Remotely sensed cyanobacterial intensity predicts likelihood of lake blooms and toxins across the contiguous U.S.

Cyanobacterial harmful algal blooms (CHABs) can produce toxins which impair freshwater ecosystems used for drinking water, recreation, and habitat for aquatic biota. With CHABs increasing in extent and intensity globally, water managers need information about how to prioritize lake monitoring. We combined the Cyanobacterial Assessment Network (CyAN) remote sensing data with the U.S. EPA National Lakes Assessments completed in 2007 and 2012 to predict the likelihood of measuring CHABs in lakes across the U.S. We use logistic regression modeling to relate the likelihood of lakes exceeding health recommendation thresholds associated with CHABs based on mean summer bloom intensity from CyAN. We then used the model to extrapolate the likelihood of exceeding CHABs thresholds to all lakes monitored via CyAN. We find that the interannual mean bloom intensity from CyAN can be used to estimate the relative risk of lakes exceeding CHABs health thresholds. Such information can help inform setting priorities for lake water monitoring in regional contexts.

Impact/Purpose

Cyanobacterial harmful algal blooms (CHABs) can produce toxins which impair freshwater ecosystems used for drinking water, recreation, and habitat for aquatic biota. With CHABs increasing in extent and intensity globally, water managers need information about how to prioritize lake monitoring. This presentation to the Oregon Lake Association meeting highlights an analysis from Pacific Ecological System Division scientists that combines data from the remote sensing Cyanobacteria Assessment Network (CyAN) and the National Lakes Assessments completed in 2007 and 2012 to predict the likelihood of CHABs. By developing models based on the subset of lakes that are captured in the CyAN data and those that are sampled in the NLAs, the likelihood of exceeding health thresholds associated with CHABs can be extrapolated to all lakes monitored via CyAN. The Oregon Lakes Association is a member-driven organization with wide cross-section of people including recreationists, property owners, public agencies, non-profit organizations, local lake associations, students, professors, and environmental consultants. This research is consistent with their mission to promote the understanding, protection, and thoughtful management of lake and watershed ecosystems in Oregon.

Citation

Handler, A., J. Compton, Ryan A Hill, AND S. Leibowitz. Remotely sensed cyanobacterial intensity predicts likelihood of lake blooms and toxins across the contiguous U.S. Oregon Lakes Association, NA, Oregon, October 28 - November 10, 2020.