Some Corals Grow After ‘Fatal’ Warming

An anonymous reader quotes a report from Phys.Org: For the first time ever, scientists have found corals that were thought to have been killed by heat stress have recovered, a glimmer of hope for the world’s climate change-threatened reefs. The chance discovery, made by Diego K. Kersting from the Freie University of Berlin and the University of Barcelona during diving expeditions in the Spanish Mediterranean, was reported in the journal Science Advances on Wednesday. Kersting and co-author Cristina Linares have been carrying out long-term monitoring of 243 colonies of the endangered reef-builder coral Cladocora caespitosa since 2002, allowing them to describe in previous papers recurring warming-related mass mortalities. [T]he researchers found that in 38 percent of the impacted colonies, the polyps had devised a survival strategy: shrinking their dimensions, partly abandoning their original skeleton, and gradually, over a period of several years, growing back and starting a new skeleton. They were then able to gradually re-colonize dead areas through budding. “Coral are made up of hundreds to thousands of tiny creatures called polyps that secrete a hard outer skeleton of calcium carbonate (limestone) and attach themselves to the ocean floor,” the report mentions. In order to be sure that the polyps were the same animals staging a comeback, “the team used 3D computer imaging to confirm the old, abandoned skeleton was connected to the new structure.” “This process of ‘rejuvenescence’ was known to exist in the fossil record but had never before been observed in coral colonies that exist today.” While further investigation is required, the team says the findings open up the possibility that other modern corals around the world might be apply similar strategies to survive.