NASA Enlists Satellites To Watch for Harmful Algal Blooms

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In August 2014, city officials in Toledo, Ohio warned 400,000 residents not to drink, cook with or bathe in the city’s tap water for three days due to an algal bloom in Lake Erie that tainted water flowing into the city treatment plant. The harmful algal bloom, caused by excessive levels of nutrients including phosphorous in Lake Erie’s warm shallow water, produced green slime on the water’s surface and a type of cyanobacteria dangerous to people and animals.

“There are currently insufficient resources to monitor all of the nation’s lakes and reservoirs for harmful algal blooms on the ground.”

To identify other harmful algal blooms in freshwater ecosystems in the continental United States, NASA, the National Oceanic and Atmospheric Administration, the Environmental Protection Agency and U.S. Geological Survey are beginning a five-year $3.6 million research campaign that relies on space-based sensors originally designed to detect variations in ocean color. Researchers want to use the sensors to find harmful algal blooms in lakes, estuaries, reservoirs and other freshwater bodies because it is difficult and expensive to gather that information from the ground.

“There are currently insufficient resources to monitor all of the nation’s lakes and reservoirs for harmful algal blooms on the ground,” said Keith Loftin, lead USGS principal investigator for the project. “Remotely sensed data provides a perspective that allows us to capture occurrence, persistence and harmful algal bloom movement through time while covering maximum area.”

Once satellites spot algal blooms that could pose a danger to nearby communities, agencies can investigate those sites using ground-based resources and “hopefully provide adequate warning for public health protection,” Loftin added.

The Operational Land Imager (OLI) on the Landsat 8 satellite captured this view of an algae bloom in the west end of Lake Erie last August. Credit: NASA Earth Observatory
The Operational Land Imager (OLI) on the Landsat 8 satellite captured this view of an algae bloom in the west end of Lake Erie last August. Credit: NASA Earth Observatory

Researchers plan to use data drawn from multiple spacecraft, including: the European Space Agency’s Envisat environmental satellite’s Medium Resolution Imaging Spectrometer (MERIS), which functioned from 2002 until 2012; the NASA-USGS Landsat 8 medium resolution Earth observation satellite; the Moderate Resolution Imaging Spectroradiometer on NASA’s Aqua Earth observing satellite; and the Ocean and Land Color Instrument, which is scheduled to launch later this year on ESA’s Sentinel-3 mission.

ESA’s ocean color instruments are uniquely suited to this effort because they provide spatial resolution of approximately 300 meters, which is high enough to identify algal blooms within lakes. MERIS also has spectral advantages over other sensors. For example, it observes light with a wavelength of around 709 nanometers, which can indicate high chlorophyll concentrations associated with algal blooms, said Paula Bontempi, manager of the ocean biology and biogeochemistry program at NASA Headquarters.

The new campaign is rooted in work NOAA oceanographer Richard Stumpf started in 2009 when he began using ocean color sensors to identify harmful algal blooms in Lake Erie. Based on that research, NOAA produces bulletins to inform everyone from charter boat captains to water treatment plant managers when and where harmful algal blooms are developing.

Through the national campaign, the agencies involved intend to establish a uniform approach to applying that type of satellite data to the task of identifying algal blooms in freshwater and to devise ways to disseminate that information in the form of bulletins and public health advisories, said Stump, one of the project’s principal investigators, who leads NOAA’s contribution to the initiative.

The EPA is developing tools and a mobile application people will be able to use to determine whether nearby lakes are safe for swimming or fishing. “Everybody is familiar with temperature maps,” Blake Schaeffer, EPA’s lead investigator on the project. “They know when it is going to rain and can make their plans based on that. We want that same technical capability for water.”

The EPA is beginning to test a mobile smartphone application it developed for the Android operating system. “We are hoping within the coming year to release it on the Google Play Store so the public could access it,” Schaeffer said.

Initially, researchers plan to focus on California, Florida, Ohio and New England states. “We’ll be building this capability over the five years of the project,” Schaeffer said. “By the end of the project, we hope to provide continental United States coverage.”

One of the most unusual aspects of the project is its extensive interagency collaboration. “In NASA Earth Science, we sometimes get partners working together on a basic or an applied research proposal, but often it’s hard to get research and operational partners to talk to each other,” Bontempi said. “I was floored by this effort, because all the groups have talked to each other and are ready to execute all the basic and applied research. They have a real shot at achieving their operational objective, which is exciting.”

Each agency has a role to play in the initiative. NASA, the primary funding agency for the project, plans to develop and validate the satellite products used to identify harmful algal blooms. USGS plans to provide processed Landsat imagery and assist interagency efforts to evaluate existing data on water quality. NOAA officials plan to share the expertise researchers have developed while monitoring harmful algal blooms in Lake Erie. The EPA, meanwhile, will be exploring ways to apply the research to bolster its effort to monitor and protect the environment and people living and working near coastal and inland bodies of water, Schaeffer said.

The multiagency campaign began to take shape during discussions in which Schaeffer and Stumpf talked about the various skills NOAA, EPA, USGS and NASA could contribute to harmful algal bloom monitoring. “We realized if we really started leveraging all of our skills together, we could come out with a much better effort and develop capabilities for monitoring harmful algal blooms that have never been seen before,” Schaeffer said.