TY  - STD
AU  - Maria Pia Nardelli, Corentin Guilhermic
PY  - 2022//
TI  - Seasonal and interannual variability of benthic foraminiferal faunas under the influence of a tidal glacier
N2  - 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.
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ID  - MariaPiaNardelli2022
ER  -