梯级水利工程背景下嘉陵江鱼类群落功能多样性变化及主要影响因子

Rivers have provided a vast number of goods and services, however, this water ecosystem had been dramatically affected by anthropogenic activities, among which cascade water conservation projects are the most important factor to change the natural characteristics of river and to influence the functional diversity of fish communities in rivers. This project uses fish community of Jialing River to explore functional diversity variation and main effects of fish community in Jialing River under cascade water conservation projects, based on the comparison of modern and historical data of the fish community. To address this question, we will first collect data on the composition of fish community using different method and measure important environmental variables which might influence fish community structure. We will also identify functional groups for the fish community of the Jialing River, based on the morphological traits which are assumed related to trophic guild, habitat classification, physiological tolerance and body morphology. Functional Ecological Approaches will be used to explore the current state and dynamic development of fish community functional diversity; the spatial and temporal distribution patterns of fish community functional diversity along the altitudinal gradient; the main effects of fish functional diversity variation; and the important ecosystems, habitats and species for priority protection at the watershed scale, combined with the eco-region conservation methodology. Our results can not only give the original case study research for revealing variation of river fish community functional diversity and the main influence factors under cascade water conservation projects, and protecting river ecosystem and fish biodiversity, but also provide adaptive countermeasures for operation management of cascade water conservation projects.

河流既为人类提供了大量的生态功能产品，但也是受人类活动影响最为严重的生态系统之一。梯级水利工程是影响河流生态系统和鱼类群落功能多样性最为突出的一个因素。本项目以嘉陵江鱼类为研究对象，通过野外收集鱼类群落分布、环境因子和历史资料，选取与食性类型、生境类型、生理耐受性和游泳能力等相关的鱼类形态功能特征，将鱼类群落划分不同的功能类群，用功能生态学方法分析河流鱼类群落功能多样性的时空格局和动态变化，比较梯级水利工程开发前后鱼类群落功能多样性变化规律，厘清影响鱼类群落功能多样性变化的主要因子，并结合生态区生物多样性保护分析方法，从流域尺度上确定嘉陵江流域需要优先保护的生态系统、栖息地和物种。研究结果不仅能为揭示在梯级水利工程背景下河流鱼类群落功能多样性的变化规律及主要影响因子，保护河流生态系统和鱼类多样性提供原始资料和研究例证，也能为梯级水利工程今后的运行管理提供适应性对策建议。

河流生态系统是受人类活动影响最为严重的生态系统之一，本项目选择评价水环境健康状况和生物多样性最直接和最有效的鱼类为研究对象，通过调查了水环境变化后嘉陵江鱼类组成和鱼类群落现状，结合历史资料分析了梯级水利工程前后嘉陵江鱼类组成和群落的变动情况，分析了嘉陵江干流鱼类群落功能多样性的年度、季度和月份变化及主要影响因子。鱼类群落功能多样性通过MPDI（Mean Pair-wise Distance index）和NNDI（Standard Deviation of the Nearest Neighbor Distance index）来评估。结果发现：在年份变化中，MPDI在2014年最高，在2013年最低，且呈现明显的波动性；NNDI在2016年最高，从2013年到2015年逐渐降低；在季度变化中，MPDI在春季和夏季明显高于秋季和冬季，而NNDI则从春季到冬季，呈现逐渐增加的趋势；在月份变化中，较高的MPDI出现在6月至11月间，而NNDI则变化不大。嘉陵江干流鱼类群落多样性的动态变化可能与鱼类的摄食和繁殖密切相关。不同江段分析结果显示，嘉陵江鱼类群落功能多样性在下游合川段的MPDI值最高，从上游到下游有逐渐增加的趋势；而NNDI值在各江段呈现波动性变化；影响嘉陵江鱼类群落功能多样性的主要因子有水温、气温、透明度等，但在不同江段主要影响因子存在较大差异；另外，本项目研究过程中还对河流鱼类保护、鱼类标本制作方式等提出了针对性的建议。