THE MONITORING OF FRESHWATER MUSSELS WITHIN THE APOSTLE ISLANDS REGION AND THEIR POTENTIAL AS BIO-INDICATORS

Doolitle, Thomas

There were six unionid taxa collected live in the survey. The most abundant species found was Elliptio complanta and Anodonta g. form grandis exhibited the greatest distribution. A topo form of white heel splitter (Lasmigona c. complanata) was the least common. Previously not recorded live from Wisconsin Lake Superior waters were Anodontoides ferussacianus, Anodonta cataracta marginata and Lasmigona c. complanata. Range extensions in Wisconsin were noted for, Anodonta g. form grandis, Anodontoides ferussacianus, Anodonta cataracta marginata, Lampsilis radiata siliquiodea, Elliptio complanata, and Lasmigona c. complanata. The known latitudinal limit for unionid mussels in Wisconsin was recorded in Sand Bay. Density of mussels were low. The mean density of mussels for all transects (n=22) was 7.3 mussels/60m^2. Random grab surveys (n=8) noted a mean of 39 mussels/hour. A vast mussel bed, exceeding 10km^2 was located off the Chequamegon Bay side of Long Island. Transects insufficiently sampled low density species, but provided an appropriate mechanism to determine relative abundance and density for common species. Random grabs were appropriate to not presence of uncommon species. Generally, the mussel beds sampled were healthy. The exceptions may be the Red Cliff Bay mussel bed and the white heel splitter population in Raspberry Bay. The extent of the Long Island bed should be quantified, since this bed may be suceptible to commercial harvest. Additional taxonomic work is needed on Lasmigona c. complanata, Anodonta cataracta marginata and Anodonta g. form grandis. Freshwater mussels would be useful as an aquatic monitor for the Apostle Islands region.