Real-time lake data advances ecology research

Bobbing over the 100-foot depths of northern Wisconsin’s Trout Lake, a technology-stocked buoy is helping scientists track the vital signs of major ecological change.

Trout Lake Research Station, the northern outpost of lake researchers at the university, added the unique remote sensing buoy this summer to its arsenal of water research tools. The $85,000 monitoring buoy is putting out a steady stream of data on the water and the atmosphere, which is feeding the station’s long-term research efforts.

Among the sophisticated gadgets on the buoy is a “vertical profiler,” a unit that can probe the deepest point in Trout Lake — 107 feet – and provide all sorts of water quality measures along the way. The profiler is attached to a cable and controls its buoyancy like a submarine.

From below, the buoy measures water temperature, clarity, mineral content, dissolved gases, pH, and chlorophyll levels. From above, it tracks wind, barometric pressure, relative humidity, light and air temperature.

Collectively, the information is the raw material for the station’s Long-Term Ecological Research project, which is helping track global warming, pollution or landscape changes that take ages to manifest themselves.

Trout Lake, six other northwoods lakes and four Madison-area lakes are part of the National Science Foundation’s LTER program, which encompasses 24 field stations around North America. The landscapes include everything from Arctic tundra to arid desert.

Paul Hanson, a scientist with UW–Madison’s limnology laboratory, introduced the technology to colleagues at an all-scientists meeting of LTER in August. He says the technology should be a boon to the program’s goals of tracking subtle ecological changes.

Collecting baseline information on water quality is a core activity at Trout Lake, and this remote sensing buoy does it without anyone getting their feet wet. The buoy is equipped with a small computer and Internet connection that transfers all the information in real time to a web site.

“The communication system we’re using is called spread-spectrum radio, a recently declassified military technology,” Hanson says. “It’s basically unencodable because the signal hops across different frequencies.”

The buoy has three flat legs containing solar panels that run all the equipment. The station is moored to one spot in the lake and surrounded by bright orange buoys.

“Our ultimate goal is to take the Internet right into the field, and not only collect information but control the device via Internet connection,” Hanson says.

Apprise Technologies, a company out of Duluth, Minn., built the standard buoy system used primarily in large reservoirs and the Great Lakes. Hanson says researchers are still uncertain about whether to keep the buoy in business through the long northwoods winter. The data would be valuable, he says, but the warranty doesn’t cover ice damage.