夏季漓江不同底质类型和沉水植物对底栖动物分布的影响

2012年8月对漓江流域的河床底质、沉水植物、底栖动物和相关环境因子进行了调查,共采集了8个区域,底质类型分为淤泥、卵石、砾石3种底质,植物类型分为无水草(No plant)、亚洲苦草(Vallisneria spiralis)、轮叶黑藻(Hydrilla verticillata)、亚洲苦草+轮叶黑藻(Vallisneria spiralis+Hydrilla verticillata)4种类型,共采集大型底栖动物42种,隶属6纲34属,采用物种相似性、密度和生物量、功能摄食类型、多样性指数等参数,利用CLUSTER、NMDS和单因素方差(One-way ANOVA)分析方法,研究底栖动物在不同区域的差异.不同底质中的底栖动物物种组成、密度、生物量、功能摄食类型相对丰度、Shannon-Wiener指数和Margalef物种丰富度指数都有明显差异,尤其是淤泥底质差异显著(p0.05);在相同底质中,沉水植物的存在使底栖动物物种相似度、生物量、滤食者相对丰度有一定增加,总密度有一定程度的减小;在卵石底质中,轮叶黑藻中的底栖动物总生物量、功能摄食类型相对丰度和亚洲苦草中差异较大;在砾石底质中,亚洲苦草和亚洲苦草+轮叶黑藻中的底栖动物参数差异很小.通过冗余分析(RDA)能较好的解释差异的产生,底质类型对底栖动物分布的影响比沉水植物类型大,而且两者有较强的交互作用.

Effects of different bottom sediment and submerged macrophytes on macrofauna communites in the Lijiang River during the summer

Samples of the riverbed, submerged macrophyte, macrofauna and environmental factors were taken from eight places located in the upper, middle and down reaches in the Lijiang River in August 2012. The riverbed samples were classified into silt, pebble and gravel. The submerged macrophyte types were categorized into: No plant, Vallisneria spiralis, Hydrilla verticillata, and Vallisneria spiralis+ Hydrilla verticillata. The macrofauna belonged to 6 classes, 34 genera and 42 species. Species similarity, density, biomass, functional feeding group and diversity were used as indices for comparison of macrofauna community differences between the eight places. Analysis was performed using CLUSTER, NMDS and one-way ANOVA methods. Results show that macrofauna taxon composition, density, functional feeding group, and species diversity had significant variations in different bed, with those in silt being especially different than in pebble and gravel. In silt, macrofauna taxon composition, biomass, relative abundance of filter-collectors were higher where submerged macrophyte were present, but the total density was lower. In pebble, the total biomass and functional feeding group had obvious difference between Hydrilla verticillata and Hydrilla verticillata. In gravel, all the indices had little difference between Vallisneria spiralis and Vallisneria spiralis+ Hydrilla verticillata. The analysis of the RDA(Redundancy analysis)can well explain the differences among the eight places, namely demonstrating that the influence of bed types on the distribution of macrofauna was larger than submerged macrophyte, and that the two factors had strong interactions.