Nelson Mandela University’s long-term research on King penguins at Marion Island formed part of an international study which predicts that 70% of the sub-Antarctic seabirds could disappear by 2100, as a result of climate change.
The study found that warmer sea temperatures are shifting King penguins’ main food sources further south and, unless the penguins move too, they could starve.
“More than 70% of the world’s King penguin population form breeding colonies on Crozet, Kerguelen and Marion Island,” said Nelson Mandela University zoology senior lecturer Dr Pierre Pistorius, one of the co-authors of a paper on the study, which has been published in the prestigious journal Nature Climate Change.
The French-led study – which included researchers from Monaco, Italy, Norway, Austria and the United States – has also been important in shaping a new three-year collaborative study between South Africa and France, funded by the South African National Antarctic Programme (SANAP), to further investigate the impact of climate change on Marion Island’s seabird populations.
Pistorius, who heads the Marine Apex Predator Research Unit (MAPRU) at Nelson Mandela University, said King penguins rely on the Antarctic Polar Front – an upwelling front in the Southern Ocean, where cold Antarctic and warmer sub-Antarctic water meet, churning up nutrients and attracting enormous amounts of fish – as their main food source. In the breeding season, parents leave their chicks to swim 350km to 500km to the front, returning days later with food for their young.
But warmer seas are shifting the front further south – and the study predicts that the penguins will have to swim more than 700km, the maximum distance they can travel to find food without compromising the survival of their chicks, due to their own increased energy expenditure. The possible starvation of their chicks could lead to huge population crashes.
“The front moves from year to year depending on the temperature of the ocean – and we have already seen impacts in King penguin numbers in the years it has shifted further away from the breeding sites,” said Pistorius.
“What we have found at Marion Island is that King penguin numbers have actually been stable over the past years, but this study provides strong predictions about how it could all change in the future, if we don’t do something about global warming … It’s hard to imagine Marion Island without King penguins, but there is no doubt that climate change is causing major changes in the Southern Ocean.”
The study says King penguins could save themselves by moving to other islands further south, except they have strict habitat requirements, so a new home might be hard to find. To form a colony where they can mate, lay eggs and rear chicks over a year, they need tolerable temperatures all year round, no sea ice around the island, relatively smooth beaches – and a food source close by to feed their young.
The research team used high-tech modelling, based on genetic and demographic data, to reconstruct the changes in the worldwide penguin population throughout the last 50,000 years. What they found was that past climatic changes, causing shifts in marine currents, sea-ice distribution and Antarctic Polar Front location, have always been linked to critical episodes for the King penguins. However, they have always managed to overcome these, relocating during tough times.
However, they have never had to compete with rapid and irreversible changes in their environment caused by human activity.
The Polar regions are feeling the impact of climate change the most – and the Southern Ocean is also subject to commercial fishing.
“There are still some islands further south where King penguins may retreat,” says study co-author and co-supervisor Dr Celine Le Bohec, from the University of Strasbourg in France, “but the competition for breeding sites and for food will be harsh, especially with the other penguin species like the Chinstrap, Gentoo or Adelie penguins, even without the fisheries.
“It is difficult to predict the outcome, but there will surely be losses on the way. If we want to save anything, proactive and efficient conservation efforts but, above all, coordinated global action against global warming should start now.”
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