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The USGS lunar calibration program provides radiometric calibration and sensor stability monitoring for space-based remote sensing instruments using the Moon as a reference source. This is a unique on-orbit calibration technique for solar reflectance wavelengt... more.
Laura Lee News - Scientists Examine The Seas Our Ancestors Fished To Better Understand Today's Changing Oceans
"Successful management and restoration of coastal marine ecosystems has failed in part because of a lack of understanding the deeper historical causes of collapses in these ecosystems," said Dr. Jim Estes, a USGS research ecologist with the Western Ecological Research Center in Santa Cruz, Calif., one of the authors of the article.
"Since most ecological studies of coastal marine ecosystems have been conducted after the 1950's, scientists have had first-hand knowledge of only the recent structure and function of these ecosystems," said Estes. In the North Pacific, where Estes has studied nearshore ecosystems since the 1970's, historical evidence showed that aboriginal Aleuts greatly reduced the number of sea otters starting about 2,500 years ago. By preying on sea urchins, sea otters prevented urchins from overgrazing the kelp forest. Hence, with fewer sea otters to control them, the sea urchins grew larger, reducing the kelp. When fur traders hunted the remaining sea otters to the brink of extinction in the 1800's, the kelp forests disappeared from overgrazing by sea urchins and didn't appear again until legal protection partially restored sea otters. Estes found that recent depletions of the kelp forest have occurred in areas of Alaska where killer whales are preying on sea otters. The whales recently shifted their diet to sea otters from seals and sea lions. Estes said the seals and sea lions apparently have declined because of food web changes associated with whaling and fishing, and because ocean warming is decreasing the productivity of the North Pacific. Historical perspective also made possible the comparison of kelp forests of Alaska to those of the southern hemisphere, in research in the 1990's. While sea otters had been hunted to near extinction in California by the 1800's, Estes said the kelp forest response to the absence of sea otters was different than it had been in Alaska. Estes said exploring the evolutionary role of sea otter predation of sea urchins in California revealed that southern kelp had developed strong defenses against plant eaters that made them less susceptible to sea urchin overgrazing than Alaska kelp forests, which lacked such defenses.
Institute for Ocean Conservation Science
PI: James Estes, University of California, Santa Cruz; John Terborgh, Duke University*
Dr. James Estes, Research Scientist with the U.S. Geological Survey and Adjunct Professor at the University of California, Santa Cruz, and Dr. John Terborgh, Director of the Duke University Center for Tropical Conservation, convened a group of 21 world-class scientists who have studied the ecological roles of large predators. James Estes, PhD Dr. James Estes is an international expert on sea otters and a specialist in the critical role of apex (top level) predators in the marine environment. He has been a research biologist at the Western Ecological Research Center of the U.S. Geological Survey for more than 20 years. Estes also holds academic posts as research associate and adjunct professor with the Center for Marine Studies at the University of California, Santa Cruz. His interest in predation as an ecosystem-level process began in the early 1970s, after he began working with sea otters. Using the otters' fragmented distribution across the Aleutian archipelago (which resulted from a history of near-extinction and recovery), he and a colleague discovered the species' keystone role in kelp forests by comparing islands where it was abundant or rare. This work provided a spectacular example of how apex predators influence ecosystem functions. Estes continued to explore the dimensions of sea otter-kelp forest interactions over the next 30 years, including the unanticipated collapse of sea otters and kelp forests in western Alaska. He has now published nearly 70 scientific articles and reports on wildlife ecology, predation and conservation, and was lead editor of the 2007 book, "Whales, Whaling, and Ocean Ecosystems. Estes is a recipient of the prestigious Pew Fellowship in Marine Conservation (1999). Dr. Estes' Pew Fellows in Marine Conservation webpage
Jim Estes, Research Scientist, U.S. Geological Survey
Edited by John Terborgh and James A Estes
Edited by John Terborgh and James A Estes James A Estes After spending most of his career as a research scientist with the US Geological Survey, James A. Estes is currently Professor of Ecology and Evolutionary Biology at the University of California, Santa Cruz.
Books by James A Estes
After spending most of his career as a research scientist with the US Geological Survey, James A. Estes is currently Professor of Ecology and Evolutionary Biology at the University of California, Santa Cruz .