What do animals eat in Antarctica?
'If Antarctica is so barren, what do the animals that live there eat?'
Sally Le Page got into contact with Huw Griffiths from the British Antarctic Survey to ask him about the ecosystem of the supposed barren Antarctic area...
Huw - That's a really good question because Antarctica actually isn't as barren as it appears on the surface. Beneath that ice that you see, especially in the oceans, it's an incredibly rich and diverse place, but on land, the biggest plants are mosses and lichens and things and the biggest animals are wingless midges. So the food chain on land is very short and largely microbial. But essentially once you get into the oceans, you've got the biggest animals on Earth, the blue whales and everything feeding on what is quite a short food chain for the mammals and birds. You've got tiny microscopic phytoplankton, which is feeding these tiny animals that people have heard of that are called krill, which are a bit like shrimp, but they're actually a bit bigger than people think. They're not microscopic, they're a few centimetres long and they can live a couple of years. The krill poo is raining down on everything below, which is providing a huge amount of food source for the sea floor. That alongside the 24-hour daylight in the summer means that there's a huge amount of food sinking down to the bottom of the sea and the diversity there is tens of times higher than you get at the surface, where you end up with about 20,000 species. Lots of them are brand new to science that are all eating what's raining down from above. It's quite an amazing environment.
Sally - It sounds like life below the ice is a lot nicer than actually life above the ice, the bit that we picture when we think of the Antarctic. Is that right?
Huw - Definitely. It's quite stable, but also there's this regular food supply. You don't need to be all fighting over one bit of food, there's enough food for everybody. But also it looks in places a bit like a coral reef and there's a lot of colour and diversity and two metre tall sponges that live for thousands of years. You've got all sorts of amazing filter-feeding animals and ones that eat the mud. And then at the surface, the places we think about, it's a really harsh place where everything's killing each other to stay alive because they're in a place where it's boom and bust, summer and winter, and even the ducks on the sub-Antarctic Islands of South Georgia eat flesh because there's no plant material for them to eat in the winter. So it's quite a harsh place to be if you're at the surface, but actually quite a nice place, if you can cope with the cold water at the bottom of the sea.
Sally - I'm sorry. Flesh-eating ducks?
Huw - Yes, the South Georgia Pintail, the world's only flesh-eating duck.
Sally - That is a nightmare I never knew I had until now.
Huw - It is pretty horrible. It is almost, it's not a dog-eat-dog, but it's a duck-eat-duck world out there almost in South Georgia. Because if you go to the beaches, there will be birds waiting for seals to be born so they can start attacking and eating them, or penguins coming ashore being eaten by seals as they come in. It is like a 24/7 David Attenborough documentary of everything eating each other.
Nessa - Will the deep Antarctic be protected from global warming? Will we see that those ecosystems remain more intact or will even that be affected?
Huw - So you're definitely right that the shallow waters around Antarctica are some of the fastest warming waters on Earth and we're losing things like sea ice. So indirectly they'll be affected by things like the sea ice disappearing because this food that rains down very often, a lot of the species are dependent on the sea ice over winter. If that's missing, you'll have less krill or you'll have less phytoplankton. So there's less food, but also those deep waters are warming. It's like when Antarctica is warming in the middle of the continent that you go from -50ºC to -48ºC or something. It still feels very cold and for us that seems like it's not a big change, but actually for some of these animals that are very specially adapted to cold water, the idea that something else could come in and compete with them, even with a small amount of warming, could be a bigger danger than the actual warming itself.