The Belgica 121 expedition to the Western Antarctic Peninsula: a high resolution biodiversity census

Study Extent

The expedition took place between Feb 23 and March 24 , 2019. The Australis departed from Ushuaia (Argentina) on Feb 23rd and arrived at the first sampling station (Melchior Islands) on Feb 27th after crossing the Drake passage in strong headwinds. The last station was completed on March 20 and the expedition returned to Ushuaia on March 24 , a total of 22 days was devoted to the sampling effort, including birds and marine mammals observations. The sampling area focused on the West Antarctic Peninsula (WAP) and extended from the Berthelot Islands to the SW to Enterprise Islands to the NE and included a total of 15 stations. Certain stations were exhaustively sampled (see Table 1, in bold) while others were partially worked out as timing, priorities, anchoring and weather allowed. Metchnikoff Point (MP) was visited in order to check the status of historic monument #45.

Sampling

By design, the expedition was aimed to focus on carrying out a detailed biodiversity census, from the intertidal to the subtidal zones (up to 20m) in stations along the Gerlache Strait. The stations were chosen for their contrasting conditions in terms of exposure to glaciers influence, to different water masses (Drake, Gerlache Strait, etc...), and geomorphology. Multiple gears were deployed (see Table 3), combining traditional instruments and modern techniques, and the team mostly included young scientists who were acquainted to using several techniques. Each team had a specific project (see specific section, “Work at sea and preliminary results”) and was able to help others during sample processing stages. The initial stages of the expedition were exploratory (one full station would need up to 4 days to be completed) and were followed with more efficient sampling (1.5 – 2 days per station). Opportunistically, certain stations were partially sampled in function of the priorities and weather/anchoring conditions.

Quality Control

In the framework of the B121 expedition, data was aggregated and organized to ensure optimal use in the future for data publication in authoritative repositories and sample management. A series of data types were collected pertaining to navigation, weather conditions and sampling efforts (both biological and oceanographic). General procedures: • Logbooks: hard copies of logbooks were completed on a daily basis by the B121 team. Data was organized in 4 different logbooks: sample, events, photo, diving. Logbooks were digitized and backed up on a daily basis. • Spreadsheets: data from the logbooks was entered in dedicated spreadsheet on a daily basis by two members of the B121 team: Charlène Guillaumot and Bruno Danis. A quality control (QC) was performed on the fly and feedback was given to the researchers on an adhoc basis. • Backup procedures: digital data and samples were backed up on a daily basis on 2 computers and 2 external hard drives. Sample (biodiversity) data: Sample data was gathered in MS Excel spreadsheets, specially prepared for the expedition. The structure of the spreadsheet is based upon the Darwin Core (DwC) standard, expanded for specific data and sample management needs. A template of the spreadsheet is provided in annex for future use by other users. Media data: Large amounts of video data were gathered in the framework of the expedition, both for outreach and research purposes. Underwater footage was taken by Bruno Danis and Henri Robert using a Remotely Operated Vehicle (ROV: OpenROV Trident). The footage was used essentially for exploration and dive site confirmation purposes. Aerial footage was shot by Franz Heindler, Camille Moreau and Bruno Danis using two DJI Mavic Pro drones, for documentation purposes. Documentary footage was mostly shot by Franz Heindler and other members of the team. For more details, see the dedicated section below. Data publication: In the spirit of the Antarctic Treaty, Art. 3.1.c, the data emerging from the Belgica 121 sampling efforts will be made openly and freely available, in the best possible time limits and will follow the standards, policies and norms of behavior as established by the Scientific Committee on Antarctic Research (SCAR). In particular, raw biodiversity data will be shared using dedicated, community-driven platforms such as the biodiversity.aq initiative. Processed data will be made available through scientific publications and through the Belgica 121 website (www.belgica121.be).

Method steps

1. Full description of the methodologies is available from the B121 expedition report: http://belgica120.be/wp-content/uploads/2019/05/B121-Cruise-report.pdf Briefly, for the macro and mega benthos survey, the diversity analysis was conducted using various sampling gears and investigation means as a necessary preliminary step to further ecological analyses, from individual species systematics to trophic and community analyses. Most common and key species (engineers or top predators) of the surveyed shallow water habitats (between 5 and 20 m depth) could be observed and identified during the dives, some of them sampled by hand picking, or identified on video transects. This first inventory was widely complemented by samples collected with a Rauschert dredge, Van Veen grab and amphipod trap. For the soft sediments biodiversity, samples for meiofauna assemblage structure (taxa diversity, nematodes diversity, biomass), were collected at each location by divers either by means of perspex push cores (3.6 cm diameter, quantitative) or by surface sediment scooping (qualitative).Where the sediment characteristics allowed core sampling, the sediment was sliced in different layers profiles (0-1 cm, 1-2 cm, 2-5 cm 5-10 cm) for the whole core depth. At least three replicates were taken for the meiofauna characterisation at each location dive event. For the intertidal works, two sampling procedures were used to characterise the biodiversity and abundance on each site: (1) 10 quadrats (25cm X 25cm) were randomly disposed at the low tide level (Figure 28). Presence and abundance of each species (morphotypes) were recorded within each quadrat and specimens were preserved in 96% ethanol for further identification and analyses; (2) to obtain a better overview of the total biodiversity, an exploration (1 hour) in the vicinity of quadrats was also done to look for any species not found inside the quadrats. Fish biodiversity was addressed using three methods: (1) angling with hooks, line and sinker, (2) gill nets, and (3) a cylindrical fish trap or fyke. Angling took place with standard commercial fishing rods, braided fishing line, and rigs (Sabikis) equipped with multiple hooks of varying sizes, and small, colorful lures, luminescent plastic beads, and weights at the end in depth of 5 – 50 m. Hooks were sometimes baited with fish, mollusk or shrimp and used actively (jigging during daytime from the ship or zodiacs) or passively (fixed to the ship overnight). Two types of gill nets were used, measuring approximately 18 m in width and 1.5 m in height and with 4 cm and 8 cm mesh size (stretched), respectively. Nets were set in depths of 10 – 30 m and usually perpendicular to observed currents. The fish trap was deployed for at least 8 h in depths of 10 – 30 m, baited with fish, mollusks, or shrimp. Finally, continuous monitoring of birds and marine mammals (species identification and headcount) was performed from the bridge or a spot offering the best visibility on deck. Bird/mammal standard counts are 30 min non-stop observation with binoculars for identification (if required) and age/sex determination when possible. A 300 mm tele objective camera is used for documentation and identification of species that pose identification issues in the field (e.g. Catharacta spp., Pachyptila spp.). GPS ship position and climatic conditions are recorded at each start and end position of counts. Counts are performed during daylight (from dawn to dusk), while visibility permitting (counts must be stopped when visibility is poor due to heavy fog or precipitation) to avoid bias in animal detection and subsequent false population estimates.

