Effects of Channel Modification and Flow Augmentation on Freshwater Mussels in the Bayou Meto Area, Arkansas

摘要

A survey for freshwater mussels (Family: Unionidae) was conducted in the Bayou Meto area (including Bayou Meto, Bayou Two Prairie, Crooked Creek, Indian Bayou, Salt Bayou Ditch, Wabbaseka Bayou, and associated miscellaneous ditches) near Stuttgart, AR, in the spring of 2001. Approximately 19 hr of search time was expended at 45 sites in the study area. A separate search of five sites on Plum Bayou was conducted on 18 September 2001 to search for zebra mussels (Dreissena polymorpha). The overall purpose was to census the mussel fauna in the area to determine impacts of proposed channel modification (clearing, snagging, and channel enlargement by dredging) and proposed flow augmentation. Using both qualitative and quantitative methods, more than 1,000 individuals and 18 species of mussels were collected. The majority of the mussels were found at two sites in Indian Bayou (86 percent of the total), and approximately 13 percent were obtained at seven sites in Salt Bayou Ditch. No live mussels were found in Bayou Meto and adjacent ditches, and 1.14 percent of the total found were collected in Wabbaseka Bayou. No Federally listed endangered or threatened species were found. The fauna was dominated by Amblema plicata and Ouadrula quadru1a that together comprised more than 80 percent of the fauna. Overall, molluscs in the project area were negatively affected by low flow, high temperatures in the summer, and substratum that consists mainly of sand, silt, and organic matter. At sites where mussels were collected, the density and diversity were low, and populations exhibited little evidence of recent recruitment. The proposed channel modification will negatively affect mussels in stream channels, although removing debris and increasing flow will ultimately benefit most aquatic organisms, including the mussels. Zebra mussels are in the Arkansas River and are likely to be brought into these bayous by this project; live specimens were found in Plum Bayou.