Baxter, S. (MES, College of Charleston); Hart, L. (NOAA); Balmer, B. (Mote Marine Laboratory); Shervette, V. (USC); Zolman, E. (NOAA) and Ali, A. (College of Charleston)
Epidermal diseases in cetaceans are geographically widespread and highly prevalent; however, factors contributing to the presence of lesions are poorly understood. Skin lesions can be caused by multiple bacteria, viruses and fungi and have previously been linked to environmental (i.e. water temperature and salinity) and anthropogenic (i.e. pollution and contaminants) factors. This study evaluates the association of environmental and anthropogenic factors with the presence of skin lesions on bottlenose dolphins (Tursiops truncatus) in coastal, Georgia. This region experiences large fluctuations in water temperature and salinity and studies have demonstrated high concentrations of polychlorinated biphenyl (PCB) contaminants among marine wildlife, including dolphins in waters near Brunswick and Sapelo, Georgia. Bottlenose dolphin photo-identification (photo-id) data from 2008 and 2009 will be used to detect the presence of lesions, while statistical analyses (i.e. t-test, logistic regression, Chi-Square/Fisher Exact tests) will be used to examine associations with previously measured PCB concentrations in blubber, as well as water temperature and salinity data collected during photo-id sightings. It is expected that the probability of skin lesion occurrence will be higher for dolphins sighted in waters with lower temperatures and salinities and among dolphins with higher concentrations of PCBs. The prevalence of skin lesions among dolphins sighted in Brunswick and Sapelo, Georgia is also expected to vary by season and sighting location. The results of this research will provide evidence that skin lesions can serve as indicators of a changing environment or anthropogenic contamination.
Bezy, V. (GPMB, College of Charleston) and Plante, C. (College of Charleston)
The olive ridley sea turtle population at Ostional, Costa Rica exhibits mass nesting events (arribadas) estimated at up to 500,000 nesting females over a period of only seven days. Despite the large population of nesting females, concern remains that the low hatching success (8%) at this beach is not enough to sustain the population long-term. Several studies have suggested that embryo mortality is associated with the high microbial load resulting from the decomposition of eggs broken by subsequent nesting turtles due to the high nest densities characteristic of arribada events. Thus, a legalized community-based egg harvest program is aimed at reducing the number of nests destroyed while providing the funds to support local infrastructure and family income. However, no previous research has directly quantified microbial load and the associated direct and/or indirect effects on hatching success in situ. This study aims to determine the impact of microbial load on hatching success by monitoring natural nests and applying experimental treatments to reduce the microbial load of the sand into which nests are relocated. Temperature, oxygen, and organic matter content will be monitored throughout the incubation period. The microbial load of nest sand will be quantified and characterized using qPCR and DGGE molecular analysis. Should experimental treatments successfully increase hatching success, this could be applied as a management technique to improve hatching success. This study will help identify a relationship between hatching success and the microbial community of the sand while ensuring the sustainability of the egg harvest as a conservation strategy.
Bridges, C. (GPMB, College of Charleston) and Galloway, S. (NOAA)
Though little is known of coral immune mechanisms, it has been suggested that localized, non-normal pigmentation in compromised tissues may reflect an innate inflammation-like response; in Porites spp. this pigmentation appears pink. A prior investigation in Porites compressa reported a red fluorescent protein (RFP) (Emax: 590 nm) produced and localized in pink tissue infected with trematodes. We identified a unique bright RFP associated with pink pigmented tissue bordering circular lesions on Porites lobata specimens; the protein produced a red fluorescence with an Emax of 612 nm following green excitation (540nm). Not only is our RFP further red- shifted than the furthest wild-type coral fluorescent protein, eforCP/RFP (Ex: 609 nm), it is substantially brighter (~100 fold) than the native GFP in Porites lobata. Furthermore, histological observations illustrate a localization of melanin-containing chromophore cells (a general immune response) around epidermal cells with red fluorescence and infiltration of melanin granules into the epidermal tissue. As our unique RFP is closely associated with evidence of this stress response at the cellular level, its use as an optical marker in Porites lobata could allow for early detection of stress. We plan to isolate a clone of the RFP from a cDNA library constructed from tissue samples with the pink TPR, record the protein spectral properties, determine its structure, establish homology to other Anthozoan GFP-like proteins, and confirm localization of RFP to the areas of pink pigmentation. Such properties will provide insight into the connection of the RFP with this stress response mechanism and its potential as a diagnostic tool.
