Antarctic life – penguins and seals – podcast
Learn about research into the stress levels of Weddell seals that summer near Scott Base, the fishing habits of the seals, Adélie penguins and emperor penguins and where they cohabitate in Cape Crozier. The researchers are keen to piece together the Antarctic food web puzzle to better understand the interconnections and to enable smart conservation decisions.
In this fourth episode from the Voice of the Sea Ice podcast series, RNZ science communicator Dr Claire Concannon talks to scientists researching animals in Antarctica. This includes Weddell seal researcher and PhD candidate Arek Aspinwall and seal and penguin expert Associate Professor Michelle LaRue. Both are from the University of Canterbury.
The long-form version of this podcast is on the RNZ website here. The extended version includes an interview with Professor Steve Wing. Steve is researching how crocodile ice fish are linked to some of the other parts of the food web.
Transcript
Arek Aspinwall
Weddell seals are really cool in that they can find all these cracks and holes and breathe and go under the sea ice, whereas the things that eat Weddell seals like leopard seals and killer whales, they can’t get this far into the Sound at this time of year. So these pups are pretty safe – there’s not really anything that can attack them at this point in the year.
This mother-pup pair, which is about 20 metres from us, this is the newest-born pup. It’s yet to be tagged. I’ve been able to pretty consistently collect scat and urine samples from them, so I’m hoping to get another today. We’ll see how it goes.
Dr Claire Concannon
Quite big for a new pup.
Arek Aspinwall
They grow fast. They put on like 3 or 4 kilos a day. When they’re born, they’re about 30 kilos, and within 6 weeks, they weigh 100 kilos.
Dr Claire Concannon
The plan is that this baby seal, 5 days old now, will get tagged today. All the Weddell seals in Southern McMurdo Sound are tagged – part of an ongoing study led by the US Antarctic Program. They also survey and re-site seals each season, so they have records on individual seals going back for years.
Arek Aspinwall
This seal here, if I remember correctly, is either 8 or 9. And she’s a first-time mother, so this is her first pup, which is cool. And we know that because we’ve re-sited her 8 years in a row since she was pupped and have seen that she’s never had a pup so far.
So we’ve got that data, which is cool. And that’s just come from years of hard work from lots of people.
Dr Claire Concannon
Arek has a permit to get closer, but I do not. So I hang back to watch him work. He photographs the seals, including getting a shot of mum’s tag, and then scoops up some of their scat and urine into a sample jar.
And yes, the question is why. Why is Arek collecting seal poop?
Arek Aspinwall
Quite often, research stations end up in the bits of land that are very useful for animals, because the same reason that Scott Base is here is sort of why seals are here as well. So we interact with animals a lot. We coexist in the same spaces, and we always have an impact, and I’m trying to figure out what that impact is – from the rebuild, from Scott Base as is as well. Because we can hear construction, there’s also rumbling that goes through the ground and will go through the ice that could impact the seals. We accept that we always have an impact, and it’s about weighing up the pros and the cons.
And this is why we have ethics committees and processes to go through, to be like, you know what, if we want to have an Antarctic presence, we will disturb the environment to a certain degree, and we need to figure out what’s an acceptable amount and what’s an acceptable impact.
Dr Claire Concannon
While the latest Scott Base rebuild plans are under development following a reset in 2024, that upgrade of the wind farm is currently under way. So there have been earthworks to prepare the site and modifications of the access road, and Arek is analysing the poop to see if this activity is stressing the seals.
Arek Aspinwall
I am essentially looking at the stress hormone cortisol, which is a hormone that basically all mammals produce. When animals are stressed, they secrete more of it. And you can tell how much of it has been secreted in the scat and the urine.
And back in Christchurch, I basically analyse the concentration of that and I can figure out whether or not there is more being produced here than control sites kind of up the island. And also I’m hoping to be able to pair some short-term responses. So on days where there’s a lot of construction, there’s a lot of explosives, is the urine produced on that day, is it going to have higher cortisol than on days where there’s quieter, like a Sunday where there’s no work going on? Is there a difference between the samples collected on that day or a different day?
