Alderson, J.E. (GPMB, College of Charleston) and Owens, D.W. (GPMB, College of Charleston)
In many vertebrates, exposure to stress can trigger increased secretion of the steroid hormone corticosterone. Previous studies indicate exposure to stressors such as handling and captivity, extreme heat, and disease increase levels of circulating plasma corticosterone in sea turtles. This study investigates the effect of stress caused by physical injury on the corticosterone stress response in loggerhead sea turtles. Loggerheads were captured during trawling activities conducted by the SC-DNR since 2000. Observed injuries were separated into four recency categories: healed injuries, partially healed injuries, fresh injuries, and instant response injuries (injured by stingrays during capture). Blood was collected and centrifuged immediately, and plasma was frozen for later corticosterone measurement using radioimmunoassay. Levels of circulating corticosterone at various points in time were not significantly different between injured loggerheads and corresponding control (uninjured) loggerheads, regardless of injury category (p=0.061-0.686). Average initial levels of corticosterone were significantly different between loggerheads with partially healed injuries and healed injuries only (p=0.042); however, the corticosterone response over time differed significantly between loggerheads with partially healed injuries and those with healed injuries (p=0.033), fresh injuries (p=0.022) and instant response injuries (p=0.048). These results suggest that the characteristics of the corticosterone stress response in loggerheads may differ depending on the stage of injury healing. Future studies can further increase our understanding of the effect of injuries on the corticosterone stress response in loggerhead sea turtles.
Feltman, P. (GPMB - College of Charleston, NOAA) and Van Dolah, F. (NOAA, Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC)
The symbiotic relationship between corals and dinoflagellates of the genus Symbiodinium provides the basis for a diverse marine ecosystem in the otherwise oligotrophic tropical waters of the world. Coral bleaching, characterized by the impairment or loss of symbionts, is a phenomenon that can lead to large-scale coral mortality. This project seeks to characterize stress responses in Symbiodinium that may be important precursors to bleaching events. The stress response in another dinoflagellate, Karenia brevis, consists of constitutively expressed stress gene transcripts becoming actively translated to produce stress proteins (Lidie, 2007). Translational control of gene expression in dinoflagellates appears to be mediated by spliced-leader (SL) trans-splicing of mRNAs. An analysis of 15 dinoflagellate species, including Symbiodinium, found the identical SL on diverse mRNAs. This suggests that Symbiodinium may also use post-transcriptional control in its stress response. Furthermore, a phenomenon of “spliced-leader silencing” described in Trypanosoma, may simultaneously suppress translation of non-stress genes by leading to an increase of polycistronic messages unable to enter the translated pool. The goal of this project is to characterize heat-shock response mechanisms in Symbiodinium. Three specific objectives are (1) to define a heat-shock response by stress protein expression, (2) demonstrate if stress gene transcripts are controlled translationally, and (3) determine if the SL transcript decreases in abundance and results in polycistronic messages for non-stress genes. Results to date will be presented that establish the response of a Symbiodinium clade B isolate from Monastrea to 5°C heat shock over an acute timecourse of 0.5, 1, and 4 h.
Fernandes, D.A.O. (GPMB, College of Charleston) and Podolsky, R.D. (College of Charleston)
A striking consequence of rising levels of atmospheric carbon dioxide concentration is the increase in of dissolved CO2 in the world’s oceans. High levels of dissolved carbon dioxide lowers seawater pH and represent a threat to organisms that produce calcified structures, such as corals, molluscs and crustaceans. Early development represents the most vulnerable time in the life history of marine organisms and can be particularly susceptible to small changes in seawater properties. I examined CO2-related changes in shell deposition of the intracapsular stages of the intertidal snail Nassarius obsoletus. Egg capsules were raised in seawater under conditions that simulated three scenarios of atmospheric CO2 concentrations: current CO2 levels, 2x current CO2 levels and 4x current CO2 levels. Newly hatched veligers were used to measure larval shell length and the amount of inorganic content deposited per larvae throughout development. Data are still undergoing analysis and results will be presented. Future directions of this study are to address how changes in calcium carbonate shell formation due to seawater acidification affects larval vulnerability to predation.
