On Climate and the Dynamic Structure of Boreal Lake Food Webs

Despite widespread interest in the incidence of climate driven biodiversity changes, research only recently attempts to use theory to predict and then empirically test climate influences on the macroscopic properties of nature’s food webs. Given that climate alters lake thermal structure, we hypothesize that climate driven thermal constraints on organisms (like cold water fish) alter accessibility across lake pelagic and littoral compartments thus changing predator habitat coupling, omnivory and trophic position. We use stable isotopes to document food web structure in boreal lakes with lake trout (Salvelinus namaycush) sampled across a range in climate. A preliminary analysis suggests that the contribution of littoral derived carbon to lake trout is reduced in relatively warmer climates. We argue that these types of changes modify the built-in responsive capacity of lake ecosystems. We end by further discussing the implications of climate warming for the persistence of lake ecosystems, and our continued use of their valuable resources.