Grant: Discovery Grants Program - Individual

Freshwater ecosystems are biogeochemical hotspots that play an important role in the global carbon cycle especially in relation to their relatively small geographic footprint. The rates at which lakes and rivers respire carbon (“metabolism”) is a key characteristic of these ecosystems. A central piece of the freshwater metabolism puzzle is dissolved organic matter (DOM), due to its very high prevalence and mobility across the landscape (from land to sea). DOM serves as a substrate for microbes, affects the light environment, and controls diverse food web and ecosystem processes in freshwater ecosystems. While DOM quantity has been recognized to be a central determinant of many lake and river properties, it is becoming increasingly clear that not all DOM is chemically equivalent and that its chemical composition (its quality) varies within and among aquatic ecosystems. In this project, I will examine how DOM quantity and quality is affected by nutrients and how, in turn, DOM quality and nutrients regulate ecological function in streams, rivers and lakes. Through a series of field surveys and experiments we will assess sources of DOM, determine pathways of DOM movement and loss, and understand patterns of DOM quality as they relate to nutrients in freshwater ecosystems through time and space. This information on the biogeochemical controls of carbon transformations and fluxes is integral to understanding the effects of global change and land use change on freshwater ecosystems across landscapes. My research team will include at least 15 highly diverse students that I will mentor to complete multidisciplinary research theses that can include principles of ecosystem ecology, water chemistry, biological activity, hydrological transport and mathematics. Finally, their research theses can provide information to management agencies on DOM, its interaction with nutrients, its retention in aquatic systems and its effects on ecological function with significant implications for ecosystem health and ecosystem services (e.g., recreation, drinking water, eutrophication).