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Nitrogen Isotope Ratios of Juvenile Winter Flounder as an Indicator of Anthropogenic Nitrogen Inputs to Estuarine Systems
Citation:
Pruell, R. AND B. Taplin. Nitrogen Isotope Ratios of Juvenile Winter Flounder as an Indicator of Anthropogenic Nitrogen Inputs to Estuarine Systems. Presented at Ocean Sciences Biennial Meeting, Honolulu, HI, February 23 - 28, 2014.
Impact/Purpose:
The purpose of this research is to evaluate the use of fish tissue isotope ratio as a tool to monitor anthropogenic nitrogen inputs to aquatic systems. This may help track trends in nitroge inputs.
Description:
Nitrogen isotope ratios (15N) were measured in muscle tissue of juvenile winter flounder, Pseudopleuronectes americanus, collected from several estuarine systems (lagoons, river, bay) along the coast of Rhode Island, USA over a three-year period. Significant differences in 15N were observed among estuarine systems; fish from the coastal lagoons had the lowest 15N values followed by those from an estuarine river and then Narragansett Bay. This trend was the same over the three years and is consistent with several indicators of anthropogenic influence such as population density and known nutrient sources. Within Narragansett Bay some unexpected trends in 15N were observed. Flounder from stations in the lower Bay had depleted 15N values as expected. However, fish from the other Bay stations along a nutrient gradient were not different from each other except for the station furthest north in the estuary which was lower. Depleted 15N values at this nutrient-rich station may indicate that concentration dependant fractionation should be considered when using nitrogen isotope ratios in biota to infer the relative influence of anthropogenic nitrogen inputs among locations.