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Science News News about the main scientific activities

Large-scale and long-time experiment testing the sensitivity of polar cod

Polar cod is a key component of Arctic marine food webs, connecting lower levels of the food web with those at the top by being an important food for sea birds and marine mammals. From a management perspective, it is therefore important to understand how sensitive polar cod is to potential pollution, which would provide us with an idea of the consequences an oil spill would have for the marine food web in the Arctic.

Recent research shows that polar cod eggs and larvae are sensitive to very low levels of crude oil. Adult polar cod, on the other hand, have been shown to efficiently break down toxic oil components and tolerate certain levels of oil exposure. However, in the event of an oil spill during the polar night, adult fish have depleted the majority of their energy reserves in order to produce good quality eggs and sperm, leaving little energy for the fish to combat the toxicity of oil compounds and withstand a major oil spill.

Nansen Legacy researchers are experimentally investigating the effects of crude oil exposure on polar cod in the spawning period during the Arctic winter. Illustration: Leah Strople

To test the effects of a winter oil spill on polar cod reproduction, Nansen Legacy postdoctoral fellow, Ireen Vieweg (UiT), brought many hundreds of live polar cod to Tromsø from a cruise in Hinlopen in 2018. In the aquarium facilities of UiT, the fish have been held in several large tanks under cold, dark and food deprived conditions since December, when they were exposed to low levels of crude oil. Since then, Nansen Legacy researchers have closely followed the fish’s physiological responses to the crude oil exposure, as well as their energy investment into reproduction. The experiment will run for five months and terminated around Easter.

Read more about the experiment on Forskning.no

New algal cultures from the Barents Sea and Arctic Ocean

Nansen Legacy postdoctoral fellow, Luka Šupraha (UiO), has isolated 100 monoalgal strains from the Nansen Legacy cruise in August 2018. The strains are now being characterized genetically and morphologically in the electron microscope and will be placed taxonomically by phylogenetic analyses.

Sixty-six strains are diatoms, 18 are dinoflagellates, 5 are chlorophytes, 5 are cryptophytes, one is a haptophyte and six are picoalgal strains which are not yet taxonomically assigned. Seventy of the strains were isolated from ice stations in the Arctic Ocean and 30 from the open water stations in the Barents Sea.

Their DNA sequences will be used to connect genotypes to morphotypes and to improve the reference databases used during metabarcoding analyses to reveal the protist community composition. New species for science will be described and their biogeographical distribution examined, to assess if any taxa are endemic to the Arctic.

Strains are available upon request for all Nansen Legacy participants, and will eventually be openly available for everyone through the Norwegian Culture Collection of Algae, after they have been properly characterized.

The cruise season starts soon!

Six Nansen Legacy cruises are planned for the coming year, with the first cruise taking place already in May. The goal of the Technology test cruise outside Runde in May is to test and eventually improve instruments and platforms, which are essential for the objectives of Nansen Legacy. The instruments include autonomous underwater vehicles (AUV) and ocean gliders, which are highly fragile and complex instruments, necessitating cross-disciplinary and cross-institutional collaboration, integration and tests.

From early August onwards, the Nansen Legacy will investigate the seasonal dynmaics of the northern Barents Sea ecosystem through four cross-disciplinary cruises, covering especially also the dark and less studied winter season. An additional cruise is allocated to service the oceanographic moorings north and east of Svalbard.

(Photos successively from the top: Rudi J. M. Caeyers, Peter Leopold, Bente Edvardsen, Pål G. Ellingsen)

If you have Nansen Legacy information to be included in the next newsletter, contact nansenlegacy_admin@uit.no

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