The impacts of ontogenetic dietary shifts in yellow perch (Perca flavescens) on Zn and Hg accumulation.

Abstract Yellow perch ( Perca flavescens ) undergo several ontogenetic dietary shifts, and consequently these fish feed at different trophic levels and rely on different carbon sources over their lifetime. Stable isotope ratios of nitrogen ( δ 15 N) and carbon ( δ 13 C) are powerful ecological tools that are used to provide a temporally integrated description of the feeding ecology of aquatic animals such as fish. The main objective of this study was to use stable isotopes of nitrogen and carbon to determine if dietary changes affected mercury (Hg) and zinc (Zn) accumulation in yellow perch ranging in size from approximately 5 cm to 27 cm. Results showed that Hg bioaccumulation generally increased with increasing trophic level in fish feeding at higher trophic levels, however, the relationship between Hg levels and δ 15 N was non-linear showing no relationship in small fish (less than 15 cm). In contrast, there was a negative, linear relationship between δ 15 N and Zn, suggesting that as perch fed at progressively higher trophic levels, less of Zn bioaccumulated. No relationship was observed between δ 13 C and metal levels in perch. Collectively, these results demonstrate a contrast in the behavior of Zn and Hg bioaccumulation in yellow perch as a function of trophic status.