赤潮藻中肋骨条藻的光合作用对海水pH和N变化的响应  

RESPONSE OF PHOTOSYNTHESIS OF THE BLOOM-FORMING MARINE DIATOM SKELETONEMA COSTATUM TO CHANGES IN pH AND INORGANIC NITROGEN CONCENTRATIONS IN SEAWATER

作　　者：陈雄文[1] 高坤山[2] 

机构地区：[1]中国科学院水生生物研究所 [2]汕头大学海洋生物研究所,汕头515063

出　　处：《水生生物学报》2004年第6期635-639,共5页Acta Hydrobiologica Sinica

基　　金：家自然科学基金重点项目 (3 983 0 0 60 )资助

摘　　要：为探讨赤潮发生时中肋骨条藻 (Skeletonemacoatatum)的光合作用生理变化 ,研究了不同无机氮 (N)水平上 ,海水pH值升高对其胞外碳酸酐酶 (CA)和光合生理特性的影响。海水pH从 8.2升至 8.7时 ,中肋骨条藻胞外CA被诱导 ,细胞对无机碳的亲和力 (1/Km)提高 ;在pH8 7时 ,高N条件下的胞外CA活性是低N条件下的 3倍 ,1/Km 值也提高了 80 %。单位叶绿素a的最大净光合能力 (Pam)在不同pH和N水平上没有显著差异 ;但单位细胞的最大净光合能力 (Pcm)提高了 10 0 %。这些结果表明 ,赤潮发生时 ,中肋骨条藻通过启动无机碳浓缩机制 (CCM) ,提高细胞对无机碳利用效率 ,使其在低CO2 (高pH)环境下维持光合机构正常运行 ;充足的N源有利于提高CCM的效率 ,从而提高CO2 环境下的光合固碳能力。The bloom-forming marine diatom Skeletonema costatum (Greville)Cleve (strain No.2042)was cultured under different levels of pH and inorganic nitrogen(N)at 20℃ and 210 μmolm -2 s -1 (12:12/L:D)and its extracellular carbonic anhydrase(CA)and photosynthetic O 2 evolution were investigated in order to see its physiological response to changes in pH under high N(300 μmol/L)and low N(10μmol/L)levels during S.costatum bloom.The extracellular CA activity was assayed by the potentiometerical method,and the photosynthetic O 2 evolution was determined by a Clark-type Oxygen Electrode.When pH in seawater rose from 8 2 to 8.7,the extracellular CA activity was induced and photosynthetic CO 2 affinity(1/K m) increased,and,at pH8.7,the extracellular CA activity and photosynthetic CO 2 affinity at the high N level were 2-times and 80% higher than those at the low N level,respectively.The chla-specific light-saturated photosynthetic rates(P a m)were no significant differences under different pH and N levels,but the cell-specific light-saturated photosynthetic rates(P c m) was 100% higher at the high N level than at the low N level;By contrast,the cell-specific dark respiratory rates (R c d) were insignificant differences among the different pH and N levels,but the chla-specific dark respiratory rates (R c d) were l-fold higher at the low N level than at the high N level.The apparent photosynthetic efficiencies (α) were not significantly different for the alga grown among the different pH and N levels.The cellular chla content was l-fold higher at high-N-grown cells than at low-N-grown cells,but it was not affected by the pH changes.It was concluded that the alga increased the activities of extracellular CA and photosynthetic CO 2 affinity with the rise of pH in seawater (or the decrease of CO 2 in seawater),but their activites were higher at high N level than at low N level,suggesting that,during occurance of the bloom, S.costatum could develop the inorganic carbon concentration mechanism (C

关 键 词：中肋骨条藻 胞外碳酸酐酶 赤潮 光合作用 无机碳亲和力 海水 

分 类 号：Q949.2[生物学—植物学] X55[环境科学与工程—环境工程]