Ferrante, J.A. (GPMB, College of Charleston), Arthur, J.M. (MUSC; Ralph H. Johnson Veterans Affairs Medical Center), Gulland, F.M.D. (The Marine Mammal Center), Hill, B. (MUSC), Almeida, J. (MD Anderson Cancer Center, University of Texas) and Janech, M.G. (MUSC; Ralph H Johnson Veterans Affairs Medical Center)
Domoic acid toxicosis (DAT) is a health issue for the California sea lion (CSL). The diagnosis of DAT by detection of domoic acid (DA) in body fluids remains difficult due to the rapid clearance of DA from the body. We investigated whether serum cytokines could be utilized as biomarkers of DA exposure. CSL serum samples were acquired from The Marine Mammal Center and divided into three groups; CSL’s with acute DA (N=25), CSL’s with leptospirosis (Lepto) (N=23), and CSL’s recovering from another ailment not DA or leptospirosis (NDL) (N=25). We attempted to measure 27 cytokines using a human cytokine multiplex bead assay (Bio-Rad). Three of the cytokines showed a significant change between DA and non-DA animals (p<0.05). Receiver operator characteristic (ROC) curves were calculated for each cytokine. Area under the curve (AUC) values did not exceed 0.552 for each of the 27 cytokines. Nearest related neighbor (NRN – a non-parametric support vector machine) and artificial neural network (ANN) models were utilized to classify CSLs into DA or non-DA categories based on all 27 cytokine levels as a group. For the NRN, the AUC for the ROC was 0.886. This model had a high degree of predictability using cytokines IL-7, IL-10, MIP-1α, Basic-FGF, MIP-1β, Il-2, GM-CSF, IL-15, and IL-1b. The AUC of the ANN was 0.878. In conclusion, individual cytokines were not shown to adequately discriminate CSL’s with DAT. The NRN and ANN models used several cytokines and better classified CA sea lions with domoic acid toxicosis.
Hedgespeth, M. (GPMB, College of Charleston), Sapozhnikova, Y. (NOAA/CCEHBR, CHHR) and Wirth, E. (NOAA/CCEHBR, CHHR)
PPCPs include commonly used over-the-counter, prescription, and veterinary drugs, as well as chemicals found in cosmetics and common household products. These chemicals may be introduced into aquatic environments by both non-point and point sources including domestic wastewater treatment plant effluents. Relatively little is known about the effectiveness of such facilities in the United States to remove PPCPs during wastewater treatment and the fate and distribution of PPCPs or their metabolites once released into marine environments. Beginning in March 2009, we examined monthly chemical concentrations of 21 PPCPs in influent and effluent collected from two local wastewater treatment facilities, as well as six surface water samples collected near treated effluent discharges in the Charleston Harbor. The presence of PPCPs in aquatic environments creates possible risks for health impacts on marine organisms; thus, a select number of compounds in this study were used in an acute exposure screen for potential effects on gill tissue respiration of the Eastern oyster (Crassostrea virginica). Preliminary results suggest clear differences in PPCP concentrations among sewage influent and effluent samples. Sixteen compounds were detected in the influent samples, thirteen in effluent samples, and nine in harbor samples. The concentrations of most PPCPs were reduced in effluents in comparison to influents, although this trend was not universal. Sampling and analysis will continue through February of 2010. Upon completion, this study will be critical in understanding the efficacy of wastewater treatment on PPCPs, the local distribution of PPCPs in estuarine waters, and will help to shed light on important environmental questions concerning PPCP distribution in the marine environment.
