Algae Blooms Relatively New to Lake Superior
Blue-green algae, or cyanobacteria, usually doesn’t bloom in the cold nutrient-poor waters of Lake Superior. Optimal water temperatures required for algae blooms are in the range of 25C (77F) and Lake Superior’s average surface water temperature is usually closer to 15C (59F).
The first recorded algae bloom in the Lake occurred in July 2012 when record breaking lake temperatures were reached. Researchers believed that higher than average water temperatures, combined with flooding that added nutrient-rich sediment to the lake, was what led to the 2012 bloom. The same factors were involved in a 2016 bloom.
Continued Heating and Major Storms in 2018
The most recent algae bloom on Lake Superior was observed in mid-August, 2018, and it seems to indicate that water temperature and flooding are indeed major factors. This summer has seen record breaking temperatures and prolonged heat waves, which has translated to warmer lake temperatures. Major flooding dumped significant amounts of sediment into Lake Superior along the same stretch of coastline where the algae bloom was reported—from Superior Wisconsin to the Apostle Islands.
Scientists do not fully understand the relationship between these factors and Lake Superior algae blooms, but they are looking into it. Blue-green algae has the potential to be toxic to humans, pets and wildlife. Samples were collected and have been sent for testing but the algae has now dissipated and no reports have been made to indicate that the bloom had any major effects on water safety in the region.
Related:
August 29th, 2018 Article in New York Times – “Algae Bloom in Lake Superior Raises Worries on Climate change and Tourism”
November 29th, 2016 Infosuperior Article – “It Could Never Happen Here“