GPMB 2008 Colloquium:
Abstracts of Oral Presentations
EFFECTS OF TEMPERATURE ON DIMETHYLSULFONIOPROPIONATE (DMSP) IN SYMBIODINIUM SP.
Miller, J. (GPMB, College of Charleston) and DiTullio, J. (College of Charleston)
Coral reefs are ecologically and economically important in many locations throughout the tropics. However, corals are sensitive to various environmental stressors such as increases in sea surface temperature. Heat stress can cause them to lose their dinoflagellate symbionts in an event known as coral bleaching. Bleaching events have become more common and are an ever growing concern due to global climate change. Dimethylsulfoniopropionate (DMSP) and related biogenic sulfur compounds are believed to be involved in alleviating cellular oxidative stress and on a larger scale can function as part of a negative feedback loop on global warming. Previous studies have shown that DMSP is produced in taxonomically diverse classes of marine phytoplankton as well as coral zooxanthellae. It has been hypothesized that the breakdown of DMSP into the volatile compound DMS can combat intracellular oxidative stress by scavenging free radicals. The majority of research on DMSP has focused on pelagic phytoplankton; however, more recently there has been an increase in the study of DMSP production in coral reefs. This study sets out to further investigate the potential role of DMSP as an antioxidant in the coral symbiotic algae, Symbiodinium. Algal cultures grown at 28°C will be subjected to a higher temperature (33°C) to determine the effects of heat stress on the DMSP production of Symbiodinium. Western blots and glutathione assays will be used as oxidative stress indicators to determine the correlation of DMSP with heat stress.
ROLE OF PARENTAL CONTROL IN THE SYMBIOTIC RELATIONSHIP BETWEEN MOLLUSCAN EGG MASSES AND PHOTOSYNTHETIC ALGAE
Kacenas, S. (GPMB, College of Charleston) and Podolsky, R. (GMBL, College of Charleston)
Intertidal species often possess adaptations that serve to dampen the effects of stresses inherent to existence in the intertidal environment. Encapsulation, one method by which intertidal organisms buffer their developing embryos from environmental stress, can result in hypoxia-induced delayed embryo development at the center of an egg mass. Symbiosis between egg mass and photosynthetic algae is a well-documented solution to this oxygen limitation dilemma, however little research has been conducted to investigate the effects of habitat and parental influence over the extent of this relationship. This research aims to investigate 1) if differences in photosymbiont density between populations of Melanochlamys diomedea Bergh egg masses exist, and 2) if compositional differences between egg masses may explain photosymbiont density differences. Masses were collected from three different locations on San Juan Island, WA (SJI) and processed for chl-a. Data indicate that photosymbiont density is dependant upon collection location, the date the mass was collected (seasonality), and the age of the egg mass. In addition, adult M. diomedea were collected from three locations on SJI and permitted to lay egg masses in the lab; the masses were then transplanted back into the three initial collection locations, recollected after four days and processed for chl-a. Data collected from this transplantation experiment indicate that the location from which an egg mass was initially collected influences the density of photosymbionts regardless of the transplant location. These results suggest possible physiological control in response to environmental influence by M. diomedea adults over the biochemical composition of egg masses.
PROJECT PROPOSAL AND PRELIMINARY RESULTS OF SPATIAL AND TEMPORAL TRENDS OF PERFLUORINATED CONTAMINANTS IN LOGGERHEAD SEA TURTLES ALONG THE EAST COAST OF THE UNITED STATES
O’Connell, S. (GPMB, College of Charleston), Kimmel, T. (MD-DNR), Arendt, M. (SC-DNR), Avens, L. (NOAA), McNeill, J. B. (NOAA), Segars, A. (SC-DNR), and Keller, J. (NIST, College of Charleston)
Fluorinated organic compounds persist in the environment long after they have been used commercially, and perfluorinated compounds (PFCs) are found in a range of goods such as stain-repellents on cookware, leather, clothing, paper, and carpet. PFCs bioaccumulate in blood plasma and liver, and have been found to cause toxicity to the liver and suppression of the immune system. Due to increasing concern, PFCs have been examined in a range of wildlife, including birds, fish, invertebrates, and marine and terrestrial mammals. However, little has been done to measure these compounds in reptiles, and only within the last few years have scientists examined how these contaminants move through the environment by using food web, temporal, or spatial studies. This presentation will present a proposed project that examines geographic and temporal concentrations of PFCs in juvenile loggerhead plasma and will provide available preliminary results. Samples of the geographic study were collected from turtles captured in 2005 and 2006 from Cape Canaveral, FL, Charleston Harbor, SC, Core Sound, NC, and Chesapeake Bay, MD. The temporal study will include PFC concentrations measured from turtles captured in Charleston Harbor, SC, from 2001-2007. Samples will be extracted for 13 PFCs by a solid-phase extraction and quantified using liquid chromatography tandem mass spectroscopy. By broadening the knowledge of how these perfluorinated compounds behave in the environment, this study will help assess the environmental risks posed to loggerhead sea turtle populations by these contaminants along the East coast of the United States.
