July 16, 2002

FORECASTING JELLYFISH IN CHESAPEAKE BAY

Before planning your next beach outing on Chesapeake Bay, you will of course check the weather forecast, and before long, you may be able to check the jellyfish forecast as well. A team of scientists at the National Oceanic and Atmospheric Administration and several universities has developed a prototype forecasting system that predicts the likelihood of sea nettles, a stinging jellyfish, in the bay. They report on their work in the July 30 issue of Eos, published by the American Geophysical Union.

The forecasting technique takes advantage of new technology and improved communication that allow continuous monitoring of environmental factors in the bay, the east coast's largest estuary. "Sea nettles [Chrysaora quinquecirrha] are ideal organisms for evaluating this approach," writes oceanographer Christopher W. Brown, lead author of the study, because their occurrence is closely related to salinity and sea-surface temperature, two variables that are already observed in near-real time. He hopes that once the forecasting model has been refined and validated, the same techniques can be extended to other noxious organisms, such as algal blooms, or red tides, that negatively affect tourism worldwide.

The economic effect of sea nettles is not limited to vacationers or weekenders who may shun Chesapeake Bay beaches to avoid painful allergic reactions from contact with their tentacles. Sea nettles are, Brown notes, voracious predators, devouring copepods (minute crustaceans), fish eggs and larvae, and comb jellies, thereby affecting the food web and thus, possibly, the abundance of fish in the bay. The adverse effect of sea nettles may be mitigated if their presence can be monitored and predicted in near real time, he says.

Already, NOAA is preparing "nowcasts," maps showing the current likelihood of sea nettles in Chesapeake Bay and its major tributaries, such as the Susquehanna and Potomac Rivers. These maps are updated every Friday and may be consulted on the web at http://coastwatch.noaa.gov/seanettles.

As the existing forecasting model is tested and refined, Brown and his colleagues will add to it other variables known to affect sea nettle concentrations, such as wind speed and depth of the water. Eventually, they hope to predict the effect of climate change on sea nettle concentrations, by analyzing the effect of that change on the specific variables relevant to the nettles. Extending the technique to other organisms will be more difficult, they note, because other factors, such as nutrient concentrations, would have to be taken into consideration, and those are not as easily monitored on a continuing basis.

The study is funded by grants from NOAA's Ocean Remote Sensing Program, Maryland Sea Grant Project Development, and the National Science Foundation.

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Contact:

Harvey Leifert
American Geophysical Union
202-777-7507
hleifert@agu.org

This text derived from http://www.agu.org/sci_soc/prrl/prrl0225.html

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