BIODIVERSITY: Frigid Polar Regions Teeming With Life

• by Stephen Leahy (chicago, u.s.)
• Friday, February 20, 2009
• Inter Press Service

Remarkably, at least 235 of these species live in both the North and South poles and nowhere else - despite the 11,000-kilometre gap.

'One hundred years ago, Antarctic explorers like Scott and Rutherford saw mostly ice,' said Victoria Wadley of the Australian Antarctic Division. 'In 2009, we see life everywhere.'

Wadley is one of over 500 scientists from 25 countries participating in the 'Census of Antarctic Marine Life' survey which saw 18 major research voyages during the International Polar Year (2007-2008) that just concluded.

Scientists have thus far identified 7,500 animals in the Antarctic and 5,500 in the Arctic oceans. Total global marine life is estimated at 230,000-250,000 species. To obtain this new data, researchers took samples from nearly one million locations. Those places include seafloors exposed to light for the first time in as much as 100,000 years when ancient ice shelf lids melted and disintegrated in recent years.

While the analysis of all samples is not yet complete, it is expected that the Antarctic will win the total species count, suggests Bodil Bluhm, a researcher at the University of Alaska. While both are bitterly cold regions of ice and snow, they are also very different.

'The Antarctic is a continent with an ocean around it, while the Arctic is an ocean surrounded by land like the Mediterranean Sea,' Bluhm said in an interview.

Of the two, the Antarctic is far larger and open to the rest of the oceans, perhaps explaining the higher level of biodiversity, she suggests.

The big surprise for researchers were the 235 species, including five whale species, six sea birds and nearly 100 species of crustaceans, that are found exclusively in polar regions. Bluhm studies one of these, a tiny species of 'sea butterfly' - a free-swimming snail or pteropod about the size of a lentil. 'How did they get to both poles?' she wonders.

And for just how long these species have been separated and whether these 235 species have drifted apart genetically is unknown. 'This opens up a lot of interesting evolution type of questions,' she says.

This first comprehensive survey of the life in the polar seas comes 200 years after commercial fishing and whaling have had a huge impact, especially in the Antarctic, says Julian Gutt of the Alfred Wegener Institute for Polar and Marine Research in Germany.

'The region was once full of whales, seals and penguins,' Gutt told IPS. And while the seals and penguins have recovered in recent decades, the whales, especially the large ones like Blue and Sperm whales, have not. 'That's a significant change but we don't know what that means for the ecology of the region,' he says.

Fewer whales may mean more krill, a shrimp-like creature that is main prey of most whales. And more krill in the last few decades may have helped the recovery of seals and penguin populations, he speculates.

However, commercial krill fishing is having a big impact and many stocks are being overfished. 'Strict management is needed to prevent impacts on penguins and seals,' Gutt says.

And there is new evidence that shows climate change is warming the southwest Atlantic, leading to 40 percent declines of krill populations. 'There is no direct evidence yet of penguins or seals going hungry as a result,' he says.

But what is affecting penguins is the declining sea ice cover in the rapidly warming West Antarctic peninsula, he adds. The loss of ice cover is reducing the abundance of krill and the fish species that eat them - both food sources for the resident Emperor and Adelie penguin colonies.

In the Arctic, the impacts of climate change are more pronounced in part because half of the Arctic Ocean is less than 50 metres deep. The loss of permanent sea ice means more of the ocean is exposed to the sun and that has produced large blooms of algae. And the region has become more favourable for other species, says Bluhm.

'Crab species once found only 500 km to the south in the north Pacific are beginning to move in,' she says.

These and other polar sea discoveries were only possible because of the resources and international cooperation of the Census of Antarctic Marine Life.

'In these unique oceans, where the water temperature is colder at the surface than below, we are establishing the first benchmarks of marine biodiversity against which change may be measured,' concluded Census Chief Scientist Ian Poiner in a statement.

© Inter Press Service (2009) — All Rights ReservedOriginal source: Inter Press Service

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