GPMB September 2010 Colloquium:
Abstracts of Oral Presentations
THE EFFECTS OF IRON AND IRRADIANCE ON THE GROWTH AND PHYSIOLOGY OF THE POLAR DIATOM, FRAGILARIOPSIS CYLINDRUS)
Bennett, J. (GPMB, College of Charleston), DiTullio, J. (College of Charleston), and Sedwick, P. (Old Dominion University)
Because the Ross Sea is the most productive region in the Southern Ocean, many of the key oceanic-atmospheric interactions dictating climate are mediated by phytoplankton in this region. Algal blooms vary in time and space, with Phaeocystis antarctica typically blooming until mid-summer, and diatoms tending to dominate for the remainder of the growing season. The source of this variation may be iron (Fe), since it is often limited in these waters during this time. Because P. antarctica’s iron requirement for growth has been shown to change as a function of irradiance, this study aims to determine the effects of irradiance on the Fe requirements for growth of a diatom species, Fragilariopsis cylindrus. Initial irradiance experiments measured growth and physiological parameters of F.cylindrus acclimated to six light levels (20, 50, 75, 100, 150, and 300 µE·m-2·sec-1). The maximum specific growth rate (µmax) varied from 0.31 µ·d-1 at 20 µE·m-2·sec-1 to 0.41 µ·d-1 at 300 µE·m-2·sec-1. The photosynthetic efficiency of photosystem II (Fv/Fm) was greatest at 20 µE·m-2·sec-1 and lowest at 300 µE·m-2·sec-1 (0.41 and 0.14 respectively). Pigment composition did change with varying light regimes, although intracellular levels of reactive oxygen species within the cells were not significantly different among treatments. Intracellular dimethylsulfoniopropionate (DMSP) ) concentrations appear to decrease at higher irradiance levels. The half-saturation constant for growth with respect for iron (Ku) will now be determined at sub-optimal, optimal, and supra-optimal irradiance conditions. These values will contribute to the understanding of bloom dynamics and subsequently climate conditions in the Southern Ocean.
THE EFFECT OF SEDIMENT GRAIN SIZE AND SHELL CONTENT ON THE BURROWING RATE OF THE COQUINA, DONAX VARIABILIS
Bricker, T . (GPMB, College of Charleston) and Bergquist, D. (SCDNR)
The physical characteristics and the biological communities of the sandy beach can be significantly impacted by anthropogenic modifications of the coastal environment. The purpose of this study is to examine how changes in the amount and the size of the shell in sediments affect the burrowing ability of Donax variabilis, an abundant and ecologically important beach bivalve. D. variabilis were exposed to four different grain sizes of sand (very coarse, coarse, medium, and fine) and four different percentages of crushed oyster shell (0%, 25%, 50%, and 100%) in a full factorial lab-based experiment. The burrowing rate and burrowing behaviors of D. variabilis were observed for each combination of sand and shell. In these experiments, the burrowing rate of D. variabilis varied significantly due to increased grain size and shell content. Additional studies, currently underway, were designed to reflect changes to the beach sediment that accompany human impacts. In one experiment, D. variabilis were exposed to shell of a larger grain size. To determine if increasing shell content results in differences in D. variabilis densities in a field setting, historical data from past statewide monitoring projects will be mined and analyzed. This study may provide a mechanism in explaining changes in the biological community as a result of changes in physical characteristics following human impacts.
IDENTIFICATION OF THE SPLICED LEADER RNA SEQUENCE AND RESPONSE TO HEAT SHOCK IN SYMBIODINIUM MICROADRIATICUM
Feltman, P. (GPMB, College of Charleston) and Van Dolah, F. (NOAA Center for Coastal Environmental Health and Biomolecular Research)
Coral bleaching, the breakdown of the symbiotic relationship between the cnidarian host and its dinoflagellate symbiont, is characterized by the loss of the symbiont from the host tissue. Increased temperature has been implicated as a major cause of coral bleaching; however the molecular mechanisms regulating this process are largely unknown. Spliced leader (SL) mediated trans-splicing has been identified in 15 dinoflagellate species, including the coral symbiont Symbiodinium microadriaticum. During SL trans-splicing, first described in trypanosomes, all RNA messages are trans-spliced with an identical leader sequence at their 5' end. Under conditions of severe stress, transcription of the SL RNA is shut off, a response termed spliced leader silencing (SLS). SLS leads to a reduction of SL trans-splicing and therefore, mRNA maturation and overall protein synthesis. This study seeks to determine whether SLS is part of the stress response in Symbiodinium. The SL gene transcript was amplified from Symbiodinium total RNA by PCR and found to be approximately 100 nt in length. Currently, this transcript is being sequenced and a quantitative PCR assay developed to identify if SLS occurs in Symbiodinium. Range finding experiments identified 33° C as an acute, sublethal stress. Under this condition, photosynthetic efficiency (FV/FM) was significantly reduced by 12h and remained low for at least 96 hr, while viability was unaffected. To assess for SLS, total RNA isolated from heat stressed cells will be quantified by qPCR for SL RNA expression levels. If SLS is involved in stress in Symbiodinium, it may provide a pre-bleaching stress marker.
