Scientists predict harmful algal bloom in Lake Erie
CLEVELAND — Researchers are predicting a harmful algal bloom in western Lake Erie that is less severe than last year’s moderate bloom and perhaps more like the mild event in 2020, if early season projections “of near or below average rainfall” pan out for the remainder of spring.
The early season bloom projection, announced by the National Oceanic and Atmospheric Administration and the National Center for Water Quality Research, is based on observations through May 15. It will be updated weekly with a comprehensive seasonal forecast on June 30.
The most severe bloom over the past 20 years was recorded in 2015 when the severity index was 10.5, followed by 2011 at 10.
Toxins in the algal blooms can be harmful, even fatal to people and animals. In 2014 they threatened the Toledo water supply.
Last year’s severity index was 6, which is moderate, said Laura Johnson, director of the National Center for Water Quality Research. It “wasn’t super concentrated in one spot,” but it was very widespread, she said, and because of heavy rain in July and a warm fall, it lasted a long time.
In 2020 the bloom had an index of 3. It was relatively short-lived because there was not much nutrient loading in June or July, Johnson said.
The primary cause of the harmful algal blooms is the phosphorus nutrient that runs off farms and into the Maumee River, which feeds Lake Erie. The amount of rainfall impacts the volume of phosphorus that ultimately makes it into the lake.
The severity of the bloom does not necessarily correspond with the amount of toxins that are produced by the algae, Johnson said, “but if we had no bloom there would be no toxins.”
She said research is being conducted into what turns the bloom toxic, she said, but you can be sure that if the water has scum on top of it that toxins are present.