasting palatable with unpalatable species that live in tubes, palatable
species retract more quickly and completely into a tube and do so at a greater distance from a physical disturbance.
These patterns suggest that (1) deterrent strategies vary with refuge use, refuge strength, and are allocated to body
parts that are more nutritious or more likely to encounter predation and (2) there is variability in the use of
avoidance versus deterrence strategies within a taxonomic group.
Intra-year class cannibalism in early juvenile blue crabs
Deborah A. Kilbane* and Ken Heck. University of South Alabama and Dauphin Island Sea Lab, Dauphin Island,
AL 36528, USA.
Intra-year class cannibalism among juveniles significantly influences the density of several crab species. This study
tests the hypothesis that intra-specific predation on recently settled blue crabs (Callinectes sapidus) is a primary
controller of the density of juvenile blue crabs. Preliminary work to determine which sizes of intra-year class
juveniles are able to consume new settlers and whether cannibalism is density dependent. I have found that
cannibalistic mortality rates increase with increasing conspecific predator carapace width and increasing settler
densities. This work will continue both in the field and in the lab to further determine the role that cannibalism
plays in regulating the abundance of juvenile blue crabs.
Fundulus majalis as a potential predator of the invasive asian shore crab Hemigrapsus sanguineus
A. K. Kim and N. J. O’Connor.* Department of Biology and School for Marine Science and Technology, University
of Massachusetts Dartmouth, No. Dartmouth, MA 02747-2300, USA.
In the rocky intertidal zone of the east coast of the United States, Hemigrapsus sanguineus is a successful recent
invader whose ecological impacts are little known. For example, predators of H. sanguineus have not been well
identified. One potential predator of H. sanguineus is the striped killifish, Fundulus majalis, an opportunistic
bottom feeder on sandy and pebbly substrates whose diet includes crustaceans. Laboratory experiments were
performed with and without a natural substrate (sand and rocks) to determine the ability of F. majalis to consume
megalopae (postlarvae) and juvenile H. sanguineus. Results demonstrate that F. majalis can consume H. sanguineus
megalopae and first stage crabs, but crabs ≥ 3 mm in carapace width were rarely consumed. Although fewer firststage crabs were consumed when substrate was present, megalopae were eaten in large numbers regardless of
substrate. There was little difference in consumption rates by male and female F. majalis from 60 to > 100 mm total
length. F. majalis might prey on settling megalopae and small juvenile H. sanguineus in the field, but crabs likely
escape predation by killifish at relatively small sizes.
Biomass of invertebrates in mussel beds at hydrothermal vents and cold seeps
K. Knick,* C. Jenkins, M. Doerries, S. Rapoport, E. Raulfs, J. Salerno, M. Turnipseed, M. Ward, and C. L. Van
Dover. Department of Biology, College of William and Mary, Williamsburg, VA 23187, USA; e-mail
Keknick@yahoo.com.
Hydrothermal vents and cold seeps are both chemosynthetic ecosystems, but they vary in resource availability, fluid
chemistry, temperature, age, and other environmental features. These characteristics seem likely to influence
ecological measures such as biomass, but patterns of distribution of biomass at vents and seeps are poorly known. In
this study, we compared the biovolume of macrofaunal invertebrates associated with mussels beds at three sites
along the Northern East Pacific Rise, three sites along the Southern East Pacific Rise, and at the Florida Escarpment,
Gulf of Mexico cold seep. Mussel beds occur globally at vents and seeps and have shallow-water analogs, so they
are useful habitats for comparative studies of biomass. There was no significant difference in biovolume among
active sites. Biovolume of mussel beds was relatively lower at a dying site on the Southern East Pacific Rise. There
was greater variation of biovolume within sites than between sites, indicating a local heterogeneity. Distribution of
biovolume among major taxa varied among sites, and 1 or 2 species typically accounted for greater than 60 % of the
total biovolume of invertebrates within mussel beds. These species also tended to be the numerical dominants. We
conclude that even though vents and seeps are different ecological systems, they produce comparable amounts of
invertebrate biomass within mussel beds.
Effects of seagrass shoot dynamics on distribution and recruitment of epifaunal encrusting bryozoa
N. Kouchi,1* M. Nakaoka,2 and H. Mukai.1 1Akkeshi Marine Station, Hokkaido University, Aikappu, Akkeshi-cho,
Akkeshi-gun, Hokkaido 088-1113, Japan; 2Graduate School of Science and Technology, Chiba University, Yayoicho 1-33, Inage, Chiba 263-8522, Japan.
Sessile invertebrates are one of the important components of seagrass community. Seagrass leaves are ephemeral
habitats, and their dynamics may affect the distribution of epifauna living on them. Zostera caulescens is remarkable
in a point that it forms a high canopy (5–7 m from the sea bottom) composed of flowering shoots. It, thus provided
the habitat for epifauna with the wide range of height in the water column. We studied distribution and recruitment
pattern of encrusting bryozoa Microporella trigonellata, most abundant epifauna on Z. caulescens in Funakoshi Bay,
northeastern Japan, by monthly field sampling. We also constructed field experiments to determine the effects of
seagrass shoot type (flowering and vegetative shoots) and the position in the water column (high and low) on the
bryozoan recruitment.
Bryozoan density on the flowering shoots varied seasonally, reaching maximum in summer and low in winter. In
contrast, it was constant and low on the vegetative shoots through a study period. The variation in the bryozoan
density well coincided with that of early recruited colonies, and thus the recruitment process was important to
determine their distribution. Field experiments showed that the recruitment rate of M. trigonellata was significantly
higher at the higher position in summer season, however, this site selection was not observed in autumn when the
most of the flowering shoots fell down. The seasonal change in habitat selection by bryozoan was considered to be
adaptive to maintain their population on the seagrass leaves that show seasonal dynamics.
Population age structure as a record of recruitment history: How large a grain of salt do we need?
Jacob P. Kritzer* and Peter F. Sale. Department of Biological Sciences, University of Windsor, Windsor, Ontario
N9B 3P4 Canada.
Information on spatial and temporal patterns in recruitment of coral reef fishes is central to addressing a range of
ecological questions. Unfortunately, unlike commercially important species in northern temperate waters, extensive
time series of recruitment are lacking for tropical reef fishes. Several researchers have suggested that a snapshot
sample of a population age structure will illustrate the relative strength of different year classes and, therefore, can
serve as a proxy for recruitment history in the absence of explicit recruitment data. However, this approach has been
criticized on the basis that post-settlement demography subject to temporal variability, density dependence or a
combination of both can obscure the link between initial recruitment and cohort strength at a later time. This
criticism suggests that recruitment information stored within an age structure must at best be taken with a grain of
salt. We use computer simulations to evaluate how large this grain of salt must be. Each simulation spanned 20
years of population dynamics of a hypothetical reef fish species. A new cohort of variable size recruited to the
population at the start of each year, and was then modified in each subsequent year first by juvenile mortality rates
and then by adult mortality rates. Distinct simulations incorporated different combinations of underlying ecological
assumptions about variable recruitment (normally versus log-normally distributed) and post-settlement demography
(density-dependent versus density-independent). The age structure at the end of each simulation was compared with
the known history of recruitment to assess their similarity. Our study suggests the relative importance of the factors
that can negate the link between recruitment and subsequent age structure. Our study also highlights the importance
of continued empirical research on the modification of recruitment strength through time in order to best exploit the
information potential of population age structures.
More bang for your buck: multiple defensive roles of sponge triterpene glycosides
Julia Kubanek,1* Kristen E. Whalen,2 Sebastian Engel,2 Sarah R. Kelly,2 Timothy P. Henkel,2 William Fenical,3 and
Joseph R. Pawlik.2 1Georgia Institute of Technology, School of Biology, Atlanta, GA 30332-0230, USA; 2University of
North Carolina at Wilmington, Center for Marine Science, Wilmington, NC 28403, USA; 3Scripps Institution of
Oceanography, Center for Marine Biotechnology and Biomedicine, La Jolla, CA 92037-0204, USA.
Despite high nutritional value and a lack of physical defenses, most marine sponges appear to be minimally affected by
predators, competitors, and fouling organisms, possibly due to sponge chemical defenses. In the last fifteen years,
several triterpene glycosides have been isolated from sponges, but their ecological or physiological roles are largely
unknown. We tested triterpene glycosides from Erylus formosus and Ectyoplasia ferox, Caribbean sponges belonging to
two different orders, in field and laboratory assays for effects on fish feeding, attachment by potential biofilm-forming
bacteria, fouling by invertebrates and algae, and overgrowth by neighboring sponges. Formoside and other triterpene
glycosides from Erylus formosus deterred predation, microbial attachment, and fouling by invertebrates and algae.
Triterpene glycosides from Ectyoplasia ferox were found to be antipredatory and allelopathic. Thus, triterpene
glycosides in these sponges appear to have multiple ecological functions. Tests with different triterpene glycosides at
several concentrations indicated that small differences in molecular structure affect ecological activity.
Getting over the hump: barriers to dispersal and the northward spread of asexual populations of the genus
Mastocarpus in the Atlantic and Pacific
Janet Kübler and Steve Dudgeon. Department of Biology, California State University, Northridge, CA 91330-8303,
USA.
It is often assumed that asexual populations, being free of the need to find mates, can disperse farther and faster than
sexually reproducing populations. One would expect this pattern to be even more pronounced for taxa with
heteromorphic alternation of generations that include a slow-growing crustose phase in the sexual life cycle.
