How will corals respond to climate change? An EU-funded initiative has been studying the effect of changing carbon dioxide (CO2) levels on corals. Health © Shutterstock Climate change and the increase of CO2 levels are now recognised as a serious threat to corals and coral reefs. Scientists believe that rising levels of CO2 will result in the acidification of the world's oceans and seriously affect the growth of coral reefs, resulting in their decline. The 'Mediterranean coral calcification in response to global change' (MECCA) project has examined the effect of different CO2 levels on calcification rates, when coral tissues become hardened with deposits of calcium. Scientists have also investigated the role of coral-associated microorganisms in calcification and their response to changing conditions. Project partners have examined samples of live Mediterranean corals in the laboratory. The Mediterranean is an enclosed system that can be regarded as a miniature ocean. This body of water is expected to react faster to global change than the open sea. Coral samples were originally kept in aquaria, but they were found to be vulnerable to attack from parasites. As a result, the samples have been maintained in aerated vials and exposed to six different CO2/air mixtures including ambient air and air stripped of CO2. Results from the MECCA project enable scientists to determine the effect of rising CO2 levels on the calcification of corals and coral reefs. The work will support environmental policy decision-makers to take mitigating action.
