No abstract

Persistent organic pollutants (POPs) in biota are influenced by ecological, physiological, and physicochemical properties; however, there is a need for a better understanding about the interplay of these parameters on POP dynamics and fate. To address this, POPs in three Lake Erie freshwater fishes (freshwater drum, Aplodinotus grunniens; walleye, Sander vitreus; and white perch, Morone americana) with different feeding ecologies were assessed using life history characteristics and three stable isotopes (δ 13 C, δ 15 N, and δ 34 S). Lipid normalized POP concentrations were in the range of past studies and were generally similar among the three species when all ages were combined. Principal component analysis (PCA) found the two significant PCs (explaining 59% and 10% of the variation), with all POPs loading significantly onto PC1, which indicated a common source of contamination, likely legacy sediment loads. Loadings on both PCs were correlated with POP log K OW . Age, habitat use (δ 13 C and δ 34 S), trophic position (δ 15 N) and interactions between age and δ 15 N, age and species, and δ 15 N and δ 34 S were significant predictors of POP concentration based on PC1 scores, whereas δ 13 C and species were significant predictors of PC2 scores. The similar concentrations among the species, yet variation related to the ecology (age and trophic position) across individuals demonstrates the complexity of contaminant dynamics in freshwater fish in a large lake system and the need to consider variation across individuals within species.

1. It is essential to establish a baseline in studies using stable isotopes to interpret trophic relationships across ecosystems and through time. Studies in freshwater ecosystems struggle to quantify baseline stable isotopes due to difficulties collecting representative samples, particularly from pelagic habitats. We assessed temporal and spatial variation in δ 13 C, δ 15 N, and δ 34 S in a commonly used pelagic baseline, seston (n = 156), in Lake Erie to understand mechanisms that correlate with baseline stable isotope dynamics in large lakes. Seston contains a wide range of material which can confound stable isotope interpretation, and we examined the utility of element content and ratios to account for variation in sample source.2. Seston was collected in each of the three basins of Lake Erie from May to October in 2017-2019 at nearshore (<10 m depth) and offshore (>10 m depth) sites.General linear models were conducted on each stable isotope (δ 15 N, δ 13 C, and δ 34 S) and sample composition (variables: %N, %C, %S, C:N, C:S, and N:S) to assess how basin, month, and collection year influenced seston stable isotopes and composition.