Evaluation of modified Sphyrion tags for marking Caribbean spiny lobsters, Panulirus argus
Meaghan C. Darcy1,2* and Carrollyn Cox.1 1Florida Fish and Wildlife Conservation Commission, Marathon, FL, USA; 2Marine, Earth, and Atmospheric Sciences Department, North Carolina State University, Raleigh, NC, USA.
Mark-recapture studies have been traditionally employed in ecological and fisheries research to provide quantitative estimates on growth, movement, and mortality. Major assumptions of tagging studies are that the tags are permanent and do not effect the physiology and behavior of the animal. External tags have been used in long-term tagging studies and have been studied extensively, but have produced varying results for a variety of crustaceans. We conducted a laboratory study to investigate the suitability of modified Sphyrion tags by examining tag retention and comparing survival and growth rates of tagged and untagged P. argus. Male and female lobsters from two size classes, adults (76-90 mm CL) and large juveniles (61-75 mm CL), were used in the experiment. The lobsters were checked daily for evidence of mortality and ecdysis, and weekly for tag retention. The results show that 73 percent of all tagged individuals, experienced tag loss at the end of 24 weeks. No effect of sex or size is apparent. A three-percent difference in mortality was observed between tagged and untagged individuals. However tagged females of both size classes experienced higher rates of mortality than their untagged female conspecifics. The difference between mean total growth of tagged and untagged lobsters was 0.86mm, with untagged being larger. Females grew substantially less than males for both tagging treatments and grew less than their untagged female conspecifics. This study was conducted during mating season for lobsters, which may have affected mortality and growth of female lobsters. The data indicates that the modified Sphyrion tag may not be suitable for long-term tagging studies or studies being conducted during reproductive periods for large juvenile and adult lobsters.
The results of monitoring hard corals restored following the installation of telecommunication cables off Hollywood, Florida
Donald R. Deis.* 7785 Baymeadows Way, Suite 202, Jacksonville, FL 32256; telelphone (904) 367-8683; facsimile (904) 733-6621; e-mail .
The installation of five telecommunication cables at a cable station off Hollywood, Florida, caused the dislocation of 160 coral colonies, which were repaired. Monitoring of the repaired coral colonies, as required by the state and local environmental permits, has focused on survivorship. Survivorship has been taken to mean both successfully reattachment to the bottom and the effect of detachment and repair on the overall health of the colony, particularly in light of the decline of overall health of corals worldwide. A factorial experimental design was used to examine the effects of repair on the incidence of disease and mortality in the coral colonies. The experimental design also examined the potential differences between the reef systems, which occurred at different depths, and the five cables. Thirty repaired coral colonies and thirty reference coral colonies were examined at six months (February 2000), one year (August 2000) after repair, and two years (August 2001). ANOVA was used to understand the significance of any differences between the observations.
All of the monitored, repaired corals have been found to be secured to the hard bottom reef surface by the repair process. Slightly more bleaching occurred in the one-year monitoring period; however, bleaching was not prevalent in the monitored corals during either period. No significant difference was found in the incidence of bleaching between the restored and the reference corals and between the second and third reefs. A significant difference was noted in the incidence of bleaching between the cables. Documented sources of recent mortality included serpulid (tube) worms, algae, and sponges. No significant difference in the percentage of recent damage was found between the restored and reference corals, between the second and third reefs, or between the five cables during this monitoring period. Year two results are being analyzed.
Food-web structure in introduced and native mangrove communities; a Hawaii-Puerto Rico comparison
A. W. J. Demopoulos,* L. A. Crawford, and C. R. Smith. Department of Oceanography, University of Hawaii, Honolulu, Hawaii, USA.