Specimens were collected in the intertidal zone and the subtidal zone (max depth: 20m). Meiobenthos and megabenthos classes were analysed in particular. Identification of specimens is still ongoing, combining morphological analyses by expert taxonomists and a genetic approach where possible.

1. Abyssorchomene plebs
2. Acodontaster
3. Aequiyoldia eitghtsi
4. Algae
5. Amphipoda
6. Anemone
7. Arctocephalus gazella
8. Aselotta
9. Asteroidea
10. Austrodoris sp
11. Aves sp
12. Balaenoptera bonaerensis
13. Bathydraconidae
14. Bivalvia
15. Bryozoa
16. Catharacta maccormicki
17. Catharacta sp.
18. Chaenocephalus aceratus
19. Charcotia obesa
20. Chionis albus
21. Cnidaria
22. collembola
23. Cuenotaster involutus
24. Cumacea
25. Cyclocordia antarctides
26. Daption capense
27. decapoda
28. Diomedea exulans
29. Diplasterias brucei
30. Distaplya cylindrica
31. Echinodermata
32. Eucarida
33. Eusirus sp
34. Fregetta tropica
35. Fulmarus glacialoides
36. Gastropoda
37. Glyphoperidium bursa
38. Gobionotothen gibberifrons
39. Granaster
40. Granaster nutrix
41. Green Algae
42. Henricia
43. Himantothallus
44. Holothuroidea
45. Homaxinella balfourensis
46. Hydrurga leptonyx
47. Iridea
48. Isopoda
49. Krill
50. Labidiaster
51. Lagenorhynchus cruciger
52. Larus dominicanus
53. Laternula elliptica
54. Lepidonotothen nudifrons
55. Leptonychotes weddellii
56. Lobodon carcinophaga
57. Lugensa brevirostris
58. Lysasterias
59. Lysasterias sp
60. Macronectes giganteus
61. Margarella sp
62. Marjorella
63. Megaptera novaeangliae
64. Micale cf acerata
65. Mollusca
66. Mysidacea
67. Nacella concinna
68. Nematoda
69. Nemertea
70. Neosmilaster georgianus
71. Notothenia coriiceps
72. Notothenia rossii
73. Nudibranchia
74. Oceanites oceanicus
75. Odontaster roseus
76. Odontaster validus
77. Ophionotus
78. Ophionotus victoriae
79. Ophiuroidea
80. Ostracoda
81. Pachyptila desolata
82. Pachyptila sp.
83. Pagodroma nivea
84. Paraceradotus gibber
85. Parbolasia corrugata
86. Parborlasia corrugatus
87. Pelecanoides urinatrix
88. Penguin sp.
89. Perknaster
90. Phalacrocorax brandsfieldensis
91. Phoebetria palpebrata
92. Plathyhelminthes
93. Polychaeta
94. Polyplacophora
95. Pomacochrines kerguelensis
96. Porifera
97. Procellaria aequinoctialis
98. Procellaria cinerea
99. Psilaster charcoti
100. Pterodroma mollis
101. Pycnogonida
102. Pygoscelis antarcticus
103. Pygoscelis papua
104. Pygoscelis sp.
105. Sphaerema
106. Stauromeduse
107. Sterechinus neumayeri
108. Sterna vittata
109. Tanaidacea
110. Terebellidae
111. Thalassarche chrysostoma
112. Thalassarche melanophrys
113. Trematomus bernacchi
114. Trematomus bernacchii
115. Trematomus newnesi
116. Tunicata

The sampling area focused on the West Antarctic Peninsula (WAP) and extended from the Berthelot Islands to the SW to Enterprise Islands to the NE and included a total of 15 stations. Certain stations were exhaustively sampled while others were partially worked out as timing, priorities, anchoring and weather allowed. Metchnikoff Point (MP) was visited in order to check the status of historic monument #45. The birds and marine mammals survey was carried out all along the expedition and includes the whole expedition track, from Ushuaia (AR) to the WAP.