Scientists investigating the destruction of coral in the US Virgin Islands were shocked to discover near-perfect reefs at depths never fully explored, writes Anna Fazackerley.

A team of ocean scientists from the Woods Hole Oceanographic Institution in America used an unmanned underwater vehicle to capture pictures of coral reefs up to 70m below the water's surface - beyond the grasp of scuba divers. While shallow-water coral reefs in the Caribbean have been hit hard by disease and pollution in the past few decades, these deep-water reefs had nearly 100 per cent living coral cover.

Hanumant Singh, who led the mission, said: "We went out and saw them in huge, huge abundance. That was really eye-opening."

The Caribbean Fishery Management Council, which assisted with the study, had expected to find further proof of the devastating affect man was having on coral reefs. "This was quite a shock," Dr Singh said. "The programme manager said, 'This is all wrong. We've been telling them back at home that the reefs are really hurting and we need action.'"

51³Ô¹Ï

Dr Singh's vehicle, which operates without wires and can be launched from a small boat, conducted nine dives at night. The team used strobe lighting to take a series of 7,000 digital still images. The two banks - the Marine Conservation District Hind Bank which is south of St Thomas island, and the South Drop near St John - had never been mapped or imaged before. Other divers had glimpsed the reefs, but the diversity and abundance of coral species came as a great surprise. Dr Singh said: "Theories about why these reefs are better protected are hard to confirm."

Dr Singh is keen to go back and explore the areas that his vehicle missed.

51³Ô¹Ï

Annual surveys are planned to assess change to the health of the reef and its inhabitants.