Indonesia’s devastating wildfires of 1997 may have killed off an ecologically significant coral reef. Researchers in Australia say that smoke from the fires triggered a red tide that suffocated the Mentawai Island reef off the coast of Sumatra.
Nerilie Abram of the Australian National University Research School of Earth Sciences and colleagues report in this week’s Science that wildfire smoke settled round the reef, bringing iron to the water’s surface. The boost in iron led to an explosion of phytoplankton, known as a red tide, which then asphyxiated the corals with dead biomass.
The finding is just one chapter in a long history of human damage to reefs, which another team of researchers, also writing in Science, says extends back to the hunter-gatherer period. John Pandolfi at the Smithsonian National Museum of Natural History and colleagues put together the ecological histories of 14 coral reefs round the world. They found that most of the reefs were substantially degraded before 1900, often by overfishing. More recently, bouts of bleaching and disease have brought many reefs to the brink of death.
The team concludes that even without these new threats, most reefs are doomed without an immediate halt to human damage. Even the best-protected of them, in Australia’s Great Barrier Reef, are up to a third of the way to ecological extinction.