Coles, D. (GPMB, College of Charleston)
Gray’s Reef National Marine Sanctuary is an important Marine Protected Area, established in 1981 with the aim of benefiting fisheries, and the marine biota more generally. The site was selected based on its abundance of live-bottom habitat – a critical habitat type that harbors a disproportionate amount of marine life in the subtropical region. Despite a general consensus that the sanctuary is an important location for fish spawning, no spawning has been documented there to date. One possible explanation is that, while GRNMS has been studied intensively, research has largely been limited to midday, missing critical dawn and dusk windows of spawning activity. The proposed research will attempt to fill in this knowledge gap and document fish spawning at GRNMS. The focal species will be the scamp grouper, Mycopterca phenax, but other species of the snapper-grouper complex will also be examined. SCUBA observation and video recording and analysis will be performed, focusing on dusk during full and new moons; research has shown that many serranidae species time their spawning to coincide with the strong tides associated with these phases of the lunar cycle. The results of this research will be useful for GRNMS managers as well as fisheries managers throughout the region. By determining where and when fish spawn, more strategic decisions can be made regarding (1) future establishment of MPAs (2) temporal fisheries closures that protect fish during spawning periods, and (3) enhanced fishing regulations within specific “hotspots” at GRNMS or other MPAs. By identifying spawning locations, conditions, and times, and taking appropriate management steps in response, local and regional fish stocks may be enhanced, allowing increased maximum sustainable yield (MSY).
Crawford, C. (GPMB, College of Charleston) and Naylor, G. (College of Charleston)
Chondrichthyans (sharks, rays, skates, and chimaeras) are highly diverse and inhabit bodies of water all over the world, from the tropics to polar seas, some even inhabit freshwater lakes and rivers. Chondrichthyans have been around for about 450 million years, however modern sharks, the Neoselachii, have inhabited the seas for 200 million years. This project will use Computed Tomography (CT) Imaging to explore morphological variation across 50-80 phylogenetically diverse species of Chondrichthyans. The observed variation in skeletal anatomy deduced from segmented CT scan data will be interpreted within the context of a recent estimate of phylogenetic relationships based on molecular data. Focus will be on morphology of the skull, gill arches, jaws, pelvic girdle and pectoral girdle. This project will be part of a collaborative effort to develop a phylogenetic tree of life of modern Chondrichthyans.
Day, H. (GPMB, College of Charleston) and Owens, D. (College of Charleston)
Currently the status of the Diamondback Terrapin, Malaclemys terrapin, is unknown or declining throughout much of their range. Anthropogenic threats to terrapin populations include loss of suitable nesting habitat, road mortality, and mortality in commercial and recreational crab traps. A previous study has estimated a robust population size of approximately 3000 terrapins in the Ashley River, however more data regarding the status of the Diamondback Terrapin in the Charleston area is required to evaluate population trends and recruitment levels. Terrapins will be captured throughout Charleston Harbor using trammel netting and seine netting. Individuals will be dual marked using PIT tags and marginal scute notching. Multiple tagging techniques will be employed to evaluate the efficacy of PIT tagging for mark-recapture studies in the Diamondback Terrapin. Population estimates generated from mark and recapture data will be calculated using MARK software. Sex ratios will also be determined. This information on the population size, sex ratios, and distribution of terrapins can be used to evaluate the status of the terrapin populations in Charleston, South Carolina and help to determine if implementation of new management measures should be considered.
