Thousands of emperor penguin chicks die in massive catastrophe in Antarctica
Scientists said the colony, which was located at the edge of the Brunt Ice Shelf, has now collapsed and the adult birds are not showing any signs of trying to re-establish the population
A major catastrophe took place in 2016 in Antarctica's Weddell Sea. Thousands of emperor penguin chicks died after they drowned when the sea-ice on which they were being raised by their parents was destroyed due to severe weather.
Scientists said the colony, which was located at the edge of the Brunt Ice Shelf, has now collapsed and the adult birds are not showing any signs of trying to re-establish the population. It would probably be pointless for them to do so anyway because a giant iceberg is about to disrupt the site.
The team from the British Antarctic Survey (BAS) is the one that reported the staggering loss of birds. Dr. Peter Fretwell and Dr. Phil Trathan had noticed that the so-called Halley Bay colony has suddenly disappeared when they were looking through satellite images, BBC reported.
They said it is possible to spot the birds' excrement or guano, even from 800 kilometers above on the white ice and thus estimate the likely size of the gathering. The population in Brunt, which generally had an average of 14,000 to 25,000 breeding pairs for a few decades, basically vanished overnight. This particular concentration of birds was said to make up 5-9% of the global population.
Emperor penguins are the tallest and the heaviest of the penguin species and they require reliable patches of sea-ice to be able to breed. The sea-ice has to be able to last from April, when the birds arrive at the spot, until December, when their chicks normally fledge. If the essential sea-ice breaks up too early in the year, the chicks will not have the correct feathers in order to start swimming. This is what appears to have taken place in 2016.
Strong winds have hollowed out the sea-ice that stuck to the side of the thicker Brunt shelf in its creeks but it never reformed properly. This didn't happen in 2017 and it didn't happen in 2018 either. Fretwell said: "The sea-ice that's formed since 2016 hasn't been as strong. Storm events that occur in October and November will now blow it out early. So there's been some sort of regime change. Sea-ice that was previously stable and reliable is now just untenable."
The BAS team also believes that many of the adult breeding pairs have avoided breeding completely in the past couple of years or have moved on to new breeding sites across the Weddell Sea. A colony that exists about 50 kilometers away, close to the Dawson-Lambton Glacier, has seen a rise in its numbers in recent years.
Exactly why the sea-ice platform at the edge of the Brunt shelf not being able to reform is still unclear. There have been no obvious climate signals to point to in this scenario and the atmospheric and oceanic observations are the same. The shifting of the colony does illustrate, according to the team, the impact of losing Antarctic ice could have on the Emperor Penguins. This would also have consequences that extend beyond the penguins, said Dr. Michelle LaRue, who is an ecologist at the University of Canterbury in New Zealand.
She told BBC News: "They're an important part of the food web; they're what we call a mesopredator. They're both prey for animals like leopard seals but they also prey themselves on fish and krill species. So, they do play an important role in the ecosystem."
Dr. Trathan said: "What's interesting for me is not that colonies move or that we can have major breeding failures - we know that. It's that we are talking here about the deep embayment of the Weddell Sea, which is potentially one of the climate change refugia for those cold-adapted species like emperor penguins. And so if we see major disturbances in these refugia - where we haven't previously seen changes in 60 years - that's an important signal."
The Brunt Ice Shelf is currently being split by a crack that is getting larger by the day. The giant crack will eventually cause ice to break off from the main shelf and into the Weddell Sea and it is estimated that the iceberg will be the size of Greater London. This could, in turn, break up any sea-ice on the edge of the iceberg and the colony could be doomed at this particular site regardless of the tragedy in 2016. The investigation by the BAS team led by Dr. Fretwell and Dr. Trathan was published in the journal Antarctic Science.