shelter creatures support food chain sea urchins feed kelp sea otters feed sea urchins rapid decline sea otters due overhunting sea urchin populations grazed unrestricted kelp beds ecosystem collapsed left unchecked urchins destroyed shallow water kelp communities supported steller 's sea cow 's diet hastened demise sea otter thought keystone species coexistence many ecological associates kelp beds relied upon otters survival however later questioned turvey risley ref name pmid ref
Applied science Public administration Conservation biology