Seven species of mangroves were introduced to the Hawaiian Islands from Florida in 1902 to reduce coastal erosion. At present, large portions of low-energy coastlines and stream banks are fringed by the red mangrove, Rhizophora mangle. This species has high dispersal capabilities, broad tolerance, and few natural enemies in Hawaii; as a consequence, the mangrove habitat appears to be expanding rapidly. Prior to the very recent invasion of mangroves, the intertidal zone of Hawaii essentially lacked vascular plants. The introduction of mangroves to intertidal habitats can dramatically alter a variety of ecologically important characteristics, e.g., rates of water flow, sedimentation, and detrital input. Mangroves produce large amounts of tannin-rich, nitrogen-poor detritus that may require special adaptations to digest. In Hawaii, animals are unlikely to have had time to adapt to this unique food source. Therefore, we hypothesized that mangrove detritus would be underutilized by detritivores in Hawaiian mangroves compared to native Puerto Rican mangrove habitats. We collected material from a variety of primary producers and consumers in Hawaii and Puerto Rico mangrove habitats and used stable carbon and nitrogen isotope analyses to evaluate potential carbon sources and trophic levels. Our results indicated that detrivores living within Hawaiian mangroves do not substantially utilize mangrove-derived material as a food source. Instead, a majority of the animals appeared to be a part of a particulate organic matter and benthic-green-algae based food web that included approximately 2 to 3 trophic levels. In contrast, several species from native Puerto Rican mangroves exhibited carbon isotopic values that overlapped with mangrove leaf material, indicating that mangrove detritus supports a small, but distinct detritivore community. Thus, in contrast to native mangrove habitats, Hawaiian mangroves do not appear to be supporting a productive, detritus-based community.
Linking habitat change and nutrient dynamics: comparison of food webs and nitrogen fluxes in burrowing shrimp- and oyster-dominated habitats
Theodore H. DeWitt* and Peter M. Eldridge. U.S. Environmental Protection Agency, Newport, OR 97365, USA.
Endemic thalassinid burrowing shrimps are simultaneously dominant ecosystem engineering species and economic pests within Pacific estuaries. Dense populations of two shrimps (Neotrypaea californiensis and Upogebia pugettensis) commonly occupy >75% of intertidal and shallow subtidal tideflats. As a result of their burrowing, feeding, and burrow-irrigation, the shrimps modify the physical, chemical, and biotic structure of benthic habitats and aspects of overlying waters. These activities bring burrowing shrimp into conflict with oyster culture (Crassostrea gigas) because sediment excavated by the shrimps buries or smothers the oysters, and U. pugettensis may compete with C. gigas for food. Pesticide used to control burrowing shrimp on commercial oyster beds in Washington state creates a patchwork of shrimp-dominated and oyster-dominated habitats. Many impacts of pesticide and oyster culture on estuarine fauna have been characterized, but impacts to ecosystem functions have not been investigated. We used inverse-analysis-based food web models to examine how Upogebia- or oyster-dominated tideflats affect the flux of nitrogen between the tideflat and overlying water column. The food web models were parameterized using new and existing data on community structure, physiology, and feeding ecology of species found on un-farmed tideflats dominated by U. pugettensis and on commercial oyster beds. Separate food web models were constructed for four scenarios: Upogebia-dominated tideflats, and oyster beds sprayed with pesticide 1, 12, and 36-48 months before sampling. Two predictions generated by these models are that 1) Upogebia-dominated tideflats may have greater fluxes of nitrogen between the benthos and water column than oyster-dominated tideflats, and 2) Upogebia-dominated tideflats may sustain greater rates of in-situ primary production than oyster-dominated tideflats because of greater nutrient recycling.
Impact of iceberg scouring on benthic assemblages in the Southeastern Weddell Sea, Antarctica
Jennifer Dijkstra1* and Julian Gutt.2 1Department of Zoology, University of New Hampshire, Spaulding Life Sciences, 46 College Road, Durham, NH 03824, USA; 2Alfred-Wegener Institute for Polar and Marine Research, Columbusstrasse, Postfach 120161, D-27515 Bremerhaven, Germany.
