Christmas Island crabs make waves

Singapore scientists discover new species in trip to 'crab capital'
Victoria Vaughan, Straits Times 6 Feb 10;

CHRISTMAS has come early for a group of Singapore scientists who have discovered new crustaceans during an expedition to the 'crab capital of the world'.

Three new species have been discovered at Christmas Island in the last two weeks during a research trip planned by the Raffles Museum of Biodiversity Research of the National University of Singapore, with eight researchers from Singapore, Japan and Australia.

Christmas Island, which lies in the Indian Ocean, south of Sumatra, was chosen because of its long history with Singapore, said the scientists.

It used to be owned by Singapore but was sold to the Australian government in the late 1950s, and staff of Singapore's original Raffles Museum did the first comprehensive study of the island's fauna in the 1940s.

The leader of the two-week expedition, crab expert Peter Ng, said that the group had made several important discoveries, including two new species of cave crabs - which are brown and measure about 1.5cm - the first such crabs to be found on Christmas Island, Australia and the Indian Ocean.

Professor Ng, who heads the Raffles Museum and is from the NUS Department of Biological Sciences, first discovered cave crabs about 20 years ago. Since then, eight species have been found.

'I was instantly able to recognise them at Christmas Island because I know the eight species so well and I had not seen these two before.'

The third discovery in the limestone caves of the island was a half-blind shrimp which, at 8 to 10cm, challenges the view that only small creatures dwell there.

For Prof Ng, the island is a treasure trove as it is swarming with crabs.

Even cars must make way for the giant robber crabs - which grow up to 50cm across - when they traverse the road.

'There really is no place like it in the world - crabs dominate the landscape as there is no natural predator.

'When the red crabs swarm to the sea to breed, they turn the cliff red,' he said.

The team laid traps in the water, which were baited with cat food or fish flakes, in their efforts to net new species.

Their findings were then photographed and some are kept for further study.

The information will help the local staff better manage the island's crab population.

'If they know that those caves have so many new species, they have to mitigate how people use them.

'For example, we can't have people washing their hair or putting detergent in the water,' explained Prof Ng, who hopes the research will enable Australia to get the island designated as a Unesco World Heritage site.

This will help in enforcing stricter import controls to try and avoid the introduction of alien species that would threaten the crabs.

This happened 10 years ago when yellow ants - thought to have been brought in by cargo ships, wiped out the crabs in certain areas.

The island's national parks team stepped up to help guide the researchers.

Said chief ranger Max Orchard, 58: 'We knew we had a natural wealth of ecology. It was just a matter of getting the experts here to unearth it.

'Their work will certainly influence our management, and having new species discovered reinforces the need to place Christmas Island on the World Heritage list.'

Pointing out that the island was better known for mining and boat people, he added:

'It's a bit of a shame... we feel the future of the island lies in its unique biodiversity.'