Today, on the shores of the island of Ardley, there is a colony of penguin donkeys of about 5000 pairs. In the long run, this is the maximum number that has so far been achieved only three times. Mostly before they swept the volcanic eruption or covered the fine ash from the volcano. It is located near the Deception Island, 120 km away, which is still tectonic. The whole story of the "immortal" colony was then revealed by the Roberts, the explorer of the British Antarctic Station. Originally, he did not focus on penguins at all, but on the development of the quaternary climate.
Roberts's specialization is the period of Pleistocene and Holocene in which he seeks "answers" in the form of consequences of historical climate change. A useful tool is taken by the glacier nuclei that drifts along the coast from the archipelago of the South Shetland to the western tip of Antarctica. Together with his colleagues, he soon noticed a somewhat unusual sample of sediment from Ardley Island. The three and a half meter long borehole that covered the 8500 years of the past, was geographically distinct from the geochemical point of view. It contained a large amount of guano, bird bones, and volcanic ash.
Subsequent analysis has shown that the island has struck three massive eruptions in the past. The first time before 5300 (and then 4300 and 3000 years). They almost always "swept a penguin colony from the map". "Nevertheless, the colony never disappeared altogether, although its return to the original condition always lasted at least four to eight centuries," says Roberts. The volcano eruption force (VEI) on Deception Island compares to St. Helena's eruption in 1980, which was "economically speaking the most devastating volcanic eruption in American history." No less devastatingly, the explosion also impressed the local penguins.
"Toxic fly ash could kill them on the ground, a number of youngsters could literally be covered with ash in their nests," says Roberts. "The volcano also killed indirectly by reducing food availability and disturbing conditions throughout the island." It is clear from the sediment analysis that several animals have survived, probably because they were far off in the sea, at a hunt for food . "And some of them then fought in a volcanic wasteland and survived," says Roberts. He adds that the explosion probably did not occur at the peak of the breeding season. That would be even less to the survivors.
Deception Island knows about it today. Its eruptions are significantly weaker in the last two millennia. Last woke up in 1970, but penguins did not react to him. They remain faithful to their place, regardless of natural disasters.
Author: Radomír Dohnal
Source: Ekolist.cz
