Mote Marine Laboratory

What’s So Cool About Red Tide?

By: David Donald

Mote is setting up a new high-tech tracking system to seek out harmful algal blooms

Red tides that kill fish and marine mammals, cause tourism-dependant businesses to lose money and make humans cough, sneeze or have trouble breathing aren’t very cool.

But a new detection system in the Gulf of Mexico that could give early warning of an approaching red tide bloom is.

In fact, it’s SO COOL — or the Sarasota Operations Coastal Oceans Observation Lab. This Sarasota-based red tide detection center developed by Mote scientists will use information from an arsenal of satellites, autonomous underwater vehicles (AUVs), planes, boats and buoys to monitor red tide in an effort to provide an early warning of red tide events along the Florida coast.

“I envision a regional system that is like the weather system,” said Dr. Gary Kirkpatrick, manager of the Phytoplankton Ecology Program in Mote’s Center for Ecotoxicology.

Researchers at Mote are working to develop and implement the high-tech system designed to detect Karenia brevis, a naturally occurring microscopic algae that’s been documented along the Florida coast for hundreds of years. Research partners are Rutgers University, California Polytechnic State University, the University of South Florida, the Florida Fish and Wildlife Research Institute and the National Oceanic and Atmospheric Administration.

K. brevis is a species of phytoplankton with chlorophyll molecules. When it multiplies as it moves in some warm, nutrient-abundant coastal waters it can bloom, creating a red tide. The bigger a bloom grows, the better chances it has of wreaking havoc in Florida’s coastal communities. K. brevis can release a neurotoxin into the air that causes itchy throats and sneezing in people. It also kills marine mammals, fish and contaminates shellfish beds. Hotels, recreational and commercial fishing, restaurants and coastal aquaculture farms are the hardest hit by red tide.

An early warning system could help these industries prepare for red tides and help people with asthma or other chronic lung diseases know when to stay away from beaches. Portions of the system are already in place.

NOAA uses satellites to monitor the oceans for algal blooms by seeking areas that have a high concentration of chlorophyll. Chlorophyll, the green pigment in plants, absorbs sunlight and shows up in satellite imagery on a color-coded map. Red represents a high concentration of chlorophyll — which means an algae outbreak.

There are many different kinds of algae. Not all of them are red tide, and not all of them are harmful to humans, fish and marine mammals. So using satellite imagery is just one part of a forecasting system. The other parts of the system come from the groundtruthing, from being on the water taking a close look at what’s really going on in the ocean.

One way to do that is by sending out boats with people in them to take water samples and then put those samples under a microscope to see if there is K. brevis present. But there are only so many people and boats available and only so many places they can test before funding and manpower limitations kick in. Mote and its partners are testing a new way to search for red tide — one that can be run continuously and doesn’t rely on costly manpower.

Enter AUVs and Brevebusters

Autonomous underwater vehicles are preprogrammed to operate without human intervention. One type, the Slocum Glider, looks like a yellow torpedo with wings and is designed to dive and climb through the water column in a zigzag pattern using ballast to move up or down and forward. AUVs can remain at sea for 30 days, communicating with scientists and computers on land by high frequency radio transmissions that are sent to satellites when the glider surfaces. Another AUV with similar capabilities is the REMUS, Remote Environmental Monitoring UnitS. Rather than gliding through the water column, the REMUS has a propeller and rudder that helps it maneuver on a pre-programmed path.

Both types of AUVs are equipped with devices to measure water temperature and salinity. But the main payload is the red tide detector — the BreveBuster — invented at Mote by Kirkpatrick and engineered by Jim Hillier, the instrument specialist for the Phytoplankton Ecology Program. “The gliders are platforms to carry our instruments,” said Kirkpatrick. “They are intelligent and capable, to the point where we don’t have to have people on ships all the time to look for red tide.”

So far, seven BreveBusters have been deployed on AUVs and buoys in Tampa Bay and the Gulf of Mexico, including one that had been on a channel marker in Boca Grande Pass until Hurricane Charley tore through the area. The cost to build the $15,000 instruments was paid for by National Science Foundation and NOAA grants.

“The instrument takes in a sample of water containing all the particles that are in the water and they flow those particles through a very small diameter quartz tube,” said Kirkpatrick. “As those particles in the water are flowing down the tube, we shine a light down the length of it, and then we look at the light spectrum that comes out the other end. From measurements like that we can determine what the light-absorbing characteristics of the particles are. And we know what the light absorbing characteristics of red tide is and we can compare the two.”

Rutgers and CalPoly have been bringing their AUVs to Mote for field tests in the Gulf, making instrument refinements and solving software problems and Mote plans to have its own AUV in place in January 2005. “There are a lot of trials to make this system work,” said Mark Moline, professor of marine science at California Polytechnic University. “This collaboration among Mote, Rutgers, and Polytechnic is very important.”

The new technology expands the science, said Dr. Richard Pierce, director of Mote’s Center for Ecotoxicology. “We must have the ability to monitor along the bottom as well as the surface, and that’s what the advantage of the AUV is. It provides surface to bottom surveillance, whereas satellite imagery can only see the surface.”

The BreveBuster-equipped AUVs will be an important part of a new NOAA red tide forecasting system that started operating in October. System forecasters rely on satellite imagery and information about coastal air and water currents to make a prediction about a potential red tide bloom. When a possible bloom is identified, an AUV could be sent out to make a positive identification.

So, too, could the satellites be used to help direct an AUV mission, Kirkpatrick said. “They really are complementary technologies,” he said. “You’ve got information coming in (to the SO COOL) from satellites, from CODAR, which measures surface currents, from ships and buoys that have Brevebusters. The pieces come into the lab and are fit together, and you can use that information to define where the AUV mission goes.”

That’s the groundtruthing.

During recent field tests, a glider equipped with a BreveBuster swam through an area detected by satellite as a suspicious bloom and determined that the bloom was not red tide. In another test, a glider swam thorough a bloom around St. Petersburg and found red tide. That information was then combined with readings on winds and water currents and satellite imagery to predict where the red tide would go next.

“Mote working on these torpedoes is great,” said Daniel Leonard, owner of Bull Bay Clam Farms in Englewood, Fla. “I need that. If I know ahead of time (about a red tide) it gives me early warning so I can do something with my clams.”

Leonard recalls one red tide that devastated his harvest. A warning would have allowed him to move his product around the state. “When I first started, red tide was awful,” said Leonard. “Now they are starting to pinpoint it a little better.”

Learn more about: Red Tide

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