Acidification, climate change killing off corals

Ocean acidification and rising temperatures are gradually killing off the biggest and most robust corals on the Great Barrier Reef since 1990, the “tipping point” year, says a new study. The study, authored by Australian Institute of Marine Science (AIMS) scientists Glenn De’ath, Janice Lough and Katharina Fabricius, is the most comprehensive one to date on calcification rates of Great Barrier Reef (GBR) corals. Calcification is how much skeleton the coral puts down each year. Reef corals create their hard skeletons from materials dissolved in seawater. When large amounts of atmospheric carbon dioxide enter seawater, the resulting chemical changes effectively reduce the ability of marine organisms to form skeletons. The findings are based on rigorous statistical analyses of annual growth bands from 328 Porites corals from 69 reefs across the length and breadth of the GBR, and extending back in time up to 400 years. The data are from AIMS Coral Core Archive (ACCA), the most extensive such collection in the world, said an AIMS release. “It is cause for extreme concern that such changes are already evident, with the relatively modest climate changes observed to date, in the world’s best protected and managed coral reef ecosystem,” according to AIMS scientist Janice Lough. … The Economic Times, 5 January 2009. Full article.