Albatross, penguin and krill research in Antarctica
In the Antarctic region, a great deal of research is being conducted by national Antarctic programmes including the UK’s, Australia’s and Japan’s on understanding species in the air, on the ground and in the sea and how their species are interconnected without variables including human impacts and climate change.
The future of albatross numbers in Antarctica
Albatrosses cover vast distances when foraging for food: Even during breeding seasons albatrosses can go from sub-tropical to Antarctic waters on trips covering up to 10,000 km over the space of 10 to 20 days. Many species of albatrosses, including the wandering and grey-headed albatrosses from the Southern Ocean south of Australia and South Georgia, migrate long distances with some travelling right around Antarctica. In addition to the impressive distances they travel the wandering albatross also have claim to being the largest of all ocean bird species with a wing-span of 2.5-3.5 metres in flight. The wandering albatross breeds on six Sub-Antarctic Island groups and also has colonies in the Indian Ocean and on South Georgia Island in the South Atlantic Ocean. However, with 15 of the world’s 22 albatross species threatened with extinction and seven others considered to be ‘near-threatened’ by the IUCN, the British Antarctic Survey (BAS) are monitoring three species of albatross located in South Georgia, which are declining at between 2 to 4 percent per annum.
Long-term monitoring of albatrosses
This monitoring programme has been long-standing with BAS scientists since the 1960s monitoring albatross populations at Bird Island, South Georgia; a place considered to be home to the largest and most studied albatross colonies in the world. Over the decades scientists have monitored return rates of ringed birds giving data on breeding frequency and survival rates, while GPS trackers and geolocator devices give a picture of the vast areas of ocean covered by the birds in their search for food. It is important data required to monitor the health of albatross species as they are a grand bird, being the largest of all seabirds and also the longest living with some reaching 60+ years old. It is their long lifespan that makes their species vulnerable as they do not breed until they are around 10 years old. Most species breed annually however nine species, including the wandering albatross, lay only one egg every two years and it takes over a year for a chick to leave the nest. As such even a small increase in death rates of adult albatrosses can severely impact chick survival rates.
Penguin counts in Antarctica
Long-term monitoring by BAS of penguin populations, particularly in the sub-Antarctic and Antarctic Peninsula have revealed fluctuations in specie numbers with Adelie penguin numbers dipping over the past three decades while in contrast the King penguin has increased from a few hundred in the 1920s to almost half a million today. In more southerly waters Emperor penguin numbers have experienced a significant decline with some colonies experiencing a decline in numbers of up to 50 percent with one northerly colony on the Antarctic Peninsula almost disappearing. To understand why penguin numbers are fluctuating BAS scientists are focusing their efforts on understanding how food supply and available nesting sites impact population numbers.
The link between sea ice penguin numbers
One finding is that BAS scientists, in collaboration with U.S. scientists, found sea ice plays a major role in the decline of penguin numbers as krill – which is the staple diet of not only penguins, but seals and whales too – spend their early stage of life grazing on phytoplankton located on the underside of floating sea ice. As such there is a correlation between Adelie population numbers and reductions in sea ice and associated food supply. Nonetheless, this relationship does not hold for all penguin species: While rapid warming temperatures on the Western Antarctic Peninsula have seen sea-ice cover reduce by around 40 percent over the past 30 or more years leaving ice-dependent penguin species vulnerable to further warming on the continent, other species less dependent on ice, including Chinstrap penguins, can thrive with reductions in ice increasing their number of breeding sites and food supplies. Nonetheless, this outcome is not guaranteed as Chinstrap population numbers have declined over the past few decades.
To understand more about penguins BAS has developed satellite and tagging systems to track penguins onshore and in the sea. One BAS research station – Bird Island Research Station – has developed a gateway for the resident penguin colony to enter and exit. As tagged penguins pass through the gate scientists can record the tag number, time and direction of travel which enables researchers to estimate how long the birds spend foraging in the sea. Meanwhile a joint BAS-Japan National Institute of Polar Research programme observed penguins underwater with miniature cameras attached on the back of individual penguins. In addition the programme attached GPS trackers to penguins enabling scientists to eventually build up an understanding of the reasons behind the success or failure of penguin colonies as well as build up a greater understanding of the Antarctic ecosystem.
Analysing past dinners of penguins
Australian scientists have attached small GPS trackers to the feathers on the backs of Adelie penguins to determine where they are foraging. These trackers have been attached to penguins across Australia’s research stations in the continent enabling scientists to study simultaneously penguin foraging behaviour in three areas and determine how natural variability in the marine environment impacts foraging efforts, particularly the impact of variable sea ice on foraging.
Meanwhile, Australian researchers from the Australian Antarctic Division have begun studying the historical feeding habits of Adelie penguins and the impacts of ocean acidification on phytoplankton and bacteria. Scientists will survey abandoned penguin sites to excavate ancient penguin droppings to determine how their diets have changed over time and what impacts climate and fishing will have on feeding habits of the penguins in the future. For instance the research aims to find whether Adelie penguin diets have changed in the coast from krill to fish-based diets, from which future population numbers can be estimated for Adelie colonies. Meanwhile, the researchers will explore the effects of ocean acidification on microbes across six 650-litre tanks which will model different carbon dioxide concentrations in the Earth’s atmosphere.
A focus on krill
Antarctic krill is a shrimp-like crustacean that can grow to 6 cm long and is a vital food source for fish, whales, seals, penguins and other sea birds.
Krill is also a product for feeding farmed fish and a nutrient-supplement to humans. To keep an eye on krill and understand how it plays a vital role in the ocean’s ecosystem BAS has implemented a long-term monitoring programme that estimates krill stock. An important aspect is that krill stock fluctuates naturally and in some years it can become scarce, with krill predator population numbers fluctuating in response. To understand the impacts of climate change BAS scientists are conducting research on how changes in temperature, ocean acidification and changes in sea-ice cover impact krill stocks. An important aspect of krill research is determining the exact connection between krill and predators as the Antarctic fur seal population at South Georgia has rapidly increased after years of over-harvesting despite fluctuating levels of krill.