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For more information on these science news and feature story tips, please contact the public information officer at the end of each item at (703) 292-8070. Editor: Cheryl Dybas Contents of this News Tip:
DECADES-LONG CLIMATE CYCLE--EL NINO'S "COUSIN"--INFLUENCES SALMON FISHERIESResearchers funded in part by the National Science Foundation (NSF) and affiliated with the University of Washington in Seattle believe that a decades-long climate variation in the Pacific Ocean may explain changes in salmon harvests off the U.S. West Coast and Alaska over the course of this century. The scientists call this climate phenomenon the Pacific decadal oscillation, or PDO. John Wallace, Steven Hare, Nathan Mantua and others found the connection by comparing climate records for the Pacific Basin over the past century with records of salmon catches from Alaska and the Pacific Coast states. When records back to the year 1900 were studied, two El Niño-like climate fluctuations with warm and cold phases lasting from 10 to 30 years came to light. These phenomena, the researchers think, are distinctive features of the PDO. The PDO leads to widespread changes in biological productivity throughout the North Pacific Ocean, explains Mantua. "Since 1977, the PDO has been in the phase in which Alaskan salmon production has been booming. In this same period, West Coast salmon numbers have been 'alarmingly low,' a fact that has been attributed to both human influences and poor ocean climate conditions." [Cheryl Dybas] SLEEPY ADOLESCENTS? STUDENTS LEARN ABOUT BIOLOGICAL CLOCKSA unique program at the University of Virginia-based Center for Biological Timing (CBT), an NSF-funded Science and Technology Center, is providing students with remote access to real-time experiments on biological clocks with the launching of an innovative web site designed especially for students in middle school science classes. Using the theme "The Mystery of Sleepy Adolescents," the project has elements that attract young students: the Internet, and relevance of science to the students' lives. The web site (http://www.cbt.virginia.edu/Olh) explores the daily rhythms of animal behaviors, the human sleep/wake cycle and the struggle of young adolescents to get up in the morning. Using the Internet, students can view and download results of experiments as they are being conducted. Low-light digital camera equipment is being fine-tuned so that students will be able to view the behavior of nocturnal animals in real-time. In addition, students will have the opportunity to analyze the data, compare their thoughts with the ideas of young scientists in other schools around the world, and receive on-going curriculum support from CBT scientists. For teachers there are extensive background materials. CBT scientists say that this innovative model project is garnering the praise of teachers, students and research colleagues around the country. [Lee Herring] MODERN MAMMALS LIVED BEFORE EXTINCTION OF DINOSAURSOverwhelming evidence from the largest evolutionary study of gene sequences ever performed shows that the major groups of mammals emerged well before the extinction of the dinosaurs, according to NSF-funded researchers at Penn State University. "The evolution of mammals appears to have occurred gradually by the isolation of breeding groups when the continents broke apart, not suddenly by the rapid filling of ecological niches left vacant when the dinosaurs became extinct," says S. Blair Hedges, one of the lead scientists on the project. The massive gene study suggests that modern orders of mammals first evolved when the continents were separating during the Cretaceous era about 100 million years ago. This is much earlier than some previous estimates based on fossil studies, which link the evolutionary event to mass extinctions 65 million years ago. "This is the first time we have been able to estimate when all these lifeforms appeared on earth," says Hedges. "Fossils can't give us this information, partly because there are huge periods of earth's history from which not enough fossils have been found to make reliable estimates." Mammals definitely were living on earth during the Cretaceous period from 70 to 100 million years ago, according to Hedges. "We don't yet know what they looked like, but from the genes of their descendants we now know that they were there." [Cheryl Dybas]
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