SEA GRANT NEWS & NOTES FROM AROUND THE NATION - MARCH 6, 1998
HYBRIDIZATION STUDIES MAY HELP CONSERVE SALMON BIODIVERSITY
Growing evidence suggests that hybridizing two diverse salmon stocks, such as native and transplant, may reduce genetic fitness and productivity, a condition called outbreeding depression. Alaska Sea Grant graduate student researcher Ivan Wang is studying pink salmon to see if outbreeding depression occurs when genetically isolated salmon populations are interbred. He is looking at the embryonic stages of the salmon to determine how fast they develop. If an embryo develops too fast or too slowly, it has a decreased chance of surviving in the ocean.
Wang, who is earning his degree under Alaska Sea Grant researcher A.J. Gharrett, is also comparing the development rates of gills and pectoral fins on the left and right sides of hybrid and genetically isolated salmon. A higher than normal rate of asymmetry might indicate genetic disturbance.
Wang is hopeful that the results of his research will help in conserving wild salmon populations in Alaska and be useful in rebuilding populations in the Lower 48 states.
CONTACT: Ivan Wang, Alaska Sea Grant Graduate Student Researcher, (Juneau, AK), (O) 907-465-6441; E-Mail: [email protected]
SEA GRANT RESEARCHERS IDENTIFY NEW METHODS TO ELIMINATE ZEBRA MUSSEL
Since the discovery of zebra mussels in North American waters 10 years ago, scientists have been investigating ways to control the pesky mollusk that has become famous for clogging boat intakes and electric and water facility intake pipes. One critical point in zebra mussel control is the prevention of settlement of their larvae, called veligers.
Two New York Sea Grant research teams have identified technologies that eliminate the zebra mussel veliger. One method, developed by Linda Chalker-Scott and her team, involves zapping larvae with high-intensity ultraviolet radiation. Chalker-Scott and her colleagues found that, in the lab, brief ultraviolet exposure (one to two seconds) paralyzes the veligers for nearly 20 minutes. This is enough time for the larvae to be swept through most water intake systems, prohibiting settlement and colonization on intake pipes. The researchers also found that a longer exposure of five seconds killed the veligers instantly. According to Chalker-Scott, the UV prototype is currently being used by a private company seeking to market a control device.
Another project, led by New York Sea Grant researcher John Van Benschoten, examined what effects coagulants have on controlling zebra mussels. Coagulants are chemicals that cause particles in the water to stick together and form a mass. Van Benschoten and his colleagues recognized early
in the study that the coagulants could have potential adverse effects due to the formation and settlement of floc (the mass formed by coagulants) in the intake pipes. They found that coagulants killed veligers largely because they make water more acidic. As a result, the scientists concluded that mild acidification of water at the intake shows great potential for water utilities needing to control mussels.
CONTACT: Linda Chalker-Scott, New York Sea Grant Researcher, currently at the University of Washington, (Seattle, WA), (O) 206-685-2595; E-Mail: [email protected] or John Van Benschoten, New York Sea Grant Researcher, (Buffalo, NY), (O) 716-645-2114, ext. 2330; E-Mail: [email protected]
SILVER MAY BE AN ANSWER TO TRACKING DOWN NUTRIENT SOURCES
North Carolina Sea Grant researcher Stephen Skrabal believes dissolved silver may be a tool to distinguish nutrient inputs that drain into coastal-bound rivers from point sources such as sewage treatment plants and industrial outfalls and from nonpoint sources such as city streets, farms and forests.
If too many nutrients float downstream, coastal rivers can become overly enriched or eutrophic. The result may be algal blooms, dead water zones and fish kills. While limitations on nutrient inputs are needed, scientists must first determine the sources and amounts of nutrients flowing into rivers.
Using water samples from the Cape Fear River, Skrabal will conduct analyses to test the hypothesis that pollutant inputs resulting from industrial or sewage sources have low silver ratios, whereas inputs from agricultural runoff have relatively higher ratios. If the hypothesis proves correct, dissolved silver may be used as a tracer for nutrient sources.
CONTACT: Stephen Skrabal, North Carolina Sea Grant Researcher, (Wilmington, NC), (O) 910-962-7160; E-Mail: [email protected]
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