渭河丰、枯水期底栖动物群落特征及综合健康评价

以渭河为研究范例,分别于丰水期(2011年10月)和枯水期(2012年4月)对渭河全流域范围内45个样点的底栖动物群落进行跟踪调查,并在此基础上应用丰、枯水期底栖动物生物完整性评价指数(B-IBI)对渭河流域水生态系统进行综合健康评价。结果表明,渭河流域底栖动物群落结构具有明显的空间异质性,枯水期底栖动物群落结构单一,物种数量、生物量和香农多样性明显少于丰水期,但单位密度差异不显著。综合健康评价结果表明,渭河上游、洛河中上游地区的健康状况较好,而渭河中下游、泾河全流域及洛河下游地区的健康状况较差。相关分析显示,渭河全流域范围内丰水期和枯水期底栖动物群落的B-IBI得分呈现明显的正相关性,表明在不同水文过程时期,渭河全流域大尺度范围内底栖动物群落的生物完整性特征较为一致。在河流丰、枯水期,底栖动物群落结构的变化趋势并对比分析了渭河流域不同区域水生态系统健康水平差异的原因。

Community structure and biological integrity of macroinvertebrates in the wet and dry seasons of Wei River basin, China

Biological community structures have long been used to assess the impact of human activity on running waters. Although there were several studies using macroinvertebrate to assess the river conditions, the influence of hydrological factors, e.g. rate of flow, on community structure of macroinvertebrate and river health received little attention. In the present work, we investigated the community structure of macroinvertebrate and characteristics of environmental factors among 45 sampling sites in the Wei River Basin, Northwest China during wet season (October, 2011) and dry season (April, 2012). We also assessed the stream conditions of Wei River in the wet and dry seasons based on the Index of Biological Integrity (B-IBI). The results indicated that there was great heterogeneity in the structure of macroinvertebrate community in Wei River. The common species were Baetis vaillanti, Serratella sp., Leptophlebia sp., Cinygma sp., Pteronarcyidae, Hydropsychidae, Glossosomatidae, Cricotopus trifasciatus, Alotanypus venustus, Chironomus semireductus, Radix swinhoei, Radix ovata and Polypylis hemisphaerula. The structure of macroinvertebrate community in dry season is simplified. The results of boxing analysis showed that species richness, biomass and Shannon index were significantly higher in wet season than in dry season in the Wei River basin. However, the density of macroinvertebrate was similar in both seasons. The results of B-IBI showed that upstream of Wei River was of excellent ecological integrity, while the midstream and downstream of Wei River were in severe impairment. Though the biological integrity of macroinvertebrates in Jing River and downstream of Luo River was in severe impairment, the upstream of Luo River was in relatively good biological integrity. The score of B-IBI all over the Wei River basins showed positive correlations between wet and dry season. In this paper, we also discussed the influence of water flow and flux on the dynamic characteristics of macroinvertebrate community in wet and dry season. Moreover, the possible reasons that caused the difference in biological integrity of macroinvertebrate community in the Wei River Basin were further discussed.