SEA GRANT STORY TIP SHEET, MAY 5, 1999
GREAT LAKES' ALGAE CIRCULATION A KEY TO TRACKING POLLUTANTS
Russell Cuhel, in a project funded by University of Wisconsin Sea Grant Institute, has identified how long it takes for particles, possibly including pollutants, to settle on the bottom of Lake Michigan.
Pollutants like PCBs and DDT often enter the Great Lakes attached to particles flowing down rivers or falling out of the atmosphere. Understanding what happens to these contaminants after they enter the lakes requires, in part, determining how long small particles remain suspended in the water before they settle out on the bottom. Wind blowing across the Great Lakes makes water circulate in patterns that make this a difficult question to answer.
"Physical oceanographers have torn their hair out for decades trying to get at the actual rate at which water moves vertically in a windy situation," said Cuhel.
Using algae, Cuhel devised a partial solution. During the winter and spring, Lake Michigan circulates from top to bottom, and algae ride along, changing their biochemistry as they go from light to dark zones. Cuhel showed that when water circulates from top to bottom in the lake, algae obtain phosphorus only when they are near the bottom. He also realized that the algae must circulate often enough to obtain phosphorus at the same rate that they use it up. Cuhel measured this rate in his laboratory and found that algae showed signs of phosphorous deficiency in two to five days. From this Cuhel concluded that algae must circulate in Lake Michigan during winter and spring at least every two to five days. Therefore, in winter or spring, circulating water carries contaminated particles to the lake bottom in just a few days, about two to four times faster than they would fall in still water.
CONTACT: Russell Cuhel, Sea Grant Researcher, (Milwaukee, WI), (O) (414) 382-1711; [email protected]
SEA GRANT HELPING TO RESTORE OYSTER THROUGH HATCHERY EFFORT
Spring brings reason for hope in the Chesapeake Bay - the oyster, a commercially and environmentally important shellfish, is making a tentative comeback. Decimated by habitat loss, pollution, and two parasitic diseases (MSX and Dermo), oyster populations in the Bay have plummeted over the past 50 years. The recent good news comes from commercial harvest totals that topped 300,000 bushels in 1998-1999, a three-fold increase over harvests of just five years ago. While that figure falls far below the 1 million-plus bushel harvests recorded in the mid-1980s, the National Sea Grant College's Oyster Disease Research Program (ODRP), set-up by Congress in 1989, is hoping to continue this positive trend. Establishing disease-free oyster beds in the Chesapeake is one focal point of this multi-state, multi-million dollar research effort.
Sea Grant scientist Don Meritt, a biologist at the University of Maryland Center for Environmental Science, has been testing the development of disease-resistant hatchery oyster seed. In 1998, Meritt and his colleagues produced more than 20 million oyster spat at the Horn Point Laboratory - a major achievement for a research facility. Working with the Oyster Recovery Partnership, they then "seeded" oyster beds in the upper Choptank River. To date it appears that the experiment is working. The true test will come next fall, when those spat approach market age and size. The number of survivors, and overall health of the community will help determine if hatchery efforts can help restore this important contributor to the Bay's overall water quality.
Meritt is optimistic, saying, "The best way to produce oysters that are without disease is in hatcheries from stocks that are themselves free of disease."
CONTACT: Don Meritt, (Horn Point, MD), (O) (410) 228-8475; [email protected]
HAWAII SEA GRANT'S COASTAL TOURISM EFFORT WINS VICE PRESIDENT GORE'S "SILVER HAMMER" AWARD
Hawaii Sea Grant's Recreation and Tourism Extension Agent Christine Woolaway and Communications Director Priscilla Billig have won Vice-President Al Gore's National Performance Review Silver Hammer Award for their contributions to the Northwestern Hawaiian Islands Marine Reef Cleanup Team.
U.S. Senator Daniel Inouye presented the award last month in recognition of significant efforts at reinventing government by partnering with private industry, city and county, state and federal agencies, civic organizations and academia, while maximizing resources and reducing cost.
Spearheaded by Woolaway, the unprecedented partnership pooled substantial resources to clean up damaging derelict fishing nets from coral reefs around the Northwestern Hawaiian Islands. Billig provided communications support which helped focus public attention on the impacts of marine debris on Hawaii's coral reefs and wildlife. The effort saved an estimated $920,000 in operational costs for removing six tons of marine debris from this fisheries resource which also serves as a critical habitat for the endangered Hawaiian monk seal. Having gained public support, the partnership is now central to the continuing efforts to protect Hawaii's fragile coral reef ecosystem.
CONTACT: Priscilla Billig, Communications Director, Hawaii Sea Grant College Program, (Honolulu, HI), (O)(808) 956-2414, [email protected]
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