基于着生藻类的太子河流域水生态系统健康评价

Using periphyton assemblages to assess stream conditions of Taizi River Basin,China

以辽宁省太子河流域为研究范例,调查了全流域范围内69个样点的着生藻类群落和水环境理化特征,并在此基础上应用硅藻生物评价指数(DBI)和生物完整性评价指数(P-IBI),同时结合栖息地环境质量评价指数(QHEI),对太子河流域水生态系统进行健康评价。结果表明,太子河流域着生藻类群落结构具有明显的空间异质性,CCA结果显示驱动着生藻类群落结构形成的水环境因子为电导率、总溶解固体和总氮。虽然DBI、P-IBI和QHEI在太子河流域某些河段上的评价结果有较大出入,但从全流域尺度上看,DBI、P-IBI和QHEI的评价结果基本一致,表现为太子河上游健康状况较好,中游健康状况一般,而下游健康状况较差。讨论了水环境理化因子与着生藻类群落结构的相互关系,并对比分析了DBI、P-IBI和QHEI这3种河流健康评价方法。

Biological community structures have long been used to assess the impact of human activity on running waters. Compared to macroinvertebrates and fish community, periphyton community was infrequently used as indicator of stream conditions because of the large number of species and the need for taxonomic expertise. However, periphyton is valuable indicator of stream health because they are relative simple to collect and response rapidly and predictably to changes in stream chemistry and habitat quality. In the present work, we investigated the community structure of periphyton and characteristics of environmental factors among 69 sample sites in Taizi River Basin of Liaoning Province, Northeast China. Using the periphyton assemblages, we assessed stream conditions of Taizi River Basin based on Qualitative Habitat Evaluation Index （ QHEI）, Diatom Bioassessment Index （DBI） and Periphyton Index of Biological Integrity （PIBI）. The results indicated that the dominant species of periphyton in Taizi River Basin were Melosira varians, Diatoma vulgare , Cymbella tumida , C. hustedtii , Navicula cryptocephala , Gomphonema olivaceum , Achnanthes minutissima , Synedra acus , S. ulna, S. ulna oxyrhynchus , Nitzschia palea , Cocconeis placentula , Scenedesmus quadricauda , Oscillatoria tenuis and Phormidium tenus. There was great difference in the periphyton community structure in Taizi River Basin. Based on principal component analysis, conductivity, suspended solid, velocity, total dissolved solid, hardness, alkalinity, ammonia nitrogen, nitric acid nitrogen and total nitrogen were the main environmental factors in Taizi River Basin.Canonical correspondence analysis showed that conductivity, total dissolved solids and total nitrogen significantly influenced the community structure of periphyton in Taizi River Basin. The metrics of DBI were species richness, diversity index, tolerance index, sensitive species and similarity of community, and the metrics of QHEI were epifaunal substrate, embeddedness, velocity, sediment deposition, channel flow status, channel alteration, frequency of riffles, bank stability, vegetative protection and riparian vegetative zone width. The merits of P-IBI were filtered with box-plots analysis and correlation analysis, and the ultimate index merits of P-IBI were total genera of green algae, relative species richness of sensitive diatoms, relative richness of diatom taxons, relative richness of blue-green algae taxons, percent of Nitzschia, percent of Oscillatoria, percent of motile diatoms, percent of diatoms with handle, Chlorophyll a content of periphyton and cell density of periphyton. The results of stream condition assessment based on DBI, PIBI and QHEI were in consensus in Taizi River Basin, although assessment results of some tributary were not in compatible. The results of stream condition assessment showed that upstream area of Taizi River Basin were in excellent ecological integrity, while, the downstream area of Taizi River Basin were in severe impairment. The results of correlation analysis showed that there were significant correlations among the scores of DBI, P-IBI and QHEI in sample sites of Taizi River Basin, and moreover, significant correlations were also detected between scores of DBI, PIBI, QHEI and conductivity, total dissolved solid and total nitrogen. In the paper, we also discussed the relationship between periphyton community structure and environmental factors, and moreover, we evaluated the merit and deficiency of DBI, PIBI and QHEI in the assessment of stream conditions of Taizi River Basin.