KEY WEST, Fla. – Florida scientists trying to get a handle on the health and condition of the world’s fragile coral reefs have turned to sophisticated tools – including satellite technology – that are best-known for their use in tracking terrorists and hurricanes.

Satellite data and images -available to researchers from a variety of government sources – from the National Oceanic and Atmospheric Administration to NASA – are providing complex pictures of everything from ocean temperature to coral cover.

Satellites applied to public scientific research can zero in on areas as small as one meter, though most are able to zoom into images between one kilometer to 30 meters in size.

In recent years, the techniques have had a profound influence on the scope and ambition of traditional marine research, scientists say.

“It’s made us think regionally, and it’s allowed us to identify things we could never separate,” said Robert Ginsburg, a University of Miami geologist who studies coral reef health in the western Caribbean. “We’ve mapped areas of specific characteristics, or habitats, like neighborhoods. And we can map these neighborhoods from space.”

At the forefront of the new techniques are Frank E. Muller-Karger and Chuanmin Hu, two researchers at the University of South Florida’s Institute for Marine Remote Sensing.

“We are at the cutting edge,” Muller-Karger says.

The men use a method that looks at slight color gradations of ocean water obtained from satellite images to extrapolate the water’s health. Each gradient of color is given a specific marking and a property that corresponds to different conditions.

The satellites are also applied to provide information – and pictures – of water glow, suspended sediments, water depth and seagrass cover.

The images aren’t always perfect. They can be susceptible to streaking across parts of the sensor, and smoke and cloud cover can reduce visibility or contaminate colors.

Some of the satellite data Hu and Muller-Karger sift through comes from NASA’s Terra, Acqua, and LANDSAT – which employ special sensors to measure water color and temperature, cloud cover and atmospheric properties – as well as one privately owned satellite.

Five NOAA satellites take stock of properties like seawater temperature.

Satellites used solely by intelligence agencies generally have less sweep but are believed to be able to capture objects that are inches in size.

NASA is helping to underwrite one of the duo’s projects that aims to apply satellite imagery to determine how Keys’ coral reefs have changed over the past quarter-century.

“We want to see if there is a spatial relationship between where changes have been seen on the reef and changes that have occurred on land,” Muller-Karger said.

Another project has teamed the men with NOAA to square on-the-water snapshots of ocean color with images received and interpreted from satellites at the exact same moment.

NOAA scientists on research vessels are equipped with spectrometers, which look like video cameras.

They are asked to take pictures of water in particular places and times when a specific satellite is flying over recording images. Then the results are compared.

Such techniques allow NOAA to immediately anticipate and respond to problems like red tide or other environmental crises that could threaten protected coral.

“Ten years ago, we didn’t have the luxury of up-to-the-minute reporting from space,” said Libby Johns, a researcher at NOAA’s Atlantic Oceanographic & Meteorological Lab. “These guys can send us images while we are out on a research trip in real time.”

Hu and Muller-Karger’s techniques marry physics, computer science, biology, geology, and oceanography.

They’ve had to write software for use in crunching satellite data and were forced to devise new theories to explain the physics of light, water and atmosphere.

Each day, they pore over satellite data received through two antennas on the roof of their St. Petersburg, Fla., research building, process it, and then place it on their website so the public can view it.

They’re constantly refining techniques.

“One of the things we would like to do is develop tools that look at things that happen over a large area over a large period of time and look at the frequency,” Muller-Karger said. “It doesn’t really serve a purpose to look at something once.”

Though Hu is well-known among reef researchers, most of his funding comes from a project to study the color and climate change of large rivers like the Amazon and Mississippi. “This is a side project for us,” Hu says of the coral reef studies.

Still, when scientists and public officials heard about an alarming envelope of black water that migrated a few years ago from Florida’s southwest coast to the Gulf of Mexico off the Keys, they turned to Hu and Muller-Karger for some answers.

The researchers were able to plot the flow of the water and determined that it was likely the result of fresh water from rivers in the Everglades area flowing west and mixing with plants growing in the Gulf to produce a scary-looking hue.

Hu and Muller-Karger are hoping for more real-world use of their data. Marine managers, they say, haven’t had the money to regularly incorporate new technology.

“Scientists are using this information, but the managers who regulate the fisheries and the sanctuaries aren’t,” Muller-Karger said. “We want our research to be useful.”



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