基于着生硅藻多参数指标评价赤水河生态状况

随着人类活动的加剧,赤水河生态状况受到越来越多的关注,全面了解赤水河的生态状况,识别影响生态状况的主要环境胁迫因子对于赤水河的管理十分重要。笔者分别于2016年春季(4月)和秋季(9月)对赤水河干流着生硅藻及主要环境指标展开系统调查,春季以曲壳藻属相对丰度、高需氧物种、高磷物种、Shannon-Wiener多样性指数为核心参数,秋季以低需氧物种、物种丰富度、高营养物种为核心参数,构建了着生硅藻多参数指标(D-MMIs)。对赤水河干流生态状况进行评估。结果表明:调查期间,赤水河干流中上游样点水体状况优于下游样点,并且春、秋季赤水河生态状况存在差异。D-MMIs与环境因子的回归分析结果显示:影响春季赤水河生态状况的环境因子为COD,影响秋季赤水河生态状况的环境因子为NH4^+-N。构建的赤水河D-MMIs,能够较好地指示环境胁迫因子对赤水河生态状况的影响,对于指导赤水河的管理实践具有参考价值。

Using Benthic Diatom-Based Multi-metric Indices to Assess Ecological Conditions of the Chishui River

Ecological conditions of the Chishui River have been increasingly concerned due to more intensive human disturbance in the watershed recent years. Identification of the major environmental stressors affecting ecological conditions is importance for the management of Chishui River. We surveyed benthic diatom assemblages and major environmental variables in the main stream of the Chishui River in spring (April) and autumn (September) of 2016,and developed diatom-based multi-metric indices (D-MMIs) to evaluate ecological condition of the river. The D-MMIs for spring was developed with relative abundances of Achnanthes,high oxygen demand indicator species,high phosphorus species,and Shannon-Wiener diversity index. In contrast,the D-MMIs for autumn was composed of low oxygen demand indicator species,species richness,and eutrophic indicator species. Generally,D-MMIs indicated that ecological conditions of the up- and middle-stream sites were better than that of the downstream sites in both seasons,with certain degree of seasonal variation. The regression relationships between D-MMIs and environmental variables showed that the major environmental stressors affecting ecological conditions of the Chishui River in spring were COD,with NH⁺₄-N the most influential variable in autumn. The D-MMIs are effective in indicating impacts of environmental stressors on ecological conditions of the Chishui River,therefore,our research is valuable for guiding management of the river.