Nitrogen Source Tracking and Benthic Community Assessment in Relation to Oyster Aquaculture in the Delaware Inland Bays
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The Delaware Inland Bays consist of three shallow bays located in southern Delaware. These bays are surrounded by highly developed areas and have low flushing rates, leading to anthropogenic activities resulting in water quality degradation. This results in loss of biodiversity and abundance of organisms within the bays. The ongoing degradation of the bays since the late 1800’s has led to a dramatic decline in local Crassostrea virginica populations. Oysters are keystone species, which provide habitats for organisms, help to improve water quality and act as bioindicator for the ecosystem health. The goals of this research are two fold: i) determine the sources of nitrogen pollution in the bays using oysters as a bioindicator and ii) identify if the introduction of oyster aquaculture improves local biodiversity and abundance of macrobenthos. To achieve these goals, field study was conducted in Rehoboth, Indian River, and Little Assawoman Bays. Aquaculture gear was placed at one location in each bay. Stable isotope ratios of nitrogen of oyster tissue, water sample and soil samples were analyzed to identify the sources of pollution and to assess the health of the bays. A benthic community assessment of Polychaetes was used to identify the impacts of oyster aquaculture. The results of the stable isotope analysis indicate Indian River Bay has the highest levels of anthropogenic nitrogen loading. The results of the benthic community assessment indicate that there was no significant impact to Polychaete abundance or species richness from the oysters and aquaculture gear. Little Assawoman bay did have significantly higher abundance and species richness than the other bays. This research is expected to help better understand the role of oyster aquaculture restoring the viability in natural habitat of the Delaware Inland Bays.