三嗪除草剂扑草净对海洋浮游植物群落的影响——基于对微藻种群动态、种间竞争和光合能力的分析

Effects of triazine herbicide prometryn on marine phytoplankton communities-Based on analysis of microalgae population dynamics,interspecific competition and photosynthetic capacity

以三角褐指藻(Phaeodactylum tricornutum)、海水小球藻(Chlorella pacifica)和球等鞭金藻(Isochrysis galbana)为研究对象,设置单藻培养组和双藻1:1(细胞密度比)共培养组,研究了扑草净对3种海洋饵料微藻种群动态、光合能力和种间竞争的影响.结果表明,扑草净对三角褐指藻、海水小球藻和球等鞭金藻的96h-EC50值分别为为7.65,16.67,4.11μg/L,扑草净对3种微藻的毒性大小为:球等鞭金藻>三角褐指藻>海水小球藻;扑草净通过抑制微藻的光合作用使微藻种群数量显著降低;扑草净暴露减弱了海水小球藻对三角褐指藻的竞争抑制且暴露于环境浓度(0.5和5μg/L)扑草净12d后便可导致海水小球藻和球等鞭金藻共培养体系中的敏感种球等鞭金藻全部消亡,最终使得种间作用向着更有利于硅藻的方向发展.研究结果为评估三嗪类除草剂扑草净的海洋生态风险提供了理论支撑.

In this study,effects of prometryn on the population dynamics,photosynthetic capacity,and interspecific competition of three marine microalgae species,including Phaeodactylum tricornutum,Chlorella pacifica,and Isochrysis galbana,were evaluated based on the monoculture experiment and the co-culture experiment with two microalgaes(cell density ratio1:1).The results showed that the 96h-EC50 values of prometryn for P.tricornutum,C.pacifica,and I.galbana were 7.65,16.67,and 4.11μg/L,respectively;and the toxicity from high to low was as follows:I.galbana>P.tricornutum>C.pacifica.Prometryn exposure significantly inhibited the photosynthesis of these three microalgaes and thereby reduced their population growth.In addition,prometryn treatment also weakened the competitive inhibition of P.tricornutum by C.pacifica in the co-culture group and during the cocultivation of C.pacifica and I.galbana exposed to environmental concentrations(0.5 and 5μg/L)of prometryn for 12 days,an extinction of the sensitive species I.galbana was observed,indicating an interspecific interaction more favorable to diatoms.Overall,this study would provide more theoretical support for assessing the marine ecological risk of the triazine herbicide prometryn.