Read here. Multiple peer-reviewed studies examine ocean acidification issue.
"There have been more than enough speculative predictions of catastrophic negative impacts due to the ongoing rise in the air's CO2 content with regard to the ability of earth's oceans to sustain their many different lifeforms, as well as impassioned calls for immediate actions to reduce anthropogenic CO2 emissions, when for all we currently know, elevated atmospheric CO2 concentrations could well prove to be a net benefit to the marine biosphere, just as they are a huge blessing to earth's terrestrial lifeforms."