The blog of Xeno, a slightly mad scientist
Lake Vostok, Antarctica’s biggest and deepest subsurface lake, might contain thousands of different kinds of tiny organisms — and perhaps bigger fish as well, researchers report.
The lake, buried under more than 2 miles (3.7 kilometers) of Antarctic ice, has been seen as an earthly analog for ice-covered seas on such worlds as Europa and Enceladus. It’s thought to have been cut off from the outside world for as long as 15 million years. But the latest results, reported in the open-access journal PLOS ONE, suggest that the lake isn’t as sterile or otherworldly as some scientists might have thought.
More than 3,500 different DNA sequences were identified in samples extracted from layers of ice that have built up just above the surface of the lake. About 95 percent of them were associated with types of bacteria, 5 percent of them had the hallmarks of more complex organisms known as eukaryotes, and two of the sequences were linked to a distinct class of one-celled organisms called archaea.
The sequences included close matches for various types of fungi as well as arthropods, springtails, water fleas and a mollusk. What’s more, some of the bacteria from the sample are typically found in fish guts — suggesting that the fish they came from may be swimming around in the lake.
Lake Vostok, which is 800 miles (1,300 kilometers) from the South Pole, is thought to have been open to the air and surrounded by a forested ecosystem during the warmer climate that existed more than 35 million years ago. “At that time, the lake (which might have been a marine bay) probably contained a complex network of organisms,” the researchers behind the PLOS ONE study suggest.
They say life forms could have been transported into the lake from the atmosphere until it was sealed up by ice, sometime around 15 million years ago.
Today, the buried lake measures 160 miles (250 kilometers) in length and 30 miles (50 kilometers) in width. Its depth is thought to average about a quarter of a mile (344 meters).
“While the current conditions are different than earlier in its history, the lake seems to have maintained a surprisingly diverse community of organisms,” the researchers wrote. “These organisms may have slowly adapted to the changing conditions in Lake Vostok during the past 15-35 million years as the lake converted from a terrestrial system to a subglacial system.” …
In 15 million years, what strange new creatures have evolved?