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Deep-sea bounty for sub explorers

Deep-sea bounty for sub explorers

17 November 2004

Undersea Exploration Delivers Treasure Trove

The first ever manned submersible investigation of New Zealand's deep seafloor has produced a wealth of new knowledge about the geology and geochemistry of hot springs discharging from submarine volcanic vents and the unusual ecosystems found around them.

The scientists involved in the project returned to dry land this week after making four eight-hour dives inside the caldera (crater) of an active submarine volcano, 400km northeast of White Island.

Diving to over 1800m in the Japanese-operated Shinkai 6500 submersible, scientists from New Zealand's Geological and Nuclear Sciences Ltd (GNS) collected a range of geological samples and rare seafloor creatures from Brothers volcano for analysis in New Zealand laboratories.

The joint Japanese-New Zealand project chose two main dive sites at the Brothers volcano that turned out to be very different in age, chemistry and marine life. At one site, gas-rich hydrothermal fluids were venting diffusely from the seafloor at 70degC compared to the other site where 300degC fluids were pumping out of chimneys forming dense plumes of black smoke.

Different species had colonised the two sites reflecting the different habitat conditions. Dominant were shrimp, scale worms, crabs, eel-fish, limpets, and tube worms. Of these, the tube worm is probably the most significant find as it is the first time this species has been recorded in New Zealand territorial waters.

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The scientists believe up to 30 percent of the organisms they collected could be new to science.

Also recovered were colonies of heat-loving micro-organisms that may have potential future applications in pharmaceuticals, in bioremediation of contaminated sites, and in biomining.

Seafloor chimneys recovered by the sub's robotic arms were packed with metallic minerals including iron, copper, lead, and zinc.

" We've achieved what we set out to do. We've compiled the first detailed inventory of the geology, vent fluid chemistry, and marine life from a group of active submarine hydrothermal vents along the 2500km-long Tonga-Kermadec Arc," said project leader Cornel de Ronde of GNS.

" We saw scores of chimneys, some six metres tall, each containing thousands of tonnes of metal."

For fellow crew member marine biologist Ashley Rowden, of the National Institute of Water & Atmospheric Research (NIWA), Shinkai 6500 not only enabled efficient sampling of the marine life, but gave the scientists an appreciation of the living arrangements of the organisms that colonise the seafloor vents.

As well as collecting species that were new to New Zealand territorial waters, scientists noticed that other species common at vents elsewhere in the Pacific were absent from Brothers volcano.

" The composition of the seafloor communities and the genetic relationships between populations allows us to better understand the dispersal capabilities and evolution of vent organisms," Dr Rowden said.

Dr de Ronde said as well as a greater understanding of the animal communities that thrive around the vents, the expedition had contributed new knowledge about the formation of seafloor mineral deposits.

"It has also opened the door to further collaboration with the Japanese and we would very much like to see Shinkai 6500 and its mother ship Yokosuka return to New Zealand waters in the future."

Most of the cost of the 17-day expedition was met by Japanese government-owned organisation, Japan Agency for Marine-Earth Science and Technology (Jamstec).


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