Difference in the rate of postglacial recolonization of the temperate north after the last ice age might, hypothetically
explain the more northerly distributions of asexual populations in numerous taxa. If asexual populations could
recolonize the north more quickly, the appearance of a geographic barrier to dispersal during recolonization should
be reflected in their current distributions. We use existing and new data for the geographic distributions of sexual
and asexual variants of Mastocarpus papillatus in the Pacific and Mastocarpus stellatus in the Atlantic to test this
hypothesis. We used logistic regression to determine where along their respective coasts mixed populations switch
from predominantly one life history type to the other. In the case of M.papillatus, the outflow of freshwater into the
Pacific from San Francisco Bay may be a recent dispersal barrier. Similarly, the English Channel may inhibit
northward dispersal of M. stellatus from the Atlantic coast of Iberia to the British Isles.
Physiology in the field: large and small-scale gradients of photosynthetic performance in fucoid algae
M. Lamote,1,2 Y. Lemoine,2 and L. E. Johnson.1* 1G.I.R.O.Q., Université Laval, Québec, G1K 7P4, Canada;
2
Laboratoire de cytophysiologie végétale et Phycologie, Université de Lille I, 59575 Villeneuve d’Ascq, France.
Physical conditions experienced during low tide may affect the performance of intertidal algae thereby contributing
to their patterns of distribution. Québec rocky shores are dominated by three fucoid algae Ascophyllum nodosum,
Fucus vesiculosus, Fucus distichus, which can form distinct zones. We investigated the photosynthetic activity of
various stages of these algae as measured by pulse-amplitude modulated (PAM) fluorometry under a variety of
different meteorological regimes, including the sunny and windy conditions that exacerbate thallus dehydration. For
adult plants, photosynthesis continued for several hours after emersion before photoinhibition (i.e., reduced
photosynthetic efficiency, Fv/Fm) was observed. Differences among species corresponded with their position on the
shore with adults of the lowest distributed species, F. distichus, showing the quickest and most dramatic evidence of
photoinhibition, especially under sunny-windy conditions. Early stages (3 wk-old) of all species responded more
quickly than adult stages, and no differences were seen among the different species, suggesting possible ontogenetic
shifts in their response to environmental conditions. More fine-scale measurements on F. distichus showed that
photosynthesis is highly sensitive to vertical position on the shore and appears to be determined by rates of
evaporation. Because desiccation is controlled by environmental conditions, differences in recruitment observed
between different tidal heights and different years may depend on the variation in the frequency, timing, and
duration of particularly stressful meteorological conditions that reduce growth and survival.
An ecophysiological approach to understanding patterns of nitrate reduction
in estuarine macroalgae
Julien Lartigue1* and Tim D Sherman.2 1University of South Alabama, Department of Marine Sciences; LSCB-25,
Mobile, Alabama 36688-0002, USA, and Dauphin Island Sea Lab, 101 Bienville Blvd, Dauphin Island, AL 36528,
USA; 2University of South Alabama, Department of Biological Sciences, LSCB-124, Mobile, Alabama 36688-0002,
USA.
In estuaries, freshwater input can lead to substantial changes in the amount and form of inorganic nitrogen available
to macroalgae. Whether macroalgae are able to translate this pulsed supply of inorganic nitrogen, especially nitrate,
into production depends on how quickly rates of nitrate assimilation can be increased. In turn, the assimilation of
nitrate is rate-limited by the reduction of nitrate to nitrite by the enzyme nitrate reductase (NR). A novel NR activity
assay developed for use in the laboratory and field was employed to determine if Enteromorpha sp. (Chlorophyceae)
and Gelidium sp. (Rhodophyceae) from Mobile Bay, AL are able to access pulses of nitrate entering the estuary.
Seasonal field measurements demonstrated that NR activity increases as much as 3-fold following pulses of less
saline, nitrate-rich water. However, other environmental factors, including temperature and light, were also
significant predictors of NR activity. Surprisingly, NR activity was not completely inhibited in the presence of
appreciable amounts of ammonium, although NR activity and ammonium had a significant negative correlation.
Physiological factors, such as internal nutrient stores and protein levels, were not correlated to NR activity.
Laboratory experiments on Enteromorpha sp. demonstrated that NR activity begins to increase when nitrate
becomes available and peaks after approximately 3 hr, while nitrate uptake rates slowly decline as internal stores of
nitrate increase. Following nitrate pulses, NR activity remains elevated for at least 12 hr, even in nitrate-depleted
waters. To date, this work indicates that estuarine Enteromorpha sp. and Gelidium sp. are able to take up and reduce
nitrate when delivered in pulses. Furthermore, external, environmental factors (i.e. water column nutrients), rather
than internal, physiological factors (i.e. internal nutrient stores) are more influential in determining rates of nitrate
reduction.
Fertilization success on a surface brooding gorgonian
Howard R. Lasker.* Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA.
In the Bahamas, the Caribbean gorgonian Pseudopterogorgia elisabethae spawns during 3-5 day periods after the
new moon during November and December. Female colonies release eggs that remain on the surface of the colony.
Eggs are fertilized on the surface, develop over several days after which time the planulae are washed off by wave
and current action. Male spawning has not been directly observed. Among other surface brooding species distance
between males and females can be a critical factor affecting the successful fertilization of released eggs and low
fertilization rates have been observed in nature. However, fertilization among P. elisabethae eggs was high during
spawning in December 2001 regardless of local colony density. Eggs were collected from 18 different P.
elisabethae colonies on San Salvador Is. in the Bahamas and inspected for signs of development as an assay of
fertilization. Over the 5 days that spawning was observed, 88% of the 15,214 collected eggs had initiated
development. Fertilization success was lowest on the first and last days of spawning but even on those days was
sometimes greater than 50%. Eggs collected from different colonies had differing levels of fertilization success but
that pattern best correlates with which days the colony spawned. There was no apparent relationship between
fertilization rate and local (with 2 m) population density. One of the highest fertilization rates occurred on a colony
that only had 3 other colonies within 2 m and all three were over 1 m away from the colony. Male density
ultimately will have some affect on fertilization rates, but at the densities found on San Salvador close proximity
was not required to assure fertilization.
Behavior of grouped spiny lobsters, Palinurus argus, under attack by piscine predators, Balistes capriscus
Kari L. Lavalli,1* William F. Herrnkind,2 Michael Childress,3 and Andrew Evans.1 1Department of Biology,
Southwest Texas State University, 601 University Drive, San Marcos, TX 78666, USA; 2Department of Biological
Science, Florida State University, Tallahassee, FL 32306-1100, USA; 3Department of Biological Sciences, Clemson
University, Clemson, South Carolina 29634, USA.
Mesocosm experiments at the Keys Marine Laboratory were performed to investigate the effects of predatory
triggerfish, Balistes capriscus, on the grouping and defensive behavior of free-roaming spiny lobsters, Panulirus
argus in 2000. Lobsters in groups of 1, 3, 5, 10, and 20 were exposed to 5 triggerfish after acclimation to mesocosm
conditions for 1-2 hours. Group sizes were observed every 5 min for 3 hours. Lobsters showed a bimodal
distribution in group size and were found commonly as either 1-3 individuals or >3, >7, and >15 individuals for 5,
10, and 20 lobsters, respectively. Examination of distributions per hour revealed that lobsters formed fewer large
groups initially, but coalesced into larger groups as the number of fish attacks increased over time. The point at
which an individual lobster was subdued and killed influenced the overall pattern of group size distributions, such
that larger groups were formed shortly after the death of a lobster. These results indicate that (a) predator presence
strongly influences the development of lobster defensive rosettes, and (b) increased exposure to attacking fish drives
the development of larger and larger rosettes of lobsters. Behavioral interactions were also videotaped and scored to
determine the type and frequency of lobster counter-attack measures during fish attacks. The behavioral data was
further analyzed to determine frequency differences between attack countermeasures by single lobsters and by
individual lobsters remaining within a group. These data will be discussed with regard to the benefits of group
living.
Spatial displacement of the snail Melampus bidentatus by a sympatric salt marsh snail
Sarah Lee* and Brian Silliman. Department of Ecology and Evolutionary Biology, Brown University, Providence,
RI 02912, USA.
The role that biotic interactions such as competition and habitat amelioration play in structuring salt marsh plant
communities has been the subject of much exploration. Few studies, however, have examined the importance of
interspecific interactions in determining the distribution of salt marsh animals. Here, we examined the possibility
that the distribution of the snail Melampus bidentatus in salt marshes on Sapelo Island, Georgia, was limited by
direct (i.e., competition) or indirect (through habitat alteration) interactions with another abundant gastropod,
Littoraria irrorata. Cages were used to determine the effects of shading and Littoraria densities on the abundance of
Melampus. Choice experiments were conducted in the lab to ascertain whether Melampus avoided cues present in
Littoraria mucus. Under natural conditions, both snails were rare in the low marsh, with Littoraria and Melampus
dominating middle and high marsh, respectively. In the middle marsh, removal of Littoraria and light reduction
significantly increased densities of Melampus. Adding Littoraria in the high marsh significantly decreased
Melampus densities, and the choice experiment demonstrated that Melampus used mucus cues to avoid Littoraria.
