Antarctic life – penguins, seals and fish
Antarctic life is tough and full of surprises. Penguins return to the ice in the middle of winter to lay their eggs. Seals use cracks in the ice to keep their pups safe. Fish have antifreeze proteins to survive in the icy, cold waters. Scientists are keen to piece together the Antarctic food web to better understand the interconnections and to enable smart conservation decisions.
Introducing Antarctic life – penguins, seals and fish
RNZ science communicator Dr Claire Concannon shares some insights into the fourth episode of her Voice of the Sea Ice podcast series, More life! This short video explores research on Weddell seals, penguins and other Antarctic animals. Claire interviews scientists researching how changes in sea ice and climate will impact these animals.
Select here to view the video transcript, and copyright information.
Cape Crozier
In July 1911, Apsley Cherry-Garrard, Edward Wilson and Henry Bowers took 19 days to travel from Cape Evans to the emperor penguin rookery at Cape Crozier – pulling sleds first across the sea ice of McMurdo Sound and then across the Ross Ice Shelf, in pitch black darkness and bitingly cold temperatures.
Their goal was to collect some emperor penguin eggs for science, but their experience was what inspired the name of Cherry-Garrard’s memoir – The Worst Journey in the World.
Today, the trip from Scott Base to Cape Crozier takes just 1 hour by helicopter.
Antarctic life – penguins and seals – podcast
RNZ science communicator Dr Claire Concannon introduces us to some key species found in Antarctica from her fourth episode of six in the Voice of the Sea Ice podcast series. Claire meets scientists researching Weddell seals and Adélie and emperor penguins.
Select here to view video transcript and copyright information.
It’s a trip that Dr Michelle LaRue of the University of Canterbury is happy to take, especially in the 24-hour sunlight of November 2024.
Cape Crozier, on the eastern end of Ross Island, is quite a special place, she says, inhabited by hundreds of thousands of Adélie penguins, up to 2,000 emperor penguins, and about 50 Weddell seals.
Emperor penguins are some of the most badass animals in the world, because they go through the most extreme situations.
The emperor penguins use the sea ice as their nursery. This is where they return to in the middle of winter to lay their eggs. Instead of nests, the egg is cared for on the feet of the male penguins, who huddle together against the winter cold. It’s something Michelle believes makes penguins particularly ‘badass’. “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.”
Associate Professor Michelle LaRue at Cape Crozier
Dr Michelle LaRue is researching emperor penguins at Cape Crozier in Antarctica.
As per Antarctic regulations, Michelle and the photographer are specially permitted to get this close to the Antarctic wildlife.
Michelle is interested in whether Weddell seals and penguins have their own niches – dividing up the territory and food – or if they compete for the same resources.
To investigate this, Michelle and her team are attaching satellite tags to 10 Adélie penguins, 10 emperor penguins and 10 Weddell seals. The tags give real-time information on where the predators are going and how deep they are diving. Their initial results appear to show that her niche partitioning theory is correct – they don’t tend to overlap in the areas where they are fishing. The team will be back next year to tag more birds and seals to gather more data to be sure.
While there, they collect seal whisker and penguin feather samples as well as samples of the microalgae found on the bottom of the sea ice plus some seal scat, or poo. These samples help them check the health of the animals and enable them to investigate where everybody sits on the who-eats-who tiers of the Antarctic food web.
Monitoring seal stress
The seal scat will also be used by another colleague, University of Canterbury PhD candidate Arek Aspinwall, as a control for his research on seal stress.
Outside of Scott Base, towering shapes and sheets of sea ice folding over form where the ice is being squashed against Ross Island. The icy structures provide shelter from the wind, and the cracks through the ice allow access to the ocean below.
Weddell seals by Scott Base
Weddell seals near Scott Base. In the background, you can see some of the pressure ridges the seals use for safety and feeding during pupping season. In the middle of the image is a hole left by a seal. A seal can lie about for 5–6 hours and their body heat melts the snow underneath it, which then refreezes, leaving a frozen outline of the seal on the ground.
Photo by Claire Concannon.
This is ideal for Weddell seals, explains Arek.
“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, can’t get this far into the Sound at this time of year. So these pups are pretty safe.”
Weddell seals show up in large numbers in January and February, and they spread out again when the ice starts to freeze in March.
In the morning, many of the mother seals have gone fishing so they can produce milk for their rapidly growing pups. Adult Weddell seals reach between 400–500 kg. When the pups are born, they weigh about 30 kg. Within 6 weeks, they will be up to around 100 kg.
