Modeling plankton ecosystem functioning and nitrogen fluxes in the oligotrophic waters of the Beaufort Sea, Arctic Ocean: a focus on light-driven processesReportar como inadecuado




Modeling plankton ecosystem functioning and nitrogen fluxes in the oligotrophic waters of the Beaufort Sea, Arctic Ocean: a focus on light-driven processes - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

1 LIENSs - LIttoral ENvironnement et Sociétés - UMR 7266 2 MIO - Institut méditerranéen d-océanologie 3 ISMER - Institut des Sciences de la MER de Rimouski 4 CHIMIE MIO - Institut méditerranéen d-océanologie 5 LOOB - Laboratoire Océanographique de Banyuls sur Mer 6 LOV - Laboratoire d-océanographie de Villefranche

Abstract : The Arctic Ocean AO undergoes profound changes of its physical and biotic environments due to climate change. In some areas of the Beaufort Sea, the stronger haline stratification observed in summer alters the plankton ecosystem structure, functioning and productivity, promoting oligotrophy. A one-dimension 1-D physical–biological coupled model based on the large multiparametric database of the Malina project in the Beaufort Sea was used i to infer the plankton ecosystem functioning and related nitrogen fluxes and ii to assess the model sensitivity to key light-driven processes involved in nutrient recycling and phytoplankton growth. The coupled model suggested that ammonium photochemically produced from photosensitive dissolved organic nitrogen i.e., photoammonification process was a necessary nitrogen source to achieve the observed levels of microbial biomass and production. Photoammonification directly and indirectly by stimulating the microbial food web activity contributed to 70% and 18.5% of the 0–10 m and whole water column, respectively, simulated primary production respectively 66% and 16% for the bacterial production. The model also suggested that variable carbon to chlorophyll ratios were required to simulate the observed herbivorous versus microbial food web competition and realistic nitrogen fluxes in the Beaufort Sea oligotrophic waters. In face of accelerating Arctic warming, more attention should be paid in the future to the mechanistic processes involved in food webs and functional group competition, nutrient recycling and primary production in poorly productive waters of the AO, as they are expected to expand rapidly.





Autor: Vincent Le Fouest - Bruno Zakardjian - Huixiang Xie - Patrick Raimbault - Fabien Joux - Marcel Babin -

Fuente: https://hal.archives-ouvertes.fr/



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