[LUM#18] Arctic Mission

[LUM Magazine] - Published on May 2, 2023 in Science-Society

To determine whether the distribution ranges of marine fish are changing as a result of climate change, Loïc Sanchez sailed around the Baffin Sea, collecting environmental DNA samples along the way.

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2000 kilometers across the Baffin Sea from the Inuit community of Grise Fiord to Saint Pierre et Miquelon. This is the extraordinary voyage undertaken by Loïc Sanchez aboard Vagabond, a 15-metre sailing boat captained by seasoned explorer Eric Brossier.

A unique experience for the young PhD student from the Marbec laboratory¹. His mission? To predict changes in the distribution ranges of marine fish species. " We want to know whether, with climate change, species previously found elsewhere are now found in this area", explains Loïc Sanchez. Although scientists already have a great deal of data at their disposal, the young researcher points to a number of "holes in the picture".

"There are some very under-sampled areas and the poles are one of them, yet these are crucial data because the effects of climate change are particularly intense there." And most of the data available to scientists to date comes from direct observations underwater. A method
which has its limits: "for example, we can miss very shy species which hide from divers, or species which are too small and difficult to observe", explains Loïc Sanchez.

To flush out the shy ones, and fill in the gaps, Loïc Sanchez uses
the environmental DNA technique, which consists of filtering water samples to recover the DNA left behind by living organisms. This DNA is then compared with data from a reference database to determine which species it relates to. " This will enable us to assess the contribution of environmental DNA to the detection of additional species," explains Loïc Sanchez.

The PhD student took some 30 samples along the way, "data that is worth its weight in gold, because until now, there has never been any sampling there". Back on land, they are sent for analysis to start-up Spygen, to reveal which species inhabit the waters of this sea bordering the Arctic Ocean. " This information will be used to predict changes in fish
distribution areas under various climate change scenarios.