Although Littoraria clearly are not the only determinants of of Melampus distribution, our results suggest that
Melampus avoid high densities of Littoraria. This behavior is likely evoked by both a reduction in the shade canopy
due to Littoraria grazing and by cues present in Littoraria mucus. These preliminary analyses suggest that
interspecific interactions play an important role in structuring the macroinvertebrate community in these marshes.
Crab predation prevents the successful reestablishment of sea urchins in Maine
Amanda V. Leland* and Robert S. Steneck. University of Maine, Darling Marine Center, 193 Clark’s Cove Rd.,
Walpole, ME 04573, USA.
Green sea urchins (Strongylocentrotus droebachiensis) have been extirpated by overfishing in vast areas of the Gulf
of Maine over the last 15 years. We examined the hypothesis that the reintroduction of adult urchins can aid in
population recovery. In two separate trials (August 2000 and April/May 2001), we relocated 3000 adult urchins to
each of 9 sites in an area where urchins were once abundant but are now depleted. In both trials, urchin abundance
declined dramatically in the latter part of August and early part of September, when large migratory crabs (Cancer
borealis) invaded the area. These crabs were significantly larger and more abundant at all relocation sites in August
and September 2001 than they had been prior to or after that period. In addition, crabs were significantly more
abundant at urchin relocation sites than control sites during this time suggesting that crab predators were actively
seeking urchin prey. We propose that serial overfishing of multiple trophic levels in coastal Maine may have
relaxed crab population controls so that they may maintain this system free of herbivores.
Analysis of genetic variation in mtMSH in the genus Leptogorgia (Cnidaria: Octocorallia) and implications
for studying population structure
Andrea LePard* and Scott C. France. Department of Biology, University of Charleston, SC, Charleston, SC, USA.
The mitochondrial genome is often used in analyses of genetic structure because of its usefulness at a variety of
taxonomic levels. Previous studies of octocorals have shown little intraspecific variation within the mitochondrial
genome. However, mtMSH (mitochondrial MutS homolog, a putative mismatch repair gene), a marker unique to
octocorals, has shown relatively high-levels of variation between species. The objectives of this study are to
determine if mtMSH will be a variable marker on the intraspecific level. To test this hypothesis, we analyzed
mtMSH DNA sequences of the octocoral Leptogorgia virgulata from the U.S. east and Gulf coasts, which we
expected would be divided into subpopulations due to isolation by distance.
We have sequenced the entire mtMSH gene (≈3000 bp) in Leptogorgia virgulata, L. hebes, and L. chilensis. We
have found little variation within the genus and no intraspecific variation in mtMSH within these three species. We
also sequenced the non-coding region (NCR) between COI and COII and found the same result. Lack of
intraspecific variation within the sequenced mitochondrial DNA regions could be a result of several processes. If
the product of mtMSH is functional in mismatch repair, it would lower mutation rate in mitochondrial DNA, which
would eliminate possible variation. High levels of gene flow between populations would also account for low
variation. We are now looking at nuclear gene regions to evaluate these alternate hypotheses.
Can trophic interactions drive salt marsh succession? Using restoration and invasion research to untangle
the trophic web
L. Levin,1* T. Talley,1 P. McMillan,1 C. Neira,1 G. Mendoza,1 S. Moseman,1 C. Forder,1 C. Whitcraft,1 C. Currin,2
R. Michener.3 1Integrative Oceanography Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0218,
USA; 2National Ocean Service, 101 Pivers Island Road, Beaufort, NC 28516, USA; 3Boston University Stable
Isotope Lab, Department of Biology, 5 Cummington St., Boston, MA 02215, USA.
Fundamental interest in maintaining healthy wetlands has focused attention on ecosystem function. The key salt
marsh trophic support functions appear straightforward, but detailed trophic webs are difficult to infer when one
cannot determine what organisms are assimilating. We employed direct gut content observations, natural abundance
stable isotopic analyses, and C-13 tracer studies to evaluate macrofaunal successional shifts in faunal trophic
structure as vascular vegetation cover developed in a created Spartina foliosa marsh in Mission Bay, California.
Results from this and related studies suggest that bottom-up processes (changing microalgae/detritus availabilities)
generate transitions in marsh macrofauna from insect-dominated to annelid-dominated communities in the restored
marshes of southern California. Spartina (alterniflora-foliosa) hybrid invasion on unvegetated tidal flat habitat in
San Francisco Bay appears to drive a similar successional scenario, but with different macrofaunal players. These
studies exemplify the potential for invasion and restoration sites to provide large-scale "experiments" that elucidate
determinants of wetland structure and function.
Reproductive isolation among the Montastraea annularis species complex
Don R. Levitan1* and Nancy Knowlton.2 1Department of Biological Science, Florida State University, Tallahassee,
FL 32306-1100; e-mail levitan@bio.fsu.edu; 2Marine Biology Research Division, Scripps Institution of
Oceanography, La Jolla, CA 92093; e-mail nknowlton@ucsd.edu.
There is an ongoing discussion on the nature of species and speciation in corals. Many coral species spawn
simultaneously, have compatible gametes, and perhaps hybridize intermittently. Three western Atlantic corals,
Montastraea annularis, M. faveolata, and M. franksi all spawn sympatrically on the same evenings after the full
moons of late summer and early fall. There has been a controversy as to whether these taxa are truly different
species and in particular, given their pattern of spawning, whether they are reproductively isolated. Here we report
on laboratory studies of gamete compatibility and field studies of spawning times, gamete dispersal, and fertilization
success in both Panama and the Bahamas over multiple years. The results indicate that temporal differences in
spawning, sperm aging, egg dispersal, and gametic incompatibility act in various combinations among the three
species to render hybrid fertilization unlikely.
Distribution of Tritonia sp., a tritoniid opisthobranch, on a Bahamian patch reef
Cynthia L. Lewis,* Meredith A. Dorner,* and Evelyn Luna. Buffalo Undersea Reef Research, Department of
Biological Sciences, State University of New York at Buffalo, Buffalo, NY, 14260, USA; telephone (716) 645-2178.
Small tritoniid opisthobranchs, probably Tritonia hamnerorum, were observed on both Gorgonia flabellum and G.
ventalina along the seaward portion of a patch reef off Rocky Point, San Salvador, Bahamas. Although both the
gorgonian species and the nudibranchs were clumped, the gorgonians were distributed around the reef while the
nudibranchs were observed only on the seaward side of the reef. G. ventalina colonies were significantly larger and
more abundant than G. flabellum. Nudibranchs showed no significant preference for one species of gorgonian over
the other based on either the number of colonies or total surface area of the gorgonians in the transects where the
nudibranchs were observed. Nudibranchs were only observed on colonies with a surface area smaller than 0.35 m2.
Among colonies containing Tritonia, no relationship was found between the size of the gorgonian and the number of
tritoniid nudibranchs present. The number of tritoniid nudibranchs observed on individual sea fans varied between
two consecutive days.
Patterns of benthic community structure and differential recruitment in Narragansett Bay, Rhode Island
(USA)
Emily L. Lindsey,* Andrew H. Altieri, and Jon D. Witman. Department of Ecology and Evolutionary Biology,
Brown University, Providence, RI 02912, USA.
Preliminary research has revealed distinctive patterns in the faunal composition of benthic communities in
Narragansett Bay, RI, and suggests that differences in recruitment of benthic snails (Crepidula plana and C.
fornicata) and mud crabs (Dispanopeus [Neopanope texana] sayi) correlates with the presence of blue mussel
(Mytilus edulis) beds. The large-scale Mytilus recruitment in spring 2000 allowed us to test the hypothesis that
predator (D. sayi) recruitment tracks prey density in this system. Crepidula and Dispanopeus recruits were collected
on settlement brushes at eight subtidal (4m -5m MLW) sites in Narragansett Bay. The study sites were
distinguished by flow regime. Presence of Mytilus was assumed to correlate positively with flow. “Low flow” sites
had 0%-0.13% live mussel cover. “High flow” sites had 17%-61% live mussel cover. Crepidula densities were
nearly ten times higher on average at sites where mussels were absent. Average densities of mud crab recruits were
more than twice as high at sites where mussels were absent. These results indicate that recruitment of Dispanopeus
sayi correlates positively with Crepidula recruitment and inversely with the presence of Mytilus edulis and/or flow
intensity, and suggest a predator-prey relationship between D. sayi and C. spp. Additional research to test prey
preference of mud crabs for Crepidula vs. Mytilus is being conducted to elucidate the underlying causes of these
observed patterns.
Catastrophic disturbance, ecosystem degradation, and population phase shifts in Chesapeake Bay
Romuald N. Lipcius* and Rochelle D. Seitz. Virginia Institute of Marine Science, The College of William and
Mary, Gloucester Point, VA 23062, USA.
Rapid, non-linear ecosystem alterations have been demonstrated in lakes, oceans, coral reefs, forests, and arid lands.
These drastic changes in ecosystem state are often facilitated by loss of ecosystem resilience due to environmental
degradation, and may be subsequently triggered by catastrophic perturbations. We present evidence for a dramatic
ecosystem alteration in an estuarine system, as evidenced by population phase shifts of floral and faunal species in
Chesapeake Bay due to a catastrophic disturbance, Hurricane Agnes, in 1972 subsequent to extensive environmental
degradation and loss of resilience. A similar and long-lasting ecosystem alteration occurred in the seaside lagoons
of Chesapeake Bay following a 1933 hurricane, the Storm King. These findings highlight the dynamic nature of
estuarine ecosystems, whose community structure is governed jointly by chronic (e.g., overfishing, pollution) and
acute (e.g., catastrophe) disturbances.
