Coral reef structures resistant to Ocean Acidification

Coral reefs are structurally complex and "cemented" together by Crustose Coralline Algae.

Coral reefs are structurally complex and “cemented” together by Crustose Coralline Algae.

Unlike some of the media coverage, I’m not saying that coral reefs will be resistant to ocean acidification, and I’m certainly not saying that corals will be. There is some good news for the gloom of ocean acidification. Yet, the devil is in the detail!

Unknown to most people, Crustose Coralline Algae (known in the field as CCA to stop us tripping over the long name) are the pink algae which cement together the matrix of coral reefs the world over, effectively solidifying the structure that we know as “coral” reefs. These CCAs also form a dense, concrete like ridge on the exposed side of most reefs, protecting the more fragile corals from destructive wave energy. So, from a reef perspective they are very important.

Until now, most of the research into the future of CCAs under ocean acidification has demonstrated that they are likely to dissolve (e.g. Tropical species and temperate species). However, some colleagues and I have recently discovered two important things about these CCAs, (1) that they contain dolomite, a rather robust mineral that most people associate with mountains in Italy; and (2) that dolomite is quite resistant to pH which we are expecting in the world’s oceans in the next 100 years (link to the paper here).

What does this mean? Unfortunately it doesn’t mean that the world’s coral reefs are going to be saved from ocean acidification by dolomite-rich CCA. By all accounts the corals are still in trouble (though I still have my hopes for more adaptive capacity than we give them credit for!). However, there is some hope, because these CCA are likely to maintain their structure and thus continue to protect reefs from damage by waves.