Maria Pia Nardelli, Corentin Guilhermic, Christine Dupuy, Hélène Howa, Eleonora Fossile, Agnès Baltzer, Aurélia Mouret, Meryem Mojtahid. (2022). Seasonal and interannual variability of benthic foraminiferal faunas under the influence of a tidal glacier.
Abstract: Kongsfjorden (Svalbard archipelago, Arctic) is subjected to intensifying environmental gradients resulting from the confrontation of fresh waters issued from tidal glacier melting and newly invasive Atlantic waters. Along a 12 km-long transect from the Kronebreen glacier front to the central fjord, Fossile et al. (2022) identified, during summer 2018, three foraminiferal biozones, responding to decreasing disturbances linked to the proximity of the tidal glacier front (i.e., high water turbidity, freshwater, and sediment inputs, reduced organic fluxes). Close to the glacier terminus (proximal biozone), few stress-tolerant or opportunistic species were present in high abundances indicating high physical and geochemical stresses on the benthic fauna. At about 6–8 km off the glacier front (medial biozone), reduced turbidity and increased organic fluxes resulted in a higher diversity and high abundances of phytodetritus-indicators. The distal biozone, at 12 km from the glacier front, was characterised by species typical of environments influenced by Atlantic waters and a relatively well diversified fauna, due to glacial reduced stressful conditions. The comparison of these assemblages with the ones observed at the same stations in spring and summer 2021, shows low interannual variability and a seasonal contrast in the proximal biozone higher than in the distal one. Stable C and N isotopes measured on the cytoplasm of target species show similar signals for a same species at different seasons and diverse trophic positions among species. This suggests that some indicator species can be used to identify changes in the trophic functioning of the ecosystems, related to seasonal or long-term changing inputs from the glacier melt waters. Overall, our results suggest that benthic foraminiferal communities can be effective bioindicators to monitor the influence of seasonal calving cycles and ongoing long-term retreat of tidewater glaciers induced by climate change in Kongsfjorden. The characteristic calving pattern of the Kronebreen, however, makes highly difficult to link the observed interannual faunal variability to glacier velocity or front retreat. Longer faunal time-series are needed to get a better signal.
Programme: 1223
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Mojtahid M., Fossile E., Santoni S., Husum K., Streuff K., Forwick M., Howa H., Nardelli MP. (2022). Benthic foraminifera as tools to reconstruct past tidewater glacier dynamics: A case study from Kongsfjorden (Svalbard).
Abstract: Located at the interface between terrestrial and marine systems, high latitude glaciated fjords are sensitive spots to current and past climate change. Kongsfjorden is located on the western part of the Svalbard archipelago and is characterized by steep environmental gradients, due to the dynamics of the tidewater glaciers, and the inflow of warm Atlantic Water (AW). Here we analyze fossil benthic foraminiferal assemblages in two main sediment cores in order to reconstruct past environmental changes in link with these environmental gradients. Sediment core 10JM-GLACIBAR-GC01, located in front of a surge-type tidewater glacier (Kronebreen complex) in the inner Kongsfjorden, represents a historical record spanning the period from 1950 to 2010 AD. In this record, we tested relationships between taxonomic and functional diversity metrics and the reconstructed distance from the glacier front. We observed a general increase in foraminiferal fluxes and diversity with the progressive glacier retreat, confirming a positive benthic response to reduced glacier-induced disturbance through time. This historical record confirms therefore the successful use of diversity metrics as proxies for tidewater glacier retreat. A study of a second sediment core, NP07-13/58-GC, spanning the last 3000 years and located in the central Kongsfjorden, was initiated to reconstruct the two end-members relationship between AW inflow and glacier retreat using benthic foraminiferal assemblages and diversity metrics applied in the historical record. The preliminary results show that until 1.6 cal ka BP and between 800 and 500 yrs cal BP, a low diversity and high relative abundances of glacier proximal species characterized the assemblages. According to the developed diversity metrics models, this suggests that the glacier grounding line/ice sheet was advanced by about 10 km compared to its position during the mid XXth century. From 1.6 to 0.8 cal ka BP and between 500 and 200 yr cal BP, taxonomic diversity increased, suggesting decreased glacial influence at the core site (in the central Kongsfjorden). Additionally, the most recent part of the record (500 – 200 yr cal BP) recorded increased relative abundance of the AW indicator Adercotryma glomeratum, suggesting increased influence of the AW carried by the West Spitsbergen Current in the central Kongsfjorden. These ecological observations need further investigations and comparison with published studies from Kongsfjorden and other Svalbard fjords. Investigations with multivariate analyses and Generalised Additive Models could help better interpret the patterns observed in term of species composition and general diversity.