Chemical and molecular characterization of ontogenetic shifts in the chemical defense in Bugula neritina
(Bryozoa)
Nicole Lopanik,1* Niels Lindquist,2 and Nancy Targett.1 1University of Delaware College of Marine Studies, 700
Pilottown Rd, Lewes, DE 19958, USA; 2University of North Carolina Institute of Marine Sciences, 3431 Arendell
St., Morehead City, NC 28557, USA.
Bugula neritina is a bryozoan found in temperate marine habitats throughout the world. Previous research has
established that the physically vulnerable larvae of B. neritina are chemically distasteful to both vertebrate and
invertebrate predators. Adults, however, do not possess this chemical defense. Bioassay-guided fractionation of
larval extracts has resulted in the isolation of 3 active compounds. NMR and mass spectral data of the deterrent
compounds, as well as other related but non-deterrent compounds indicate that they are bryostatins, which are
polyketide macrolides. This is the first report of an ecological role for the bryostatins. Bryostatin levels fell sharply
following larval metamorphoses so that 2-3 d old juveniles had undetectable levels of these compounds, coupled
with a similar decline in deterrency. This precipitous decline in bryostatin levels following larval settlement and
metamorphosis was not due to the increase in structural material per unit volume of juveniles or adults. It has been
hypothesized that the bacterial symbiont, Canditatus Endobugula sertula, which resides in larval and adult tissue,
produces the bryostatins. There are several possibilities to account for the ontogenetic changes in the concentrations
of the unpalatable bryostatins. A molecular probe based on the ketosynthase module of the polyketide synthase was
developed to determine when the gene is being expressed throughout the different stages. Two clone products were
related to bacterial ketosynthases, and probes based on the sequences were made. One probe, when applied in RTPCR shows expression in larval tissue. When applied using quantitative RNA techniques, this probe should allow
us to distinguish how the differential production of these defensive compounds is regulated in B. neritina as it
transitions through these vulnerable juvenile stages, and may lend insight into how E.sertula is involved in the
biosynthesis of the bryostatins.
Mining biodiversity: molecular profiles of eubacterial associates of Caribbean marine sponges
Jose V. Lopez,* Cheryl L. Peterson, P. J. McCarthy, Holly Page, T. Pitts, and Shirley A. Pomponi. Division of
Biomedical Marine Research, Harbor Branch Oceanographic
Institution, 5600 US Hwy 1, Ft. Pierce, FL 34946, USA.
Our laboratory has been characterizing the microbial consortia of several different Caribbean marine demosponge
species using molecular genetics techniques as part of a survey of cryptic biological diversity in the sea. Our
primary interests have been to determine the extent of specific microorganismal associations (or "symbioses") with
sponges and consequently any metabolic mutualisms and exchanges that may stem from these associations,
especially in the context of secondary metabolite biosynthesis. The primary methods used for the identification of
eubacterial isolates was amplification of 16S-like rRNA and polyketide synthase (PKS) gene fragments using the
Polymerase Chain Reaction (PCR), DNA sequencing, REP-PCR fingerprinting and molecular phylogenetics
analyses. Congruence between the disparate gene and template datasets is explored for molecular evolutionary
implications, such as the potential of horizontal gene transfer or molecular adaptations (positive selection). 16S
rRNA profiles were also
compared between cultured isolates and uncultured environmental clones. Results to date confirm a wide
phylogenetic diversity of microbes that are positive for polyketide biosynthetic gene sequences within the sponge
hosts sampled. Most 16S rRNA gene sequences from uncultured DNA samples clustered separately from isolates.
Cultured alpha proteobacteria appeared ubiquitous among all hosts and closely related by their 16S rRNA genes. In
contrast, Gram+, gamma, beta and cytophaga eubacterial clades exhibited deep roots and long branch lengths,
suggesting novel isolates and/or clones, or perhaps relative genetic isolation stemming from specific symbioses or
co-evolution.
Assessing the roles of habitat complexity and scale in oyster reef restoration
Mark Luckenbach,* P. G. Ross, Alan Birch, Stephanie Bonniwell, and Susan Spears. Virginia Institute of Marine
Science, Eastern Shore Laboratory, College of William and Mary, Wachapreague, VA 23480, USA.
Current attempts to restore biogenic oyster reefs along the US Atlantic coast rely on the placement of material (shell,
limestone marl, concrete and other substrate) on the seabed to provide foundations for reef development.
Unfortunately, substrate is costly, oyster recruitment rates are reduced over historical levels and oyster mortalities
are often high. Thus, there is a premium on optimizing the habitat design to maximize the recruitment and survival
of oysters. We have conducted manipulative experiments over varying scales to test the effects of position in the
estuary (1 – 10 km), reef size (100’s of m), position on the reef (10’s of m), interstitial space (cm’s) and surface
rugosity (mm’s) on the settlement and early post-settlement survival of oysters. Reef foundations of varying sizes
were established in a large-scale, replicated block design in a tributary of the lower Chesapeake Bay and oyster
recruitment and early post-settlement survival patterns determined. In another experiment we manipulated substrate
particle size (and thus interstitial space) and particle surface complexity (rugosity) to elucidate the effects of habitat
complexity on the scale of individual oysters. Our results reveal significant variation in recruitment and early postsettlement survival from the largest basin-wide scale to small-scale effects of interstitial space and surface rugosity.
These findings provide insights into how habitat complexity can be manipulated to enhance restoration efforts.
The role of post-settlement mortality in recruitment of encrusting organisms associated with intertidal and
subtidal sabellariid reefs in Boynton Beach, Florida
Daniel A. McCarthy.* Smithsonian Marine Station at Fort Pierce, 701 Seaway Drive, Fort Pierce, FL 34949, USA.
Seasonal recruitment patterns of encrusting organisms into intertidal and subtidal sabellariid worm reef habitats off
Boynton Beach, Florida were followed from June 1997 to January 2000. Caged and uncaged settlement plates were
exchanged every month to determine the effects of predation on the number of species, and on the abundance of several
solitary species. During this study, twenty-three species of encrusting organisms were observed to recruit on settlement
plates. The sabellariid Phragmatopoma l. lapidosa was the encrusting species most commonly observed settling during
the study. The number of species recruiting was usually higher in subtidal than intertidal habitats. Many of the
encrusting species recruited to both habitats, although they generally were found at greater abundance in one habitat.
Recruitment occurred on all plate types, but was usually higher on the control and enclosed plates than on the exposed
plates. For most species differences in recruitment patterns between intertidal and subtidal habitats could not be
explained by predation on recruits. During peak recruitment, P. l. lapidosa may limit recruitment of other encrusting
species by covering over them. Additionally, high juvenile mortality in these other species is caused by frequent sand
scouring or burial.
The Keys Marine Laboratory: a research and education facility in the Florida Keys
Kevin McCarthy.* Florida Institute of Oceanography, Keys Marine Laboratory PO Box 968, Long Key FL 33001,
USA; e-mail kevin.mccarthy@fwc.state.fl.us.
The Keys Marine Laboratory is a state supported, university affiliated research and education facility. The lab is
located in the Florida Keys adjacent to the extensive seagrass and mangrove systems of Florida Bay and is near the
Florida reef tract. Researchers have used the KML in a variety of ways ranging from a base for sample collection to
a site for extensive mesocosm based manipulative experiments. During the five-year period, 1996-2000, there were
167 research projects conducted through KML and 33 additional projects for which more than 10,000 specimens
were collected by laboratory staff. Those projects have resulted in over 300 publications, abstracts, and reports.
The KML has also served as the location for valuable contributions to the education and training of undergraduate
and graduate students. In the past five years 101 separate educational institutions have utilized the KML totaling
225 student groups and more than 15,000 student days at the facility. The lab includes nine buildings on eight acres
situated between US Highway 1 and Florida Bay and is a two-hour drive from Miami. Approximately 25% of the
property consists of salt water holding facilities, a 2,082,400 liter series of five connected flow-through shallow
ponds and a variety of tanks ranging in size from 61 to 3,800 liters. The buildings include two dormitory units with
cooking facilities, accommodating up to 24 residents. Also on site are administrative offices, a small conference
room, a chemistry laboratory, a diving locker with compressor, laundry facilities, a small machine shop, a
classroom/conference room, computer laboratory, wet laboratories and dry laboratories. Two additional buildings
are used to house groups of from one to six visiting scientists requiring long-term accommodations. Other resources
of this full service marine laboratory include marina facilities and a fleet of eight vessels from 10 to 26 feet in
length.
Indiscriminate fusion of swimming sponge larvae
Katie E. McGhee.* Department of Biological Science, Florida State University, Tallahassee, Florida 32306-1100;
e-mail kmcghee@bio.fsu.edu.
For sedentary marine invertebrates, allorecognition systems allow individuals to distinguish between genetically
similar and distinct tissue they may encounter and are thought to reduce tissue fusion with individuals other than self
or kin. However, the costs and benefits associated with fusion at a sessile adult stage may be drastically different
than those associated with fusion at a mobile larval stage where size may be critical and encounters can be avoided
or pursued. The purple sponge, Haliclona sp., releases free swimming larvae that fuse and produce swimming
chimeric larvae without loss of metamorphic ability. Using these larvae, I investigated the effect of relatedness on
larval fusion frequencies and whether larvae can distinguish between siblings, larvae from sponges at the same site,
and larvae from sponges on islands separated by over a kilometer. Fusion frequencies averaged 13.4% and did not
differ significantly between larval treatments indicating that larvae are unable to distinguish between individuals of
varying relatedness. In addition, adult sponges differed significantly in the propensity of their larvae to fuse,
suggesting the presence of individual strategies influencing the behavior of their larvae. These results indicate that
contrary to the predictions of self- or kin-recognition theory, factors other than relatedness may be involved in
determining the likelihood of larval fusion.
