Thursday, April 30, 2015

Algae Blooms to be Monitored from Space

Earlier this month the U.S. Geological Survey (USGS), the U.S. Environmental Protection Agency (EPA), NOAA and NASA announced that they are jointly is developing an early warning system using historical and current satellite data to detect algal blooms. The $3.6 million project intends to create a reliable, standard method for identifying cyanobacteria blooms in U.S. freshwater lakes and reservoirs using water color satellite data. “Algal blooms pose an expensive, unpredictable public health threat that can affect millions of people,” said Sarah Ryker, USGS Deputy Associate Director for Climate and Land Use Change. “By using satellite-based science instruments to assess conditions in water and on adjacent land, we hope to improve detection of these blooms and to better understand the conditions under which they occur.”

NOAA and NASA pioneered the use of satellite data to monitor and forecast harmful algal blooms especially in the Gulf of Mexico and Great Lakes. Satellites allow for more frequent and continual observations over broader areas than water sampling and could provide and potentially an early warning of the formation of a toxic algae bloom. The Landsat satellite series, a joint effort of USGS and NASA, has provided a continuous recording of land use and land cover conditions since 1972. The latest satellite, Landsat 8, has demonstrated promising new capabilities for water quality assessment.

Toxic algae blooms also called dead zones form in summers when higher temperatures reduce the oxygen holding capacity of the water, the air is still and especially in years of heavy rains that carry excess nutrient pollution from cities and farms. The excess nutrient pollution combined with mild weather encourages the explosive growth of algae fed by excessive nutrient pollution. The dead zones in the 1970’s were caused by the release of phosphorus in what we would today consider partially treated sewage being released by waste water treatment plants. Stronger regulations on waste water treatment plants under the Clean Water Act seemed to alleviate that problem to a large extent. However, the ecology of newer toxic algae blooms capable of affecting human health began to appear in this century.

Only certain species of blue-green algae form the toxin, for reasons that aren't fully understood. Toxic bacteria were not a problem until the 21st century, though algae blooms have been a problem on Lake Erie, the Gulf of Mexico, the Chesapeake Bay and other areas for over half a century. Microcystine or cyanobacteria is a toxin produced by microcystis, a type of blue-green algae that spreads in the summer algae bloom. These dead zone toxic algae blooms had almost disappeared on the Great Lakes by the end of the 20th century, but there has been a recurrence with some of the worst algae blooms seen in the Great Lakes occurring in the last six to eight years. EPA Administrator Gina McCarthy attributes this to climate change.

Last August the water supply for Toledo, Ohio tested positive for microcystine. A “Do Not Drink” order was issued for the city and the residents were without drinkable tap water for three days. On day three the drinking water from Toledo’s Collins Park Water Treatment Plant was declared safe to drink and life returned to normal in Toledo, Ohio, but is the new normal safe drinking water only most of the time. The current study project is intended to broaden our understanding of the formation of toxic algae blooms. EPA researchers are working to develop mobile apps for local communities to respond quickly to real-time water quality issues.

The joint agency project also includes a research component to improve our understanding of the environmental causes and health impacts of cyanobacteria and phytoplankton blooms across the United States. Blooms in lakes and estuaries are produced when aquatic plants receive excess nutrients under suitable environmental conditions. Various land uses, such as urbanization and agricultural practices, change the amount of nutrients and sediment delivered in watersheds, which can influence cyanobacterial growth.

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