三峡库区鱼类群落结构和功能多样性

Community structure and functional diversity of fishes in the Three Gorges Reservoir

物种的功能特征是联系群落结构和功能的关键因素,开展功能多样性研究可以更好地理解群落结构和功能的关系。为了解三峡库区鱼类群落结构和功能多样性的空间格局,作者于2019年和2020年对三峡库区库首秭归、库中云阳、库尾巴南及库首支流香溪河下游峡口、库中支流小江下游高阳、库尾支流嘉陵江下游合川等江段的鱼类进行调查,分析了鱼类群落结构和多样性,从摄食、运动和繁殖3个方面探讨了鱼类功能多样性空间格局。在三峡库区及主要支流共采集到鱼类78种,隶属于6目15科56属。各江段以广适性和静水性鱼类为主,其中库首秭归和支流香溪河下游峡口、小江下游高阳江段的短颌鲚(Coilia brachygnathus)和贝氏?(Hemiculter bleekeri)等静水性鱼类相对丰度较高,库中云阳、库尾巴南和支流嘉陵江下游合川江段的蛇鮈(Saurogobio dabryi)和光泽黄颡鱼(Pelteobagrus nitidus)等广适性鱼类相对丰度较高。非度量多维尺度(non-metric multidimensional scale,NMDS)和Bray-Curtis相异性指数分析表明,秭归和嘉陵江下游合川江段群落结构差异最大,香溪河下游峡口和小江下游高阳江段群落最为相似。Margalef丰富度指数(D)、Shannon多样性指数(H’)和Pielou均匀度指数(E)在干流江段为:秭归<云阳<巴南,支流江段为:嘉陵下游合川<小江下游高阳<香溪河下游峡口。鱼类摄食、运动和繁殖相关的功能多样性在空间上的变化趋势较为一致,库首秭归江段的功能多样性最高,嘉陵江合川江段的功能多样性最低。总功能多样性和物种多样性变化趋势一致,在干流江段为:秭归<云阳<巴南,在支流江段为:嘉陵下游合川<小江下游高阳<香溪河下游峡口。研究结果可为三峡库区鱼类多样性保护和管理提供科学依据,为长江“十年禁渔”效果评估提供本底资料。

Aims:The functional characteristics of species are the key factors linking community structure and function.Studies on functional diversity seeks to understand the important relationship between community structure and function.The Three Gorges Dam is currently the world’s largest hydropower project.The dam’s construction blocked fish migration,altered river habitats,and dramatically changed fish species and distribution.Our study contributes to understanding of the spatial pattern of fish community structure and diversity after the impoundment of the Three Gorges Reservoir and clarifies the relationship between species diversity and functional diversity.Methods:In order to explore the spatial pattern of fish community structure and functional diversity,field investigations were conducted in the main stream and tributaries of the Three Gorges Reservoir area from 2019 to 2020.The main stream includes Zigui,Yunyang and Banan which are located in the upper,middle and lower reaches of the reservoir,respectively.The tributaries contain Xiakou(downstream of Xiangxi River),Gaoyang(downstream of Xiaojiang River)and Hechuan(downstream of Jialing River).They are located at the head,middle and end of the reservoir,respectively.We analyzed the structure and diversity of fish communities and explored the spatial patterns of functional diversity of fish by three characteristics:food acquisition,locomotion and reproduction.Results:A total of 78 species belonging to 6 orders,15 families and 56 genera were collected in the Three Gorges Reservoir.Eurytopic and limnophilic fish species dominated the reservoir.The limnophilic species,such as Coilia brachygnathus and Hemiculter bleekeri,had higher relative abundance in the Zigui,Xiakou and Gaoyang sections.In Yunyang,Banan and Hechuan river sections,the relative abundances of eurytopic species such as Saurogobio dabryi and Pelteobagrus nitidus were high.Non-metric multidimensional scales(NMDS)and Bray-Curtis dissimilarity index analyses indicated that differences in fish community structure were greatest between Hechuan and Zigui,and most similar between Xiakou and Gaoyang.Margalef richness index(D),Shannon diversity index(H’)and Pielou evenness index(E)gradually increased from Zigui,through Yunyang to Banan in the main stream of the reservoir.In the tributaries,species diversity was highest in Xiakou,with lower diversity in Gaoyang and lowest in Hechuan.The spatial variation of functional diversity related to fish food acquisition,locomotion and reproduction were relatively consistent throughout the study area.The highest value was observed in Zigui and lowest in Hechuan.The total functional diversity had a consistent spatial variation with community species diversity in the Three Gorges Reservoir.The diversity indices gradually increased in the main stream from Zigui to Banan.In the tributaries,diversity indices were the highest in Xiakou,followed by Gaoyang and Hechuan.Conclusion:Overall,there are evident spatial differences in fish community structure and diversity in the Three Gorges Reservoir area.Functional diversity is more sensitive than species diversity to changes in fish community.