LiDAR and bottom reflectance studies: migrating tailings threaten Buffalo Reef in Lake Superior

Session: Great Lakes Reefs: Research, Monitoring, Creation, and Maintenance (1)

W. Charles Kerfoot, Michigan Technological University, Great Lakes Research Center and Dept. of Biological Sciences, [email protected]
Martin Hobmeier, Michigan Tech. University, Dept. Biology, [email protected]
Robert Regis, Northern Michigan University, [email protected]
Varsha Kausika Raman, Michigan Technological University, [email protected]
Colin Brooks, Michigan Tech Research Institute, [email protected]
Robert Shuchman, Michigan Technological University, [email protected]
Mike Sayers, Michigan Tech. Research Inst., [email protected]
Foad Yousef, Michigan Tech Univ, [email protected]

Abstract

Due to excellent penetration in marine and northern Great Lakes waters, light detection and ranging (LiDAR) aids environmental studies of coastal environments. On the Keweenaw Peninsula of Lake Superior, between 1901-1932, two stamp mills (Mohawk and Wolverine) discharged 22.7 million metric tonnes of tailings (stamp sands) off the town of Gay. The tailings are now threatening critical fish breeding grounds. Buffalo Reef is important for commercial and recreational lake trout and lake whitefish production (32% of the commercial catch in Keweenaw Bay, 22% of southern Lake Superior). Aerial photographs and five LiDAR over-flights emphasize: 1) the enormous amounts of stamp sands moving along the shoreline, and 2) equally large amounts migrating underwater across the bay. Differences from LiDAR digital elevation models (DEMs) are used to quantify underwater stamp sand bar movement. Stamp sand overflow out of the northern “trough” is now moving into Buffalo reef cobble fields, where fish drop eggs. Ponar sediment studies quantify % stamp sand and Cu concentrations in sand mixtures, and confirm impacts on benthic invertebrate taxa. Our study emphasizes that when large amounts of mine tailings are discharged into coastal environments, temporal and spatial impacts are progressive and can threaten bay ecosystems and commercial fishing.