Superhero Sea Otters Save The Day

Sea otters can play a key role in reducing CO2 — in decreasing one of the main causes of global warming — according to a recent study.

In the September 7 Frontiers in Ecology and the Environment, University of California, Santa Cruz professors Chris Wilmers and James Estes describe how a “thriving sea otter (Enhydra lutris) population that keeps sea urchins in check will in turn allow kelp forests to prosper,” with huge consequences for the environment.

Sea urchins are kelp grazers who hide in crevices; when otters are present, the urchins feed on scraps. But in the absence of otters, urchins eat the kelp “voraciously.” Says Science Daily:

Kelp is particularly efficient at sequestering CO2 from the atmosphere through photosynthesis. CO2 concentration in the atmosphere has increased 40 percent since the beginning of the industrial revolution, causing global temperatures to rise, the authors write.

After reviewing 40 years of data on otters and kelp bloom in regions from Vancouver Island to the western edge of Alaska’s Aleutian Islands, Wilmers and Estes found that otters, by helping to control the urchin population, “undoubtedly have a strong influence” on how much CO2 is in the atmosphere.

Both scientists emphasized that spreading the otter population is not in and of itself enough to reduce the amount of CO2 in the atmosphere. The value of their research lies in how it suggests that “managing animal populations can affect ecosystems abilities to sequester carbon:”

“Right now, all the climate change models and proposed methods of sequestering carbon ignore animals,” Wilmers said. “But animals the world over, working in different ways to influence the carbon cycle, might actually have a large impact.

“If ecologists can get a better handle on what these impacts are, there might be opportunities for win-win conservation scenarios, whereby animal species are protected or enhanced, and carbon gets sequestered,” he said.

Wilmers and Estes have gone so far as to calculate that “the CO2 removed from the atmosphere via the otter-kelp link could be worth between $205 million and $408 million on the European Carbon Exchange.” They also speculate if it might be possible for those millions of dollars to be used to reintroduce and manage sea otter populations in areas where their numbers have drastically declined.

As Scientific American reports, another species of otter, the Japanese river otter (Lutra lutra whiteleyi), was recently declared extinct by Japan’s Ministry of the Environment. River otters once numbered in the millions but, after overhunting and the loss of their habitat to development and pollution, not a single one not been sighted in 30 years.

Not too long ago, sea otters faced a similar fate as they had been hunted nearly to the point of extinction. Wilmers’ and Estes’ study underscores how animals, in ways that we are just beginning to discover, can play a key role in the carbon cycle. One creature, small or large, can have far-reaching effects on the planet and the lives of all who dwell on it.

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