November 23, 1998

Wildlife biologist to deliver lecture on carnivores and their role in nature

By Tim Stephens

The public is invited to a free lecture on the role of carnivores in natural ecosystems, presented by James Estes, adjunct professor of biology and ocean sciences and a U.S. Geological Survey biologist. The lecture, sponsored by the UCSC chapter of the scientific research society Sigma Xi, will be held Thursday, Dec. 3, at 7:30 p.m. in Room 105, Oakes College.

Nature's balance is off kilter in Alaska's Aleutian archipelago, where sea otters have become food for killer whales.

Estes has been studying the role of sea otters in the coastal ecosystem of Alaska's Aleutian archipelago since the early 1970s. His research has documented how sea otters maintain the coastal kelp forests by controlling populations of sea urchins and other animals that graze on kelp. The kelp forests in turn provide food and habitat for a broad range of species.

Recent observations by Estes and his coworkers, published in the Oct. 16 issue of the journal Science, revealed a startling decline in sea otter populations, followed by increases in sea urchins and the collapse of the kelp forests. The researchers traced the decline in sea otters to predation by killer whales, which shifted their diet to sea otters after the populations of their usual prey, seals and sea lions, decreased dramatically.

These new findings, which have received widespread attention from both scientists and the popular press, demonstrate the importance of long-term ecological field studies, Estes said.

In his lecture, entitled "Carnivores and the Balance of Nature," Estes will draw on these and other findings to discuss the role of carnivores in regulating the organization of ecological communities in general.

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