应用鱼类生物完整性指数评价黑水河河流健康状况

黑水河为金沙江下游一级支流，是白鹤滩库区干流鱼类的重要替代生境和优先保护支流。为评价黑水河河流健康状况，于2018年11月至2019年9月在黑水河23个采样点开展了4次鱼类资源调查，共采集到鱼类45种，隶属于4目10科33属。以黑水河河口、水文站上游和825回水点作为参照点，经过分布范围、判别能力及相关性分析等指标构建黑水河鱼类生物完整性指数（F-IBI）评价体系。使用1、3、5赋值法和比值法计算各采样点的IBI分值以评价各采样点健康状况，结果显示，1、3、5赋值法和比值法的结果虽然不完全相同，但趋势是一致的。黑水河大部分采样点的健康状况处于“较差”和“一般”水平。Pearson相关性分析结果显示：F-IBI分值与海拔呈显著负相关（P<0.01）。丰度生物量比较曲线显示，黑水河鱼类群落结构整体上受到中度干扰。评价结果与河流实际情况相符合，可为黑水河的环境保护和监测提供科学依据。

River health assessment using biotic integrity index based on fish for Heishui River

Heishui River is a tributary of the Lower Reach of Jinsha River and it is an important alternative habitat and a priority tributary for protection of fish in the mainstream of the Baihetan reservoir area. However, the biological integrity of fish in Heishui River has been changed due to human activities such as hydropower station construction, overfishing and sand excavation from river channels. In order to assess the health state of Heishui River, 4 times fish resources surveys were conducted at 23 sampling sites in Heishui River from November 2018 to September 2019. Fish samples were collected by gill nets(outer mesh 7cm, inner mesh 2-3cm, net height 2m, net length 80m) and cages(12m × 0.4m × 0.4m). The data of species classification of all fish collected were determined at each sampling site. During the survey, a total of 45 fish species were identified including 4 orders, 10 families, and 33 genera. Three study sites were selected as reference sites, which were the Heishui River estuary, the upstream of the hydrometric station, and the 825 backwater point. Eight metrics were selected form 27 candidate metrics by distributing range analysis, discriminatory power analysis and Pearson’s correlation analysis to develop the final biotic integrity index of fish(F-IBI) evaluation system. The IBI value of each sampling site was then calculated using 1, 3, 5 assignment method and the ratio method to assess the health state of the Heishui River, and the status of river health was categorized into five levels: “no fish”, “very poor”, “poor”, “fair”and “healthy”. The result showed that although the result of the 1, 3, 5 assignment method and the ratio method is not exactly the same, the trend is consistent. The health status of most sampling points in Heishui River is at a "poor" and "fair" level. The Pearson correlation analysis showed that the IBI was significantly negatively correlated with altitude（P<0.01）. Abundance biomass comparison(ABC) curve showed that the fish community structure in Heishui River was moderately affected on the whole. The assessments were consistent with the actual situation in this river drainage, which can provide a scientific basis for the environmental protection and monitoring of the Heishui River.