Canada’s sole remaining epishelf lake, characterized by freshwater floating on saltwater, has vanished, along with the distinct ecosystem it sustained, as per a recent study by scientists. Jérémie Bonneau, the study’s lead author and an assistant professor at Laval University in Quebec City, expressed sorrow over the loss, emphasizing that the Milne Fiord epishelf lake on Ellesmere Island in Nunavut was the final one of its kind in Canada.
The disappearance of this unique phenomenon underscores the impact of a warming climate on the Arctic region, according to Bonneau. While prior reports had already noted the demise of the lake, the new study, recently published in the journal Scientific Reports, delves into the specifics of its disappearance, declaring the irreversible loss as signaling a significant shift and the conclusion of a 4000-year era.
The formation of epishelf lakes involves glaciers acting as icy rivers that typically flow into the ocean, carrying meltwater with them. However, the Milne Fiord had been obstructed for millennia by the Milne Ice Shelf, preventing freshwater from entering the ocean and allowing it to accumulate atop the Arctic Ocean’s saltwater. The lake’s freshwater layer, initially measured in 1983 at a depth of 18 meters, akin to a six-storey building, had been accumulating for over 4000 years.
The lake’s dual layers hosted distinct ecosystems, with researchers finding minimal overlap between the freshwater and saltwater communities residing merely 20 centimeters apart. The unique environment supported a variety of organisms, including bacteria, viruses, and phytoplankton, unique to each layer and showcasing a rare ecological setup not found elsewhere.
Tragically, in 2020, the Milne Ice Shelf disintegrated off the coast of Ellesmere Island, leading to the collapse of the lake it sustained. Subsequent investigations revealed the rapid drainage of freshwater from the fiord within two months of the ice shelf’s breakup, resulting in the loss of the unique ecosystem. The demise of the lake highlights the transforming landscape of the Arctic due to climate change, with a warning that similar phenomena in Greenland and Antarctica may face a similar fate.
