Nutrient dynamics under different ocean acidification scenarios in a low nutrient low chlorophyll system: The Northwestern Mediterranean Sea

J. Louis, Cecile Guieu, F. Gazeau

Research output: Contribution to journalArticle

Abstract

Two pelagic mesocosm experiments were conducted to study the impact of ocean acidification on Mediterranean plankton communities. A first experiment took place in summer 2012 in the Bay of Calvi (France) followed by an experiment in winter 2013 in the Bay of Villefranche (France) under pre-bloom conditions. Nine mesocosms were deployed: three served as controls and six were acidified in a targeted partial pressure of CO2 (pCO2) gradient from 450 to 1250 μatm. The evolution of dissolved organic and inorganic nutrient concentrations was observed using nanomolar techniques. The experiments were characterized by a large contribution of organic nutrients to nutrient pools and contrasting in situ conditions with an inorganic N/P ratio of 1.7 in summer and of 117 in winter. In the Bay of Calvi, initial conditions were representative of the summer oligotrophic Mediterranean Sea. While inorganic phosphate concentrations were depleted during both experiments, in situ inorganic nitrogen concentrations were higher in winter. However, nitrate was rapidly consumed in winter in all mesocosms during the acidification phase, leading to a decrease in N/P ratio to 13. During these first mesocosm experiments conducted in a low nutrient low chlorophyll area, nutrient dynamics were insensitive to CO2 enrichment, indicating that nutrient speciation and related biological processes were likely not impacted. During both experiments, nitrate and phosphate dynamics were controlled by the activity of small species that are favored in low nutrient conditions. In contrast to the theoretical knowledge, no increase in iron solubility at high pCO2 was observed.

Original languageEnglish (US)
Pages (from-to)30-44
Number of pages15
JournalEstuarine, Coastal and Shelf Science
Volume186
DOIs
StatePublished - Feb 15 2017

Fingerprint

nutrient dynamics
Mediterranean Sea
chlorophyll
nutrient
nutrients
winter
experiment
summer
mesocosm
France
nitrates
phosphates
nitrate
acidification
eutrophication
phosphate (inorganic)
plankton
solubility
nutrient content
inorganic nitrogen

Keywords

  • Iron
  • Mediterranean sea
  • Mesocosm experiments
  • Nitrogen
  • Nutrient dynamics
  • Ocean acidification
  • Oligotrophy
  • Phosphorus
  • Plankton community
  • Stoichiometry

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science

Cite this

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title = "Nutrient dynamics under different ocean acidification scenarios in a low nutrient low chlorophyll system: The Northwestern Mediterranean Sea",
abstract = "Two pelagic mesocosm experiments were conducted to study the impact of ocean acidification on Mediterranean plankton communities. A first experiment took place in summer 2012 in the Bay of Calvi (France) followed by an experiment in winter 2013 in the Bay of Villefranche (France) under pre-bloom conditions. Nine mesocosms were deployed: three served as controls and six were acidified in a targeted partial pressure of CO2 (pCO2) gradient from 450 to 1250 μatm. The evolution of dissolved organic and inorganic nutrient concentrations was observed using nanomolar techniques. The experiments were characterized by a large contribution of organic nutrients to nutrient pools and contrasting in situ conditions with an inorganic N/P ratio of 1.7 in summer and of 117 in winter. In the Bay of Calvi, initial conditions were representative of the summer oligotrophic Mediterranean Sea. While inorganic phosphate concentrations were depleted during both experiments, in situ inorganic nitrogen concentrations were higher in winter. However, nitrate was rapidly consumed in winter in all mesocosms during the acidification phase, leading to a decrease in N/P ratio to 13. During these first mesocosm experiments conducted in a low nutrient low chlorophyll area, nutrient dynamics were insensitive to CO2 enrichment, indicating that nutrient speciation and related biological processes were likely not impacted. During both experiments, nitrate and phosphate dynamics were controlled by the activity of small species that are favored in low nutrient conditions. In contrast to the theoretical knowledge, no increase in iron solubility at high pCO2 was observed.",
keywords = "Iron, Mediterranean sea, Mesocosm experiments, Nitrogen, Nutrient dynamics, Ocean acidification, Oligotrophy, Phosphorus, Plankton community, Stoichiometry",
author = "J. Louis and Cecile Guieu and F. Gazeau",
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TY - JOUR

T1 - Nutrient dynamics under different ocean acidification scenarios in a low nutrient low chlorophyll system

T2 - The Northwestern Mediterranean Sea

AU - Louis, J.

AU - Guieu, Cecile

AU - Gazeau, F.

PY - 2017/2/15

Y1 - 2017/2/15

N2 - Two pelagic mesocosm experiments were conducted to study the impact of ocean acidification on Mediterranean plankton communities. A first experiment took place in summer 2012 in the Bay of Calvi (France) followed by an experiment in winter 2013 in the Bay of Villefranche (France) under pre-bloom conditions. Nine mesocosms were deployed: three served as controls and six were acidified in a targeted partial pressure of CO2 (pCO2) gradient from 450 to 1250 μatm. The evolution of dissolved organic and inorganic nutrient concentrations was observed using nanomolar techniques. The experiments were characterized by a large contribution of organic nutrients to nutrient pools and contrasting in situ conditions with an inorganic N/P ratio of 1.7 in summer and of 117 in winter. In the Bay of Calvi, initial conditions were representative of the summer oligotrophic Mediterranean Sea. While inorganic phosphate concentrations were depleted during both experiments, in situ inorganic nitrogen concentrations were higher in winter. However, nitrate was rapidly consumed in winter in all mesocosms during the acidification phase, leading to a decrease in N/P ratio to 13. During these first mesocosm experiments conducted in a low nutrient low chlorophyll area, nutrient dynamics were insensitive to CO2 enrichment, indicating that nutrient speciation and related biological processes were likely not impacted. During both experiments, nitrate and phosphate dynamics were controlled by the activity of small species that are favored in low nutrient conditions. In contrast to the theoretical knowledge, no increase in iron solubility at high pCO2 was observed.

AB - Two pelagic mesocosm experiments were conducted to study the impact of ocean acidification on Mediterranean plankton communities. A first experiment took place in summer 2012 in the Bay of Calvi (France) followed by an experiment in winter 2013 in the Bay of Villefranche (France) under pre-bloom conditions. Nine mesocosms were deployed: three served as controls and six were acidified in a targeted partial pressure of CO2 (pCO2) gradient from 450 to 1250 μatm. The evolution of dissolved organic and inorganic nutrient concentrations was observed using nanomolar techniques. The experiments were characterized by a large contribution of organic nutrients to nutrient pools and contrasting in situ conditions with an inorganic N/P ratio of 1.7 in summer and of 117 in winter. In the Bay of Calvi, initial conditions were representative of the summer oligotrophic Mediterranean Sea. While inorganic phosphate concentrations were depleted during both experiments, in situ inorganic nitrogen concentrations were higher in winter. However, nitrate was rapidly consumed in winter in all mesocosms during the acidification phase, leading to a decrease in N/P ratio to 13. During these first mesocosm experiments conducted in a low nutrient low chlorophyll area, nutrient dynamics were insensitive to CO2 enrichment, indicating that nutrient speciation and related biological processes were likely not impacted. During both experiments, nitrate and phosphate dynamics were controlled by the activity of small species that are favored in low nutrient conditions. In contrast to the theoretical knowledge, no increase in iron solubility at high pCO2 was observed.

KW - Iron

KW - Mediterranean sea

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KW - Stoichiometry

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