Effects of residential shoreline development on near shore aquatic habitat in Minnesota lakes

Abstract

The littoral zone contains all of the vegetation within a lake 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 from predators. Riparian 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 shoreline alterations is necessary to better guide management decisions. The intensity and type of alterations may be an important factor regarding the extent of effects on littoral habitat. We investigated site-scale effects of lakeshore development on near-shore habitat across 10 northern Minnesota lakes using the Minnesota Department of Natural Resource's Score Your Shore (SYS) survey, to assess development intensity. We also examined lake-wide effects of development density. Study lakes were of similar size, class, and geology and represented a range of shoreline development. Developed sites had significantly lower macrophyte species richness than undeveloped sites. Emergent and floating-leaf macrophyte biovolume was also lower at developed sites. Coarse woody structure (CWS) density was lower at developed sites than undeveloped sites. SYS score was a significant factor in models of most macrophyte community variables, supporting the hypothesis that site-scale development intensity is related to littoral vegetation. Negative effects of lake-wide development were not detected in whole lake macrophyte and fish community metrics.