Abstracts
(alphabetical by author)
A comparison of acoustic techniques, videography, and quadrat sampling for mapping and characterizing
subtidal oyster reefs
Jamie Adams,1* Raymond Grizzle,1 Larry Ward,1 Semme Dijkstra,2 and John Nelson.3 1Jackson Estuarine
Laboratory, University of New Hampshire, Durham, NH 03824, USA; 2Center for Coastal & Ocean Mapping,
University of New Hampshire, Durham, NH 03824, USA; 3New Hampshire Fish & Game Department, Marine
Fisheries Division, Durham, NH 03824, USA.
Acoustic techniques, videography, and quadrat sampling were used to characterize several subtidal oyster reefs in
the Great Bay Estuary in New Hampshire and to compare their effectiveness, with the long-term goal being a
general protocol for reef mapping and monitoring. The acoustic techniques consisted of a hull-mounted Klein 5000
sidescan sonar system, a Knudsen 320P, 50-200 KHz dual frequency sounder, and a Navitronic Seadig 210 KHz
multi-channel sounder. Videography was conducted by systematically imaging each of 40 sampling cells in a grid
covering the approximate area of each reef. A single drop was made in each cell and a 5 to 10-s recording made of a
0.25 m2 area. A still image was produced for each of the 40 cells and all were combined into a photomontage that
revealed the approximate boundaries of the reef. Five to ten cells on each reef were randomly chosen and sampled
by divers using a 0.25 m2 quadrat; all live oysters were measured (shell height) to nearest mm using calipers. The
same quadrat area was also video-imaged. Preliminary analyses showed good correlations between the quadrat
counts and counts made directly from the video images only when densities were relatively low. Preliminary
analysis of the acoustics data indicated that reef boundaries could readily be mapped, and some differences possibly
related to shell density variations also detected. Overall, our results to date indicate that acoustic techniques
generally can delimit the boundaries of oyster reefs, as has been demonstrated in other studies. The potential for
acoustically inferring other reef characteristics (e.g. oyster densities), however, remains to be fully tested.
Videography also may be a powerful and relatively inexpensive tool for detailed reef mapping, including inferring
oyster densities and perhaps other characteristics.
Fiddler crab fitness: exercise and the cost of sex
Bengt J. Allen* and Jeffrey S. Levinton. Department of Ecology and Evolution, State University of New York, Stony
Brook, NY 11794, USA.
Fiddler crabs (genus Uca) exhibit extreme sexual dimorphism. The major claw comprises as much as 40% of the
male’s total body mass. Male’s with larger claws have an advantage in male-male competition, and are often
preferentially chosen as mates by females. Sexually selected characters may have associated costs, and it has been
suggested that the presence of the major claw might result in reduced foraging efficiency or increased risk of
predation for male crabs. Empirical support for these hypotheses, however, has been mixed. Using a simple measure
of performance efficiency, we tested the hypothesis that carrying the major claw represents an energetic cost to male
fiddler crabs.
We ran male sand fiddler crabs (Uca pugilator) on a motorized treadmill at a constant velocity, and measured time
to fatigue. Crabs with a major claw tired significantly sooner than crabs without a major claw (which can be
autotomized by the crab, and subsequently regenerated). Similarly, crabs carrying added weight tired sooner than
crabs without an additional load. The relationship between weight and endurance is complex, and there appears to be
a threshold weight associated with a marked decrease in crab performance. Crabs without a major claw crossed a
threshold of endurance and could run for much longer periods of time. There also appears to be a postural cost
associated with holding the claw away from the body. Our results suggest that claw size must be a reliable indicator
of male fiddler crab quality, as only crabs in good condition would counteract the energetic cost of bearing such a
large major claw.
Effects of hemichordate bioturbation on infaunal abundance and composition on a sandflat in southeastern
North Carolina
Troy Alphin,* Martin Posey, and David Wells. University of North Carolina at Wilmington, Center for Marine
Science, Wilmington, NC, USA.
The acorn worms, Balanoglossus and Saccoglossus, are large infaunal bioturbators, commonly found on sandflats in
southeastern North Carolina. These organisms deposit large amounts of sediment on the substrate surface in the
form of castings. In addition to the physical disturbance of sediment deposition and reworking caused by these
organisms, they also produce halo-organic compounds that have been proposed to act as a predator deterrent. We
present here the results of two studies evaluating the infaunal community impacts of high-density assemblages of
these infaunal bioturbators. The first study evaluated functional guild responses through defaunation and recovery
experiments as well as seasonal comparisons of the ambient community within the acorn worm assemblage
compared to adjacent areas with few of these bioturbators present. The second study focused on recruitment (both
immigration of adults and larval recruits) into the hemichordate assemblage compared to adjacent areas, as well as
targeting the effects of halogenated compounds on infauna through chemical infusion experiments.
De-coupling of top-down and bottom-up regulation due to hypoxic disturbance in Narragansett Bay, Rhode
Island
Andrew H. Altieri* and Jon D. Witman. Department. of Ecology and Evolutionary Biology, Brown University,
Providence, RI 02912, USA; e-mail andrew_altieri@brown.edu.
Predation pressure (i.e. top-down control) has been shown to control the lower depth distribution of the blue mussel
(Mytilus edulis) in many areas of the world. Moreover, in many of these systems the distribution and abundance of
many predator species are trophically dependent on availability of the highly productive mussels (i.e. bottom-up
control). The opportunity to test the generality of these interactions arose in the spring of 2000, when a pulse of blue
mussel recruitment covered large areas (over 7,200 m2) of the benthos in Narragansett Bay to depths exceeding 7 m.
The following spring we initiated a series of surveys and experiments at 3-16 subtidal sites on a scale of tens of
kilometers designed to elucidate the relative importance of top-down and bottom-up interactions between blue
mussels and their predators, with particular attention to the seastar Asterias forbesi. Here we present several lines of
evidence that suggest blue mussels did exert strong bottom-up control of predator distribution and abundance as
predicted by previous studies. However, during the period of our study we observed a massive die-off in the blue
mussel population of Narragansett Bay that appeared to be of a strong and pervasive abiotic origin. Our results
suggest that an intense period of oxygen depletion (hypoxia) in Narragansett Bay waters was responsible for this
control of the blue mussel populations. In sum, it appears that while blue mussels can play an important role in the
bottom-up structuring of the benthic community in Narragansett Bay, environmental stress in the form of hypoxic
disturbance, rather than predation, drives the dynamics of the blue mussel population.
Effects of disturbance on invasion success in marine communities
Safra Altman,* Jeffrey Terwin, and Robert Whitlatch. Department of Marine Sciences, University of Connecticut,
Avery Point, 06340, USA.
Introductions of non-indigenous species have resulted in many ecological problems including the alteration of
ecosystems, reduction of biodiversity, and decline of commercially important species. The question of how
disturbance affects invasibility has been examined through theoretical and correlative terrestrial studies. While
theory repeatedly predicts that increased disturbance leads to increased invader success, results from empirical
studies do not always support theory. The link between disturbance and potential invasion has rarely been studied in
the marine environment where dominance hierarchies, dynamics of larval supply, and resource acquisition may
differ greatly from terrestrial systems. In this study, marine fouling communities of Long Island Sound were used as
an experimental system to assess the effect of mechanical disturbance on invasion success. Experiments consisted of
manipulating disturbance in fouling communities that were grown on 100cm2 PVC panels. Treatments began after a
five-week development period, when fouling communities covered 100% of the possible primary substrate.
Disturbance treatments were characterized by frequency (single, biweekly, monthly) and magnitude ( 20%, 48%,
80%). Disturbance was created by removing all organisms from a randomly distributed area corresponding to
treatment value and thus providing primary substrate, a limited resource. Frequency and magnitude of disturbance
had a significant effect on both natives and invaders, although their responses to these factors differed. The impact
of disturbance treatments was significantly different from the control for natives and invaders in the single and
biweekly frequencies as well as the 20% and 80% treatments. The direction of deviation from the control
demonstrates a positive effect of disturbance on invaders coupled with a negative effect on natives. Disturbance, by
creating available space, may facilitate the success of invasive species in subtidal fouling communities.
Scientific diving
American Academy of Underwater Sciences. 430 Nahant Road, Nahant, MA 01908, USA; telephone (781) 55817370 x 334; fax (781) 581-6076; e-mail aaus@neu.edu; URL http://www.aaus.org.
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The AAUS has been serving the scientific diving community for over 20 years.
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diving programs. These standards were developed and written by the AAUS by compiling the policies set forth in
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scientific diving.
Are we chronically underestimating the abundance of lobster postlarvae?
Eric R. Annis,* Ruth Howell, and Robert S. Steneck. Darling Marine Center, 193 Clark’s Cove Rd., Walpole,
Maine 04573 USA.
Larval abundance drives the abundance of the American lobster, Homarus americanus. To understand the pelagic to
benthic coupling of this species we need quantify the abundance of settlement-competent postlarvae. Lobster
postlarvae were thought to reside primarily in surface waters, and past studies using plankton net samples estimate
75-95% of the population occurs in the top meter of the water column. Accordingly, most research on the
distribution and abundance of postlarvae has been based on surface samples. We examined the vertical distribution
of postlarvae using direct observation of individuals in situ with SCUBA to determine the proportion of time
postlarvae spend within our normal plankton net sampling depth (0-0.5m). Our results indicate that proportion of
the population at the surface may be considerably lower than previous estimates with individual postlarvae spending
only 35% and 50% of the time in the top 0.5m and 1.0m respectively. The proportion of the postlarval population
represented in surface samples is critical to estimates of total abundance which are used to determine distribution
patterns, and estimates of production, mortality, and percent settling to the benthos. Our findings indicate that fewer
postlarvae are represented in surface samples than previously thought and suggest that estimates of total abundance
and subsequent calculations may be in need of reevaluation.
The coral that dies beneath the waves: species turnover on Caribbean reefs during the last 3,000 years
R. B. Aronson,1* W. F. Precht,2 I. G. Macintyre,3 T. J. T. Murdoch,1 and C. M. Wapnick.1 1Dauphin Island Sea
Lab, 101 Bienville Boulevard, Dauphin Island, AL 36528, USA; 2Ecological Sciences Program, PBS&J, 2001 NW
107th Avenue, Miami, FL 33172, USA; 3Department of Paleobiology, Smithsonian Institution, Washington, DC
20560, USA.
Most ecologists suspect that the ongoing degradation of Caribbean reefs is unprecedented on a millennial time scale.
If this surmise is correct, then the spatial extent of species turnover must have increased greatly, from localized areas
of coral mortality and species replacement before the late 1970s to recent changes in biotic composition that
transcend reefs and even reef systems. Analysis of 36 reef cores, extracted according to a hierarchical sampling
design from 20 stations in a 375-km2 area of the central shelf lagoon of Belize, showed that the staghorn coral
Acropora cervicornis dominated continuously for at least the last 3,000 yr. The lettuce coral Agaricia tenuifolia
occasionally grew in small patches until the late 1980s. Within a decade, Ac. cervicornis was virtually eliminated by
white-band disease and Ag. tenuifolia recruited to and grew on the dead coral branches. The scale of species
turnover increased from tens of square meters or less to hundreds of square kilometers or more. Likewise, during the
1970s much of the open space on fore reefs in Jamaica, Belize, St. Croix, Florida and elsewhere was covered by
living populations of Ac. cervicornis interrupted by damselfish territories and other small areas of dead Ac.
cervicornis covered with fleshy and filamentous algae. Macroalgae now predominate because the scale of mortality
of Ac. cervicornis and its replacement by algae has increased enormously. The expanding scale of species turnover
events is rooted in the accelerating pace of ecological change at the regional level.
Green crab (Carcinus maenas) situation in the southeastern Gulf of St. Lawrence, Canada: the Prince
Edward Island situation
Dominique Audet,1* Gilles Miron,1 and Mikio Moriyasu.2 1Département de biologie, Université de Moncton,
Moncton, N.B., E1A 3E9, Canada; 2Department of Fisheries and Oceans Gulf region, Moncton, N.B., E1C 9B6,
Canada.
The green crab Carcinus maenas was accidentally introduced on the eastern coast of the United States in the 19th
century. It has since migrated northward from New Jersey and was officially observed off the coast of Prince
Edward Island in 1998. A two year field project was conducted from June to November 2000 and from May to
December 2001 on the southeast coast of P.E.I. to characterise the demographic profile and life cycle of C. maenas
at the northern end of its range on this side of the Atlantic. Bated eel traps were used as fishing gear. Fyke nets and
juvenile collectors were also deployed to capture crabs. Results obtained will be shared to describe seasonal
variations of various population characteristics (e.g. seasonal dynamics of cohorts, size, sex ratio). The moment of
different life cycle events such as period of molting, copulation and egg laying were also established. In the south of
the St. Lawrence Gulf, crabs bearing eggs occurs from July to November. The peak last two weeks at the beginning
of July. Water temperature varied between 16.5 and 20.0°C at that time of the year. Mature males are molting from
June to December, but mainly in July before copulation, which begins in August just after larvae are released. In
general, life history events of C. maenas seems to occur slightly later in P.E. I. than what is observed in Maine. The
arrival of C. maenas in P.E.I. is of particular concern to the shellfish culture industries and commercial inshore clam
fishers. Its interactions with other coastal species may also have a great ecological impact. The 1998 incursion of
C. maenas in P.E.I may represent the early stages of a booming population. The long-term status of the green crab
in the southeastern Gulf of St. Lawrence is, however, still uncertain.
