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Global warming has devastating effect on corals

Global warming has had a more devastating effect on some of the world’s finest coral reefs than previously thought, a new study suggests. An international team of researchers, led by the University of Newcastle upon Tyne, surveyed 21 sites and over 50,000 square metres of coral reefs in the inner islands of the Seychelles in 1994 and 2005.Their report is the first to show the long-term impact of the 1998 event where global warming caused Indian Ocean surface temperatures to increase to unprecedented and sustained levels, killing off (or ‘bleaching’) more than 90 per cent of the inner Seychelles coral. The research showed that, while the 1998 event was devastating in the short term, the main long-term impacts are down to the damaged reefs being largely unable to reseed and recover. Many simply collapsed into rubble which became covered by unsightly algae.The collapse of the reefs removed food and shelter from predators for a large and diverse amount of marine life - in 2005 average coral cover in the area surveyed was just 7.5 per cent. The survey also revealed that species diversity of the fish community had decreased by 50 per cent in the heavily impacted sites. Smaller fish have reduced in number more quickly than larger species but their decreased availability has started to have a more lasting effect on the food chain, and this effect is likely to be amplified as time goes on. Moreover, the observed decrease in herbivorous fish is a key concern as they control algal spread.Lead researcher Nick Graham, of Newcastle University’s School of Marine Science and Technology, said: “We have shown there has been very little recovery in the reef system of the inner Seychelles islands for seven years after the 1998 coral bleaching event. “Reefs can sometimes recover after disturbances, but we have shown that after severe bleaching events, collapse in the physical structure of the reef results in profound impacts on other organisms in the ecosystem and greatly impedes the likelihood of recovery. “Unfortunately it may be too late to save many of these reefs but this research shows the importance of countries tackling greenhouse gas emissions and trying to reduce global warming and its effect on some of the world’s finest and most diverse wildlife.“The team’s findings were published yesterday in the Proceedings of the National Academy of Sciences.

This was posted in Bdaily's Members' News section by Ruth Mitchell .