The effect of off-bottom versus on-bottom oyster culture on total and pathogenic Vibrio spp. abundances in oyster tissue, water and sediment samples.

Varying culture methods are commonly used for eastern oyster, Crassostrea virginica, aquaculture in the Northeast United States. Vibrio vulnificus and V. parahaemolyticus, two human pathogenic bacteria species, accumulate in this edible, filter feeding shellfish. This study examined the use of two methods in an intertidal area (oysters cultured in trays and in bags on sediment) and two methods in a subtidal area (oysters cultured in trays and loose on the sediment) in Massachusetts over the growing season in 2015. Abundance of total V. vulnificus along with total and pathogenic (tdh+/trh+) V. parahaemolyticus were determined in oysters, sediment and water using real-time PCR. Temperature, salinity, turbidity and chlorophyll were continually measured every 15 min at each location. There were significantly higher abundances of total and pathogenic V. parahaemolyticus in on-bottom cultured oysters, while significantly higher abundances of V. vulnificus were identified in oysters from off-bottom culture in a subtidal location in Duxbury Bay, MA. In an intertidal location, Wellfleet Bay, MA, significantly higher abundances of total and tdh+V. parahaemolyticus were found in off-bottom oysters, but significantly higher abundances of V. vulnificus and trh+V. parahaemolyticus were found in on-bottom oysters. Spearman's correlation indicated that temperature is positively associated with concentrations of Vibrio spp. in oysters, water and sediment, but positive correlations between salinity and Vibrio spp. was also observed. Conversely, turbidity had a negative effect on Vibrio spp. concentrations in all sample types. There was no observed relationship inferred between chlorophyll and Vibrio spp. abundances in oysters, water or sediment.

Linking the oceans to public health: current efforts and future directions.

We review the major linkages between the oceans and public health, focusing on exposures and potential health effects due to anthropogenic and natural factors including: harmful algal blooms, microbes, and chemical pollutants in the oceans; consumption of seafood; and flooding events. We summarize briefly the current state of knowledge about public health effects and their economic consequences; and we discuss priorities for future research.We find that:* There are numerous connections between the oceans, human activities, and human health that result in both positive and negative exposures and health effects (risks and benefits); and the study of these connections comprises a new interdisciplinary area, "oceans and human health."* The state of present knowledge about the linkages between oceans and public health varies. Some risks, such as the acute health effects caused by toxins associated with shellfish poisoning and red tide, are relatively well understood. Other risks, such as those posed by chronic exposure to many anthropogenic chemicals, pathogens, and naturally occurring toxins in coastal waters, are less well quantified. Even where there is a good understanding of the mechanism for health effects, good epidemiological data are often lacking. Solid data on economic and social consequences of these linkages are also lacking in most cases.* The design of management measures to address these risks must take into account the complexities of human response to warnings and other guidance, and the economic tradeoffs among different risks and benefits. Future research in oceans and human health to address public health risks associated with marine pathogens and toxins, and with marine dimensions of global change, should include epidemiological, behavioral, and economic components to ensure that resulting management measures incorporate effective economic and risk/benefit tradeoffs.

A model of fishing vessel accident probability.

PROBLEM: Commercial fishing is one of the least safe occupations. METHOD: The researchers develop a fishing vessel accident probability model for fishing areas off the northeastern United States using logit regression and daily data from 1981 to 1993. RESULTS: The results indicate that fishing vessel accident probability declined over the study period. Higher wind speed is associated with greater accident probability. Medium-size vessels have the highest accident probability, while small vessels have the lowest. Within the study region, accident probability is lower in the southwestern section than in the northeastern section. Accidents are likely to occur closer to shore than offshore. Accident probability is lowest in spring. IMPACT ON INDUSTRY: The probability model is an important building block in development and quantitative assessment of management mechanisms related to safety in the commercial fishing industry.