Dr Claire Concannon
So this land-fast sea ice is important habitat for the seals here, especially the mums.
We can hear the quiet noises of them above water. Pups calling to mums, the big deep breaths they take when they pop up in a hole and the little gnawing sound of them using their teeth to keep the holes in the ice open. But occasionally, you can also hear the sound of their underwater calls through the ice.
And it’s even more magical to listen to when you put a hydrophone down.
Of course, this Weddell seal haven doesn’t last. The sea ice changes throughout the year, and as it does, they shift around to try stay ahead of the ocean-dwelling big sharp teeth that would love some seal snacks.
Arek Aspinwall
After Christmas, the sea ice starts breaking out further up in the Sound, and all the seals in the region essentially get funnelled down to where Scott Base is, and they’re here to moult. They lose last year’s fur, and they get a new fur coat for the new year. It’s called a catastrophic moult, because it’s just so energetically expensive and complex, and they all show up in January, February. You start getting huge numbers that show up. They tend to hang out a bit further inland, where the multi-year sea ice is kind of almost up at the ice shelf.
So come March, the ice starts forming again, and they don’t want to get trapped here with thick sea ice with no access to the water below to eat food, so as the ice starts to reform and grow, they scatter again. So they sort of follow the sea ice. As the sea ice grows and becomes really big around the continent, they spread out. And then as the sea ice recedes, they funnel down into McMurdo Sound.
Dr Claire Concannon
Arek’s control site is at the eastern end of Ross Island, where a population of Weddell seals hangs out far from any research bases. But they’re not alone.
Associate Professor Michelle LaRue
We’re heading out to Cape Crozier to put satellite tags on emperor penguins, Adélie penguins and Weddell seals to test niche partitioning theory.
Dr Claire Concannon
This is Dr Michelle LaRue, Associate Professor at the University of Canterbury, and I caught up with her just before she left Scott Base.
Associate Professor Michelle LaRue
There’s not very many places in Antarctica where all three coexist in that small of a space.
Dr Claire Concannon
And the question Michelle is asking is, have they divided the space and snacks neatly between them? Or are they competing for the same fish?
Associate Professor Michelle LaRue
What we suspect – or at least what I suspect – is that we’ll see this kind of allocation where, you know, the seals and the penguins will dive differently, they will go to different locations, and they don’t necessarily have to directly compete with each other. And yeah, in other words, there’s probably enough space and enough fish in the ocean for all of them to coexist.
Dr Claire Concannon
To investigate this, they use satellite tags that they fit to 10 each of the emperor and Adélie penguins and 10 Weddell seals. These tags stay on for a few months and then fall off when the seals and penguins moult.
Associate Professor Michelle LaRue
So yeah, we’ll be able to see literally, like in real time, where they’re swimming, how deep they’re diving.
Dr Claire Concannon
And since they’ve got into the data, their initial analysis does point towards the niche partitioning theory being correct.
It seems that these three species are fishing in quite different places. Though it is early days, says Michelle, they’ll be back over the next few seasons to do the same thing so they can gather enough data to be sure.
But back to Cape Crozier, to which Apsley Cherry-Garrard, along with Wilson and Bowers, all members of Scott’s ill-fated Terra Nova Expedition, headed to in July 1911 to collect emperor penguin eggs for science.
And yes, July. The depths of winter in total darkness. That trip is what Cherry-Garrard’s book The Worst Journey in the World is named after.
Apsley Cherry-Garrard
The horror of the 19 days it took us to travel from Cape Evans to Cape Crozier would have to be re-experienced to be appreciated. And anyone would be a fool who went again.
Dr Claire Concannon
These days, it’s a short helicopter ride from Scott Base to Cape Crozier. And in Michelle’s telling, it’s actually quite lovely there.
