Otters are known for their playful, fun-loving spirits. But it turns out that the carefree southern sea otters of central California’s coast have had a secret mission: working to fight the devastating loss of kelp forests due to anthropogenic climate change.
In the nineteenth century, southern sea otters were nearly hunted to extinction by trappers who sold their pelts. Precisely where the southern sea otter numbers plummeted along the California coast, kelp forests suffered because of a variety of environmental pressures.
Using historical surveys to perform an extensive study of the area of kelp forests from the early 1900s until today, researchers discovered that in Northern and Southern California, kelp decreased by 63 and 52 percent, respectively. However, California’s central coast was different. Here, the sea otters survived initially in small numbers, and gradually grew over time with conservation protections. The study suggests, that because of the sea otters the kelp forests along the Central California grew by around 56 percent! What makes this even more impressive is that the growth of kelp in Central California happened during a period of significant ocean warming.
The study cements an understanding of sea otters as a keystone species, that is a species whose presence in an ecosystem has long lasting downstream impacts on that ecosystem. While scientists are still studying the precise mechanisms that enables otters to help kelp thrive, one known factor is their voracious appetite. Otters eat kelp-eating sea urchins, which, if are otherwise left unchecked, can crush an already stressed ecosystem. The study suggests that one solution may be reintroducing sea otters to their historical habitats in Southern and Northern California.
