Warmer Lakes Lead To Toxic Algae Increases, Study Finds

Jan 12, 2016

Rapidly warming surface water temperatures in lakes around the world are threatening freshwater supplies and ecosystems. That's according to a 25-year study of 235 lakes on six continents.

Scientists, including co-author and Miami University professor Craig Williamson say climate change is to blame. Warmer surface water temperatures are a problem, he says, because they lead to harmful blue-green algae blooms in lakes used for recreation and drinking water.

"These are algae that in freshwater systems can produce neurotoxins and hepatotoxins, so brain toxins and liver toxins," says Williamson. "And they tend to do better under warmer conditions."

Williamson says wildlife, especially fish, are at risk from the toxic blooms as well.

Rapidly warming waters alone can have a negative impact on animals. Miami University writes:

"Seals in Russia's Lake Baikal are a species that will be affected by lake warming."
Credit Provided / S. Gabdurakhamanov, CC-BY-2.0

The study found lake surface water temperatures are warming an average of 0.34 degrees Celsius, or 0.61 degrees Fahrenheit, each decade. That’s greater than the warming rate of either the oceans or the atmosphere, and it can have profound effects, the scientists said.

The study projects a five percent increase in toxic algal blooms during the next century. Though the 235 lakes studied are a small portion of global lakes, the study says they make up more than half of the world's freshwater supply.

The study found lake surface water temperatures are warming an average of 0.34 degrees Celsius, or 0.61 degrees Fahrenheit, each decade. That’s greater than the warming rate of either the oceans or the atmosphere, and it can have profound effects, the scientists said.

Partial funding came from NASA and the National Science Foundation. Miami reports the study is the largest of its kind.

The study's findings were published in a recent issue of Geophysical Research Letters.

Williamson says the research will now shift to deeper water. Research associate Rachel Pilla plans to examine changes in deeper water "as well as surface temperatures in a suite of more than 100 lakes from around the world."