RANGE EXTENSION OF THE FEDERALLY ENDANGERED WINGED MAPLELEAF MUSSEL: SHELLS COLLECTED FROM THE UPPER ST. CROIX RIVER

Mark C. Hove, Leda A. Cunningham, Katie G. Esse, and Daniel J. Hornbach

Macalester College, Biology Department, 1600 Grand Avenue, St. Paul, MN 55105. Email address: Mark.Hove@fw.umn.edu

Work conducted this summer extends the range of the winged mapleleaf to the upper St. Croix River. The historic distribution of the species ranged throughout the upper Mississippi River basin including 34 rivers across 12 states. Since the 1920's the community has declined drastically to where now only two small populations are known, one in the Ouachita River, Arkansas, and the last known reproducing population in the lower St. Croix River. Prior to this summer the winged mapleleaf had only been observed in the lower St. Croix River (the reach downstream of the falls). This summer three winged mapleleaf shells were collected at Wild River State Park, Minnesota. Two of the valves are worn and old, the other valve is less eroded and may have been deposited more recently. Ten sites were surveyed for live winged mapleleaf 1 mile upstream and downstream of the western Wild River State Park boat launch but none were observed. The mussel community at Wild River State Park is diverse and robust. It is difficult to ascertain the cause(s) for the status of winged mapleleaf in this portion of the river. Some thought should be given to the suitability of this habitat if it is to be considered as a relocation site for winged mapleleaf should zebra mussels threaten the population in lower reach of the river.