象山港南沙岛不同养殖模式沉积物微生物群落结构分析

通过构建16S rDNA克隆文库对象山港南沙岛不同养殖模式(贝类养殖、藻类养殖及网箱养殖)表层沉积物微生物多样性和群落结构特征进行了比较和分析,共获取136个OUT。其中,贝类养殖区、藻类养殖区和网箱养殖区OTU分别为58、48和57个。各站位OTU分布差异明显,表现出高度的多样性。基于16S rDNA序列的生物多样性和丰富度分析表明,网箱养殖区丰富度指数ACE为739,香浓指数H?为3.8,均为最高值,丰富度指数Chao为245,略低于于贝类养殖区。贝类养殖区丰富度指数Chao为303,在各养殖区中最高。藻类养殖区丰富度指数ACE为174、Chao为89,香浓指数H?为3.6,均为最低值。系统发育分析表明,南沙岛各养殖区的优势种群均为变形菌门(Proteobacteria),但是藻类养殖区微生物群落结构与其他养殖区域相比,16S rDNA克隆文库差异显著,其中根瘤菌属(Rhizobium)及其他光合细菌在藻类养殖区分布较多。网箱养殖区沉积物表层微生物群落中出现了与环境污染密切相关的菌群,如志贺氏菌属(Shigella)、埃希氏菌属(Escherichia)和ε-变形菌纲的微生物种群,揭示网箱养殖对底质沉积物环境的影响较大。

The Structures of Sediment Microbial Communities in Different Mariculture Models at Xiangshan Bay of China

Xiangshan Bay, the biggest marine aquaculture base in Zhejiang Province, is a semienclosed bay with slow water exchange rate. In the center of Xiangshan Bay lies Nansha Bay where a variety of mariculture models are applied. To better understand the structures and diversity of sediment microbial communities in different mariculture models, we constructed the 16 S rDNA clone library for the analysis of samples from the shellfish culture, the seaweed culture and the fish cage culture. We obtained 136 OTUs from three sampling models that included 58 OTUs from the shellfish culture, 48 from the seaweed culture, and 57 from the fish cage culture. The distribution patterns of OTUs were highly different between the three sampling models which indicated the distinct microbial community structures. The calculation of species richness（Chao）, evenness（ACE）, and diversity（Shannon） were 245/739/3.8（fish cage culture）, 313/330/3.6（shellfish culture） and 89/174/3.6（seaweed culture） respectively. This suggested that the diversity of 16 S rDNA gene clone libraries of seaweed culture model was the lowest among all three models. The results of the phylogenetic analysis showed that proteobacteria were the dominant microbes in all sampling models. The microbial community structure of the seaweed culture model differed obviously from those of the shellfish culture and the fish cage culture models. Rhizobium and some photosynthetic bacterial sequences were abundant in the seaweed culture clone library. Moreover, microbes closely related to sediment pollution were found in the fish cage culture model, such as Shigella, Escherichia, and ε-Proteobacteria. This implied that the fish cage culture could be the major source of pollution in the sediment of Nansha Bay.