Derex, R.L. (GPMB, College of Charleston), Burnett, L.E. (College of Charleston), Burnett, K.G. (College of Charleston)
Across most animal phyla, the response to acute environmental hypoxia is observed in several tissues and includes changes in many cardiovascular and respiratory parameters. In addition, chronic hypoxia elicits widespread changes in gene transcription and protein synthesis. Recent studies have implicated H2S as the beginning of a broad cell signaling cascade which facilitates the global response to hypoxia in all vertebrate classes; however, this has not been investigated in invertebrates, and is of particular interest with regard to estuarine invertebrates as they experience severe hypoxia on a daily basis and live in a relatively H2S-rich environment. The first objective of my study is to test whether H2S can trigger an acute response to hypoxia in the Atlantic blue crab Callinectes sapidus. The frequency of scaphognathite beats, the frequency and duration of ventilatory pauses, and unilateral/bilateral beating patterns of scaphognathites will be measured in crabs acclimated to normoxia, then acutely exposed to environmental hypoxia or to H2S under normoxic conditions. As a second objective of this study, crabs will be dosed with specific inhibitors of the H2S -producing enzymes cystathione β-synthase, cystathione γ-lyase, and 3-mercaptopyruvate sulfurtransferase to confirm the involvement of H2S in the response to acute hypoxia. A third objective is to quantify changes in the gene transcripts and enzymatic activity of the H2S-producing enzymes in crabs exposed to normoxia or chronic hypoxia. Evaluating the potential for H2S to act as a signal will provide valuable insight to the mechanisms underlying stress responses. Supported by NSF IOS-1147008.
Doty, S.M. (GPMB, College of Charleston), Kingsley-Smith, P.R. (SCDNR), Morris, Jr., J.A. (NOAA), Harold, A.S. (College of Charleston), and Sancho, G. (College of Charleston)
The Indo-Pacific lionfish (Pterois volitans / miles) is an invasive marine fish that has become established in the Caribbean Sea, Gulf of Mexico, and western North Atlantic Ocean along the southeast coast of the United States. Lionfish have long, venomous spines in their dorsal, pelvic, and anal fins that serve as a defense against potential predators, and are known to be voracious, opportunistic predators that consume a variety of invertebrates and small reef fishes. Accordingly, several studies have shown that the presence of lionfish can significantly reduce reef fish abundance, diversity, and recruitment.
The original proposal was intended to investigate the diet composition of lionfish on South Carolina artificial reefs. After two sampling seasons and one year of study, however, insufficient samples quantities have been obtained locally (n < 20). As a new approach, samples (n > 1100) collected from Biscayne National Park (BNP) since June 2010 have now been provided by collaborators from the National Park Service, providing sufficient material to investigate questions regarding the relationships between lionfish diet and habitat type.
This will be the first lionfish study specifically targeting BNP. The study site encompasses a wide variety of habitats including shallow patch reefs, deep shelf ledges, wreck sites, and anthropogenic structure. Using BNP benthic mapping data in conjunction with lionfish stomach content analyses, lionfish diet will be characterized by fish size and habitat to provide a better understanding of the ecology of lionfish within the Park and to inform future lionfish management decisions.
Hook, W. (GPMB, College of Charleston)
Bacterial abundances in sediments remain remarkably consistent across broad geographic and environmental ranges despite the distributive heterogeneity of species on a millimeter scale. In intertidal sediments, the majority of bacteria live in mixed-species biofilms attached to sediment grains. These particle-associated bacteria subsist in higher densities and with greater species diversity than their free-living counterparts, resulting in the frequent occurrence of bacterium-bacterium interactions. One mechanism that may contribute to the spatial partitioning of species and allow for the coexistence of direct competitors is antagonism among bacteria. The secretion of antibiotics, which inhibit or kill adjacent cells, is a characteristic form of inter-specific competition. Of the 200 bacteria isolated from intertidal sediments and screened using a disc-diffusion assay, 40% displayed the ability to produce inhibitory compounds, whereas significantly fewer porewater-associated bacteria (25%) produced antimicrobials. A subset of the antimicrobial-producing bacteria and designated environmental target strains were selected to establish relative in situ abundances. Denaturating gradient gel electrophoresis (DGGE) was used to identify these model bacteria within whole-community environmental samples. By sequencing a region of the 16S rRNA gene, the presence and environmental relevancy of the antibiotic-producers was confirmed. These bacteria will be employed in a series of competition experiments conducted in laboratory microcosms. Analysis by quantitative PCR with species-specific primers should elucidate the role of pre-emptive and interference competition in structuring benthic microbial communities.