Arek is outside Scott Base daily to collect the seal scat and urine and to investigate whether construction activities at Scott Base are stressing the seals that live nearby.
“We accept that we always have an impact,” he says, “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 unacceptable impact.”
Fish and the Antarctic food web
Professor Steve Wing, Director of the Royal Institute for the Conservation of Marine Protected Area Research, University of Otago, is working with a team in the Ross Sea. They’re trying to figure out what is eating what in the web of Antarctic life and then tracing the ways that nutrients get put back into the system.
Marine ecologist Professor Stephen Wing
Professor Stephen Wing at the Marine Studies Centre at the University of Otago.
Photo by Claire Concannon.
There are estimated to be more than 320 species of fish in the Southern Ocean around Antarctica. Steve and his team are focused on three key species: the crocodile icefish, the silverfish and the toothfish.
Antarctic toothfish
The Antarctic toothfish (Dissostichus mawsoni) can grow to over 2 metres long, weigh more than 100 kilograms, and may live up to 50 years. It is the target of bottom longline fishing. Commercially fished toothfish are marketed as Chilean sea bass.
Toothfish are commercially fished in the Ross Sea outside of the Ross Sea Marine Protected Area. The Ross Sea Marine Protected Area Agreement expires in 2052, after 35 years. Alongside issues like declines in sea ice extent, we need to have a good understanding of Antarctic food web connections and how different parts of the food web impact abundance in other areas to inform further decision making and regulation.
Crocodile icefish after being prepared
This shows what a Crocodile icefish looks like after it has been prepared for photographing.
Steve and his team also want to know how crocodile ice fish are linked to other parts of the food web. To date, they’ve found that penguin colonies are heavily reliant on young crocodile icefish as a food source.
Another key finding has been understanding how much Weddell seals rely on toothfish as a food source, particularly right before they go through pupping.
Steve’s team use a variety of methods to investigate food web connections. These include:
chemical analysis of the fish eye lens to figure out what the fish was eating throughout its different life stages
isotopic analysis of fish muscle tissue samples, which helps place them on the correct tier in the food web
analysis of some fish otoliths or ear bones – as the otolith grows, it stores information about the chemistry of the water the fish was in at that time.
Combining all the data gives a clearer picture of the whole Antarctic food web structure.
Learn more about the research Steve is leading and the variety of methods used by the scientists in the long version of the podcast More life! on RNZ.
Related content
Voice of the Sea Ice is a six-part RNZ podcast series that delves into science research and adventure in Antarctica. Explore the other episodes:
A land of ice and ambition: Learn about different types of ice, crevasses and the work to map safe routes across Antarctica for scientists and their equipment.
Antarctic life – microalgae: Introduces microalgae (zooplankton) that live on the bottom of the ice and among the platelet ice layer just below it
Antarctic life – penguins, seals and fish: Scientists are investigating the Antarctic food web to better understand the interconnections.
Changing times in Antarctica: Scientists talk about what sea ice decline means for the world and how they feel about it.
Climate change – where to? Human-induced climate change is impacting Earth’s global systems, including ice melt in Antarctica. What is the world doing to combat it? Where does New Zealand fit in, and are we doing our bit as a nation?
Further explore life in Antarctica further with these articles:
For resources that provide a deeper exploration of other ice forms in Antarctica, go to Icebergs and Glaciers. Antarctic sea ice decline and modelling explains sea ice around Antarctica, and Climate change, melting ice and sea level rise explores ice sheets and ice shelves.
Take a look at the citizen science project Crabeater Seals – Tomnod, which was led by Dr Michelle LaRue.
Activity ideas
In the activity Animal and plant adaptations, students learn about animal and plant adaptations in Antarctic species and use these ideas to design their own unique animal or plant.
Get students involved as citizen scientists in the Penguin Watch – Zooniverse project.
The activity Build a marine food web looks at marine food webs in temperate waters, and Making a food web is specific to Antarctica.
The teacher resource Antarctica – literacy learning links lists selected articles from the Connected and School Journal reading series that support the science concepts when teaching about Antarctica.
Useful links
Meet other seals and penguins with Peregrin Hyde in this RNZ podcast about South Georgia Island.
In Best journey in the world from the RNZ Voices from Antarctica series, Alison Ballance travelled to Cape Crozier with a team from NIWA studying emperor penguins.
Acknowledgement
This resource is adapted from the work of Dr Claire Concannon for the RNZ podcast series Voice of the Sea Ice. The series was made with travel support from the Antarctica New Zealand Community Engagement Programme.
