Grant: Discovery Grants Program - Individual

The objective of my research program is to improve our understanding of the role of submersed aquatic vegetation (SAV) in freshwater systems at the whitin-lake level by taking a landscape perspective, with a particular focus on the effects of habitat fragmentation (i.e. the process leading to the division of continuous habitat into smaller and isolated patches) on aquatic communities. SAV is crucial in maintaining both high invertebrate diversity and zooplankton grazing potential by reducing fish predation pressure and exposure to ultraviolet radiation of aquatic organisms. Moreover, despite the importance of SAV landscapes (i.e. spatially heterogeneous areas of the lake floor composed of various discrete SAV patches) in maintaining both high biodiversity and ecosystem services, such as water quality, in shallow lakes, virtually nothing is known about the consequences of the fragmentation of this key habitat. During the next five years, my students and I will use an in situ experimental approach to analyze the effects of SAV habitat complexity on aquatic communities at different scales. More specifically, we will analyze the relationship between habitat complexity and both invertebrates abundance and diversity from the patch to the SAV landscape scale. The proposed research will be conducted in lakes with rising management problems due to invasive SAV where a compromise is needed between the demand to reduce SAV for recreational purposes and the need to maintain good water quality. The long-term objective of my research program is to understand how the ecological services (e.g. maintain of high zooplankton grazing potential) offered by SAV are affected by habitat fragmentation. To reach this objective, we will use manipulated lakes, where the fragmentation of SAV habitat will be increased experimentally by covering portions of lake bottom with biodegradable geotextiles. The presence of invasive SAV in the study lakes will allow the experimental manipulation of the degree of habitat fragmentation at the whole-level. In such systems SAV are in fact often seen as weeds and managed through practices such as harvesting to facilitate recreative activities. The manipulation of SAV landscapes in a controlled and hypothesis-oriented manner is one of the novelties of the proposed research. Another novelty of this program lies in the coupling of direct measures of invertebrate community structure with state-of-the-art estimates of habitat complexity to quantify the structure of SAV beds at different spatial scales. Whereas this approach is common in landscape ecology studies, it has only rarely been adopted by aquatic ecologist. Whereas the fundamental goal of this research program is to analyze how biotic interactions in lake food chains can be affected by habitat fragmentation, our ultimate goal is to understand how we can use this knowledge to restore ecological functions in shallow lakes.