Sea otters help keep oceans healthy

2012-09-12 12:39
Sea otters are warding off the accumulation of acidic carbon dioxide in Alaska's waters by preying on sea urchins. (Reed Saxon, AP)

Sea otters are warding off the accumulation of acidic carbon dioxide in Alaska's waters by preying on sea urchins. (Reed Saxon, AP)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

Anchorage - Sea otters are warding off the accumulation of acidic carbon dioxide in Alaska's waters by preying on sea urchins that feed on underwater kelp beds vital to the oceans' health, according to a study.

Otter-protected kelp beds absorb about 12 times as much carbon dioxide during photosynthesis as thinned-out kelp beds, according to a study published in the September issue of Frontiers in Ecology and the Environment.

Atmospheric carbon dioxide threatens marine environments because the gas, when absorbed into the ocean, increases acidity levels, causing the phenomenon known as "ocean acidification", according to scientists. So by devouring sea urchins, otters allow the kelp to grow and keep the oceans cleaner.

Urchin-eating sea otters produce a significant savings, according to the study's authors, who said it would cost between $205m to $408m to offset the carbon that sea otters enable kelp beds to absorb, based on prices used in the European Carbon Exchange.

The study relied on data collected over 40 years from sites between British Columbia, Canada, and Alaska's Aleutian Islands.

Near extinction

Co-author Jim Estes said he hopes the study will help people understand that sea otters have far-reaching benefits.

"On the one side, people like sea otters because they're fuzzy, cool things. On the other side, a lot of people hate them," said Estes, a biologist and sea-otter expert at the University of California at Santa Cruz.

Fishermen, including shellfish harvesters, "are, without question, significant competitors" and famously hostile to sea otters, Estes said.

But by preserving kelp forests, otters benefit fishermen because kelp beds provide an important fish habitat, he said.

Sea otters were once hunted nearly to extinction, victims of a commercial harvest that started with czarist Russia's colonisation of Alaska. A 1911 treaty ended the commercial hunt and numbers rebounded.

But the population of sea otters from Kodiak, Alaska, to the western Aleutian Islands has dropped sharply in recent years, declining as much as 67% since the mid-1980s, according to the US Fish and Wildlife Service.

In 2005, the western Alaska otter population was listed as threatened under the Endangered Species Act, with the steepest population drop in the state's Aleutian Islands.

Estes said many scientists studying Alaska's sea otters believe predation by killer whales is the main reason for the recent decline. Whales have increasingly preyed on otters as Steller sea lions and seals have become scarce, Estes said.

The 1989 Exxon Valdez oil spill also killed thousands of sea otters, up to 40% of the population in western Prince William Sound, according to state and federal scientists. The otter population has not fully recovered in spill-affected areas, scientists say.

Join the conversation! encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.
Read more on:    climate change  |  marine life

linking and moving

2015-04-22 07:36 publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
Comments have been closed for this article.

Inside News24


Rugby World Cup 2015

All the action from the 2015 RWC, including live coverage of all 48 matches, breaking news, fixtures, results, logs - and much more!


Rugby World Cup 2015

Japan victory attracts record TV figures
iPads the secret to Japanese RWC success
Georgia desperate for Namibian win
England's early exit bad for RWC business
Traffic Alerts

It is time to focus on your daily rhythm. Are you putting too much attention on future projects and neglecting the day to more

There are new stories on the homepage. Click here to see them.


Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire network.


Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.