Exploring The Southern Ocean With Seals
Chris - From the University of Saint Andrews, we have Mike Fedak. Thank you for joining us on the Naked Scientist. Now tell us how you're exploring the Antarctic.
Mike - We're taking advantage of some really expert Antarctic explorers namely elephant seals, to help us examine the oceanography that they're dealing with. As they sort of wander around the entire polar ocean, they're excellent candidates for that kind of a job.
Chris - I suppose that one benefit of doing this, Mike, is that if we send a ship, or one of Povl's subs down there then there's always a risk that we may change the environment that we're trying to explore. And therefore we won't get a real picture of what's really there. Whereas if you use a part of nature itself, a seal, an animal, then you might stand a chance of getting a better view.
Mike - Well I'm less concerned about the ships making a sort of disturbance that affects their measurements, they're quite careful about that. I think it's more a case of these animals going places that ships are unlikely to be able to go, and spending time out there, much greater periods of time than a ship would be able to do. It wouldn't be economically feasible to do it. And they can visit bits of the Antarctic that just would not be visited otherwise. We can get data from those places and thereby help the other oceanographic observation techniques to be more successful.
Chris - So technically speaking Mike how are you actually doing this?
Mike - Well we're attaching instruments to the fur of these elephant seals. We glue them on with a fastening epoxy and these instruments basically give us a good idea of where the animal is, they describe the animal's behaviour by looking at the animal's depth, and they also do basic oceanographic measurements, they get solidity and temperature measurements and provide these profiles just in the way you might do from a ship but in places where ships are not likely to go.
Chris - So how deep can a seal go?
Mike - Elephant seals are amazing divers. They can get down to about 2000 metres in the extreme, which is an unthinkable kind of depth. It's a depth so great that you can imagine if you were to open a scuba tank magically at that depth, water would rush in rather than air bubbling out. It's 200 atmospheres of pressure. So amazingly deep divers. And they also dive all the time, they're almost never at the surface. So they're really great ocean explorers.
Chris - And these actual units that you apply with the glue onto the seals fur, how big are they and do they disable the animal in any way?
Mike - No, they don't harm the animal at all, we are able to use animals over several years and running so you can see how well the animals are doing. They're behaving in every way normally and getting just as fat as they ought to get so it doesn't seem to bother them in a way that they can't make up for. And in comparison to an elephant seal they're really not that big. They're about the size of your fist I guess. They weigh about 450 or 400 grams.
Chris - And how do you get the data back from the animals to find out where they've been and what they've been doing?
Mike - Well, the devices have a little computer on board which will allow them to do all the sampling, and then they package that information up into nice little compact radio messages that they send out to a satellite and the satellite then relays it down to us and we can then decode the information and turn it into the data that we need.
Chris - And what have you found so far by doing this? Have there been any things that really jumped out and you thought "Gosh that's surprising, we would never have thought of that".
Mike - Well I think there's a couple of different areas, I mean we started this from the point of view of trying to understand what it is that elephant seals need from the ocean, not really to do the oceanographic exploration for the sake of oceanographers but really to learn for the sake of the animals which bits of the ocean were important to them. We've identified the kind of places that they require. We now know that they're quite diverse in the sense that there's three basic strategies they use. Some are real deep ice explorers, that go way down to the Antarctic continent and sort of visit the benthos down on the continental shelf around the Antarctic margin, well into the ice. And another group effectively are animals that explore the frontal zones that are slightly lower latitudes, up around 45 degrees, to 50 degrees North or so. Areas anywhere from the Polar front down the Southern Antarctic front, and explore a much more sort of pelagic part of the ocean.