Ocean acidification may be worse in B.C.’s ‘protected’ waters than along the outer coast.
A new study shows water in the Strait of Georgia is far more acidic than the water washing into it from the outer shelf—a finding that is likely true for B.C.’s many other fjords and sheltered river mouths.
It’s an unwelcome surprise, says Debby Ianson, an oceanographer with Fisheries and Oceans Canada who led the study.
“For shellfish farmers and others who may have been looking at the work published on the outer coast and saying, ‘Wow, these conditions get bad,’ conditions are much worse in the Strait of Georgia.”
Ianson’s team did gather data closer to Haida Gwaii, and will publish those results soon.
Because the Hecate Strait is more open than the Strait of Georgia, Ianson said carbon levels in Haida Gwaii waters are more similar to the outer coast.
The Strait of Georgia study is the first attempt to precisely map the dissolved carbon anywhere in B.C. coastal waters.
Aside from raising acidity, adding CO2 to the ocean robs shellfish and other marine calcifiers of aragonite and calcite—the stuff they need to make shells, coral, exoskeletons, or the internal ‘scaffolding’ inside many seaweeds.
“If you’re an organism that makes your shell out of aragonite, it means your shell is going to start to dissolve and you’re going to have to put a lot of energy out to rebuild it,” said Ianson, noting that other studies already show a decline of some key calcifiers in B.C. waters, including the tiny pteropod, or ‘sea butterfly,’ that makes up much of the diet for juvenile Pink salmon.
Ianson said one reason the Strait of Georgia study is so surprising is that it shows the strait may be protected from low-oxygen, but not from high CO2.