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Cultural Eutrophication Is Reflected in the Stable Isotopic Composition of the Eastern Mudsnail, Nassarius obsoletus
Author(s) -
Watson Elizabeth Burke,
Szura Katelyn,
Powell Elisabeth,
Maher Nicole,
Wigand Cathleen
Publication year - 2018
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2017.05.0214
Subject(s) - eutrophication , environmental science , estuary , isotopic signature , trophic level , ecology , dominance (genetics) , isotope analysis , population , biota , water quality , stable isotope ratio , oceanography , nutrient , biology , geology , biochemistry , physics , demography , quantum mechanics , sociology , gene
In aquatic ecosystems, biological indicators are used in concert with nutrient concentration data to identify habitat impairments related to cultural eutrophication. This approach has been less commonly implemented in coastal areas due to the dominance of physical conditions in structuring biological assemblage data. Here, we describe the use of the stable isotopic composition of Nassarius obsoletus (Say), the eastern mudsnail, as an indicator of cultural eutrophication for 40 locations in coastal estuaries in New York. We found 15 N enrichment in mudsnail tissue where watersheds had high population densities, land use patterns were more urbanized, and when sampling sites were adjacent to wastewater treatment plant discharges. Stable carbon isotopes were responsive to salinity and watershed forest cover, with more saline sites reflecting a predominantly C 4 or algal carbon isotopic signature and more forested sites a lighter isotopic signature reflecting greater inputs of C 3 terrestrial detrital carbon. Mudsnail nitrogen isotopic composition had a high level of separation between more affected and pristine watersheds (from 6.6 to 14.1‰), highlighting its utility as an indicator. We thus propose that stable isotope values of estuarine biota, such as the eastern mudsnail, can be used in concert with water quality data to identify areas where improvements in water quality are needed and can also be used to identify sources of detrital carbon to estuarine environments. Core Ideas We analyzed Nassarius obsoletus tissue and shell for δ 15 N and δ 13 C. δ 15 N values strongly reflected anthropogenic trophic enrichment from wastewater. δ 13 C values reflected C4 vs. C3 plant signatures on the basis of salinity and forest cover. Stable isotope signatures of estuarine biota are useful indicators of water quality.