Coral and algae species subjected to more acidic seawater showed no acclimatisation to the new conditions for over a year, a new study has found, suggesting that vulnerable reefs may not be able adapt fast enough to cope with climate change.

With oceans absorbing about 22 million tonnes of carbon dioxide from the atmosphere a day, seas have already become about 30 per cent more acidic over the past two centuries.

Shell-forming creatures from oysters to types of plankton are increasingly at risk from the changes, which have been called the "evil twin" - along with higher temperatures - of climate change.

Research into coral reefs extends from studying how they cope with higher temperature to what happens when waters turn more acidic. Credit:Jason South

A team of scientists exposed four coral and two coralline, or calcifying algal, species to varying ocean acidity levels for a year at the Moorea reef in French Polynesia to test their responses.