PRELIMINARY ASSESMENT OF STOCKING STRATEGIES OF STRIPED BASS, MORONE SAXATILIS, IN THE ASHLEY RIVER AND POPULATION STRUCTURE AMONG TWO SOUTH CAROLINA RIVERS
Fountain, J. (GPMB, College of Charleston) and Denson, M. (South Carolina Department of Natural Resources)
Striped bass, Morone saxatilis, a commercially important fish species in South Carolina, have been stocked in the Ashley River to assess stocking strategies. Molecular markers will be used to determine the best stocking size at release. Twelve microsatellite markers have been multiplexed into three groups of four loci for striped bass. In addition, these loci have been used to determine the population structure and estimate the number of migrants per population per generation (Nm) of striped bass in the Savannah River and the Santee River system. This information will be of importance to fisheries managers who must decide how to manage populations of striped bass.
LIFE HISTORY AND POPULATION STRUCTURE OF BERYX DECADACTYLUS (BERYCIDAE) IN THE WESTERN NORTH ATLANTIC OCEAN
Friess, C. (GPMB, College of Charleston) and Sedberry, G. R. (Gray’s Reef National Marine Sanctuary)
Red bream, Beryx decadactylus, is a deep-sea fish found on the continental slopes and around seamounts of the world’s subtropical to temperate oceans. It is targeted by commercial deep-sea fisheries around the globe, and catch rates have declined in most parts of the world. No directed fishery exists yet for red bream in the United States, but it is taken incidentally in the wreckfish fishery on the Charleston Bump, off the southeastern United States. Biological information for red bream is sparse and comes mainly from comparative studies with its sister species, B. splendens. Life history parameters for the Charleston Bump population need to be determined before these fish become a target for the commercial fishery. It is also unknown whether red bream from the western North Atlantic form one genetic stock with the heavily fished eastern North Atlantic population. The proposed research will investigate the age and growth of red bream by otolith analysis, examine its reproductive cycle through gonad histology, and determine population structure in the North Atlantic through mitochondrial DNA analysis. Otoliths, gonads, and genetic samples of red bream from the western Atlantic have been collected by the South Carolina Department of Natural Resources since 2003, and genetic samples from the eastern Atlantic were provided by the University of the Azores. The data from this study will be used to determine spawning season, sex ratios, growth rates and size and age at maturity, thereby providing critical information for the effective management of the South Carolina red bream population.
