浒苔和紫菜等2种海藻干体对3种赤潮微藻生长的抑制作用

Inhibition of Enteromorpha prolifera and Porphyra yazoensis powders on the Growth of three species of the red tide microalgae

在添加浒苔和紫菜干体的条件下,通过测定藻细胞数量,观察藻细胞形态,分析海藻干体对米氏凯伦藻、中肋骨条藻和塔玛亚历山大藻的半抑制和完全抑制浓度以及半抑制和完全抑制浓度有效作用的起始藻细胞数量范围,研究了浒苔和紫菜干体对3种赤潮微藻生长的影响。在此基础上,设定海藻干体的添加量为其完全抑制浓度,通过监测微藻培养液中总氮(硝酸态氮、氨态氮和亚硝酸态氮)和总磷等变化,分析海藻干体添加对培养液营养化程度的影响。结果表明:(1)当浒苔和紫菜干体浓度分别大于0.8g/L和1.0 g/L时,海藻干体能显著抑制3种赤潮微藻的生订,它们对赤潮微藻的生长抑制率超过60%(第12 d)。(2)浒苔和紫菜干体对3种实验微藻的半抑制浓度(IC_(50))接近,在0.71～1.22g/L之间;但完全抑制浓度(IC_(100))差别较大,浒苔干体对3种赤潮微藻的完全抑制浓度在2.4～2.8g/L范围,其数值约为紫菜干体对它们的完全抑制浓度的2倍。(3)3种赤潮微藻起始藻细胞数量不超过40×10~4·mL^(-1)(对于米氏凯伦藻和中肋骨条藻来说,起始藻细胞数量可增大至60×10~4·mL^(-1)),海藻干体对3种实验微藻的半抑制浓度和完全抑制浓度均有效。(4)添加海藻干体的实验组培养液中总氮和总磷含量均明显高于对照培养液中总氮和总磷含量。其中,实验组培养液中总氮浓度为382μg/L,总磷浓度明显低于100μg/L。综上所述,浒苔和紫菜干体具有强烈的抑藻作用,且不会造成培养液营养加剧现象,可尝试应用于赤潮微藻的控制与治理中。

To study the effects of Enteromorpha prolifera and Porphyra yazoensis powders on the growth of three species of the red tide microalgae （Karenia mikimitoi, Skeletonema costatum and A lexandrium tamarense） , the macroalgae powders were added to the microalgae culture medium, respectively. Based on the observation of algal morphology and the measurement of algal density, and the analysis of half inhibition concentration （IC50） and inhibition concentration （IC100）, and of initial algal cell number range with effective action of IC50 and IC100, the results showed the growth of those microalgae was significantly inhibited by E. prolifera and P. yazoensis powders at the concentration of 0.8 g/L and 1.0 g/L, respectively. And the inhibitory effect of all tested microalgae by macroalgae powders was above 60 % in day 12. IC50 of E. prolifera and P. yazoensis powders was equivalent, varying between 0.71 g/L and 1.22 g/L. ICi00 of two macroalgae powders was significantly different, and IC100 of E. prolifera changed between 2.4 g/L and 2.8 g/L, which was approximately 2 times of that of P. yazoensis powders. The ICso and IC100 were effective when initial cell number was less than 40×104 ·mL^-1, but its value could be increased to 60×10^4·mL^-l for K. mikimitoi and S. costatum. On this basis, macroalgae powders were at the lethal concentration which was added to the microalgae culture medium, and eutrophication effects of macroalgae powders added to the microalgae culture medium were analyzed by monitoring total nitrogen （nitrate, nitrite nitrogen and ammonia nitrogen） and total phosphorus in the microalgae culture medium. During the training period, total nitrogen and total phosphorus content in the culture medium of the experimental group which added maroalgae powders were significantly higher than that in controls. Total nitrogen concentration in the culture medium of the experimental group was 382 μg/L and total phosphorus concentration was lower than 100 μg/L. According to the above results, those macroalgae powders have strong inhibiting effect and could not cause microalgae culture medium enteromorpha. They could be used in the red tide control.