Icebergs in the Southeastern Weddell Sea scour the sea floor resulting in deep gouges and/or slumping in the sediment. Until recently, the impact of iceberg scouring on benthic communities was difficult if not impossible to determine due to the lack of a eulittoral zone which prohibited diving. With the advent of the remotely operated vehicle, studies examining the effect of iceberg scouring in this area became feasible. These recent studies demonstrated that scouring of the sea floor resulted in complete destruction of benthic assemblages and created vacant areas that are re-colonized by mobile and sessile pioneer species. The aim of this study was to quantify and compare distinct stages of iceberg scoured assemblages. This was done to determine differences in compositional and structural components of succession. Images taken from a remotely operated vehicle were used to quantify succession in ice scoured regions. Approximately 1500 m2 of videotaped bands from three separate sites were analyzed for structural and compositional components of successional stages. The results of this study showed that total number of individuals, species richness and evenness increased from freshly scoured areas to undisturbed assemblages. Sessile suspension feeders such as hexactinellid sponges and colonial ascidians occupied the majority of space in undisturbed areas, whereas gorgonians dominated newly re-colonized areas. Also, the result of a multi-dimensional scaling plot revealed a subtle gradation in community composition between different stages in re-colonization in which differences between sites at the same successional stage are attributed to the proximity of the stations to the ice-shelf.
Community structure in mussel beds at Logatchev, a deep-sea hydrothermal vent on the Mid-Atlantic Ridge
M. B. Doerries* and C. L. Van Dover. Department of Biology, College of William and Mary, Williamsburg, VA 23187, USA; e-mail .
Chemosynthetic deep-sea communities of the Mid-Atlantic Ridge have been described as having two biogeographic provinces based on preliminary species lists and the distribution of two vent mussel species: Bathymodiolus azoricus in the north (Menez Gwen, Lucky Strike, Rainbow) and B. puteoserpentis in the south (Snake Pit, Logatchev). As a part of a quantitative study of species composition and community structure at comparable habitats across these sites, replicate samples of mussel-bed fauna were collected at Logatchev, the southern-most known site on the Mid-Atlantic Ridge. Preliminary visual observations indicate Logatchev has a high biomass, dominated by ophuroids, compared to other vent sites on the Mid-Atlantic Ridge. Further analysis of samples will estimate species richness, evenness and composition, aiding our ability to define biogeographic provinces on the Mid-Atlantic Ridge. Through quantitative and comparative methods of sampling and examining habitats common to most vents, the information collected from Logatchev and other sites will contribute to our understanding of the underlying processes that lead to the development of chemosynthetic biogeographic zones, their ecological and geographical constraints, and the processes leading to divergent community structures.
The interaction of spatial variation and post-settlement density dependence in the intertidal porcelain crab, Petrolisthes cinctipes
Megan J. Donahue.* Section of Evolution & Ecology, University of California, Davis.
In marine populations, variation in larval supply and post-settlement density dependence interact to determine benthic population size and spatial distribution. Petrolisthes cinctipes is a widely-distributed, intertidal porcelain crab with planktotrophic larvae. Like many marine organisms with planktonic larvae, P. cinctipes exhibits high spatial variation in larval supply and local adult density. In this study, I demonstrate two sources of post-settlement density dependence in Petrolisthes cinctipes: gregarious settlement and intraspecific competition. Using density manipulation experiments in the field, I quantify the positive influence of local adult density on settlement rate. Using field and laboratory experiments, I demonstrate the negative effect of density on individual growth rate in all but the largest size class of P. cinctipes. Finally, I offer a framework for understanding how spatial variation in larval supply and local density will interact with these sources of density dependence.
Sponge dynamics in nearshore hard-bottom communities of the Florida Keys
Scott Donahue* and Mark J. Butler IV. Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529, USA.
Sponges, octocorals, and stony corals are the dominant sessile fauna within hard-bottom communities in Florida Bay, FL (USA). The sponge component of these communities has been cyclically decimated from as early as 1844, but most recently experienced a mass die-off of nearly all sponge species in south-central Florida Bay in 1991 and 1992, apparently in association with phytoplankton blooms. Our sponge transplant studies over the past two years suggest that conditions in these formerly impacted areas have recovered sufficiently to permit the survival and growth of several sponge species. However, continued episodic blooms and the proposed restoration of the Everglades hydroperiod have the potential to impact the sponge community in these areas in the future. Therefore, we are investigating the potential role of several sponge taxa in the maintenance of hard-bottom habitat via their influence on local hydrodynamics and the recruitment of sponges and other sessile fauna. Our preliminary evidence suggests that large physical structures such as sponges enhance scouring of the bottom adjacent to them, with potential impacts on local sediment depth and larval settlement. Thus, we are currently examining the recruitment of sessile invertebrates on artificial substrates placed at varying distances around different sponge taxa.
