两种沉水植物附着生物种群特征对水深的响应研究

选取浅水湖泊中两种常见沉水植物上的附着生物作为研究对象,通过显微观测和16S rRNA高通量测序的方法,探究原位实验条件下水深(分别以T1、T2、T3、T4代表0.6、1.2、1.8和2.4 m)对狐尾藻(Myriophyllum spicatum)和马来眼子菜(Potamogeton malainus)附着藻类和附着细菌种群组成及其多样性特征的影响.结果表明,沉水植物附着生物种群特征与水深和生物种类有关,试验组中所有水深梯度下的狐尾藻附着生物群落的自养指数(AI)均大于马来眼子菜,且试验组中较小水深0.6~1.2 m的AI值较高,较大水深1.8~2.4 m的AI值较低.两种沉水植物表面附着藻类组成随水深变化差异显著(p0.05),绿藻门和硅藻门仍占种群绝对优势;附着细菌种群随水深梯度的变化差异也显著(p0.05),但主要包括有Proteobacteria、Firmicutes和Bacteroidetes等优势菌群,同种沉水植物或相似水层深度间的附着细菌组成和丰度有较高的相似性,并且试验组中较小水深0.6~1.2 m中拥有更多特有的细菌种类.研究发现,相同水深时狐尾藻附着藻类的多样性大于马来眼子菜,而马来眼子菜附着细菌多样性大于狐尾藻,且位于中等水深1.2~1.8 m时两种沉水植物附着藻类和附着细菌的多样性往往最高.通过水深对沉水植物附着生物种群特征影响的研究,可为揭示沉水植物表面微生态作用规律提供参考.

Research on characteristics of epiphytic organism of two submerged macrophytes and its response to water depth

Two kinds of dominant submerged plants'' epiphytic organism were selected as the research objects in Gehu Lake in Changzhou. Based on the way of microscopic count and 16S rRNA high throughput sequencing, the influence of water depth(T1, T2, T3 and T4 respectively referred to 0.6, 1.2, 1.8 and 2.4 m) was investigated on Myriophyllum spicatum and Potamogeton malainus epiphytic algae and bacteria''s composition and diversity. The results showed that the distribution of microbial communities on surface of submerged plant were related to the water depth and species, the autotrophic index of Myriophyllum spicatum were larger than Potamogeton malainus under any water depth gradient in the test groups. Furthermore, the AI value of the small depth (0.6~1.2 m) was higher, the AI value of the medium and large water depth (1.8~2.4 m) was lower in the test groups. There were significant difference in epiphytic algae composition between two submerged macrophytes with water depth (p<0.05), the community of epiphytic algae living on two submerged macrophytes were dominated by Chlorophyta and Bacillariophyta. Significant difference was also found in epiphytic bacteria composition between two plants with water depth (p<0.05), in which most of bacterial were Proteobacteria, Firmicutes, Bacteroidetes and so on. There was a high similarity of the epiphytic bacteria''s composition and abundance between the same plant and the water layer, more unique bacterial species were found in the small water depth (0.6~1.2 m). It indicated that the diversity of epiphytic algae in Myriophyllum spicatum was larger than that in Potamogeton malainus, on the contrary, the diversity of epiphytic bacteria in Myriophyllum spicatum was more lower. The diversity of two plants'' epiphytic algae and epiphytic bacteria was often the highest in the medium water depth (1.2~1.8 m). Strengthening the research on the characteristics of water depth on the epiphytic organism living on submerged macrophytes, it was reference to explore the mechanism of surface microecology in submerged macrophytes.