PORT CLINTON — Lake Erie’s harmful algal bloom has been shrinking for about one or two weeks, but scientists don’t know yet when it will disappear.
“The cyanobacteria bloom in western Lake Erie has an approximate area of 120 square miles, which is a decrease in area since Sept. 14. The cyanobacteria bloom extends from Stony Point, Michigan, to about Port Clinton, Ohio,” Andrew Meredith of the National Oceanic and Atmospheric Administration wrote on Wednesday.
"The western basin bloom is a mix of microcystis and dolichospermum. Sandusky Bay has a local bloom of mixed cyanobacteria,” Meredith wrote.
Algal blooms are produced by cyanobacteria, bacteria which behave like algae. Microcystis is the most common form of cyanobacteria producing harmful algal blooms in Lake Erie.
Last year’s bloom behaved differently from blooms in previous years, so that makes it harder to predict when the bloom will go away, said Richard Stumpf, an oceanographer for the atmospheric administration who focuses much of his attention on Lake Erie’s harmful algal blooms.
“While the bloom has weakened in the past two weeks, we cannot currently predict either when it will end or when it will be so small as to be inconsequential,” Stumpf wrote in an email responding to the Register’s questions.
“Typically, it diminishes through September and is usually gone at the beginning of Oct. 1. This is encouraged by dropping temperature and regular occurrence of stronger winds,” Stumpf explained.
“However, last year, we had a different cyanobacteria species bloom about Oct. 1, and it produced a small but fairly intense bloom. That was new, so we don't know why it happened,” he wrote.
Stumpf and other scientists gathered at Stone Laboratory near Put-in-Bay in late June and issued a forecast for the 2023 harmful algal bloom, predicting a relatively small bloom this year. They forecast a bloom that would measure as a 3 in size, on a scale of 1 to 10, with a potential range in severity from 2.5 to 4.
Asked how that forecast is holding up, Stumpf replied, “The bloom started early, and was a bit more intense than originally expected. We'll have specifics in October.”
