Terrestrial inputs to aquatic ecosystems: effects on food webs and carbon cycling

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My research program seeks to understand how cross-habitat connections influence food webs and ecosystem carbon cycles in lakes. Lakes receive substantial inputs of terrestrial organic matter from their watersheds. These inputs are consumed by aquatic organisms, helping to fuel production of fishes and invertebrates, and driving many lakes to be net sources of carbon to the atmosphere. Ongoing environmental changes are expected to alter terrestrial inputs to lakes, but the implications of these changes for food webs, fish populations, and carbon cycling are unclear. Over the next five years I will focus on two primary objectives to address those unknowns. First, I will use a whole-lake experiment, cross-lake comparative studies, and food web models to determine whether and when terrestrial inputs serve to subsidize or subtract from production of fishes and other consumers in lake food webs. Second, I will develop an improved model of land-lake-atmosphere carbon cycling, and apply this model to understanding carbon fluxes in temperate and boreal lakes. Collectively, these studies will test key predictions of ecological subsidy theory, elucidate the resources that support fish populations in lakes, and refine our understanding of the role of lakes in regional carbon cycles in lake-rich landscapes such as Canada.