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Spatial and temporal variability in nutrients and carbon uptake during 2004 and 2005 in the eastern equatorial Pacific Ocean

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Abstract

The eastern equatorial Pacific plays a great role in the global carbon budget due to its enhanced biological productivity linked to the equatorial upwelling. However, as confirmed by the Equatorial Biocomplexity cruises in 2004 and 2005, nutrient upwelling supply varies strongly, partly due to the tropical instability waves (TIWs). The aim of this study was to examine patterns of spatial and temporal variability in the biological uptake of NO3, Si(OH)(4) and carbon in this region, and to evaluate the role of biological and physical interactions controlling this variability over seasonal and intraseasonal time scales. Here, high resolution Pacific ROMS-CoSiNE (Regional Ocean Modeling System-Carbon, Silicon, Nitrogen Ecosystem) model results were evaluated with in situ and remote sensing data. The results of model-data comparison revealed a good agreement in domain-average hydrographic and biological rate estimates, and patterns of spatio-temporal variability in primary productivity. We confirmed that TIWs have the potential to enhance phytoplankton biomass through an increased supply of nutrients and elevated local and instantaneous phytoplankton nutrient uptake as opposed to only advecting biomass. Furthermore, we concluded that initial biological conditions (e. g., zooplankton biomass) may play an important additional constraint on biological responses, in particular of large phytoplankton such as diatoms, to TIW-induced perturbations in the physical and biogeochemical fields and fluxes. In order to fully resolve the complexity of biological and physical interactions in the eastern equatorial Pacific, we recommended improving CoSiNE and other models by introducing more phytoplankton groups, variable Redfield and carbon to chlorophyll ratios, as well as resolving the Fe-Si co-limitation of phytoplankton growth.

Pacific Ocean Pacific Ocean biological productivity equatorial biocomplexity global carbon budget nutrient uptake nutrient variability seasonal change Animalia (Animals) - Animalia [33000] zooplankton common Plantae (Algae Microorganisms Nonvascular Plants Plants) - Algae [13000] phytoplankton common carbon 7440-44-0 chlorophyll iron 7439-89-6 nitrite 14797-65-0 silicic acid 10193-36-9 silicon 7440-21-3 04500 Mathematical biology and statistical methods 07504 Ecology: environmental biology - Bioclimatology and biometeorology 07506 Ecology: environmental biology - Plant 07508 Ecology: environmental biology - Animal 07512 Ecology: environmental biology - Oceanography 10060 Biochemistry studies - General 10064 Biochemistry studies - Proteins peptides and amino acids 10069 Biochemistry studies - Minerals 10515 Biophysics - Biocybernetics Computational Biology Ecology Environmental Sciences Environmental Sciences remote sensing applied and field techniques ROMS-CoSiNE model mathematical and computer techniques Climatology Marine Ecology Models and Simulations