Kelly, A. (GPMB, College of Charleston) and Shervette, V. (University of South Carolina Aiken)
Gray triggerfish Balistes capriscus is a commercially and recreationally-valued reef fish species. Over the past five years, average annual landings are approaching 700,000 lbs in U.S. Atlantic waters. Gray triggerfish are managed as part of the South Atlantic snapper grouper complex fishery. Many of the other species in the snapper grouper complex, including red snapper and gag grouper, are considered overfished and are being tightly regulated which has led to increased fishing pressure on alternative species including gray triggerfish. Despite the economic importance of this species, no published information exists concerning age, growth, and reproductive biology in Atlantic waters of the U.S. Fortunately, the Marine Resources Monitoring, Assessment, and Prediction (MARMAP) Program at SCDNR has been collecting life history data for this species as part of its reef-fish monitoring program over the past several decades. For the current study, we are working with MARMAP to process age and reproduction samples from gray triggerfish in order to obtain the following objectives for the South Atlantic Bight population of this species: 1. Determine growth rates, population age structure, and sex ratios, and 2. Determine reproductive seasonality, size, and age at maturity. This information will be utilized in ongoing gray triggerfish stock assessment efforts by the South Atlantic Fisheries Management Council and the National Marine Fisheries Service.
Kollars, N. (GPMB, College of Charleston), Byers, J. (University of Georgia), and Sotka, E. (College of Charleston)
Multiple hypotheses have been proposed to explain the establishment of an introduced species in a novel habitat. Among these, the role of negative species interactions (eg., the ability to outcompete native species or escape natural predators in the introduced range) has dominated our understanding of species invasions. However, positive interactions may also be fundamental in driving invasions. Novel marine mutualisms are rare but one example may be the association between the introduced seaweed Gracilaria vermiculophylla and the native decorator worm Diopatra cuprea. In the estuaries of the southeastern US, Diopatra attaches Gracilaria drift fragments to its tube which facilitates Gracilaria by anchoring the alga in a favorable photic zone and promoting asexual fragmentation. Preliminary field evidence suggests this association is also beneficial to Diopatra either because Diopatra is farming the alga for the small prey the seaweed attracts or because the seaweed itself is a novel food source. We are also using microsatellites to document the alga’s invasion history. We generated a microsatellite library using 454 next-generation sequencing technology and loci are currently being screened for polymorphism. Tracking the invasion history of Gracilaria would provide insight into the genetic variation present in introduced Gracilaria populations and consequently indicate the evolvability of the invader in response to selective forces in the novel habitat. The results of these combined efforts will advance our understanding of the role of species interactions in invasion systems and provide baseline data on the ecological impacts of the Gracilaria invasion to marine communities in the southeastern US.
Leidig, J. (GPMB, College of Charleston)
Black drum is an estuarine dependent saltwater fish that supports recreational and commercial fisheries throughout the US Atlantic coast and the Gulf of Mexico. Life history traits have been described throughout its geographical range, but differences exist for some characteristics between regions, which leads to the question of whether there are regional sub-populations of black drum. The data on black drum in South Carolina have primarily been collected as supplemental data from South Carolina Department of Natural Resources (SCDNR) fishery independent and fishery dependent surveys. However, these data are limited, especially for adult black drum. Only one previous study has examined population structure of black drum using mitochondrial DNA and limited samples from the Atlantic. The current study will use microsatellite markers of nuclear DNA to examine genetic variation of black drum along the Gulf of Mexico and US east coast to determine if different subpopulations exist. Life history data will also be collected, including size and age at maturity, reproductive biology, growth, and population age structure. This additional data would be necessary to perform an adequate age-based stock assessment. Data from this study will prove useful for management and conservation of this species. Knowledge of population structure will allow for accurate definition of geographic boundaries to determine useful management units. Life history information from South Carolina can be used to better manage the population’s resilience to current fishing pressure.
