Sir David Attenborough highlights how vulnerable cold-water corals are to rapidly changing ocean conditions in a new film released during the COP26 Climate Conference.
As a contribution to the Climate Conference, scientists at University of Edinburgh have produced a short film explaining how cold-water corals are particularly vulnerable to the rapid acidification of the oceans caused by carbon dioxide emissions – a largely hidden impact of fossil fuel use.
Narrated by COP26 People’s Advocate, Sir David Attenborough, and featuring research from the iAtlantic and One Ocean Hub projects, this film also highlights the central role of the ocean when considering climate change impacts and mitigation.
Scotland is currently hosting the 26th UN Climate Change Conference of the Parties, also known as COP26. During the opening ceremony, Sir David Attenborough addressed world leaders and proclaimed “We must recapture billions of tons of carbon from the air. We must fix our sights on keeping one and a half degrees within reach.”
This is particularly vital for the oceans most delicate of ecosystems, cold-water coral reefs.
Cold-water corals can form complex deep-sea reefs in many parts of the world. The closest cold-water coral reef to those negotiating in Glasgow is the Mingulay Reef Complex in the Sea of the Hebrides. Here at 100-200 m depth the reefs are formed by a species of calcifying coral called Lophelia pertusa, which creates its skeleton from a limestone mineral known as aragonite.
Ocean acidification, caused by carbon dioxide emissions dissolving into the ocean, is causing the aragonite saturation horizon (the depth that dead corals start to dissolve) to become shallower and shallower, leaving many reefs in water that is corrosive to their skeletons. These reefs are supported entirely by dead coral skeletons, and as that corrodes, the entire reef structure becomes unstable.
Professor Murray Roberts (Professor of Applied Marine Biology & Ecology at the University of Edinburgh and iAtlantic Project Coordinator) said “Cold-water coral reefs are the cities of the deep sea. They’re home for thousands of other species. But their skeletons are particularly vulnerable to changing ocean acidity. As the oceans of the world take up more carbon dioxide they are becoming more acidic and this is eating away at the foundations of the reefs. Lose the corals and the cities crumble.”
A research team led by the University of Edinburgh have exposed L. pertusa to present and predicted future ocean conditions. Dr Sebastian Hennige (Senior Lecturer in Marine Biology) said “By carrying out this study with both live and dead corals, we can now understand how ocean acidification will affect deep-sea coral reefs. By using detailed synchrotron imaging techniques, we are looking at the microstructure of the coral and discovering that dead coral skeletons become porous. This means that the vast, load-bearing structure of these reefs could crumble, causing the collapse of these precious ecosystems.”
The iAtlantic project is carrying out a health check of Atlantic marine ecosystems, including cold-water corals, and using the results to create better management strategies for their long-term sustainable use.
While over the last twenty years huge efforts have been made to conserve cold-water corals by created protected areas, many of these areas are in places that will become too acidic for corals before the end of the 21st century. Professor Murray Roberts said “We should think of cold-water corals like canaries in a coal mine when it comes to understanding the implications of ocean acidification. They are early warning indicators that we’ve got a problem and the only solution is to reduce our carbon dioxide emissions as quickly as possible, minimise the other stressors and work to restore corals in areas where they used to flourish.”
Sir David made this point clear in his address to the World Leaders Summit. We know how to reverse the damage done, and this film highlights just how important it is that we take that action.
The new film premiered at a special evening event hosted at Dynamic Earth in Edinburgh on Saturday 6 November, which highlighted the crucial role that the ocean plays in the climate crisis.
Research paper: Crumbling Reefs and Cold-Water Coral Habitat Loss in a Future Ocean: Evidence of “Coralporosis” as an Indicator of Habitat Integrity www.frontiersin.org/articles/10.3389/fmars.2020.00668/full
Research paper: “Cold-water corals in a changing ocean” https://www.sciencedirect.com/science/article/abs/pii/S1877343514000050?via%3Dihub