营养盐限制条件下塔玛亚历山大藻对东海原甲藻的化感作用研究

Allelopathic Effect of Alexandrium tamarense on Prorocentrum donghaiense under Limited Nutrient Conditions

摘要:

为明确塔玛亚历山大藻（Alexandrium tamarense）对东海原甲藻（Prorocentrum donghaiense）生长的化感作用，研究了在N、P限制及正常营养盐条件下（又称富营养）塔玛亚历山大藻无细胞滤液对东海原甲藻生长的影响，并探讨了3种不同营养盐条件下两种藻共培养时的生长状况。结果表明，半连续培养时，营养盐限制下，塔玛亚历山大藻无细胞滤液对东海原甲藻的生长均有一定影响。N限制下，5 d后东海原甲藻藻密度显著低于未加滤液的对照组，藻密度为1.02×10⁷ cells L^-1，对照组为1.7×10⁷ cells L^-1；P限制下，东海原甲藻藻密度与对照组差异不显著，5 d后藻密度为1.44×10⁷ cells L^-1；富营养条件下，东海原甲藻藻密度与对照组无明显区别。共培养时，塔玛亚历山大藻对东海原甲藻生长的抑制作用更为显著，N、P限制下，4d后东海原甲藻全部死亡，且聚集成团形成沉淀；富营养条件下，仍有少量东海原甲藻存活（藻密度3.3×10⁴cells L^-1）。这表明，塔玛亚历山大藻对东海原甲藻的生长有一定的化感作用。营养盐限制可促进塔玛亚历山大藻化感物质的合成和释放，化感作用是塔玛亚历山大藻抑制东海原甲藻生长的原因之一。

Abstract:

To investigate the potential allelopathic effect of Alexandrium tamarense on the growth of Prorocentrum donghaiense, experiments were designed to co-culture both algae or to culture P. donghaiense with cell-free filtrate from A. tamarense under N- and P-limited and nutrient-sufficient （normal） conditions. The results showed that the growth of P. donghaiense was inhibited when semi-continuously cultured in cell-free filtrate of A. tamarense. Under N-limited condition, cell density of P. donghaiense was significantly lower than the control （without addition of filtrate） after 5 days of culture, the cell density being 1.02×10⁷ cells L^-1, buf that of control was 1.7× 10⁷ cells L^-1. Under the P-limited condition, there was no obvious difference in cell density between treated alga and the control, the cell density of treated alga being 1.44× 10^7 cells L^-1. Under nutrient-sufficient condition, there was no difference in cell density between P. donghaiense and the control. In co-culture, the inhibitory effect ofA. tamarense on P. donghaiense was more obvious. Under N- and P-limitied conditions, P. donghaiense was entirely killed by A. tamarense after 4 days, the former gathered into groups and sank. However, a few P. donghaiense survived （cell density at 3.3 × 10⁴ cells L^-1） under nutrient-sufficient conditions. The results suggested that A. tamarense have allelopathic effect on P. donghaiense, and the production ofallelochemicals would be stimulated under N- and P-limited conditions. Thus, the inhibitory effect of A. tamarense might be one of the causes that suppresses the growth of P. donghaiense.