Publication Date:
2024-03-15
Description:
Under ocean acidification (OA), the 200 % increase in CO2(aq) and the reduction of pH by 0.3-0.4 units are predicted to affect the carbon physiology and growth of macroalgae. Here we examined how the physiology of the giant kelp Macrocystis pyrifera is affected by elevated pCO2/low pH. Growth and photosynthetic rates, external and internal carbonic anhydrase (CA) activity, HCO3 (-) versus CO2 use were determined over a 7-day incubation at ambient pCO2 400 µatm/pH 8.00 and a future OA treatment of pCO2 1200 µatm/pH 7.59. Neither the photosynthetic nor growth rates were changed by elevated CO2 supply in the OA treatment. These results were explained by the greater use of HCO3 (-) compared to CO2 as an inorganic carbon (Ci) source to support photosynthesis. Macrocystis is a mixed HCO3 (-) and CO2 user that exhibits two effective mechanisms for HCO3 (-) utilization; as predicted for species that possess carbon-concentrating mechanisms (CCMs), photosynthesis was not substantially affected by elevated pCO2. The internal CA activity was also unaffected by OA, and it remained high and active throughout the experiment; this suggests that HCO3 (-) uptake via an anion exchange protein was not affected by OA. Our results suggest that photosynthetic Ci uptake and growth of Macrocystis will not be affected by elevated pCO2/low pH predicted for the future, but the combined effects with other environmental factors like temperature and nutrient availability could change the physiological response of Macrocystis to OA. Therefore, further studies will be important to elucidate how this species might respond to the global environmental change predicted for the ocean.
Keywords:
Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Aramoana; Benthos; Bicarbonate ion; Bicarbonate ion, standard deviation; Bicarbonate uptake rate; Bicarbonate uptake rate, standard error; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Calculated using SWCO2 (Hunter, 2007); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbon, total; Carbon, total, standard deviation; Carbon/Nitrogen ratio; Carbon/Nitrogen ratio, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard deviation; Carbon dioxide uptake, standard error; Carbon dioxide uptake rate; Carbonic anhydrase activity; Carbonic anhydrase activity, standard error; Change; Change, standard error; Chromista; Coast and continental shelf; Coulometric titration; EXP; Experiment; Figure; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Growth rate, standard error; Inhibition of net photosynthesis; Inhibition of net photosynthesis, standard error; Laboratory experiment; Macroalgae; Macrocystis pyrifera; Net photosynthesis rate, oxygen; Net photosynthesis rate, oxygen, standard error; Nitrogen, standard deviation; Nitrogen, total; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Other metabolic rates; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard error; Potentiometric titration; Primary production/Photosynthesis; Salinity; Single species; South Pacific; Species; Spectrophotometric; Table; Temperate; Temperature, water; Time in days; Treatment; δ13C; δ13C, standard deviation; δ15N; δ15N, standard deviation
Type:
Dataset
Format:
text/tab-separated-values, 766 data points
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