着生藻类和浮游藻类在三峡库区河流健康评价中的适宜性比较研究

藻类对水体环境变化敏感,其种类和数量与环境因素有密切联系并因环境的变化而发生变化,因此藻类常作为河流健康评价的指示生物。水体中的藻类根据生活习性不同分为着生藻类和浮游藻类,在河流健康评价中,以往的工作中有的采用浮游藻类用于河流健康评价,有的采用着生藻类用于评价,但浮游藻类和着生藻类究竟何者用于河流健康评价更适宜,抑或是二者在用于评价的适宜性上没有明显差别,迄今为止未开展过深入研究。选择三峡库区内的两条河流嘉陵江和乌江作为研究对象,于2015年9月,在两条河流上共布设11个研究断面,对嘉陵江、乌江的水环境理化因子、着生藻类和浮游藻类群落进行调查研究,应用着生藻类生物完整性指数(Periphytic algal index of biological integrity,Pe-IBI)和浮游藻类生物完整性指数(Phytoplankton index of biological integrity,Ph-IBI),并结合水体综合污染指数(Comprehensive pollution index,CPI),对嘉陵江、乌江的健康状况进行评价。研究结果表明,采用着生藻类生物完整性评价(Pe-IBI)能筛选出7个核心生物参数(藻类总分类单元数、蓝藻总分类单元数、绿藻总分类单元数、菱形藻比例、优势分类单元比例、香农多样性指数、均匀度)用于河流健康评价,着生藻类生物完整性指数(Pe-IBI)与水体综合污染指数(CPI)具有极显著的负相关关系,并且与水体中总氮、铅含量也有极显著的负相关关系,表明水环境质量越低则着生藻类的生物完整性越差;当采用浮游藻类生物完整性(Ph-IBI)用于河流健康评价时却只能筛选出1个核心生物参数(藻类密度),而且浮游藻类生物完整性指数(Ph-IBI)与水体综合污染指数(CPI)及12个水体环境指标并无明显的相关性。本研究表明,在河流水体中,与浮游藻类相比,着生藻类更能反映水体环境的状况,对河流水体环境的反映更为准确。因此,在以流动水体为特征的河流的健康评价中,采用着生藻类比采用浮游藻类更为适宜。

Comparative study on the suitability of periphytic algae and phytoplankton in river health assessment

Algae are sensitive to the changes of water environment. The species composition and individual quantity of algae are closely related to the living environments and change with environmental variation. Therefore, algae are usually used as an indicator to assess river health. Aquatic algae can be divided into periphytic algae and phytoplankton according to their inhabiting behaviors. In previous studies, some researchers applied phytoplankton in river health assessment, but some other researchers applied periphytic algae in river health assessment. However, as regards which of periphytic algae and phytoplankton is more suitable in river health assessment, or whether no significant difference exists in the suitability of periphytic algae and phytoplankton in river health assessment, very few studies have been reported so far. In this study, taking Jialing River and Wujiang River as the subject, 11 sections in total were set in these two rivers, and the physi-chemical characteristics of water environment and the periphytic algal and phytoplankton communities at 11 sections were investigated in September, 2015. By using periphytic algal index of biological integrity (Pe-IBI) and phytoplankton index of biological integrity (Ph-IBI), together with comprehensive pollution index (CPI), the health status of Jialing River and Wujiang River were assessed. It was shown in this study that seven core parameters including total algal taxa number, Cyanophyta taxa number, Chlorophyta taxa number, individual proportion of Nitzschia, individual proportion of dominant taxa, Shannon-Wiener''s diversity index, and evenness index, could be screened when the Pe-IBI was applied in the health assessment of Jialing River and Wujiang River. The negative correlations of Pe-IBI to CPI, total nitrogen content, and lead content of river water were found, which means that the biological integrity of periphytic algae decreased with the deterioration of water environment. However, when the Ph-IBI was applied in the health assessment of Jialing River and Wujiang River, only one core parameter (algae density) could be screened. Moreover, no correlation of Ph-IBI to comprehensive pollution index or to any of twelve water environmental factors was found. Our study revealed that, for rivers, periphytic algae is better than phytoplankton to indicate the water environmental quality, and consequently, periphytic algae is more suitable than phytoplankton to be used in river health assessment.