"Brittlestar City" gives clues to seamount life
By Alister Doyle, Environment Correspondent
OSLO, May 18 (Reuters) - Millions of starfish-like creatures have been found in a novel colony on a subsea mountaintop south of New Zealand, aiding knowledge of mysterious seamounts that dot the oceans, scientists said on Sunday.
Fewer than 200 seamounts -- mountains that rise from the ocean floor without piercing the surface -- have been surveyed out of an estimated 100,000 around the world. They are often rich in marine life in seas under threat from over-fishing.
Tens of millions of tiny brittlestars were found on a peak 90 metres below the sea surface on the subsea Macquarie Range stretching 1,400 km (870 miles) south of New Zealand towards Antarctica, scientists from New Zealand and Australia said.
They dubbed the peak, filmed with a robot submarine in April, "Brittlestar City" after the five-armed creatures that are a type of echinoderm related to starfish, sea cucumbers, sea lilies, and sea urchins.
"As far as we know, such aggregations (of brittlestars) have not been observed before on the top of a seamount," said Ashley Rowden of New Zealand's National Institute of Water & Atmospheric Research.
Usually, corals and sponges are found on the peaks of seamounts, he told Reuters. In some places hundreds of the tiny brittlestars were crammed in per square metre on the flat top of the mountain, covering about 100 sq kms (38.61 sq mile).
The seamount rises 750 metres from the surrounding sea floor and is swept by a current about 4 km (2.5 miles) per hour that may help keep some predators away from the brittlestars, more often found on the flanks of seamounts.
"It's this sort of information will allow us to improve our knowledge of biodiversity in the deep sea, and how best to manage it," Rowden said. Corals, cod and other fish were also observed around the seamount.
ARM WAVING
Brittlestars feed on plankton by simply waving their arms into the current. Food gets trapped on sticky mucus on their spiny arms.
Knowledge of the state of life on seamounts in the Macquarie Range may also help monitor future changes, for instance if ocean currents around Antarctica are affected by global warming.
Representatives of up to 200 governments meet in Bonn, Germany, from May 19-30 to review efforts to protect the diversity of life on earth from threats such as rising human populations, destruction of habitats and climate change.
The two species observed were tentatively identified as known types of brown-black and orange-red brittlestars.
The scientists, also part of a global Census of Marine Life, sampled eight seamounts on a month-long voyage in April. "Some species collected have never before been recorded in the region while some may be new to science," according to the biologists aboard the research vessel Tangaroa.
"Undersea mountains can be highly productive and biodiverse, sometimes host unique species and serve as feeding grounds for fishes, marine mammals and seabirds. They also may serve as important way stations for marine migrations," a statement said.
They could also be targeted by commercial fishing or mining companies.
-- For Reuters latest environment blogs click on: blogs.reuters.com/environment/ (Editing by Myra MacDonald)
OSLO, May 18 (Reuters) - Millions of starfish-like creatures have been found in a novel colony on a subsea mountaintop south of New Zealand, aiding knowledge of mysterious seamounts that dot the oceans, scientists said on Sunday.
Fewer than 200 seamounts -- mountains that rise from the ocean floor without piercing the surface -- have been surveyed out of an estimated 100,000 around the world. They are often rich in marine life in seas under threat from over-fishing.
Tens of millions of tiny brittlestars were found on a peak 90 metres below the sea surface on the subsea Macquarie Range stretching 1,400 km (870 miles) south of New Zealand towards Antarctica, scientists from New Zealand and Australia said.
They dubbed the peak, filmed with a robot submarine in April, "Brittlestar City" after the five-armed creatures that are a type of echinoderm related to starfish, sea cucumbers, sea lilies, and sea urchins.
"As far as we know, such aggregations (of brittlestars) have not been observed before on the top of a seamount," said Ashley Rowden of New Zealand's National Institute of Water & Atmospheric Research.
Usually, corals and sponges are found on the peaks of seamounts, he told Reuters. In some places hundreds of the tiny brittlestars were crammed in per square metre on the flat top of the mountain, covering about 100 sq kms (38.61 sq mile).
The seamount rises 750 metres from the surrounding sea floor and is swept by a current about 4 km (2.5 miles) per hour that may help keep some predators away from the brittlestars, more often found on the flanks of seamounts.
"It's this sort of information will allow us to improve our knowledge of biodiversity in the deep sea, and how best to manage it," Rowden said. Corals, cod and other fish were also observed around the seamount.
ARM WAVING
Brittlestars feed on plankton by simply waving their arms into the current. Food gets trapped on sticky mucus on their spiny arms.
Knowledge of the state of life on seamounts in the Macquarie Range may also help monitor future changes, for instance if ocean currents around Antarctica are affected by global warming.
Representatives of up to 200 governments meet in Bonn, Germany, from May 19-30 to review efforts to protect the diversity of life on earth from threats such as rising human populations, destruction of habitats and climate change.
The two species observed were tentatively identified as known types of brown-black and orange-red brittlestars.
The scientists, also part of a global Census of Marine Life, sampled eight seamounts on a month-long voyage in April. "Some species collected have never before been recorded in the region while some may be new to science," according to the biologists aboard the research vessel Tangaroa.
"Undersea mountains can be highly productive and biodiverse, sometimes host unique species and serve as feeding grounds for fishes, marine mammals and seabirds. They also may serve as important way stations for marine migrations," a statement said.
They could also be targeted by commercial fishing or mining companies.
-- For Reuters latest environment blogs click on: blogs.reuters.com/environment/ (Editing by Myra MacDonald)
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