Ocean acidification resulting from human emissions of carbon dioxide has already lowered and will further lower surface ocean pH. The consequent decrease in calcium carbonate saturation potentially threatens calcareous marine organisms. Among these organisms, shellfish are very important species of a great ecological and also economical value. This paper reviews several reportson the effects of acidification on mollusc species. While numerous studies have shown a significant impact of decreasing seawater pH on shellfish growth and health, most of these studies considered a decrease in pH much higher than the one projected for the end of the century (-0.4 unit). Within this range (8.1-7.7), it appears that acidification does not have a dramatic effect on these species at least over few weeks exposure. However, several studies showed an alteration of metabolic rates and health of these organisms which could be related to shell dissolution and could cause significant loss over longer time-scales. It is therefore of utmost importance to carefully assess the relationship between shellfish calcification/dissolution rates and seawater saturation state with respect to calcium carbonate.
Gazeau F., 2008. Impact of ocean acidification on marine shellfish. In: Briand F. (Ed.), Impacts of acidification on biological, chemical and physical systems in the Mediterranean and Black Seas, pp. 81-87. Monaco: CIESM. Article.
