Bacterial community profiles andVibrio parahaemolyticusabundance in individual oysters and their association with estuarine ecology

ABSTRACTOysters naturally harbor the human gastric pathogenVibrio parahaemolyticus, but the nature of this association is unknown. Because microbial interactions could influence the accumulation ofV. parahaemolyticusin oysters, we investigated the composition of the microbiome in water and oysters at two ecologically unique sites in the Great Bay Estuary, New Hampshire using 16s rRNA profiling. We then evaluated correlations between bacteria inhabiting the oyster withV. parahaemolyticusabundance quantified using a most probable number (MPN) analysis. Even though oysters filter-feed, their microbiomes were not a direct snapshot of the bacterial community in overlaying water, suggesting they selectively accumulate some bacterial phyla. The microbiome of individual oysters harvested more centrally in the bay were relatively more similar to each other and had fewer unique phylotypes, but overall more taxonomic and metabolic diversity, than the microbiomes from tributary-harvested oysters that were individually more variable with lower taxonomic and metabolic diversity. Oysters harvested from the same location varied inV. parahaemolyticusabundance, with the highest abundance oysters collected from one location. This study, which to our knowledge is the first of its kind to evaluate associations ofV. parahaemolyticusabundance with members of individual oyster microbiomes, implies that sufficient sampling and depth of sequencing may reveal microbiome members that could impactV. parahaemolyticusabundance.

Impacts from ditching salt marshes in the mid-Atlantic and northeastern United States

Tidal inundation extent and duration, and water drainage and retention by marsh peat — marsh hydrology — determine most physical and ecological characteristics of salt marsh systems. Ditching, installed across nearly all marshes on the US east coast by 1940 to control mosquitoes, alters marsh hydrology. Two linchpin papers are used here as springboards to review the literature that describes the resulting effects, which clearly include reduced water table height for most marshes and changes in avian populations. Effects on invertebrate populations, including mosquitoes, are generally less, although to a smaller degree than is sometimes reported. Impacts on nekton are not clear, although probably negative. Tidal range and the degree of tide asymmetry appear to have greater effects on intermarsh variations in effects from ditching than has generally been appreciated or studied. Overall, although changed patterns of nutrient releases and promotion of Phragmites australis invasions are important ecological effects extending beyond individual sites, and salt marsh aesthetics are marred, ditching impacts are less than certain other anthropogenic alterations of coastal processes that affect salt marshes and estuarine ecology to a much greater extent.