Johns, C. (GPMB, College of Charleston)
Since the merger of genetics and genomics was proposed in 2001 by Jansen and Nap, expression genetics, as the field is now called, has received an increasing amount of attention. For many years gene expression has been thought to be the driving force of evolution and in order for evolution to occur there must be a genotype-phenotype relationship. Phenotypes can be determined genetically and/or by environmental factors. If expression levels are treated as quantitative phenotypes, then the question becomes what kind of role do genetics and the environment play in determining the phenotype of organisms? This study will attempt to examine the amount of genetic variation and differential expression between the eastern oyster, Crassostrea virginica, from three locations in Mississippi. Nine previously described polymorphic microsatellites with di- and trinucleotide repeats will be used to determine the amount of oyster genetic variation., and a cRNA microarray designed from an Crassostrea virginica EST library at marinegenomics.org will be used to assess differential gene expression between oysters. The presence or lack of a relationship between expression and genetic variation will be examined in an effort to partition environmentally and genetically controlled gene expression. The expression and genetic data will be examined using cluster analyses.
Kreutzer, A. (GPMB, College of Charleston), Hadley, N. (SC DNR) and Shervette, V. (University of South Carolina)
Abandoned crab traps are a problem in many coastal areas; when left in the water and marshes they continue fishing, needlessly killing crabs, turtles, and other animals. The goal of this project was to test the utility of these crab traps as a base for artificial oyster reefs. Oyster shell, the media traditionally used for oyster restoration, is expensive to buy and can be ineffective in muddy areas. To start, treatments of crab traps and standard oyster-shell-based restoration techniques were placed at three intertidal locations around Charleston, South Carolina. After nine months, crab traps that had been coated in cement recruited an average of 2,438 oysters per square meter, the highest recruitment of the crab trap treatments. The oyster-shell-based restoration techniques did, however, recruit significantly more oysters (p value = 0.001) than the cement coated traps with an average of 12,435 oysters per square meter. To evaluate the potential of crab traps for use in soft sediment areas, crab traps filled with recycled oyster shells already laden with live oyster spat were deployed in firm and muddy substrates for nine months. These crab traps showed no significant sediment accretion in even the soft substrate. Furthermore, the oyster spat in crab traps on both the hard and soft substrate attained mean sizes of 25.69mm and 30.89mm respectively, with survival rates of 38.5% and 34.6%. Recycled crab traps show good potential as oyster reef building blocks, particularly if coated with cement, and could allow oyster restoration in many areas which are not amenable to existing restoration techniques using oyster shell alone.
McLenon, A.L. (GPMB, College of Charleston) and DiTullio, J. (College of Charleston)
It is apparent the effects of climate change variables such as increasing sea surface temperature and CO2 levels on algal communities are complex. In addition, the interactive effects of these variables have not been adequately addressed. For algae that live within hosts, as do many Symbiodinium spp., these effects can dictate survival of entire ecosystems such as coral reefs. The production of the compound dimethylsulfoniopropionate (DMSP) may be responsible for differences in survival between algal species, and its link to the release of the climatically active gas, dimethylsulfide, imparts a potential global importance. DMSP has many proposed physiological functions in the algal species which produce it. This study examines the potential of DMSP to serve as an antioxidant in the zooxanthellae, Symbiodinium microadriaticum (CCMP1633) isolated from a cnidarian host. Specifically, the study investigates the synergistic effects of increased temperature and CO2 on the production of this compound in algal cultures. Preliminary data support an antioxidant role of DMSP in these algae, with significant changes in the concentration of DMSP at higher temperature. Activity of the enzyme methionine synthase will be monitored to determine whether production of methionine, a direct precursor to DMSP, is a point of regulation in an oxidative stress response. The findings of this study will provide mechanistic insight into the differential survival of cnidarian species and their algal symbionts under oxidative stress.
