The bloom boom: increasing frequency of algal blooms may be due to climate change

Algal blooms could be growing more frequent due to climate change, say University of Minnesota researchers.

by Katie Salai

With summer approaching, University of Minnesota researchers are seeking more accurate methods to predict algal blooms. 

In a paper to be submitted by the University of Minnesota’s Department of Civil, Environmental, and Geo-Engineering at the end of the semester, researchers are analyzing the increasing frequency of algal blooms and how to track them more accurately. Due to impacts of climate change and the adaptability of algae, frequency of blooms can greatly vary.

“We know that they happen in the summer, and that’s about the best we can do,” said Jackie Taylor, Ph.D. student and researcher in the University’s St. Anthony Falls Laboratory. Taylor said their models of algal patterns can be used by water systems managers to better predict harmful algal blooms.

To predict algal blooms, like a weather forecast prediction, Taylor said the role of hydrodynamics is key. Large storm events bring greater deposits of nutrients quickly, which may be more important than the level of nutrients themselves.

“In Lake Superior, near-shore algal blooms — especially in the Apostles [Islands] — have gotten more noticed since 2012,” said Elizabeth Minor, professor and chemist in the Large Lakes Observatory at the University of Minnesota-Duluth. “There appears to be some relationship between having these extreme events. And then three weeks, five weeks, six weeks later, we tend to see these near-shore algal blooms.”

Ecologically, algal blooms reduce the amount of oxygen in lakes, leading to poor water quality and reduced habitats for fish. Toxins produced by blooms in the water are known to be harmful to humans. 

Impacts of climate change can be seen in storm events and the lengthening summer growing period for algae. Minor said Lake Superior’s algal growing season is almost a month longer today than in the 1980s. Rising water temperatures and increased rainfall leading to algal blooms can also undo current work for improving lake quality.

“There’s a little bit of a convergence in terms of … some of the worst lakes have gotten a little bit cleaner, and many of our cleanest lakes have gotten a little bit worse,” said Jacques Finlay of the University’s Institute on the Environment. 

Greater precipitation can also lead to greater agricultural runoff that hasn’t been absorbed and filtered by the ground.

“In the case of snowmelts, in particular, if you get a bunch of snowmelt at the beginning of the season, you’re getting a bunch of nutrient loading at the beginning of the season,” said Taylor. 

A lake’s geometry also causes varying algal bloom possibilities. A deeper lake would see a more pronounced impact due to greater energy needed to mix the nutrients released into the water by storm events.

Taylor said algae is resilient and able to survive “when things get weird,” such as in high turbulence or low-light conditions. 

“They’re good at surviving because they’re good at forming communities,” said Taylor. “Maybe instead of treating them as an enemy, in a more philosophical context, we can kind of try to learn from them.”