东海藻华高发区塔玛亚历山大藻(Alexandrium tamarense)的形态、分子及分布特征

MORPHOLOGICAL-PHYLOGENETIC ANALYSIS AND POPULATION DYNAMICS OF ALEXANDRIUM TAMARENSE IN THE BLOOM AREA OF THE EAST CHINA SEA

本文对分离自我国东海藻华高发区的亚历山大藻进行了详细的形态特征描述和分子系统进化分析,通过运用光学显微镜、荧光显微镜、扫描电镜和分子生物学方法,确定该藻株为塔玛亚历山大藻Alexarium tamarense(Lebour)Balech,并对其ITS序列进行了系统进化分析。该藻体长21—35μm,体宽20—33μm,ITS序列长度为592bp,系统发育树中与中国东海、南海两株A.tamarense以及一株代表"亚洲温带"基因型的A.catenella聚合在一起,支持率为100%,形态特征与A.tamarense基本一致,核糖体基因型则为塔玛复合种"亚洲温带"基因型。通过现场观测,研究浙南至闽北东海藻华高发区的塔玛亚历山大藻分布变化特点,在东海原甲藻藻华消散期,塔玛亚历山大藻逆势而上,其细胞密度达到1.7×104cell/L,并逐渐向沿岸靠近,这与季风转向,台湾暖流入侵及水体层化密切相关。

We isolated and described Alexandrium tamarense Balech(LAMB130428) from the HAB area of East China Sea morphologically and phylogenetically in molecular level for taxonomic specifications using light microscopy, fluorescence microscopy, and scanning electron microscopy. The cell dimension are 21—35μm in length with 20—33μm in width. The ITS sequences of strain is 592 bp. The phylogenetic tree suggests that the strain is clustered with two strains of A. tamarense of the South China Sea and A. catenell(a genotype of 'Temperate Asian') in a high bootstrap value(100%). Morphologically in molecular scope, the strain was confirmed as A. tamarense as a genotype of 'Temperate Asian'. Cell density of A. tamarense ranges 1.0×103—1.7×104cell/L in the areas of South Zhejiang and North Fujian of China. The A. tamarense population kept increasing while Prorocentrum donghaiense bloom decreasing until the end of May. The relative high-density area of A. tamarense moved gradually coastward, which is very likely related to the physical driving forces, such as change of monsoon direction, Taiwan Warm Current invasion, and water stratification as well.