光合色素标记法测定不同类群浮游植物的光合速率和生长速率

Photopigment radiolabelling as a tool for determining group-specific phytoplankton photosynthesis rate and growth rate

尝试利用放射性同位素14C示踪方法测定浮游植物不同类群的光合速率和生长速率,并通过实验室和现场海域的培养实验来初步评估该技术的可行性.通过高效液相色谱法分离光合色素,手动收集并测定各对应光合色素峰的放射性活度,依据Redalje-Laws法并结合类胡萝卜素标记法计算出各大类群浮游植物的光合速率和生长速率.实验结果表明,在实验室纯种培养的4株藻光合速率范围为347.73~678.98 mg/（dm3.d）,最高的为绿藻的小球藻,最低的为定鞭金藻的球石藻.其生长速率范围为0.12~0.24 d-1,最高的为球石藻,最低的为小球藻.在现场海域各类群的光合速率相对较低,变化范围为0.63~68.78 mg/（dm3.d）,生长速率在0.07~1.68 d-1之间.本研究首次在我国海域通过现场原位测定得到不同类群浮游植物的光合速率和生长速率.但在测定过程中存在的样品含量和放射活度较低等问题还有待于进一步解决.

Radioactive isotope 14C was used to measure the group-specific carbon fixation rates and growth rates of phytoplankton and laboratory and field culture experiments were conducted to assess the feasibility of the technology.HPLC was used to separate the pigments and each component was then collected manually,then the correspon-ding photosynthetic pigment peak of radioactive activity by the liquid scintillation counter were determined.The Redalje-Laws and carotenoids radiolabelling method were applied to determine the phytoplankton photosynthesis rate and growth rate of each phytoplankton group.The results showed that,for the four species incubated in the laboratory,the carbon fixation rates ranged from 347.73～678.98 mg/（dm3·d）,with Chlorella sp.having the highest carbon fixation rates and Emiliania huxleyi having the lowest.The growth rates of the four species ranged from 0.12～0.24 d-1,the highest being that of Emiliania huxleyi and the lowest being that of Chlorella sp.Field experiments showed lower carbon fixation rates of phytoplankton groups,ranging from 0.63～68.78 mg/（dm3·d）.The growth rates ranged from 0.07～1.68 d-1 and changed with stations in the South China Sea.This is the first study to determine the group-specific phytoplankton photosynthesis rate and growth rate by the in situ measured method.There are still some problems associated with field application of this protocol,such as the low concentrations of the pigments and radiotracer samples.