SEA GRANT STORY IDEA TIP SHEET FOR FEB. 6, 1998
SO FAR, RUFFE NOT AS GREAT A THREAT AS ORIGINALLY THOUGHT Since its discovery in 1986 in Lake Superior's St. Louis River, the Eurasian ruffe has been thought to be a considerable threat to the delicate predator-prey balance necessary to maintain flourishing commercial and sport fisheries in the nation's waters.
More than ten years later, biologists contend that healthy sport and forage fish populations are being sustained in ruffe-infested areas. Ohio Sea Grant Extension Specialist Fred Snyder agrees with Lake Superior biologists who believe that if ruffe were going to wipe out fisheries they would be doing it by now. Researchers are finding that ruffe diets and yellow perch diets do not have much overlap -- a major fear over the last ten years. So far, ruffe have only been sighted in Lake Superior waters.
According to Snyder, when ruffe eventually reach Lake Erie, there will be some initial disruptions, but, like aquatic communities in Lake Superior, the ecosystem will survive with fisheries intact. Lake Erie's tremendous ecosystem diversity and abundance, Snyder contends, should provide good resilience when the ruffe arrive. "Although we need to resist further invasions of exotics and do our best to minimize spreads and impacts," Snyder adds, "the available information indicates that Lake Erie is likely to absorb the ruffe invasion eventually without major consequences."
CONTACT: Fred Snyder, Ohio Sea Grant Extension Specialist, (Port Clinton, OH), (O) 419-635-4117; E-Mail: [email protected]
ESTUARIES, OCEAN CURRENTS CRUCIAL TO SUCCESSFUL SHRIMP FISHERY Georgia Sea Grant researchers Jack Blanton and Peter Verity and their colleagues are trying to determine what oceanographic conditions favor the transport of white shrimp larvae from the ocean to their estuarine nursery grounds. Estuarine environments, like salt marshes, are crucial habitat for many commercially important species of fish and shellfish.
Blanton and Verity have been studying white shrimp, one of Georgia's most valuable fishery resources, in the tidal inlets and estuaries of Georgia and South Carolina. The number of shrimp larvae that reach the salt marsh nursery grounds determine to a large extent the quantity that mature into adult shrimp. The researchers are finding that only certain wind conditions generate the optimum ocean currents needed to efficiently transport larvae from the ocean into the inlet.
Their computer simulations indicate that larvae enter the inlets from long and narrow zones which are less than two miles wide, but that can extend for nearly 20 miles along the coast. This finding, the researchers say, suggests that jetties and other man-made structures may block larvae from entering the inlet and potentially lower successful recruitment of shrimp into the adult fishery.
Blanton and Verity are hopeful that a better understanding of the oceanographic conditions that favor efficient transport of larvae into estuaries will give resource managers a tool that will enable them to predict the potential for successful commercial and recreational harvests.
CONTACT: Peter Verity, Sea Grant Researcher, (Savannah, GA), (O) 912-598-2471; E-Mail: [email protected]
RESEARCHERS WORK ON METHODS TO MASS PRODUCE CANCER-FIGHTING COMPOUNDS Rhode Island Sea Grant researcher Yuzuru Shimizu and his colleagues are developing large-scale aquaculture systems to grow marine organisms called dinoflagellates and other microalgae that have shown significant anti-tumor capabilities.
Although scientists have identified marine organisms such as dinoflagellates, sponges and corals as having great pharmaceutical potential, the largest barrier to their commercial development has been getting enough material to work with while maintaining an adequate future supply. Promising compounds often exist only in trace amounts and massive collections are a matter of ecological concern.
Shimizu and his team are using 15,000-liter tanks to test the feasibility of large-scale culturing. The tanks are roughly the same size as industrial production units. It is hoped that this large-scale research will dispel the industry's concerns about the ability to supply the quantity of the compound needed for successful development.
"It is not an overstatement that without the establishment of mass culture systems, all past and ongoing efforts in marine natural products chemistry will be wasted," Shimizu said. "Successful mass culture will enable us to conduct preclinical and clinical tests of promising potential drugs, and will eliminate the industry's concern about the supply of the compounds in the event they become therapeutic drugs."
Shimizu and his team are also developing a more efficient continuous culture system using a fermentor with fiber optics and other state-of-the-art control and monitoring systems.
CONTACT: Yuzuru Shimizu, Rhode Island Sea Grant Researcher, (Kingston, RI), (O) 401-874-2752; E-Mail: [email protected]
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