Lauren Villalobos ACF Abstract FY11

"ECOSYSTEM RESPONSES TO LOW-HEAD DAM REMOVAL: ASSESSMENT OF PHYSICAL HABITAT, WATER CHEMISTRY, AND MACROINVERTEBRATES"

North American Benthological Society Annual Meeting

Lauren Villalobos

This two year study focused on understanding the effects of dam removal on
the low-head Nashville dam on the Thornapple River, Barry County, MI. A comparison of data taken from pre to post dam removal indicated changes to the physical habitat, water chemistry, and macroinvertebrate communities. In the reach directly below the dam there was an increase in fine sediment, causing an average cross-sectional channel aggradation of 26 cm, indicating reservoir erosion and subsequent downstream deposition. For macroinvertebrate communities, the percent EPT on artificial substrate increased from an average of 27 to 64 at all sites below the former reservoir (P&#60 0.05). Further, in 2009 Isopods dominated the site directly below the dam, with an average of 222 Isopods at all downstream sites. In contrast there was an average of 4 isopods per site in 2010. Our results suggest that the removal of a low-head dam improved the macroinvertebrate community immediately below the dam, while the habitat quality is still degraded, but the impacts are proximate to the former dam site.