磷酸盐不同补充方式对塔玛亚历山大藻生长和产毒影响

Effects of Different Supplement Ways of Phosphate on the Growth and Toxins Production of Alexandrium tamarense

实验室条件下探讨经过磷酸盐限制后,2种不同补给方式对塔玛亚历山大藻生长和产毒的影响。结果表明,经磷限制后,在一次性添加和脉冲式添加2种磷酸盐补充方式下,塔玛亚力山大藻的最大比生长速率分别为0.71d-1和0.63d-1,明显高于在f/2培养液条件下的0.40d-1;同时,一次性添加组所达到的最大生物量明显高于脉冲式添加组(P<0.05),表明在寡磷酸盐海区,一旦磷酸盐得到丰富补充后,浮游植物会暴发性增长,极易引发赤潮。但是,2组在光能转化效率Fv/Fm值和毒素变化方面都没有表现出显著差异(P>0.05)。前6d受到磷酸盐限制的塔玛亚历山大藻,其光能转换效率值Fv/Fm从0.62降至0.40,单位细胞毒素含量却是在f/2培养液条件下的6倍;而添加磷酸盐后,Fv/Fm值在3d内迅速升至0.60,细胞数量呈现快速增长态势,单位细胞毒素含量却开始降低。至培养结束时,Fv/Fm值缓慢降低至0.40左右,单位细胞毒素含量分别为0.73和0.78pgSTXeq/个,与f/2培养液条件下的0.76pgSTXeq/个相当。HPLC测定结果表明,塔玛亚历山大藻南海株毒素含量主要是由GTX1,GTX4,neoSTX和C2四类组分构成,其和占总毒素含量的98%以上。

Effects of two different Alexandrium tamarense （isolated supplement ways of phosphate on the growth and toxins production of from South China Sea） were studied. The results show that the one-off supplement treatment and pulse supplement treatment may lead to a rising-up trend in cell growth and toxins production. After phosphate addition, the maximum specific growth rates （umax ） of two groups reach to 0.71 d-1 and 0.63 d-1 , respectively, which are remarkably higher than 0.40 d-1 of the control （f/2 medium）, and the one off phosphate supplement can result in more biomass than the pulse one （P〈0.05）. This indicates that if enough phosphate is added to the previous phosphate-inadequate area, an outbreak of red tide may easily be caused. However, there is no significant difference in both the photochemical efficiency Fv/Fm and the per cell toxicity between the two groups （P〉0. 05）. The Fv/Fm of Alexandrium tamarense goes from 0.6 at the initial phase down to 0.40 after the 6-day phosphate limitation, and the cell toxicity of the one-off supplement group and the pulse one is about 6 times of that of the control. After phosphate supplement, the Fv/Fm rises up to 0.60 again within 3 days, with the increasing of biomass and the decreasing of per cell toxicity. At the end of the culture the Fv/Fm decreases gradually to 0.40 and the per cell toxicity of two phosphate-limited groups decreases to 0.73 and 0.78 pgSTXeq/cell respectively, being close to the control （0. 76 pgSTXeq/cell）. The PSP toxins detection by HPLC has showed that GTX1, GTX4, neoSTX and C2 mainly constitute the total toxicity of Alexandrium tamarense, accounting for 98% .