赣东北信江水系淡水鱼类时空变化及其与环境因子之间的关系

The Xin-Jiang, the second largest river in Jiangxi Province, is a tributary flowing into the Poyang Lake system connected to the Yangtze River basin. It, with a high diversity of freshwater fish species and an uniqueness of faunistic component, is a key area of zoogeographic division in China. It is also important area of freshwater fisheries in Jiangxi Province. Unfortunately, the fish diversity of this river is still not well understood, and little is known about the community structure of its fauna. This project will try to conduct a field fish survey into this river, with the aim to have a better understanding of its fish fauna and fishery resource. Comparison of the database of this survey will be made with historical record to unveil the tend of the shift in the species composition of this river during the past 20 or more years,and then illuminate the degree to which the the global climate and human activities have impacts on this shift. This will provide intellectual support for biodiversity conservation and water resources management of the river. The project also attempts to investigate the fish community structure of this river and its relationship environmental factors in order to determine main factors affecting freshwater fish distribution in this river. Based on these results, possible impacts on the fish fauna caused by construction of hydroelectric dam across the river will be predicted, and the conservation measure used to mitigate the adverse influence will be provided.Moreover, the fish-based IBI is used to assess the aquatic ecological health of this river in order to provide basic information for managemant of water resource.

信江是江西省的第二大河流。作为鄱阳湖的重要支流，信江有着丰富的鱼类物种多样性及独特的区系组成，是中国动物地理区划中的关键区域。信江还是江西省重要的淡水渔业产区。然而，信江水系鱼类物种多样性仍存在较大的问题，其群落结构的研究尚未见相关报道。本项目拟通过对信江鱼类的调查，明确其鱼类区系组成及渔业资源。在此基础上，结合二十世纪90年代初期的鱼类区系调查资料, 分析信江鱼类多样性与群落结构的演变趋势，探讨全球气候变化和人类活动的影响程度，为水环境保护和水资源管理提供智力支持；同时，根据采样调查的鱼类和河流环境因子分析鱼类群落与环境因子的相互关系，揭示影响鱼类分布的主要环境因子，预测水利水电开发对信江鱼类区系结构的影响，提出保护措施；此外，采用鱼类生物完整性指数(F-IBI)来评价信江水生态健康，为信江水资源的管理提供科学依据。

信江是集防洪、供水、航运为一体大型河流，也是重要的淡水渔业产区。本项目对信江鱼类资源结构特点研究,可为信江乃至整个鄱阳湖鱼类资源管理及多样性保护提供依据。主要研究结果如下：1、共获得鱼类标本38262尾，经鉴定隶属6目18科63属98种，以鲤形目为主，计3科44属69种，占物种数的70.4%；2、98种鱼类可划分归6个区系复合体,以江河平原复合体为主；3、从食性类型来看,肉食性鱼类所占比例最大,其次为杂食性鱼类；从生态类型来看，湖泊定居性鱼类所占比例最大，其次为山溪河流性鱼类；4、从空间分布上看，信江鱼类从上游至下游，数量逐渐增多，并呈现明显的山区-平原鱼类空间格局；5、相对重要性指数分析显示，子陵吻虾虎和点纹银鮈为优势种; 鲫鱼、麦穗鱼和棒花鱼等8种为相对优势种，均为中小型鱼类。与历史记录相比，未见鳗鲡目、鲑形目、颌针鱼目、鲀形目等4目种类，鲱形目的鲱科、鲤形目的胭脂鱼科均未捕获。就种类而言，鲤形目鱼类减少最多。此外，还记录到几种以前未报道的新记录种，如鳉形目胎鳉科的食蚊鱼、鲈形目太阳鱼科的太阳鱼及加州鲈、鲇形目鮰科的斑点叉尾鮰、鲿科的长须黄颡鱼和光泽黄颡鱼，其中食蚊鱼、太阳鱼、加州鲈和斑点叉尾鮰均为外来物种，需加强监控。另外，通过鱼类完整性指数(F-IBI)来评价信江流域生态系统的健康状态，结果显示，信江水系从上游到下游的鱼类群落完整性均处于较好到一般的水平，总体情况较好，但也面临一定压力。