IDENTIFICATION OF ENZYMES RESPONSIBLE FOR METHIONINE PRODUCTION AND SUBSEQUENT DIMETHYLSULFONIOPROPIONATE (DMSP) BIOSYNTHESIS IN A CLADE F1 SYMBIODINIUM SP. ISOLATED FROM SCLERACTINIAN CORAL (MONTIPORA VERRUCOSE)
McLenon, A. (GPMB, College of Charleston), DiTullio, J. (College of Charleston), and Janech, M. (MUSC)
Dimethylsufoniopropionate (DMSP) is a compound with several proposed functions in the plants, algae and dinoflagellates that produce it (Stefels, 2000). Regardless of its exact function in the organisms responsible for its production, it is an important climatic precursor compound, as DMSP is converted into dimethyl sulfide (DMS) via bacterial and algal degradation, which accounts for over half of the biogenic movement of sulfur to the atmosphere (Ditullio, G.R. et al. 1998). Production by certain species of dinoflagellates could be high enough to be of regional interest climatically (Hill, et al. 2000), but the biosynthetic pathway responsible for DMSP production has yet to be elucidated in Symbiodinium spp. Real time PCR and Western blotting will be used to assess changes in mRNA or protein abundance for the enzymes methionine synthase and S-adenosylhomocysteinase (SAH), which are involved in the production of precursor amino acids leading to DMSP synthesis. It is predicted that a change in DMSP production resulting from a change in environmental conditions will coincide with an increase or decrease in the levels of enzymes that catalyze the synthesis of homocysteine and methionine, as well as the free pool of precursor amino acids, homocysteine and methionine. Temperature and pH conditions predicted by climate change models for the next 200 years (+4oC, -0.35 pH units) will be used to stimulate changes in DMSP production. Concurrent changes in enzyme levels will be used to elucidate the pathway and conditions of increased production.
DISCOVERY OF PLASMA PROTEIN BIOMARKERS AS INDICATORS OF DOMOIC ACID EXPOSURE IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS)
Ferrante, J.A. (GPMB, College of Charleston) and Janech, M. (MUSC)
Mass mortalities of marine mammals are increasingly being linked to exposure to biotoxins, such as domoic acid. Domoic acid (DA) is a neurotoxin produced by the marine diatoms Pseudo-nitzschia sp. After exposure to DA, Z. californianus display symptoms clinically suggestive of neuronal injury, including obtundation, head weaving, seizures, and coma. The purpose of this study is to determine if there are proteins in Z. californianus plasma that can be used as biological indicators, or “biomarkers”, of DA exposure. We hypothesize that changes in the plasma protein profile can be utilized as a discovery tool for biomarker selection in animals exposed to DA. These protein profiles are made visible by using gel proteomic techniques. About 97% of the total protein content of (human) plasma is made up of only twenty high abundance proteins such as albumin and immunogloblulins. Depleting these proteins from the plasma before gel electrophoresis separation allows for the increased visibility of lower abundance proteins on a gel. This phase of the study assessed the effectiveness of the depletion of abundant plasma proteins by columns from three different manufacturers. Plasma samples from healthy sea lions were depleted and separated by 2-dimensional gel electrophoresis (2D-GE). Using PDQuest gel analysis software, each gel spot was matched and compared across gels. The column which provided the best depletion of high abundance proteins, and also allowed for the best visibility of the remaining low abundance proteins, was chosen to be used in the next phase of the study.
THE TRANSCRIPTOMIC RESPONSE OF THE PACIFIC WHITELEG SHRIMP TO INFECTION WITH TAURA SYNDROME VIRUS AND YELLOW HEAD VIRUS Veloso, A. (GPMB, College of Charleston), Warr, G.W. (MUSC), Chapman, R.W. (MUSC), Browdy, C.L. (MUSC), and Gross, P.S. (SCDNR)
The pacific whiteleg shrimp (Litopenaeus vannamei Boone 1931) is the most cultured species of shrimp in the world. The high densities to which the cultured shrimp are exposed, however, increase the odds of disease transmission among the shrimp causing major aquaculture losses and potential contamination of natural environments. Viruses are one of the most common groups among the pathogens that cause high mortalities in L. vannamei. Despite the variety of and devastation caused by shrimp pathogens, it is not well understood how the shrimp handles viral infections. This work uses two of the most pathogenic viruses of the pacific whiteleg shrimp, Taura Syndrome Virus (TSV) and Yellow Head Virus (YHV), together with two lineages of L. vannamei differing on their susceptibility to TSV to better understand what genes are differently expressed by the shrimp under a viral infection. To do so the mRNA from the hepatopancreas of shrimps (24 and 48 hours after infection) will be hybridized to microarray slides containing DNA sequences from 2,469 predicted shrimp genes. Statistical software (BioConductor) will be used to assess differential expression between groups of interest (e.g. resistant shrimp infected with TSV versus susceptible shrimp infected with TSV). The differences in transcriptomic responses will yield a set of candidate genes that could play important roles in shrimp immunity. Thus, in future research it will be possible to test hypotheses about the importance of certain genes in response to disease and resistance to TSV infection.