Lytton, A. (GPMB, College of Charleston), Reichert, M. (SCDNR), Ballenger, J. (SCDNR), Smart, T. (SCDNR)
Wreckfish, Polyprion americanus, is a commercially important long-lived demersal fish, occurring throughout the Atlantic. Wreckfish can be found in the eastern Atlantic from Norway to South Africa; including the Mediterranean, Canary Islands, Azores, Bermuda, and Madeira, and along the western north Atlantic from Grand Banks, Newfoundland to La Plata River, Argentina. Despite the wide geographic range, recent DNA evidence distinguishes a northern Atlantic and southern Atlantic population. Commercial fishing for wreckfish takes place throughout its north Atlantic range, with the exception of Bermuda. In the western North Atlantic the fishery is considered a success story of fisheries management. Despite this fact, important information is missing, preventing competent management of the fishery. For instance, age estimates for the north Atlantic wreckfish have not been validated, possibly leading to inaccurate estimates of length at age, maximum age, and various related biological parameters. Furthermore, little is known about the early life history of juvenile north Atlantic wreckfish. This study proposes to use bomb radiocarbon to validate the age determination in this long-lived species. Once the ages have been validated, we will determine the proper natural mortality rate to be used in stock assessments and estimates of annual catch limits. In addition, back-calculated growth rates will be used to characterize early life history traits. Finally, growth parameters will be estimated based on updated age information. Confirming aging techniques and improved estimates of life history parameters, will allow for proper management of the species, as well as maximize a sustainable economic return from the fishery.
Mortensen, R. (GPMB, College of Charleston), Greenfield, D. I. (USC/SCDNR), and Arnott, S (SCDNR)
Red drum, Sciaenops ocellatus is an economically important finfish found in the Atlantic Ocean from Massachusetts through the Gulf of Mexico, and is common along South Carolina's shores where recreational fishermen regularly catch this species. S. ocellatus does not sustain a commercial fishery, and fundamental knowledge about its life history needed to accurately determine stock is lacking. Egg production indices can estimate standing stock biomass of a species when information about breeding adults is relatively unknown. Egg identification for S. ocellatus and related species typically entails microscopy, a time consuming and imprecise method relying on species-level identification of eggs based on morphological differences, and these distinctions may not become apparent until 24 hours after hatching. Sandwich hybridization assay (SHA) is a molecular method that allows species or taxa-specific identification by direct detection of unpurified and unamplified large subunit (LSU) ribosomal RNA (rRNA) and has been successfully used to identify and quantify numerous planktonic taxa including harmful algal bloom species, zooplankton, invertebrate larvae, and bacteria. SHA utilizes two oligonucleotides, a signal probe and species or taxa specific capture probe, conjugate and enzyme substrate that produces a colorimetric response, the intensity of which is directly proportional to the LSU rRNA in a homogenate. Results from sequencing of LSU rRNA for S. ocellatus and other closely-related Sciaenids indicated low genetic divergence and only one polymorphic site for S. ocellatus, so capture probe design efforts are currently focused on the more variable ITS region, which shows promise.
Reed, M. (GPMB, College of Charleston) and Greenfield, D. I. (University of South Carolina & SCDNR)
Human population density, and therefore urbanization, is predicted to increase rapidly along South Carolina’s (SC) coast over upcoming decades, which will undoubtedly affect estuarine nitrogen (N) and phosphorus (P) levels. In preparation, SC regulators are establishing numeric criteria for nutrients in the coastal zone. These thresholds should account for biological responses to various N and P forms and concentrations. This project examines how different forms of N, with or without P, influence phytoplankton biomass and community composition among four coastal SC habitats: a forested tidal creek in Winyah Bay, an urbanized tributary to the Ashley River, a salt marsh in the Combahee River, and a stormwater detention pond on Kiawah Island. Phytoplankton biomass and community composition responses to N and P will be assessed via seasonal field sampling and nutrient addition bioassays over two years (2011-2013). For the latter, surface water samples are inoculated with 9 treatments: 1) no addition (control), 2) nitrate, 3) ammonium, 4) urea, 5) orthophosphate, 6) nitrate + orthophosphate, 7) ammonium + orthophosphate, 8) urea + orthophosphate, 9) all. N and P are added at Redfield ratios (16 : 1) as 20 µM N and 1.25 µM P. Fluorometric analyses of chlorophyll a will be used to calculate phytoplankton biomass. High performance liquid chromatography (HPLC) pigments will be analyzed using CHEMTAX to determine relative abundances of algal taxa. Finally, coastal SC is rich in terrigenous dissolved organic carbon (DOC), which fuels microbial respiration and can contribute to hypoxia. Therefore, DOC and bacterial abundances will be assessed.
