Mussel survey and population assessment, 2017: Apostle Islands National Lakeshore
Lafrancois T, Hove M, McCartney M. 2019. Mussel survey and population assessment, 2017: Apostle Islands National Lakeshore. Natural Resource Report. NPS/APIS/NRR—2019/1867. National Park Service. Fort Collins, Colorado
Native pearly mussels (Bivalvia: Unionidae) are benthic filter feeders with a unique life cycle including a non-harmful parasitic stage on fish. Their sensitivity to environmental changes and associations with their host fish make them an ideal sentinel species in aquatic ecosystems. Unionids also function as pelagic food web integrators making them cornerstones of food web, contaminant bioaccumulation, and other related studies. Mussels have historical economic and cultural importance to coastal communities in the Great Lakes region. A 1991 SCUBA-based survey of the Apostle Islands National Lakeshore found several beds of mussels and no invasive zebra or quagga mussels (Bivalvia: Dreissenidae). Since that time, both zebra and quagga mussels have been detected in the Apostle Islands. This survey reprises the 1991 survey with the addition of a few sites where native and non-native mussels have been incidentally encountered by NPS divers. Zebra mussels (Dreissena polymorpha) were collected near Sand Island, Stockton Island, and in Red Cliff Bay and genetically identified. No quagga mussels (Dreissena bugensis) were found at study sites. Native mussels were found at all sites where they were previously reported as well as in Quarry and Presque Isle Bays of Stockton Island, where mussels were not found in 1991. Principal components plots reveal three distinct community types that explain between 31% and 48% of the variation in community composition depending on whether zebra mussels are included. The native mussel bed near Long Island is thriving, increasing in density between 1991 and 2017 with observed signs of recruitment. Mussel populations in Red Cliff and Raspberry Bays have declined in density. The lagoon on Stockton Island and the Sand Bay area show no major changes. Three species previously reported in the area were not found in 2017 and are potentially extirpated pending confirmation by further study.
- Type
- Published Report
- Authors
- Lafrancois, Toben; Hove, Mark; McCartney, Michael
- Date of Issue
- 2019-02
- Publisher
- National Park Service
- Units
- APIS , GLKN , NRSS
- Keywords
- Apostle Islands, Dreissena, GLKN General, Lake Superior, mussels, Unionidae