TOXICITY OF SELECTED CONAZOLE FUNGICIDES TO THE HALOTOLERANT CHLOROPHYTE DUNALIELLA TERTIOLECTA: SUBLETHAL EFFECTS ON OSMOREGULATORY FUNCTION AND LIPID COMPOSITION
Baird, T. (GPMB, College of Charleston) and DeLorenzo, M. (CCEHBR, NOAA)
Conazole fungicides are commonly used to control fungal growth on agricultural crops, golf courses and home lawns. Runoff from applications of these pesticides in coastal areas could adversely impact marine and estuarine phytoplankton populations. The objectives of this study are to determine the toxicity of four conazole fungicides to the marine chlorophyte Dunaliella tertiolecta by examining effects on growth, osmoregulatory function and lipid composition. Using 96 h static algal bioassay protocols, we established EC50 values (i.e., the effective concentration at which population growth rate is reduced by 50%) of 0.34 mg L-1 (95% CI: 0.26-0.41) for propiconazole, 0.60 mg L-1 (95% CI: 0.55-0.65) for hexaconazole, 3.92 mg L-1 (95% CI: 3.67-4.21) for triadimefon and 5.51 mg L-1 (95% CI: 5.31-5.64) for triadimenol. Future work aims to investigate the sublethal effects of conazole exposure on D. tertiolecta’s ability to synthesize and dissimilate its glycerol osmolyte following an osmotic shock. Lastly, additional methods will be developed to generate post-exposure lipid profiles using mass spectrometry to identify any alterations in overall plasma membrane structure. The data generated from this research will benefit pesticide regulators in making informed environmental management decisions.
REPRODUCTIVE DYNAMICS OF COBIA, RACHYCENTRON CANDUM, IN PORT ROYAL SOUND AND ST. HELENA SOUND, SOUTH CAROLINA
Lefebvre, L. (GPMB, College of Charleston) and Denson, M. (SCDNR)
Cobia, Rachycentron canadum, is a prized recreational fish species in South Carolina. Cobia are targeted by hook and line as the fish enter high salinity estuaries of the southern coast of South Carolina on their spring and early summer migration from Florida to the Chesapeake Bay. The annual northward migration coincides with cobia’s spawning season, and as such, the primary objective of the research is to determine if Port Royal Sound and St. Helena Sound, SC serve as spawning habitat. Fish were collected from fishing tournaments, recreational fishermen and guides, and via hook-and-line by SCDNR employees in Port Royal and St. Helena Sounds in April-June 2007. For all specimens, total length, fork length and fish weight were measured. Sagittal otoliths were removed for age determination. Gonads were excised and weighed and a portion preserved for histological analyses. Reproductive status of females was determined through histological analysis of the ovaries. The preliminary data presented will be used in conjunction with plankton sampling and additional adult sampling in 2008 to address the primary objective. While there is no data on the status of the stock and limited information available to determine if cobia are currently over-fished, these findings will provide additional information on cobia reproductive behavior and biology to assist management agencies in making fishery related regulations.
BOTTLENOSE DOLPHIN BEHAVIOR AROUND CHARLESTON, SC
Sturgeon, N. (GPMB, College of Charleston, NOAA) and Owens, D. (GPMB, College of Charleston)
Near Charleston, South Carolina, the most common marine mammal is the bottlenose dolphin (Tursiops truncatus). While local populations have been well studied over the past decade, a behavior schedule does not yet exist. Also, commercial fisheries and marine mammals worldwide are known to frequently interact. The fishery near Charleston with the greatest impact on bottlenose dolphins is the Atlantic blue crab fishery, which has been implicated in a significant number of entanglements. The gear used in this fishery has been known to cause both injury and death to dolphins. In order to produce a behavior schedule and investigate how and why entanglements occur, behavioral focal follows of selected dolphins will be conducted using both continuous and instantaneous sampling techniques. Surveys of local crab fishers will also be conducted in an attempt to determine whether behaviors implicated in other locations, such as pot tipping, are occurring in the Charleston area. In addition data will be gathered regarding dolphin behaviors around blue crab pots and the impact of dolphins on pots and catch. Results of this study will be used to formulate recommendations for managing dolphin interactions with crab pots.
