Several meters thick, the multi-year ice accumulates in an Arctic maritime area, the Nares Strait, where numerous fjords dump alluvial deposits and ice loaded with fertile elements. A team of researchers aboard the Amundsen is studying one of the planet’s best-preserved ice ecosystems, in anticipation of future changes.
The Canadian Coast Guard vessel Amundsen has been venturing into the summer waters of the Nares Strait between Canada and Greenland since August 8, with 78 scientists on board. She is heading as far north as possible to study the “last ice area”. The mission will end after 56 days at sea, when summer comes to a close. Although Amundsen is able to do this, the crew avoids having to break through the ice as much as possible. “From a practical point of view, it’s not ideal,” explains ocean biologist Mathieu Ardyna, project manager of the Refuge-Arctic mission, via videoconference. “The ship is looking for passages to enter bays and go up fjords.” Makinson, Dobbin, Archer, Newman, Cadogan… He has inspected some of them on both sides of the strait. “Each glacial valley works differently, and that promises great results,” adds Audrey Limoges, paleoceanographer at the University of New Brunswick, alongside Mathieu Ardyna, as the ship makes its way between the icebergs towards Greenland.
At the entrance to the folds of the coastline, the crew set to work. The first operation is to survey the generally poorly mapped seabed. “Next, we collect and analyze the water. It contains phytoplankton, nutrients, viruses and may contain heavy metals such as mercury,” explains Audrey Limoges. Scientists are wondering about the changes in dynamics that occur when glaciers retreat. “The particles discharged by rivers and glaciers change in nature and number,” she explains. “Thanks to optical measurements, we can assess the penetration capacity of light in the water column.”
Moving gradually upwards towards the freshwater plume of the fjords, nets are set out to collect zooplankton, jellyfish, fish… all links in the food chain. The chances of catching salmon returning from the Pacific, driven by the effects of climate change, are slim to none. “The strait is fed by water from the central Arctic Ocean. The phenomenon of ‘atlantification’ occurs in the Barents Sea, or similarly in the Chukchi Sea. Here, we’re still too far north to witness an invasion of species. Instead, we’ll be surprised by organisms that haven’t yet been inventoried in the Arctic, but whose range is naturally extending northwards”, explains Mathieu Ardyna. For example, the researcher has spotted a well-known alga further south, which clumps together in microscopic balls in the waters of the strait.
Despite the cold, Arctic ecosystems are active. “What controls productivity is mainly light and nutrients,” he explains. In summer, there can be 24 hours of daylight, unlike in winter. “As you approach the glaciers that end in the sea, you enter an active zone where freshwater pours in, laden with nutrients and sediments, creating plumes,” describes Audrey Limoges.
Beyond 80° latitude, the ship approaches the last areas of ice. “This is where multi-year ice is thought to persist longest in the future, although after a certain level of warming it is still likely to melt,” she points out. These patches of frozen sea are solid supports that let in light and contain nutrients. “Compression ridges can be five meters high, and inside them, interstices submerged at different depths are supports for life,” describes Mathieu Ardyna. “We want to understand how light gets through, how nutrients circulate and what exchanges there are with the seabed.” Mooring lines in operation since last year will be recovered in the coming days. They have captured particles traveling between the ice and the bottom.
The analysis of particles, molecules and fossils will enable scientists to reconstruct the ecosystems of the Holocene (11,000 years ago) and even the interglacial age (130,000 years ago). These periods experienced degrees of warming similar to those we are experiencing and may experience in the future. Understanding the long history of this Arctic refuge would help Inuit and Canadian institutions to continue managing the Tuvaijuittuq Marine Protected Area. According to Mathieu Ardyna: “This unprecedented effort will help strengthen conservation in this fragile region by helping to perpetuate the Tuvaijuittuq and Pikialasorsuaq Marine Protected Areas, and will enable the general public and younger generations to discover the importance, uniqueness and global role of these fascinating and threatened environments.”
Camille Lin, Polar Journal AG
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