Trophic dynamics of several fish species in lakes of a climatically sensitive region, the Hudson Bay Lowlands

Freshwater lakes in the Hudson Bay Lowlands (HBL) area of Ontario are expected to undergo considerable physical, chemical and biological changes related to climatic change; however, the nature of those changes is still very uncertain. As a first step to improve our understanding of fish communities within these subarctic lakes, we aimed to: (a) characterize trophic dynamics of several large-bodied species within three HBL lakes and (b) determine whether trophic dynamics of selected species in the HBL lakes differed from the same species in Southern Ontario lakes. We found that species-specific trophic position and littoral resource reliance varied significantly within and among the HBL lakes of differing biological communities, chemistry and morphometry. Although several significant differences were evident among lakes in the northern and southern regions, we did not find striking consistent differences in trophic dynamics. Based on observations of high variation in trophic position and/or littoral reliance, we can hypothesize that changes in food resources resulting from climatic change would have little impact on most of the large-bodied species.