氮磷比率对3种典型赤潮藻生长的影响

EFFECTS OF DIFFERENT N:P RATIOS ON THE GROWTH OF PSEUDO-NITZSCHIA PUNGENS,PROROCENTRUM DONGHAIENSE AND PHAEOCYSTIS GLOBOSA

采用实验室内一次性培养的方法,在贫磷和富磷条件下分别测定了不同氮磷比率对3种典型赤潮藻东海原甲藻、球形棕囊藻和尖刺拟菱形藻生长的影响。结果表明,这3种藻的最适氮磷比率分别为30∶1、30∶1和10∶1。当N∶P比率介于0—100∶1之间时,3种赤潮藻的生长速率与营养盐浓度的关联度大于氮磷比率。东海原甲藻和球形棕囊藻对营养盐的需求量相对较高,在贫磷条件下的生长速率显著低于富磷条件;尖刺拟菱形藻对营养盐的需求量明显较低,在贫磷条件下可保持较高的生长速率。

In natural waters,the growth of phytoplankton was mainly affected by nitrogen, phosphorus and N： P ratios. In this paper, three representative HAB algae isolated from the coastal waters of China,Prorocentrum donghaiense,Phaeocystis globosa and Pseudo-nitzschia pungens were chosen for the research. Effects of different N： P ratios on the growth of these al- gae were tested in laboratory. This culture was grown in f/2 media at ca. 24℃ with salinity of ca. 30, light intensity of ca. 120μE/m2 · s, and light-dark cycle of 12： 12. Nitrogen- and phosphorous-starved cells of the species were obtained by growing the cells in f/2 media without addition of nitrogen and phosphorous until the ambient nitrogen or phosphorous had been depleted for 3 days. Such cells were used to test different N： P ratios on the growth rate of three HAB algae under two conditions of low-phosphorus （0. 362 μmol/L PO] -P） and high-phosphorus （36.2μmol/L PO4^3-P） ,the N： P ratios of 0,5：1,10：1,15：1,20： 1,25： 1,30： 1,50：1 and 100：1 were adopted,respectively. The results showed that the optimum N： P ratios of P. donghaiense,P, globosa and P. pungens were 30： 1,30： 1 and 10：1 respectively. While N： P ratios below 100：1 ,the relevancy between growth rate of the algae and nutrients concentration was more significant than that between growth rate and N： P ratios. P. donghaiense and P. globosa required high concentrations of nutrients, and growth rates in low-phosphorus conditions were much less than that in high-phosphorus waters;compared with two algae above mentioned, P. pungens demanded less nutrients, and maintained high growth rate under low-phosphorus conditions.