U.S. Lakes Face Rising Algae Threat from Climate Change

Michigan State University Findings on Algae Bloom Dynamics Offer New Insights

Michigan State University (MSU) have found that the health of thousands of lakes across the United States is affected by both climate change and human activities, such as farming and urban runoff. Their study explains why harmful algal blooms, which cause lake beaches to close each summer, are becoming more common.

The team analyzed chlorophyll levels, an indicator of algae growth, in over 24,000 lakes using satellite images and public data from the past 34 years. They discovered climate impacts on lakes were not simple or predictable.

About one-third of the lakes studied experienced climate-driven changes in algae. Surprisingly, most changes were abrupt but temporary, rather than gradual increases in algae growth.

Professor Patricia Soranno from Michigan State University (MSU) explained the complexity - “Our research demonstrates that the relationship between climate change and algal biomass is more complex than expected. While climate is a significant driver of algal biomass, we found that the impacts are not always gradual or predictable. To effectively manage and protect lakes, we need to study these effects in many different local and regional contexts.”

This research also revealed a critical insight: lakes with low to moderate human disturbances responded more noticeably to climate change. In contrast, lakes heavily impacted by human activities—especially those receiving nutrient-rich runoff from farms—showed weaker connections to climate shifts.

This data-intensive approach also uncovered variability in climate-driven algal responses that depend on environmental conditions and the level of human disturbance.

Lakes with low to moderate human impacts were more likely to respond to climate, while lakes already under heavy human pressures, like increased nutrient input from agriculture, were less likely linked to climate.

The Michigan State University researchers suggest that lake management efforts must consider both climate effects and human activities like agriculture and urban development. Understanding these combined impacts is key to protecting lakes and ensuring cleaner water for the future.

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