Assessment and restoration of mangrove impacts: a case study from Grand Cayman, B.W.I.
Timothy Austin,1 Kirsten Luke,1 Beth Zimmer,2* Adam Gelber,2 Martin Heaney,3 William Precht,2 Mark Henry,2
and Cindy Savage.4 1Department of Environment, P.O. Box 486 GT, Grand Cayman, Cayman Islands B.W.I.;
2
PBS&J, 2001 N.W. 107th Ave., Miami, FL 33172, USA; 3PBS&J, 1880 South Dairy Ashford Street, Suite 300,
Houston TX 77077, USA; 4Caribbean Utilities Company, P.O. Box 38 GT, Grand Cayman, Cayman Islands B.W.I.
Coastal mangrove ecosystems are among the most productive systems in the tropics. Mangroves provide a variety
of intrinsic ecological benefits including the nursery grounds for a number of commercially important finfish and
shellfish. Accordingly, mangroves form an important part of the economic resource base of the Caribbean. In
addition, they are important as geologic agents, providing a coastal buffer against waves and storms. Although this
ecosystem is highly resilient in the face of natural stressors, they are extremely vulnerable to a number
anthropogenic impacts. To this end it is imperative to protect this resource and where possible to restore disturbed
areas. At Rum Point in northeastern Grand Cayman, unavoidable impacts related to the construction of the Islands
power infrastructure consumed an area of red and mixed mangrove habitat totalling 0.24 and 0.68 acres,
respectively. An assessment of these impacts, including a GPS base map was prepared detailing the type and
amount of mangrove loss. A restoration plan was developed in accordance with this assessment. The first phase of
restoration included the physical grading of the site to appropriate mangrove elevations and was completed within a
few weeks of the initial impacts. Phase two included the collection of some 5,500 red mangrove propagules that
were planted in pots, and reared in a nursery for about six weeks until leaves emerged. These were planted on 0.5 m
spacing throughout the 0.92-acre area. Follow-up monitoring shows this planting effort to be extremely successful
with <14% prop mortality in the three months since transplantation. It is anticipated that as these red mangroves
become well established, natural recruitment of black mangroves will occur in areas of slightly higher elevation
and/or in areas of higher soil salinity. A long-term monitoring effort is underway to evaluate the efficacy of this
restoration effort over time.
Physical constraints on zonation patterns of the barnacle Chthamalus fragilis
K. Aveni-Deforge* and D. S. Wethey. Department of Biological Sciences, University of South Carolina, Columbia,
USA.
Zonation patterns in the rocky intertidal are linked to microclimates. The upper distribution limits of many species
in the intertidal are determined by intolerance to the microclimate conditions rather than absolute tidal height. The
barnacle Chthamalus fragilis is common to the rock jetties of South Carolina, where its upper distribution limit
changes as a function of slope and azimuth of its substrate. Small, temperature data loggers were glued to the rocks
at the upper distribution limits of Chthamalus aggregations, and 10 cm beneath the upper limit, amid dense
populations. Temperature was recorded at 15 minute intervals for sites with a variety of slopes and azimuths. Adult
survival was determined by comparing daily photographs taken of the regions surrounding the data loggers. Larval
recruitment and survival was measured on rocks that had been cleared of adults by comparing daily photographs of
permanent transects adjacent to temperature loggers. Temperatures as high as 45C were observed at rock surfaces
just above the upper distribution limit of Chthamalus several times over the course of the summer. Data loggers
within the barnacle zones commonly recorded temperatures 5C lower than those at the upper distribution limits.
Mortality and growth of early recruits varied daily as a function of recent exposure to high temperature conditions.
The mortality of adults was strongly affected by the most extreme rock temperatures, and repeated exposure to
relative extreme temperatures.
Trophic interactions between bacteria and meiofauna in the Gulf of Mexico deep-sea: sink or link for carbon
secondary production?
Jeff Baguley,1* Paul Montagna,1 Larry Hyde,1 Jody Deming,2 and Shelly Carpenter.2 1University of Texas Marine
Science Institute, 750 Channel View Drive, Port Aransas, Texas, 78373, USA. 2University of Washington, School of
Oceanography, Seattle, WA, 98195-7940, USA.
The structure and function of deep-sea benthos in the northern Gulf of Mexico is currently being investigated in a
large interdisciplinary program. Bacterial and meiofaunal biomass dominate in these sediments and may form the
basis of the abyssal food web. The goal of the current project was to determine if meiofaunal grazing rates were in
balance with heterotrophic, aerobic bacterial production in the deep-sea. Incubations of top 1-cm samples from four
stations at in situ temperature and pressure were performed using methyl 3H-Thymidine to measure rates.
Meiofaunal grazing rates, meiofaunal biomass, and bacterial biomass decreased with depth from 700 m to 2700 m,
but bacterial production increased. Meiofaunal grazing rates increased as a functional response to increasing
bacterial biomass. However, an inverse relationship occurred between bacterial production rates and meiofaunal
grazing rates, indicating a competitive interaction for available resources or simply a trend with depth. Meiofaunal
grazing rates were low, indicating bacterial production exceeds meiofaunal consumption. Heterotrophic, aerobic
bacteria may therefore not be a significant link to higher trophic levels in deep-sea sediments. Rather, they may
function as a sink for secondarily produced carbon and may be able to out compete higher trophic levels for
particulate and dissolved organic matter flux to the deep-sea floor.
Brachyuran megalopal availability in the Lower Cape Fear River estuary
Russell W. Barbour,* Martin H. Posey, Troy D. Alphin. Department of Biological Sciences, University of North
Carolina at Wilmington, Wilmington, NC 28403, USA.
Several species of brachyuran crabs live primarily in the estuary, but their larvae are exported to coastal waters for
development in the plankton and they must re-enter the estuary to occupy adult habitats. Recruitment/settlement is a
key aspect of larval ecology and is often crucial to determining the overall abundance of the adult population in a
given area. Juveniles of several of these crab species are often found most abundantly in oligohaline and
mesohaline waters when compared to the polyhaline or euhaline areas of the estuary. This raises the question as to
whether megalopae are using selective tidal steam transport in order to reach the mid-upper estuary or whether they
are settling preferentially in the euhaline or polyhaline region, and migrating upriver as early juveniles. The
question is particularly relevant for the more poorly studied small, river-dominated systems prevalent along the
southeastern coast of the United States. Our study involved the use of plankton tows taken during night flood tides
and larval collectors in adjacent shallows to look at the issue of larval supply and transport to
mesohaline/oligohaline portions of the estuary. Sampling occurred in five-day windows around both the new and
full moons from mid-June to mid-October to target peak recruitment windows. Preliminary results indicate that
megalopae preferentially settle in euhaline and/or polyhaline regions of the estuary, although some megalopae do
reach oligohaline waters via tidal stream transport before settling. Thus, the higher numbers of juveniles found in
the mid-upper estuary may represent a combination of larval recruitment and juvenile migration.
Ecophysiology of Dictyota spp. on Conch Reef, Florida Keys
K. S. Beach,1* L. J. Walters,2 and H. B. Borgeas.1 1Department of Biology, The University of Tampa, Tampa FL
33606, USA; 2Department of Biology, University of Central Florida, Orlando FL, 32816, USA.
Over the last two decades macroalgae have become a dominant component of reefs in the Florida Keys. Between
1994 and 2001 the brown algal genus Dictyota occupied as much as 70% of the benthos with biomass as high as 730
g (fw) m-2. Dictyota cover varied over time with fluctuations in storm activity and over depth with decreased cover
with increased depth (7 to 30 m). Dictyota spp. were found growing as free-standing individuals and epiphytically
on hard corals , soft corals , sponges and other macroalgae on Conch Reef. In order to gain insight into the factors
influencing productivity of this weedy macroalga, the physiology and pigmentation of D. menstrualis and D.
pulchella were examined 1) for free-standing individuals from three depths (7, 21 and 30 m) and 2) for Dictyota
individuals epiphytic on various hosts. Constraints on the breadth of the photoacclimation response limited
productivity with decreased irradiance with increased depth. Both saturation and compensation irradiance
thresholds did not vary with depth resulting in deeper growing specimens experiencing a decreased photoperiod
during which irradiance was saturating (Hsat). Variations in productivity as measured in situ by chlorophyll
fluorescence were in part explained by the type of host Dictyota epiphytes were growing upon. Dictyota epiphytic
on sponge hosts had higher rates of electron transport (ETR) than Dictyota that was both free standing and epiphytic
on other macroalgae as judged by rapid light curves. Proximity to certain benthic invertebrates may provide
nutrients to Dictyota that may otherwise be limiting to productivity. From this work it is clear that both large and
small scale variations in physical environment have significant impacts on primary productivity on algal dominated
reef systems.
Assessing larval dispersal using trace element concentrations in mytilid
larval shells
Bonnie Becker,1 Lisa Levin,1* Pat McMillan,1 Joel Fodrie,1 John Largier,1 Shelly Walther,1 and Claudio DiBacco.2
1
Integrative Oceanography Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0218, USA; 2Biology
Department, Woods Hole Oceanographic Institute, Woods Hole, MA 02543, USA; e-mail llevin@ucsd.edu.
Using elemental fingerprinting, we are evaluating the sites of origin and larval trajectories of mytilid mussel recruits
in southern California. Analysis of trace metal composition of larval shells offers an opportunity to reconstruct the
environmental conditions and therefore the approximate trajectory the mussels experienced during planktonic
development. Key steps involve (1) defining the relationship of seawater T, S and metal concentration to shell
composition, (2) determining location-specific differences in shells of larvae and new recruits, and (3) documenting
temporal, ontogenetic and other vital effects on shell composition. Based on ICP-MS analyses, differences in
seawater chemistry have been detected among bay and coastal sites in southern California. Mytilid shell elemental
fingerprints derived from solution-based (ICP-OES) analyses yield differences by site of collection, species and
shell size. Ongoing, high resolution, fine scale (8-20 micron) analysis of shells (LA-ICP-MS) of outplanted larvae
and new recruits will allow reconstruction of larval dispersal trajectories and comparisons with predictions based on
a physical connectivity model created for the southern California bays and coastal zone. Ultimate goals are to assess
the extent of self-seeding and exchange between populations.
Invertebrate community structure in the Gulf of St. Lawrence: the effect of algal canopies on recruitment and
growth.
Chantale Bégin,* Ladd E. Johnson, and John H. Himmelman. Groupe Interuniversitaire de Recherches
Océanographiques du Québec, Université Laval, Pavillon Vachon, Cité Universitaire, Québec, G1K 7P4, Canada.
Macroalgae can play an important role in marine communities directly as a source of food and shelter and indirectly
by altering flow. The overall effect of an algal canopy on a benthic invertebrate community was examined in the
Mingan Archipelago both observationally and experimentally. First, invertebrates were sampled in the summer of
2001 in four different types of algal patches (Alaria esculenta, Agarum cribrosum, Desmarestia viridis and Ptilota
serrata) as well as in adjacent urchin barren zones. NMDS and ANOSIM detected significant differences in
invertebrate assemblages between all habitats. Alaria esculenta sheltered the most distinct invertebrate community,
dominated by the blue mussel Mytilus edulis. A manipulative experiment was then carried out with the two most
abundant algae (Alaria esculenta and Agarum cribrosum). The canopy was removed in June to examine the effects
on invertebrate recruitment and mussel growth. Ceramic tiles were placed in the experimental units (present,
removed, naturally absent) from late June to October. Recruitment onto the tiles varied significantly between
treatments, with Spirorbis borealis, hydrozoans and Mytilus edulis accounting for most of the differences between
habitats. Cages containing mussels (Mytilus edulis) were also placed in the field from early July to October, and
their growth varied significantly between treatments, being greater in the Agarum zone than the Alaria zone.
However mussel growth did not vary between presence or absence of a canopy for either algal zone. These results
show that distinct invertebrate assemblages are associated with these algae and suggest that algal canopies
significantly affect both growth and recruitment for several species.
Quarantined! Ecological ramifications of disease in the caribbean spiny lobster, Panulirus argus
Donald C. Behringer, Jr.,1* Mark J. Butler IV,1 and Jeffery D. Shields.2 1Department of Biological Sciences, Old
Dominion University, Norfolk, Virginia 23529, USA; 2Virginia Institute of Marine Science, College of William &
Mary, Gloucester Point, Virginia 23062, USA.
