When I saw my first sea otter, I thought to myself, “Wow! It’s so cute and furry.” Little did I know that such an adorable, curious creature could have such a significant impact to the marine environment.
Sea otters are often referred to as a keystone species in the scientific world. A keystone is the top centre stone of an archway — the stone that holds the archway together — and without it, the archway collapses. Like the keystone in the archway, the sea otter is the keystone species that holds the kelp forest ecosystem together.
An ecosystem is a community of different animals living together and interacting in a particular place. Many of the interactions among the animals are about eating, something most of us can relate to. In the case of sea otters, they enjoy eating round, prickly animals called sea urchins. Sea otters dive down to the sea floor, pick up the sea urchins and bring them to the surface, where they crack them open and eat the inside. Sea otters need to consume up to 30 per cent of their body weight every day to survive and, therefore, eat a large number of sea urchins and other seafood daily.
When sea otters were hunted to near extinction in the mid-1800s, the sea urchin populations boomed due to less predation from sea otters. Sea urchins eat seaweed and in the Pacific Northwest we have kelp, a type of seaweed. Kelp grows in forests along our coastlines and is one of the fastest growing seaweeds in the world — they can grow up to a 30 centimetres per day in the summer. Unlike trees that grow significant roots to anchor themselves to the ground, kelp has a small holdfast that anchors it to the sea floor. Sea urchins also live on the sea floor so when they eat the holdfast, the rest of the kelp just floats away. The result is what scientists call an “urchin barren.”
When sea otter populations are sufficient, they keep the sea urchins in check and the kelp forests thrive. When the sea otter populations are not sufficient, the sea urchin population increases and the kelp forests, along with the animals that live in them, disappear.
You can learn more about sea otters and the important role they play on our coasts at the Vancouver Aquarium’s next public event, Sea Otters: A Natural History, with Dr. Jane Watson. Register to attend the event in person, or join us online during the webcast.
Dr. Jane Watson is a research associate at the Vancouver Aquarium, an adjunct professor with the Marine Mammal Unit at the University of British Columbia, and she teaches biology at Vancouver Island University. Jane has spent the last 25 years studying sea otters and kelp on the west coast of Vancouver Island. She completed her B.Sc. at the University of British Columbia in 1981, and her Ph.D. at the University of California at Santa Cruz in 1993. She grew up on the B.C. coast, and knew from a very early age that she wanted to be marine biologist.
Blog post submitted by Jonathan Hultquist, manager of public programs for the Vancouver Aquarium.