EMBRYONIC DEVELOPMENT IN GASTROPOD EGG MASSES ASSOCIATED WITH A PHOTOSYNTHETIC SUBSTRATE
Fernandes, D.A.O. (GPMB, College of Charleston) and Podolsky, R.D. (College of Charleston)
Marine gastropods commonly deposit egg masses in association with photosynthetic organisms. As a consequence, photosynthesis can provide oxygen to embryos embedded within egg masses. However, little is known about how embryonic development is affected by this intimate association. In the present study, I used embryos of the intertidal gastropod Haminoea vesicula, which often attaches its egg mass to the eelgrass Zostera marina, to examine how developmental rate and hatchling shell size is affected by the association with a photosynthetic substrate. Pieces of egg masses were attached to eelgrass blades, 0.45µm filter pieces, or directly to the mesh of mesh-bottom plastic trays. The trays with the egg mass pieces were placed in outdoor tanks with flowing seawater. Embryos were raised under five different light conditions: 0%, 25%, 50%, 75% and 100% light. The association with eelgrass at 100% light accelerated development, whereas the presence of Z. marina at 0% light represented a cost to embryonic development time. The association with eelgrass did not affect hatchling shell length. Nonetheless, embryos hatched at smaller sizes at low light levels. A separate batch of egg mass pieces was collected before hatching for chlorophyll-a analysis. Chlorophyll-a content was used as a proxy for fouling of egg masses by photosynthetic microorganisms. Egg masses associated with eelgrass exhibited much lower chlorophyll-a contents under all light conditions. The presence of the macrophyte Zostera marina not only accelerated embryonic development under good light conditions but also reduced levels of fouling on the egg mass of Haminoea vesicula.
THE PRESENCE AND FATE OF PHARMACEUTICALS AND PERSONAL CARE PRODUCTS (PPCPs) IN WASTEWATER AND THE CHARLESTON HARBOR, SOUTH CAROLINA
Hedgespeth, M. (GPMB, College of Charleston), Burnett, L. (College of Charleston), Pennington, P. (NOAA/CCEHBR), Sapozhnikova, Y. (NOAA/CCEHBR), Wirth, E. (NOAA/CCEHBR)
PPCPs (pharmaceuticals and personal care products) are considered to be a group of emerging contaminants that includes 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 non-point and point sources including domestic wastewater treatment plant effluents. The presence of such emerging contaminants in aquatic environments creates possible risks for health impacts on non-target organisms. This study assesses seasonal/regional trends in the concentrations of PPCPs and hormones in wastewater and surface waters, as well as removal efficiencies of the wastewater treatment process. Beginning in April 2009, we examined monthly chemical concentrations of nineteen commonly used PPCPs and hormones in influent and effluent collected from two local domestic wastewater treatment facilities, as well as surface water samples collected in the Charleston Harbor. Upon analysis using HPLC/MS/MS, results suggest clear differences in concentrations among influent, effluent, and surface water samples. Eleven of the nineteen target compounds were detected above minimum reporting levels in wastewater influent, nine in effluent, and seven in surface water samples. The concentrations were reduced by more than 90% for most chemicals in effluents in comparison to influents and much lower in surface water samples compared to wastewater samples. Upon completion, this one-year monitoring 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 the presence of PPCPs in the marine environment.
