This story was originally Appeared in hakai magazine is part of climate desk collaboration.
At Fulham Strait off the west coast of Greenland, Veronique Merten encountered invading infantry.
Merten was using environmental DNA to study the region’s biodiversity. This is a method that allows scientists to figure out which species live nearby by sampling small pieces of genetic material such as scales, skin and feces. And here is Shishamo, a region of the Arctic Ocean 400 kilometers north of where they have been seen so far.
And they were everywhere.
Small baitfish found in the North Atlantic and Pacific Ocean are avid colonists. Merten, a marine ecologist at the GEOMAR Helmholtz Marine Research Center in Kiel, Germany, says capelin can expand its range very easily when sea conditions change.
It is difficult to estimate animal abundance based solely on the amount of DNA in water.not yet In the Merten sampleThe most frequently encountered species was capelin, much more common than typical Arctic fish such as the Greenland halibut and Arctic gangite. For Merten, evidence of capelin in such abundance this far north is a bold sign of Atlanticization, a disturbing Arctic phenomenon.
The Arctic Ocean is warming rapidly and the Fram Strait is warmed up to about 2°C But Atlanticization is more than just an increase in temperature, it is a process that reshapes the physical and chemical conditions of the Arctic Ocean.
Due to the ocean’s global circulation patterns, water routinely flows from the Atlantic to the Arctic. This exchange occurs primarily in the deep ocean, with ocean currents carrying warm and relatively saline Atlantic waters northward. However, this warm Atlantic water does not mix well with the relatively cold, fresh surface waters of the Arctic. Freshwater is less dense than salty water, so Arctic water tends to float on top, trapping salty Atlantic water deep below the surface.
But as sea ice disappears, the surface of the Arctic Ocean is heating. The barriers between the layers have deteriorated, making it easier for Atlantic waters to mix into the upper layers. This initiates a feedback loop in which warmer surface waters melt more sea ice, and more sunlight on the sea surface heats the water, melting the ice and further mixing the waters of the Atlantic and Arctic. there is That is Atlanticization. The Arctic Ocean will change from colder, fresher and ice-covered to warmer, saltier and increasingly ice-free.
Merten’s discovery of abundant capelin in the Fram Strait, as well as DNA from other Atlantic species that extend well beyond their normal range, such as tuna and squid, demonstrate how rapidly Atlanticization is occurring. It provided further evidence that And the impact can be devastating.
For example, in the Barents Sea off the coast of Russia, Long-term study abroad It shows the grim picture of how Atlanticization destroys Arctic ecosystems. As the Barents Sea warms and becomes more salty, Atlantic species are “migrating and occupying,” says Maria Fosheim, a fishery ecologist at the Norwegian Institute of Oceanography, who led the study.
According to Fosheim, fish communities in the Barents Sea have migrated 100 miles north in just nine years. [previous studies] I had foreseen. By the end of the study in 2012, Fosheim found that Atlantic species had spread across the Barents Sea, almost pushing out Arctic species.
Merten’s findings suggest that the Fram Strait may be headed in a similar direction. However, as this study is the first to examine fish diversity in the Fram Strait, it is unclear how recent these changes really are. “We need these baselines,” says Merten. “It may be [capelin] It had already happened there many years ago, but no one checked. ”
Either way, they are there now. The question is, what will emerge next?
