A comparison of PCBs and stable isotopes as ecological tracers of Lake Ontario fishes

Session: Exploring Predator-Prey Relationships and Feeding Ecology in the Great Lakes (3)

Nicole Saavedra, SUNY College of Environmental Science and Forestry, [email protected]
Brian Lantry, U.S.G.S., Lake Ontario Bio Station, [email protected]
Gordon Paterson, Michigan Technological University, [email protected]

Abstract

The stable isotopes of carbon (?¹³C) and nitrogen (?¹⁵N) are among the most commonly applied ecological tracers for delineating habitat and food resource partitioning among coexisting individuals and populations. In comparison, polychlorinated biphenyls (PCBs) are more frequently associated with fish consumption advisories and bioenergetics applications. This study quantified ?¹³C and ?¹⁵N values and PCB congener concentrations for Lake Ontario alewife, rainbow smelt, deepwater sculpin, round goby and lake trout specimens to contrast these dietary tracers and their capacity to distinguish among the general ecologies of these fishes. Stable isotope biplots were consistent with the trophic ecology for these species depicting lake trout as the top predator, benthic characterization of round goby and deepwater sculpin, and pelagic alewives and smelt.  Multivariate analysis of PCBs in prey fishes also discriminated among species but with greater distinction between pelagic alewives and rainbow smelt and benthic gobies and deepwater sculpin having highly unique ordinations relative to other fishes. Further, lake trout PCB profiles demonstrated a degree of resolution among wild and hatchery strains that was not described by stable isotopes. These results indicate that PCBs are highly complementary to stable isotopes as ecological tracers but may provide greater discrimination among species and individuals.