An acidic ocean threatens shellfish farms

Posted on EPOCA: 31 Oct 2011

 For more than two decades, Rob Saunders grew his shellfish larvae in ordinary seawater drawn from the pristine natural environment of Baynes Sound, one of the most productive shellfish farming areas on B.C.’s West Coast.

Now the water in Baynes Sound is so acidic, Mr. Saunders’ fragile seed stock will die unless he artificially adjusts the PH level in his hatchery tanks.

“Because of ocean acidification the only way we can grow any larvae – oysters, clams, mussels, geoducks, you name it – is to take the CO2 out of the seawater,” said Mr. Saunders, CEO of Island Scallops, the largest producer of shellfish seed stock on province’s West Coast.

“We would have been out of business this year if we didn’t figure out how to solve the problem.”

Ocean acidification, a worldwide phenomenon linked to global warming, was identified as a serious threat to the shellfish industry in Oregon and Washington state five years ago.

Caused by the absorption of excess CO2 from the atmosphere, ocean acidification lowers ocean PH levels and reduces the concentration of calcium carbonate, a key building block of seashells and other marine skeletons.

Mr. Saunders is currently taking part in a two-year, $250,000 study of pH levels in the waters between Denman Island and Vancouver Island, about 20 kilometres south of Courtenay.

Funded by the federal Department of Fisheries and Oceans, the study involves rigorous daily testing using an infrared gas analyzer to detect ocean carbon dioxide. DFO officials refused to discuss data that has been gathered so far, saying preliminary results won’t be made public until sometime next spring.

However, Mr. Saunders said there’s no doubt that acidification is affecting the survival of shellfish larvae.

“We grow them under different concentrations of CO2 to see how they live and die,” he said. “And they die if we use the ocean water. Period.”

The changes are not yet severe enough to affect bivalves that have already formed their shells, he added.

Still, ocean acidification is a top priority for biologists at the recently opened Deep Bay Marine Field Station, an $8.5-million shellfish research, development and training centre a few kilometres from Mr. Saunders’s scallop farm.

“It’s a complex issue that could have major repercussions for the west coast shellfish industry, but it’s only come to our attention in the last few years,” said Brian Kingzett, manager of the Deep Bay facility. “We’re just beginning to study it.”

Brennan Clarke, The Globe and Mail, 30 October 2011. Article.