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THE SCIENCE BEHIND EL NINOAmong the diverse scientific disciplines supported through NSF grants,
research on El Niño is yielding particularly fascinating and current
insights during this year's El Niño event, the strongest in recorded
history. Below are some examples of NSF-funded research on this worldwide
climate phenomenon. All are funded by NSF's biological oceanography program. Contents of this News Tip:
CORAL REEF BLEACHING: IS EL NINO TO BLAME?Coral bleaching has become a subject of increasing attention, with mass mortality of corals receiving widespread coverage in the press. Although several theories about coral bleaching have been advanced, new research by NSF-funded scientist Howard Lasker of the State University of New York at Buffalo shows that past El Niño events correlate with Caribbean-wide coral bleaching. He believes that massive coral bleaching can once again be expected along the Caribbean coast early this summer. "The present El Niño event is the strongest in recorded history," explains Lasker, "surpassing both the 1982/83 and 1986/87 events, both of which were associated with Caribbean coral bleaching. If the current El Niño follows this pattern, more coral bleaching, possibly much more, will likely result." In research now underway, Lasker is looking at the effects of the predicted bleaching on one species of coral found along the Panama coast. He hopes that extensive baseline data will allow for comparisons of reproductive status of this coral as far back as a decade ago. The biologist also hopes to learn how El Niño affects populations of zooxanthellae, algae that live symbiotically within certain corals and give these corals their bright hues. WHEN EL NINO COMES, FISH GONo part of the marine environment in an area affected by El Niño escapes the phenomenon's ravages. During an El Niño, trade winds weaken and change direction, decreasing the amount of upwelling, or return of nutrients, that reaches the ocean's surface waters. When nutrients no longer are found in the sunlit upper waters of the sea, production of tiny plants called phytoplankton slows down. Fewer phytoplankton means less food available for the ocean animals that depend upon these microscopic plants. Eventually, higher trophic levels are affected, with the result that fish usually found in a given area go elsewhere in search of food. Scientist Peter Klimley of the University of California at Davis has received an NSF grant to study how El Niño affects the distribution and migratory behavior of several species of fish. "In the past, these kinds of studies have been confined to salmon off the coast of Oregon, sea turtles in the eastern tropical Pacific, and pinnipeds in the eastern temperate Pacific," explains Klimley. "My research will go beyond those studies to include the response of an assemblage of fish to El Niño." Klimley and his associates are conducting visual censuses of adult fish, tagging fish with coded acoustic beacons, and detecting their presence with electronic listening devices. The instruments are moored on seamounts and islands in the Gulf of California and off the Pacific coast of the Baja Peninsula. Adds Klimley, "Through this work, we'll be able to extend northward the efforts of our Mexican colleagues to the south, and look at how El Niño has affected marlins, sharks, tunas, and other fish across hundreds of miles of ocean." EL NINO SPELLS DISASTER TO GIANT KELP COMMUNITIESUnusually large Pacific Ocean waves have damaged more than posh retirement homes along California's coast, say scientists like Jim Estes of the University of California at Santa Cruz. Estes was awarded a grant from NSF to study populations of giant kelp (Macrocystis pyrifera) throughout the seaweed's range--central Baja, Mexico to Ano Nuevo, California. The biologist believes that this year's El Niño has significantly impacted giant kelp. He cites major changes in the structure of the extensive giant kelp plant and animal community as a result of large ocean waves and increased water temperatures. Giant kelp provides one of the most important habitats along the Pacific coast. "To estimate 'pre-El Niño' conditions," explains Estes, "90 sites representing 18 geographic locations were surveyed using scuba gear in the late summer of 1997. To estimate 'mid-' and 'post-El Niño' conditions, all sites have been resurveyed during periods of severe storm activity in February, March and April, and will be again in June and July after the period of severe storm activity." Estes and his colleagues will also monitor giant kelp for the next three years, looking at the long-term effects of this year's El Niño.
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