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Limited effects of a keystone species: Trends of sea otters and kelp forests at the Semichi Islands, Alaska

Marine Ecology Progress Series
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Abstract

Sea otters are well known as a keystone species because of their ability to transform sea urchin-dominated communities into kelp-dominated communities by preying on sea urchins and thus reducing the intensity of herbivory. After being locally extinct for more than a century, sea otters re-colonized the Semichi Islands in the Aleutian Archipelago, Alaska in the early 1990s. Here, otter populations increased to about 400 individuals by 1994, but rapidly declined to about 100 by 1997. Roughly 7 yr after initial otter re-colonization, there were only marginal changes in sea urchin biomass, mean maximum test size, and kelp density. These small changes may be the first steps in the cascading effects on community structure typically found with the invasion of a keystone species. However, no wholesale change in community structure occurred following re-colonization and growth of the sea otter population. Instead, this study describes a transition state and identifies factors such as keystone species density and residence time that can be important in dictating the degree to which otter effects are manifested.

Suggested Citation

Konar, B., 2000, Limited effects of a keystone species: Trends of sea otters and kelp forests at the Semichi Islands, Alaska: Marine Ecology Progress Series, v. 199, p. 271-280.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Limited effects of a keystone species: Trends of sea otters and kelp forests at the Semichi Islands, Alaska
Series title Marine Ecology Progress Series
Volume 199
Year Published 2000
Language English
Publisher Inter-Research Science Center
Description 10 p.
First page 271
Last page 280
Country United States
State Alaska
Other Geospatial Alaid Island, Nizki Island, Semichi Islands, Shemya Island
Additional publication details