22 December 2005

Ocean census reveals weird and wonderful

The world beneath our oceans is a mystery only just starting to be revealed but if the carnivorous sponge is any indication, it must be pretty weird down there.

About 1700 researchers in 73 countries are now halfway through the Census of Marine Life, a mammoth 10-year project to catalogue the life-forms of our oceans - from the tiniest microbes to the biggest whales.

In the past year alone researchers have added 78 new species of fish to their records.

On expeditions to the depths of the South Atlantic and Southern oceans at least half the jellyfish, sponges and other specimens found had never been seen before.

The 5mm-wide carnivorous sponge which engulfs other organisms with its mouth was one of those surprise finds - sponges are normally filter feeders.

Census scientific steering committee vice-chairman Dr Victor A. Gallardo said the sheer scale of the ocean was the biggest challenge.

"The deep sea floor is an area of 300 million sq km, of which the area sampled to date is equal to a few football fields," he said.

"The number of sea-mounts - underwater mountains rising at least 1000m from the ocean floor - is estimated at between 30,000 and 100,000, of which a few hundred have been sampled, less than 50 were sampled well."

Apart from adding to our knowledge of the oceans, the census will allow better management of commercial fishing. US scientists electronically tagged 2700 salmon to track their migrations across the Pacific Ocean from 16 river systems.

Lead scientist David Welch said abundant and sustainable stocks of commercial fish were closer to being a reality. "The new data reveals for the first time those zones of the ocean where we have the highest leverage for conservation and thus smarter fishing."

Australia is one of four remaining areas in the world which still has strong and diverse stocks of tuna - an important predator, the numbers of which have been dramatically decreased by commercial long-line fishing.

Since the introduction 50 years ago of long-line fishing boats - which hook fish on lines up to 100km long - fish stocks have been affected. But researchers found there is still high diversity of species on the east coasts of Australia, the US and Sri Lanka, and also south of Hawaii and in the South-Eastern Pacific Ocean.

Tasmanian CSIRO researcher Bronwyn Innes contributed to a library of DNA "barcodes" which identify species and allow easy determination of what fish have been taken.

Source: www.thecouriermail.news.com.au


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