A law passed by the Maine Legislature will establish a commission to study and address the negative effects of ocean acidification on shellfish grounds and other ecosystems. Supporters of the law called it the first of its kind on the East Coast. It took effect Wednesday. The commission will include fishermen, aquaculturists, scientists, and legislators. Representative Mick Devin, a Democrat who sponsored the bill, said the commission will look for ways to protect the state’s marine resources and economy. Supporters of the law say ocean acidity levels have increased by 30 percent over the past two centuries. They fear that acidification could cause losses to Maine’s shellfish industry if left unchecked.