In 2000 we discovered a lethal virus (HLV-PA) infecting Caribbean spiny lobsters, Panulirus argus. It is the first
virus described for any lobster, and appears to alter the behavior and ecology of this species in fundamental ways.
The most remarkable change being in the social behavior of healthy individuals in response to diseased conspecifics.
Both field and laboratory data show nearly unilateral avoidance of infected lobsters by healthy conspecifics. We
have identified infected juvenile lobsters at 75% - 100% of the 14 nursery habitat sites that we have surveyed twice
a year (summer and winter) since 1999 in Florida Bay, adjacent to the middle and lower Florida Keys, USA. The
disease was prevalent in up to 40% of the juveniles at each site (mean = 8%). Disease prevalence is substantially
higher in the smallest size juveniles (<20mm CL), with a mean of 16% in that size class. Thus far, HLV-PA appears
limited to juvenile lobsters. In an initial survey of the adult population, primarily located along the reef tract of the
Keys, we (in collaboration with the Florida Marine Research Institute) sampled 860 adult lobsters and only 4
individuals (< 1%) presented visual signs of HLV-PA infection. Both of these estimates are based on late stage
infections, and therefore conservative since we have not yet developed a diagnostic tool to assess infection at earlier
stages. Initial transmission trials show the virus to be considerably pathogenic, with an infection rate of 90% (n=20,
control n=10) in initial challenge trials using injected hemolymph from infected donors and an infection rate of 40%
(n=25, control n=10) in oral ingestion (of infected tissue) trials. An intriguing epidemiological twist is that
commercial and recreational fishing activities for this economically valuable species potentially contribute to the
spread of the pathogen.
The effect of dynamic hypoxia on the movement patterns and depth distribution of adult blue crabs within a
highly eutrophic river
Geoffrey W. Bell,* David B. Eggleston, and Thomas G. Wolcott. Department of Marine, Earth, and Atmospheric
Sciences, North Carolina State University, Raleigh, NC 27695, USA.
Little is known about how periodic hypoxic intrusions into shallow, nearshore habitats influence local migration
patterns and trophic dynamics of mobile species such as the blue crab. Hypoxic upwelling events may cause direct
and indirect mortality of crabs, and alter trophic dynamics when crabs recolonize deeper water habitats during
relaxation of hypoxic events and increase consumption rates on slow-recovering infaunal prey. We used 1) a trawl
survey to determine how periodic hypoxic intrusions into nearshore habitats alter local abundance and distribution
patterns of blue crabs, and 2) biotelemetry techniques to monitor movement and feeding responses of individual
crabs to the spatiotemporal dynamics of water quality and local prey abundance. Results from the trawling study
indicate that: 1) the proportion of crabs collected in shallow habitats was greatest (i.e., crowding) during hypoxic
intrusions ( 90%), 2) crabs were seldom found below 2 mg DO/l, and 3) some crabs were found during pronounced
anoxia (0.3 mgDO/l). Biotelemetry results suggest that movement and feeding responses of free-ranging blue crabs
varies depending on the rate of negative DO change. For example, telemetered crabs that experienced rapid drops in
DO stopped feeding and moved to shallower, more oxygenated waters, however, crabs experiencing gradual
declines in DO remained in hypoxic water for up to 9 hr and actively fed. One of the six telemetered crabs that
encountered DO concentrations below 1 mg/l died. Our combined results suggest that although most crabs avoid
hypoxic water, some crabs may occupy near-anoxic waters, and that hypoxic upwelling can cause mortality of even
highly mobile species such as blue crabs. The local population-level consequences of hypoxia on the blue crab
remain unknown.
Seagrass dispersal: seeds, sediments, and serendipity
Susan S. Bell,1* Mark S. Fonseca,2 Margaret O. Hall,3 Kamille Hammerstrom,2 W. J. Kenworthy,2 P. Whitfield,2
and M. Finkbeiner.4 1Department of Biology, Univefsity of South Florida, Tampa, FL 33620-5200, USA;
2
NOS/NOAA, Center for Coastal Fisheries and Habitat Research, Beaufort NC 28516, USA; 3Florida Marine
Research Institute, Florida Fish and Wildlife Commission, St Petersburg, FL 33701, USA; 4NOAA Coastal Services
Center, Charleston, SC 29405, USA.
We studied the spatial distribution of the seagrass, Halophila decipiens, on the West Florida Shelf during summer of
1999 and 2000. Halophila decipiens is diminutive (2-3 cm blade length) and is only present typically from June
through October. An extensive rhizome system is lacking in this species and reappearance of seagrass beds is from
seed banks. We conducted underwater surveys of the seabed floor at selected sites ranging from 10-25m in depth
using a towed videocamera and GPS at the same locations in both years. From the video-transect information we
delineated the spatial distribution of Halophila decipiens over 1km x 1 km at each site. In 1999 the midshelf site,
unlike other study sites, had large areas of exposed hard bottom devoid of sediment. Macroalgae were the dominant
vegetation in these areas and Halophila decipiens was absent. In contrast, in 2000 when identical transects were
performed, Halophila decipiens, was commonly encountered. Additionally, in 2000, sediment covered about 85%
of the hard bottom area that was mapped in 1999. Because all Halophila decipiens die at the end of the growing
season and only a seed bank remains, the presence of seagrass in 2000 at the midshelf site must have been a result of
seeds transported into the location. Examination of sediment cores verified that Halophila decipiens seeds were
present (mean =1027/m2). We calculate the minimum distance that seeds moved to be 250m. This distance was
probably even greater and highly influenced by hurricane activity. While previous information suggests that seeds of
other seagrasses disperse but small distances from parent plants and clonal spreading is the main mechanism by
which seagrass expand over long distances, our results show this is clearly not the case for Halophila decipiens.
Gut passage times in penaeid shrimp: differences between field and laboratory measurements and relevance
to aquaculture
Jennifer Beseres1* and Robert Feller.1,2 1Marine Science Program, 2Department of Biological Sciences, University
of South Carolina, USA.
The global shrimp aquaculture industry has developed both for profit and to reduce harvest pressures on wild stocks.
However, improper feeding regimes and feed formulae have lead to problems with water quality due to nutrient
over-enrichment. Gut passage times (GPT, time from first ingestion of feed to first egestion) for juvenile
Litopenaeus setiferus, L. vannamei, and Farfantepenaeus aztecus were measured in field and laboratory experiments
using thirteen soy-based experimental aquaculture feeds with varying amounts of protein, fiber and lipid.
Fluorescent beads were mixed with the feeds to trace the digestion process. GPT was directly observed in
laboratory trials, while indirect methods were employed using field cages. Increased levels of protein in
experimental feeds did not lead to significantly increased GPTs. Laboratory measurements with individual shrimp
suggested that methods for determining gut passage times in the field were consistently but measurably biased.
These studies can be used to determine more appropriate feed formulations and feeding frequency schedules for
shrimp culture.
Seasonal changes in algal community structure at Togcha Bay and Pago Bay, Guam
Kevin P. Bevis,1* Patrick M. Erwin,1 Valerie J. Paul,2 and Robert W. Thacker.1 1Department of Biology, University
of Alabama at Birmingham, Birmingham, AL 35294, USA; 2University of Guam Marine Laboratory, UOG Station,
Mangilao, GU 96923, USA.
Algal community structure can be strongly affected by abiotic factors, including rainfall and wave action, as well as
biotic factors such as herbivory. As part of a long-term monitoring program, we measured cyanobacterial
abundance, macroalgal abundance, and nutrient availability at two reef flat locations on Guam, Pago Bay and
Togcha Bay, from April 1998 to June 2000. We obtained estimates of wave action, rainfall, and herbivore
abundance from other monitoring programs administered by the National Weather Service and the Guam
Department of Agriculture. We correlated the abundance of herbivorous fishes, rainfall, and wave action with algal
diversity and abundance using a multivariate analysis of similarity. The relative palatability of algal species
influences their responses to these variables, with herbivore-resistant blue-green algae dominating the community
when herbivorous fishes are abundant and more palatable macroalgae dominating the community when herbivorous
fishes are rare.
Using tropical macroalgae as indicators of environmental stress in seagrass habitats
Patrick Biber.* Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science,
4600 Rickenbacker Causeway, Miami, FL 33149, USA.
Macroalgae may be useful indicators of certain stressors, particularly nutrient enrichment, in seagrass habitats.
However, a full understanding of macroalgal seasonal and spatial dynamics in relation to abiotic factors, other than
nutrients, has not been undertaken to date in tropical systems. A comprehensive study in Biscayne Bay included
light, temperature, salinity, nutrients, and hydrodynamic transport as five major variables which may affect
distribution and abundance of three groups of macroalgae: seagrass epiphytes, drifting macroalgae, and calcareous
rhizophytic species (e.g. Halimeda, Penicillus). Light and temperature were found to be important variables
influencing the seasonal responses of all three groups. In the Bay, the spatial distribution of salinity and nutrients is
influenced by the highly managed hydrology of South Florida and is therefore spatially heterogeneous, with a
gradient of these two factors across the Bay. Low salinity levels during the wet season were found to be responsible
for the exclusion of intolerant species, primarily calcareous-encrusting epiphytes and the rhizophytic algae.
Elevated nitrogen levels may have enhanced the formation of blooms of drift algae during favorable seasonal
periods (spring and early summer). Tidal currents also vary in magnitude throughout the Bay. For drifting
macroalgae, this hydrodynamic regime may influence the spatial distribution of biomass, with the western shores of
Biscayne Bay acting as a "sink" for algae transported into, and from sources within, the Bay. The macroalgal
community changes both seasonally (with temperature and light) and spatially (with salinity, nutrients and flow)
within Biscayne Bay. The presence of blooms of drift algae was correlated to not only nutrients, but also salinity,
flow, and temperature. In considering the use of drifting macroalgae as indicators of environmental stress for
tropical seagrasses, numerous variables may need to be considered.
Life on the edge: nocturnal prey emergence may lower energy transfer at the coral reef-seagrass interface
Derrick Blackmon* and John F. Valentine. University of South Alabama and Dauphin Island Sea Lab, 101 Bienville
Dr., Dauphin Island, AL 36528, USA.
Nocturnally foraging, lower order coral reef consumers (specifically, omnivorous fish and larger predatory
invertebrates), are thought to feed heavily on macroinvertebrates found in surrounding seagrass habitats. Despite intense
feeding within these vegetated habitats, the density of prey is not depleted, suggesting that either the prey productivity in
areas near the reef are great or that these prey have as yet unrecognized mechanisms that allow them to escape
nocturnally foraging predators. Among the possible explanations for the persistence of prey in these nearby habitats is
that at least some prey (e.g., crustaceans and polychaetes) are escaping prior to commencement of predator nocturnal
migrations via nightly post-settlement dispersal.
Using a combination of diver plankton tows and emergence and settlement traps, we provide preliminary evidence that,
in fact, the nocturnal movement of prey at the seagrass-coral reef interface is great. Diver plankton tows taken over
seagrass beds near the reef and 60m away from the reef, collected 5-100 % more invertebrates in near bottom waters at
night versus during the day, and that 2-5 times more invertebrates were captured near the reef versus over the seagrass
bed 60m away. Both emergence and settlement traps placed, at these same locations, collected more invertebrates over
seagrasses near versus 60m away from the reef. These results suggest that future studies of food web interactions at the
coral reef-seagrass interface should incorporate the nocturnal foraging patterns of predators and the escape behaviors of
their prey. Future work will attempt to identify the factors that trigger this nightly re-dispersal.
Distribution of benthic primary production in the Suwannee River estuary, Florida, USA
Erin L. Bledsoe,* Christina E. Jett, Karen A. Donnelly, and Edward J. Phlips. Department of Fisheries and Aquatic
Sciences, University of Florida, 7922 NW 71st Street, Gainesville, FL 32653, USA; e-mail spider4@ufl.edu.
Like many estuaries subject to major riverine inputs, the ecology of the Suwannee River Estuary is closely tied to
the water quality characteristics of the Suwannee River. Nutrients entering the estuary from the river support
primary production (i.e., growth of phytoplankton, benthic algae, epiphytes and rooted plants), but in excess can also
lead to significant environmental problems like algae blooms. Benthic macroalgae and submerged aquatic plant
communities of the Suwannee River Estuary were surveyed in 2000 and 2001 as part of a larger study examining the
impact of nutrient loading on water column primary production. The results of this survey demonstrate that both can
be major contributors to the standing crop of primary producers within the region, and therefore may serve as
indicators of change in nutrient loading and water flow. Benthic biomass in the form of Enteromorpha spp.,
Polysiphonia spp. and Ulva lactuca. began accumulating on the shallow oyster reefs and mud flats near the mouth of
the Suwannee River in late fall and peaked during the winter months. At this time the typical blackwater flow of the
river was nearly colorless and turbidity was low, which dramatically increased light availability as secchi depth
increased from 1.5 to 4.0 m in this region. This algal growth gave way to another bloom in the spring, which
included Ectocarpus spp., Gracilaria spp., Laurencia spp. and U. lactuca. Generally these species were not
attached but drifting in large mats. These types of benthic algal blooms have not been previously recorded and it is
unknown as to the frequency and magnitude of these events. Chlorophyll a values were also obtained from
sediment surface samples, indicating that benthic microflora may also contribute significantly to primary production
in the estuary.
