氮磷比对浙江近岸浮游植物群落结构影响的实验研究

Microcosm experiments on the influence of different N/P ratios on phytoplankton community structure in the coast of Zhejiang Province

通过室内受控实验方法研究不同氮磷比(N/P)(1∶1,4∶1,8∶1,16∶1,32∶1,64∶1,128∶1和256∶1)对浙江近岸秋季浮游植物群落结构的影响。结果表明,不同N/P对浮游植物群落的多样性指数、物种组成及演替过程均有显著影响。实验前期(6～12d),低N/P组(1∶1)H′,Ma,J和Dr值均偏小,实验结束时(30d)8∶1和16∶1组H′,J和Dr值小于其他各组。实验初期(6d),高N/P组(128∶1和256∶1)对硅藻生长有明显促进作用,实验结束时8∶1和16∶1组更适合硅藻生长。此外,各组中浮游植物群落都呈硅藻→甲藻的基本演替规律,外界环境条件的改变较之群落初始物种组成对浮游植物群落的演替顺序更具决定性作用。

In order to better understand the effects of different nitrogen-phosphorus（N/P） ratios（1∶1,4∶1,8∶1,16∶1,32∶1,64∶1,128∶1 and 256∶1） on phytoplankton community structure,a microcosm experiment was conducted for 30 days during the autumn near Dongtou Island in the East China Sea.The results indicated that the diversity indices,species composition and community succession of the phytoplankton community varied significantly with the N/P ratios.The values of H′,Ma,J and Dr were lower in the low N/P ratio treatment（1∶1） during the early phase of culture（day 6 to 12）,while the values of H′,J and Dr were lower in the 8∶1 and 16∶1 treatments at the end of culture.On the other hand,a higher cell abundance of diatom was observed in the high N/P ratio treatments（128∶1 and 256∶1） on day 6 and in the 8∶1 and 16∶1 treatments on day 30.Moreover,a definite community succession order from diatoms to dinoflagellates was observed in all treatments which was in accordance with the result reported in other studies conducted in the East China Sea,therefore,we speculate that the order of phytoplankton succession cultured（enclosure or in-laboratory） was related to the changed environment factors rather than its initial composition.