1. Nutrient Patchiness, Phytoplankton Surge-Uptake, and Turbulent History: A Theoretical Approach and Its Experimental Validation
- Author
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Laurent Seuront, Mathilde Schapira, Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), and Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS)
- Subjects
0106 biological sciences ,chemistry.chemical_element ,Context (language use) ,lcsh:Thermodynamics ,Atmospheric sciences ,nutrient patchiness ,01 natural sciences ,Zooplankton ,03 medical and health sciences ,chemistry.chemical_compound ,Nutrient ,lcsh:QC310.15-319 ,surge uptake ,Phytoplankton ,Ammonium ,14. Life underwater ,turbulent history ,[SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography ,030304 developmental biology ,lcsh:QC120-168.85 ,Fluid Flow and Transfer Processes ,0303 health sciences ,Turbulence ,[SDE.IE]Environmental Sciences/Environmental Engineering ,010604 marine biology & hydrobiology ,Mechanical Engineering ,fungi ,turbulence ,nutrient depletion ,Condensed Matter Physics ,Nitrogen ,6. Clean water ,Oceanography ,chemistry ,13. Climate action ,Turbulence kinetic energy ,[SDE]Environmental Sciences ,phytoplankton ,Environmental science ,lcsh:Descriptive and experimental mechanics - Abstract
Despite ample evidence of micro- and small-scale (i.e., millimeter- to meter-scale) phytoplankton and zooplankton patchiness in the ocean, direct observations of nutrient distributions and the ecological importance of this phenomenon are still relatively scarce. In this context, we first describe a simple procedure to continuously sample nutrients in surface waters, and subsequently provide evidence of the existence of microscale distribution of ammonium in the ocean. We further show that ammonium is never homogeneously distributed, even under very high conditions of turbulence. Instead, turbulence intensity appears to control nutrient patchiness, with a more homogeneous or a more heterogeneous distribution observed under high and low turbulence intensities, respectively, under the same concentration in nutrient. Based on a modelling procedure taking into account the stochastic properties of intermittent nutrient distributions and observations carried out on natural phytoplankton communities, we introduce and verify the hypothesis that under nutrient limitation, the &ldquo, turbulent history&rdquo, of phytoplankton cells, i.e., the turbulent conditions they experienced in their natural environments, conditions their efficiency to uptake ephemeral inorganic nitrogen patches of different concentrations. Specifically, phytoplankton cells exposed to high turbulence intensities (i.e., more homogeneous nutrient distribution) were more efficient to uptake high concentration nitrogen pulses (2 µ, M). In contrast, under low turbulence conditions (i.e., more heterogeneous nutrient distribution), uptake rates were higher for low concentration nitrogen pulses (0.5 µ, M). These results suggest that under nutrient limitation, natural phytoplankton populations respond to high turbulence intensities through a decrease in affinity for nutrients and an increase in their transport rate, and vice versa.
- Published
- 2020