How will climate change impact cold-water corals? Mostly through food loss, study says

Large colony of the cold-water coral Lophelia pertusa colonised by crinoids and soft corals at 700 m water depth (Porcupine Seabight, Irish continental margin). Credit ROV image: MARUM ROV Cherokee, Bremen, Germany.
  • A new study warns that cold-water corals, also known as deep-water corals, could be most impacted by a decrease in food supply as climate change shifts the dynamics of the planet’s oceans.
  • The authors came to this conclusion by examining how cold-water corals survived the last major period of global warming that occurred at the end of the last glacial period and the start of the current interglacial period, which is somewhat analogous to how the Earth is projected to warm by the end of this century.
  • However, experts point out that cold-water corals today are subjected to a number of additional stressors, including ocean acidification, destructive fishing practices, and pollution, and that the climate is changing far more rapidly than it did in the past.
  • Cold-water corals are considered to be equally important — or perhaps even more important — than tropical corals, which makes understanding their chances of survival of the utmost importance, researchers say.

Between 1869 and 1870, the H.M.S. Porcupine sailed into the North Atlantic Ocean and scraped a dredge along the seafloor. When the sailors pulled the dredge back to the surface, it held pieces of stony coral that lived in the cold, sunless depths of the sea.

Examining the coral back on land, English paleontologist Peter Martin Duncan noted in a report, with some wonder, that these corals could live as easily in the deep, cold ocean as well as other organisms could in the warmer, shallower parts of the sea. “It suggests that a great number of the Invertebrata are not much affected by temperature,” he said, “and that the supply of food is the most important matter in their economy.”

Today, the ocean is a very different place than what it was when the H.M.S. Porcupine set sail. Climate change is causing global ocean temperatures to rapidly rise, while lowering oxygen levels and acidifying the water. The seas are also being damaged by overfishing, pollution, and other human activities like transportation. But according to a new study published in PLOS Biology, the biggest threat to cold-water corals, like the ones scooped up by the H.M.S. Porcupine all those years ago, is a lack of food. As it turns out, Duncan’s observations appeared to be correct.

Elizabeth Claire Alberts, Mongabay, 1 June 2022. Press release.

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