Linking weather patterns, water quality and invasive mussel distributions in the development and application of a water clarity index for the Great Lakes

The Great Lakes contain 84% of the fresh water in North America and provide many critical and valuable ecosystem services to lakeside communities. In the past decade, a rapid ecosystem regime shift has occurred where changing precipitation and runoff patterns, along with invasive zebra and quagga mussels, have contributed to dramatic lake-specific responses in water clarity, reductions in phytoplankton, increases in toxic algal blooms, and disruptions in the food chain. Focusing on Lake Michigan, this study applies a newly improved remote sensing algorithm for water clarity and integrates meteorological data and in-situ sampling of mussels to understand the spatial and temporal linkages between historical weather patterns, water clarity and mussel abundance. Results from a decade of satellite-derived ocean color images reveal the complex spatio-temporal patterns of ‘bio-clarification’ occurring in Lake Michigan. Mussel biomass was negatively correlated with phytoplankton concentrations and turbidity, but association was likely weakened by unmeasured variables such as nearshore runoff, patterns of plankton and nutrient dynamics, thermal structure and mixing.