Sea otters are keystone predators that maintain the dense, productive forests of kelp in coastal Alaska. Kelp forests are habitat for many invertebrates that are food for over 20 species of fish; these forests also provide spawning habitat for herring and Atka mackerel as well as nursery areas for salmon fry. Many birds, such as sea ducks, use them for resting and feeding. The forests of giant algal fronds protect the coastline from severe wave action and, like our land-based forests, absorb carbon dioxide from the atmosphere, helping to reduce global warming.
Kelp forests provide a variety of recreational opportunities: Tourists appreciate the chance to observe high-diversity marine habitats from glassbottomed boats and to watch the sea otters; where kelp fronds smooth the water surface, kayakers can take refuge from rough water; SCUBA divers explore the rich habitats.
The major threat to these rich kelp forests is grazing by sea urchins, which can decimate the forest and prevent regrowth of the fronds. Sea otters are the main predator of sea urchins and keep the urchin population in check. Sea urchins greedily graze on kelp when otters are not around, but in the presence of the predators, urchins hide in crevices and eat just the plant scraps. Loss of sea otters therefore can have a huge impact on our coastal ecosystems.