Only about a quarter of the earth's sea floor has been mapped using mostly sonar systems on ships. But for the past 20 years along the east Antarctic shelf seals with satellite tracking have been helping scientists map the seafloor.
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00:00 As you say, this program or this project has been going for 20 years.
00:05 So it started way back in 2004 with our French colleagues and now a collaboration with the
00:13 Institute, the Integrated Marine Observing System down in Hobart and of course, Sydney
00:20 Institute of Marine Science and a whole lot of others.
00:23 And the great thing about this, of course, is that we're attaching these really clever
00:27 instruments made by our colleagues in Scotland that measure temperature, salinity, depth
00:33 and also fluorescence, some of the newer instruments.
00:36 And this gives us a really integrated view of what's going on in the ocean from the physics
00:41 through to productivity and then the animal behavior, which we're really interested in
00:45 to see how animals are responding to the in situ, so the direct changes in their environment.
00:51 And then we can track that and see how well and identify the spots in the ocean that are
00:56 good for animals and how they then put on conditions.
01:01 So to do that, we actually look at the dives of each individual seal and we can calculate
01:07 the angles at which they are diving so that if the angles when they dive are really shallow,
01:14 the seals are in really good condition because blubber is more buoyant than muscle and then
01:21 vice versa is true too.
01:22 So we can actually look at the dive angles and then identify the physics and the productivity
01:29 and relate that to the seals condition.
01:31 And so it's their deep diving skills that obviously they're helping you to map the seafloor,
01:36 but also correct misunderstandings about depth as well.
01:40 Yeah, that's exactly right.
01:42 So elephant seals in particular, which most of the images in the background there were
01:46 of are really deep diving animals.
01:49 So there are dives over 2000 meters, which is just an astonishing number, of course.
01:56 And that means that they will go to the bottom of the ocean floor.
02:00 And as you mentioned in your little introduction, only about a quarter of the world's seafloor
02:07 has been mapped with ships and high resolution equipment, which means there's a huge amount
02:14 of the ocean that hasn't been mapped.
02:16 And because the seals are diving often below where we think the bottom is, we can use the
02:21 seal dive depths to recalibrate the depths of the ocean.
02:26 And then this helps us really understand where there are channels on the seafloor that the
02:32 modified circumpolar deepwater, which is this water that's returning to Antarctica after
02:38 it's been circulating around in the ocean, gets onto the shelf and then how that may
02:43 intrude into the cavities below the ice shelf and promote melting, for example.
02:49 And this gives us a much better picture when we can map that accurately on melt rates and
02:55 how that may be affecting the input of fresh water into the ocean.
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