Slumping: a soft-coral threat

Ko ​Myeong-hyo loved the vibrant colour and thriving life of South Korea‘s soft corals when she first began diving off the coast of Jeju island six years ‌ago, looking to harvest seafood for sale. “Watching the coral garden collapse and turn white, it was so ​disorienting,” Ko says now, after two years of rising temperatures and harsher weather brought by climate change have led ⁠to many corals slumping over and dying. “I was afraid the whole sea might be collapsing.”

The 'slumping’ phenomenon is showing up again this year, says the Paran Ocean Citizen Science Centre, a group of divers who monitor the island’s UNESCO-listed soft corals, mostly around uninhabited islets south of Jeju. Unlike hard corals supported by rigid calcium carbonate skeletons, soft corals rely on internal fluid pressure to keep upright. Environmental changes can disrupt that ‌pressure, leading them to slump or collapse.