Researchers identify factors causing algae blooms on Lake Superior


LAKE SUPERIOR, Mich. (WLNS) – Researchers think they know why algae blooms are happening on Lake Superior.

Although there’s no evidence of toxicity in Lake Superior blooms so far, researchers from the University of Minnesota Duluth are monitoring it closely to see what triggers these blooms.

“We’ve seen either small or large blooms of blue-green algae along the south shore of Lake Superior between the Twin Ports and the Apostle Islands. This falls under the general subject of harmful algal blooms,” said Bob Sterner, the director of UMD’s Large Lakes Observatory and the lead researcher of these blooms.

Sterner has been doing extensive research in partnership with the National Park Service since 2011, according to a report from WDIO.

“These blooms in other lakes are known to be harmful to food webs. Whether that’s happening in Lake Superior or not we can’t really say yet but these dense cyanobacteria populations degrade water quality in several ways,” said Sterner. He added that these toxins can be dangerous to fish populations as well.

“One of my worries is just what it means for the quality of this resource and how people interact with it. If the reputation of Lake Superior changes from it’s always cool, clear and pristine to a polluted environment where we have algal blooms, that change in reputation might be harmful to recreation and tourism,” said Sterner.

The team has identified two major factors that contribute to the presence of these blooms, a warm year, combined with major weather events or historic rainfall. Sterner said we’ve had a warm year so far.

“The largest of these blooms have occurred in 2012 and 2018. 2012 is the infamous year when the rainstorm tore out a lot of infrastructure in Duluth and 2018 was a similarly large rain event,” said Sterner.

Sterner said they’ve seen small blooms but the samples they’ve gathered have not shown dangerous levels of toxicity. He said certain environmental factors like high nitrogen levels can trigger it and added that we can do our part to help if we see floating green scum.

“We urge people if they see a bloom in Lake Superior to stay out of the water, keep your pets out of the water and please report it to either the Wisconsin or Minnesota DNR,” said Sterner.

To report the bloom, take a picture as well as writing down the location, size, and time it was seen. Additionally, safely collect a water sample if you can.

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