Age determination in high latitude crustaceans: the lipofuscin approach
B. A. Bluhm,1* T. C. Shirley,2 T. Brey,3 M. Klages.3 1School of Fisheries and Ocean Sciences, Institute of Marine
Science, 245 O’Neill Bld., Fairbanks, AK 99775, USA; 2School of Fisheries and Ocean Sciences, Juneau Center,
210 Anderson Bld., 11120 Glacier Highway, Juneau, AK 99801, USA; 3Alfred-Wegener-Institute for Polar and
Marine Research, Columbusstrasse, 27515 Bremerhaven, Germany
Determination of age in long-lived Crustacea is often hindered by the lack of appropriate methods for age
determination. This presentation shows results from the use of the autofluorescent pigment lipofuscin as an age
marker in an Antarctic shrimp and a lysianassoid amphipod (funded by German Science Foundation) as well as
preliminary results from the commercially important brachyuran Chionoecetes opilio from the Bering Sea (funded
by Alaska Dept. of Fish & Game). Resin brain sections were digitally recorded by confocal microscopy and the
pigment was subsequently quantified from the images. A modal progression analysis of the lipofuscin concentrationfrequency distribution revealed 8 and 5 regularly-spaced modes (assumed to reflect age classes) for the shrimp and
the amphipod, respectively. The average yearly pigment accumulation rates were nearly linear. Pigment
concentrations were lower in these polar species than in temperate or subtropical crustaceans investigated.
Reconfiguration in intertidal Chondrus crispus Stackhouse
Michael L. Boller* and Emily Carrington. Department of Biological Sciences, University of Rhode Island, 100
Flagg Rd., Kingston, RI 02881, USA.
Reconfiguration with the passing of a crashing wave allows an intertidal alga to reduce drag by exposing a smaller
projected area to flow. This phenomenon manifests itself as a change in the exponent to which water velocity is
proportional to drag (the Vogel number). While it is intuitive that objects that are less stiff easily reconfigure in
flow, little work has been done to quantify how variability in stiffness will influence the drag of an organism in
flow. Chondrus crispus was used as a model organism to study the effects of stiffness on drag. Because C. crispus
is effectively a very complex beam, Young’s modulus of the tissue, the cross-sectional area and shape, the length of
the beam, and application of the force will determine the degree to which an individual will reconfigure. Drag and
reconfiguration were measured on individual thalli at a range of water velocities. Speed specific drag was plotted
against water velocity to determine the Vogel number. Material properties of each alga were determined on a
tensometer and morphology was characterized. The relationships among thallus morphology, material properties,
and Vogel number will be discussed.
Fragments of Dictyota: growth, generation forces and entanglement/attachment to reef organisms in the
Florida Keys
Heidi B. Borgeas,1* Linda J. Walters,2 Kevin S. Beach,1 Laura Wick.2 1University of Tampa, Tampa, FL 33606,
USA; 2University of Central Florida, Orlando, FL 32816, USA.
Over the past decade, the brown alga Dictyota has become one of the dominant species on the Florida Keys reef
tract and thus, may have a huge impact on fish and sessile reef organisms. To date, our research has determined that
small fragments of D. menstrualis and D. pulchella are enormously successful at asexual reproduction via vegetative
fragmentation. Greater than 60 % and 75% of fragments (4 or less dichotomies) survived and attached to sand
grains within 3 d for D. menstrualis and D. pulchella, respectively. We have also previously documented that reef
fish regularly generate small fragments and these fragments are very successful (>100% attach within 2 d). Here,
we expand on this research and discuss: 1) growth of fragments in laboratory and field, 2) forces required to
generate fragments, and 3) entanglement and attachment of fragments on other reef biota (corals, sponges,
macroalgae). During 8 d of laboratory and field trials, fragments more than doubled in size. The mean growth rate
of 4 dichotomy fragments of D. menstrualis was 0.15 mg/d and D. pulchella was 1.15 mg/d. When tested with a
water-pik, all tested individuals of Dictyota fragmented at 6.1 cm/s. Mean ± S.E. field flow rates during our August
2001 Aquarius mission were 15.5 ± 2.4 cm/s at 7 m and 6.5 ± 0.8 cm/s at 21 m. Dictyota fragments were given the
opportunity to attach 11 sessile reef organisms. Within 3 d, at least 25% of the fragments temporarily held in
contact with hosts using stainless wire permanently attached to the sponges Iotrochata birotulata, Aplysina
cauliformis, Niphates digitalis and Agelas wiedemyeri; the macroalgae D. menstrualis and Halimeda tuna; and the
corals and Briarium asbestinum. Attachment rarely occurred on Millipora alcicornis (fire coral), Eunicea mammosa
(soft coral), Gorgonia ventalina (sea fan), and Callyspongia vaginalis (sponge).
Macro-landscape similarities between North and South American salt marshes: an experimental approach
Alejandro Bortolus.* Ecology and Evolutionary Biology, Brown University, Providence, RI, USA; Consejo
Nacional de Investigaciones Cientificas y Tecnicas, Fundacion Antorchas, Argentina; e-mail Bortolus@Brown.edu.
For a long time, ecological works focused on many South American coastal environments were descriptive rather
than experimental. Thus, scientists assumed dogmatically a number of hypotheses conceived in other regions or
continents about what are the processes that regulate, maintain and shape those environments. Salt marshes are not
an exception. These environments are usually dominated by the same genus of organisms (e.g. Spartina, Salicornia,
Uca), and many times by the same species (e.g. Spartina alterniflora, Salicornia virginica). The amazing similarity
between the landscape of North and South American salt marshes largely favored the belief that they were shaped
by the same processes. New experimental evidences show that many of these processes are different. The identical
crab/plant spatial association in the high marshes of Argentina and USA is a good example. Within both regions (1)
crabs are highly dense underneath the plants, while within uncovered areas their density drops 2-3 times. (2) crabburrows literally draw the spatial distribution of plants, (3) crab density within bared areas was rise 2-3 times by
experimentally shading them with artificial covers, (4) crabs died dehydrated soon (~12-120 min) after been tethered
in bared areas while they survived underneath the shading and plant covers, (5) crabs were proved not to be
specifically looking for food but for shelter. In Argentinean marshes crab distribution is driven by heat stress during
the summer, while they are mainly inside their borrows and inactive during winter. However, USA marshes seem to
be affected by a combination of heat stress (summer) and predation (autumn/winter). Without the predation effect,
the pattern would not be the same because crabs re-populate the bared areas during the colder seasons. These
comparative experimental studies constitute an important theoretical framework that offers new evidences and
hypotheses helping to understand more accurately landscape similarities in a macro scale.
Spawning and developmental success of horseshoe crabs in Jamaica Bay, NY: a highly disturbed urban
estuary
Mark L. Botton,1* Robert E. Loveland,2 and Tomio Itow.3 1Fordham University, NY; 2Rutgers University, NJ;
3
Shizuoka University, Japan.
Jamaica Bay is a highly urbanized estuary that lies almost entirely within the boundaries of New York City
(Brooklyn and Queens). Over many decades, perturbations such as bulkheads and landfills have greatly reduced the
extent of natural beaches and marshes, while contaminants from industries, combined sewer overflows, and
municipal and airport runoff have adversely impacted beach sediment and water quality. As part of a multidisciplinary investigation of the restoration potential for Jamaica Bay beaches, we studied 12 sites for their
suitability as spawning habitat for horseshoe crabs (Limulus polyphemus). Based on morphometrics, the horseshoe
crab population in Jamaica Bay was similar to other estuaries in the middle Atlantic. Spawning within Jamaica Bay
was very patchy; sandy beach habitat was absent from the intertidal zone at 7 of the12 proposed restoration sites.
Horseshoe crabs spawned successfully at all 5 sites that had at least some patches of well-drained coarse substrate,
interspersed within larger stretches of disturbed shorelines. Eggs from Jamaica Bay were reared in the laboratory,
using sea water from Jamaica Bay and Delaware Bay (as a control). Similar percentages of eggs developed into first
instar (“trilobite”) larvae in both sources of water, and developmental abnormalities were very rare (ca. 1%). We
concluded that the abundance of horseshoe crabs in Jamaica Bay is limited by the availability of suitable spawning
habitat rather than by water quality.
Prey selection by the invasive shore crab Hemigrapsus sanguineus in southeastern Massachusetts
Paul E. Bourdeau.* Department of Ecology and Evolution, State University of New York at Stony Brook, Stony
Brook, NY, USA.
Prey selection and consumption of the recently-introduced Western Pacific shore crab, Hemigrapsus sanguineus (De
Haan), were investigated in laboratory experiments to assess the potential of the crab to alter New England (USA)
rocky intertidal ecosystems through predation on common molluscs and macroalgae. Male and female H.
sanguineus were collected from the rocky intertidal zone of two southeastern Massachusetts sites from May to
November 1998. Selection of mollusc prey was examined in relation to size and species. Crabs of three size classes
(12-18, 19-25, 26-31 mm carapace width) were offered three mollusc species: the mussel Mytilus edulis (L.), the
clam Mercenaria mercenaria (L.), and the snail Littorina littorea (L.). Equal numbers of prey from three size
classes of one mollusc species were offered concurrently to individual crabs to determine size selection and
consumption. In another set of experiments, equal numbers of small mussels and clams were offered simultaneously
to ascertain species selection. When presented with a range of prey sizes, crabs selected small sizes, large males
opening larger sizes than females and smaller males. Male crabs did not select mussels over clams. Females opened
only mussels, but ate flesh from previously opened clams. Neither male nor female crabs ate L. littorea. The
macroalgae Codium fragile (Suringar) ssp. tomentosoides (Goor), Enteromorpha (L.) spp., Chondrus crispus, Fucus
(L.) spp., and Ascophyllum nodossum (L.) were presented to individual crabs separately to determine consumption
rates and together to ascertain species preference. Crabs offered macroalgae in both multiple-choice and no-choice
feeding experiments preferred the green algae Codium fragile and Enteromorpha spp. H. sanguineus may be able to
alter natural prey populations in southeastern Massachusetts through selective predation.
Experimental evaluation of simulated herbivory and reduction of short shoot density on the extent of
Labyrinthula sp. infection in Thalassia testudinum
Justin W. Bowles.* Department of Biology, University of South Florida, Tampa, FL 33620-5200, USA.
A renewed interest in disease in the marine ecological literature has brought about an increased demand to better
understand the factors controlling disease transmission from one host to another, as well as to identify the ecological
significance of marine diseases. A marine slime mold, Labyrinthula, has been implicated as one of the factors
related to recent seagrass die-off in the USA.. Although several abiotic factors affecting the growth and
proliferation of this protist have been identified, biotic factors possibly affecting the extent of Labyrinthula infection
in turtle grass have not been experimentally investigated. A continuous monospecific bed of T. testudinum in
Charlotte Harbor, Florida (26°38.377’N, 82°09.505’W) has been chosen to investigate the effects of a reduction in
short shoot density and simulated herbivory on the extent of Labyrinthula infection in 4.0 m2 treatment plots. Short
shoot density will be reduced by severing 50% of the short shoots in the respective treatment plots beneath the
sediment, taking care not to damage the belowground rhizome network. The simulated herbivory treatment
approximates the feeding behavior of the green turtle, Chelonia mydas L., by clipping each T. testudinum short shoot
several centimeters above the apical meristem. Rhizomes at the perimeter of each treatment plot will be severed to
inhibit physiological integration among short shoots within and outside the treatment plots. A 0.5 m buffer zone
will be maintained around each plot by periodic clipping. The extent of Labyrinthula infection, short shoot density,
aboveground biomass, and productivity will be monitored in plots monthly. These data will be analyzed by a 4x4
randomized complete block (RCB) ANOVA and appropriate multiple comparison tests.
Desiccation resistance during the sea-to-land transition in the land hermit crab postlarva
Renae Brodie.* Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA.
The land hermit crab, Coenobita compressus, migrates from sea to land during the megalopal stage of postlarval
development. As the megalopa emerges onto land, it encounters a physical environment wholly different from that
of the sea. I investigated changes in C. compressus’ behavior and physiology that enable it to avoid desiccation on
land. In one experiment, I examined changes in rates of water loss before, during, and after megalopae were able to
settle on land to determine if their resistance to desiccation improved over time. I found that megalopae became
increasingly resistant to desiccation with age. In the second experiment, I exposed megalopae with and without
snail shells to relative humidities of 100, 92, 85, and 76% to determine if the shell would increase survival in the
lower humidity environments. Megalopae wearing shells were far more likely to survive the two lowest humidities
compared to their naked counterparts. Thus, behavioral and morphological enhancements to desiccation resistance
facilitate the land hermit crab’s transition to land.
