GEF

Unit 4   |  The Global Ecosystem 98 the otters’ main food, sea urchins, increased. The boom in sea urchins took a heavy toll on marine kelp forests, which are fed upon by urchins. In turn, the decline in kelp forests allowed coastal erosion to increase. As a result of studying this chain of relationships, sea otters were recognized as a keystone species , a vital regulating component, of these coastal ecosystems. Protecting the otters and their reintroduction into waters off British Columbia, Alaska, and California has dramatically improved the health of these ecosystems. Sea otters are a keystone species for many coastal ecosystems. It is important to understand ecosystem services —the ben- efits natural processes provide to our wellbeing. The more we understand our dependency on nature, the better decisions we can make toward sustainability. KEYSTONE SPECIES A species that has a vital regulatory influence on its ecosystem. ECOSYSTEM SERVICES Valuable services, such as crop pollination and flood control, which are provided by natural ecosystems.