Ragland, J.M. (GPMB, College of Charleston), Arendt, M.D. (SC DNR) and Keller, J.M. (NIST)
Threats represented by organohalogen (OH) contaminants remain largely a mystery for threatened loggerhead sea turtles (Caretta caretta). This study examines regional-scale differences in OH concentrations and patterns in the blood plasma of adult male C. caretta. Turtles selected were tracked for an average of 140 days; one group (n=9) remained in the capture vicinity near Cape Canaveral, FL while another group (n=10) migrated northward along the eastern US coast becoming localized at numerous locations between South Carolina and New Jersey. Samples were analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) using gas chromatography mass spectrometry. While concentration variability and non-detect percentages were high, blood plasma concentrations from north-bound migratory adult male C.caretta were elevated compared with those remaining near Cape Canaveral for ΣPCBs (p=0.07), 4,4’-DDE (p=0.02), and ΣPBDEs (p=0.02). PBDEs were routinely detected only in migratory adults with PBDE 154 as the dominant congener. Typically, PBDE 47 is the dominant congener reported in wildlife. Atypical PBDE patterns have, however, been observed previously in reptiles captured 35-40ºN in the U.S. Interestingly, migratory males swimming northward settled largely in this latitudinal range. This study lends support to the idea that foraging location can have a dramatic effect on exposure to OH contaminants in highly mobile species such as C.caretta. Understanding contamination patterns will inform managers about possible health risks to certain subpopulations. In addition, this particular study is to our knowledge the first to couple satellite tagging with measurements of OH contaminants in the rarely studied adult male C. caretta.
Reiss, K.L. (GPMB, College of Charleston, NIST), Kucklick, J.R. (NIST), Keller, J.M. (NIST), Strand, A.E. (College of Charleston) and Gelsleichter, J. (UNF)
Bonnethead (Sphyrna tiburo) and finetooth (Carcharhinus isodon) sharks use estuaries in South Carolina and Georgia as nurseries and may become exposed to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). These contaminants are bioaccumulative, persistent, and ubiquitous in the environment particularly in association with developed areas. Due to their lipophilic nature, they are usually accumulated in organs such as the liver or fat tissue. The liver can metabolize the contaminants into hydroxylated compounds using the cytochrome P450 enzyme system. Previous studies have shown that hydroxylated PBDEs and PCBs can bind to transport proteins such as transthyretin or albumin while in the blood. These transport proteins are responsible for carrying thyroid hormones and other signals to their specific targets. Hydroxylated metabolites bind to carrier proteins more strongly than thyroid hormones and may cause thyroid gland disruption which could alter growth, development, or metabolism. Approximately eighty sharks have been sampled from four estuaries in South Carolina and two estuaries in Georgia through each state’s Department of Natural Resources (DNR). Samples will be brought back to the National Institute of Standards and Technology (NIST) Organic lab located inside the Hollings Marine Lab in Charleston, SC to quantify the parent PCBs and PBDEs as well as hydroxylated metabolites. A subsample of plasma will be sent to a collaborator at UNF to look at the thyroid hormone concentrations by using an ELISA assay. This study will assess the parent PBDE and PCB concentrations, their hydroxylated metabolite concentrations, and examine possible effects on the thyroid gland.
Stavovy, J. (GPMB, College of Charleston), DiTullio, J. (College of Charleston) and Sedwick, P. (Old Dominion University)
The Ross Sea is the single most productive region in the Southern Ocean. Many oceanic-atmospheric interactions that dictate climate processes are mediated by phytoplankton here. Due to the projected increase in atmospheric CO2 during this century, associated increases in precipitation, sea ice melt, and ocean stratification are foreseen. How these increases will affect carbon sequestration in the Southern Ocean remain unclear. An associated decrease in nutrient flux across the pycnocline may reduce the downward flux of carbon by causing a shift in phytoplankton community structure; currently, Phaeocystis antarctica and several species of diatoms dominate the Ross Sea. Algal blooms vary in time and space, with P. antarctica typically blooming early in the austral spring, and diatoms tending to dominate during the summer. The source of this temporal and spatial variation may be iron (Fe), since it is often limiting in these waters during the growing season. Historically, phytoplankton Fe requirements for growth have been assigned a fixed value. However, P. antarctica’s Fe requirement for growth has recently been shown to change as a function of irradiance. This study aims to determine the effects of irradiance on the Fe requirements of a sea-ice diatom, Fragilariopsis cylindrus. The half-saturation constant for growth with respect to Fe (Ku) will be determined at sub-optimal, optimal, and supra-optimal irradiance conditions for this species. In addition, certain physiological parameters such as photosynthetic efficiency, pigment composition, and intracellular dimethylsulfoniopropionate (DMSP) concentrations will be measured. These values are important in generating numerical biogeochemical models in the Southern Ocean.
