Cumulative Impacts of Residential Lakeshore Development on Littoral Habitat

The littoral zone contains the majority of vegetation within the lake ecosystem and is critical to the physical and biological integrity of lentic water bodies. Aquatic macrophytes stabilize the shoreline and support macroinvertebrate and fish communities by providing spawning substrate, feeding area, and refuge. In-water structures such as docks, piers, and other alterations associated with shoreline residential development have been shown to decrease aquatic vegetation and coarse woody structure (CWS). As the extent of lakeshore development increases, understanding the consequences of site- and lake-level alterations is necessary to better guide management decisions. We investigated the effects of development on near-shore habitat across 30 northern Minnesota lakes, respectively. The lakes are of similar size, class, and geology and represent a range of shoreline development.  Results from the first of two field seasons reveal a negative trend in CWS density as lakeshore dock-density increases. Significantly more CWS was found at natural sites compared with developed sites. Biovolume of emergent macrophytes is significantly higher along natural than developed shorelines. Fieldwork will conclude after the summer of 2012 and this research will be incorporated into a framework to assist lake managers in the implementation of sustainable near-shore development.