Sea Otters Important to Environment Balance

Photo courtesy of UCSC	Many fish species, like herring,  rely on the kelp as a surface for their  larvae to use as settlement habitat.  Meanwhile adult fish feed and hide  in the kelp fronds. Invertebrates such  as crabs, snails, bryozoans, ascidians,  sea urchins, clams, and shrimp are  also found in kelp forests. Some use  the blades as living habitat, while  others feed on the kelp itself. Sea otters also find safety and food in  kelp forests. They feed on the  sea urchins, clams, and crabs that  live in this undersea forest. The long  stands of kelp provide good protection  from predators. Humans have also begun to commercially  harvest kelp. Kelp can be processed into  nutritional supplements for direct human consumption, or into fertilizer ( www.biology.ucsc.edu/people/raimondi/readdie/ecology.htm)
Tall stands of giant kelp attach to rocky substrate to form dense forests that create a three-dimensional habitat. The ocean is truly a 3-D world where there are no hiding places. An animal swimming in the water column can be attacked from every direction. Kelp forests offer a haven for protection as well as hard surface for settlement.
Sea otters and sea urchins in the kelp forest.  This picture shows an urchin barren.  Purple and red sea urchins cover most of the outcropping.  Only a few stipes and stands of kelp remain.
Sea urchins are voracious herbivores. They climb up the holdfast and graze on the stipe, as well as eat drift algae that accumulate on the ocean bottom. Studies have found urchins responsible for completely removing kelp from an area, leaving it an urchin barren. Sea otters feed primarily on sea urchins, and thus are an important predator in the kelp forest. Aleutian Islands that have been recolonized by sea otters now have thriving kelp forests where extensive urchin barrens once dominated. (www.biology.ucsc.edu/people/raimondi/readdie/ecology.htm; Estes and Palmisano, 1974)