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Emerging infectious diseases in marine systems threaten food security and ecosystem function. Experiments to determine drivers of transmission and mortality from emerging pathogens require a reliable supply of disease-free animals. Imperfect detection of subclinical, latent, and early stage infections, however, necessitates effective treatments to remove infection from animals with unknown infection status. In this study, a procedure utilizing elevated temperatures and over-the-counter parasiticides to remove Hyalophysa lynni was developed. The apostome ciliate H. lynni is responsible for shrimp black gill (sBG) disease in commercially important southeastern shrimp fishery species, including Litopenaeus setiferus (white shrimp). Following a series of pilot studies to determine parasiticides combination and dosage, L. setiferus of unknown infection status were exposed to either 20[degrees]C or 30[degrees]C artificial seawater, and a parasiticide cocktail of metronidazole (3.15 mg [L.sup.-1]) and Cu+2 (0.5 mg [L.sup.-1]) or a medication-free control for 14 days in a fully crossed experimental design. All treatments, except for the 20[degrees]C without medications treatment, significantly reduced pathogen prevalence. The 30[degrees]C artificial seawater with parasiticide treatment resulted in complete curing of the experimental population, but shrimp mortality in this treatment was high (50%). This high mortality may have contributed to the low parasite prevalence found in this treatment by differentially culling infected individuals. If this is the case, the parasiticides may lower the parasite prevalence both by curing infections and heightening stress and subsequent mortality of diseased individuals. Although this procedure was developed to produce H. lynni-free shrimp to facilitate experimental studies of sBG disease, it is likely that this methodology would effectively produce specific-pathogen-free individuals in other crustacean species. KEY WORDS: Litopenaeus setiferus, Crustacea, Hyalophysa lynni, shrimp black gill, disease, parasiticides, gill parasite, apostome ciliate, INTRODUCTION Many marine systems are experiencing emerging infectious diseases that cause significant mortality in commercially and ecologically important species, threatening food security, and ecosystem function (Lafferty et al. 2015, Byers [...]

The white shrimp fisheries in South Carolina and Georgia, USA, have undergone substantial reductions in commercial landings over the past few decades. These declines are associated with reduced commercial effort, shifting climate patterns, and disease outbreaks. For example, recent increases in the occurrence of gill melanization, also known as black gill, have led to the suggestion that this epidemic is a major contributor to reduced shrimp abundance in the region. The goal of this study was to assess long-term patterns and drivers of black gill, and its effects on white shrimp abundance, particularly during the fall, when most of the commercial harvest of white shrimp in this region has historically occurred. Data were compiled for fishery-independent (2002-2017) metrics of white shrimp abundance and black gill prevalence from seven estuaries along the South Carolina and Georgia coasts. Phenology of black gill was variable among years, but mean black gill prevalence was significantly related to the Pacific Decadal Oscillation and El Nino-Southern Oscillation climate indices. These analyses show that the prevalence of black gill is sensitive to large-scale fluctuations in climate patterns. KEY WORDS: shrimp, Penaeus setiferus, fisheries, phenology. Pacific Decadal Oscillation, El Nino-Southern Oscillation, INTRODUCTION Climate warming and coastal development are altering the abiotic nature of estuaries in the southeastern United States (Harley et al. 2006, Osland et al. 2013, Greene et al. 2015). [...]

Fisheries and aquaculture provide food and economic security, especially in the developing world, but both face challenges from infectious disease. Here, we consider management of disease issues from a structured decision‐making perspective to examine how infectious disease can threaten seafood production and influence management decisions. For both wild fisheries and aquaculture, disease‐management objectives generally aim to mitigate the severity and economic burden of outbreaks. General management strategies include manipulating host densities, reducing system connectivity, conserving or improving habitat, and implementing direct treatments or some other biological interventions. To inform decisions, mathematical models can be used to explore disease dynamics and to forecast the potential effectiveness of alternative management actions. Developing and implementing disease‐management strategies also involve considering uncertainties and balancing competing stakeholder interests and risk tolerances. We conclude by outlining several steps for applying structured decision making that are broadly useful to decision makers facing issues related to disease. [ABSTRACT FROM AUTHOR]