Programme: 1223
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Delmotte M., Coulon A., Ramonet M., Gest L., Marquestaut N., Mekies D., Hazan L, Lopez M., Kouyaté M., Tulet P. (2022). Greenhouse gases measurements in Southern Ocean on board the Marion Dufresne.
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Antoine, A. (2022). Beneath the Antarctic sea-ice: Fine-scale analysis of Weddell seal (Leptonychotes weddellii, Lesson 1826) behaviour and predator prey interactions, using micro-sonar data and video recordings in Terre Adélie.
Abstract: The sea-ice zone constitutes the breeding and foraging habitat of large populations of ice-based species, pointing at its far-reaching ecological importance. Given its sensitivity to global warming, there is an urgent need for determining how predators use their environment, to understand and predict their response to climate variability. New perspectives are offered by miniature animal-borne sensors: in 2019, 3 sonar tags were deployed on lactating female Weddell seals for 7 days in Terre Adélie to study 3D animal movement and fine-scale predator-prey interactions. Lactating females demonstrated central-place foraging strategy, with restricted foraging area (3-6 km) and mostly benthic dives (97% of dives, visualising the seafloor on echograms). Their foraging effort was constrained by the presence of their pup: females spent most of their time hauling out (77% of overall recordings). The time spent underwater was mostly dedicated to diving (>5m) (1.36 on 7days, 854 dives recorded), as opposed to shallower under ice activities (<5m) (0.3 days). A total of 331 prey capture attempts (PrCA) were recorded, using tri-axial acceleration data, of which 125 prey (4.7 ± 1.5 cm on average) were identified by the sonar on 78 dives (4.24 ± 3.99 PrCA/dive). All PCA occur on the seafloor, at shallower depth than usual Weddell seal records (88 ± 30 m). Lactation is therefore a period of physiological stress, with foraging limited by pup compared with other parts of the life cycle. Using functional principal component analysis and model-based clustering on high resolution dive data, we found that PrCAs occur mostly in 2 of the 5 dive shape clusters. Foraging dives are characterised by W or V shape and high sinuosity, at the scale of the dive (W shapes) or during the ascent phase (V shapes). During the approach phase, seals constantly scan the area by regularly moving their head left to right, suggesting opportunistic behaviour. Shallow phase behaviour was studied using video recordings (2h recorded per seal). Seals spent most of their time interacting with their pup (33%) and
hauling-out (42%). Most mother-pup interactions were on sea-ice (71%), as opposed to underwater (29%). The results suggest lactating females’ energy budget changes, with lactation being a period of physiological stress. This period of feeding pressure might put them at higher risk regarding adaptation to environmental variability.
Programme: 1182
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Félix Lévesque-Desrosiers, William Bonilla, Florent Domine, Simon Thibault. (2022). Autonomous Optical Sensor to Study the Evolution of Snow Density in Polar Environment (Vol. Proceedings of Imaging and Applied Optics Congress).
