Marine biologists have identified the 10 most diverse and threatened coral reefs in the world, all of which will be extinct unless a concerted effort is launched to protect these highly vulnerable habitats.
A study by an international team of scientists has concluded that it is a myth to believe the oceans are so vast that they will largely escape the effects of human activities. Indeed, the coral reef "hotspots" are uniquely susceptible to environmental degradation.
Callum Roberts, of the University of York, said that the top 10 coral reefs accounted for a mere 0.017 per cent of the world's ocean environment, yet they were home to more than a third of the species of marine wildlife found in restricted ranges. The research by Dr Roberts' team,published today in the journal Science, was discussed at the annual meeting of the American Association for the Advancement of Science (AAAS) in Boston.
"More than a third of the species that are most at risk of dying out are living in these very small areas, which are themselves desperately vulnerable. It gives the lie to the idea that mankind cannot do much damage to the ocean," Dr Roberts said.
"We know that unless we take action right away, marine species will start going extinct, because you lose biodiversity as a consequence of habitat destruction. This study can help us create an urgently needed strategy that targets the places where biodiversity is bleeding away most rapidly," Dr Roberts said.
The top 10 coral reefs include those found off the Philippines, in the western Caribbean, the Gulf of Guinea, the Red Sea and the Gulf of Aden. Eight of the 10 coral "hotspots" lie adjacent to species-rich land habitats, such as tropical rainforests, which are also under environmental threat.
Tim Werner, senior director of the Centre for Applied Biodiversity Science at Conservation International, said: "The phenomenal overlap of the coral reef hotspots and the terrestrial hotspots shows that we're in the right places for lizards and lizardfish alike."
Dr Roberts said some major coral species had already been lost during the past century when reefs had come under intense pressure from overfishing and pollution from fertiliser and sediment run-off.
He said: "There was a type of fish called the green wrasse which was first described in 1839, but which modern scientists, after looking at museum specimens, can no longer find."
Sylvia Earle, a marine biologist at Conservation International, which funded the study, said: "The study identified 18 areas with the greatest concentrations of species found nowhere else, and determined the hotspots category based on the environmental threats posed to them.
"The oceans have long been considered limitless places where we have little impact on species' survival. But the richest of the shallow tropical marine habitats are at risk of disappearing at an incredibly fast rate. This study is further proof that we need to dramatically increase conservation efforts at sea," Dr Earle added.
More than half of the world's coral reefs are known to be threatened by habitat destruction due to environmental degradation. The study mapped the geographic ranges of a total of 3,235 species, including reef fish, corals, snails and lobsters, four separate animal groups that all require healthy reef environments in order to survive.
Dr Roberts said the creation of marine reserves that were off-limits to fishing was one of the conservation steps that should be taken immediately. About 6 per cent of the world's land was in parks, but at sea less than half of 1 per cent was in any kind of protected area.
"In the seas, conservation is proven to be economically beneficial. Marine reserve protection will pay for itself if designed properly. In marine reserves, fish live longer, grow larger and can replenish surrounding fisheries," Dr Roberts said.
"Five years after setting up a network of marine reserves around the Caribbean island of St Lucia, for instance, fish catches had nearly doubled," he said.
The scientists also identified "wilderness areas" in some tropical reefs where human activity is still severely limited. These are rich in species, such as sharks, that quickly disappear when the coral habitat becomes degraded by over- exploitation.
They include places such as New Guinea, a terrestrial tropical wilderness area that also has coral reefs in near-pristine condition relative to other parts of the world. The study recommends that conservation efforts extend to both the coral reef hotspots and these "wilderness" areas.
Dr Werner said: "The reward for pursuing an integrated conservation strategy for land and sea will be high returns on conservation investments in these regions."Reuse content