漓江流域基于鱼类生物完整性评价河流健康指标体系的研究

Lijiang River in the Guangxi Province which inflows into the Pearl River, is known around the world due to its beautiful scenery and clean water, and its total length is 214 km. The ecological environment is threatened by numerous threats such as seasonal lack of water. Thus, the conservation and restoration for ecosystem of Lijiang River was listed as the first pilot scheme by the Ministry of Water Resources of the People's Republic of China, which aim to protect continuous flow and water satisfied for water standards in the Lijiang River, and to recover biodiversity and habitat of Lijiang River. Traditional assessment of river's health is mainly from its physical and chemical index of water, however, even if water quality is satisfied for water standards, it does not mean that the river is healthy. More and more scholars believe that integrity of ecosystem and biological species is the fundamental elements for river's health and its sustainable development. Therefore, temporal and spatial variation of fish communities and their association to environmental variables will be studied in this project, and index of biological integrity based on fish will be established by means of index selection based on the theory of river's health assessed by index of biological integrity (IBI), which is applicable to Lijiang River. Based on this, variations of fish resources and diversity before and after the construction of four water conservancy projects will be compared, and river's health will be assessed. Implementation of this project could provide scientific evidences for assessment of river's health and conservation of fish diversity, and provide theoretical guidance for watershed management, comprehensive exploitation and utilization of resources, and conservation of aquatic environment in the Lijiang River.

广西漓江属珠江水系，全长214km，因风景秀美，水质清澈而闻名世界。季节性缺水等原因导致漓江生态环境面临严重的威胁，漓江生态系统保护与修复被水利部列为全国第一批试点单位，保证漓江不断流、水质不超标、生物多样性和生物栖息地得到恢复是亟待解决的重要课题。传统的河流健康评价主要从水质理化指标上去衡量，但是即使水质达标，也并不意味着河流健康。目前国内外更多学者认为，生物物种和生态系统完整性才是河流健康并可持续的根本要素。本项目主要基于生物完整性（IBI）评价河流生态系统健康的原理，研究鱼类群落结构的时空变化格局及其与环境因子的关系，并通过指标筛选建立适合漓江的鱼类生物完整性（FIBI）评价指标体系；在此基础上，比较上游四个水利工程建设前后的鱼类资源及其多样性变化，并对河流健康进行评价。项目将为河流健康评价及鱼类多样性保护提供科学依据，并为漓江流域的资源管理、综合开发利用及水环境保护提供理论支持。

本项目对漓江流域的鱼类进行大量实地采样调研，研究发现漓江现存鱼类91种，隶属于5目17科65属。其中易濒危物种有2种（波纹鳜、小口白甲鱼），广西新记录物种1种（中华细鲫）；漓江鱼类群落结构空间分布差异显著，不存在季节性差异。会仙湿地鱼类有35种，隶属于5目13科31属，该水域的鱼类季节性差异较显著，如春季优势种为鲫和子陵吻虾虎鱼，夏季为高体鳑鲏和叉尾斗鱼，秋季为鲫，冬季为鲫和短须鱊。本研究比较研究了漓江上游3个新建水库（小溶江水库、斧子口水库和川江水库）和已成的青狮潭水库的鱼类群落组成，研究发现水库建设之前鱼类群落的优势种主要为溪流型鱼类，如宽鳍鱲、方氏品唇鳅和马口鱼。而青狮潭水库鱼类以湖泊型鱼类为主，其优势种为鲫、䱗和鲤。基于漓江上游区和中下游鱼类种类组成呈空间分布差异，本项目针对漓江上游和中下游分别建立了鱼类生物完整性评价体系。漓江上游鱼类IBI指标体系有5个指标，分别是鱼类总物种数、Shannon-Wiener多样性指数、中下层鱼类占总类数的百分比、肉食性鱼类数量百分比、耐受性鱼类占总鱼类数的百分比。研究发现小溶江、川江、陆洞河大部分河段处于“健康”或“一般”，而黄柏江则为“较差”。漓江中下游IBI指标体系有7个指标，分别为鱼类总物种数、鲤科鱼类占总类数的百分比、鮈亚科鱼类种数、鮊亚科鱼类种数、杂食性鱼类占总类数的百分比、敏感性鱼类占总类数的百分比、耐受性鱼类占总类数的百分比。漓江中下游河段处于一般或一般以上水平，未出现较差的河段。.此外，本项目还研究了漓江中下游仔稚鱼群落结构，主要优势种为高体鳑鲏、宽鳍鱲、䱗、食蚊鱼和广西鱊。分析推测出该河段鱼类的繁殖期主要集中在4-7月。因此建议，漓江流域的禁渔期由原来的每年4月1日至6月1日延长到4月1日至7月1日。本项目的研究成果可为河流健康评价及鱼类多样性保护提供科学依据，并为漓江流域的资源管理、综合开发利用及水环境保护提供理论支持。