Possible sources for symbiont variation within the genus Aiptasia over time and space
Meredith Dorner,* Scott Santos, Gemma May, and Mary Alice Coffroth. Buffalo Undersea Reef Research, Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260, USA; telephone (716) 645-2718.
Sea anemones within the genus Aiptasia are distributed worldwide and typically harbor symbiotic dinoflagellates. Aiptasia collected from Japan (A. pulchella), Hawaii (A. pulchella), Eilat (A. pulchella), Bermuda (A. pallida), and Puerto Rico (A. pallida) all harbored zooxanthellae belonging to Symbiodinium clade B, as determined by restriction fragment length polymorphism of nuclear small subunit (n18S)-rDNA. In contrast, A. pallida from the Florida Keys usually host Symbiodinium belonging to clade A. Sampling in Florida in the winter has revealed some individuals which possess Symbiodinium from clades A and B. Two hypotheses are proposed to explain these observations: (1) The Aiptasia sp. found in the Florida Keys are a different species than those found in other areas sampled. (2) The cladal variation observed among the Florida Keys Aiptasi sp. is in response to environmental variation. An ongoing study is evaluating the influence of the environment on this symbiosis by sampling Aiptasia sp. from the Florida Keys each month as well as conducting experiments to determine the effects of light and temperature on zooxanthella clade.
Hitchhiking hydroids: assessing the relationship between the coquina clams Donax and the hydroid Lovenella gracilis
Joanne R. Dougherty* and Michael P. Russell. Department of Biology, Villanova University, Villanova, PA 19085, USA.
The coquina clams in the genus Donax are dominant members of the infaunal community of high-energy sandy beaches. Donax are often found in association with an epibiotic hydroid, Lovenella gracilis. This tufted brown hydroid uses the external posterior end of living clams as a substrate. The significance of the relationship between the clam and the hydroid has not been studied extensively, however some workers suggest that the L. gracilis forms a symbiotic relationship with the clam. I plan to investigate the effect of L. gracilis on the population biology, life history, and distribution of Donax by quantifying the effect of the hydroid on clam growth and rates of predation by gastropods. I will also document the seasonal variation in the association of the hydroid with Donax over the next year. Preliminary field data suggest that there is a size-specific relationship between the clam and the hydroid in that larger clams are more likely to have hydroids, however, the hydroid has been observed on recently settled juveniles as small as 2 mm in length.
Dispersal and recruitment in terrestrial versus marine environments: the benthos is not just an underwater landscape
C. Ashton Drew* and David B. Eggleston. North Carolina State University, Marine Earth & Atmospheric Sciences, Jordan Hall Box 8208, Raleigh, NC 27695, USA.
Existing landscape ecology theory has primarily been developed within terrestrial systems and has not been adequately tested in marine environments. The assumptions and methods appropriate for modeling terrestrial systems might not apply in marine environments. While terrestrial organisms generally move through a landscape, most marine organisms can utilize hydrodynamic currents to disperse over a landscape, requiring a three-dimensional conceptualization of movement patterns. We use a cellular automata model to compare recruitment success resulting from various terrestrial versus marine dispersal strategies within patchy environments. We likewise evaluate how recruitment success of a given dispersal strategy responds to landscape changes. The modeled dispersal strategies are: (1) terrestrial, where an individual may move in any direction based upon habitat preference; (2) passive marine, where an individual cannot move against or perpendicular to the current; and (3) active marine, where an individual can move in any direction but the current significantly biases potential movement. A highly successful recruitment event has a high number of settlers in suitable habitat (maximum survival) and results in a broad spatial extent of recruit distribution across the landscape (spreading risks associated with random environmental perturbations). We conclude: (1) differences in individual dispersal strategy can lead to significant differences in recruitment success within similar landscapes, and (2) the dispersal patterns and overall recruitment success of each strategy responds predictably to changes in landscape structure. We conclude with a presentation of how these modeled results can be combined with remotely sensed landscape mosaics to predict recruitment success marine species with varying dispersal capabilities, including: Nassau grouper (Epinephelus striatus), Caribbean spiny lobster (Panularis argus), Queen conch (Strombus gigas).