Responses of juvenile and adult Streblospio benedicti (Spionidae) to chemical cues bound to glass microbeads
H. K. Mahon* and D. M. Dauer. Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA; email hmahon@odu.edu; ddauer@odu.edu.
Spionid polychaetes feed at the sediment-water interface using a pair of ciliated palps. Spionids select food particles
based upon characteristics including size, texture and specific gravity. In addition, chemical cues also play an important
role in selectivity. Juvenile and adult spionids may have different stable isotopic carbon signals, indicating the potential
to differentiate chemical cues ontogenetically. In the present study, we tested the responses of juvenile and adult
Streblospio benedicti to seven chemical cues bound to glass microbeads (five amino acids and two carbohydrates). All
chemicals used were previously shown to increase feeding rates of spionids. For all seven chemical cues, juveniles and
adults were highly selective of organically coated beads over uncoated beads (greater than 70%). Two of the cues
showed significant differences between juveniles and adults. Juveniles were highly selective for threonine while adults
were highly selective for proline.
Functional morphology of the setae of the slipper lobsters Scyllarides latus, S. aequinoctialis and S. nodifer's
pereiopods
Cassandra Malcom* and Kari Lavalli. Southwest Texas State University, San Marcos, TX, USA
Setae of the pereiopods of three species of slipper lobsters, Scyllarides latus, S. aequinoctialis and S. nodifer (family
Scyllaridea), were examined with a scanning electron microscope (SEM) and environmental electron microscope
(EEM). The position, distribution, and structure of the setae was compared to the setae of members of two more
commonly studied families of lobster: nephropids (American clawed lobster, Homarus americanus) and palinurids
(Caribbean spiny lobster, Panulirus argus). These two families have been found to have very setose pereiopods with
different setal types that function as both contact chemoreceptors (taste) and distance chemoreceptors (smell); some,
such as hedgehog hairs and serrate setae, can function as both chemo- and mechanoreceptors. However, rather than
having many types of setae like the nephropids or palinurids, we have only found simple and cuspidate setae on S.
latus, S. aequinoctialis and S. nodifer. Slipper lobsters have hairs only at the proximal end of the dactyl and spread
throughout the remaining segments (propus, carpus, merus, ischium, basis) of each non-chelate pereiopod. Tufts of
these setae are found on the dactyl, while the remaining segments have setae spread randomly on their surface.
Videotapes of feeding by these lobsters on bivalves indicates that they use the hard, nail-like dactyls to pry open the
bivalves, whereupon they use their larger first pereiopods to hold the bivalve shell open and their second pereiopods
to cut the bivalve's adductor muscles. Because of this feeding mode, hairs on the tips of the dactyl would be broken
and damaged, presumably affecting their function. Thus, the location of hairs at only the proximal ends of the
dactyl allows the lobster to use the dactyl tips as cutting appendages. We expect that neurological examination of
the hairs at the proximal end of the dactyl will show those hairs to be chemosensory in function.
Interannual growth rate variation in the soft-shelled clam, Mya arenaria, and its relation to interannual
temperature differences and habitat at Maquoit Bay, Maine
Kate R. Meltzer* and William G. Ambrose, Jr. Biology Department, Bates College, Lewiston, ME 04240, USA.
Internal annual growth bands in the soft-shelled clam, Mya arenaria, were used to determine age and growth rates of
individuals collected different areas of Maquoit Bay, Maine. An annual index of growth was developed for years
1991 to 2001, accounting for age differences in growth rates using the von Bertalanffy equation. Interannual
variations in growth were then related to interannual differences in temperature (air and water) and habitat (seagrass
versus mudflat). Average lengths of two- and three-year old clams from Maquoit Bay were 38%-60% greater than
two-and three-year old clams from six sites in a 1980 Maine study. Mya typically exhibits slow growth during
winter, however the large size of young clams in recent years may be the result of milder winters that permitted
faster growth. Therefore, we expect to find a strong positive correlation between warmer winter temperatures and
faster clam growth. Seagrass in Maquoit Bay (45%, SD = 8% cover, shoot biomass = 7.8g, 2.9g; root biomass =
3.8g, 2.3g; and canopy heigh t= 31.4cm, 4.9cm) decreases water flow by 50% which may reduce food delivery.
Nevertheless, preliminary results indicate that there is no difference in growth rate inside and outside the grassbed.
The variable effects of suspension feeders and nutrient enrichment on phytoplankton biomass in intertidal
pools on Swan’s Island, Maine
Elizabeth T. Methratta.* University of Pennsylvania, Department of Biology, Philadelphia, PA 19104-6018, USA.
Questions of top-down/bottom-up regulation have been difficult to test experimentally in marine settings because
nutrient manipulations are impractical in open systems. With few experimental studies addressing the roles of
nutrients in marine systems, our understanding of how nutrients influence marine communities remains limited.
Nutrient enrichment is suspected to play a prominent role in structuring intertidal pool communities. Tidepools on
Swan’s Island, Maine that receive natural nutrient enrichment contain more phytoplankton biomass and fewer
benthic organisms compared to those tidepools that are not nutrient enriched. The role of suspension feeders is
unclear, because they may either reduce phytoplankton biomass by consumption, or increase phytoplankton biomass
by enhancing the cycling of limited nutrients. Moreover, some suspension feeders are inefficient at retaining
particles smaller than 2 to 5 micrometers in diameter, and so they may also cause shifts in the size distribution in the
phytoplankton assemblage. Here I present the results of a 2-by-2 factorially designed experiment in which the
factors of nutrients (ambient versus enriched) and planktivory by the blue mussel, Mytilus edulis, (mussels present
versus mussels absent) were manipulated, and the response of phytoplankton biomass was measured over the course
of several weeks. Initially, tidepools that received both nutrients and mussels showed greater phytoplankton
biomass compared to others, although this effect was reversed on subsequent sampling dates, with these
nutrient+mussel tidepools showing lower phytoplankton biomass compared to other treatments. Nutrients added
alone had little positive effect on phytoplankton biomass. These results indicate that in intertidal pool communities,
benthic suspension feeders are linked tightly to phytoplankton production by consumption and by nutrient cycling,
and that these effects vary over time.
Patterns of herbivory and seaweed abundance in Florida Keys no-take reserves
Margaret W. Miller.* NOAA-Fisheries, Southeast Science Center, 75 Virginia Beach Dr., Miami FL 33149, USA.
Assessment of total seaweed biomass and herbivory pressure (using rope assays) has been undertaken at least
semiannually in three no-take reserves and three adjacent reference sites in the Florida Keys National Marine
Sanctuary (FKNMS) since reserve inception in 1997. The study was designed to test the hypothesis that top
predator replenishment in FKNMS reserves would depress herbivore populations and, hence, herbivory, yielding
higher seaweed abundance in no-take reserves. Seaweed abundance was highly variable and no treatment (Reserve
vs. Reference) patterns are evident. Seaweed community analysis (using PRIMER v5 software) suggests deep
(~18m) and shallow (~9m) communities are distinct so they were subsequently analyzed separately. Initially,
shallow sites were quite homogenous and hence represent good “replicates” while the deep sites showed more
differentiation at the initial (Oct.97) sampling. Slight differentiation of shallow Reserve vs. Reference seaweed
assemblages was evident in recent samples while no such differentiation was indicated in recent deep
samples.Relative herbivory between some reserve/reference site pairs appears to have shifted over the course of the
project, but this is due most clearly to increase in herbivory at a single reference site and, perhaps, smaller decrease
its reserve site pair.
Reef discovery, utilization and conservation in Antongil Bay, Republic of Madagascar
Kenyon Mobley,1* Phaedra Doukakis,2,3 and Mananjo Jonahson.3 1Georgia Institute of Technology, School of
Biology, 310 Ferst Dr. Atlanta, GA 30332-0230; e-mail gtg842d@prism.gatech.edu; 2Wildlife Conservation Society,
2300 Southern Boulevard, Bronx, New York, 10460, USA; e-mail pdoukakis@wcs.org; 3Wildlife Conservation
Society, Villa Ifanomezantsoa, Face II A 78 D, Soavimbahoaka; e-mail wcsmad@bow.dts.mg.
Antongil Bay is a large estuary situated on the northeastern coast of Madagascar that supports a diversity of marine
life including mangrove, seagrass, and coral reef communities. Despite the recent designation of two marine
protected areas within the Bay as part of the Masoala National Park, the Bay remains relatively unexplored. During
a recent field expedition, previously unknown reefs within the Bay (five eastern and one western) were surveyed for
invertebrate taxa and relative coral cover. Eastern portions of the Bay support mixed coral/algal communities with
comparatively higher species diversity than the western reef and are influenced by high turbidity and freshwater
influx. The western reef, on the other hand, has a higher relative coral cover, lower invertebrate species diversity
and is dominated by branching corals, principally Acropora spp. Future expeditions in the Bay are likely to reveal
previously undocumented reef locations.