Oyster predator-prey interactions: roles of different predators, seasonality, spatial variation and deterrents
Kenneth M. Brown,1* Gary Peterson,2 Mike McDonough,1 and Charles Ramcharan.1 1Department of Biological
Sciences, 2Coastal Ecology Institute, Louisiana State University, Baton Rouge, Louisiana, 70803, USA.
We conducted both small-scale laboratory and large-scale field experiments to study the roles of scent deterrents,
snail versus fish predators, estuarine versus coastal conditions, and seasonality in explaining mortality rates of
oysters (Crassostrea virginica). Preliminary laboratory experiments at the Grand Terre Marine Laboratory indicated
that small, single oysters, such as those planted on oyster leases, are extremely vulnerable to predation by black
drum (Pogonias cromis). Experiments in 20,000 L raceways indicated the scent of dead conspecific drum reduced
mortality rates from feeding fish by 46%, but variation among experimental trials was so large that the effect was
not significant. In large-scale field experiments at both estuarine and coastal locations in Barataria Bay, Louisiana,
we tested whether the scent of dead conspecifics would lower mortality rates to fish in separate experiments in the
fall and spring. Percent survival of oysters varied from 2 to 66%, and tended to be highest in the fall at the estuarine
site. Percent mortality caused by fish varied from 61-99%, and was highest in the spring at the coastal site. Percent
mortality caused by oyster drills (Stramonita haemastoma) varied from 1-38% and was highest in the fall at the
estuarine site. Scent significantly reduced fish feeding rates only at one of the sites, and then only for one of four
weeks in the fall experiment. We conclude that oyster drills and black drum pose serious predation risks for oysters,
both when seed oysters are planted in the fall, and before oysters are harvested in the spring. However, the scent of
dead conspecifics, considered a deterrent by local lease holders, does not seem effective in reducing mortality rates
caused by fish. We are currently investigating whether acoustic cues are effective deterrents for fish predation.
Inclusion of facilitation into ecological theory, models, and paradigms
John F. Bruno,1* John J. Stachowicz,2 Mark D. Bertness.3 1University of North Carolina, Chapel Hill, NC 275993300, USA; 2University of California, Davis, CA 95616, USA; 3Brown University, Providence, RI, USA 02912, USA.
Beginning with the origins of experimental marine ecology during the 1960s, up to the early 1990s, a vast majority
of ecological research was focused on the importance of competition, predation, disturbance, and physiological
stress. This pioneering work quickly led to the development of the theory and paradigms that are the foundation of
modern ecology. More recent investigations have uncovered the unanticipated yet striking influence of facilitation
on community structure. Research over the last ten years in a variety of habitats has clearly demonstrated the strong
effect of facilitation on population distributions and growth rates, species composition and diversity and even
landscape-scale community dynamics. We have incorporated facilitation into several influential community models.
In most cases updating ecological theories fundamentally changes their predictions and inevitably challenges some
of our most cherished paradigms. We also reevaluate some of the conservation strategies and priorities that were
based on these paradigms. For example we consider: (1) how the inclusion of facilitation affects predictions about
the factors that control species distributions and the size of the realized niche, (2) the expected relationship between
diversity and invasibility, and (3) the role of habitat-generating or modifying “competitive dominants” in enhancing
diversity. Overall, we suggest that a revision of ecological theory will lead to more realistic predictions and a more
accurate and inclusive understanding of natural communities.
Ecological impacts of artificial structures in estuaries
Fabio Bulleri.* Centre for Research on Ecological Impacts of Coastal Cities, Marine Laboratories A11, University
of Sydney, NSW 2006, Australia; e-mail fbulleri@bio.usyd.edu.au.
Habitat loss and fragmentation are major threats to biological diversity in coastal and estuarine systems. Although
some artificial structures, such as wharves, breakwaters and seawalls are largely replacing natural habitats in
urbanised coastal areas, their ecology did not receive much attention. It is fundamental to evaluate the level at
which artificial structures resemble natural habitats, in terms of patterns of distribution and abundance of organisms,
and to determine which are the processes acting to produce them. This study addresses this issue focusing on
intertidal assemblages on vertical rocky shores and seawalls in Sydney Harbour (NSW, Australia). The first
descriptive part of the study aimed to assess whether assemblages colonising artificial structures, at two tidal
heights, were different from those on nearby natural surfaces and whether these patterns were consistent in time and
space. The next step was to identify the ecological processes responsible for the observed patterns. Some
experiments were done to evaluate the role of recruitment and post-recruitment processes, habitat heterogeneity,
grazing and behaviour of invertebrates, in determining differences between natural and artificial structures. The
results showed that mid-shore assemblages on seawalls were different from those found on adjacent rocky shores,
consistently through time, while there were no differences between natural and artificial structures at lower levels on
the shore. Recruitment resulted to be the main process responsible for the occurrence of different assemblages on
seawalls and rocky shores, while the behaviour of a species of limpet, in terms of distance displaced and orientation
of the movement, did not change between structures. The results are discussed to establish whether the observed
differences between rocky shores and seawalls are ecologically relevant and to gain a general understanding of the
potential impact produced by the introduction of artificial habitats in marine environments.
The effects of bait-worm digging on intertidal benthic carbon remineralization in Maine
Tara N. Businski* and William G Ambrose, Jr. Bates College, Lewiston, ME, USA.
We examined the effects of bait-worm harvesting, a major sediment disturbance on mudflats in Maine, on benthic
remineralization and community structure. Aerobic respiration rates were determined by tracking oxygen depletion
over 12-24 hours from sealed sediment cores collected from dug and undug plots. We also determined macrofaunal
biomass and abundance in order to estimate the contribution of macrofauna to respiration and to quantify
community response to digging. Digging had no immediate effect on aerobic mineralization, but after one month
remineralization rate was 53% higher in dug than undug plots (mean ± SE, undug: 78.4 ± 6.5 mgC m-2 d-1; dug:
148.5 ± 23.5 mgC m-2 d-1). Two months after digging, the remineralization rate for dug plots had recovered to the
undug rate. The response in mineralization rate to digging could be caused by a community shift secondary to
digging or by increased organic matter deposition caused by the more pronounced topography of the dug site.
Everglades restoration and the effects of changing salinity on hard-bottom communities in Florida Bay
Mark J. Butler,* Scott Donahue, and Tom Dolan. Department of Biological Sciences, Old Dominion University,
Norfolk, VA, USA.
Proposed changes in water management within the Everglades are likely to profoundly alter the spatio-temporal
patterns of salinity within Florida Bay, with unknown consequences for hard-bottom communities. Although hardbottom habitat is limited primarily to southwestern Florida Bay, these habitats and the organisms they harbor are
important for understanding ecological linkages between the bay and the adjacent Florida Keys marine ecosystem.
We used laboratory experiments to assess lethal and sublethal effects of different salinity-temperature regimes on
prominent hard-bottom species, specifically Caribbean spiny lobster, five sponge species, and two species of
octocoral. We then incorporated these dynamics into a spatially-explicit individual-based lobster recruitment model
to predict the population-level consequences of salinity change on lobster recruitment. Our laboratory studies
indicate that early benthic juvenile spiny lobsters are intolerant of salinity change and experience high mortality,
especially at high summer temperatures. In contrast, the survival and growth of larger juvenile lobsters was
unaffected by salinity, although their movement rates initially increase then decline with altered salinity. The five
species of sponge that we tested varied in their tolerance to low salinity, although none survived the 15 ppt treatment
at winter temperatures and none survived any low salinity during high summer temperatures. Both species of
octocoral that we tested experienced 100% mortality at salinities below 35 ppt at all temperatures. Our model
simulations predict large impacts on lobster recruitment, especially when the indirect effects of habitat (i.e., sponge,
octocoral) loss are included in the model.
Nutrient enrichment and reduced grazing effects on epilithic turf on three Florida Coral reefs: its never that
simple
Justin E. Campbell* and Alina M. Szmant. Center for Marine Science, University of North Carolina at Wilmington,
5600 Marvin K. Moss Ln, Wilmington NC 28409, USA.
Coral reef degradation is often evidenced by phase-shifts in community structure in which thick epilithic turfs and
fleshy macroalgae overgrow reef substrate. Potential causes for such shifts are multiple, and include factors that
regulate rates of algal biomass production (bottom-up) as well as ones that affect biomass consumption (top-down:
grazing). This study examines the relative impact of nutrient availability and herbivory on the growth of benthic
epilithic turf algae. A two-way factorial field experiment was conducted on three reef sites in Key Largo, FL:
Pickles Reef (PI: low relief, offshore, strong Florida Current influence); Little Grecian (LG: high relief, protected
spur and groove, variable water quality); and Three Sisters (3S: low relief, mid-shore patch reef, usually turbid).
Moorings were used to suspend experimental substrates 2 m above the bottom, thus reducing access to grazing
(RG). Replicate substrates were secured on the reef near the mooring attachment. One set of 6 moorings were
fertilized with slow-release fertilizer (E); a second set was at ambient nutrient conditions (C). Effects of enrichment
and reduced grazing differed between sites in an unpredictable manner. E and RG at PI caused similar increases in
growth (3x) over controls, but there was no additive effect of E + RG as expected. At LG experimental treatments
and controls did not differ significantly. At 3S: E alone and RG alone each caused a 50 % but non-significant
increase in growth, while E+RG caused a 3x increase in growth over controls. Thus, the only clear evidence of
enrichment causing increased algal growth was at the most inshore station, the one hypothesized least likely to
exhibit such an effect. At the other two stations, grazing and enrichment had mixed and similar effects on algal
growth. These results suggest that anthropogenic nutrient enrichment is not widespread on Key Largo coral reefs.
Incipient speciation across a depth gradient in the tropical coral Favia fragum
D. B. Carlon1* and A. F. Budd.2 1Section of Evolution and Ecology, University of California, Davis, CA 95616,
USA; 2Department of Geoscience, University of Iowa, Iowa City, IA 52242, USA.
A few marine systems indicate that evolutionary divergence can occur despite gene flow. In the Bocas del Toro
region of Panama we found two morphotypes of the scleractinian coral Favia fragum: Morph 1 had corallites flush
with the coral surface, whereas Morph. 2 had tall corallites with deep valleys. A morphometric analysis of
costoseptae revealed discrete differences in morphology. Analysis of allozyme polymorphism at five loci revealed
strong divergence between morphotypes, however there was also genetic structure within morphotypes between
sites separated by 1-2 km. Hybridization and perhaps backcrossing are consistent with the genotypic data.
Morphotypes had different depth distributions. Morph 2 occurred at depths < 1 m, whereas Morph 1 was more
abundant below this depth. We discuss the role of adaptation to gradients in sedimentation in initiating this
divergence, and the roles of self-fertilization and limited dispersal in maintaining the imperfect reproductive
isolation between these two incipient species. This divergence adds a tropical coral to a list of marine examples,
including rocky intertidal snails (Littorina) and sponge-dwelling tropical shrimp (Synalpheus), that show the first
stage of speciation has occurred without geographical isolation.
Grow fast and avoid predators: why common periwinkles are most abundant in the low intertidal
Rose L. Carlson,1* Myra J. Shulman,1 and Julie C. Ellis.2 1Department of Ecology and Evolutionary Biology,
Cornell University, Ithaca, NY, USA; 2Department of Ecology and Evolutionary Biology, Brown University,
Providence, RI, USA.
The common periwinkle Littorina littorea is an abundant herbivore on the rocky shores of the North Atlantic. The
snail is found from the mid-intertidal (approximately 1.0 m above Mean Lower Low Water) to the shallow subtidal.
It is most abundant around 0.0 m MLLW and reaches densities of more than 600 snails m-2 at our study sites on
Appledore Island, ME. We investigated three non-mutually exclusive hypotheses that may explain the vertical
distribution of L. littorea: (1) interactions with crab predators, (2) preferential vertical migration, (3) relative growth
rates at different tidal heights. We found that the green crab, Carcinus maenas, overlaps in vertical distribution with
L. littorea, whereas Cancer borealis and C. irroratus are virtually absent above 0.0 m. Laboratory experiments
indicated that large C. maenas consume L. littorea significantly more often than do smaller C. maenas but less often
than all sizes of C. borealis. Although the green crab’s effect on the distribution and abundance of L. littorea
depends largely on crab size, its effect is likely smaller than that of C. borealis below 0.0 m. The snail’s vertical
migration patterns were investigated with a series of movement experiments. L. littorea were transplanted from 0.0
m to –1.5 m, 0.6 m, and back to 0.0 m. Twenty-four hours after release, the displaced snails had re-oriented towards
their height of origin. Further study is necessary, however, to determine whether this vertical migration pattern is a
homing response. The results of a month-long growth study further explained the marked abundance of snails at 0.0
m: juvenile snails caged at 0.0 m grew significantly more than snails caged at 0.75 m, 0.5 m, –1.5 m, or –3.0 m.