Smylie, M. (GPMB, College of Charleston), Shervette, V. (University of South Carolina Aiken), McDonough, C. (South Carolina Department of Natural Resources), Owens, D. (Grice Marine Laboratory), and Reed, L. (National Oceanic and Atmospheric Association-National Ocean Service)
Though mercury (Hg) occurs naturally, anthropogenic emissions have increased atmospheric Hg levels by an estimated factor of three since the Industrial Revolution. This has caused corresponding increases in Hg levels in terrestrial and aquatic ecosystems. Wetlands contribute to transformation of elemental mercury into its most toxic form, methylmercury (MeHg), by anaerobic sulfur-reducing bacteria and serve as a pathway for Hg from freshwater to the marine environment. Effects of this neurotoxin vary based on a species’ susceptibility and degree of exposure, while concentrations in fishes depend on the conditions in which they live. A better understanding of Hg uptake patterns and retention will help equip fisheries managers to make decisions regarding catch rates in light of potential human health risks. Biological factors affecting bioaccumulation and biomagnification include diet, trophic level, age, physiology, and size. Environmental factors include pH, salinity, dissolved organic carbon, rate of Hg addition, and temperature. Longnose gar (Lepisosteus osseus) provide an excellent model to study how fishes take up Hg along a salinity gradient over time in estuaries due to their extensive range, high abundance, top predator status, and tolerance for a range of salinities. The present study examines patterns of Hg accumulation within muscle tissue of longnose gar from the Ashley River and Winyah Bay in South Carolina with regard to salinity, size, sex, age, diet, and reproductive stage. In addition, health parameters, including growth rate, reproductive output, and body condition, will be examined to determine if Hg produces harmful effects in longnose gar.
Song, S. (GPMB, College of Charleston), Burnett, L. (College of Charleston), and Burnett, K. (College of Charleston)
Bacterial infection counts among an assortment of stressors for estuarine organisms, but with a concentration of 6×105 bacterial cells per mL of seawater, should not be overlooked. The effects of bacterial infection on locomotion in any marine organism is of notable ecological importance because of the relationship between locomotory ability and feeding, predator avoidance, migration, and reproduction. Shrimp have three forms of locomotion: walking, swimming, and tail-flipping. Although they spend the majority of their time on the benthos, there is a dearth of information on the physiology of shrimp walking. Our lab has constructed an underwater treadmill that has successfully been used to measure walking performance in the Atlantic blue crab, Callinectes sapidus. Using the Atlantic white shrimp, Litopenaeus setiferus, I will measure oxygen uptake during sustained walking exercise on a treadmill to see if there is a difference in aerobic scope between shrimp injected with saline (control) and shrimp challenged with an injection of a common marine bacterium. L. setiferus is an ecologically and economically important species in South Carolina. The bacterium of choice is Vibrio campbellii, known to be pathogenic to crustaceans and well-known in our lab. Previous work in our lab has shown that oxygen uptake is reduced in V. campbellii-challenged shrimp at rest, and respiratory fitness is reduced in challenged blue crabs while exercising. We expect that oxygen uptake and overall aerobic scope will be greatly reduced for exercising shrimp, when injected with V. campbellii. This research is supported by the National Science Foundation under Grant No. IOS-1147008.