Interviews with local fishermen were conducted to identify target species, historical fishing grounds and the extent
to which the reefs are presently exploited. Spearfishing, gill netting, and traditional hook and line methods are
typically employed to catch reef fishes. We found reef fishing practices to be largely nondiscriminatory, and most
all species of fishes are harvested and consumed. Reef invertebrates including sea cucumbers, tradacnid clams, and
anemones are also harvested for subsistence-level consumption. As terrestrial resources throughout Madagascar
disappear at an unprecedented rate, we predict marine resources may suffer from increased utilization and habitat
degradation. Therefore continued research would benefit the development of appropriate management programs for
reefs within Antongil Bay.
How does wave action stimulate thread production in Mytilus edulis?
G. M. Moeser* and E. Carrington. Department of Biological Sciences, University of Rhode Island, 100 Flagg Rd.,
Kingston, RI 02881, USA.
Sessile organisms on wave-swept shores must develop a means to remain attached to the substrate under a variety of
conditions in order to survive. The mussel, Mytilus edulis, is a competitively dominant organism in this dynamic
environment in part due to its ability to maintain a strong byssal attachment. Previous studies have suggested that
M. edulis responds to increased wave action by increasing attachment strength through the production of more
byssal threads, and it has often been assumed that flow is the main stimulus for this response. However, it remains
unclear what specific aspects of wave action cue increased thread production. Mussels may potentially respond not
only to unidirectional flow, but also to acceleration (flow-induced vibrations of the shell) or byssal loading (tension
transferred from the threads to the byssal retractor muscles). This study focuses on the influence of acceleration and
loading on the dynamics of M. edulis attachment strength. Field collected mussels were exposed to one of four twofactor treatments, consisting of (1) the presence or absence of mussel acceleration and (2) the presence or absence of
fluctuating load on the mussel byssus, and the subsequent number of byssal threads produced was monitored. The
relative importance of acceleration and loading in stimulating thread production will be discussed.
Biodiversity of Bear Seamount, New England seamount chain: results of exploratory trawling
J. A. Moore,1* M. Vecchione,2 K. E. Hartel,3 B. B. Collette,2 J. K. Galbraith,4 R. Gibbons,2 M. Turnipseed,5 M.
Southworth,5 and E. Watkins.5 1Florida Atlantic University, Honors College, Jupiter, FL 33458, USA; e-mail
jmoore@fau.edu; 2National Marine Fisheries Service, National Systematics Laboratory, National Museum of Natural
History, Smithsonian Institution, Washington, DC 20560, USA; 3Museum of Comparative Zoology, Harvard
University, Cambridge, MA 02138, USA; 4National Marine Fisheries Service, Northeast Fisheries Science Center,
Woods Hole, MA 02453, USA; 5Virginia Institute of Marine Sciences, Gloucester Point, VA 23062, USA.
Bear Seamount (39°55’N 67°30’W) is an extinct undersea volcano located inside the U.S. Exclusive Economic
Zone south of Georges Bank. The fauna associated with the seamount was little known until twenty trawl stations
were made December 2-7, 2000, by the NOAA research vessel Delaware II. The objective of the cruise was to begin
documenting the biodiversity on and over the seamount, particularly of fishes, cephalopods, and crustaceans.
Representatives of most species were preserved as vouchers for subsequent definitive identification. Preliminary
identifications indicate the capture of 115 fish species. Among these were a number of new fish records for the area
or rare species, including Acromycter pertubator (Congridae), Alepocephalus bairdii (Alepocephalidae),
Mirognathus normani (Alepocephalidae), Bathygadus favosus (Bathygadidae), Nezumia longebarbata
(Macrouridae), Gaidropsarus argentatus (Phycidae), and Dibranchus tremendus (Ogcocephalidae). Cephalopods
comprised 26 species in 15 families, including one new distributional record and several rarely-collected species.
The crustacean fauna was diverse with at least 46 species. Totals for other invertebrate species are pending
laboratory identification, but number at least 113 species in 10 phyla. This includes a number of new distributional
records and a new species of gorgonian.
Do regional assembly rules determine the structure of coral reef assemblages in the Indo-Pacific Ocean?
Camilo Mora,* Paul Chittaro, and Peter Sale. Biology Department, University of Windsor, 401 SUNSET WindsorOntario, N9B 3P4-Canada; e-mail moracamilo@hotmail.co.
Throughout the history of ecology many interesting patterns have been found, but explaining them has often been a
major challenge. A recently reported pattern among coral reefs of the Indo-Pacific is that the proportion of species
among families is highly predictable, for both fishes and corals, based on the local pool of species. It has been suggested
that such a pattern arises through the action of regional assembly rules in which life-history characteristics of the families
influence the species composition in any coral reef assemblage. We tested the existence of assembly rules by comparing,
for local species pools, the proportional distribution of species among families with output from a null model in which
species were allocated randomly to Pseudo-families. We found that species richness in any family can predict very
accurately the size of the local pool of species in any Indo-Pacific locality. However, equally speciose Pseudo-families
yielded similar levels of predictability. Obviously, coral reef assemblages are extraordinarily ordered but since Pseudofamilies also predict the local pool of species such order is unlikely due to any assembly rule imposed by families’ traits.
How this pattern may arise randomly is discussed.
Hard clam (Mercenaria mercenaria) restocking efforts via larval injection: preliminary results on settlement
success
D. Morales,1* E. Irlandi,1 W. Arnold,2 and S. Herber.1 1Department of Marine and Environmental Systems, Florida
Institute of Technology, Melbourne, Florida, USA; 2Florida Marine Research Institute, St. Petersburg, Florida,
USA.
The hard clam, Mercenaria mercenaria, is an important fisheries resource along the east coasts of the USA. In the
Indian River Lagoon along the east central coast of Florida, clam populations have been significantly reduced by
overfishing and altered salinity regimes due to water-management strategies. A variety of restocking efforts are
being investigated by the State to re-establish hard clams in the lagoon. We have been evaluating the potential of
direct larval injection as a means of restocking. Initial studies indicate that mortality at settlement and early
recruitment stages may be limiting successful establishment of hatchery-reared eggs and larvae that have been
released directly into the lagoon. To further examine the role of predation, we enclosed a ca. 10-m-diameter area of
water column and seafloor with a sediment-retention screen that extended from the sediment to the water surface.
Three plot types (1-m2 plots) were established within each enclosure: oyster shell hash, vexar mesh screens, and
natural bottom. The shell hash and vexar were used to examine if different methods of predator exclusion
influenced settlement and recruitment. Hatchery-reared competent larvae were released into the enclosure. After 24
hours the sediment curtain was removed to allow predators access to the plots and the newly settled clams.
Sediment cores were taken after removal of the curtain and monthly thereafter to monitor larval settlement and
survival. After 4 months we have not recovered any M. mercenaria in the samples. Potential explanations for lack
of successful settlement include: predation, sediment type, water temperature at time of release, and insufficient time
to allow settlement before removal of the retention screen resulting in transport of larvae out of the sampled area.
Additional experiments are planned to continue the evaluation of this method as a means to create localized patches
of clams to contribute to a spawning population.
Green turtle grazing: effects on structure and productivity in seagrass beds
Kathleen Moran* and Karen Bjorndal. Archie Carr Center for Sea Turtle Research, Department of Zoology,
University of Florida, P.O. Box 118525, Gainesville, FL 32611, USA.
Seagrass beds are important and productive habitats in Caribbean marine ecosystems. Seagrass blades serve as
surfaces for epibionts and traps for detritus, while seagrass pastures are nurseries for many juvenile organisms.
Thalassia testudinum is the most robust Caribbean seagrass, often forming extensive, monospecific pastures. Green
turtles (Chelonia mydas) are the primary herbivores in many Caribbean Thalassia beds. They can maintain grazing
plots for a year or longer, in which they re-crop seagrass blades near the substrate. Today, green turtles are
endangered throughout the Caribbean and represent perhaps 1% of historical populations, which numbered in the
tens of millions. Productivity and structure of seagrass habitats are undoubtedly different today than when they
were grazed by millions of green turtles. Green turtle grazing was simulated in Thalassia plots from July 1999November 2000 at Lee Stocking Island, Exumas, Bahamas. Seagrass blade structure, productivity, and nutrient
composition were quantified initially and at intervals during the grazing experiment. Some of these parameters
changed, as re-cropping stressed the plants. As efforts are made to increase green turtle populations, realistic goals
of population size are needed for management programs. Incorporating grazing-induced changes in Thalassia
productivity and nutrient composition can improve current estimates of seagrass carrying capacity for green turtles.
Infaunal colonization and succession in a 21-acre disturbance: the creation of the Friendship marsh
S. Moseman,* C. Forder, and L. Levin. Biology Department, University of California, San Diego, Ca 92122, USA.
The destruction of wetland habitats, particularly in southern California, has spawned efforts to artificially create salt
marshes. While artificial marshes are often intended to compensate for lost habitat, they may also be viewed as
large-scale disturbances for the purpose of ecological studies. The 21-acre Friendship marsh in Tijuana Estuary
provides a unique opportunity to examine infaunal response to disturbance at a scale that far surpasses those often
studied in manipulative experiments. This study characterizes the early colonists of mudflat and S. foliosa habitat
within the Friendship marsh. In the early months of marsh establishment, dipteran larvae and the naidid oligochaete,
P. litoralis, dominated the infaunal community. These taxa were shown to arrive into the marsh via algal rafts and
passive transport. Comparison of samples from algal rafts and larval/bedload collectors revealed that both modes of
introduction were utilized by infaunal taxa during the first 6 months of marsh establishment. This study also
characterized the successional trajectory of the macrofaunal assemblage, which transitioned from insect domination
to increased representation of spionid polychaetes, during the marsh’s first 2 years. There was no influence of
vegetation on infaunal trajectories. Rather, similar sediment organic matter and salinity between the created marsh
and an adjacent natural S. foliosa habitat more directly influenced the early infaunal community. By 14 months of
age, the Friendship marsh achieved comparable species richness and density to that of the natural habitat, although
infaunal density declined at 21 months. These results suggest that environmental parameters and life-history traits
may particularly govern successional trajectories and limit recovery rates when the scale of disturbance is large.
