Variation of stream dissolved organic carbon quantity, character and ecosystem function in a changing landscape

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One of the most obvious environmental changes caused by humans is the alteration of the landscape. Usually this involves the reduction of forested cover at the expense of agricultural and urban areas. Almost inevitably, these changes in land use affect water quality and quantity in surface and subsurface waters because of altered connections between the land and water. For rivers in these landscapes, modified connections mean that organic matter (generally measured in carbon unites as dissolved organic carbon, DOC) originates primarily from agricultural crops, manure and urban waste instead of natural vegetation, soils and wetlands. This 'modified' DOC can have large implications for the healthy functioning of our rivers. In this project, I will examine how the DOC changes in quality and quantity in river watersheds of contrasting land use from the Great Lakes Basin in South-central Ontario. My research program will further investigate the cause and effect relationships among the physical and biological processes that define river structure and production. I will examine important biological, chemical, and physical factors that change with DOC. I will further test how agriculturally and urban-derived DOC and nutrients affects bacterial growth, food webs and several ecosystem functions such as decomposition, nutrient uptake and the cycling of nitrogen. Finally, I will test for riverine DOC responses to climate change because these might be affected by periods of warm weather and drought. This research will help us understand how human-derived materials (agricultural and residential waste) will affect the health and integrity of aquatic communities.