| 1. |
- Balazy, Kaja, et al.
(författare)
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Molecular tools prove little auks from Svalbard are extremely selective for Calanus glacialis even when exposed to Atlantification
- 2023
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Two Calanus species, C. glacialis and C. finmarchicus, due to different life strategies and environmental preferences act as an ecological indicators of Arctic Atlantification. Their high lipid content makes them important food source for higher trophic levels of Arctic ecosystems including the most abundant Northern Hemisphere's seabird, the little auk (Alle alle). Recent studies indicate a critical need for the use of molecular methods to reliably identify these two sympatric Calanus species. We performed genetic and morphology-based identification of 2600 Calanus individuals collected in little auks foraging grounds and diet in summer seasons 2019-2021 in regions of Svalbard with varying levels of Atlantification. Genetic identification proved that 40% of Calanus individuals were wrongly classified as C. finmarchicus according to morphology-based identification in both types of samples. The diet of little auks consisted almost entirely of C. glacialis even in more Atlantified regions. Due to the substantial bias in morphology-based identification, we expect that the scale of the northern expansion of boreal C. finmarchicus may have been largely overestimated and that higher costs for birds exposed to Atlantification could be mostly driven by a decrease in the size of C. glacialis rather than by shift from C. glacialis to C. finmarchicus.
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| 2. |
- Jørgensen, Mads R V, et al.
(författare)
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Neutron and X-ray investigations of the Jahn-Teller switch in partially deuterated ammonium copper Tutton salt, (NH4)2[Cu(H2O)6](SO4)2
- 2017
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Ingår i: Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials. - 2052-5192. ; 73:1, s. 87-93
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Tidskriftsartikel (refereegranskat)abstract
- The structural phase transition accompanied by a Jahn-Teller switch has been studied over a range of H/D ratios in (NH4)2[Cu(H2O)6](SO4)2 (ACTS). In particular, single-crystal neutron diffraction investigations of crystals with deuteration in the range 50 to 82% are shown to be consistent with previous electron paramagnetic resonance (EPR) experiments exhibiting a phase boundary at 50% deuteration under ambient pressure. Polycrystalline samples show that the two phases can co-exist. In addition, single-crystal neutron and polycrystalline X-ray diffraction pressure experiments show a shift to lower pressure at 60% deuteration versus previous measurements at 100% deuteration.
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| 3. |
- Schultz, Mads, et al.
(författare)
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Calanus helgolandicus : more than a guest in the north?
- 2023
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Ingår i: Journal of Plankton Research. - : Oxford University Press. - 0142-7873 .- 1464-3774. ; 45:1, s. 33-36
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Tidskriftsartikel (refereegranskat)abstract
- Molecular identification of Calanus helgolandicus has revealed a more northern distribution for this boreal species than previously reported. We investigated an Arctic fjord to determine if local reproduction is taking place. Combining time series data from depth stratified sampling with molecular tools for species identification, we found C. helgolandicus from all stages throughout the year including males and females as well as a nauplius. These findings constitute strong evidence that C. helgolandicus is reproducing north of the Arctic Circle and their role in the ecosystem should be investigated further.
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