MOLECULAR ECOLOGY OF THE BARNACLE MEGABALANUS COCCOPOMA OVER ITS INTRODUCED RANGE IN THE SOUTHEASTERN US
Williamson, T. (GPMB, College of Charleston) and Zardus, J. (The Citadel)
Invasion ecology is emerging as an increasingly important field as the impacts of human activities on the environment are realized by the world. The effects of dispersal on introduced species globally may be studied through the use of advanced molecular tools. The recent arrival of Megabalanus coccopoma, a Pacific tropical barnacle, to the southeastern coast of the United States provides an opportunity to use these molecular tools to study its establishment and subsequent expansion northward. Analysis of nuclear and mitochondrial DNA by DNA sequencing and gel electrophoresis will be used in characterizing population patterns through phylogenies and western blot assays. Variable tolerance of thermal stress is a possible explanation for potential differentiation among populations. Western-blot immunochemical assays will be used to express heat-shock protein and ubiquitin levels which act as proxies for the amount of stress the barnacles experience. By coupling the molecular data of the metapopulation structure and heat-shock protein expression with thermal oceanographic data, this study will also make conjectures on the likelihood for further range expansion of M. coccopoma along the eastern coast of the United States.
POPULATION DYNAMICS OF ADULT RED DRUM (SCIAENOPS OCELLATUS) IN OFFSHORE WATERS OF SOUTH CAROLINA
Gerhard, J. (GPMB, College of Charleston) and Reichert, M. (SCDNR, MRRI)
Red drum (Sciaenops ocellatus) is one of the most significant recreational fishery species in the southeast U.S., and is exploited along the southern Atlantic and Gulf of Mexico coasts. Since the implementation of slot limits in South Carolina in 1992, only sub-adults have been harvested. Consequently, the vast majority of studies on red drum have occurred on sub-adult stages, resulting in a paucity of information on adults. The Atlantic States Marine Fisheries Commission (ASMFC) and South Atlantic Fishery Management Council (SAFMC) formed a fisheries management plan for red drum in 1984 with the goal of perpetuating the resource and attaining maximum possible economic and social benefits. However, the lack of adult data has made it nearly impossible to assess the health of the stock. Therefore, this study seeks to answer several previously unaddressed questions of adult red drum biology. Random stratified sampling will occur in four locations along the coast of South Carolina using a bottom longline. Every third fish will be sacrificed to determine the following life history and ecological parameters: age structure via otolith processing, sex ratios and maturity via histological processing of gonads, age-at-length, and feeding preferences via stomach content processing. The caught fish that are not sacrificed will be implanted with a PIT tag and released for use in movement studies. These data will shed light on how management restrictions have affected the population and will assist in making future management decisions.
CONTRIBUTION OF SOME REEF FISH SPECIES ON ARTIFICIAL REEFS TO THE POTENTIAL ANNUAL FECUNDITY OF POPULATIONS IN THE SOUTHEASTERN UNITED STATES
Danson, B. (GPMB, College of Charleston) and Harris, P. (SC-DNR)
Artificial reefs are designed to increase fish habitat and provide increased fishing opportunities to anglers. Although there are large assemblages of fish on artificial reefs, no studies have attempted to estimate their contribution to populations off the southeastern U.S. Four artificial reefs on the southeastern continental shelf of the U.S. (two inner-shelf and two mid-shelf) will be surveyed using diver video surveys, chevron traps and hook-and-line during the spawning seasons of five economically and ecologically important species (black sea bass (Centropristis striata), scamp (Mycteroperca phenax), white grunt (Haemulon plumieri), red porgy (Pagrus pagrus), and vermilion snapper (Rhomboplites aurorubens)). Diver video surveys (nine point counts, 360°) will be conducted on each reef at fixed sites and used to estimate the length of individuals and abundance of each species on each reef. Chevron trap and hook and line sampling will be used to collect specimens of each species from which gonad samples will be taken. Histological analysis of these samples will be used to determine the spawning condition of each species at the time of sampling. The length and abundance estimates of the five species will be used with length-specific fecundity data from previous studies to calculate potential annual fecundity for each species on the artificial reefs. These data will then be used to estimate the extent to which spawning on artificial reefs by these five species increase the potential annual fecundity of populations off the southeastern US.
