Kelp Communities and Sea Otters: Keystone Species or Just Another Brick in the Wall?

Abstract

Recent reviews have discussed the effects of many biotic and abiotic factors on the abundances of kelp species and how these vary in space and time (Dayton 1985a; Foster and Schiel 1985; Schiel and Foster 1986). Giant kelp (Macrocystis pyrifera) communities along the California coast have been of particular interest because of the diversity of organisms they harbor, their importance to nearshore productivity, and their economic and recreational value (reviewed in Foster and Schiel 1985). The need to develop management directives for these nearshore communities has fostered much debate about the relative importance of various factors affecting community structure, and has engendered what we see as essentially opposing views about the development and maintenance of community structure. The focus for this debate has been the sea otter, Enhydra lutris, which presently occurs along the coasts of central California, Alaska, Washington, and British Columbia (Riedman and Estes, this Vol.). Sea otters consume a variety of invertebrates, particularly sea urchins and abalone, which can be important consumers of kelp.