Spatio-temporal variation of round goby diets fatty acids, and tissue δ13C and δ15N in near-shore Lake Michigan, 2010 and 2011 [presentation]

Invasive species have dramatically restructured the Lake Michigan ecosystem over the past 100 years and will likely continue to disrupt this system well into the future. Understanding 1162013trophic roles of non-native species is key to elucidating potential impacts of current and potential future invaders. Round goby were first detected in Lake Michigan in 1994, and have since increased dramatically in abundance. While past studies of round goby in Lake Michigan have primarily focused on specific regions and habitats, Lake Michigan is a large,diverse system and round goby trophic interactions may vary across regions and over time. During 2010 and 2011, we collected round goby and their potential prey at ten sites throughout Lake Michigan. At each site, we collected gobies during May, July, andSeptember at three depths (3m, 7-9m, and 14-16m) via 2-hr bottom set, micromesh gillnets. In the laboratory, we identified and enumerated diet contents and potential benthic prey items, and homogenized gobies for subsequent fatty acid and δ13C and δ15N stable isotope quantification. Preliminary results indicate diets, fatty acids, and stable isotopes ratios of gobies vary individually (by size), seasonally, and spatially (rock v. sand substrate; east v. west Lake Michigan).