Binational efforts addressing cyanobacterial harmful algal blooms in the great lakes

Cyanobacterial harmful algal blooms (cyanoHABs) are a recurring impairment in many of the lakes and connecting water bodies that make up the Laurentian Great Lakes. In many of these lakes, eutrophication during the twentieth century resulted in shifts in summer phytoplankton populations to communities dominated by harmful and noxious colonial and filamentous cyanobacteria. Nutrient pollution of Lake Erie was an important factor behind the implementation of the 1972 Great Lakes Water Quality Agreement between the USA and Canada. While the GLWQA has been effective in targeting point sources of nutrient loading, nonpoint source contributions related to agricultural activity have increased in recent decades. Re-eutrophication as experienced in parts of western Lake Erie and portions of the other Great Lakes is exacerbated by global climate change with these factors collectively contributing to a resurgence in the frequency and severity of cyanoHABs. As the Laurentian Great Lakes are shared waters between the USA and Canada, successful mitigation of cyanoHABs will require increased binational coordination