Shifts in wetland community composition across estuarine salinity gradients: physical and biological
determinants
Caitlin Mullan,* Mark Bertness, and Brian Silliman. Department of Ecology and Evolutionary Biology, Box G-W,
Brown University, Providence, RI 02912, USA; e-mail Caitlin_Mullan@Brown.edu.
Elucidating the mechanisms that generate species distribution patterns is critical to preserving landscape community
structure and to predicting the effects of anthropogenic change to the environment. In estuaries, plant community
composition changes dramatically from salt marshes near the coast to tidal freshwater marshes upriver. Current
models of coastal marshes assume that salinity stress alone dictates the zonation of species along this environmental
stress gradient, but this hypothesis has never been tested. We conducted reciprocal transplant experiments between
salt and fresh-tidal marsh dominant plants with and without neighboring native vegetation to investigate the roles of
physical stress and biotic interactions in controlling species distribution in a Rhode Island estuary. After one
growing season, the salt marsh grasses Spartina patens and Spartina alterniflora transplanted into a fresh-tidal
marsh with neighboring vegetation removed were performing as well as, or better than, in their native habitat, but
were etiolated and dying when neighbors were included. Fresh-tidal marsh dominants, Typha angustifolia and
Scirpus americanus, died within weeks of transplanting into a salt marsh regardless of neighbor treatment. These
results indicate that competition for resources, in addition to physical factors, regulates the distribution of wetland
plants across salinity gradients. In addition, results from this study suggest that the theory developed along vertical
gradients in the intertidal, that superior competitors dominate physically benign habitats and displace weaker
competitors to physically harsh habitats, may be generalizable to horizontal environmental gradients.
Pen shell community patterns and assemblage: local and regional dynamics
Pablo Munguía.* Department of Biological Science, Florida State University, Tallahassee, FL 32306-1100, USA.
The interaction between local and regional diversity patterns has been a major focal point in ecology. Theory
predicts one of two outcomes: (1) diversity at the local scale is a constant proportion of diversity at a regional scale.
(2) Local diversity saturates at higher regional richness. The second outcome has been difficult to observe in nature
due to three main reasons: problems in delimiting a species pool, pseudoreplication, and assuming that communities
are at some equilibrium. Here I incorporate the relative abundance of species and assembly time to show how the
relationship between local and regional diversity develops during different colonization times. At St. Joe Bay,
Florida, the pen shell (Atrina sp.) is one of the few sources of hard substrate, serving as a habitat for sessile and
mobile invertebrates and fish. During the summer of 2001 I placed empty pen shells spread among different plots
within the bay and removed them at different time intervals. The results showed that with time, species richness
increases significantly while evenness indices saturate. Initially a local-regional plot of species richness shows that
few species are present at the local scale, regardless of the species pool size. With time the slope between local and
regional richness increases, presenting unsaturated communities. Rarefying the number of species at the local scale
and comparing them to the regional species pool shows a different pattern. With rarefied richness there is a positive
linear relationship between local and regional richness initially, but at subsequent times the curve saturates. These
results suggest two things: (1) the degree of species saturation will depend on the colonization stage of a
community. (2) Incorporating species abundances (i.e. through rarefaction or other techniques) demonstrates the role
of species commonness or rarity in determining patterns of community diversity at different scales.
Predation on seeds of seagrasses by a tanaid crustacean Zeuxo sp.: impact on seed production of Zostera
marina and Zostera caulescens
Masahiro Nakaoka.* Graduate School of Science and Technology, Chiba University, Inage, Chiba 263-8522,
Japan; e-mail nakaoka@life.s.chiba-u.ac.jp.
I report the first evidence of seed predation by a tanaid crustacean on seagrasses Zostera marina and Zostera
caulescens in Otsuchi Bay, northeastern Japan. A tanaid Zeuxo sp. was found to live in spathes of the seagrasses.
Spathes with the tanaid were observed to have bored seeds. Laboratory observation revealed that the tanaid
consumes seeds by drilling a hole. For both seagrass species, tanaids and bored ovules were not observed for
spathes before anthesis, whereas spathes with bored seeds and density of the tanaid increased from June to August
after anthesis. In August, 14% and 27% of seeds were found bored in Z. marina and Z. caulescens, respectively,
suggesting that seed predation by the tanaid has considerable negative impact on seed production of the seagrasses.
The seed predation was also observed in another seagrass bed at Funakoshi Bay, adjacent to Otsuchi Bay, where the
tanaid consumed ca 30 % of seeds of Z. caulescens. Some adult individuals of Zeuxo sp. in spathes had brood
pouches containing eggs and juveniles. A large number of juveniles were found in spathes in August. Thus, the
tanaid utilizes seagrass spathes not only as feeding site, but also as place of reproduction and a nursery.
A probabilistic assessment of benthic condition of California estuaries: results from the National Coastal
Assessment 1999
Walter G. Nelson,* Henry Lee II, and Janet Lamberson. National Health and Environmental Effects Research
Laboratory, Pacific Coastal Ecology Branch, Western Ecology Division, US EPA, Newport, OR 97365, USA.
As part of the National Coastal Assessment, the Environmental Monitoring and Assessment Program of EPA is
conducting a three year evaluation of benthic habitat condition of California estuaries. In 1999, probabilistic
sampling for a variety of biotic and abiotic condition indicators was conducted at eighty stations in all California
estuaries except San Francisco Bay, which was sampled in 2000. Assessment results indicate that only a small
percentage of the total area of these estuarine systems has levels of sediment contamination of either metals or
organic compounds potentially toxic to benthic organisms. These results were confirmed by a general absence of
elevated mortality in sediment bioassays conducted with two amphipod species. Nonindigenous species were
present at many sites and were the numerical dominants at several, but overall constituted only ~2% of the total
fauna compared to 11% in highly invaded San Francisco Bay (previous studies). Within California’s small estuaries,
nonindigenous species may be a more widespread form of disturbance to benthic communities than sediment
chemical contaminants.
Recovery of a U.S. Virgin Islands red hind spawning aggregation following protection
Richard S. Nemeth, Adam Quandt, and Laurie Requa.* Center for Marine and Environmental Studies, University of
the Virgin Islands, #2 John Brewers Bay, St. Thomas, USVI 00802, USA.
The Red Hind Marine Conservation District is an important grouper spawning aggregation site that was heavily
fished for many years during the annual spawning season (December through February). The Red Hind Bank was
closed seasonally in 1990 in response to the declining size and number of spawning red hind (Epinephelus guttatus).
In 1999, this area was designated a Marine Conservation District (MCD), which prohibits all fishing year-round. To
document the recovery of the red hind spawning aggregation, 1800 fish were captured, measured, tagged with
numerically coded anchor tags, and released over a two year period. Length measurements and visual counts of
spawning fish were compared to historical data. Our data indicate that the size of red hind increased from 29.5 cm
(11.6 in.) in 1988 to 38.8 cm (15.4 in.) in 2000. The average number of spawning red hind increased from 5 to 25
fish/ 100m2, between 1997 and 2001. The increase in the size and number of red hind indicates that the MCD has
provided adequate protection to reverse the negative population trend for this species. During the study 21 tags were
returned for a reward and catch information was documented. Results show that the majority of tagged fish migrated
10 to 30 km to the west of the spawning ground to an area between St. Thomas, USVI and Culebra and Viequez,
Puerto Rico. Continued protection of the red hind spawning aggregations will mean greater reproductive output for
this population and better catches in the near future for commercial fishermen of the Virgin Islands. This protection
will also mean an increase in other species within the MCD. It is predicted that if we set aside 20% of our marine
resources as marine protected areas we will gain the greatest benefit to maintaining sustainable fisheries.
Settlement and survival of the oyster Crassostrea virginica on constructed oyster reef habitats in Chesapeake Bay:
how does reef architecture and construction material influence habitat restoration success?
Janet Nestlerode,1* Mark Luckenbach,2 and Robert Diaz.1 1Virginia Institute of Marine Science, Gloucester Point,
Virginia 23062, USA; 2Virginia Institute of Marine Science, Eastern Shore Lab, Wachapreague, Virginia 23480,
USA.