CHARACTERIZATION OF THE BACTERIAL PROPERTIES THAT IMPAIR RESPIRATION IN THE ATLANTIC BLUE CRAB, CALLINECTES SAPIDUS
Johnson, N. (GPMB, College of Charleston), Burnett, L. (College of Charleston), and Burnett, K. (College of Charleston)
In the blue crab Callinectes sapidus, injection with the bacterial pathogen Vibrio campbellii causes a decrease in oxygen consumption. Histological and physiological evidence suggests that the physical obstruction of hemolymph flow through the gill vasculature, caused by aggregations of bacteria and hemocytes, underlies the decrease in aerobic function associated with bacterial infection. We sought to elucidate the bacterial properties sufficient to induce a decrease in circulating hemocytes, reflecting hemocyte aggregation and the decrease in respiration. Lipopolysaccharide (LPS), the primary component of the Gram negative bacterial cell wall, is known to interact with crustacean hemocytes. Purified LPS was covalently bound to the surfaces of polystyrene beads, resembling bacteria in size. Injection of these “LPS beads” caused a decrease in circulating hemocytes comparable to that seen with V. campbellii injection, while beads alone failed to do so. These data suggest that a wide range of Gram negative bacteria could stimulate hemocyte aggregation. To test this hypothesis, crabs were injected with different bacterial species—six Gram negatives and one Gram positive—and their effects on circulating hemocytes were assessed. With one exception, all Gram negatives caused decreases in circulating hemocytes. Differences could be explained by variation in structure and content of LPS across bacterial species. However, LPS is not necessary to provoke the immune response, as Bacillus coral, which lacks LPS, caused a decrease in circulating hemocytes. To better understand the metabolic and energetic costs of mounting an immune response, future studies will explore the relationship between hemocyte aggregation and decreased respiration.
A NOVEL SAMPLING METHOD FOR INVESTIGATING UTILIZATION OF NATURAL, RESTORED AND ENHANCED OYSTER REEF HABITATS BY NEKTONIC ORGANISMS
Joyce, R. (GPMB, College of Charleston), Kingsley-Smith, P. (SCDNR-MRRI), Roumillat, B. (SCDNR-MRRI), Reichert, M. (SCDNR-MRRI) and Arnott, S. (SCDNR-MRRI)
Most previous studies documenting the role of South Carolina’s intertidal oyster reefs in providing habitat for nektonic organisms have used trawls, habitat trays and lift nets to compare the species assemblages associated with different habitat types. These sampling methods, while effective, involve some degree of habitat disturbance. For this study, a novel, non-destructive sampling method was developed that releases a suspended stop-net, rapidly encircling the nektonic organisms present in study plots at high tide. As the tide recedes, nektonic organisms are collected, identified, enumerated, measured and wherever possible released alive. This method was employed to compare the nektonic assemblages associated with intertidal oyster reefs with those of neighboring soft sediment habitats at three sites in South Carolina. Each site comprises two 120m2 study plots; an experimental plot of structurally-complex habitat and an adjacent control plot that lacks structural complexity. Experimental plots differ in substrate type (oyster “castles”, oyster shell bags, and natural oyster reef) and age (1 to 7+ years) across sites. Sampling began in February 2010 and will continue through November 2010, targeting daytime negative low tides. Higher abundances of nektonic organisms have been observed in experimental plots compared to control plots and nekton abundances have generally increased over time with increasing water temperature. Higher species diversity has been observed for the experimental plot at two of the three study sites. At the third site, nekton diversity has not differed significantly between treatments. Variation in nekton diversity across sites for the experimental plot may be explained by habitat age.
OCCURRENCE OF HYDROXYLATED ORGANIC CONTAMINANTS AND OTHER ORGANOHALOGEN COMPOUNDS IN SHARK BLOOD PLASMA FROM THE SOUTHEAST COAST OF THE U.S.
Reiss, K. (GPMB, College of Charleston), 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 along the Southeast coast as nursery areas and may become exposed to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) as well as other organohalogenated compounds. These contaminants are bioaccumulative, persistent, and ubiquitous in the environment. 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 methoxylated compounds followed by demethoxylation into hydroxylated metabolites. The chemicals can then enter the blood stream where they may persist and interfere with the endocrine system especially with thyroid hormones. Disruption of the thyroid gland could potentially affect growth, development, or metabolism in these animals. Shark blood and muscle tissue were sampled from five estuaries in South Carolina, two estuaries in Georgia, and one estuary in Florida to examine contaminant concentrations. Approximately 148 persistent organohalogen compounds were determined along with 23 hydroxylated PCBs (OH-PCBs), hydroxylated PBDEs (OH-PBDEs), and halogenated phenols using gas chromatography and mass spectrometry. Quantifiable levels of OH-PCBs and OH-PBDEs were detected in shark blood samples. This was the first study to examine concentrations of the hydroxylated PCBs and PBDEs in shark blood plasma.
