Remote Sensing Provides a National View of Cyanobacteria Blooms

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Four Federal agencies, including the U.S. Geological Survey (USGS), are collaborating to transform satellite data into information managers can use to protect ecological and human health from freshwater contaminated by harmful algal blooms.

The U.S. Environmental Protection Agency (EPA), National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and the USGS are collaborating to develop a method to detect and measure cyanobacteria blooms in freshwater systems using satellite data in order to support the environmental management and public use of U.S. lakes and reservoirs.

Satellite Image Showing Estimated Cyanobacteria Concentrations

Two aerial images that demonstrate satellite-derived cyanobacteria concentrations in surface waters from an area in Florida. The top image is true-color photograph, and the bottom image is from the Medium Resolution Imaging Spectrometer (MERIS) sensor on the Envisat satellite, taken October 1, 2011. Data from the sensor lets scientists assign quantitative values for cyanobacteria concentrations, which are represented using a color scale ranging from blue (low concentrations) to red (high concentrations).

(Credit: Richard P. Stumpf, U.S. Geological Survey. Public domain.)

Cyanobacteria are a genetically diverse group of photosynthetic microorganisms (formerly known as blue-green algae) that occupy a broad range of habitats on land and water all over the world. Under certain environmental conditions (including excessive nutrients), cyanobacteria rapidly multiply to create a bloom that is sometimes referred to as a cyanobacterial harmful algal bloom (cyanoHAB). Some cyanobacteria produce toxins that can kill wildlife and domestic animals and cause illness or death in humans through exposure to contaminated freshwater or by the consumption of contaminated drinking water, fish, or shellfish. CyanoHABs are a worldwide environmental health problem that poses an expensive, unpredictable public health threat that can affect millions of people. In the United States, the cost of freshwater degraded by harmful algal blooms is estimated to be at least $64 million annually. In August 2014, officials in Toledo, Ohio, banned the use of drinking water supplied to more than 400,000 residents after it was contaminated by an algal bloom in Lake Erie.

CyanoHABs are a product of a complex set of natural and anthropogenic influences that make it challenging to provide early warning for public health protection and to minimize socioeconomic impact. Rapid detection of potentially harmful blooms is essential to protect humans and animals from exposure. Development of a scientifically robust, systematic identification of CyanoHAB events is key to achieving an early-warning capability and to focus field resources more efficiently.

EPA, NASA, NOAA, and USGS are approaching this environmental health issue using a combination of field level measurements and remotely sensed satellite data to assess cyanoHABs. Remotely sensed satellite data are currently available to scientists but are not consistently processed or produced in formats that help State and local environmental and water quality managers. Through this project, satellite data on harmful algal blooms developed by the partner agencies will be enhanced by coupling satellite data with field measurements of cyanotoxins and pigments associated with cyanobacteria that can be translated to cyanobacteria abundance. The combination of field measurements and remotely sensed data allows for the development of nationally consistent, physically based models that can be converted to a format that stakeholders can use through mobile devices and web portals. Satellite remote sensing tools may enable policy makers and environmental managers to develop early-warning indicators of cyanobacteria blooms at the local scale while maintaining continuous national coverage.

This research was funded by the USGS Ecosystems Mission Area’s Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology) as well as the NASA Ocean Biology and Biogeochemistry Program (14-SMDUNSOL14-0001), EPA and NOAA.