Sturgeon, N. (GPMB, College of Charleston), Powel, J. (NOAA, NOS), Pate, M. (NOAA, NOS), Speakman, T. (NOAA, NOS), Coomer, K. (NOAA, NOS) and McFee, W. (NOAA, NOS)
The Atlantic blue crab (Callinectes sapidus) fishery has been implicated in a significant number of entanglements, and the gear used is known to have caused injury and death to bottlenose dolphins (Tursiops truncatus) throughout the southeastern United States. In order to study this fishery interaction, boat-based surveys were carried out in Charleston Harbor, SC from April through October 2008. Observations were conducted for 313h over 3604.8km along an established transect. During these surveys 2696 dolphins were sighted, 9425 buoys were observed and mapped, and dolphins were observed within 5m of 104 buoys. Dolphins were observed participating in a number of hypothesized behaviors believed to increase the risk of entanglement, including a behavior in which the crab pot buoy is fully submerged by direct interaction with the pot or buoy line. This behavior appears to be spatially and temporally clustered. GIS mapping was used to evaluate location and density of pots, location of historical entanglements, and location of observed interactions. Photo-identification is currently being conducted to investigate the identity and demographics of individual animals observed in the vicinity of, or interacting with, crab pots. Interviews of local crab fishers are being conducted to determine whether behaviors, such as pot tipping, implicated in other regions are occurring near Charleston, and to collect data regarding dolphin behaviors around the fishery’s pots and boats to additionally assess the impact of dolphins on pots and catch. Results of this study will be used to formulate recommendations for managing dolphin interactions with the blue crab fishery.
Wham, D. (GPMB, College of Charleston)
Coral reef ecosystems are undergoing global decline due to multiple stressors at local to global scales. Furthermore, it is clear that reefs in close proximity to humans are experiencing the most deleterious effects. The reef systems off of South Florida’s coast are near densely populated centers of human activity and it has been demonstrated that land-based sources of pollution are negatively affecting their vitality. While there has been more than an 80% coral cover loss across the Caribbean, the losses in South Florida have far surpassed these basin-wide estimates. Presently, living coral cover is between 1 and 3 percent, a mere remnant of earlier days. The effects of this loss at the population genetic level were explored using two microsatellites to investigate genetic diversity in Porites astreoides Lamarck, commonly called the mustard hill star coral. A comparison of populations from South Florida and the Bahamas revealed that while the two populations shared a large percentage of alleles, the Bahamian population possessed a greater number of alleles at both loci. Additionally, allelic diversity was reduced in the Florida population suggesting that the reduction in coral cover may also be accompanied by genetic bottlenecking.
Wilkie, J. (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. Many studies conducted within the surf zone have depicted snap shots of this dynamic community. Data from these short time spans are inadequate for describing long term trends. A study was conducted on Folly Beach, South Carolina from July 2007 to March 2009. In order to evaluate long term changes to the macrofauna in the surf zone, the findings were compared to a historic study conducted in the same location from 1969 to 1971. Data collected were analyzed to compare species richness and abundance between studies as well as between seasons. Over 21 months, 83 hauls were pulled and 1757 specimens were collected consisting of 109 swimming invertebrates and 1648 fishes. These organisms represented 40 species (10 invertebrate, 30 fishes), 30 genre (7 invertebrate, 23 fish) and 19 families (3 invertebrate, 16 fish). Species richness and abundance was significantly higher during the summer of 2007 than all other seasons sampled in this study. The species richness was significantly lower than found in the historic study. The abundance caught was also significantly lower than in the previous study for every season except spring. Additional analyses will examine any correlations between abundance or biomass and any of the physical measurements collected.
Williamson, T.J. (GMBP, College of Charleston) and Zardus, J.D. (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 was used to characterize the genetic variation of populations of M. coccopoma along the southeastern coast of the US. Analysis yielded high genetic diversity with low nucleotide diversity. The near absence of genetic structure suggests a panmictic population with high larval dispersal; however, six individuals from a single population in Florida were genetically distinct, suggesting the possibility of multiple invasions. 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.