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DISPLAYING POSTS TAGGED: seamounts (1)

Mountain life beneath the sea

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by David Staples
Publish date
25 November 2011
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David helps manage MV's Marine Invertebrates collections. He has specialist knowledge of the pycnogonids, or sea spiders.

So, what am I doing here seemingly in the middle of nowhere, 2000km south-east of Capetown and 1500km south of Madagascar?

I have joined an expedition aboard the 95m British Royal Research Ship ‘James Cook’ with a team of scientists exploring seamounts and hydrothermal vents along the South West Indian Ridge (SWIR). Seamounts are mountains under the sea, while hydrothermal vents are fissures in the Earth’s surface from which water heated by volcanic activity issues.

The Royal Research Ship ‘James Cook’ in calm seas. The Royal Research Ship ‘James Cook’ in calm seas.
Image: David Staples
Source: Museum Victoria
 

The SWIR is the tectonic plate boundary that bisects the ocean between Antarctica and Africa and links the Mid-Atlantic ridge and Central Indian Ridge systems. The Central Indian Ridge runs below Australia (as the South Eastern Indian Ridge) and it is speculated that these ridges and the currents they generate may be migration pathways for seamount and vent fauna between the Atlantic, Indian and ultimately the Pacific Oceans.

Map of research cruise route The proposed route for the research cruise exploring the South West Indian Ridge south of South Africa and Madagascar.
Source: IUCN
 

The main focus of this expedition is to investigate the benthic assemblages on these seamounts using a Remotely Operated Vehicle (ROV). The ROV being used is the German ‘Kiel 6000’ which comes with a crew of eight technicians. As its name suggests, this ROV is capable of reaching depths of 6000m.

Remotely Operated Vehicle Remotely Operated Vehicle (ROV) ‘Kiel 6000’, built by Schilling Robotics, Germany and owned and operated by GEOMAR.
Image: David Staples
Source: Museum Victoria
 

On board are oceanographers, geophysicists and biologists all contributing their expertise. We are presently above the Coral Seamount, the top of which comes to within about 300m of the surface; much shallower than the 750m of ocean typical of the seamounts south of Tasmania. While at greater depths some aspects of the fauna are common to both regions, the abundant and diverse fauna found on the upper reaches of this seamount are quite different. It is rare to be able to study fauna at these shallower depths.

In 1999 two moorings, each carrying packets of whale bones and mango wood logs, were experimentally deployed on this seamount and on the Atlantis Bank in expectation that the bones would be colonised by as yet undescribed specialist organisms, such as polychaetes and bivalves. We located the Coral Seamount mooring on our third dive and part of today’s program has been to collect the bones and wood for later analysis. Collections and data from this region are of great interest internationally but closer to home they provide valuable information for the museum’s own scientists for their research projects.

For those interested in keeping abreast of events, Aurélie Spadone (representing the International Union for the Conservation of Nature) is keeping a blog of the expedition.

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