涡河中下游浮游动物群落结构及水生态评价

浮游动物群落结构是定量描述河道水生态系统功能的重要指标,动物种类及现存量变化能灵敏地反映水域生态环境的动态变化。为探究涡河中下游浮游动物群落结构及其影响因素,于2016年12月至2017年9月分季度监测了其群落组成和水质变化,根据涡河中下游水闸的位置,将整个涡河划分为5个河段,每个采样河段均设置2个采样点,共计10个样点;采用浮游动物种类、密度、生物量和多样性指数,对涡河水体的营养状态和污染情况进行了评价,通过群落指标与水质指标的冗余度,识别群落结构的影响因子。结果表明:(1)涡河中下游4次采样共检测出浮游动物56种,其中原生动物13种,轮虫20种,枝角类13种,桡足类10种;(2)4个季度的生物量为0.12～8.87 mg/L,均值为1.78 mg/L;Shannon-Wiener多样性指数为0.22～3.17,均值为2.13;水体整体处于中度富营养状态,污染指数为中污型;(3)春季的浮游动物优势种数较其他三季高,春季多样性指数较夏冬略高,明显高于秋季;(4)义门镇采样点秋季多样性指数接近于严重污染状态,城西镇、高炉镇采样点秋季多样性指数均处于严重污染状态,广布多肢轮虫为3个采样点的绝对优势种,在水质治理中应引起重视;(5)冗余度分析表明,环境因子对浮游动物时空分布的总体变异解释度为60.70%,流速、水温和溶解氧是影响涡河中下游浮游动物群落结构的主要环境因子。

Zooplankton Community Structure and Aquatic Ecological Evaluation in the Middle and Lower Guohe River

Zooplankton community structure is an effective means of assessing the condition of a river ecosystem, and changes in zooplankton species reflect ecosystem dynamics. Guohe River, crossing Henan and Anhui Provinces, is the second largest tributary of Huaihe River. In this study, seasonal monitoring of the zooplankton community and water quality in the Anhui section were conducted at 10 sampling sites in December 2016 and March, June and September 2017. The trophic and pollution status of the middle and lower Guohe River were evaluated based on the zooplankton species present and indices of density, biomass and diversity. In addition, the environmental factors affecting zooplankton community structure were identified by redundancy analysis. The objective was to provide technical support for the conservation and sustainable development of water resources in the middle and lower Guohe River. The results can be summarized as follows: (1) A total of 56 zooplankton species were identified in the middle and lower Guohe River during the investigation; 13 protozoans, 20 rotifers, 13 cladocerans and 10 copepods. (2) The mean value and range (in parentheses) of zooplankton biomass were 1.78 mg/L (0.12 - 8.87 mg/L) and the values of the Shannon-Wiener diversity index were 2.13 (0.22-3.17), indicating conditions in the middle and lower Guohe River were moderately eutrophic and moderately polluted. (3) The number of dominant zooplankton species was highest in spring and the spring diversity index was slightly higher than in summer and winter, but markedly higher than in autumn. (4) The diversity index at the Yimen sampling site in autumn was near the criterion for serious pollution status and the diversity index at the Chengxi and Gaolu sampling sites did meet the criterion. At these three sampling sites, the dominant species was Polyarthra vulgaris, a rotifer indicating organic pollution and nutrient enrichment. (5) Redundancy analysis showed that environmental factors explained 60.7% of the overall variation in the spatiotemporal distribution of the zooplankton community and the primary factors were flow velocity, water temperature and dissolved oxygen.