[Marine Science Laboratory, School of Biological Sciences, Universiti Sains Malaysia]

Bivalve aquaculture in South East Asia is mainly based on oysters, mussels and blood cockles, followed by scallops, clams, and ark shells. The total production has increased gradually from 1990 to 2002 but been decreasing since 2002. Ocean acidification is predicted to decrease the calcification rate in molluscs inclusive of bivalves, which hinders skeleton growth. This may have been negatively affecting the efficiency of bivalve aquaculture in diverse ways interacting with other factors. To date, most studies in this regard were focused on physical and chemical parameters such as aragonite levels, partial pressure of carbon dioxide and total alkalinity. Only few studies have, however, examined quantitative responses to the recognized level of ocean acidification in physiology or ecology. In practice, changes in ecological traits in the culturing field would be gradual and incremental, which may not be simply ascribable to the acidification in short terms. Explicit studies on the long-term responses of populations of shelled species to changes in ocean acidity are crucially important in order to sustain aquaculture for adequate food production.