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Use of Stable Isotopes in Benthic Organic Material as a Baseline for Estimating Fish Tropic Positions in Lakes
Citation:
Lake, James L., J. Serbst, A. Kuhn, N. Smucker, P. Edwards, A. Libby, M. Charpentier, AND K. Miller. Use of Stable Isotopes in Benthic Organic Material as a Baseline for Estimating Fish Tropic Positions in Lakes. CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES. NRC Research Press, Ottawa, Canada, 76(7):1227-1237, (2019). https://doi.org/10.1139/cjfas-2017-0381
Impact/Purpose:
In small lakes in New England, isotope ratios of nitrogen and carbon in organic material isolated from surface sediments were tested for use in assessing human impacts from watershed development and for determining the relative food web position of fish and other aquatic organisms. Strong relationships were found showing increased human development was associated with increased nitrogen isotopic concentrations. Comparisons of the nitrogen isotopic ratio between surface sediment and largemouth bass, the top level predator, showed constant relationships indicating the sediment measurement was useful for assessing food web positions. Overall, the collection and analysis of carbon and nitrogen isotopes in surface sediment showed great promise as a simple method to assess human impact and for quantifying food web structure at lakes. Because of its simplicity, the procedure is particularly applicable to studies where data from large numbers of lakes are required.
Description:
Stable isotope ratios in benthic organic material (BOM) isolated from lake surface sediments were useful for assessing human impacts in watersheds and as baselines for estimating trophic positions (TP) of largemouth bass (LB) (Micropterus salmoides), a dominant apex predator. Ratios of BOM δ15N were strongly correlated with water chemistry and land cover associated with anthropogenic development in 51 watersheds located in Rhode Island, USA. Ratios of BOM δ15N and δ13C were significantly correlated with those in LB, indicating a strong linkage between BOM and food webs across sites; however, BOM δ13C was less effective than δ15N in estimating TP of LB. Regressions of δ15N in LB vs a δ15N in BOM baseline were less precise (R2 = 0.78) than those estimated from other baselines, for example, mussels (R2 = 0.91). However, BOM has the distinct advantages of being readily available, easily sampled, and represents changes in baseline δ15N ratios of aquatic biota from anthropogenic development. These qualities make BOM δ15N ratios particularly useful for studying the dynamics of stable isotope ratios in large numbers of lakes.
URLs/Downloads:
DOI: Use of Stable Isotopes in Benthic Organic Material as a Baseline for Estimating Fish Tropic Positions in Lakes