Sea otters are a keystone species. They play a major role in the community by controling of herbivorous invertebrates, mainly the sea urchin (Strongylocentrotus sp.), inhabiting kelp forests. Sea urchins graze on kelp. In coastal areas where otters are absent, sea urchins are abundant and the area is devoid of kelp forests. Where sea otters are present, the urchins are limited by otter predation and kelp forests are abundant. Kelp forests are dependent on sea otters for protection from grazers. The diversity of the sea otter diet reduces competition between benthic grazers and supports greater diversity in those species. The presence of sea otters is believed to be important in the evolution of kelp forest ecosystems.
(Estes and Palmisano 1974; Estes et.al. 1978; Estes 1980; Cohn 1998; Estes and Duggins 1995)
Ecosystem Impact: keystone species