Coral reefs can’t return from acid trip

A new study published in Nature Climate Change finds coral reefs are under threat from ocean acidification.

The study was led by researchers from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE). Their results suggest some corals and coralline algae — the ‘glue’ that holds reefs together — cannot survive the expected more acidic oceans caused by climate change.

« The results validate previous research on ocean acidification threats to coral reefs, » said lead author Dr Steeve Comeau, who is now based at the Sorbonne Université CNRS Laboratoire d’Océanographie de Villefranche sur Mer in France.

Co-author Prof Malcolm McCulloch, from Coral CoE at the University of Western Australia, said the researchers examined the calcifying fluid of four species of coral and two types of coralline algae under a year-long simulation.

« The effects on the calcifying fluid were rapid and persisted for the whole year, » Prof McCulloch said.

Co-author Dr Chris Cornwall, now at the Victoria University of Wellington in New Zealand, explained coralline algae cements reefs together by acting as a foundation species and breeding ground for many species from the poles to the tropics.

« Declines in coralline algae could lead to the loss of important marine species that use the algae as a nursery, » he explained.

« The results also confirm that ocean acidification could have repercussions on the competition between species. This can affect the ecological function of reefs, » Dr Comeau added.

He said the team did find two coral species were resistant to ocean acidification. However, these are corals that were resistant from the start.

« This indicates they already had an in-built mechanism that made them resistant, » he explained, « whereas sensitive corals were affected from the start and were not actually able to acclimatise. »

The study suggests the composition and function of future reefs — if they can survive climate change — will be very different to what we see today.

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Materials provided by ARC Centre of Excellence for Coral Reef Studies. Note: Content may be edited for style and length.