Effects of increase glacier discharge on phytoplankton bloom dynamics and pelagic geochemistry in a high Arctic fjord

• Published in: Progress in Oceanography
• Main Authors: Calleja, Maria Ll., Kerhervé, P., Bourgeois, S., Kędra, M., Leynaert, Aude, Devred, E., Babin, M., Morata, N.
• Other Authors: Instituto Andaluz de Ciencias de la Tierra (IACT), Consejo Superior de Investigaciones Científicas Madrid (CSIC)-Universidad de Granada (UGR), Red Sea Research Centre (RSRC), King Abdullah University of Science and Technology (KAUST), Centre de Formation et de Recherche sur les Environnements Méditérranéens (CEFREM), Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Aberdeen, Polish Academy of Sciences (PAN), Fisheries and Oceans Canada (DFO), Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval Québec (ULaval)-Centre National de la Recherche Scientifique (CNRS), ANR-11-PDOC-0018,ECOTAB,Effet des changements climatiques sur le benthos en Arctique(2011)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: Diatom bloom; Carbon and nitrogen stable isotopes; Organic matter; Glaciers; Arctic; Fjords; ACL; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDE.IE]Environmental Sciences/Environmental Engineering; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Svalbard; glacier; Global warming; Kongsfjord*; Kongsfjorden; Phytoplankton; Spitsbergen
• Online Access: https://hal-univ-perp.archives-ouvertes.fr/hal-01686759; https://hal-univ-perp.archives-ouvertes.fr/hal-01686759/document; https://hal-univ-perp.archives-ouvertes.fr/hal-01686759/file/Calleja_etal_PiO_2017.pdf; https://doi.org/10.1016/j.pocean.2017.07.005

International audience Arctic fjords experience extremely pronounced seasonal variability and spatial heterogeneity associated with changes in ice cover, glacial retreat and the intrusion of continental shelf’s adjacent water masses. Global warming intensifies natural environmental variability on these important systems, yet the regional and global effects of these processes are still poorly understood. In the present study, we examine seasonal and spatial variability in Kongsfjorden, on the western coast of Spitsbergen, Svalbard. We report hydrological, biological, and biogeochemical data collected during spring, summer, and fall 2012. Our results show a strong phytoplankton bloom with the highest chlorophyll a (Chla) levels ever reported in this area, peaking 15.5 μg/L during late May and completely dominated by large diatoms at the inner fjord, that may sustain both pelagic and benthic production under weakly stratified conditions at the glacier front. A progressively stronger stratification of the water column during summer and fall was shaped by the intrusion of warm Atlantic water (T >3 °C and Sal >34.65) into the fjord at around 100 m depth, and by turbid freshwater plumes (T <1 °C and Sal< 34.65) at the surface due to glacier meltwater input. Biopolymeric carbon fractions and isotopic signatures of the particulate organic material (POM) revealed very fresh and labile material produced during the spring bloom (13C enriched, with values up to −22.7‰ at the highest Chl a peak, and high in carbohydrates and proteins content – up to 167 and 148 μg/L, respectively-), and a clear and strong continental signature of the POM present during late summer and fall(13C depleted, with values averaging −26.5‰, and high in lipid content – up to 92 μg/L-) when freshwater melting is accentuated. Our data evidence the importance of combining both physical (i.e. water mass dominance) and geochemical (i.e. characteristics of material released by glacier runoff) data in order to understand the timing, intensity ...