Principal Investigators: Edward Rutherford (CILER), and Gary Fahnenstiel (NOAA/GLERL)

A resurgence of harmful algal blooms in the Great Lakes has occurred in the last decade. These events were surprising given the success of eutrophication controls. These new HABs appeared to be related to the arrival of recently established non-indigenous species, particularly mussels of the genus Dreissena. Toxic cyanobacteria, e.g, Microcystis, have been most often associated with these new Great Lakes HABs, and these new HABS do not appear to be diminishing. The presence of these cyanobacterial blooms (HABs) in the Great Lakes is of considerable concern due to their ability to produce toxins (e.g., microcystin) than can be detrimental to human and ecosystem health. Microcystin concentrations higher than the World Health Organization’s (WHO) recommended limit for drinking water (1 µg L-1) were found throughout western Lake Erie and Saginaw Bay during the summers of 2004-2006 and concentrations exceeding 200 µg L-1 (ten times the WHO’s recommended limit of 20 µg L-1 microcystin for recreational use) were measured in inland lakes and surface scums. The results of these monitoring efforts were posted on the HAB Event Response website in order to facilitate public awareness of potentially high levels of microcystin in surface recreational and drinking water supplies. The Harmful Algal Bloom Event Response website has been a very successful outcome of the research programs at GLERL. Providing the data for the website has fostered a productive collaboration between researchers using different modes of detection for cyanobacterial blooms by combining satellite-based imagery to identify potential bloom locations with ground-based measurements of cyanobacterial biomass and toxin in surface waters. There has been a very positive response to this website both within the scientific and the local communities.