营养盐对长江口2种主要赤潮原因藻光合色素和光合作用影响的比较研究

Comparative Research on the Effects of Different Nutrient Concentrations on the Photopigment Content and Photosynthesis of Two Bloom-forming Species Isolated from the Changjiang River Estuary

比较研究了不同营养条件对中肋骨条藻和东海原甲藻的光合色素含量和光合作用的影响.结果发现:①低浓度营养盐处理组培养的中肋骨条藻和东海原甲藻的叶绿素a(chlorophyll a,Chl-a)、叶绿素c(chlorophyll c,Chl-c)和总类胡萝卜素(totalcoloured carotenoids,TCC)含量均低于高浓度营养盐处理组;②初始N/P比值一定(16/1)的条件下,2种藻的光合速率变化不同,对于中肋骨条藻,低浓度处理组以单位细胞表示的光合速率从第5 d开始显著低于高浓度处理组,至试验结束时,2组的光合速率(以O2计,下同)分别为0.031×10-4μmol.(cell.h)-1和0.13×10-4μmol.(cell.h)-1,以单位叶绿素a(μg)表示的光合速率与高浓度处理组之间差异不显著,分别为12.92μmol.(μg.h)-1和13.03μmol.(μg.h)-1,而对于东海原甲藻,低浓度处理组的以单位细胞和单位叶绿素a表示的光合速率均显著高于高浓度处理组;P源充足低N处理组的2种藻的单位细胞表示和以单位叶绿素a表示的光合速率均高于高N处理组;N源充足低P处理组的2种藻以单位细胞表示和以单位叶绿素a表示的光合速率低于高P处理组;2种藻的光合速率与胞内磷酸盐浓度之间存在显著正相关关系;③相同营养条件下东海原甲藻比中肋骨条藻含有更多的单位细胞光合色素含量和更高的光合速率.试验从2种藻的光合特性角度,进一步论证了东海原甲藻比中肋骨条藻更能适应营养盐浓度较低的环境.

The contents of cellular chlorophyll a （Chl-a）, chlorophyll c （Chl-c）, total coloured carotenoids （TCC） and the photosynthesis of Skeletonema costatum and Prorocentrum donghaiense under different nutrient conditions were studied. The results showed that both species in the low nutrient concentration conditions had lower cellular Chl-a, Chl-c and TCC content than those in the high nutrient concentration conditions. When the initial N/P ratio was 16/1 while the concentrations were different, the two species had different photosynthetic rate responses. For S. costatum, the photosynthetic rate normalized by cell in the low nutrient concentration group （64 μmol/L N and 4 μmol/L P） was significantly lower than that in the high concentration group （256 μmol/L N and 16 μmol/L P） from the fifth day, and at the end of the experiment （ on the seventh day）, the photosynthetic rate was 0.031 x 10- 4 μmol· （ cell· h） - 1 and 0.13 ~ 10 - 4 μmol· （ cell· h） h） -1 respectively, while the photosynthetic rate normalized by Chl-a was 12.92μmol· （μg· h） -1 and 13.03 μmol· （μg· h） -1 for the two groups respectively, and there was no significant difference between them; however, for P. donghaiense, the photosynthetic rates normalized by both cell and Chl-a in the low concentration conditions （64 μmol/L N and 4 μmol/L P） were significantly higher than those in the high concentration conditions （256 μmol/L N and 16 μmol/L P）. For the two species, when P was sufficient, the low N concentration group （64 μmol/L N and 36 μmol/L P） and when N was sufficient, the low P concentration group （883μmol/L N and 4μmol/L P） had higher photosynthetic rates normalized by both cell and Chl-a than the high N concentration group （256μmol/L N and 36 μmol/L P） and the high P concentration group （883 μmol/L N and 16μmol/L P） respectively. There was a significant positive relationship between the photosynthetic rate and the intracellular P for both species, and P. donghaiense had higher cellular photopigment contents and photosynthetic rates than S. costatum under the same nutrient conditions. It could be inferred from their photosynthetic characteristics that P. donghaiense would survive better in low nutrient conditions compared with S. costatum.