Author: Katherine E O'Reilly,  PhD Candidate (University of Notre Dame)

Description:
In the Laurentian Great Lakes, fish movement between productive coastal wetland and adjacent open-water nearshore habitats represents an understudied but potentially important linkage supporting lake fisheries production. We hypothesized that yellow perch (Perca flavescens) transport wetland-derived productivity to nearshore food webs, but that role can change with ontogenetic shifts in diet and habitat use. We also predicted that the relative strength of fish-mediated habitat linkages would vary depending on hydrologic connectedness of the wetland to the nearshore. We collected perch and potential food sources from nine paired coastal wetland-nearshore sites across Lake Michigan representing common geomorphologies and quantified resource use with Bayesian stable isotope mixing models. Juvenile perch collected from wetlands consumed a smaller proportion of nearshore resources than did more mobile adults from the same wetland. The least hydrologically connected sites had low cross-habitat resource use (e.g., wetland perch consumed small proportions of nearshore resources and vice versa), while sites with greater levels of hydrological connectivity had substantial cross-habitat resource use. When combined with complementary approaches such as otolith chemistry that provide insight into habitat use, stable isotope mixing models can increase our understanding of habitat linkages in large lakes. The results presented here will contribute to more comprehensive lake-wide food web models and provide managers with information to prioritize locations for conservation and restoration.

Category: Scientific Program Abstract > Special Session > SS10 Physical, chemical and biological connections in large lake ecosystems