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Mapping seamounts

In this video clip NIWA scientists Malcolm Clark, Arne Pallentin and David Bowden explain what seamounts are and how they are gathering information about the terrain and the organisms that inhabit them. Malcolm tells about the significance of seamounts while Arne shows a three dimensional map that has been produced of Scott Island using the multibeam. David tells how they use the Deep Tow Imaging System (DTIS) to capture footage along the sides of the seamounts.

Points of interest for teachers:

  • Students might want to try the multibeam activity to better understand how underwater maps are produced.
  • What organisms does the camera show while it is floating on top of the seamount?

Transcript

MALCOLM CLARK

We’re seeing essentially underwater volcanoes, underwater mountains they rise from the abyssal depths of four to five thousand metres – right up to near the surface, in some cases they break the surface and are visible as emergent islands such as Scott Island which we have just come from on the Scott’s seamount chain near the Antarctic.

ARNE PALLENTIN

The seamounts are remnants of geological processes and they’re essentially like a mountain in a landscape. You see here the flat sea floor and then you have a mountain rising from the sea floor above the sea floor, in a lot of cases many thousand metres, in this case there is actually a rise from about 2, 500 metres to 600 metres in a distance of just a few kilometres five or seven kilometres I think.

DAVID BOWDEN

Seamounts are a bit of a challenge for us with the cameras. A seamount is like a, like a mountain on land, a terrestrial mountain, it’s a steep rugged environment with a lot of rocky out crops and what we’re trying to do is we’re trying to dangle a camera on hundreds, if not thousands, of metres of wire and we’re trying to fly it precisely down the slope of the mountain. And as you can see we’re got a lot of boulder, a lot of rubble, scree slopes with jagged, rocky out crops. Trying to control the camera at two to three metres above the seabed so we get the right image quality – is a real challenge. The winch drive is excellent at it, but even then you can see occasionally there – working hard to keep it just above the seabed. For seamounts the camera is an enormously valuable tool it’s giving us the – a real image of how the – how the organisms are feeding, how they’re interacting with each other and which parts of the environment they’re occupying, so we’re seeing very distinct patches of organisms, here we’ve got very dense accumulations of – dense populations I should say of suspension feeding off ophiuroids which then give way to crinoids at other points and it’s only through the camera that we’re actually managing to get this - the structure of the benthic habitat

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