Fatty acids in zooplankton Nansen Legacy Q3

Study Extent

Nansen Legacy main transect along 34°E in the Northern Barents Sea and adjacent Arctic Basin from 76 to 82°N

Sampling

Samples of 24 zooplankton taxa including copepods, krill, amphipods, pteropods and gelatinous species were collected at six stations (P1, P2, P4, P5, P6, P7), using MIK nets (1200 μm with 500 μm cod end) and WP3 net (1000 μm) for large taxa, Macroplankton trawl for mostly Thysanoessa spp. (multiple mesh sizes along the net, tapering to 8 mm at its end), Bongo net (180 μm) and Multinet (180 μm) for copepods (all species), and WP2 net (90 μm) for small copepods. Samples were sorted into the lowest possible taxonomic level, and/or stage/size groups (where possible) onboard the ship and immediately frozen at -80 ºC.

Method steps

1. Fatty acids were analysed at the Alfred Wegener Institute, Bremerhaven, Germany. All samples were freeze-dried for at least 24 h prior to lipid extraction (-45 °C, 0.1 mbar). Zooplankton were homogenized mechanically using a Potter-Elvehjem homogenizer. Total lipids were extracted using a modified procedure from Folch et al. (1957) with dichloromethane/methanol (2:1, v/v). The extracted lipids were cleaned with 0.88 % potassium chloride solution and converted into fatty acid methyl esters (FAMEs) and free fatty alcohols derived from wax esters by transesterification in methanol, containing 3 % concentrated sulfuric acid, at 80 °C for 4 h. After a subsequent hexane extraction, the FAMEs and alcohols were separated split-less via gas chromatography. FAMEs were identified via standard mixtures and total lipid content was quantified with an internal standard (23:0) that was added prior to lipid extraction. Folch, J., Lees, M., and Stanley, G.H.S. (1957). A simple method for the isolation and purification of total lipides from animal tissues. J. Biol. Chem. 226(1), 497-509

Copepods, krill, amphipods, pteropods, cnidarians, ctenophores, chaetognaths, appendicularians

1. Calanus glacialis
2. Calanus hyperboreus
3. Calanus finmarchicus
4. Metridia longa
5. Microcalanus spp.
6. Pseudocalanus spp.
7. Oithona similis
8. Paraeuchaeta spp.
9. Meganyctiphanes norvegica
10. Thysanoessa inermis
11. Thysanoessa longicaudata
12. Themisto abyssorum
13. Themisto libellula
14. Clione limacina
15. Limacina helicina
16. Bougainvillia superciliaris
17. Catablema vesicarium
18. Beroe cucumis
19. Mertensia ovum
20. Eukrohnia hamata
21. Parasagitta elegans
22. Sagitta maxima
23. Oikopleura vanhoeffeni

Nansen Legacy main transect along 34°E in the Northern Barents Sea and adjacent Arctic Basin from 76 to 82°N