A DOUBLE whammy of disease and global warming has flattened Caribbean coral reefs in just 40 years. Consequently, the reefs have lost the intricate, tree-like surface corals that provided sanctuary for reef fish and other creatures up to the 1970s, as well as protecting coastlines from the onslaught of waves.
鈥淭he importance of this complexity is both for biodiversity and for coastal protection,鈥� says of the University of East Anglia, UK.
Gill and her colleagues analysed 40 years of data from 500 surveys of 200 Caribbean reefs. They discovered that the flattening took place in two main phases. The first, in the late 1970s, saw white-band disease sweep through the reefs, killing 90 per cent of the most spectacular tree-like and staghorn coral species (Proceedings of the Royal Society B, ).
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In the second phase, in 1998, many remaining tree-like corals were wiped out in a massive bleaching event, probably driven by global warming. Large, weedy corals took over, outcompeting the remaining tree-like corals.
Flat reefs now cover 75 per cent of the Caribbean, compared with just 20 per cent in the 1970s. 鈥淚t鈥檚 difficult to see how to reverse any of this,鈥� says Gill. The biggest problem, she says, is the sheer density of human population 鈥� stresses on the coral include pollution and tourism. By contrast, reefs remain almost pristine across the Indian Pacific, where human habitation is sparse.