Better understanding the persistence of HABs on Lake of the Woods through high-frequency monitoring

Lake of the Woods, one of the largest lakes in North America, has been designated as an impaired water due to elevated nutrients and the persistence of harmful algae blooms (HABs) in its shallow southern basin. These blooms continue to occur decades after major reductions in point-source phosphorus pollution and a watershed predominately composed of protected forest. Here, we draw on more than a decade of work on Lake of the Woods using paleo- and neo-limnological techniques that have documented the rise and fall of HABs prior to and following the Clean Water Act, and the recent resurgence of a new, potentially more toxic, community of nitrogen-fixing cyanobacteria in the lake that may be responding to shifts in nutrient stoichiometry and changing patterns in thermal stratification related to climate change. Understanding the trajectory of HABs in Lake of the Woods has required new monitoring techniques, including the deployment of high-frequency sensors and sediment traps, as well as dedicated partnerships between diverse stakeholders, including federal, tribal, and state resource managers. The continued dominance of the southern basin by Cyanobacteria blooms, despite major reductions in phosphorus inputs, demonstrates the complexity of predicting the response of lakes undergoing multiple global stressors and management strategies. 

Primary Presenter: Adam Heathcote, Science Museum of Minnesota (adam.heathcote@gmail.com)

Authors:

Adam Heathcote, Science Museum of Minnesota, St. Croix Watershed Research Station  (aheathcote@smm.org)

Mark Edlund, Science Museum of Minnesota, St. Croix Watershed Research Station  (mbedlund@smm.org)

Shane Bowe, Red Lake Department of Natural Resources  (SBowe@redlakenation.org)

Kayla Bowe, Red Lake Department of Natural Resources  (Kayla.Bowe@redlakenation.org)

Cary Hernandez, Minnesota Pollution Control Agency  (cary.hernandez@state.mn.us)