Sea otters fight climate change by guarding kelp forests

Sea otters fight climate change by guarding kelp forests

Floating on their backs, flippers up, massaging their round faces with fuzzy front paws, it’s hard not to be completely enamored with sea otters. They are cute, playful, and really do hold onto each other at night to prevent themselves from drifting away while they sleep. With all this charm, there’s even more reason to love this species, they play a vital role in the balance of their ecosystems. Like African forest elephants and beavers, sea otters are considered a keystone species, meaning other species largely depend on and are influenced by their behavior.

Another image that comes to mind when one thinks of sea otters, is how lounging on their backs they delightfully munch on crabs, barnacles, or sea urchins. It is this diet that trickles into a C02 storage machine. Having a meal plan rich in crustaceans keeps these populations in check. Too many crabs burrowing into the submerged, muddy banks would make them unstable. Secure sloughs provide structure and create habitats for other species to live in like slugs, algae, and kelp forests. 

Otter snacking on sea urchins. Image credit: Katherine Johns

Not only do sea otters contribute to the foundation in which these underwater forests grow, but they also remove and scare their top predator, the sea urchin. These spiky, globular echinoderms eat the roots and cut the remaining plant off from receiving essential sediment nutrients. They also multiply rapidly, sweeping across the ocean floor and devouring entire stands of kelp. When sea otters are around, they reduce the urchin population and frighten the creatures from advancing on the forests — choosing instead to hide away and wait for pieces of kelp debris to fall. 

The effect otters have on kelp is what takes their keystone species status to a global level. Kelp forests are one of the most efficient absorbers of CO2,​ ​using carbon from the atmosphere to grow leafy structures underwater. With the protection sea otters provide, these forests flourish. Kelp forests that are guarded by sea otters can sequester up to 12 times more carbon from the environment.

Underwater kelp forest. Image credit: Heal the Bay, Creative Commons

Researchers have found that the presence of sea otters increases kelp forest carbon storage from 4.4 to 8.7 megatons annually. To put that in perspective, it would take 3 to 6 million passenger cars removed from the road to equal that amount. As more money is being invested into carbon capture technology, scientists like Chris Wilmers and Jim Estez from the University of California at Santa Cruz advocate that more value should be placed on protecting and restoring sea otter populations as a natural climate change solution. Using the current price on the European carbon market, the amount stored by kelp forests and reinforced by sea otters would be worth $205-$400 million. Such mitigation of global greenhouse gasses makes these cuddly creatures all the more lovable. 

Image credit: Ingrid Taylar, Creative Commons

Yet, despite their appeal and importance in our ecosystem, sea otters are highly endangered. Habitat degradation, oil spills, net fishing, and the fur trade are major factors in their decline. The species is believed to have been reduced by over 50 percent in the last 45 years. Reclaiming their historical range and numbers will help keep the kelp forests thriving and sequestering more carbon from the environment. Sea otters, and their role in helping to regulate the ocean carbon cycle, are further proof that protecting Earth's wildlife is key to combating the climate crisis.