Volume 16, Number 2 • March-April 1998

Buoys Track the Bay

By Jack Greer

Think of the Bay as a large lava lamp say scientists involved in the high-tech monitoring of the Chesapeake Bay. "We have known that stratified waters tilt from east to west in the Bay," notes researcher Bill Boicourt of the University of Maryland Center for Environmental Science (UMCES). "But the dynamic is not a simple one." The picture, captured by Scanfish, a towed electronic "wing," is indeed that of a lava lamp-like wavy pattern, what Boicourt calls an "internal wave." These waves are created as lower salinity water flowing from the Bay’s rivers mixes with high salinity water from the sea.

This picture of the Bay’s internal currents – a kind of estuarine equivalent to the medical system’s MRI – has been made possible by advances in electronic data gathering. In addition to the towed wing (see "A High Tech Fish," Maryland Marine Notes, January-February 1996), scientists have used scanners from aircraft (ODAS) and, now, from satellites (SeaWiFS). The backbone of this high tech monitoring of the Bay is a buoy system known as CBOS, the Chesapeake Bay Observing System.

Unlike towed instruments and aircraft overflights, or even research vessels, buoys can remain on station day and night, week after week, month after month, gathering basic data, such as salinity, temperature, wind speed and oxygen levels. Just as a physician can tell much about a patient by monitoring blood pressure, heart rate and body temperature, scientists can track the Bay’s vital signs to determine its changing character.

This is a particularly crucial time to track the Bay. According to Walter Boynton, also of UMCES, "For the first time since John Smith showed up, nitrogen levels are actually going down in the Patuxent River." That trend downward results from a concerted effort to lower inputs of nutrients into the Bay, an expensive and expansive effort that has set as its goal a 40 percent reduction by the year 2000.

To know how the Bay is responding to such efforts, these scientists say, we need to take its pulse often and in different places.

"Imagine if the Dow Jones only reported stock prices once a month," Boynton asks. "People would go nuts." He compares this to changes in the Bay, where algae and other organisms may have life cycles on the order of two days or two weeks. A monthly measurement might easily miss a bloom or other event.

As Grant Gross, head of the Chesapeake Research Consortium, and others point out, changes in the Bay are often driven by "events." Some events, such as the 1972 storm Agnes, gain wide attention, but many other events – sudden squalls, sustained winds that drive water out of the Bay, rapid temperature shifts – may go largely unnoticed. It is often these events which influence the movement of the Bay’s "internal waves," shifting poorly oxygenated bottom waters upward, for example, and mixing warmer and cooler waters.

Conventional monitoring methods may well miss these key events, but the CBOS array of buoys can capture them, since they are constantly on station. At present there are four CBOS buoys, including a "rover" buoy deployed to target specific areas such as the Patuxent River, at specific times. The original aim has been to have eight CBOS buoys stationed up and down the Bay, though at $60 to $70 thousand the system remains an expensive proposition.

"We need partnerships," says Boicourt, who encourages other researchers to participate. Federal agencies will be key partners in the success of the effort, including the National Oceanic and Atmospheric Administration, the U.S. Coast Guard, and the Department of Defense, to name a few.

To help people access the data, Lowell Bahner from the U.S. EPA and others are working to link web sites, search engines and databases. According to Bahner, users will eventually be able both to query lists of information and to search for specific details from databases in a single stroke. Such data and information will not be held in at one large source, but will be distributed among a number of sources, each of which will maintain their own systems.

Of course consistency will be key, says Bahner, as will understandable methods of presenting the data to a wide range of users.

"We need to develop a set of indices," said Boicourt, so users can easily track specific trends in the Bay. "Let’s face it," he added, "Americans love to keep score."

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