Publication Date:
2024-03-15
Description:
Coccolithophores play an important role in organic matter export due to their production of the mineral calcite that can act as ballast. Recent studies indicated that calcification in coccolithophores may be affected by changes in seawater carbonate chemistry. We investigated the influence of CO2 on the aggregation and sinking behaviour of the coccolithophore Emiliania huxleyi (PML B92/11) during a laboratory experiment. The coccolithophores were grown under low (~180 µatm), medium (~380 µatm), and high (~750 µatm) CO2 conditions. Aggregation of the cells was promoted using roller tables. Size and settling velocity of aggregates were determined during the incubation using video image analysis. Our results indicate that aggregate properties are sensitive to changes in the degree of ballasting, as evoked by ocean acidification. Average sinking velocity was highest for low CO2 aggregates (~1292 m d-1) that also had the highest particulate inorganic to particulate organic carbon (PIC/POC) ratio. Lowest PIC/POC ratios and lowest sinking velocity (~366 m d-1) at comparable sizes were observed for aggregates of the high CO2 treatment. Aggregates of the high CO2 treatment showed a 4-fold lower excess density (~4.2*10**-4 g cm**-3) when compared to aggregates from the medium and low CO2 treatments (~1.7 g*10**-3 cm**-3). We also observed that more aggregates formed in the high CO2 treatment, and that those aggregates contained more bacteria than aggregates in the medium and low CO2 treatment. If applicable to the future ocean, our findings suggest that a CO2 induced reduction of the calcite content of aggregates could weaken the deep export of organic matter in the ocean, particularly in areas dominated by coccolithophores.
Keywords:
Alkalinity, Gran titration (Gran, 1950); Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Bacteria; Bacteria, abundance, standard deviation; Bacteria, dry mass; Bacteria, dry mass, standard deviation; Bicarbonate ion; Biomass/Abundance/Elemental composition; Calcite saturation state; Calcite saturation state, standard deviation; Calculated; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, particulate; Carbon, inorganic, particulate, standard deviation; Carbon, organic, particulate; Carbon, organic, particulate, standard deviation; Carbon, total, particulate; Carbon, total, particulate, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, partial pressure, standard deviation; Cells equivalent spherical diameter; Cells equivalent spherical diameter, standard deviation; Chromista; Conductivity and pH meter, pH/Cond 340i (WTW, Weilheim); Conductivity meter (WTW, Weilheim, Gemany); Containers and aquaria (20-1000 L or 〈 1 m**2); DATE/TIME; Density; Density, standard deviation; Element analyser CNS, EURO EA; Emiliania huxleyi; EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; Experimental treatment; Experiment day; FACSCalibur flow-cytometer (Becton Dickinson); Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Haptophyta; Laboratory experiment; Laboratory strains; Light:Dark cycle; Nitrogen, total, particulate; Nitrogen, total, standard deviation; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Particles, volume concentration; Particles, volume concentration, standard deviation; Particulate inorganic carbon/particulate organic carbon ratio; Particulate inorganic carbon/particulate organic carbon ratio, standard deviation; Pelagos; pH; pH, standard deviation; Phytoplankton; Porosity; Porosity, standard deviation; Radiation, photosynthetically active; Salinity; see reference(s); Single species; Sinking velocity; Sinking velocity, standard deviation; Temperature, water
Type:
Dataset
Format:
text/tab-separated-values, 246 data points
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