A bloom-forming freshwater diatom: <i>Achnanthidium catenatum</i>

Abstract

作为区域重要饮用水源的浙江绍兴汤浦水库于2010年5月期间暴发以硅藻和蓝藻为主的藻类水华.对库尾、库中和坝前3处浮游植物样品进行采集和分析,结果表明,汤浦水库浮游植物密度在1.13×108~1.56×108cells/L之间,水华优势种之一为我国大陆地区首次报道的羽纹纲硅藻——链状弯壳藻(Achnanthidium catenatum),另一种为丝状蓝藻——湖泊假鱼腥藻(Pseudanabaena limnetica),两者的平均相对丰度分别为65.6%和28.2%;链状弯壳藻是弯壳藻属中唯一适应浮游生长的种类,具有独特的带面观,能以壳面相连形成2~3个细胞的短链状群体;对国内外3次链状弯壳藻为优势种的水华案例进行分析,发现该藻为广温性种类,适应低光强和低磷浓度生长;水华生消机理则需进一步研究.;In May 2010, algal bloom dominated by diatom and blue-green algae broke out in Tangpu Reservoir,which is the drinking water resource of Shao Xing,Zhejiang Province.Phytoplankton samples collected from 3 sites(Kuwei,Kuzhong,and Baqian) along the flow direction were investigated.The phytoplankton density ranged between 1.13×108 and 1.56×108 cells/L.The dominant species Achnanthidium catenatum(Bílý et Marvan) is a pennatae diatom,which was first reported from mainland in China.Another dominant species Pseudanabaena limnetica belongs to filamentous cyanobacteria,and their average relative abundances were 65.6% and 28.2%,respectively.Achnanthidium catenatum is the only planktonic species of the genus Achnanthidium showing distinctive girdle view and colonies consisting of a maximum of 3 frustules.Case studied of three different Achnanthidium catenatum blooms indicated that this species was eurythermal and adapted to lower light intensity and phosphorus concentration.Further study should shed more lights on the formation and disappearance mechanisms of this algal bloom.