Bloom‐forming gelatinous zooplankton occur circumglobally and significantly influence the structure of pelagic marine food webs and biogeochemical cycling through interactions with microbial communities. During bloom conditions especially, gelatinous zooplankton are keystone taxa that help determine the fate of primary production, nutrient remineralization, and carbon export. Using the pelagic tunicate Dolioletta gegenbauri as a model system for gelatinous zooplankton, we carried out a laboratory‐based feeding experiment to investigate the potential ecosystem impacts of doliolid gut microbiomes and microbial communities associated with doliolid faecal pellets and the surrounding seawater. Metabarcoding targeting Bacteria and Archaea 16S rRNA genes/Archaea) and qPCR approaches were used to characterize microbiome assemblages. Comparison between sample types revealed distinct patterns in microbial diversity and biomass that were replicable across experiments. These observations support the hypothesis that through their presence and trophic activity, doliolids influence the structure of pelagic food webs and biogeochemical cycling in subtropical continental shelf systems where tunicate blooms are common. Bacteria associated with starved doliolids (representative of the resident gut microbiome) possessed distinct low‐biomass and low‐diversity microbial assemblages, suggesting that the doliolid microbiome is optimized to support a detrital trophic mode. Bacterial genera Pseudoalteromomas and Shimia were the most abundant potential core microbiome taxa, similar to patterns observed in other marine invertebrates. Exploratory bioinformatic analyses of predicted functional genes suggest that doliolids, via their interactions with bacterial communities, may affect important biogeochemical processes including nitrogen, sulphur, and organic matter cycling. [ABSTRACT FROM AUTHOR]

Severe outbreaks of black gill (BG), heavily melanized gills of crustaceans, have been reported in white (Litopenaeus setiferus) and brown shrimp (Farfantepenaeus azlecus) from coastal Georgia and South Carolina during late summer and fall since the mid-1990s. The cause of this condition is an apostome ciliate that elicits the innate immune response of the shrimp, resulting in the formation of melanized nodules in shrimp gill tissue. In the absence of a definitive identification, the causative ciliate is referred to as the shrimp black gill (sBG) ciliate. During outbreaks, necrosis of gill tissue was often seen in microscopic sections; in some cases, there appeared to be penetration of the ciliate into gill tissue. Shrimp with BG exhibited reduced physical endurance and escape responses compared with shrimp without symptomatic BG. Physical impairment due to BG may contribute to higher predation rates and increased vulnerability to environmental conditions. The infection transmission rate of the sBG ciliate appears to be atypically low for apostome ciliates, raising the question of how epidemic levels of BG reoccur annually. Asymptomatic shrimp placed in direct contact with carcasses (heads) from BG symptomatic shrimp exhibited a significant increase in the development of BG symptoms after 7 days (P = 0.028), but waterborne transmission was not detected. A preliminary survey of sympatric crustacean species, including syntopic species of grass shrimp (Palaemonetes spp.), indicated the possible presence of the sBG ciliate, suggesting that other crustacean species may serve as infection reservoirs. These studies support the conclusion that BG is negatively impacting the penaeid shrimp fishery and highlight the challenges that remain in understanding and managing the ongoing sBG epidemic in the southeastern United States. KEY WORDS: penaeid shrimp, apostome ciliate, black gill, pathology, South Atlantic Bight, INTRODUCTION Penaeid shrimp, including Litopenaeus setiferus (white shrimp) and Farfantepenaeus aztecus (brown shrimp), support one of the most valuable commercial fisheries in the South Atlantic Bight (Gillet 2008), but since [...]

A PCR approach was used to construct a database of nasA genes (called narB genes in cyanobacteria) and to detect the genetic potential for heterotrophic bacterial nitrate utilization in marine environments. A nasA-specific PCR primer set that could be used to selectively amplify the nasA gene from heterotrophic bacteria was designed. Using seawater DNA extracts obtained from microbial communities in the South Atlantic Bight, the Barents Sea, and the North Pacific Gyre, we PCR amplified and sequenced nasA genes. Our results indicate that several groups of heterotrophic bacterial nasA genes are common and widely distributed in oceanic environments.

ABSTRACT Penaeid shrimp including Litopenaeus setiferus (white shrimp), Farfantepenaeus aztecus (brown shrimp), and Farfantepenaeus duorarum (pink shrimp) support one of the most valuable commercial fisheries in the U.S. Southeast Atlantic. [...]

ABSTRACT The eastern oyster Crassostrea virginica once supported one of the largest fisheries in the eastern United States. Oyster populations and the reefs they form have suffered chronic long-term decline [...]

