“The overall big picture here is that surface water carbon dioxide levels are indeed increasing in the Gulf of Mexico (except in the central Gulf) and human activities are contributing to this acidification,” says Shamberger. “Also, coastal acidification is occurring faster than open ocean acidification, which is especially troubling for coastal coral reef and shellfish ecosystems that support many important fisheries species.”
The ocean absorbs carbon dioxide from the atmosphere, which reduces pH levels and concentrations of calcium carbonate, a mineral used by shellfish to calcify their shells. As more carbon is released into the atmosphere, concentrations of calcium carbonate decrease and the shells of organisms like foraminifera get thinner, a trend Osborne saw clearly in the sediment cores she examined.
“The shell thickness record instantly showed a long-term declining trend,” she said. “It was really obvious across entire record.”
Research published this week in the peer-reviewed journal Science analyzed more than 100,000 seawater samples worldwide collected from 1994 to 2007 and taken from nearly every corner and depth of ocean.
The analysis found the oceans are absorbing about 31 percent of the carbon humans are spewing into the world. For context, the weight of the carbon seeping into the ocean each year, on average for the period of study, is roughly equivalent to 2.6 billion Volkswagen Beetle cars, Feely said.
As the Pacific Ocean acidifies—a consequence of carbon emissions—oyster farms off California, Washington State, and British Columbia have struggled to get larvae to grow into seed, the stage when young oysters’ shells have formed. Though scientists are not quite sure why, the water off Southeast Alaska hasn’t seen the same deleterious effects. Now, entrepreneurs and investors are eyeing the state, looking to turn a profit off the short-lived gains of climate change.
It’s a calamity that threatens Washington state’s $270-million-a-year shellfish industry. And it has the Taylors — after a century-plus producing shellfish in the Evergreen State — exploring every potential angle to steel their mollusks against the corrosive effects of ocean acidification.