”Brittlestar City’ on underwater summit thrive on Antarctic Circumpolar Current.

An expedition in April to survey the Macquarie Ridge aboard the Research Vessel Tangaroa of New Zealand’s National Institute of Water & Atmospheric Research, host of the Census of Marine Life seamount programme, CenSeam made some interesting discoveries into seamount geology and physics.

Scientists, exploring the underwater mountain range south of New Zealand, discovered and documented the “Brittlestar City” found at the peak of a seamount – an underwater summit taller than the world’s tallest building, rising 750-meters above the ocean floor.

Tens of millions of brittlestars are able to take advantage of the seamount’s shape and to the swirling circumpolar current flowing over and around it at roughly four kilometers per hour. It allows them to capture passing food simply by raising their arms, and it sweeps away fish and other hovering would-be predators.

PHOTO: Close up of diverse assemblage of invertebrates on rocky substrate on shallow top of seamount. Includes brittlestars, anemones, sponges, soft corals, worms.
Brittlestars on Macquarie Ridge.

Photo courtesy of NIWA, © 2008.

NIWA reports that Macquarie Ridge is one of a few places where the Antarctic Circumpolar Current is detoured in its endless clockwise churn at the globe’s southernmost latitudes – playing a vital part in the global ecosystem, merging and mixing waters of the Atlantic, Indian and Pacific Ocean.

MAP: Showing location of Macquarie Ridge. Courtesy of NIWA © 2008.

Map of Macquarie Ridge.

Full identification of the specimens gathered by the expedition may take many years. The eight biologists on board believe some species collected have never before been recorded in the region while some may be new to science.

Physicists aboard the Tangaroa calculated the speed of the Antarctic Circumpolar Current over the top of the seamount at a “rattling” 2 knots (about 4 km per hour).

“This current is estimated to be 110 to 150 times larger than all the water flowing in all the rivers of the world,” says Dr. Mike Williams of NIWA. “In terms of the world’s oceans, New Zealand sits right beside the motorway.”

“Understanding this current will shed light on how much water flows into the Pacific as opposed to continuing to circumnavigate Antarctica. This is important for understanding, and ultimately predicting, the impact of potential changes in the current on climate throughout the Southwest Pacific.”

Scientists also took this ocean area’s temperature and salinity readings for the first time since the 1960s, looking for climate-related changes, and obtained water samples to measure and compare levels of marine life nutrients.

“Seamount ecosystems are extremely valuable to the global environment. They are also the target of offshore commercial fishing, and are of potential interest for seabed mining,” says Dr. Rowden of NIWA. “The long term impacts of such commercial activities need to be quantified.”

To read further visit the New Zealand’s National Institute of Water & Atmospheric Research website here.

PHOTO OF THE DAY:

Amazing creatures of Antarctica. A cable portrudes from the ice wall at Explorer’s Cover, New Harbor, McMurdo Sound. The cable is used for the Remotely Operable Micro-Environmental Observatory (ROMEO), an underwater camera. Connected to onshore equipment and linked by radio to the Internet, ROMEO allows scientists to study benthic fauna year-round.

Underwater life in Antarctic Sea.

Photograph by: Steve Clabuesch, National Science Foundation. Date Taken: November 12, 2005

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~ by abstraktbiblos on Tuesday, 20 May, 2008.

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