Chick numbers at a key emperor penguin breeding site in the Ross Sea of Antarctica have dropped sharply in a year.
Korea Polar Research Institute (KOPRI) said on the 19th that the number of emperor penguin chicks counted at the Coulman Island breeding site in the Ross Sea fell from about 22,000 last year to around 6,700 this year. The drop is about 70%.
The Ross Sea, home to more than 1 million Adélie penguins and tens of thousands of emperor penguins as well as whales, seals, seabirds, and krill, is considered the world's largest marine protected area.
Researchers identified a large iceberg blocking the front of the breeding site as the cause of the decline in emperor penguins in the Ross Sea. Coulman Island is known as the largest emperor penguin breeding site in the Ross Sea, but this year it saw an unusual, steep drop that was not clearly observed at nearby sites.
KOPRI researchers Kim Jong-woo and Kim Yu-min confirmed during on-site surveys last month that a giant iceberg about 14 kilometers long was blocking a main gateway connecting the breeding site and the sea. The institute said the iceberg's area is equivalent to about 5,000 soccer fields.
An analysis of satellite data suggests the iceberg broke off from the Nansen Ice Shelf in March this year, drifted north, and by late July had blocked the entrance to the breeding site.
The problem was that it coincided with the emperor penguin's breeding schedule. After laying eggs in June, females leave the eggs with males and head to the ocean to hunt, then return two to three months later around hatching to feed the chicks. But researchers said it is highly likely that many adults failed to deliver food on time after the iceberg cut off their route home.
Drone photos also yielded clues. Dozens to hundreds of adults were observed unable to return to the breeding site due to the iceberg cliff, and fecal stains that appeared to be traces of their long stay were also identified. Kim Jeong-hoon, who led the research, said, "About 30% that survived likely moved along other routes not blocked by the iceberg and supplied food."
There are also concerns that if the iceberg stays in the same place for a long time, breeding itself could be disrupted. Kim said, "If the passage remains blocked, emperor penguins may move to other breeding sites." Park Jin-gu, who analyzed satellite data, said, "The trajectory of the iceberg that split from the Nansen Ice Shelf shows it passes by other major habitats," adding, "The collapse of ice shelves could pose a potential threat to emperor penguins and other Antarctic species."
The research team plans to formally report the case next year to international bodies such as the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).
Shin Hyeong-cheol, director of Korea Polar Research Institute (KOPRI), said the situation "shows the unpredictable risks that climate change brings to the Antarctic ecosystem."