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USF scientists use NASA satellites to detect "glow" of natural bio-threats TAMPA, Fla. (Aug. 31, 2004) - Oceanographers at the University of South Florida's College of Marine Science are using remote-sensing fluorescence data gathered from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and other instruments aboard both NASA's Terra Aqua satellites to differentiate between algae and plumes of dark-colored runoff from river and wetlands, sometimes causing "blackwater." Armed with such information, researchers could notify regional environmental managers who can obtain field samples in time to warn fisherman and swimmers about developing cases of red tide, which occur every year off Florida, causing fish kills, coral stress and mortality as well as skin and respiratory problems in humans. The USF scientists were able to detect and measure phytoplankton bloom fluorescence - invisible to the human eye in the Gulf of Mexico when instruments captured the red glow from the plant's chlorophyll. "Without remote sensing data of this nature - namely looking at Earth with a camera very sensitive to the red color where plants fluoresce in daylight - it is impossible to differentiate plankton blooms from plumes of dark river runoff that may contain little phytoplankton," said Frank Muller-Karger, a professor in the College of Marine Science. River runoff of fertilizers containing nitrogen and phosphorus cause blooms of marine algae, or phytoplankton. When highly concentrated, the blooms make the water appear black. As phytoplankton die and sink to the ocean bottom they are eaten by bacteria. The hungry bacteria also deplete oxygen in the water, leading to fish kills. Prolonged "black water" patches cause water quality degradation and may cause coral death. Because dissolved organic matter originating in rivers can also absorb similar amounts of blue light as plants, satellites measuring ocean color alone cannot be used to confirm that such dark patches contain phytoplankton blooms. However, if the water emits red light this clearly identifies the presence of large quantities of phytoplankton, as they glow red under sunlight. With those measurements, scientists are able to calculate the amount of nutrients needed to grow a given amount of plankton. The ability to detect glowing phytoplankton-rich areas of water via remote-sensing satellite helps researchers identify where phytoplankton are plentiful and helps predict and monitor red tide and blackwater events. In their study, researchers used NASA satellites to study the nature and origin of a dark plume event in the fall of 2003 near Charlotte Harbor, off the south Florida coast. "Our study traces the black water patches near the Florida Keys to some 200 kilometers (124 miles) upstream," USF researcher Chuanmin Hu said. "These results suggest the delicate Florida Keys ecosystem is connected to what happens on land and in the Peace and Caloosahatchee rivers as they drain into the Gulf. Extreme climate conditions, such as abnormally high spring and summer rainfall in 2003, may accelerate such connections." To complete their study, Hu and Muller-Karger used satellite ocean color data from MODIS and Sea-viewing Wide Field-ofview Sensor (SeaWiFS), and wind data from NASA's QuikSCAT satellite. The U.S. Geological Survey, the National Oceanic and Atmospheric Administration, Florida's Fish and Wildlife Research Institute, and other organizations provided rain, river discharge and field survey information. "The integration of multiple data sources provides a powerful means for monitoring the environmental health of the coastal ocean," explained Hu. Their study appeared in the American Geophysical Union's Geophysical Research Letters. Gabriel Vargo and Merrie Beth Neely from University of South Florida and Elizabeth Johns from NOAA's Atlantic Oceanographic and Meteorological Laboratory are co-authors. For more information and images visit: http://www.gsfc.nasa.gov/topstory/2004/0826planktonglow.html STORY SOURCES: Frank Muller-Karger (727) 553-3335 Chuanmin Hu (727) 553-3987 Media Contact: Randolph Fillmore (813) 974-8476 - USF -