TEMPORAL CHARACTERIZATION OF THE SURF ZONE MACROFAUNA AT FOLLY BEACH, SOUTH CAROLINA
Wilkie, J. (GPMB, College of Charleston) and Harold, A. (GPMB, College of Charleston)
The fish assemblage within the surf zone is widely variable consisting of a large number of individuals which represent a small number of species. Although a few species in the surf zone in the South Atlantic Bight have been well studied, data are lacking for most species, especially fishes. A study will be conducted on Folly Beach, South Carolina in conjunction with a study of the surf zone in Horry County, South Carolina, which has a history of hypoxic events. The study conducted on Folly Beach will result in evaluation of long term changes to the macrofauna in the surf zone by comparing findings to studies conducted from 1969 to 1971 (Anderson et al., 1977), and 1980 (DeLancey, 1989). A 19.8 m by 1.8 m, 9 mm bag seine will be pulled through the surf zone parallel to the shore for 100 m at two sites 0.5 km apart. Samples will be taken biweekly within one hour of low tide in the morning from June 2007 to August 2008. After the seine is beached, each specimen will be preserved, then measured and weighed. Before each seine haul the following physical measurements will be taken: turbidity, temperature, salinity, percent dissolved oxygen, and concentration of dissolved oxygen. Data collected will be analyzed to compare species richness and abundance between counties as well as between seasons. Abundant species will be used in additional analysis to examine any correlations between abundance or biomass and any of the physical measurements.
COMPARISON OF GENE EXPRESSION BETWEEN HYPOXIA STRESS AND BACTERIAL CHALLENGE IN THE PENAEID SHRIMP LITOPENAEUS VANNAMEI
Rathburn, C. K. (GPMB, College of Charleston), Burnett, K. (College of Charleston, Hollings Marine Laboraotry), and Burnett L. (College of Charleston, Grice Marine Laboratory, Hollings Marine Laboratory)
Crustaceans such as the Penaeid shrimp Litopenaeus vannamei often encounter low levels of dissolved oxygen (hypoxia) in their natural environment. Hypoxia induces behavioral, physiology and metabolic responses in these animals, including increases in whole body lactate as well as changes in gene and protein expression. Data from our lab show that shrimp exposed to bacteria exhibit reduced O2 uptake along with increased whole body lactate that may reflect deep tissue hypoxia. We hypothesize that some of the changes in gene and protein expression normally associated with immune responses to bacteria may arise from internal hypoxia. To test this hypothesis, gill and hepatopancreas will be collected from animals held in hypoxia (6.7 kPa PO2, 24 h) or normoxia (20.7 kPa PO2, 24 h) and, in a separate experiment, animals injected with bacteria (1 × 105 CFU g-1 Vibrio campbellii), or saline. Transcriptional profiles of treatment groups will be assessed using custom made cDNA microarrays. Preliminary data show that lactate dehydrogenase activity in the tail muscle of L. vannamei does not change with exposure to hypoxia versus normoxia (p = 0.61); activity of the enzyme in hepatopancreas is currently being examined. PCR primers are being developed for AMP kinase to study its expression in response to the same treatments. (Supported by NSF IOS-0725245)
KEYNOTE SPEAKER ABSTRACT:
MARINE BIOINVASIONS: HISTORY, SCIENCE, AND POLICY ISSUES
Carlton, James (Williams College - Mystic Seaport Maritime Studies Program, Williams College)
We know surprisingly little about the history of the world’s marine animals and plants over the past 1,000 years, particularly the extent to which modern-day distributions have been altered by human activities over the past millennium. The resolution we have since 1850 suggests that many marine communities were impacted dramatically by human-mediated invasions long before marine biologists appeared on the scene. In turn, the diversity of vectors now in play continues to introduce non-native species around the world. We look at some of these invasions in the context of maritime history, modern-day shipping, ecological impacts, and environmental policy challenges.