Figure 1. Specimen from upper Saint Croix River.
Range extension of the federally endangered winged mapleleaf: valves collected from upper Saint Croix River, Minnesota
Mark C. Hove, Leda A. Cunningham, Katie G. Esse, and Daniel J. Hornbach
Macalester College, Biology Department, 1600 Grand Avenue,
St. Paul, MN 55105.
Phone (651) 696-6827, email address: Mark.Hove@fw.umn.edu
Work conducted this summer extends the range of the winged mapleleaf, Quadrula fragosa (Conrad, 1835), to the upper St. Croix River. The historic distribution of the species included much of the upper Mississippi River basin including 34 rivers across 12 states (U.S. Fish and Wildlife Service 1997). Since the 1920's the community has declined drastically to where only two small populations of winged mapleleaf are now known, one in the Ouachita River, Arkansas (Posey et al. 1996), and the last known reproducing population in the St. Croix River, Wisconsin (Hornbach et al. 1996). Recent surveys reported the presence of the species only in the lower St. Croix River.
This summer three winged mapleleaf valves were collected at Wild River State Park, Minnesota. Two pairs of valves were collected during a mussel relocation study. One pair is worn and old, the other is less eroded and may have been deposited more recently. To determine if live winged mapleleaf occurred nearby the U. S. Fish and Wildlife Service funded a small survey of the area. We surveyed ten sites within one mile of Wild River State Park with SCUBA. At each site a 15 minute timed search for all live mussels was conducted followed by a 90 minute search for live or dead winged mapleleaf. During the survey an additional subfossil winged mapleleaf valve was collected at the location where the first two valves were found. Unfortunately no live winged mapleleaf were observed. We are seeking additional species identification confirmation for the three valves.
During the survey we also collected an unusual purple wartyback (Cyclonaias tuberculata) with flutings along its dorsal and much of its posterior margin. Images of the animal are available on a link to our web page (http://www.macalstr.edu/~hornbach/). We are interested in learning if this phenotype is common or not. Please visit the web sight and share your experience.
It is difficult to ascertain the cause(s) for the status of winged mapleleaf in this portion of the river. The mussel community at Wild River State Park is diverse and robust. Some thought should be given to the suitability of this habitat if it is to be considered as a relocation site for winged mapleleaf.
Funding for the project came from the U.S. Fish & Wildlife Service, and Minnesota Legislature,1999 Minnesota Laws, Ch. 231, Sec. 16, Subd. 15b as recommended by the Legislative Commission on Minnesota Resources from the Minnesota Environmental Trust Fund. We thank Lisie Kitchell for assistance in the field.
Literature Cited
Hornbach, D. J., J. G. March, T. Deneka, N. H. Troelstrup, and J. A. Perry. 1996. Factors influencing the distribution and abundance of the endangered winged mapleleaf Quadrula fragosa in the St. Croix River, Minnesota and Wisconsin. American Midland Naturalist 136(2): 278-286.
Posey, W. R., J. L. Harris, and G. L. Harp. 1996. New distribution records for freshwater mussels in the Ouachita River, Arkansas. Proceedings Arkansas Academy of Science 50: 96-98.
U.S. Fish and Wildlife Service. 1997. Winged Mapleleaf Mussel (Quadrula fragosa) Recovery Plan. Ft. Snelling, Minnesota.