Publication Date:
2024-03-15
Description:
To predict effects of climate change and possible feedbacks, it is crucial to understand the mechanisms behind CO2 responses of biogeochemically relevant phytoplankton species. Previous experiments on the abundant N2 fixers Trichodesmium demonstrated strong CO2 responses, which were attributed to an energy reallocation between its carbon (C) and nitrogen (N) acquisition. Pursuing this hypothesis, we manipulated the cellular energy budget by growing Trichodesmium erythraeum IMS101 under different CO2 partial pressure (pCO2) levels (180, 380, 980 and 1400?µatm) and N sources (N2 and NO3-). Subsequently, biomass production and the main energy-generating processes (photosynthesis and respiration) and energy-consuming processes (N2 fixation and C acquisition) were measured. While oxygen fluxes and chlorophyll fluorescence indicated that energy generation and its diurnal cycle was neither affected by pCO2 nor N source, cells differed in production rates and composition. Elevated pCO2 increased N2 fixation and organic C and N contents. The degree of stimulation was higher for nitrogenase activity than for cell contents, indicating a pCO2 effect on the transfer efficiency from N2 to biomass. pCO2-dependent changes in the diurnal cycle of N2 fixation correlated well with C affinities, confirming the interactions between N and C acquisition. Regarding effects of the N source, production rates were enhanced in NO3-grown cells, which we attribute to the higher N retention and lower ATP demand compared with N2 fixation. pCO2 effects on C affinity were less pronounced in NO3- users than N2 fixers. Our study illustrates the necessity to understand energy budgets and fluxes under different environmental conditions for explaining indirect effects of rising pCO2.
Keywords:
Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Bacteria; Bicarbonate ion; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, half saturation concentration; Carbon, inorganic, dissolved, half saturation concentration, standard deviation; Carbon, inorganic, dissolved, standard deviation; Carbon, organic, particulate, standard deviation; Carbon, organic, particulate/Nitrogen, organic, particulate ratio; Carbon, organic, particulate/Nitrogen, organic, particulate ratio, standard deviation; Carbon, organic, particulate per chlorophyll a; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coulometric titration; Cyanobacteria; Effective absorbance cross-section of photosystem II; Effective absorbance cross-section of photosystem II, standard deviation; Figure; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Growth rate, standard deviation; Identification; Irradiance; Laboratory experiment; Laboratory strains; Light:Dark cycle; Macro-nutrients; Maximum photochemical quantum yield of photosystem II; Maximum photochemical quantum yield of photosystem II, standard deviation; Net oxygen evolution, per chlorophyll a; Net oxygen evolution, per chlorophyll a, standard deviation; Nitrogen, organic, particulate, standard deviation; Nitrogen, organic, particulate per chlorophyll a; Nitrogen fixation rate per chlorophyll a; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Other metabolic rates; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Particulate organic carbon, production, standard deviation; Particulate organic carbon production, per chlorophyll a; Particulate organic nitrogen production, per chlorophyll a; Particulate organic nitrogen production, standard deviation; Pelagos; pH; pH, standard deviation; Phytoplankton; Potentiometric; Potentiometric titration; Primary production/Photosynthesis; Re-oxidation time of the Qa acceptor; Re-oxidation time of the Qa acceptor, standard deviation; Respiration; Salinity; Single species; Species; Temperature, water; Time in hours; Time point, descriptive; Treatment; Trichodesmium erythraeum
Type:
Dataset
Format:
text/tab-separated-values, 1523 data points
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