It didn’t take long for researchers examining the tiny sea snails to see something amiss.

The surface of some of their thin outer shells looked as if they had been etched by a solvent. Others were deeply pitted and pocked.

These translucent sea butterflies known as pteropods, which provide food for salmon, herring and other fish, hadn’t been burned in some horrific lab accident.

They were being eaten away by the Pacific Ocean.

For the first time, scientists have documented that souring seas caused by carbon-dioxide emissions are dissolving pteropods in the wild right now along the U.S. West Coast. That is damaging a potentially important link in the marine food web far sooner than expected.

“What we found was just amazing to us,” said Richard Feely, a scientist with the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory, who helped collect the live samples. “We did the most thorough analysis that’s ever been done and found extensive impacts on marine life in the field from ocean acidification.”

This is the broadest and most detailed indication ever that acidification is already damaging native creatures in the wild. It raises many new questions about whether other sea life, too, might already be harmed — directly by acidifying seas, or by subtle shifts in parts of the food chain.

“These changes are happening years earlier than we had projected,” said Nina Bednarsek, a research fellow with NOAA who inspected the pteropods to identify shell scarring. “It is really a first indication of what is going on in our ecosystem.”

The smooth shell of a healthy pteropod is seen at left. The pteropod in the center was exposed to elevated CO2 conditions in a laboratory, to mimic conditions researchers saw in the wild. And at right, a shell with holes and pits, also produced by laboratory conditions, corresponds to some of the most extreme damage scientists expect to see with elevated CO2.

Feely and others already had documented that sea chemistry in many areas off the West Coast, particularly in the Pacific Northwest and Northern California, was changing far faster than initially expected as oceans absorb ever moreCO2 from fossil fuels. They also had shown that this chemical change already has killed nonnative Northwest oyster larvae.

Now, they’ve found severe shell damage on more than half of the pteropods they collected from waters near shore between Central California and the Canadian border. The findings were published today in the British Journal “Proceedings of the Royal Society B.”

The shell damage corresponds so precisely to where chemical changes have hit the marine world hardest — specific coastal hot spots in Washington and Oregon, where water wells up from the deep on windy days — that NOAA scientists said they could clearly pinpoint the cause: atmospheric CO2.

Read the rest of this story on The Seattle Times online.