Publication Date:
2024-03-15
Description:
A mesocosm experiment was conducted to evaluate the effects of future climate conditions on photosynthesis and productivity of coastal phytoplankton. Natural phytoplankton assemblages were incubated in field mesocosms under the ambient condition (present condition: ca. 400 ppmv CO2 and ambient temp.), and two future climate conditions (acidification condition: ca. 900 ppmv CO2 and ambient temp.; greenhouse condition: ca. 900 ppmv CO2 and 3 °C warmer than ambient). Photosynthetic parameters of steady-state light responses curves (LCs; measured by PAM fluorometer) and photosynthesis-irradiance curves (P-I curves; estimated by in situ incorporation of 14C) were compared to three conditions during the experiment period. Under acidification, electron transport efficiency (alpha LC) and photosynthetic 14C assimilation efficiency (alpha) were 10% higher than those of the present condition, but maximum rates of relative electron transport (rETRm,LC) and photosynthetic 14C assimilation (PBmax) were lower than the present condition by about 19% and 7%, respectively. In addition, rETRm,LC and alpha LC were not significantly different between and greenhouse conditions, but PBmax and alpha of greenhouse conditions were higher than those of the present condition by about 9% and 30%, respectively. In particular, the greenhouse condition has drastically higher PBmax and alpha than the present condition more than 60% during the post-bloom period. According to these results, two future ocean conditions have major positive effects on the photosynthesis in terms of energy utilization efficiency for organic carbon fixation through the inorganic carbon assimilation. Despite phytoplankton taking an advantage on photosynthesis, primary production of phytoplankton was not stimulated by future conditions. In particular, biomass of phytoplankton was depressed under both acidification and greenhouse conditions after the the pre-bloom period, and more research is required to suggest that some factors such as grazing activity could be important for regulating phytoplankton bloom in the future ocean.
Keywords:
Alkalinity, total; Aragonite saturation state; Bicarbonate ion; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell density; Chlorophyll a; Coast and continental shelf; Date; Effective quantum yield; Electron transport rate, relative; Electron transport rate efficiency; Entire community; EXP; Experiment; Field experiment; Figure; Fluorometric; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Geoje_Island; Grazing rate; Grazing rate, standard deviation; Gross community production of carbon dioxide; Gross community production of carbon dioxide, cumulative; Gross community production of carbon dioxide, per chlorophyll a; Gross photosynthesis rate, carbon dioxide, per chlorophyll a; Growth/Morphology; Identification; Incubation duration; Irradiance; Maximal electron transport rate, relative; Maximum potential capacity of photosynthesis; Mesocosm or benthocosm; Nitrate and Nitrite; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Photosynthetic efficiency, carbon production; Primary production/Photosynthesis; Salinity; Saturation light intensity; Silicate; Species; Table; Temperate; Temperature; Temperature, water; Time of day; Treatment
Type:
Dataset
Format:
text/tab-separated-values, 45219 data points
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