Gorgonians are widespread sub-littoral benthic suspension feeders in the world oceans. However, data on their trophic ecology and role in benthic-pelagic coupling and biogeochemical cycles remain limited. This study assesses the trophic ecology of Leptogorgia virgulata in the Skidaway River estuary, USA (31.9896N, 81.0242W) by analysing carbon and nitrogen isotopic signatures of its soft tissue and different-sized fractions of particulate organic matter (POM) in its environment. Samples were taken in 5 April, 2 August, and 15 October 2012 and 11 January 2013. Results support a distinct temporal shift in the diet of L. virgulata from the POM fraction, Introduction Benthic suspension feeders (BSF) play a key role in population and community ecology of shallow littoral ecosystems because they are abundant and create habitat niches for numerous organisms (Gili [...]

Doliolids are common gelatinous grazers in marine ecosystems around the world and likely influence carbon cycling due to their large population sizes with high growth and excretion rates. Aggregations or blooms of these organisms occur frequently, but they are difficult to measure or predict because doliolids are fragile, under sampled with conventional plankton nets, and can aggregate on fine spatial scales (1–10 m). Moreover, ecological studies typically target a single region or site that does not encompass the range of possible habitats favoring doliolid proliferation. To address these limitations, we combined in situ imaging data from six coastal ecosystems, including the Oregon shelf, northern California, southern California Bight, northern Gulf of Mexico, Straits of Florida, and Mediterranean Sea, to resolve and compare doliolid habitat associations during warm months when environmental gradients are strong and doliolid blooms are frequently documented. Higher ocean temperature was the strongest predictor of elevated doliolid abundances across ecosystems, with additional variance explained by chlorophyll a fluorescence and dissolved oxygen. For marginal seas with a wide range of productivity regimes, the nurse stage tended to comprise a higher proportion of the doliolids when total abundance was low. However, this pattern did not hold in ecosystems with persistent coastal upwelling. The doliolids tended to be most aggregated in oligotrophic systems (Mediterranea and southern California), suggesting that microhabitats within the water column favor proliferation on fine spatial scales. Similar comparative approaches can resolve the realized niche of fast‐reproducing marine animals, thus improving predictions for population‐level responses to changing oceanographic conditions. [ABSTRACT FROM AUTHOR]

Sulfate-reducing bacteria (SRB) and sulfate reduction rates (SRR) are measured in saltmarsh sediments to estimate mercury methylation rates (MMR). Methylmercury production is graphed in relation to the presence of sulfate-reducing bacteria to show a general correlation.

Research has been conducted on the microbial community structure. The technique that allows to extract cells from formalin-preserved salt marsh sediments is discussed.

Research has been conducted on the methymercury production. The quantification of the differences in methylmercury production in pure cultures and in marine sediments to determine the sulfate-reducing bacteria strains is discussed.

Robustness and resilience are widely used in the biological sciences and related disciplines to describe how systems respond to change. Robustness is the ability to tolerate change without adapting or moving to another state. Resilience refers to the ability for a system to sustain a perturbation and maintain critical functions. Robustness and resilience transcend levels of biological organization, though they do not scale directly across levels. We live in an era of novel stressors and unprecedented change, including climate change, emerging environmental contaminants, and changes to the Earth's biogeochemical and hydrological cycles. We envision a common framework for developing models to predict the robustness and resilience of biological functions associated with complex systems that can transcend disciplinary boundaries. Conceptual and quantitative models of robustness and resilience must consider cross-scale interactions of potentially infinite complexity, but it is impossible to capture everything within a single model. Here, we discuss the need to balance accuracy and complexity when designing models, data collection, and downstream analyses to study robustness and resilience. We also consider the difficulties in defining the spatiotemporal domain when studying robustness and resilience as an emergent property of a complex system. We suggest a framework for implementing transdisciplinary research on robustness and resilience of biological systems that draws on participatory stakeholder engagement methods from the fields of conservation and natural resources management. Further, we suggest that a common, simplified model development framework for describing complex biological systems will provide new, broadly relevant educational tools. Efficient interdisciplinary collaboration to accurately develop a model of robustness and resilience would enable rapid, context-specific assessment of complex biological systems with benefits for a broad range of societally relevant problems. [ABSTRACT FROM AUTHOR]

The effects of nutrients, salinity, temperature and the developent and maintenance of competence in the Vibrio strain WJT-1C was studied. Transformation occurred in direct relationship to DNA concentration. Competence was maintained in both spent and nutrient-free media during the experiment. Temperature had no effect on transformation frequency at 15 to 33 degrees Celsius after 20 hours of exposure. The lowest transformation frequencies were observed at salinities of 6 ppt and highest at 22 ppt. Nutrient levels of 1% to 200% had no significant effects on transformation.