Predicting the Sensitivity of Boreal Lake Ecosystems to Climate Change

Expedition Date: August 26 – September 2, 2018

Field Team Members: Carl Tugend (CCI), Mark Edlund & Adam Heathcote (St Croix Watershed Research Station), Charles Umbanhowar (St Olaf College)

Expedition Funding Acknowledgement: National Park Service PMIS #160929

Expedition Report: 

Multiple lines of evidence suggest that wilderness boreal lakes are rapidly changing, with unprecedented appearances of potentially toxic cyanobacterial blooms, the disappearance of coldwater fishes, and significant shifts in algal communities. These changes have important implications for the aesthetic and habitat value of these lakes. A recent assessment of ecosystem stressors in the Great Lakes places the waters surrounding Isle Royale National Park at high risk to future climate change. Our past work suggests that the observed algal shifts in boreal lake ecosystems may be driven by climate change, although the sensitivity and response appears to differ depending on lake size, depth, and other characteristics. We propose that the sensitivity of lakes to climate change varies along a gradient of lake thermal structure and can be predicted using key physical lake parameters. We are using a combination of lake monitoring, thermal modeling, and sediment records of algal remains to characterize the sensitivity (long-term ecological change) of eight wilderness boreal lakes of differing size on Isle Royale to climate change. This expedition focused on coring two lakes, Sargent and Richie, to obtain sediment records spanning back 2,000 years.