Abstract: A system to study the evolution of snow density is presented here with an emphasis on the system itself and on the efforts to make a robust system for harsh environments. The metric to deduce the density of the snow is the measurement of the concentration of ambient air oxygen using a tunable diode laser spectroscopy technique: the first harmonic phase angle wavelength modulation spectroscopy. For greater robustness, the system is equipped with an embedded calibration system and is built for a smart power consumption.
Programme: 1042
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Fillion D., Dominé F., Couture Rm. (2022). Identification de composés organiques volatils issus de la photochimie de la matière organique dans les lacs nordiques.
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Meagan Dewar, Michelle Wille, Amandine Gamble, Ralph Vanstreels, Thierry Boulinier, Adrian Smith, Arvind Varsani, Norman Ratcliffe, Jennifer Black, Amanda Lynnes. (2022). The Risk of Avian Influenza in the Southern Ocean: A practical guide.
Abstract: Advice from Avian Influenza experts suggests that there is a high risk that Highly Pathogenic Avian Influenza will arrive in the Southern Ocean 2022/23-2024/25 austral summers. Since the beginning of 2022, the increasing intensity of highly pathogenic avian influenza (HPAI) H5N1 outbreaks has resulted in the death of hundreds of thousands of seabirds in the Northern Hemisphere, around the Atlantic and Pacific Oceans and southern Africa. The SCAR Antarctic Wildlife Health Working Group (AWHWG) is highly concerned about the likely arrival and subsequent impact HPAI H5N1 might have on Southern Ocean wildlife. Due to the heightened risk of HPAI being introduced to Antarctica during the the 2022/23 Austral summer by migrating seabirds, the AWHWG recommends that: People working with or close to wildlife should assume that HPAI will arrive in the sub-Antarctic and Antarctica and take precautions to protect themselves when working around wildlife (including appropriate PPE) and maintain the highest biosecurity to prevent transmission between wildlife aggregations. All National Programmes (NPs) and tourism operators should monitor colonies for signs of H5N1 before approaching, especially in migratory species such as skuas, gulls and giant petrels. Tourists should not enter colonies and high wildlife density areas with suspected HPAI and NPs should conduct risk analysis as to which activities need to continue. A more detailed protocol on how to assess wildlife aggregations for HPAI prior to a visit and what to do if HPAI is detected should be provided to all stakeholders physically present in Antarctica this season. If you detect signs of HPAI, you should report this to your permit issuer. Videos of affected animals are very helpful for experts to help determine whether or not this is HPAI. Operators should refresh themselves with and review all biosecurity and any response guidelines to unusual/mass mortality events. This document aims to: Outline the likely risk to Southern Ocean taxa (a more technical assessment will follow in a separate document). Suggest which risks can be mitigated in light of human activity, transmission into and out of Antarctica and the sub-Antarctic regions through all operators as well as movements between sites within the Southern Ocean (primarily for science and tourism), Start discussion with National Programmes about ongoing monitoring for disease and consequences.
Keywords: Antarctica, Avian Influenza, Infectious disease, Seabirds, sub-Antarctic
Programme: 1151
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Marianna Chimienti, Akiko Kato, Olivia Hicks, Frédéric Angelier, Michaël Beaulieu, Jazel Ouled-Cheikh, Coline Marciau, Thierry Raclot, Meagan Tucker, Danuta Maria Wisniewska, André Chiaradia, Yan Ropert-Coudert. (2022). The role of individual variability on the predictive performance of machine learning applied to large bio-logging datasets (Vol. 12).
Abstract: Animal-borne tagging (bio-logging) generates large and complex datasets. In particular, accelerometer tags, which provide information on behaviour and energy expenditure of wild animals, produce high-resolution multi-dimensional data, and can be challenging to analyse. We tested the performance of commonly used artificial intelligence tools on datasets of increasing volume and dimensionality. By collecting bio-logging data across several sampling seasons, datasets are inherently characterized by inter-individual variability. Such information should be considered when predicting behaviour. We integrated both unsupervised and supervised machine learning approaches to predict behaviours in two penguin species. The classified behaviours obtained from the unsupervised approach Expectation Maximisation were used to train the supervised approach Random Forest. We assessed agreement between the approaches, the performance of Random Forest on unknown data and the implications for the calculation of energy expenditure. Consideration of behavioural variability resulted in high agreement (> 80%) in behavioural classifications and minimal differences in energy expenditure estimates. However, some outliers with < 70% of agreement, highlighted how behaviours characterized by signal similarity are confused. We advise the broad bio-logging community, approaching these large datasets, to be cautious when upscaling predictions, as this might lead to less accurate estimates of behaviour and energy expenditure.
Keywords: Behavioural ecology Ecological modelling Ecophysiology Machine learning
Programme: 1091
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Étienne Vignon, Lea Raillard, Christophe Genthon, Massimo Del Guasta, Andrew J. Heymsfield, Jean-Baptiste Madeleine, Alexis Berne. (2022). Ice fog observed at cirrus temperatures at Dome C, Antarctic Plateau (Vol. 22).
Abstract: As the near-surface atmosphere over the Antarctic Plateau is cold and pristine, its physico-chemical conditions resemble to a certain extent those of the high troposphere where cirrus clouds form. In this paper, we carry out an observational analysis of two shallow fog clouds forming in situ at cirrus temperatures – that is, temperatures lower than 235 K – at Dome C, inner Antarctic Plateau. The combination of lidar profiles with temperature and humidity measurements from advanced thermo-hygrometers along a 45 m mast makes it possible to characterise the formation and development of the fog. High supersaturations with respect to ice are observed before the initiation of fog, and the values attained suggest that the nucleation process at play is the homogeneous freezing of solution aerosol droplets. This is the first time that in situ observations show that this nucleation pathway can be at the origin of an ice fog. Once nucleation occurs, the relative humidity gradually decreases down to subsaturated values with respect to ice in a few hours, owing to vapour deposition onto ice crystals and turbulent mixing. The development of fog is tightly coupled with the dynamics of the boundary layer which, in the first study case, experiences a weak diurnal cycle, while in the second case, it transits from a very stable to a weakly stable dynamical regime. Overall, this paper highlights the potential of the site of Dome C for carrying out observational studies of very cold cloud microphysical processes in natural conditions and using in situ ground-based instruments.
Programme: 1013
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G. J. Sutton, C. A. Bost, A. Z. Kouzani, S. D. Adams, K. Mitchell, J. P. Y. Arnould. (2021). Fine-scale foraging effort and efficiency of Macaroni penguins is influenced by prey type, patch density and temporal dynamics (Vol. 168).
Abstract: Difficulties quantifying in situ prey patch quality have limited our understanding of how marine predators respond to variation within and between patches, and throughout their foraging range. In the present study, animal-borne video, GPS, accelerometer and dive behaviour data loggers were used to investigate the fine-scale foraging behaviour of Macaroni penguins (Eudyptes chrysolophus) in response to prey type, patch density and temporal variation in diving behaviour. Individuals mainly dived during the day and utilised two strategies, targeting different prey types. Subantarctic krill (Euphausia vallentini) were consumed during deep dives, while small soft-bodied fish were captured on shallow dives or during the ascent phase of deep dives. Despite breeding in large colonies individuals seemed to be solitary foragers and did not engage with conspecifics in coordinated behaviour as seen in other group foraging penguin species. This potentially reflects the high abundance and low manoeuvrability of krill. Video data were used to validate prey capture signals in accelerometer data and a Support Vector Machine learning algorithm was developed to identify prey captures that occurred throughout the entire foraging trip. Prey capture rates indicated that Macaroni penguins continued to forage beyond the optimal give up time. However, bout-scale analysis revealed individuals terminated diving behaviour for reasons other than patch quality. These findings indicate that individuals make complex foraging decisions in relation to their proximate environment over multiple spatio-temporal scales.
Programme: 394
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