Associate Professor Michelle LaRue
Very pristine, beautiful spot with hundreds of thousands of Adélie penguins. Probably about 1,200 to perhaps 2,000 emperor penguins and a handful of Weddell seals. We actually don’t know how many exactly there are, but probably no more than 50 or so.
Dr Claire Concannon
The Adélie penguin rookeries fill the hillside, a mass of black and white bodies on the black-brown earth. They’re medium-sized penguins, about 70 cm in height. They’ve got a black balaclava look, with a white ring around their eyes, like reverse eyeliner.
Where island ends is also where the edge of the Ross Ice Shelf interacts with the ocean. And so the sea ice is frozen in between these cliff-like, jagged edges of the ice shelf, forming the perfect place for the emperor penguin nursery.
Associate Professor Michelle LaRue
They require that habitat for raising their young, for breeding. It’s a really unique habitat.
Dr Claire Concannon
Emperor penguins are the big boys. The heaviest and tallest, getting up to 1 metre in height. You know them with their iconic black heads and sunset yellow ear patches that blend under their chins and into their white bellies.
Scientists don’t often admit to favourites, but sometimes, if the evidence is there ...
Associate Professor Michelle LaRue
Emperor penguins are, I think, some of the most badass animals in the world, because they go through the most extreme situations that I can possibly think of. I mean, very famously, obviously, Antarctica is the highest, driest, windiest, coldest continent on the Earth. And these are birds that come back to the continent to breed in the middle of wintertime when it’s like the worst of all of those things.
Dr Claire Concannon
They return in March or April to start courting and mating. Peak breeding is some time in May, and peak huddle is June, where huddle means precious egg-minding.
Associate Professor Michelle LaRue
So the other thing that I love about emperor penguins is they’re the only penguin that does not technically have a nest. It is the father’s feet. So when the female lays the egg, it comes out and it’s on her feet. And then they do a kind of like a little dance and they transfer the egg from the female to the male. And then he covers it with his brood pouch and it stays nice and incubated in there.
And then the female heads for the hills and goes swimming for a couple of months. And then the males just hunker down and stay as warm as they can until the females return.
Dr Claire Concannon
Females return end of July or mid-August when the egg hatches. Then it’s chick-feeding time with the parents alternating between chick minding and food finding.
Around September, the rapidly developing, down-covered chicks need so much grub that both parents are on the job.
In early December, the chicks begin to shed the fluff and grow sleek, waterproof feathers that they’ll need to fend for themselves. At this stage, they’re left to their own devices, and when they’ve got the full complement of shiny new feathers, they leave the nursery some time in December or January.
Along with the seal scat they collect for Arek, Michelle and her team will also take some blood, seal whisker and penguin feather samples to investigate the health of the animals and to look at what’s going on in the food web here.
But the other big question is, with so much life relying on Antarctic sea ice, what does its future look like?
Dr Natalie Robinson
In the last 10 years, the Antarctic had been very stable, and then suddenly there was a bit of a drop in the sea ice extent. It wasn’t very much, but then in the last 2 years, it’s been much more dramatic, so it’s like nothing that we’d ever seen.
Dr Claire Concannon
That’s next time on Voice of the Sea Ice.
Thanks to Arek Aspinwall and Dr Michelle LaRue from the University of Canterbury. Thanks also to Dr Steve Wing of the University of Otago.
Reporting for this series was supported by Antarctica New Zealand, Ellen Rykers and Liz Garton helped with production, sound mixing was by William Saunders and editing help on this episode was by Justin Gregory.
Thank you so much for listening. If you’re enjoying the series, please do share it with a friend. I’m Claire Concannon. Have a great week. Kia pai, te wiki.
Acknowledgements
This podcast is courtesy of RNZ. It is from the Voice of the Sea Ice series by Dr Claire Concannon. The series was made with travel support from the Antarctica New Zealand Community Engagement Programme.
Arek Aspinwall, University of Canterbury
Associate Professor Michelle LaRue, University of Canterbury
Professor Steve Wing, University of Otago