Growth of the soft-shelled clam, Mya arenaria, inside and outside a seagrass bed, Zostera marina, in Maquoit
Bay, Maine
Kevin L. Carpenter,* Kenneth J. Catalano, Elias N. Kassis, Janice K. Lewis, Kate R. Meltzer, William G. Ambrose,
Jr. Biology Department, Bates College, Lewiston, ME 04240, USA.
Our research examined the growth rates of the soft-shelled clam Mya arenaria inside and outside of a Zostera
marina seagrass bed in Maquoit Bay, Maine. We expected seagrass clams to show reduced growth rates due to
increased siphon nipping, reduced current velocities, and increased sedimentation within the grassbed compared to
the adjacent mudflat. Clams were collected haphazardly in September and October and aged by counting the
internal growth lines of the bisected condrophore. Seagrass covered 45% of the sediment surface and was
characterized by a mean shoot biomass (7.8 +/- 2.9 g), a root biomass (3.8 +/- 2.3 g), and a canopy height (31.4 +/4.9 cm). We found no significant difference in the growth rates and siphon weights of one and two year old clams
inside compared to outside the seagrass bed. Two year old clams had an average shell length (59.9 mm) which was
about two times longer than similarly aged clams in another Maine study (26.7 mm). Current velocity was 50%
slower in the grassbed compared to the adjacent mudflat, but this resulted in only a slightly significant (0.02%)
organic content difference (measured by LOI) between the two locations. There was no evidence that seagrass
influenced siphon nipping, indicating equal or no sublethal predation in the study sites or re-growth of nipped
siphons during a period of decreased predation. The fast growth of Maquoit Bay clams compared to other studies
suggests that there is high food availability throughout the site which minimizes the role of seagrass-reduced flow
rates for food delivery. The difference in growth between vegetated and unvegetated clams might be manifested in
older clams, however heavy commercial digging pressure made them difficult to find.
Scale-dependent effects of flow on coral reef primary production
Robert C. Carpenter.* Department of Biology, California State University, Northridge, CA 91330-8303, USA.
Coral reefs are among the most productive ecosystems in the ocean and it has become clear that water flow is central
to maintaining high rates of photosynthesis of reef primary producers. Rates of photosynthesis by reef algal turfs on
a spatial scale of 10's of cms are enhanced significantly by water motion. Preliminary data suggest that at the spatial
scale of the dominant organisms (cm to meters), boundary layer dynamics and mass transfer of materials to and from
the surfaces of organisms are critical in modulating rates of metabolism. The question remains whether flow exerts
the same important effects at the reef zone or community-wide spatial scale (10's to100's of meters). Preliminary
experiments in a larger flume using algal turf-covered substatum over a spatial scale of 4 meters along the axis of
flow suggest a similar positive relationship between photosynthesis and flowspeed as that demonstrated at smaller
scales. Estimates of net community primary production (NCCP) on the Kaneohe Bay barrier reef flat over 200
meters also indicate a positive relationship between flow and NCCP at this spatial scale, and the slope and strength
of the relationship is light-dependent. These preliminary results suggest that primary production of coral reef
communities is modulated by flow at all spatial scales and that primary production would be expected to vary
spatially as a function of hydrodynamic exposure, and temporally with tidal and wave height over the reef. Flowdependence may underlie some of the variation in rates of primary production that have been measured for coral
reefs throughout the tropics.
Ultrasonic telemetry of blue crab nocturnal ebb-tide transport near a barrier island inlet
Sarah D. Carr,1* Richard A. Tankersley,2 James L. Hench,1 Richard B. Forward, Jr.,3 and Richard A. Luettich, Jr.1
1
Institute of Marine Sciences, University of North Carolina at Chapel Hill; 2Department of Biological Sciences,
Florida Institute of Technology; 3Duke University Marine Laboratory.
Female blue crabs Callinectes sapidus migrate from low salinity areas of estuaries to high salinity regions near the
ocean to release their larvae. To characterize movement patterns during these spawning migrations, we used
ultrasonic telemetry to track ovigerous crabs near Beaufort Inlet, North Carolina, during July-August, 2001. Crabs
with mature egg masses were caught in the estuary during nocturnal ebb tides, tagged with ultrasonic transmitters,
and quickly released in the vicinity of Beaufort Inlet. Crabs were then tracked by boat using an ultrasonic receiver
and hydrophone. Current measurements were obtained while tracking using a boom-mounted shipboard ADCP.
Ten crabs were tagged during the spawning season. Tracking duration ranged from < 1 h to > 37 h. Four crabs
were tracked through the initial night ebb and displayed behaviors consistent with ebb-tide transport, a vertical
migration pattern in which an animal enters the water column during ebb tide and remains at the bottom during flood
tide. Crabs were transported seaward in the water column during nocturnal ebb tides and stopped moving shortly
(within 1 h) after the beginning of the subsequent flood tide. Although some movement was observed during flood
tides and diurnal ebb tides, this movement was of limited duration and distance and generally against prevailing
currents. One crab was tracked through a second nocturnal ebb tide. Seaward transport began again shortly after the
onset of the second nocturnal ebb and ended shortly (within 1 h) after the beginning of the subsequent flood. While
migrating on nocturnal ebb tides, crabs exhibited an unexpected “hopping” behavior, in which they alternated
between rapid transport in the water column and remaining stationary at the bottom. This hopping behavior resulted
in net transport less than a third of what would be predicted for passive particles transported by the currents near the
crabs.
Life history phases and the biomechanics of Chondrus crispus
E. Carrington,1* S. P. Grace,1 and T. Chopin.2 1Department of Biological Sciences, University of Rhode Island,
Kingston, RI, USA; 2Centre for Coastal Studies and Aquaculture, Department of Biology, University of New
Brunswick, Saint John, N.B., Canada.
The red alga Chondrus crispus Stackhouse alternates between two isomorphic life history phases which differ in
cell-wall phycocolloid composition. The carrageenans of the haploid gametophyte are the strong-gelling kappatype, while those of the tetrasporophyte are the non-gelling lambda-type. It has been long hypothesized that the
gametophyte is mechanically superior to the tetrasporophyte due to this difference in carrageenan composition, and
that such mechanical superiority contributes to the observed gametophytic dominance in many wave-swept
environments. To test these hypotheses, standard mechanical tests were performed on distal tissues of C. crispus
sampled from a range of environments in Narragansett Bay, Rhode Island, using a tensometer equipped with a video
extensometer. Life history phase was by far the most important determinant of mechanical properties, while
environmental factors had only modest influence (vertical distribution) or no effect (exposure); gametophyte distal
tissues were 43% stronger, 21% more extensible, and 21% stiffer than tetrasporophyte distal tissues. However, the
superior strength of gametophyte tissues was not evident at the stipe/holdfast junction (where breakage typically
occurs) and the two phases were equally susceptible to dislodgment by a given force. Thus the ecophysiological
role of carrageenans in C. crispus may not necessarily involve directly the provision of a structure to resist wave
action.
Physiological role of the brood pouch in Gulf pipefish, Syngnathus scovelli
Christi Cazalas,1* Jessica Rozelle,1* Charlyn Partridge,1* Jon Hemming,1,2 and Anne Boettcher.1 1Department of
Biological Sciences, University of South Alabama, Mobile, AL, USA; 2U.S. Fish and Wildlife Service, Panama City,
FL, USA.
The family, Syngnathidae, which includes seahorses and pipefish, is known for its unique role-reversed reproductive
strategy. The males have brood pouches in which eggs are fertilized and embryos are incubated prior to their release
as juveniles. The function of the brood pouch has been a question unanswered by researchers for nearly 100 years.
It has been speculated to play both an osmoregulatory role and a role in the protection and nutrition of developing
embryos. In order to better understand the function of the brood pouch, we are quantifying changes in the inorganic
and organic makeup of brood pouch fluid and blood of male gulf pipefish, Syngnathus scovelli, during their
brooding cycle. S. scovelli provide an ideal system in which to address this topic. They inhabit both fresh and
saltwater environments, are easily collected, and unlike many members of their family are not threatened through
over collection. This preliminary study focuses on baseline biomarkers for various stages of brooding in wild
freshwater, captive reared freshwater and captive reared saltwater males. Initial measurements include the
reproductive markers gonadosomatic (GSI) and hepatosomatic indices (HSI), the health indicator hematocrit, and
the nutrient indicators blood protein and glucose concentrations. Results indicate that both GSI and hematocrit
values decrease significantly through the brood cycle, however, no distinct patterns are seen for HSI. There also
appear to be biochemical changes associated with the brood cycle affecting both blood protein and glucose. This
study provides a foundation for broader-scale studies investigating the physiological and biochemical roles of the
brood pouch in this unique family.
A vision in white . . . and blue?: flexibility in stomatopod color communication associated with different light
environments
Alexander G. Cheroske* and Thomas W. Cronin. Department of Biological Sciences, University of Maryland,
Baltimore County, Baltimore, MD 21250 USA; e-mail cheroske@umbc.edu.
Animals often use signals to assess organismal conditions such as reproductive status or dominance. For species
occurring in heterogeneous light habitats, communication via color signaling can be problematic. Benthic marine
organisms receive light that is filtered by the overlying water and its constituents so that light at depth is less intense
and spectrally narrow. Mantis shrimp (or stomatopods) are colorful and fairly belligerent marine crustacea that
display conspicuous colored spots during intra- and interspecific interactions. Coupled with a complex color vision
system almost without rival, color signaling may have many functional roles in mantis shrimp behavior. This
signaling system may also be adaptable in both signal receiving (retina) and producing (body spots) structures in
response to different light conditions. Recently, research has shown that some species with wide depth ranges
(intertidal to >25 meters) in the superfamily Gonodactyloidea can modify parts of individual color receptors
(intrarhabdomal filters) in response to varying light stimuli. Mantis shrimp also can vary body coloration through
successive molts. In concert, retinal and body color changes may serve to preserve color signal function in variable
environments. To establish if this color flexibility remains in gonodactyloid stomatopods that only inhabit shallow
waters, experiments in aquaria with manipulated light treatments (broad spectrum, shallow vs. narrowly blue, deep)
were conducted with Neogonodactylus oerstedii over four months. After treatment, coloration of various body spots
was measured spectroradiometrically and color photoreceptor changes measured using microspectrophotometry.
Intrarhabdomal filters were similar from animals both treatments but the coloration of potential signaling areas were
different between ‘shallow’ and ‘deep’ environments. It seems that mantis shrimp species inhabiting shallow waters
may have lost flexibility of their color vision but may retain the ability to change body color. Stomatopod color
systems may be conservative in their adaptability as well as their functionality in variable photic environments.
The impact of sponge loss and recovery on the florida bay benthic community
Michael J. Childress.* Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA.
Previous studies have shown that large sponges are an important shelter resource to crabs and spiny lobsters. During
winter 1991-92 the sponge community of central Florida Bay suffered a mass mortality due to a cyanobacteria
bloom. Now, ten years later, I compare the recovery of the sponge community and its impact on crab and spiny
lobster density and den use patterns. Stinker (Ircinia fascioulata), sheepswool (Hippiospongia lachne), and
loggerhead (Spheciospongia vesparia) sponges were the first species to recover, while vase sponges (Ircinia
campana) have only returned to one region. Once these sponges reach approximately 20 cm diameter, crabs and
lobsters begin to use them as shelters. The impacted regions of Florida Bay have recovered a density of large
sponges approximately 25% of their pre-die off condition. However, this increase in large sponges is not
significantly related to an increase in the density of stone crabs (Menippe mercenaria) or spiny lobsters (Panulirus
argus). The presence of alternative protective structures such as solution holes, sea whips and hard corals and a shift
in the resident’s den use patterns ameliorated the impact of sponge shelter loss. Spider crabs (Mithrax
spinosissimus), however, prefer to shelter under sponges and have not yet recovered since the mass sponge
mortality. Thus, it appears that stone crabs and spiny lobsters are more likely to be limited by settlement habitat or
larval recruits than the absolute number of post-settlement shelters, whereas spider crabs may need sponges more as
a settlement substrate or a food resource than a source of protective shelter.
Discrimination of fish from mangroves and reefs using otolith microchemistry
Paul M. Chittaro.* Biology Department, University of Windsor, Windsor, Ontario, N9B-3P4, Canada; e-mail
chitta1@uwindsor.ca.
Mangroves are considered important nursery areas for coral reef fishes that provide shelter and food for juvenile
fish, which subsequently replenish nearby reefs. Unfortunately, little information exists regarding the relative
contribution of fish from mangroves to reef populations. The development of techniques that examine the
microchemical composition of fish otoliths has enabled informative studies addressing stock discrimination,
migratory history, and the identification of nursery areas. In order to evaluate the potential of otolith
microchemistry as a tool for assessing the relative importance of mangrove nursery areas, chemical signatures were
examined to see whether they could discriminate individual french grunts, Haemulon flavolineatum, held in
mangrove and reef sites in Bahamas and Belize.
