You are here:
Satellites predict lakes at risk from cyanobacteria and microcystin toxins.
Citation:
Handler, A., J. Compton, Ryan A Hill, S. Leibowitz, AND B. Schaeffer. Satellites predict lakes at risk from cyanobacteria and microcystin toxins. North American Lake Management Symposium, Oklahoma City, OK, November 15 - 18, 2021.
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 for the North American Lake Management Symposium highlights the results of national modeling of lake CHABs risk by combining data from the Cyanobacteria Assessment Network remote sensing data on CHABS and USEPA’s National Lakes Assessment field algal data. These two components of the CyAN project illustrate EPA work that strives to address the needs of water resource managers as it relates to setting monitoring priorities for CHABs. The symposium is attended by HAB researchers and lake water resource managers. Their knowledge and feedback about this analysis is invaluable to creating a product that helps inform about lake CHABs risk.
Description:
Cyanobacterial harmful algal blooms (HABs) can produce toxins that impair freshwater ecosystems used for drinking water, recreation, and habitat for aquatic biota. With HABs increasing in extent and intensity globally, water managers need information about how to prioritize lake monitoring. Remote sensing is a promising monitoring tool, but a challenge is connecting satellite data with field bloom conditions across a broad spatial extent. We combined Cyanobacteria Assessment Network satellite data of lakes between 2008 and 2011 with HAB field data from the USEPA’s National Lakes Assessments conducted in 2007 and 2012. There were 210 lakes with both satellite data and were surveyed for microcystin toxin, cyanobacteria, and chlorophyll a. We calculated the mean summer bloom magnitude for each satellite-resolved lake and used logistic regression to estimate the likelihood of each lake exceeding the human health risk thresholds of 1.0 µg/L microcystin, 100,000 cells/mL cyanobacteria, or 50 µg/L chlorophyll a. In all cases, a unit increase in the lake bloom magnitude was associated with a 15-40% likelihood increase in exceeding HAB thresholds. We used the modeled relationships to predict the likelihood of threshold exceedance for all 2,192 lakes monitored by satellite. Among these lakes, 37-69 were highly likely (>75% likelihood) to exceed the thresholds. This approach leverages existing national scale data to identify lakes that are at risk for exceeding bloom thresholds that is both geographically comprehensive and grounded in field data. Such analyses are critical for connecting satellite information with field conditions to aid setting monitoring priorities for lake management.