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Melting shells of the sea butterflies – a sign of global warming endangering oceans

You Know the Ocean’s in Trouble When Your Shell Starts Melting http://www.enn.com/wildlife/article/47393 Things are getting really dicey for a little ocean creature called a pteropod. Better known as the “sea butterfly,” this delicate little sea snail is serving as an unfortunate bellwether of the deteriorating state of our oceans. Why? Conditions in the Antarctic ocean and along the West Coast of the U.S. have become so unnaturally acidic that the shells of sea butterflies are literally dissolving away.

“We did not expect to see pteropods being affected to this extent in our coastal region for several decades,” said Dr. William Peterson, an oceanographer at National Oceanic and Atmospheric Administration (NOAA)’s Northwest Fisheries Science Center, in a NOAA press release.

Damage that’s “several decades” early is a big alarm bell. We’d better pay close attention before it’s too late.

What We’re Doing to Our Oceans

The chemistry of the world’s oceans is changing, thanks to the carbon dioxide humans continue to spew into our atmosphere. Oceans absorb between one quarter to one third of that carbon dioxide. Over time, it has turned the ocean from a slightly alkaline state to a bit more acidic.

According to some estimates, the ocean’s pH level 150 years ago was about 8.2. It’s now about 8.1. It may seem to be an infinitesimal shift, but it’s worse than it sounds. The more acidic the ocean gets, the harder it is for marine life like oysters, clams and corals to form calcium carbonite skeletons and shells.

In the case of pteropods, the increased acidity of the ocean is actually eating away at their shells.

“The first thing that happens is the dissolution of their shell,” NOAA’s Dr. Nina Bednarsek told PBS. “Dissolution can be mild, [to] very severe. Once you have it dissolving on the outside, you have to put so much more energy into the shell in order to maintain it. The energy that you would otherwise use for other important physiological maintenance you are putting in the shell maintenance.”

Researchers working off the coast of Oregon, Washington and California in 2011 discovered that over half of the sea butterflies they found onshore were victims of “severe dissolution damage.” Offshore, about 24 percent were damaged.

If we don’t change our ways, by 2050, researchers estimate that coastal waters will be 70 percent more acidic than they were in the pre-industrial era.

Continue reading at ENN affiliate, Care2.

May 16, 2014 - Posted by Christina Macpherson | climate change, oceans, USA