Abstract
In 2005, NOAAs Great Lakes Environmental Research Laboratory (GLERL) organized the international field year on Lake Erie (IFYLE). This concentrated effort offered an unparalleled opportunity to examine the spatial and temporal distribution of toxic cyanobacteria in all three basins of Lake Erie over an entire growing season. Research cruises were conducted monthly from May through September and samples collected from 54 stations for toxin and chlorophyll analysis. More than 320 samples have been analyzed for microcystin and anatoxin- a toxicity. Hepatotoxic microcystins were found during several distinct toxic events in the western basin. Sandusky Harbor showed consistent microcystin toxicity from May through September with levels approaching 1 ug/L. Similar levels of toxicity were found near the Maumee River in July and lower levels (0.1-0.2 ug/L) were observed near western basin islands in August and September. In all cases, the maximum levels of microcystin were less than 1 ug/L. None of the stations in the eastern or central basin contained significant levels of microcystins. Levels of the neurotoxin anatoxin-a were consistently low (< 0.1 ug/L), and also confined to the western end of the lake during August and September. Analysis of the algal species responsible for toxin formation is currently in progress.