Environmental Change in Great Lakes Coastal Ecosystems

My dissertation evaluated the function and structure of large lake coastal ecosystems, which consist of coastal wetlands, shallow pelagic habitats, and tributaries, with a focus on evaluating ecological functioning and services in light of human-caused environmental change. Although much of this research took place in Lake Michigan, my dissertation has broad relevance to the Laurentian Great Lakes and large lakes globally because coastal ecosystems are particularly vulnerable to anthropogenic stressors due to their transitional location on the landscape. My dissertation demonstrated that coastal ecosystem function and structure is influenced by a variety of intrinsic (e.g., geomorphology) and extrinsic factors (e.g., terrestrial and lake disturbances). By combining observational and modeling approaches, I identified important processes underpinning energy flow through coastal ecosystem food webs that support valuable ecosystem services such as nearshore fisheries production. First, I demonstrate that resource use by yellow perch (Perca flavescens) across a complex mosaic of coastal habitats in Lake Michigan contributes to energy fluxes supporting nearshore fisheries production, a process I describe as “lakescape connectivity.” I then compare coastal wetland food web structure using stable isotope metrics to show that properties such as fish predator trophic position and community trophic redundancy are influenced by regional and site-level variation in intrinsic characteristics such as extent of connectivity with the adjacent lake and extrinsic characteristics including level of disturbance. I then investigate differences in heavy metal accumulation between two sportfish species that use coastal ecosystems (Chinook salmon, Oncorhynchus tshawytscha, and walleye, Sander vitreus) and assess if otolith (ear stone) microchemistry can complement traditional contaminant monitoring approaches (i.e., using muscle tissue). I then broaden the scope of my dissertation by applying information from risk management of nonindigenous species introductions in the Laurentian Great Lakes to create an accurate risk assessment tool for the large lakes of the East African Rift Valley. Finally, I use social media to develop an online model for effectively communicating with diverse audiences about complex ecological challenges facing large lakes, such as the loss of freshwater fish biodiversity. Overall, my dissertation provides strong evidence in support of management approaches that integrate linkages connecting the complex mosaic of coastal habitats, i.e., managing to maintain “lakescape connectivity.” Effective management of large lake coastal ecosystems in the Anthropocene will require interdisciplinary approaches that bring together diverse disciplines (e.g., biology, chemistry, economics, sociology) and stakeholder groups to preserve ecosystem functioning and services in light of environmental change.