Publication Date:
2024-03-15
Description:
Increases of atmospheric CO2 concentrations due to human activity and associated effects on aquatic ecosystems are recognized as an environmental issue at a global scale. Growing attention is being paid to CO2 enrichment effects under multiple stresses or fluctuating environmental conditions in order to extrapolate from laboratory-scale experiments to natural systems. We carried out a mesocosm experiment in coastal water with an assemblage of three model phytoplankton species and their associated bacteria under the influence of elevated CO2 concentrations. Net community production and the metabolic characteristics of the phytoplankton and bacteria were monitored to elucidate how these organisms responded to CO2 enrichment during the course of the algal bloom. We found that CO2 enrichment (1000 μatm) significantly enhanced gross primary production and the ratio of photosynthesis to chlorophyll a by approximately 38% and 39%, respectively, during the early stationary phase of the algal bloom. Although there were few effects on bulk bacterial production, a significant decrease of bulk bacterial respiration (up to 31%) at elevated CO2 resulted in an increase of bacterial growth efficiency. The implication is that an elevation of CO2 concentrations leads to a reduction of bacterial carbon demand and enhances carbon transfer efficiency through the microbial loop, with a greater proportion of fixed carbon being allocated to bacterial biomass and less being lost as CO2. The contemporaneous responses of phytoplankton and bacterial metabolism to CO2 enrichment increased net community production by about 45%, an increase that would have profound implications for the carbon cycle in coastal marine ecosystems.
Keywords:
Alkalinity, total; Aragonite saturation state; Bacteria, carbon demand; Bacteria, carbon demand, standard deviation; Bacteria, growth efficiency; Bacteria, growth efficiency, standard deviation; Bacteria, heterotrophic; Bacteria, heterotrophic, standard deviation; Bacterial production; Bacterial production, standard deviation; Bicarbonate ion; Biomass/Abundance/Elemental composition; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chlorophyll a; Chlorophyll a, standard deviation; Coast and continental shelf; Day of experiment; Entire community; EXP; Experiment; Field experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gross primary production, carbon dioxide; Gross primary production, carbon dioxide, standard deviation; Light-saturated productivity index, standard deviation; Light-saturated productivity index (carbon/chlorophyll a); Mesocosm or benthocosm; Net community production, carbon dioxide; Net community production, carbon dioxide, standard deviation; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Other metabolic rates; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Primary production/Photosynthesis; Respiration; Respiration rate, carbon dioxide; Respiration rate, carbon dioxide, standard deviation; Salinity; Silicate; Temperate; Temperature, water; Treatment; Type; Wuyuan_Bay
Type:
Dataset
Format:
text/tab-separated-values, 1478 data points
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