Spatial variation in trophic structure of nearshore fishes in lake Michigan as it relates to water clarity

Document Type


Publication Date



© 2019, Canadian Science Publishing. All rights reserved. Nearshore water clarity, as measured by remotely sensed K d (490), and stable C and N isotopes of several nearshore fishes differed across the Lake Michigan basin. Values of δ 13 C of round goby (Neogobius melanstomus), yellow perch (Perca flavescens), and spottail shiner (Notropis hudsonis) were depleted in the southeast where water clarity was low relative to the southwest where water clarity was greater. Bayesian analyses were used to evaluate spatial variation in diet composition and quantify the relationship between water clarity and the proportional importance of pelagic energy in fish diets. Water clarity in nearshore areas is likely related to variable riverine inputs, resuspension, and upwelling processes. While these processes may not directly impact δ 13 Corδ 15 N of nearshore fishes, we hypothesize that water clarity differentially affects benthic and pelagic algal production. Lower water clarity in the benthos and subsequently lower benthic productivity may be related to regional diet differences and increased reliance on pelagic energy sources. Mobile fishes such as alewife (Alosa pseudoharengus) may not be in isotopic equilibrium with regional prey sources and depart from spatial patterns observed in other nearshore fishes.

Publication Title

Canadian Journal of Fisheries and Aquatic Sciences