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Research Scientist
University of Michigan

Gary Fahnenstiel’s knowledge and understanding of the ecology of the Great Lakes places him among a handful of top Great Lakes scholars in the world. He worked for nearly 30 years at the National Oceanographic and Atmospheric Administration’s (NOAA) Great Lakes Environmental Research Laboratory (GLERL) prior to joining the U-M Water Center. He is a leading freshwater biologist, with expertise in ecosystem dynamics, invasive species, and phytoplankton ecology (the study of free-floating plants such as algae).

Much of Fahnenstiel’s recent work has focused on increases of harmful algal blooms (HABs) in the Great Lakes. Most species of algae are not harmful and are in fact a vitally important part of freshwater ecosystems, but some algae can grow very quickly in response to changes in water chemistry. Nitrogen and phosphorous from fertilizers primarily enter the Great Lakes as runoff from lawns and agricultural fields, and can result in water chemistry changes that contribute to the occurrence of HABs. These rapidly growing algal blooms produce toxins that can harm the health of the environment, plants, animals, and people. HABs can threaten drinking water sources and lead to beach closures, negatively impacting Michigan’s tourism and recreation industries.

Fahnenstiel has been working on identifying particular environmental factors that lead to HABs with the aim of helping to better manage and reduce their occurrence. He also works more broadly to determine how different environmental stressors, such as excess nutrients and climate change, interact to negatively impact coastal ecosystems.