拉林河流域底栖硅藻群落结构特征及水生态健康评价

随着农业活动的发展，对水域生态系统评估成为受农业活动影响区域水环境管理的有效手段.以我国东北典型水稻种植区拉林河流域为研究区域，调查分析了全流域范围河流内23个样点的底栖硅藻群落结构和水环境理化特征，基于优势种和理化指标的冗余分析（RDA）揭示了底栖硅藻群落生态分布特征并对关键影响因子进行识别.在此基础上应用底栖硅藻生物完整性指数（D-IBI）对拉林河流域水生态系统健康状况进行评价，并分析了底栖硅藻在农业活动区和非农业活动区下的群落结构及不同土地利用类型下的D-IBI.研究结果表明，拉林河流域底栖硅藻群落结构具有明显的空间差异性；D-IBI评价结果显示，拉林河流域水体整体健康状况为一般，农业活动会影响河流生态健康状况.其中，拉林河上游为健康，中游区域为较好至一般，下游区域轻度污染至重度污染.D-IBI和多数环境因子及IBI核心指标有显著或极显著的相关关系，能较好地反映研究区域环境信息，并适用于受农业活动干扰的拉林河流域生态健康评价.

Characteristics of Benthic Diatom Community Structure and Water Ecological Health Evaluation in the Lalin River Basin

With the improvement of public requirements for the health status of aquatic ecosystems, there have been innovative assessment methods developed for aquatic ecosystems. In this study, benthic algae assemblages and water quality variables were analyzed to develop a benthic diatom-based index of biotic integrity (D-IBI) for the assessment of the aquatic environment in the Lalin River. In addition, using redundancy analysis (RDA) based on dominant species and physicochemical indexes, the ecological distribution characteristics of the benthic diatom community were revealed, and the key influencing factors were identified. The results showed that the benthic diatom community structure in the Lalin River basin had obvious spatial differences. The application of the index revealed that the water quality could be described as excellent condition in the upper reaches of the Lalin River, good to common condition in the middle of the sites, and moderate to poor condition in the downstream. The assessment further revealed that the main reason for the degradation of the Lalin River ecosystem was nutrient enrichment through agricultural land use.