三种常见原生动物对褐潮藻种抑食金球藻(Aureococcus anophagefferens)的摄食

Grazing of three common protozoan on brown tide alga Aureococcus anophagefferens

微型浮游动物在抑食金球藻(Aureococcusanophagefferens)引发褐潮时表现的摄食压力可潜在控制褐潮的爆发和消亡。本研究就三种海洋常见原生动物——海洋尖尾藻(Oxyrrhis marina)、海洋尾丝虫(Uronema marinum)和扇形游仆虫(Euplotes vannus)——对单种饵料及混合饵料中抑食金球藻中国株的摄食进行了研究。单种抑食金球藻指数期细胞喂食的三种原生动物的生长率和摄食率呈现米氏方程变化趋势。比较三种原生动物摄食抑食金球藻的最大摄食率,发现其随动物粒径的增大而增大,但仅为摄食球等鞭金藻(Isochrysis galbana)的30%～59%。海洋尖尾藻和海洋尾丝虫的最大生长率(μmax)与饵料种类无关,扇形游仆虫摄食抑食金球藻时的μmax值小于摄食球等鞭金藻的个体。海洋尖尾藻、海洋尾丝虫和扇形游仆虫摄食抑食金球藻时的毛生长率(gross growth efficiency, GGE)分别为65.8%、35.2%和49.1%。三种原生动物摄食抑食金球藻指数期细胞和球等鞭金藻以不同比例混合的饵料时表现出对抑食金球藻的选择倾向;在含有抑食金球藻稳定期细胞的混合饵料喂食的情况下,三种原生动物避食抑食金球藻或不表现明显摄食倾向性。抑食金球藻释放胞外聚合物(extracellular polymeric substance, EPS)的测定结果显示,细胞从指数期生长至稳定期释放出的EPS的水平显著上升(P<0.05),可能与原生动物对不同生长期藻细胞具有不同选择偏好有关。

With the increase of marine plastic waste,marine microplastics have attracted more and more attention as a new type of marine pollution.At present,studies of the source,distribution and analytical approach of microplastics are well recognized.Most research focuses on plastic ingestion by marine organisms,and on the effects of microplastics adsorbing and releasing toxic chemicals.However,the role of microplastics as a vector for pelagic microorganism,phytoplankton and micozooplankton is poorly understood.In this review,we address three functions of microplastics as a biological vector.1)Aggregation,it is easy for biofilms to form a microbial community on the surface of microplastics,which provide the means for horizontal transfer of organisms and genes,and may lead to the transformation or transduction of pathogenic gene,antibiotic resistance gene(ARGs),called genetic exchange.2)Dispersal,the spread of harmful algal species,pathogenic bacteria and drug-resistant bacteria as well as other microorganisms may happen when the microplastics are freshly from the waste water flow,which potentially poses a risk of invasion when arriving in a new habitat with favorable condition.3)A feeding enhancement concept,we propose this concept because a piece of microplastics is full of the attached biofilms,nutrients and organisms,which may attract large grazers or predators and can also improve their predation efficiency.As a result,these grazers/predators may seek pieces of microplastic as foods,which may cause more serious toxicological effects.The review focuses on the ecological effects of“microplastic+biology”.