Spatial variability of the stable isotope (δ 15N) composition in two freshwater bivalves (Corbicula fluminea and Elliptio complanata)

We compared the isotopic composition in freshwater bivalves (Corbicula fluminea and Elliptio complanata) from streams with different nitrate concentrations in a North Carolina river basin. Nitrogen isotopic (δ 15N) tissue values of C. fluminea and E. complanata were significantly higher in an agricultural land-use stream site compared to urban and forested samples (p < 0.05). Nitrogen (δ 15N) tissue values for both species were significantly (p < 0.001) associated with land-use type or patterns. The potential use of resident, non-native bivalves as biomonitors of potentially harmful nitrogen levels was implied.