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

摘要: Nitrogen loading from anthropogenic sources, including fertilizer, manure, and sewage effluents, has been linked with declining water quality in coastal lagoons worldwide. Freshwater inputs to mid-Atlantic of the USA are terrestrially influenced sources: groundwater overland flow via streams agricultural ditches, occasional precipitation events. Stable nitrogen isotopes ratios (δ15N) bioindicator species combined conventional monitoring were used assess sources provide insights into their origins. Water data revealed that nutrients derived terrestrial increased after Tissues two species, a macroalgae (Gracilaria sp.) eastern oyster (Crassostrea virginica) analyzed for δ15N determine spatial temporal patterns sources. A broad-scale survey assessment deployed (June 2004) detected regions elevated δ15N. Macroalgal (7.33 ± 1.15‰ May 2006 6.76 ± 1.15‰ July 2006) responded quickly sustained June nutrient pulse, but did not detect at fine scale. Oyster (8.51 ± 0.89‰) slowly over longer time periods exhibited slight gradient finer Overall, values oysters infer human animal wastes important some areas Maryland’s bays. Different integration across multiple organisms may be indicate various scales, which will help focus management.