摘要
The physiological responses of Nitzschia palea Kvtzing, a freshwater diatom, to elevated CO2 were investigated and compared with those of a marine diatom, Chaetoceros muelleri Lemmermann previously reported. Elevated CO2 concentration to 700 μl/L increased the dissolved inorganic carbon （D!C） and lowered the pH in the cultures of N. palea, thus enhancing the growth by 4%-20% during the whole growth period. High CO2-grown N. palea cells showed lower levels of dark respiration rates and higher Ik values. Light-saturated photosynthetic rates and photosynthetic efficiencies decreased in N. palea with the doubling CO2 concentration in airflow to the bottom of cultures, although the doubling CO2 concentration in airflow to the surface cultures had few effects on these two photosynthetic parameters. N. palea cells were found to be capable of using HCO5 in addition to gaseous CO2, and the CO2 enrichment decreased their affinity for HCO5 and CO2. Although doubled CO2 level would enhance the biomass of N. patea and C. muelleri to different extents, compared with the marine diatom, it had a significant effect on the specific growth rates of N. palea. In addition, the responses of photosynthetic parameters of IV. palea to doubled CO2 concentration were almost opposite to those of C. muelleri.
The physiological responses of Nitzschia palea Kützing,a freshwater diatom,to elevated CO2 were investigated and compared with those of a marine diatom,Chaetoceros muelleri Lemmermann previously reported.Elevated CO_2 concentration to 700μl/L increased the dissolved inorganic carbon (DIC) and lowered the pH in the cultures of N.palea,thus enhancing the growth by 4%-20% during the whole growth period.High CO2-grown N.palea cells showed lower levels of dark respiration rates and higher I_k values.Light-saturated photosynthetic rates and photosynthetic efficiencies decreased in N. palea with the doubling CO_2 concentration in airflow to the bottom of cultures,although the doubling CO_2 concentration in airflow to the surface cultures had few effects on these two photosynthetic parameters.N.palea cells were found to be capable of using HCO_3^-in addition to gaseous CO_2,and the CO_2 enrichment decreased their affinity for HCO_3^-and CO_2.Although doubled CO_2 level would enhance the biomass of N.palea and C.muelleri to different extents,compared with the marine diatom,it had a significant effect on the specific growth rates of N.palea.In addition,the responses of photosynthetic parameters of N.palea to doubled CO:concentration were almost opposite to those of C.muelleri.
基金
Supported by the National Natural Science Foundation of China (No.90411018,30270036) and by the Chinese Academy of Sciences