The objectives of oyster reef habitat restoration in Chesapeake Bay are not only the enhancement of oyster stocks, but
also to restore the physical structure and ecological services provided by these systems. Restoration efforts have focused
on reconstructing 3-dimensional reef habitats, yet a shortage of sufficient volumes of oyster shell for creating large-scale
reefs has lead to an evaluation of alternative base materials. Recent evidence has revealed the importance of two
components of reef architecture--vertical relief and interstitial space--on the development of oyster populations on
restored reefs and we will present data which show that oyster populations vary between reefs built using different
construction configurations and base materials. Oyster recruitment, survival, and growth are compared among intertidal
and subtidal reef mounds built with oyster (Crassostrea virginica) shell or surf clam (Spisula solidissima) shell. Results
indicate that intertidal oyster shell mounds support greater oyster growth and survival, offer the highest degree of
structural complexity, and maintain a more diverse and abundant macrobenthic community. The patterns observed give
context to the importance of substrate selection in similar restoration activities.
Oyster reef health in selected southeastern North Carolina tidal creek estuaries
Bethany Noller,* Jacqueline Horner, Martin Posey, and Troy Alphin. Department of Biological Sciences, University
of North Carolina at Wilmington, Wilmington, NC 28403, USA.
Due to impacts from various sources, such as increased development, declining water quality (caused by high
sedimentation and eutrophication,) and over-harvesting, the health of the oyster population in many areas along the
Atlantic and Gulf coasts is in question. Oysters have been identified as critical habitat for juveniles of many
important fisheries as well as having significant effects on water quality. They provide a key refuge and foraging
habitat for many estuarine residents, transient fish and decapods. However, the habitat function of the oyster reefs
may vary with reef structure, especially vertical relief, density, and edge characteristics. This study focuses on the
structural characteristics of oyster reefs found in the tidal creeks of New Hanover County, NC. The study was
conducted at Howe, Whiskey, Pages, and Hewletts creeks. Within each of these four creeks three oyster reefs were
selected. The percent coverage of shell hash and live or dead oysters was measured using ten replicate 30-cm by 30cm quadrats. Vertical relief was measured on each reef using ten meter square quadrats. We found strong variation
in reef morphology and extent among creeks emphasizing the need to examine habitat quality in addition to reef area
when comparing even closely spaced estuarine systems.
Effects of the invasion of the Asian shore crab Hemigrapsus sanguineus on resident crab populations
N. J. O'Connor.* Department of Biology and School for Marine Science and Technology, University of
Massachusetts Dartmouth, No. Dartmouth, MA 02747-2300, USA.
The Asian shore crab Hemigrapsus sanguineus is becoming established along the rocky intertidal coastline of New
England, reaching densities greater than in its native habitat. H. sanguineus occurs throughout the rocky intertidal
zone, overlapping in distribution with resident crab species such as green crabs (Carcinus maenas, another nonindigenous species) and mud crabs in the family Xanthidae. The objective of the study was to determine whether
populations of green and mud crabs are affected as H. sanguineus populations become established and increase in
size. Crab populations in several localities in Narragansett Bay, Vineyard Sound, and Cape Cod Bay were sampled
for 3-6 years, usually in the spring (May-June) and fall (September-October), to examine temporal changes in crab
populations and to determine whether any changes observed were similar at different locations. Three to five
replicate 2m2 square quadrats were randomly placed on rocky areas low in the intertidal zone during low tide. All
crabs in quadrats were identified, counted, measured in most cases, and then returned to the sampling site. Results
to date suggest that the establishment of H. sanguineus has negatively affected the abundance of xanthid crabs,
although the mechanism is unknown. H. sanguineus may also be impacting C. maenas, because densities were low
where H. sanguineus was abundant. Future sampling where C. maenas currently dominates is necessary to
determine whether C. maenas densities decline as H. sanguineus populations grow in size.
Vanadium in sea squirts: is heavy metal in bad taste?
Shobu Odate* and J. R. Pawlik. Center for Marine Science Research, University of North Carolina at Wilmington,
NC 28409, USA.
Ascidians may defend themselves from fish predators by producing secondary metabolites or sequestering acid, but
many species also accumulate heavy metals, most notably vanadium. The possible defensive function of heavy
metals in ascidians is unclear. Past studies have demonstrated that vanadium salts deter fish feeding, but our
preliminary results suggest that the same salts are not deterrent in fish feeding assays with the bluehead wrasse,
Thalassoma bifasciatum. However, vanadium occurs as haemovanadin in biological systems. We will assess the
effects of naturally occurring vanadium complexes and valences in assays testing anti-predator, anti-fouling and
anti-microbial effects.
“Where’s my sea whip?” Are defenses in Caribbean gorgonians physical or chemical?
William O’Neal* and Joseph R. Pawlik. Biological Sciences and Center for Marine Science, University of North
Carolina at Wilmington, Wilmington, NC 28409, USA.
Previous investigations have shown that gorgonians are defended from generalist fish predators by secondary
metabolites and calcitic spicules, but feeding assays in most of those studies were performed on the basis of tissue
mass, not volume. We re-evaluated chemical and physical defenses and examined the nutritional quality of 32
species of Caribbean gorgonians on the basis of tissue volume. Crude organic extracts from 100% of the gorgonian
species were deterrent toward the bluehead wrasse, Thalassoma bifasciatum, in laboratory feeding assays. Natural
volumetric concentrations of spicules from only two species (6.3%) were deterrent. There was no relationship
between gorgonian nutritional quality and the presence of chemical or spicule defenses. These results demonstrate
that chemical defense is the primary means by which gorgonians protect themselves from generalist fish predators
and that assay techniques may greatly influence the results of feeding experiments.
Distribution and abundance of zooplankton at three depth increments over a Florida coral reef
K. L. O’Neil,* K. B. Heidelberg, and K. P. Sebens. Department of Biology, University of Maryland, College Park,
College Park, MD 20742, USA.
Benthic suspension feeders and planktivorous fishes rely on zooplankton as a primary source of food. The
zooplankton found above coral reefs is made up of holoplankton, meroplankton, demersal and epibenthic plankton.
Zooplankton may be residents of the reef or pelagic plankton supplied to the reef by oceanic processes such as
internal waves. The majority of research on reef related zooplankton has focused on demersal forms, although
pelagic holoplankton can make up a significant portion of the zooplankton. In this study, a specially designed
plankton pump system was used to test for differences between the zooplankton population near the substratum, two
meters above the reef, and at the surface. Samples were collected six times daily for one week at all depths
simultaneously. Copepods were the most abundant group, primarily Oithona spp., nauplii, and Acartia spp.. No
difference in total zooplankton density was found with time of day, with high densities frequently occurring during
daytime hours at all depths. Temora spp, Calocalanus spp, and Corycaues spp. copepods were all found to be
significantly higher at the surface than at the substrate. Acartia spp. density was greatest at two meters and Oithona
spp. had equal density at all depths. All rare zooplankton taxa showed significant differences in density between
depths. The study discusses the importance of delivery processes and oceanic migration patterns on vertical
distribution of zooplankton in coastal areas. Our data shows that certain zooplankton taxa are more or less available
to benthic suspension feeders due to varying patterns of vertical distribution.
Estuarine infaunal responses to food enhancement: do patterns indicate specialist or generalist strategies?
M. Owens,* M. Posey, and T. Alphin. University of North Carolina at Wilmington, Center for Marine Science,
5600 Marvin K. Moss Lane, Wilmington, NC 28409, USA.
Studies of the effects of eutrophication on estuarine systems have focused on nutrient inputs and factors structuring
estuarine communities. We previously conducted a study examining the effects of bottom-up (resource) and topdown (predation) controls in benthic communities in four tidal creeks in southeastern North Carolina. Short-term
experiments and comparative studies were used to examine microalgal biomass, infaunal composition and
abundance, predator effects and nutrient variations among four estuaries that varied in background nutrient loadings.
The results from these studies were mixed and weak, showing few individual effects of nutrient enhancement and no
interactions between predation and nutrient inputs, in contrast to the predictions of a simple cascade model. Possible
explanations point to the opportunistic life histories of resident fauna and a lack of strong linkages between specific
food resources and infaunal growth and reproduction. We are initiating a series of experiments to determine the
relative growth, reproduction and survivorship of three infaunal species common in southeastern North Carolina in
response to varying levels of microalgal and detrital food resources, with objectives of determining resource
quality/quantity effects as well as understanding whether these species are specialist or opportunistic consumers.
Reliable information on the feeding habits of common infauna, including the degree to which they are opportunistic,
is essential to predicting and interpreting effects of bottom-up control in benthic communities.
Predatory-induced variability in the composition of decapod crustacean assemblages in the subtidal of central
Chile
Alvaro T. Palma,1* Mauricio Arriagada,2 Cael Orrego,2 and Anna Astorga.2 1Departamento de Ecología Costera,
Facultad de Ciencias, Universidad Católica de la Ssma. Concepción, Paicaví 3000, Casilla 297, Concepción, Chile;
2
Departamento de Ecología, P. Universidad Católica de Chile, Alameda 340, Casilla 114-D, Santiago, Chile.
Although common, and in some cases of commercial value, little is known about the mechanisms and processes that
affect the distribution and abundance of several decapod crustaceans along the coast of Chile. All these species have
planktonic larvae that must undergo settlement and recruitment before becoming part of the adult segments of their
populations. For several of these species, we detected the existence of newly settled individuals that display a
diverse degree of color polymorphisms. This pattern appears to be more pronounced in those species that are
detritivorous and is less evident in the carnivorous ones. Through the implementation of a meso-scale predatorexclusion experiment we were able to quantify the degree of relative protection that such cryptic coloration confers.
Our results suggest that the more cryptic species are more susceptible to be preyed upon by “blind” predators such
as other crabs, compared to the higher susceptibility of the less cryptic species to visual predators, such as demersal
fish.