1. Plankton ecosystem functioning and nitrogen fluxes in the most oligotrophic waters of the Beaufort Sea, Arctic Ocean: a modeling study.
- Author
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Le Fouest, V., Zakardjian, B., H. Xie, Raimbault, P., Joux, F., and Babin, M.
- Subjects
PLANKTON ,BIOTIC communities ,NITROGEN ,CLIMATE change ,MATHEMATICAL models - Abstract
The Arctic Ocean (AO) undergoes profound changes of its physical and biotic environments due to climate change. The greater light exposure and stratification alter its plankton ecosystem structure, functioning and productivity promoting oligotrophy in some areas as the Beaufort Sea. 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 functioning and nitrogen fluxes within the summer plankton ecosystem and (ii) to assess the model sensitivity to key light-associated 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. It contributed to ca. two-thirds and one-third of the simulated surface (0-10 m) and depth-integrated primary and bacterial production, respectively. The model also suggested that carbon to chlorophyll ratios for small (<5 µm) phytoplankton (ca. 15-45 gg
-1 ) lower than those commonly used in biogeochemical models applied to the AO 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 groups competition, nutrient recycling and primary production in poorly productive waters of the AO as they are expected to expand rapidly. [ABSTRACT FROM AUTHOR]- Published
- 2012
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