Stephen Roberts

Volcanic eruptions may have periodically wiped out Antarctic penguin colonies

Long-term changes in climate and sea ice coverage aren’t the only problems that Antarctica’s penguins face: Volcanoes can also take their toll, a new study suggests. Consider gentoo penguins (Pygoscelius papua), which have a major breeding colony (image) on Ardley Island off the Antarctic peninsula. The orange-billed birds first appeared on the island about 6700 years ago, and previous studies indicate that the climate and sea surface temperatures in the region have been good to them thus far. But sediment cores drilled from a 7300-square-meter lake on the island—which today collects runoff that includes prodigious amounts of penguin guano as well as material eroded from the island’s bedrock—tell a different story. At three times since the birds arrived, major eruptions of a volcano on Deception Island, which lies about 120 kilometers away, have cloaked Ardley Island with centimeters-thick layers of ash that later washed into the lake, the researchers report in Nature Communications. It’s not clear whether each of those ash layers chronicles a single large eruption or a closely spaced sequence of smaller ones. Regardless, guano-free followed by guano-poor sediments left in the wake of these three eruptions suggest that breeding penguins were wiped out—or abandoned the island for posteruption intervals ranging between 400 and 800 years. Thick layers of ash would have made it hard for the birds to breathe, compromised the immune systems of adult and hatchling penguins, and may have prevented adults from collecting pebbles that they needed to construct their nests, the researchers suggest.