Staying cool also has consequences: increased sea ice cover disrupts food web structure in East Antarctica-Data

Study Extent

Sampling took place in the surroundings of Dumont-d'Urville station (French Polar Institute Paul-Emile Victor - IPEV), on Petrels Island (Adélie Land, East Antarctica) during the austral summers of 2013-2014 (sampling dates: 22 - 26/01/2014) and 2014-2015 (sampling dates: 17/12/2014 - 12/01/2015). During these two austral summers, extreme sea ice conditions occurred, as fast ice did not undergo seasonal breakup for two successive years (ice thickness fluctuating between 40 and over 200 cm during summer, cf. supporting information S1). Two sampling sites were chosen. Site 1 ("Anse du Lion"; 140.003° E, 66.661° S) was visited during both sampling campaigns, while site 2 ("Cap des Eléphants"; 139.997° E, 66.667° S) was sampled only in 2014-2015. In both sampling campaigns, both sites were covered by a thick layer of fast ice (from around 100 to over 200 cm, supporting information S1), and holes were drilled to allow access to the sea

Sampling

Six items (producers or organic matter pools) were identified as potential food sources for primary consumers. Sympagic algae, that mostly occurred as several cm long filaments, were sampled by SCUBA divers by scraping the lower surface of fast ice. The dominant macroalgae, the large Phaeophyceae Himantothallus grandifolius and the Rhodophyceae Phyllophora antarctica, were hand-collected by SCUBA divers. Benthic biofilm was collected by scraping rocks in situ. It was scarce in 2013-2014 but extremely abundant in 2014-2015 (thick layer of several cm covering rocks but also macroalgae and sponges, supporting information S2). Seawater for suspended particulate organic matter (SPOM) was collected through the diving holes, at 10 m depth using a Niskin bottle. 195 Seawater was then pre-sieved to remove items larger than 5 mm, and filtered on pre-combusted (4h at 400 °C) glass fiber filters (Whatman GF/F, sieve size 0.7 μm). For each SPOM sample, 20 liters of seawater were filtered. Finally, samples of the abundant deposits of guano surrounding the extensive colonies of Adélie penguins (Pygoscelis adeliae) were hand collected on land, in vicinity of the diving holes.

Method steps

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1. Acodontaster
   rank: genus
2. Adamussium colbecki
   rank: species
3. Ammothea carolinensis
   rank: species
4. Benthic biofilm
5. Charcotia obesa
   rank: species
6. Decolopoda australis
   rank: species
7. Demospongiae
   rank: species
8. Diplasterias brucei
   rank: species
9. Flabegraviera mundata
   rank: species
10. Golfingia
    rank: genus
11. Harmothoe
    rank: genus
12. Hemigellius
    rank: genus
13. Heterocucumis
    rank: genus
14. Himantothallus grandifolius
    rank: species
15. Homaxinella balfourensis
    rank: species
16. Isotealia antarctica
    rank: species
17. Laternula elliptica
    rank: species
18. Margarella
    rank: genus
19. Marseniopsis
    rank: genus
20. Mycale acerata
    rank: species
21. Deontostoma
    rank: genus
22. Odontaster validus
    rank: species
23. Ophiura
    rank: genus
24. Parborlasia corrugatus
    rank: species
25. Perkinsiana
    rank: genus
26. Phyllophora antarctica
    rank: species
27. Polycirrus
    rank: genus
28. Pygoscelis adeliae guano
    rank: species
29. Saliasterias brachiata
    rank: species
30. Staurocucumis
    rank: genus
31. Sterechinus neumayeri
    rank: species
32. Suspended particulate organic matter
33. Sympagic algae
    rank: unranked
34. Trophonella longstaffi
    rank: species

East Antarctica, Adélie Land, Dumont-d’Urville research station