Spatio-temporal variation of stable isotope ratios and morphology of Yellow Perch in Saginaw Bay

Session: Poster Session

Taylor Senegal, Purdue University, [email protected]
Timothy Sesterhenn, Purdue University, Forestry and Natural Resources, [email protected]
Charles Roswell, Illinois Natural History Survey, [email protected]
Steve Pothoven, NOAA-GLERL, [email protected]
Tomas Hook, Purdue University, Dept. Forestry and Natural Resources, [email protected]

Abstract

Saginaw Bay, Lake Huron, is a meso- to eutrophic ecosystem that supports commercial and recreational Yellow Perch Perca flavescens fisheries. Concerns over limited recruitment success prompted research of spatio-temporal variation in age-0 Yellow Perch trophic interaction. Spatial variation in stomach content composition was evident among individuals across sites, independent of annual differences in prey availability and ontogenetic diet shifts. To investigate if these differences in short-term diet indicators are reflective of long-term indicators, we quantified stable isotope ratios and morphology of Yellow Perch. Specifically, soft tissue samples were analyzed for carbon (?¹³C) and nitrogen (?¹⁵N) isotope ratios, which reflect recent diet and habitat use. Further, 18 landmarks were used to quantify the morphology of individual Yellow Perch. ?¹³C values varied by year, while ?¹⁵N values depleted as distance from the Saginaw River increased. Enriched ?¹³C values, often indicative of benthivory, are consistent with annual variation in the relative availability of benthic macroinvertebrates and pelagic zooplankton.