H. flavolineatum were collected from three sites at both Great Exuma, Bahamas (two reef and one mangrove) and
Turneffe Atoll, Belize (one reef and two mangrove) during late May and early August 2001, respectively. Sites
within each location were separated by 0.25 - 7.1 km. At each site, 20-30 individuals were distributed among 4-5
enclosures and held for approximately 2 weeks in order to ensure that the outermost otolith layers were formed
while the fish was at the site. Otolith chemistry was determined for 15 randomly selected individuals from each site
using laser ablated inductively coupled plasma mass spectrometry. Discriminant function analysis of the otolith
microchemistry data correctly classified 84 - 100% of fish to their respective sites within Bahamas, and 67 - 80%
within Belize. At both Bahamas and Belize, individuals from each site were primarily separated using
concentrations of strontium and lead. Small-scale variability among sites within Bahamas and Belize suggests that it
may possible to classify adult reef fish to their juvenile habitat. This would potentially permit quantification of the
relative importance of mangroves and other habitats in sustaining reef fish populations.
Plant-animal interactions in the seagrass-coral reef landscape: correlative evidence that grazers control
seagrass demography and reproductive potential
Juliet Christian* and John F. Valentine. Dauphin Island Sea Lab and University of South Alabama, 101 Bienville
Blvd., Dauphin Island, AL 36528, USA.
Marine herbivores are widely recognized to exert an extraordinary influence over wholly exposed algal-dominated
plant assemblages. Intense grazing, both on attached algae and marine phytoplankton, has been shown to trigger
dynamic shifts in plant community dominance from larger, palatable and more easily accessible species of algae
towards those communities dominated by less accessible, unpalatable species. In contrast, we know far less about
the impacts of marine herbivores on rooted plants, such as seagrasses, whose meristems are mostly found
belowground and probably seldom damaged by grazing. Using seagrass samples collected from two sites (Little
Grecian and Dry Rocks Reefs) along the northern Florida Keys Reef Tract, and herbivore assays conducted at these
same sites, we provide new evidence that marine herbivores can control both seagrass population biology and
possibly reproduction. Demographic analyses of seagrass shoots, and the results of seagrass grazing assays placed at
the same locations the shoots were collected, suggest that marine herbivores can control both shoot age and
flowering intensity. Specifically, flowering intensity was greatest, and shoot age was younger, where grazing was
intense. These results, although preliminary, provide new support for our hypothesis that the dynamical interaction
between marine herbivores and seagrasses has been greatly underestimated.
Environmental influences (food, current and wave motion) on skeletal regeneration in the burrowing
brittlestar Ophiophragmus filograneus.
Lee Ann J. Clements,* Benjamin Bryant, and Elizabeth Remily. Departments of Biology and Marine Science,
Jacksonville University, Jacksonville, FL 32211, USA.
Experiments were conducted to determine the effects of three environmental variables (food ration, unidirectional
current and wave motion) on skeletal formation during arm regeneration by the brittlestar Ophiophragmus
filograneus. Animals, were collected from the Banana River Lagoon near Melbourne, FL, prepared by
anesthetization and removal of two non-adjacent arms, and placed in experimental tanks (feeding ration: low = 12
mg, medium = 24 mg, high = 36 mg/animal weekly), flumes (high flow = 3 cm/s, low flow = 1.5 cm/sec) or wave
tanks (control = 0 waves/min, wave motion = 72 waves/min, 2.5 cm amplitude, 0.833 m wavelength) with a 3-cm
layer of natural sediment substrate for 4 weeks. At the end of each experiment dry weight, ash weight and ash-free
dry weight were determined for regenerated and non-regenerated portions of each animal. Total regeneration
increased with feeding ration; however, the ratio of skeletal weight to tissue weight did not remain constant.
Animals in the low food ration treatment had approximately 50% of their dry weight as skeleton, while animals in
the medium and high rations had 30% of their dry weight as skeleton. Animals in the low flow conditions
regenerated more tissue, but proportionally less skeleton than those in the high flow condition. Wave motion
resulted in half the tissue regeneration seen in the no-wave treatment. The percent of skeleton did not differ between
the two wave treatments. Low tissue regeneration in the wave and flow treatments may represent reduced feeding
opportunity. The amount of tissue regenerated in these treatments is similar to the amount in the low food ration
experiment. In both flow and wave conditions, the proportion of skeleton regenerated was greater than in the low
food ration. These results suggest that hydrodynamics affect both energy acquisition and the amount of energy
allocated to skeleton during regeneration.
Dominance hierarchies of gray triggerfish, Balistes capriscus, schools
David W. Cleveland* and Kari L. Lavalli. 1Southwest Texas State University, Department of Biology, 601
University Drive, San Marcos, TX 78666, USA.
Preliminary laboratory studies preclude that size may play the most important role in determining one’s dominance
rank in a small school (5 individuals) of gray triggerfish. Observations in large mesocosms (5 m wide x 5 m long x 1
m deep) at the Keys Marine Laboratory, Long Key, FL were conducted in 2001 to determine dominance hierarchy
structure of independent groups of gray triggerfish. Identical studies are to continue at the Florida Marine Fisheries,
Panama City, FL in March and April 2002. This report focuses solely on group interactions of 5 fish. Gray
triggerfish apparently have a size-related rank in a seemingly linear hierarchy. A larger fish usually dominates over a
smaller fish. Dominant fish initially assert their rank with aggression and display. Chasing, biting, and/or ramming
characterize triggerfish aggression. Displays consist of trigger and fin flaring accompanied by a lightly barred olive
coloration. Sub-dominants respond with a different display and body posturing or by fleeing. Sub-dominant fish
display coloration from a solid black to white or varied degrees of individual specific patterns and color
combinations. Body posture usually involves up or down head position with or without fin and trigger-up display.
As of yet, the sex of the fish appears to show no relationship to dominance rank. Dominant fish subdue small prey
items (e.g. urchins) and chase sub-dominants away. Triggerfish appear to show co-operation in attacks on larger,
more dangerous prey items (e.g. spiny lobsters).
Habitat utilization by tidal creek nekton: seasonal and spatial patterns of associated fauna within intertidal
oyster reefs, marsh and mudflats
Loren D. Coen* and Jessica A. Stephen. Marine Resources Research Institute, South Carolina Department of Natural
Resources, Charleston, SC 29412, USA.
Tidal creeks and Spartina marshes dominate the southeastern U.S., representing some of the most productive and
valuable ecosystems there, providing critical feeding, spawning, and nursery areas for finfish, invertebrates, and
when exposed, waterfowl. In this estuarine landscape, numerous species utilize one or more habitats, especially
given their diurnal exposure. Recently work in NC, SC, and VA, recognizes oysters as ‘ecosystems engineers’,
affecting population, community and landscape level processes. In 1994, we initiated a study examining the
development and functioning of intertidal oyster reefs and associated restoration success criteria at several sites.
Here we discuss one aspect, our 1998-2000 nekton sampling of oyster reefs, fringing marsh, and mudflat habitats
(5X) using 24 m2 lift nets in September and May. Nine areas (3 replicates/habitat) were sampled near Charleston at
one of our long-term study sites (see related poster by Stephen et al.). Over 14,000 animals, in 58 taxa were
collected. Callinectes spp., penaeid shrimp, Palaemonetes spp. and finfish showed diverse, but consistent spatial
and temporal patterns. Overall, marsh nekton diversity and abundances exceeded those over bare substrate (48 vs.
38 spp. respectively). However, oyster habitat often matched the marsh in abundance, diversity (overall 34 spp.),
and biomass. Interesting faunal patterns emerged, with Palaemonetes vulgaris consistently associated with oysters,
and P. pugio with fringing marsh. Bay anchovies were primarily collected over oysters or mudflats; mojarra and
spot over mudflats; silver perch, juvenile grey snapper, and mummichogs over marsh. Post-larval and juvenile
shrimp (penaeids/carideans) were most abundant in marsh, adults over oysters or mudflats. As we suggested above,
our studies support the notion that oyster reefs approach marsh grass in importance as critical habitats, especially
when one sums across all of their attendant ecosystem services (e.g., filtering, marsh shoreline stabilization, flow
impacts, habitat). Likewise, intertidal mudflats should also not be dismissed.
Mussel patch dynamics and spatial temporal heterogeneity
R. A. Coleman,1,2* L. Benedetti-Cecchi,3 J. Paula,4 N. J. Frost,1 and S. J. Hawkins.1,5 1School of Biological
Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK; 2School of Biological
Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK; 3Dipartimento di Scienze dell'Uomo e
dell'Ambiente,Via A. Volta 6, I-56126 Pisa, Italy; 4Departamento de Zoologigia e Antropologia, Faculdade de
Ciências, Universidade de Lisboa, Campo Grande, Lisboa – P-1700, Portugal; 5The Marine Biological Association
of the UK, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK.
On exposed shores in Western Europe, mussels and limpets coexist in a mosaic; similar patterns have been observed
in South Africa and North America. On N.E. Atlantic shores, limpets are important grazers which control algae on
mussel dominated shores, shown by the proliferation of algae when limpets were killed following the Torrey
Canyon oil spill. Mussels have more physical effects, acting as ‘ecosystem engineers’ by increasing substrate
complexity and also species richness. Physical disturbance is significant in disrupting mussel mosaics, since as
mussels grow, they move away from the substrate, and form hummocks. This makes them more susceptible to wave
removal, leaving bare patches that are susceptible to pre-emption by limpets, thus preventing recolonisation of
space. Whilst much data exists on mussel dynamics generally limpet populations and grazing, there are few studies
available of spatial and temporal dynamics of mussel patches in mosaics on rocky shores. This work quantified the
scale of spatial heterogeneity in mussel patches on exposed rocky shores and measured spatial and temporal
heterogeneity in mussel patches at a variety of spatial scales.
Ecosystem engineers alter benthic processes: power law transport of sediment, larvae, and postlarvae in a
spatially complex soft-bottom mussel bed
John A. Commito,* Emily A. Celano, Holly J. Celico, and Craig P. Johnson. Environmental Studies Department,
Gettysburg College, Gettysburg, PA 17325, USA.
At each of four sites in Guard Point Cove, Maine, USA, we used cores, bedload traps, and plastic mesh squares in
bare sediment and mussel bed habitats to determine ambient densities and rates of sediment flux, several measures
of postlarval dispersal, and mussel larvae settlement. There were few significant Site effects and no Habitat x Site
interactions but numerous Habitat effects. Compared to the bare sediment, the mussel bed had: fewer species;
higher density of oligochaetes (the dominant species at Guard Point); lower densities of non-oligochaetes; and
higher sediment flux and non-oligochaete per capita dispersal rates. Dispersal rate was negatively correlated with
ambient density and positively correlated with sediment flux, indicating both density-dependent and passive
components in transport processes. Sediment flux, postlarval dispersal, and larval settlement were characterized by
significant power law distributions, indicating that transport processes were scale-free over the spatial and temporal
ranges of this study. Sediment and animals may be responding to water flow patterns created by complex shoreline
and bottom topography or self-organizing as critical erosion velocities are reached. In contrast, the spatial pattern of
ambient abundance did not follow a power law distribution, suggesting that some ecologically important posttransport processes influencing community structure are not scale-free. This difference between transport processes
and the ambient spatial pattern requires further examination as we attempt to generalize about issues of scale in
ecological systems.
Antioxidant response of Leiostomus xanthurus (spot) to hypoxia
Rebecca Cooper,1* Lisa Clough,2 Mary Farwell,2 and Terry West.2 1Coastal Resource Management Program and
2
Department of Biology, East Carolina University, Greenville, NC 27858, USA; e-mail ruc0826@mail.ecu.edu.
Estuarine organisms along the Southeastern United States often experience hypoxic conditions. In response to
hypoxia, we expect to see a suite of behavioral and physiological changes including an induction of the antioxidant
defense system. We explored the response of the antioxidant defense system in Leiostomus xanthurus (spot). When
challenged by hypoxia (10-25% saturation), spot exhibited an increase in superoxide dismutase activity, an
antioxidant enzyme, in both gill and muscle tissue. While significant increases in activity were observed, interindividual variation accounted for more than 43% of the total variation observed between oxygen treatments. A
review of the literature shows that inter-individual variation in antioxidant enzyme activity is common in fish. The
biological significance of inter-individual variation has not been explored to date. We propose the variation reflects
prior exposure history, with those previously exposed to sub-lethal hypoxia expressing higher antioxidant activities.
This phenomena is known as hypoxic "pre-conditioning" and has recently been proven to increase antioxidant
activity in rats and sharks. We tested the impact of hypoxic pre-conditioning on spot by subjecting individuals to a
series of short, sub-lethal dosages of hypoxia followed by a subsequent challenge to prolonged hypoxia.
Preliminary results show that activity of malondialdehyde, an indicator of oxidative tissue damage, is decreased in
pre-conditioned fish relative to those not pre-conditioned. We predict pre-conditioning will not only increase the
activity of superoxide dismutase, but also decrease the amount of inter-individual variability in spot.
Hydrodynamic characterization of shoal communities in Florida Bay: implications for nutrient uptake
Chris D. Cornelisen* and Florence I. M. Thomas. Department of Biology, University of South Florida, 4202 E.
