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New Underwater Vehicles and 'Gliders' Helping NCCOS Scientists Better Explore HABs
NOAA marine scientists are exploring new automated ways to better understand the development and movement of harmful algal blooms, HABs, paving the way for providing coastal managers increased lead time to help reduce potential harmful impacts.
Using an emerging new breed of autonomous underwater vehicles or AUVs – what to the lay person may be better understood as programmable underwater robots – scientists from NOAA’s National Centers for Coastal Ocean Science, NCCOS, are optimistic they will be able to complement and go beyond data being derived from satellites, buoys, and towed instruments.
"We expect to be able to detect and track HABs with these AUVs in an effort to give early warning to coastal communities that red tides may be on their way," says marine scientist Gary Kirkpatrick, of the Mote Marine Laboratory in Sarasota, Fl.
"There are a variety of things various interests can do to mitigate the harmful impacts," Kirkpatrick continues, “and a few days advance warning is real helpful."
"You just can’t have people out on boats all the time looking for these early stages of blooms. But we can, conceivably, have AUVs out there almost all the time looking for them."
NCCOS scientist Patricia Tester, on the Beaufort, N.C., Center for Coastal Fisheries and Habitat Research, has been testing the "Ranger" AUV. She finds it particularly useful in shallow water estuaries and when several are used simultaneously to traverse along parallel tracks.
'Real-Time Information' for Resource Managers
Describing a March 2003 alpha test, Tester still expresses some amazement "with the total success of this first test run. The project was done on a shoestring budget, and was an ideal demonstration project that married engineering and biology, federal research and private industry." She’s hopeful about the potential for producing "very versatile products that would supply real-time information to managers of estuaries, river systems, aquaculture facilities, drinking water reservoirs, and near-shore areas."
The new-generation AUVs travel on their own power, are highly maneuverable, and can be outfitted with a variety of scientific instruments to take on-site – what scientists call in situ – measurements at locations the scientists pre-select. Complementing data from remote sensors such as satellites and buoys and research cruises, the AUVs provide a more thorough view of the ocean conditions, allowing improved forecasts of HAB development and movement.
A new class of winged AUVs, or gliders, share dynamics long associated with their airborne counterparts. Roughly six or seven feet long, they generally resemble torpedoes, with oversized fins. Kirkpatrick explains that they can operate a week or two at sea depending on the instrumentation payload they carry and whether those instruments are powered.
Picture the Glider's 'Saw-Tooth Pattern'
The glider, also referred to as the Slocum glider, has a small cylinder and piston that controls whether and how much water is pumped in, making the glider more or less dense in water so that it climbs or descends as needed.
"When it draws water in, it becomes heavier," Kirkpatrick says. "An altimeter tells it how far it is from the bottom, and when it gets to a predetermined depth, it pushes water out and glides forward and upward. Picture it as a saw-tooth pattern, Kirkpatrick says, adding that it produces "a very dense data set, sampling about every three seconds." The Slocum glider is effective to about 250 meters – about 820 feet – more than adequate to support its use in researching HABs off West Florida’s continental shelf, where some of the AUV research is under way.
Funded by NCCOS’s Center for Sponsored Coastal Ocean Research (CSCOR) Oceanography of Harmful Algal Blooms program, or ECOHAB, the Slocum glider research focuses on continuous monitoring of the Karenia brevis red tide organism. The study combines expert scientific competencies from Mote, Rutgers University, California Polytechnic State University, and Webb Research Corporation.
Flexibility, Size Keys in Estuarine Work
Speaking of her research using the Ranger AUV in shallow-water environments, Tester points out it eliminates the need for a large launch platform, and she says it can be programmed, based on geographical information system coordinates, to change its "behavior" on the fly. She envisions advances that will allow a set of Rangers operating in tandem to communicate with each other when they encounter a marine “area of interest” that may justify increased attention. Their flexibility and small size make them particularly effective in estuarine work, Tester says.
"The Rangers accurately detected and mapped the features we asked them to map," Tester says. "Everything worked perfectly, just as programmed and just as planned."
Costs, of course, are always a consideration. Both Tester and Kirkpatrick acknowledge that the AUVs are "not cheap," but they say they think the economics compare favorably considering the costs of staffing and operating research vessel time. Kirkpatrick says actual operation and maintenance costs generally involve battery changes, cleaning, and personnel time "keeping an eye on them and reviewing the data they are constantly sending back."
NO, 'Breve Busters'
Where do blooms start? How do they move? In what directions? How fast? How accurate can their movements be forecasted?
Those are among the many questions the NOAA scientists and their private sector colleagues are attempting to get better information on as their research proceeds. Another phase of that continuing effort will get under way this summer, with research cruises scheduled off the West Coast of Florida along with the AUVs. Those five-to-six day cruises, each involving a dozen or so scientists, are expected to take place in the vicinity of Tampa Bay and Charlotte Harbor. But if a bloom were to appear off Naples, the researchers are prepared to refocus their efforts there.
Taking a cue from the "Ghost Busters" movie, the NCCOS scientists are cautiously optimistic about their " Breve Buster" research on AUVs.
Their current thinking is that the research will open the way for new and improved methods of detecting – and mitigating – impacts of HABs. As that happens, coastal communities will be all the better equipped to avoid the adverse HAB impacts on local economies, tourism, and coastal resources generally.
