夏季率水浮游动物群落类型及影响因素

于2018年8月在率水设置了19个采样点,进行后生浮游动物标本采集和水质指标测定.共记录浮游动物22种,隶属2门19属,其中轮虫17属20种,桡足类2属2种,枝角类未检出.浮游动物丰度很低,在7～1 675 L~(-1)之间变动,平均丰度仅123 L~(-1).其中,轮虫是对率水浮游动物群落物种组成和生物量贡献最大的类群.率水浮游动物群落从上游到下游的空间分布不均匀,种类和丰度都表现为中游略高于上下游.基于物种组成对所有样点的群落进行聚类分析,划分为5种不同的群落类型,群落间特征差异较大.基于指示种的组成和丰度进行水质评价表明:率水水质介于寡(o)污染到寡-中(o-β)污染水平之间.冗余分析表明:溶解氧(DO)、溶解性物质及相关指标(总溶解性固体(TDS)、盐度(Sal)、电导率(SpCond))和化学需氧量(COD_(Mn))是影响浮游动物群落的重要环境因子.

Types of zooplankton community and influencing factors in summer in Shuaishui River

In August 2018,we set 19 sampling sites in Shuaishui River which is the biggest tributary of Xin''an River,to collect zooplankton samples and measure in situ physicochemical variables.The results showed that a total of 22 species belonging to 2 families 19 genera were recorded from Shuaishui River.Of them 20 species in 17 genera belong to Rotifera,and 2 species in 2 genera belong to Copepods.There were no Cladocera species found from the river.The abundance of zooplankton in the river was quite low (average value:123 L^-1,varied between 7~1 675 L^-1).Rotifer contributed most to zooplankton species composition and biomass of the river.Distribution of zooplankton community was not even spatially,and both species richness and abundance of zooplankton in midstream were slightly higher than those in up- and down-streams.Based on species composition,the communities in all the sample sites were clustered and divided into five quite different community types.Zooplankton abundance varied among groups.Water quality assessment results based on the species composition and abundance of indicator species indicated that Shuaishui River was at the level of o-oligomeric pollution or o-beta oligo-middle pollution.Redundancy analysis (RDA) showed that indicators,such as dissolved oxygen (DO),dissolved matters and related variables(TDS:total dissolved solids;Sal:salinity;SpCond:conductivity)and COD_Mn (chemical oxygen demand) were vital environmental factors affecting zooplankton community.