Slime on the Rise

Cyanobacteria harmful algal blooms (cyano HABs) are a common source of water contamination in America’s Great Lakes. Cyano HABs occur when algae grow rapidly, forming a layer of dense scum that is usually green in color and can mimic a dense green slime. Some blooms produce toxins that can contaminate drinking water, harm people and animals, and pose a severe nuisance to recreational and commercial boating and fishing.

Drinking water managers and environmental and health agencies operating in the Great Lakes region are always on the hunt for early-detection tools to add to their arsenal. The National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory, the Environmental Protection Agency (EPA), the Department of Natural Resources, and drinking water managers in the Great Lakes regularly monitor the Great Lakes for cyano HABs using sensors on the water and in the sky. Satellite imagery is one such tool these partners employ. Its ability to observe nearly everywhere, nearly all the time, is immensely helpful. However, cloud cover is satellite kryptonite — clouds can temporarily prevent satellite monitoring, which could cost precious time in detecting a developing cyano HAB.

With funding from the Great Lakes Restoration Initiative, the NOAA Great Lakes Environmental Research Laboratory has been employing another valuable tool to detect cyano HABs—hyperspectral technology. Lab personnel equip an airplane with a hyperspectral camera for weekly flights over the lakes. This camera measures many different wavelengths of light beyond those a typical satellite can observe. The hyperspectral camera also captures data beneath clouds where satellites are unable to collect measurements.

NOAA’s Great Lakes Environmental Research Laboratory flies a single-engine Cessna airplane over the Great Lakes during the cyanobacteria harmful algal bloom season. Positioned in the back of the airplane is a hyperspectral camera that is able to accurately capture surface cyanobacteria levels directly over drinking water intakes. The bigger image is looking westward into the Maumee River that feeds into Lake Erie and the smaller image is a true-color image of the same freighter taken from the hyperspectral camera.

“The Great Lakes, and cyanobacteria harmful algal blooms, still have many dynamics that are not understood,” said Andrea Vander Woude, a research physical scientist and remote sensing researcher with NOAA Great Lakes Environmental Research Laboratory. "This cutting-edge hyperspectral technology will take harmful algal bloom forecasting capabilities in the Great Lakes to the next level.”

The detail and high resolution of the camera’s imagery help scientists evaluate the types of algae groups within a bloom and determine whether they contain harmful toxins. These data will also advance research to develop predictions of bloom toxicity. Earlier and more accurate predictions will help municipal drinking water managers and other water users know when a cyano HAB might become a concern — both saving time and reducing human and animal suffering.