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Fall 1998

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New Wave Oceanography
by Dawn T. Pick

Off-shore oil spills. Nuclear waste contamination. Sewage runoff. The problems threatening the world's oceans are so widespread that the United Nations has declared 1998 the Year of the Ocean.

It's no wonder that scientists are searching for a more detailed understanding of marine ecosystems.

"Historically, biologists and physical oceanographers have done their research independently with little collaboration," said Changsheng Chen, a UGA marine science professor.

"If you want to understand the [marine] environment, you need to understand the dynamics of ocean water movements," Chen said. "Marine life can be carried from one region to another by currents, so we need a good model to predict how the different physical processes affect the biological ones."

Chen, a physical oceanographer, has devoted his career to learning about the interaction between the physical and the biological processes of the sea. He and a team of other UGA scientists have devised a system for mathematical modeling of biological and physical ocean activity in offshore areas. This system gives scientists a better understanding of coastal ecosystems such as estuaries, where rivers empty into the sea.

The model integrates both physical and biological processes and simulates each component's role in a marine ecosystem. It also may prove crucial in helping policy-makers protect coastal areas from man-made ecological disasters like overdeveloping the coast or overfishing the oceans.

Chen already has applied the model to the Jiaozhou Bay on the East China Sea coast, a main source of seafood for the Chinese. Funded by the National Oceanic and Atmospheric Administration (NOAA) through the Georgia Sea Grant College Program, the study examines the effects of pollution on an ocean coast region and its marine life.

"The Jiaozhou Bay is very similar to our Georgia coast system. They both have larger tides, intertidal zones and substantial freshwater discharge from nearby rivers," said Chen, who is collaborating with several Chinese scientists on the study as well as developing a proposal for a future U.S.-China Cooperative Modeling Laboratory in Beijing.

A major difference, Chen said, is that, unlike Georgia's coast, the East China Sea coast has become seriously polluted by industries and overdevelopment.

Because of the similarities between the two areas, the model for the Chinese bay can be compared to his model of the Georgia coast, Chen said. Both models simulate physical variables such as the tide, tidal mixing, wind, temperature, sunlight and freshwater output of rivers. They also include studies of biological factors: phytoplankton, zooplankton and nutrient distribution in the area's food chain.

"We want to know what happens ecologically to a polluted ocean coast region. The question is, how will the ecosystem change in this bay?" Chen said.

Already Chen has shown that river output can cause the frontal zone -the boundary zone between fresh water and salt water- along the coast to fluctuate. Nutrients can accumulate within the frontal zone, and hence lead to a phytoplankton bloom. Also, wind can transport polluted water from coastal areas to offshore regions. This affects not only local waters near the shore but offshore waters as well.

"This is an example of how we can relate a local study to a larger global study. It can also show what can potentially happen here [in Georgia] if we don't use our environmental resources wisely," Chen said.

In addition to the East China Sea and the Georgia coast, Chen has collaborated with other researchers to study the Georges Bank near Maine, funded by the National Science Foundation (NSF) and NOAA through the U.S. Global Ocean Ecosystems Dynamics program. He also studies Lake Superior and Lake Michigan with NSF funds, and the Louisiana-Texas continental shelf with funds from the Office of Naval Research.

Through his research, he has discovered a concentration of nutrients close to the ocean's floor in the frontal zone. He and collaborating biologist Peter Franks of the Scripps Oceanographic Institute found scallops living as deep as 88 yards beneath the surface and surviving on nutrients pumped down to them by tidal currents.

Chen also studies the current global incidence of "red tide," a term used for the concentrated presence of certain phytoplankton in offshore regions that gives the water a reddish hue. The phytoplankton that cause red tides are deadly to zooplankton and potentially harmful to seafood crops such as oysters and scallops, Chen said.

"We are looking at how we can use a model to predict the occurrence of this phytoplankton bloom -when it can happen and under what conditions," he said.

Also of interest to Chen will be the phytoplankton bloom's effect on the ecosystem in these areas.

"I believe that the marine ecosystem will become the most important issue in the next century," Chen said. "We should look at the ocean system as one system, not as a physical or biological system, because they both interact."

For more information, e-mail Changsheng Chen at chen@whale.marsci.uga.edu or view his models online at http://www.marsci.uga.edu.

Dawn T. Pick is a Research Reporter intern and a graduate student at UGA's Grady College of Journalism and Mass Communication. She has bachelor's degrees in history and international studies.

by DTP

Since the beginning of time, the world's oceans have been essential to Year of the Oceannature's processes and civilizations' survival. Oceans are vital to the life-sustaining cycling of water, minerals and nutrients. They also fuel global weather patterns and provide a storehouse of seafood crops and life-saving medicines.

Because of short-sighted human activities, many fragile marine environments are now threatened, their rich diversity of ocean life imperiled.
Scientists have identified five leading factors that contribute to the loss of marine biodiversity:

-overexploitation of ocean organisms;
-physical alteration of ecosystems;
-disruption of local food webs by organisms from distant waters; and
-global atmospheric changes.

The United Nations has declared 1998 the Year of the Ocean (YOTO) to raise awareness of the ocean's fragileness, to foster wise stewardship of marine environments and to inspire people to change their views about oceans.

For information about YOTO events and educational initiatives, visit theirwebsite at http://www.yoto98.noaa.gov/.


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