Ocean Acidification’s Effect on Crab Studied

Studies by federal fisheries researchers are documenting the
affects ocean acidification are having on Alaska’s crab fisheries and the
potential for all waters in Alaska to be in a corrosive situation for the year
2100. The big unanswered question, says Bob Foy, who oversees the shellfish assessment
program at the Alaska Fisheries Science Center in Kodiak, is whether the crab
can adapt in time.
Foy told an audience packed into a forum at ComFish 2016 in
Kodiak on April 1 that the probability of crab being able to adapt is very
high, but the question is whether they can adapt at the speed that ocean
acidification is increasing in the Bering Sea.
Foy, with Chris Long and Katherine Swiney, all at AFSC in
Kodiak, are leading studies there on the impact of climate change and ocean
acidification on shellfish.
Colder water holds more carbon dioxide, Foy said. Absorption
of carbon dioxide into the ocean makes the sea water more acidic. The carbon
dioxide binds with carbonate ions, so that the carbonate ion is no longer
available to help corals and shellfish build shells. That carbonate ion is the
shell-building organism that combines calcium and carbonate together to
precipitate the shell, and if there is not enough carbonate in the seawater, it
makes that process more difficult, he said.
The decreased pH level of the waters of the Bering Sea is
already associated with smaller crab eggs and embryos and larger yolks in the
eggs, and as the pH of seawater there has decreased, so has the survival rate
of juvenile crab.

Foy and his team are continuing to monitor ocean
acidification, to better understand species-specific physiological responses to
it, while other AFSC researchers are studying the potential impact of ocean
acidification on rock sole and Alaska pollock.