Elemental ecology: Ecological stoichiometry, limiting nutrients, and lake foodwebs

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Nutrient imbalances between aquatic consumers and their food can strongly affect ecological interactions in lake food webs and ecosystem processes. For example, low phosphorus content in algae reduces growth and reproductive rates of lake zooplankton. As many Canadian lakes are characterized by low (if not extremely low) nutrient inputs, nutritional constraints may be especially common and underappreciated in their effects on the structure and function of our lake ecosystems. Despite their possible importance, there remains uncertainty regarding nutrient imbalances- about which elements are most limiting, how this limitation affects invertebrates and their food, and how this affects carbon storage in lakes. This program will study the effects of nutrients in aquatic ecosystems using a combination of laboratory and field based approaches. In particular, we will characterize patterns of nutrient content in lake food webs, document animal and food responses to changes in nutrient availability, and measure rates of decomposition in organic matter exposed to different nutrient concentrations. By doing so, we will address novel ecological questions about why nutrient imbalances develop and what their consequences are for aquatic communities. In addition, this work will help develop new methods of tracking nutritional stress in aquatic organisms and connecting their nutritional requirements to ecological dynamics. Altogether, this work will deepen our understanding of how nutrients affect lake food webs, which is necessary to better mitigate and manage effects of human nutrient pollution.