Exploring yellow perch diets in Lake Michigan through stomach content, fatty acids, and stable isotope ratios Austin Happel a, ⁎, Sara Creque a , Jacques Rinchard b , Tomas Höök c , Harvey Bootsma d , John Janssen d , David Jude e , Sergiusz Czesny a a Lake Michigan Biological Station, Illinois Natural History Survey, University of Illinois, Zion, IL, USA b Department of Environmental Science and Biology, The College at Brockport-State University of New York, Brockport, NY, USA c Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA d School of Freshwater Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA e School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI, USA abstract article info Article history: Received 28 May 2014 Accepted 19 January 2015 Available online xxxx Communicated by David Bunnell Index words: Fatty acid profiles Stable isotope ratios Yellow perch Lake Michigan Diet composition Describing food web structure through either direct or indirect diet analysis is often a fundamental step in elucidat- ing ecosystem dynamics and developing resource management goals. The present study examines spatial trophic connections in an opportunistic forager, juvenile yellow perch (Perca flavescens), through the concomitant use of stomach content, fatty acid profiles, and stable isotope ratio methods. During September 2010, yellow perch were collected at nine coastal locations representative of Lake Michigan's habitat heterogeneity. The three diet assessment methods revealed differential levels of spatial diet heterogeneity. In general, yellow perch relied on pelagic prey more along the eastern shoreline, and over rocky substrates within each shoreline grouping. Converse- ly, high benthivory was noted in yellow perch from sandy substrates and western locations. Intra-population spatial diet dissimilarity may be common yet over looked among other species within large systems. We further advocate the concurrent examination of chemical ecological tracers (e.g., stable isotopes and fatty acid profiles) and stomach contents to investigate diet patterns of predators. © 2015 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Introduction Traditionally, investigation of stomach contents has provided ecologists with diet characterizations and facilitated evaluation of phenomenon such as prey resource overlap (Creque and Czesny, 2012), ontogenetic diet shifts (Roswell et al., 2013) and effects of man- agement actions (Lotze et al., 2006). However, variability in stomach contents due to factors such as short-term feeding irregularities and differential digestion rates associated with prey type (Macdonald et al., 1982) or ambient conditions (e.g., temperature; Legler et al., 2010) sup- ports the use of more time-integrated dietary assessment methods. To this end, contemporary diet studies have employed indirect methodolo- gies, utilizing biomarkers that accumulate in a predictive way, paired with stomach content data to provide both long- and short-term foraging information (i.e., Vinson and Budy, 2011). Fatty acid profiles of consumers' tissues have been used as qualitative descriptors of consumption patterns (Iverson, 2009; Czesny et al., 2011). Long chain fatty acids are stored in predator tissues in patterns reflective of prey consumed over 4–12 weeks (Kirsch et al., 1998; Budge et al., 2011). For example, palmitoleic acid (16:1n-7), α-linolenic acid (18:3n-3), and eicosapentaenoic acid (20:5n-3) are associated with diatoms, detritus, and bacteria (i.e., benthic zone), while elevated levels of docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) are found in non-diatom phytoplankton (esp. flagellates) and their zoo- plankton predators (i.e., pelagic zone) (Bell et al., 1994; Napolitano, 1999; Brett et al., 2009; Kelly and Scheibling, 2012). While generally considered a diatom tracer, high concentrations of 16:1n-7 have been found in chironomids and benthic feeding freshwater fishes (Bell et al., 1994; Czesny et al., 2011; Kelly and Scheibling, 2012). Thus, 16:1n-7 qualitatively tracks association with benthic areas, and 22:6n-3 with zooplankton and pelagic areas (Ahlgren et al., 1997; Czesny et al., 2011; Kelly and Scheibling, 2012). Similarly, carbon stable isotope δ 13 C values provide qualitative assessments of relative pelagic vs. benthic sources of primarily productivity (Fry, 2006). Nitrogen stable isotope δ 15 N values enrich (i.e., increase) through trophic transfer, allowing relative trophic positions to be inferred (France, 1995). Concomitant use of multiple techniques to describe trophic linkages may offer stronger insights than those gained from each method alone. Lake Michigan's fish community has a history of anthropogenic mediated alterations (e.g., commercial fishing, phosphorus loadings, Journal of Great Lakes Research Supplement xxx (2015) xxx–xxx ⁎ Corresponding author. E-mail addresses: Happel2@illinois.edu (A. Happel), Screque@illinois.edu (S. Creque), Jrinchar@brockport.edu (J. Rinchard), Thook@purdue.edu (T. Höök), Hbootsma@uwm.edu (H. Bootsma), Jjanssen@uwm.edu (J. Janssen), Djude@umich.edu (D. Jude), Czesny@illinois.edu (S. Czesny). JGLR-00887; No. of pages: 7; 4C: http://dx.doi.org/10.1016/j.jglr.2015.03.025 0380-1330/© 2015 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Great Lakes Research journal homepage: www.elsevier.com/locate/jglr Please cite this article as: Happel, A., et al., Exploring yellow perch diets in Lake Michigan through stomach content, fatty acids, and stable isotope ratios, J. Great Lakes Res. (2015), http://dx.doi.org/10.1016/j.jglr.2015.03.025