“A lake in Antarctica transformed from ocean water to freshwater over approximately 6,000 years.”

This implies that a former ice sheet, with different configuration from that of today, was responsible for their formation. The channels are not thought to be the result of the rapid drainage of a former subglacial lake, due to the lack of a potential site upstream for such a lake. Instead, Rose et al. interpreted their formation as resulting from the transfer of surface meltwaters to the ice-sheet bed, during a time when the West Antarctic Ice Sheet was temperate and subject to significant amounts of seasonal surface melt.

Despite its seemingly stable conditions, the lake occasionally experiences abrupt changes. During fieldwork in 2019, Andersen and colleagues observed a rapid increase in Unter-See's water levels. The team later analyzed elevation data from NASA’s ICESat-2 and confirmed that the 2-meter rise was caused by a glacial lake outburst flood from nearby Lake Ober-See.

While they previously thought that the ice over Mercer Lake had been stable for up to hundreds of millennia, this new work confirms the lake was connected to the ocean about 6,000 years ago, and the West Antarctic Ice Sheet was smaller than it is today. The microbes in the lake are feeding off 6000-year-old carbon introduced when this region was still connected to the ocean. Mercer Lake is now a freshwater subglacial lake.

The freshwater lakes were formed when fjords were truncated or behind ice dams. These lakes offer a continuum of salinity and physical conditions in which to study the allopatric evolution of marine-derived organisms.

Hundreds of lakes exist beneath the Antarctic ice sheet, and very few have ever been explored by scientists. Now, an international research team has published their findings from an ambitious effort to drill over 1,000 meters into the ice to sample the life hidden in one known as Mercer Subglacial Lake. The Mercer Subglacial Lake expedition marks only the second time in human history that scientists have successfully accessed a subglacial lake without contamination.

Long Lake is located approximately 300 m from the shoreline at an elevation of only 14 m a.s.l. Its first isolation is estimated to have occurred at 6.445 ± 40 14C yr BP (7.360 cal yr BP). This marks a transition from marine to terrestrial environment at Lake Long site during the mid-Holocene isostatic uplift of the South Shetland Islands, due to deglaciation and tectonics.

However, the new findings confirm that the lake was connected to the ocean around 6,000 years ago, when the West Antarctic Ice Sheet was significantly smaller than it is today. The team discovered that microbes in the lake are feeding off carbon that is 6,000 years old, a time when the region was still connected to the ocean.

Although Mercer Subglacial Lake is a freshwater lake, the sediment samples revealed that less than 10,000 years ago the ocean covered the area of the continent where the lake is today.

That research also shed light on the diverse microbial community within Mercer Subglacial Lake: Bacteria, archaea, and other microbes here obtain energy partly from carbon introduced some 6,000 years ago from a marine source when the lake was linked to the Southern Ocean as well as carbon from upstream sources in the subglacial drainage network, and also, via the process known as chemosynthesis, from minerals sourced from bedrock pulverized by the ice sheet.

Rising salt levels near Antarctica are altering ocean dynamics, drawing up warm water and accelerating sea ice loss, new satellite data reveal. A new study finds increasing ocean salinity near Antarctica is driving warmer water to the surface, which speeds sea ice melt and hinders winter ice formation.

A general late Holocene trend of declining lake salinity was evident in all three lakes, interrupted by one short-term high salinity event in Beall Lake. This general decline in salinity has been followed by a remarkable recent rapid increase in salinity in all three lakes in the last few decades.

Using data from ESA's SMOS satellite, scientists have revealed a surprising shift in the Southern Ocean – surface waters around Antarctica are growing saltier, even as sea ice is diminishing rapidly. This finding defies the norm because melting ice typically freshens ocean surface water.

Lake Vostok's prehistoric origins are a little murky, but for the past 15 to 20 million years (or so), the lake's been covered by ice. The Antarctic Ice Sheet contains a whopping 70 percent of all the fresh water on planet Earth. Lake Vostok is the biggest of the bunch.

Most are freshwater, but brackish to hypersaline systems may result from evaporation and evolution of trapped seawater. Lakes here are often chemically stratified (meromictic) where meltwater has overridden relic seawater.

In 1996, six years after drilling was started, a group of Russian and British scientists discovered the lake believed to be one of the largest fresh water reservoirs on the planet. Sealed from the Earth's atmosphere for millions of years, it may provide vital information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet.

Scientists have identified 85 previously unknown lakes hidden beneath Antarctica's ice using a decade's worth of satellite data. The newfound lakes are 'active,' meaning they periodically drain and refill, changing size and shape over months and years, the researchers said. This subglacial activity affects the stability of glaciers and their grinding movement over the Antarctic bedrock.

Antarctic subglacial lakes, such as Lake Vostok, formed millions of years ago under ice sheets and maintain salinity through geothermal melting and ice accretion processes, not a recent transition from seawater; no documented lake shows a full transformation from ocean water to freshwater in approximately 6,000 years.

Hidden beneath Antarctica’s ice is a strange lake that flips our understanding of life on Earth by thriving in complete darkness... The water itself has been sealed off from the surface for millions of years, creating an isolated ecosystem. No specific mention of a 6,000-year ocean-to-freshwater transformation.