DETECTION OF AN ONTOGENETIC SHIFT IN THE DIET OF A HEAVILY EXPLOITED SHARK SPECIES (CARCHARHINUS PLUMBEUS, NARDO 1827) USING MINIMALLY INVASIVE ∆13C AND ∆15N STABLE ISOTOPE ANALYSIS
Shiffman, D. (GPMB, College of Charleston), Frazier, B. (SCDNR), Kucklick, J. (NIST, Hollings Marine Lab), Roumillat, B. (SCDNR), Sutton, T. (Virginia Institute of Marine Science), Parsons, K. (Virginia Institute of Marine Science), Abel, D. (Coastal Carolina University), and Sancho, G. (College of Charleston)
The sandbar shark, Carcharhinus plumbeus, is a common and economically important species in the western North Atlantic. Additional diet and trophic level information would facilitate the creation of an ecosystem-based management plan. Diet analyses using stomach contents in other regions have revealed an ontogenetic shift in the diet of sandbar sharks in two different areas, but whether this shift takes place throughout their range is unknown. ∆13C and ∆15N stable isotope analysis is a minimally invasive and non-lethal method for determining diet and trophic level. Significant differences in ∆13C signatures were found between young-of-year and juveniles, suggesting that South Carolina sandbar sharks have a similar ontogenetic shift as sandbar sharks in other regions. Differences in total occupied niche area and ∆15N range indicated that young-of-year sharks have more diverse diets than juveniles.
TAXONOMY OF THE BASAL BREGMACEROTIDAE, WITH THE DESCRIPTION OF THREE NEW SPECIES
Simpson, R.G. (GPMB, College of Charleston)
Codlets in the family Bregmacerotidae are small, morphologically unique, gadiform fishes common in the pelagic zone of subtropical and tropical waters worldwide. Despite being common bycatch in midwater fisheries, the taxonomy of the genus has long been poorly understood and several species remain undescribed. This study focuses on a complex of species that has been shown to be phylogenetically basal in the genus. One of them is a very widespread species that is well known, but has long been misidentified as another species. The other two species have only been recorded in the northwestern Indian Ocean. Using meristics, morphometric measurements, external physical characters, and pigmentation pattern, these three undescribed species are diagnosed and described.
WHERE BARNACLES ROAM: THE FATEFUL MEETING OF LARVAE AND DEBILITATED SEA TURTLES
Sloan, K.A. (MES, College of Charleston), Zardus, J.D. (The Citadel), Griffin, D.B. (South Carolina Department of Natural Resources), Boylan, S.M. (SC Aquarium), and Jones, M. (College of Charleston)
Debilitated Turtle Syndrome (DTS) has become a growing concern for sea turtles in South Carolina, and in recent years (2000-2009) has accounted for 10% of the loggerhead (Caretta caretta) strandings in the state. Although the causes of DTS are unknown, loggerheads stranding with DTS are characteristically emaciated, hypoglycemic, anemic, and heavily encrusted with epibiota. The illness is thought to ultimately weaken the turtle to the point that it floats at the water’s surface, restricting the animal to an environment that predisposes it to heavy recruitment of the barnacle Chelonibia testudinaria on the carapace and soft tissue. The time it takes for debilitated loggerheads to manifest this heavy barnacle load is unknown. Our study measured how barnacle growth rate correlates with several environmental factors and experimentally tested whether barnacle recruitment on loggerhead scute varied between debilitated and non-debilitated individuals. Floating arrays holding test panels consisting of four treatments (debilitated turtle scute, non-debilitated turtle scute, Plexiglas, and slate tile) were placed at four independent experimental sites near Charleston, South Carolina. Results from two seasons (2009 and 2010) indicate that the larvae of the turtle barnacle C. testudinaria recruit at significantly higher rates along the open shore and recruit at higher rates to turtle scute as opposed to artificial substrata. Growth rates for this barnacle are also higher in open water but do not vary with substratum type.
COMMUNITY AND TROPHIC STRUCTURE ANALYSIS OF THE SNAPPER GROUPER COMPLEX OFF THE SOUTHEASTERN U.S. ATLANTIC COAST
Stratton, M. (GPMB, College of Charleston), Reichert, M. (SCDNR), Kucklick, J. (NIST), Plante, C. (College of Charleston), and Stephen, J. (SCDNR)
The development of indicators to test the effects of fishing on marine fish communities is imperative to support an ecosystem approach to fisheries management. The indicator average trophic level (TL) has been applied in marine systems worldwide to detect trophic changes in fish communities resulting from human exploitation. Changes in average TL were investigated for an assemblage of reef-associated species in the snapper grouper complex inhabiting continental shelf waters of the southeastern U.S. Atlantic coast. The trophic positions of individual fish from 15 snapper grouper species were estimated from stable isotope ratios of 15N/14N (δ15N) in fish muscle tissue. When compared across a broad size range, 11 of 15 species exhibited significant positive linear relationships (P<0.05) between body weight and δ15N.δ15N values were also positively correlated to body size for all species combined (y=9.02+0.21x; adj.-R2=0.26; F=1401,403; P<0.001), further supporting existing evidence of strong size-based trophic structuring in fish communities. These species-specific linear models were then applied to species-size-abundance data from a snapper grouper fishery-independent survey to detect temporal changes in average TL during 1990-2009. Preliminary time series analysis indicates no change in average TL despite documented changes in biomass and size structure for individual species. Causes for this trophodynamic stasis need investigation but could be due to a combination of effective implemented management measures, poor indicator sensitivity, or trophic redundancy. Further work will include the application of other size-based community indicators and the refinement of stable isotope techniques to describe more precisely the trophic patterns of this fish community.
