Coral helper stays robust under ocean acidification

Researchers from the ARC Centre of Excellence for Coral Reef Studies at The University of Western Australia (Coral CoE at UWA) and the Victoria University of Wellington have found Crustose Coralline Algae, crucial to the survival of coral reefs, may be able to resist the impacts of ocean acidification caused by climate change.

The findings are important to develop understanding of how longer-lived species, such as tropical corals, can respond over multiple generations to ocean acidification.

The scientists found coralline algae was able to build tolerance to ocean acidification took, on average, six generations about six to eight weeks each to develop resistance to ocean acidification.

UWA Professor Malcolm McCulloch, Coral CoE Deputy Director, who led the research group said coralline algae was vital for the survival of coral reefs and many ocean species.

“Crustose coralline algae bind coral reefs together – without it, coral reefs as we know them today wouldn’t exist,” Professor McCulloch said.

“They also limit erosion in reefs that are often made up of mainly coral fragments and act as a nursery for many marine species. They are the main player in temperate reef formation along the Australian and New Zealand coastlines.”

Victoria University of Wellington lead author Dr Christopher Cornwall said coralline algae went through a natural process of calcification, where it built a crustose-like calcium carbonate skeleton.

“Skeletons like this provide structure, allowing them to grow, as well as providing a substrate for other organisms such as other coral to grow upon,” he said.

“Our research has showed for the first time that while growth of these skeletons is initially susceptible to the effects of ocean acidification caused by increased CO2, over multiple generations they develop resistance.

“Coralline algae are a useful model species to test hypotheses about adaptation or acclimation over time as they grow to maturity in six weeks as opposed to several years for many coral species.”

The research focused on tropical coralline algae species from northern Australia, so the next step is to study temperate species—like those in southern Australian and New Zealand waters—that grow a lot slower and may not acclimatise to climate change as quickly.