Regulation of keystone predation by small changes in ocean temperature

Key species interactions that are sensitive to temperature may act as Lever age points through which small changes in climate could generate Large chan ges in natural communities. Field and laboratory experiments showed that a slight decrease in water temperature dramatically reduced the effects of a keystone predator. the sea star Pisaster ochraceus, on its principal prey. Ongoing changes in patterns of cold water upwelling, associated with El Nin o events and Longer term geophysical changes. may thus have far-reaching im pacts on the composition and diversity of these rocky intertidal communitie s.