CAN MAXIMUM OOCYTE DIAMETER (MOD) BE USED AS AN INDICATOR OF REPRODUCTIVE STAGE IN BOTH FRESH AND FROZEN PARALICHTHYS ALBIGUTTA?
Tucker, C. (GPMB, College of Charleston)
During the course of a larger study on flounder spawning off the South Carolina coast, P. albigutta were collected using scuba and spear. Some were fresh collected by South Carolina Department of Natural Resources (SCDNR) divers, and some were frozen fish donated by recreational anglers. Freezing is known to affect the appearance of histological slides made from gonad tissues. The objectives of this analysis were to 1) compare MODs between fresh and frozen tissues of the same reproductive stage and 2) compare MODs among the different reproductive stages. Histological slides of gonad tissues were prepared from 91 fresh and 34 frozen specimens for a larger study on flounder spawning. 2 independent readers staged all slides using criteria based on Wallace and Selman (1981). MOD was measured using Nikon ACT-2U computer software after staging. Results of ANOVA tests with Holmes multiple test correction indicate that MODs from frozen are no different than MODs from fresh for 6 of 7 reproductive stages. Therefore, fresh and frozen tissues were pooled for analysis by stage. Pairwise Wilcoxon tests with Bonferroni corrections found no difference in MODs between the resting and immature stages. There was also no difference between spent and either vitellogenesis or migratory nucleus. MODs were different among all other stages. MOD is an effective tool for staging frozen and fresh tissues, but care must be taken not to confuse freezing damage in vitellogenic or migratory nucleus oocytes for atretsia.
CHARACTERIZATION OF CONNECTIVITY AMONG POPULATIONS OF MEGABALANUS COCCOPOMA ALONG THE SOUTHEASTERN COAST OF THE U.S.
Williamson, T. (GPMB, College of Charleston) and Zardus, J. (Dept. of Biology, The Citadel)
Interest in studies exploring the ecology of invasive species has increased with the concern of how humans are impacting the environment. Modern molecular tools have led to insights into larger ecological questions faced by invasive species as they disperse into novel locations. Megabalanus coccopoma, a Pacific tropical barnacle, arriving along the southeastern coast of the U.S. provides an opportunity to use these tools to characterize connectivity among the different populations. Nuclear and mitochondrial DNA analysis yielded high genetic diversity with low nucleotide diversity though mitochondrial was generally higher than nuclear variation. Limited population structure implies a panmictic population with high dispersal though 13 individuals from Fort Pierce, FL were very highly divergent, suggesting that they recruited from a different source or represent a cryptic species. Several abiotic factors may have influenced the population distributions observed, though limited studies on M. coccopoma would suggest that oceanic temperature plays a major role. Sustained warmer oceanic temperatures during traditionally colder months suggest a means for the stability of a tropical species in areas previously unavailable for habitation. This study provides a baseline for future genetic studies that could clarify the identity of the Fort Pierce individuals and basic ecological research to resolve the influence of abiotic factors on dispersal and recruitment.
KEYNOTE SPEAKER OPENING ADDRESS ABSTRACT:
RHYTHMS IN THE SEA: FROM NEURONS TO NATURE
Watson, Win (Professor of Zoology, University of New Hampshire)
For much of his life Dr. Watson has been fascinated with rhythms. Early in his career he focused on how networks of neurons generated different types of rhythms. More recently, his interest has turned to circadian and circatidal rhythms and the factors that influence when animals express these different patterns of activity. In this talk Dr. Watson will give 4-5 examples of this work, in species ranging from nudibranches to horseshoe crabs. For each example he will describe both the problems they encountered and how they overcame them. One of the overarching themes of the talk will be that experiments never work the first time and it is important to embrace the challenge of solving each and every problem.
KEYNOTE SPEAKER CLOSING ADDRESS ABSTRACT: