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Mojtahid M., Fossile E., Santoni S., Husum K., Streuff K., Forwick M., Howa H., Nardelli MP. (2023). Benthic foraminifera as tools to reconstruct past tidewater glacier dynamics: A case study from Kongsfjorden (Svalbard).
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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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Pauline Goulet, Yan Roper-Coudert, Christophe Guinet. (2021). Using on-animal sensors to study the Ocean and its inhabitants.
Abstract: Bio-logging is a methodological approach in which miniature data recording devices are temporarily attached to free-ranging animals to monitor their movement, behaviour and physiology, as well as the physical parameters of the environment directly surrounding the animals, turning them into bio-plateformes. Unsurprisingly bio-logging emerged from marine and polar studies where the monitoring of individuals in these harsh and remote places cannot be done using traditional approaches. Miniaturization and technological advances has meant that the range of species that can be instrumented, as well as the diversity of the questions that can be sought through bio-logging, are expanding fast. New sensors are constantly being developed, pushing further the limits of this field. Instrumented animals deliver information not only on their activities but also on the physical characteristics of the environments they go through. For instance, over the last two decades, loggers attached to deep diving seals have supplemented physical oceanographic measurements with hydrographic profiles from CTD loggers but also with new series of biological measurements. For examples, fluorescence and light sensors provided information on the concentration of phytoplankton in the euphotic layer; miniature echo sounders together with high sensitivity and fast responding light sensor to detect bioluminescence, brought considerable progress in detecting small size particles (>1-2 mm) such as marine snow, zooplankton, but also fish and squids and estimate their abundance.
Keywords: Animal Distribution Bio-logger Bio-logging Drones & Cap'
Programme: 1201
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Nicolas J., Verdun J., Baltzer A., Boy JP., Lemoine JP., Perosanz F., Tafflet A., . (2023). SIGNEAU : Signatures climatiques des surcharges hydrologiques observées par géodésie spatiale.
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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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Guilhermic C., Mouret A., Howa H., Pusceddu A., Baltzer A., Nardelli M.P. (2023). Effect of environmental gradients generated by tidewater glacier melting on sedimentary habitats and benthic meiofauna in Kongsfjorden (Svalbard): seasonal observations.
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Maria Jensen, Agnès Baltzer, Chol K., Forwick Matthias, John A. Howe, Katrine Husum. (2017). Land-fjord interaction and the impact os changing sedimentation rate on fjord environments – an integrated study of arctic sediment transport from land to see.
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Baltzer A., Bourriquen M., Fournier J., Mercier D., Costa S., Tolle F., Bernard E., Jensen M. (2017). Evolution of deltas and prodeltas of the south coast of Kongsfjorden (Svalbard) from 1995 to 2022.
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Tafflet A, Nicolas J., Boy JP., Lemoine JM., Peronzans F., Durand F., Gourillon L., Baltzer A., Verdun J. (2023). Ice melting impact on crustal deformation observed by space geodesy in Svalbard.
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Portier E., Mercier D., Decaulne A. (2023). Les glissements de terrain dans les Westfjords et les fjords de l'Est d'Islande : inventaire, morphométrie et variables explicatives.
Abstract: Les Westfjords et fjords de l’Est de l’Islande concentrent de nombreux glissements de terrain. Ces phénomènes visibles par observation à distance d’images satellites et d’un Modèle Numérique de Terrain (MNT) ont été inventoriés, puis mesurés et analysés. Au total, 251 et 290 glissements de terrain ont été recensés respectivement dans les Westfjords et les fjords de l’Est, au sein d’une base de données et dans un Système d’Informations Géographiques (SIG). Pour chaque glissement de terrain, sa localisation, sa morphométrie (longueur, largeur, superficie, épaisseur, volume estimé, …), ainsi que de potentielles variables de contrôle, notamment géologiques (lithologie, pendage), ou explicatives (orientation, âge de la déglaciation du versant affecté par le glissement de terrain) ont été relevées. Ces variables et la répartition des glissements ont été étudiées par analyse spatiale et statistique. Ce travail fournit un inventaire complémentaire des glissements de terrain pour ces deux secteurs. Cependant, les facteurs de déclenchement habituellement identifiés ne permettent pas une explication satisfaisante à leur répartition. Néanmoins, des pistes de réflexions se dessinent et l’élargissement de la base de données à l’échelle de l’Islande permet de les comparer d’un secteur à l’autre. Cette étude met en avant des foyers principaux de glissements de terrain : pour les Westfjords, une plus forte densité de glissements de terrain dans le nord-ouest de la zone étudiée et dans la partie la plus étroite de la péninsule ; et pour les fjords de l’Est, une plus forte densité dans le Nord de la zone étudiée. Ces foyers pourraient s’expliquer par les directions d’écoulement de la calotte glaciaire passée. D’autre part, un des constats est une surreprésentation des glissements orientés vers l’ouest et le sud pour les fjords de l’Est, et vers le sud et l’est pour les Westfjords. L’hypothèse proposée est un contrôle climatique : les versants davantage ensoleillés auraient subi une déglaciation plus rapide favorisant l’instabilité des versants. Les données recueillies suggèrent également que la lithologie (basaltes tertiaires) est une variable de contrôle et que la période pendant laquelle la zone de glissement de terrain est déglacée est une variable explicative de l'initiation du glissement de terrain. Les glissements de terrain observés s’inscriraient ainsi dans une dynamique paraglaciaire d’instabilité des versants après la phase de déglaciation
Keywords: Deglaciation Iceland Landslides Paraglacial
Programme: 1266
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