环境因子对供水水库原生动物群落特征的影响

为探究水库环境因子对原生动物群落特征的影响,2016年对浙江汤浦水库进行逐月全年采样,从上游库尾至下游坝前共设6个调查站位。结果表明,汤浦水库检出原生动物37种,隶属5纲、18科、22属;群落种类数呈现双峰型,夏季最高,秋季次之,春冬季相对较低;密度年均值为1 608个/L,呈现单峰型,高峰值出现在8月,食菌功能类群在夏季占比最高,夏秋季高于春冬季。水库纵向分布呈现种类数及密度均为上游高于中下游的特点,6月空间异质性处于最高水平。优势种分析表明,食菌功能类群的旋回侠盗虫(Strobilidium gyrans)、王氏似铃壳虫(Tintinnopsis wangi)、小筒壳虫(Tintinnidium pusillum)及膜袋虫(Cyclidium sp.)优势明显。典范对应分析(Canonical Correspondence Analysis,CCA)前置选择发现,30个环境因子中,总氮、水温、藻类细胞数、总硅和浊度是影响汤浦水库原生动物群落结构的重要环境因子。Spearman秩相关分析结果显示,原生动物密度与藻类细胞数和水温呈显著正相关,而与总氮呈显著负相关。水库的3个雨季及6月泄洪阶段,是促使夏季原生动物高峰期出现的一个重要原因,营养状况差异是造成原生动物时空分布差异的主要原因。

Effects of Environmental Factors on the Protozoan Community in a Water Supply Reservoir

Protozoa are zooplankton characterized by small size, simple structure and sensitivity to environment change. As an important indicator of nutrient pollution, protozoans are widely used for evaluating water quality in reservoirs. In 2016, we carried out a monthly investigation of the spatial-temporal distribution of the protozoan community structure and water quality parameters in Shaoyu Plain water supply reservoir-Tangpu Reservoir. The objectives were to study the effect of environmental factors on protozoan community structure, determine the trophic status of Tangpu Reservoir and provide a scientific basis for protecting water quality in Tangpu Reservoir. Six sampling sites were set, from the upper channel to the dam, and water and protozoan samples were collected mid-month for determination of physiochemical parameters and analysis of protozoan community structure. A total of 37 protozoan species were collected, belonging to 22 genera, 18 families and 5 classes. The species richness of protozoa displayed a bimodal pattern, with the highest richness in summer (June-August) and then autumn (September-November). The annual average density was 1608ind/L, with a single peak in August. The proportion of the fungi-eating functional group was highest in summer, and much higher in summer and autumn than in spring (March-May) and winter (December- February). Spatially, species number and density in the upper reaches were higher than those in the middle and lower reaches of the reservoir and spatial heterogeneity was highest in June. From the fungi-eating functional group, Strobilidium gyrans, Tintinnopsis wangi, Cyclidium sp. and Tintinnidium pusillum were the dominant species and were clearly advantaged within the community. Canonical correspondence analysis (CCA) indicated that total nitrogen, water temperature, algae cell number, total silicon and turbidity were the environmental factors most affecting protozoan community structure in Tangpu Reservoir. Protozoan density was positively correlated with algae cell number and water temperature, but negatively correlated with total nitrogen. Rainfall during the rainy season and flood discharge in June were the primary factors accounting for protozoan peak in summer. Difference in nutrient level was the main reason for differences in spatial and temporal distribution of protozoa community in Tangpu Reservoir.