Paradise found (part two): meet the new species of the Saba Bank Atoll

One week after 'The Independent' reported the discovery of a host of new species in New Guinea, Steve Connor reveals the astonishing findings of an expedition in the Caribbean

An underwater paradise filled with exotic fish, marine plants and coral reefs has been discovered by professional scuba divers exploring the shallow waters of a sea mountain in the Caribbean.

More than 200 species of fish - many of them new to science - have been documented during a two-week exploration of the Saba Bank Atoll, a coral-crowned seamount 160 miles south-east of Puerto Rico in the Dutch Windward Islands.

The diversity of the marine life has astonished the scientists who found dozens of new marine animals, including two types of goby fish, and vast seaweed beds littered with plants that have yet to be named. "We discovered a new species every day we were there," said Michael Smith, director of the Caribbean Biodiversity Initiative of Conservation International, a not-for-profit research organisation. "It's a big surprise. That rate of discovery is unusual for the Caribbean, at least in shallow water, and I've been doing this sort of research for 20 years."

Before the expedition, only 35 species of fish had been documented in the region, but that has now increased six-fold. The scientists have itemised 12 new species of seaweed, but believe this is a conservative estimate and that the final number of new plants may be nearer 20.

Saba Bank is a classic coral atoll consisting of a submerged mountain which is crowned at the summit with a ring of actively growing coral reefs. It is the largest atoll in the Atlantic Ocean basin and the third largest atoll on Earth. It probably began to form about half a million years ago following a volcanic eruption. The flat-topped seamount rises 5,900ft above the seafloor but does not actually break the sea surface. Because there is no island directly associated with the bank, it has never suffered from the direct effects of human habitation. The shallow waters of the Saba bank extend across a total surface area of 850 square miles and include vast fields of corals which have survived in largely pristine condition. Unpredictable currents and winds have protected the seafloor, although in recent years it has come under threat from passing oil supertankers that use the bank as a cheap anchorage.

Ten years ago, a report by the Dutch government warned that the Saba Bank's unique environment could be degraded by commercial fishing and passing marine traffic. "A number of human activities was distinguished as having (potentially) severe effects on the Saba Bank and its resources. Most prominent were overfishing and anchoring," the report said.

"Other possibly serious threats to the bank's natural resources include the use of dispersants after oil spills, ship grounding and collisions," it added.

Conservation International said although Saba Bank had escaped many of the typical threats posed by inhabited islands, passing supertankers still threatened the pristine nature of the underwater paradise. "A petroleum trans-shipment depot on neighbouring St Eustatius Island causes significant marine traffic, including oil supertankers in the area around the submerged atoll," a spokesman said. "The fragile ecosystems of Saba Bank are damaged by anchors and chains of ships that avoid anchoring fees in territorial waters of St Eustatius."

Dr Smith said the latest expedition would give the local inhabitants of nearby Saba Island the ammunition to argue for international protection of the Saba Bank. "It has the potential to be one of the really important, healthy places in the Caribbean, where the coral can help to colonise other places in the region that have suffered degradation," he said.