Fowler Avenue, Tampa, FL 33620, USA.
Florida Bay is exposed to nutrients from anthropogenic sources. These nutrient laden waters traverse the bay and
pass over shallow shoal communities before reaching the Florida Keys reef tract. Methods for estimating the
amount of nutrients these communities can remove from the water column are essential to developing models that
describe large scale nutrient dynamics in Florida Bay. In this research, we present a technique for predicting uptake
rate constants for benthic communities in situ and estimating the uptake efficiency of the shoal communities. The
shoals are characterized by a complex biological community comprised of seagrasses, corals, sponges, macroalgae
and other associated organisms that are exposed to rapid tidal flows. Rates of nutrient uptake by benthic
communities can be strongly mediated by water velocity, which controls characteristics of the diffusive boundary
layer adjacent to uptake surfaces. In this study, the effects of hydrodynamic parameters on rates of ammonium
uptake by the shoal communities are determined in portable field flumes. Uptake rate constants and hydrodynamic
measurements are combined to calculate a measured uptake efficiency for the benthos. Efficiency is estimated for
each experiment as the Stanton number (the ratio of the mass transfer coefficient (S) and the advection of the
nutrient over the benthos). We also demonstrate how Stanton numbers can be predicted from hydrodynamic data
using empirically derived engineering equations. These predicted Stanton numbers are verified by comparison to
those calculated from flume experiments. Predicted Stanton numbers provide a means to estimate the amount of
nutrient removed by the benthos over a tidal cycle based solely on hydrodynamic data and nutrient concentration.
Factors determining host selection of the symbiotic copepod Clausidium dissimile Wilson, 1921 (Crustacea:
Cyclopoidia: Clausiidae) in sympatric populations of Sergio trilobata (Biffar 1970) and Lepidophthalmus
louisianensis (Schmitt 1935) (Crustacea: Decapoda: Callianassidae)
J. L. Corsetti* and K. M. Strasser. Department of Biology, The University of Tampa, 401 W Kennedy Blvd., Tampa,
FL 33606, USA.
The ghost shrimp, Lepidophthalmus louisianensis and Sergio trilobata are two common burrowing decapod
crustaceans in Tampa Bay, FL, which play a crucial role in the environment they inhabit. Ghost shrimp not only
affect the benthic community through bioturbation; the burrow itself plays a crucial role in the benthic community
structure in that it may house several symbionts, one of which is a copepod, Clausidium dissimile. This study was
conducted to investigate factors that may affect the density of C. dissimile on ghost shrimp specimens both in the
field and in the laboratory. Collections of L. louisianensis and S. trilobata were made over a 15 month period to
determine the prevalence of C. dissimile in the field. Analysis of monthly field data showed that species (p =
0.0001), and sampling date (p = 0.0310) all had significant effects on the density of C. dissimile found on a
particular host, with more copepods preferring specimens of S. trilobata over L. louisianensis. Although sex was
not found to have a significant effect on copepod density, percent prevalence of copepods was significantly higher
for females than males in S. trilobata (p < 0.0001). A series of experiments were conducted in the laboratory to
determine if preferences mirrored the observed trends from the field data. The laboratory experiments supported
observations from the field in that C. dissimile significantly preferred S. trilobata over L. louisianensis (p < 0.001).
However, unlike the field data, specimens did not appear to prefer females over males when size was held constant.
Higher colonization of females than males in the field may instead be attributed to differences in size and behavior
between the sexes.
Water quality and coral health at Porto Seguro reefs, southern Bahia, Brazil
Ozeas S. Costa Jr.,1* Martin J. Attrill,1 and Malcolm Nimmo.2 1Benthic Ecology Research Group, Department of
Biological Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, U.K.; telephone +44 1752
232951; fax +44 1752 232970; e-mail ocosta@plymouth.ac.uk.; 2Department of Environmental Sciences, University
of Plymouth.
Human activities have substantially increased the natural flux of nutrients to coastal systems worldwide. In the
particular case of coral reefs, the research carried out so far has sought to evaluate the extent of the phenomenon and
find means and measures to mitigate its consequences. In Brazilian reefs, all major stresses (sedimentation,
overfishing, tourism-related activities and nutrification) are human induced.
To assess water quality levels in Porto Seguro Bay, a highly visited tourist area, a series of physico-chemical
parameters were measured on three distinct coral reef sites: 1 offshore and 2 nearshore reefs. Benthic surveys were
also performed in all sites to investigate relationships between water quality and benthic community composition.
Sampling was undertaken in rainy and dry seasons.
All measured parameters have demonstrated a clear inshore-offshore gradient, with the offshore reef presenting four
times less chlorophyll concentrations and three times less suspended solids than nearshore reefs. Higher
temperatures nearshore (decreasing during rainy season) are likely to be related with terrestrial contribution
(groundwater discharge and surface run-off). An inverse salinity pattern (higher offshore) also indicates
considerable dilution nearshore, especially during the rainy season. Nutrient concentrations also decrease with
increasing distance from the shore, providing further evidence of significant terrestrial sources of nutrients, both
natural (rivers, mangroves, grass-bed detritus) and anthropogenic (wastewater seepage, agricultural run-off). The
inshore-offshore gradient in nutrient concentration was negatively correlated with coral cover. Such a correlation
suggests that an adverse effect of nutrients may be occurring, especially because this gradient was positively
correlated with percent cover of both macroalgae and zoanthids.
Marine reserves in the Florida Keys National Marine Sanctuary: are they protecting spiny lobsters?
Carrollyn Cox* and John H. Hunt. Florida Fish and Wildlife Conservation Commission, Florida Marine Research
Institute, South Florida Regional Laboratory, 2976 Overseas Highway, Suite 119, Marathon, Florida 33050, USA.
If marine reserves are effective in protecting spiny lobsters, Panuliurs argus, from harvest, we expect that lobsters
will become larger and more abundant inside the reserves than outside. We have monitored spiny lobsters in the
Florida Keys National Marine Sanctuary reserves since their establishment in 1997. We sampled thirteen reserves
and paired reference areas twice a year, during the closed and open fishing seasons. Reserves are comprised of 11
(ca. 82 ha) Sanctuary Preservation Areas (SPAs), one large (515 ha) SuperSPA and one 3,000 ha Ecological Reserve
(ER). Sampling consisted of a 60-minute search during which we enumerated and attempted to catch and measure
all lobsters observed. In 1997, mean lobster size was below the legal limit in both reserves and references. Since
protection, mean lobster size in reserves has been larger than legal size, whereas in references, it remained below the
legal limit. In all years, mean size of legal lobsters was larger in reserves than in references. Additionally,
abundance of very large lobsters has increased in the ER relative to its reference area. Lobster abundance varied
among years with highest abundance in1999 and lowest abundance in 1998. In most years, abundance declined in
both reserves and references during the open season, but the decline was less precipitous in reserves. The decline in
lobster abundance inside reserves during the fishing season indicates that overall, the reserves are too small to totally
protect lobsters from harvest. However, viewed separately, several of the marine reserves, including the ER, appear
to provide at least a temporary refuge for spiny lobsters, while others do not appear to function as lobster reserves at
all. Effectiveness appears to be a function of reserve size, location, and habitat protected relative to spiny lobster
life history.
Soft-bottom benthic assemblages associated to intertidal boulder fields: testing for generality of patterns
across time and space
J. J. Cruz.* Centre for Research on Ecological Impacts of Coastal Cities, Marine Ecology Laboratories A11,
University of Sydney, NSW 2006, Australia.
Boulders offer a challenging opportunity to study different ecological processes because they represent discrete units
of study. They house a series of organisms that are not found in any other intertidal habitat. Boulders provide three
microhabitats: the upper and the lower surface of boulders and the substratum underneath the boulders. There have
been no studies on assemblages in sediments under boulders, despite the habitat there being very different from
sediments without a boulder. This study analysed patterns of distribution of soft-bottom benthic assemblages living
in intertidal boulder fields. Differences between the assemblages living under the boulders and outside the boulders
were predicted. Two coastal (“exposed”) and two estuarine (“sheltered”) locations were sampled during August
2001 and three “exposed” and three “sheltered” during November 2001 in New South Wales, Australia. In each
location and each time, two corer (9 cm diameter x 10 cm deep) of sediment were collected under six boulders (1500
cm2 to 2000 cm2 each) and from six areas, of similar size, in sediments adjacent to (<50 cm from) boulders, using a
suction sampler. Samples were sieved at 0.5 mm, sorted and the organisms identified to the highest possible
taxonomic resolution. Results showed that assemblages living under boulders were different from assemblages
living outside boulders, but only at the “sheltered” locations. These patterns of distribution, however, change
through time and are highly variable among the “sheltered” locations and among boulders. Several models can be
proposed to explain these patterns of distribution. Here, we suggest that differences in the movement and the shape
of the boulders could explain the variability among boulders and among locations. The shape of the boulder could
affect physical variables, such as the flow of the water under the boulder and consequently the dynamic of the
sediments and the availability of nutrients.
A research coordination network to study the historical ecology of the trans-Atlantic marine biota
Cliff Cunningham.* Biology Department, Duke University, Durham, NC 27708, USA.
This proposal seeks to develop the great potential of the temperate North Atlantic Ocean as a system for studying
historical ecology, which is the study of ecological communities from a phylogenetic perspective. The trans-Arctic
exchange of marine organisms in the late Pliocene established many species of Pacific origin in the North Atlantic
Ocean. This natural experiment—along with episodes of trans-Atlantic migration of endemic Atlantic taxa—placed
many of the same species on both coasts of the North Atlantic. These coasts differ dramatically in almost every
way, including glacial activity, productivity levels, predominant substratum type, and biodiversity. By comparing
the ecology and evolutionary history of sister taxa found on both coasts of the North Atlantic, we can uncover the
importance of historical and evolutionary differences which otherwise are obscured by taxon based differences. In
addition, scientists on both sides of the North Atlantic are working to determine anthropogenic effects, such as
human mediated species introductions. Coordination of their efforts would strongly enhance the usefulness of their
results for policy makers.
Our network will bring together marine ecologists, population geneticists and phylogeographers, oceanographers,
paleontologists and paleoclimatologists. These meetings are intended to accomplish five specific objectives:
• Bring together evolutionary biologists (phylogeographers, population geneticists, and systematists) specializing in
marine fish, invertebrates, and algae to coordinate sampling efforts and analysis to synthesize patterns held in
common among these taxa.
• Synthesize existing knowledge about existing diversity on both sides of the Atlantic, exploring productivity and
other factors as explanations for trans-Atlantic differences.
• Encourage collaboration resulting in joint of experiments comparing the ecology of sister taxa on both sides of the
North Atlantic.
• Bring ecologists and evolutionary biologists into contact with the oceanographers and paleontologists whose work
is essential to understanding the histories of the communities and organisms involved.
The impacts of Upogebia pugettensis populations on organic matter and nutrient cycling in Pacific northwest
estuaries.
Anthony F. D’Andrea1 and Theodore H. DeWitt.2* 1NRC Research Associate, U.S. Environmental Protection
Agency, Newport, OR 97365, USA; 2U.S. Environmental Protection Agency, Newport, OR 97365, USA.
The burrowing thalassinid shrimp, Upogebia pugettensis, is a major ecosystem engineering species of Pacific
estuaries and can structure the physical, chemical, and biotic properties of benthic habitats. This study utilized
incubations, benthic chambers and porewater peepers to quantify the role of U. pugettensis on OM remineralization
processes in Yaquina Bay, Oregon. In Upogebia-dominated habitats, the flux of reactive OM into sediments was
~2-4 times greater than areas lacking shrimp. Sediment oxygen uptake was 2-7 times greater in the presence of
shrimp and increased linearly with shrimp burrow density (R 2 = 0.8). Similarly, the dissolved inorganic nitrogen
(NH4 and NO3) flux from the sediments to overlying water increased with burrow density (R2 = 0.66) and was ~2-12
times greater than “no shrimp” habitat. At mid- and high shrimp densities (55 and 130 burrow openings 0.25 m-2,
respectively), nitrate became proportionally more important to DIN efflux from the sediments indicating a potential
density-dependent increase in nitrification and subsequent denitrification in Upogebia burrow walls. Porewater
concentrations of ammonium and phosphate in the top 30 cm of the sediment column were reduced at mid- and high
shrimp densities relative to sediments with few shrimp, presumably due to bioirrigation. In contrast, porewater
profiles in sediments with low shrimp density (20 burrow openings 0.25 m-2) or “no shrimp” suggested solute
advection was dominated by diffusive transport. Shrimp bioturbation results in the rapid burial of OM, leading to a
large inventory of reactive OM in sediments dominated by burrowing shrimp relative to no-shrimp habitats. The
high flux of DIN in shrimp-dominated habitats ensures that products of decomposing OM are recycled back to the
overlying water, rather than accumulating in the sediments as appears to occur in habitats lacking burrowing shrimp.