The Great Lakes at Risk

AN algal bloom on Lake Erie. Image: NASA

by Ashira Morris, ODP Contributing Writer

Collectively, the Great Lakes are the world’s largest freshwater system. They provide drinking water, food, even the fresh air we breathe. The five lakes are “arguably the continent’s most precious resource,” National Geographic writes in the magazine’s December cover story. 

And they’re in trouble. Toxic chemicals from agriculture, invasive species, and warmer water temperatures because of the climate crisis are throwing the lakes into an unhealthy state. Greenhouse gas emissions have created new weather patterns, causing more intense storms to blow off the lakes.

To break down just one threat: fertilizer runoff from farms and manure from industrial animal farms are causing more frequent and more intense cyanobacteria outbreaks. The algae forms a green, scummy barrier on the surface, blocking oxygen from reaching the aquatic plants and animals that need it. It’s also harmful to people and pets: toxic algae outbreaks have been linked to liver damage and dog deaths

Why This Matters: The Great Lakes watershed is home to almost 40 million Americans and Canadians. Each individual human-introduced harm to the lakes is a challenge on its own that threatens the health of the people and ecosystems reliant upon these bodies of water. 

On Lake Erie, which faces the most phosphorous pollution, half a million people already directly felt the impact of intense algae outbreaks. The city of Toledo gets its water supply from the lake, and for two days in 2014, the city water supply was poisoned by algae. 

“It was a traumatic event for our region,” Wade Kapszukiewicz, Toledo’s current mayor, told National Geographic.

Fertilizer runoff is mostly unregulated by the Clean Water Act, but without stricter phosphorus runoff regulations, the outbreaks will become a permanent fixture. Climate change will only make them more intense.

Shrinking Microalgae Has A Big Impact: Some of the changes happening on the Great Lakes are harder to see on the surface. The lakes’ tiny diatoms are an essential base of the Great Lakes food chain. The diatoms are a good kind of microalgae, and they’re being eaten by invasive mussels and shrinking because of climate change — they sink deeper in warmer water, reducing their ability to photosynthesize.

The trend is smaller diatoms and less of them, and they’re being replaced by things that are at best low-quality food items and at worst toxic,” Andrew Bramburger, a lake ecologist now with Environment and Climate Change Canada, told NatGeo. “We don’t know what that’s going to do to the overall food web.”

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