Seawater carbonate chemistry and growth and particulate organic nitrogen production of diatom Thalassiosira pseudonana

Phytoplankton in the upper oceans are exposed to changing light levels due to mixing, diurnal solar cycles and weather conditions. Consequently, effects of ocean acidification are superimposed upon responses to variable light levels. We therefore grew a model diatom Thalassiosira pseudonana under ei...

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Bibliographic Details
Main Authors: Li, Wei, Wang, Tifeng, Campbell, Douglas A, Gao, Kunshan
Format: Dataset
Language:English
Published: PANGAEA 2020
Subjects:
Alkalinity
total
standard deviation
Aragonite saturation state
Bicarbonate ion
Biomass/Abundance/Elemental composition
Bottles or small containers/Aquaria (<20 L)
Calcite saturation state
Calculated using CO2SYS
Calculated using seacarb after Nisumaa et al. (2010)
Calculated using seacarb after Orr et al. (2018)
Carbon
inorganic
dissolved
organic
particulate
per cell
production per cell
Carbon/Nitrogen ratio
Carbonate ion
Carbonate system computation flag
Carbon dioxide
Ocean acidification
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.922459
https://doi.org/10.1594/PANGAEA.922459
Description
Summary:Phytoplankton in the upper oceans are exposed to changing light levels due to mixing, diurnal solar cycles and weather conditions. Consequently, effects of ocean acidification are superimposed upon responses to variable light levels. We therefore grew a model diatom Thalassiosira pseudonana under either constant or variable light but at the same daily photon dose, with current low (400 μatm, LC) and future high CO2 (1000 μatm, HC) treatments. Variable light, compared with the constant light regime, decreased the growth rate, Chl a, Chl c, and carotenoid contents under both LC and HC conditions. Cells grown under variable light appeared more tolerant of high light as indicated by higher maximum relative electron transport rate and saturation light. Light variation interacted with high CO2/lowered pH to decrease the carbon fixation rate, but increased particulate organic carbon (POC) and particularly nitrogen (PON) per cell, which drove a decrease in C/N ratio, reflecting changes in the efficiency of energy transfer from photo-chemistry to net biomass production. Our results imply that elevated pCO2 under varying light conditions can lead to less primary productivity but more PON per biomass of the diatom, which might improve the food quality of diatoms and thereby influence biogeochemical nitrogen cycles.

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