Oyster and Macroalgae Bioindicators Detect Elevated δ15N in Maryland’s Coastal Bays

Anthropogenic sources of nitrogen have been linked to declining coastal water quality worldwide. A paper in the July 2009 issue of Estuaries and Coasts reports that elevated stable nitrogen isotopes ratios (δ15N) in two bioindicator species, "a macroalgae (Gracilaria sp.) and the eastern oyster (Crassostrea virginica) were used to infer that human and animal wastes were important nitrogen sources in some areas of Maryland’s coastal bays. Different nitrogen integration periods across multiple organisms may be used to indicate nitrogen sources at various spatial and temporal scales, which will help focus nutrient management."