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

Bruno Danis

The study area was primarily the Western Antarctic Peninsula in the Southern Ocean. B121 took place between February and March 2019, sampling 15 stations in 22 working days in an area extending from Berthelot (65°19.751 S, 64°08.263 W) to Enterprise (64°32.420 S, 61°59.899 W) Islands.

The overarching objective of the expedition was to gather samples and data to help build a benchmark to better understand the response of shallow benthic communities to variable glacial regimes in a fast-warming region of the Southern Ocean, the WAP. The collected samples are expected to help refine insights gained in the plasticity/resilience of these communities in the framework of the RECTO/vERSO projects (http://rectoversoprojects.be). The objective was tackled by using a multi-faceted approach, matched by the complementary competences of the scientific crew and sampling gear. The expedition was a unique opportunity to address a series of underlying scientific/logistic questions. Amongst these questions, the expedition focused on testing the concept of using a nimble platform for Antarctic marine biology fieldwork and its potential to fill knowledge gaps with a limited environmental impact, mapping the marine habitats in selected locations of the Gerlache Strait and assessing different biodiversity levels in various locations of the WAP, from the supratidal to 20 m depth.

The Belgian Science Policy Office (BELSPO): the bulk of the funding of the expedition was channelled through two research projects funded by BELSPO, RECTO (promoter: Isa Schön, Royal Belgian Institute of Natural Sciences) and vERSO (promoter: Bruno Danis, Université Libre de Bruxelles). The Cabinet Marcourt (Federation Wallonia-Brussels – Research, Education) supported the expedition for functioning and various equipment. The Belgian Federal Public Service Health, Food Chain Safety and Environment funded the ship time necessary to the visit of historic monument N°45 dedicated to the Belgica expedition, led by Adrien de Gerlache. The Fund for Scientific Research – FNRS and the Research Foundation – Flanders (FWO) have funded travel expenses. The B121 team also acknowledges financial support from the Fonds Léopold III and the Royal Belgian Zoological Society.

The expedition took place between 23 February and 24 March 2019. RV Australis departed from Ushuaia (Argentina) on February 23 and arrived at the first sampling station (Melchior Islands) on 27 February after crossing the Drake Passage. The last station was completed on 20 March and the expedition returned to Ushuaia on 24 March, a total of 22 days being devoted to the sampling effort, including bird and marine mammal observations. The sampling area focused on the WAP and extended from the Berthelot Islands to the SW to Enterprise Islands to the NE and included a total of 15 stations. Nearly half the stations were exhaustively sampled according to the initial protocol established (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 at the request of the Belgian Federal Service Food, Health and Environment Foundation.

The expedition aimed to focus on carrying out a detailed biodiversity census of shallow areas, from the intertidal to the subtidal zones (up to 20 m depth) at 15 stations within the Gerlache Strait. The stations were chosen for their contrasting conditions in terms of exposure to glaciers influence, iceberg scouring, to ocean water masses and currents (Drake Passage, Gerlache Strait etc.), geomorphology, penguins colonies and direct anthropogenic stressors (tourism and maritime traffic). Multiple types of gear were deployed (see Table 2), combining traditional marine ecology instruments (traps, nets, grabs, ...) and modern techniques (drones, ROVs). The team was mostly composed of young scientists who were acquainted with the use of several techniques. Each team had a specific project 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 by more efficient sampling (1.5–2 days per station). Opportunistically, certain stations were partially sampled as a function of priorities and weather/anchoring conditions.

In the framework of the B121 expedition, data were aggregated and organised 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 were organised in four different logbooks: sample, events, photo and diving. Logbooks were digitised and backed up on a daily basis. Spreadsheets: data from the logbooks were entered in a dedicated spreadsheet on a daily basis by two members of the B121 team: Charlène Guillaumot and Bruno Danis. Quality control (QC) was performed on the fly and feedback was given to the researchers on an ad hoc basis. Backup procedures: digital data and samples were backed up on a daily basis on two computers and two external hard drives. Sample (biodiversity) data: Sample data were 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 this spreadsheet is provided in an annex for future use by other users. Identifications were carried out in the field and taxonomic data were cross-checked against the content of the World Register of Marine Species Taxon Match tool (http://www.marinespecies.org/aphia.php?p=match). For specimens we were not able to identify, help is sought from taxonomic experts and the dataset will be updated accordingly. 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. Macrophotography of the most common species was carried out by Quentin Jossart. 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 behaviour 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).

Full description of methodologies is available from the B121 expedition report (Danis et al. 2019): 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 sediment biodiversity, samples for meiofauna assemblage structure (taxa diversity, nematode 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 layer 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 work, two sampling procedures were used to characterise the biodiversity and abundance on each site: (1) 10 quadrats (25 cm × 25 cm) were randomly disposed at the low tide level. 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 the 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, colourful lures, luminescent plastic beads and weights at the end in depths of 5–50 m. Hooks were sometimes baited with fish, mollusc 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, molluscs 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 telephoto lens was 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 were recorded at each start and end position of counts. Counts were performed during daylight (from dawn to dusk) and only during good visibility (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.

The sampling area focused on the Western Antarctic Peninsula (WAP) and extended from Berthelot Island to the SW to Enterprise Island to the NE and included a total of 15 stations (see Fig. 1). 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.

Figure 1.  

General map of the sampling area. Red rectangles: complete stations; orange rectangles: partial stations; green rectangle: historic monument visit. Modified after MAP “Brabant Islands to Argentine Islands”, British Antarctic Survey, Edition 1, 2008.

-66 and -54 Latitude; -68 and -62 Longitude.

Specimens were collected in the intertidal and subtidal zones (max depth: 20 m). 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.

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