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

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,4 d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3.3×104 cells 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 1.02×10^7 cells L^-1, buf that of control was 1.7× 10^7 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 × 10^4 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 ofA. tamarense might be one of the causes that suppresses the growth ofP. donghaiense.