Warmer waters fuel toxic cyanobacteria blooms in the Great Lakes
Big, ugly blooms of cyanobacteria (sometimes referred to as blue-green algae) are reappearing in the western basin (and sometimes the central basin) of Lake Erie.
The blooms happen when excess nutrients – mostly phosphorus – run off into the lake from farms and sewage treatment plants.
Some of these kinds of cyanobacteria produce toxins that are among the most powerful natural poisons on Earth.
Over the past decade, these cyanobacteria blooms have been common in Lake Erie. And scientists predict climate change could make the problem worse.
Toxic green goo
Frank and Sandy Bihn took us out on a boat ride in Maumee Bay near Toledo. Sandy’s the executive director of the group Lake Erie Waterkeeper.
Another boat passes us and Frank waves his arm excitedly.
“Look at the green wave! Look, see them stirring it up? Look at this wake over here!”
The water out here looks like pea soup. The cyanobacteria that’s blooming here is called Microcystis and it produces a dangerous toxin.
Sandy Bihn says you wouldn’t want to swim in it — and you shouldn’t.
“If your dog gets immersed in it and the toxins are there, it can kill the dog, a very good sized dog. We know a person who actually became sick with neurological disorders because of it,” she says.
Cities around here also pull their drinking water from the lake.
“They have to treat the water more and take the algae out, and it costs them more and increases the cost of the treatment process.”
Last month, 2,000 people in a northwest Ohio township were told not to drink their tap water because levels of the toxin were so high.
The Ohio Environmental Protection Agency says it’s safe to eat the fish from the lake, but it recommends removing the guts and liver and rinsing the fillets in tap water first.
Jamie Matuzak is a Lake Erie Waterkeeper board member. Here she explains how the lake has changed over the years:
Algae and fishing don't mix well
Lake Erie is called the Walleye Capital of the World for a good reason. But people who fish for a living say the blooms have made things tougher for them.
Paul Pacholski is the Vice President of the Lake Erie Charter Boat Association.
“When you have algae so thick you can actually write your name with a fishing pole in it, people think of it as going back to the '60s when it was called a dead lake.”
The blooms they saw in the past are back.
In 2011, there was an epic harmful cyanobacteria bloom in Lake Erie that smashed all the records. Pacholski says he had to run his customers way out into the lake to try to get away from it. He burned through a lot more gas and a lot more money.
“You lose business. You have people who will never come back.”
So, what about the fish?
There are a lot of big open questions about what these blooms mean for fish.
Jeff Reutter directs Ohio State University’s Stone Laboratory, here on South Bass Island in Lake Erie.
One thing researchers know for sure is that cyanobacteria blooms can cause dead zones. In Lake Erie’s central basin, the cyanobacteria can die and sink to the bottom. Decomposing bacteria eat up that dead cyanobacteria and rob the water of oxygen at the bottom of the lake.
“All the fish either move out or they’re killed,” explains Reutter.
He says they’re planning to study how the microcystin toxin produced by cyanobacteria affects fish, and see if the blooms change their behavior. They want to know if some fish like the shade and cover of the bloom - or if they flee from it.
Reutter says climate change is expected to make these algal blooms worse. For one thing, the water is warming and that favors blooms.
“The other thing we’re seeing is the frequency of severe storms has greatly increased and is continuing to increase. The storms that produce more than three inches of rain in a 24 hour period – those storms have increased over 50% in the last 50 years,” he says.
He says when those heavy storms happen in the spring they can flush phosphorus from farm fields into the lake, and all those extra nutrients can put the blooms on steroids.
Farmers and fishermen and scientists are scrambling to find ways to solve this. The people who live and work on the lake hope it doesn’t take too long.
In this short clip, Lake Erie Waterkeeper Sandy Binh explains why she thinks problems like these get overlooked:
Clarification: An earlier version of this story referred to "algae blooms" in Lake Erie. These are really bacterial blooms (cyanobacteria) that look like algae. The copy has been clarified above.