小江回水区江段鱼类群落结构的时空变动及驱动因素分析

基于2013年和2019年5-7月以及10-11月在小江回水区江段开展的鱼类资源调查及生境数据收集，采用多元分析方法量化分析了小江回水区江段非生物因子时空变动与鱼类群落结构时空变动的关系，揭示了三峡水库正常蓄水运行后小江回水区江段鱼类群落结构的时空变动特征及其驱动因素。研究结果显示：2013年和2019年共在小江回水区江段采集到鱼类74种，隶属于7目15科56属，其中优势种鱼类15种，长江上游特有鱼类7种、外来鱼类5种；小江常年回水区的鱼类群落结构在2019年时发生了明显的改变，而小江变动回水区江段的鱼类群落结构在2013年和2019年间无明显差异；小江常年回水区江段的鱼类群落结构在2013年时显示明显的季节性变动特征，然而在2019年时季节性变动特征变得不明显；小江变动回水区江段的鱼类群落结构在2013年和2019年时均显示明显的季节性变动特征；总磷含量、磷酸盐含量、水温和流速显著影响着小江回水区江段鱼类群落结构的时空变动格局，其中磷酸盐含量和水温是驱动小江回水区江段鱼类群落结构变动的最关键的两个因素。研究结果表明：尽量维持小江变动回水区的自然生境特征、采取措施控制小江常年回水区外来物种的数量以及严格控制外源营养物的输入，对于保护小江回水区江段土著鱼类的资源具有重要的意义。

Spatiotemporal Variation of Fish Community Structure and Its Driving Factors in the Backwater Area of Xiaojiang River

Based on the fish resource survey and habitat data collection conducted in the sections of backwater area of Xiaojiang River from May to July in 2013 and from October to November in 2019, the relationship between the temporal and spatial changes of abiotic factors and the temporal and spatial changes of fish community structure is quantitatively analyzed using multivariate analysis methods, and in turn the temporal and spatial variation characteristics of fish community structure and its driving factors in the backwater area of Xiaojiang River after the normal storage and operation of the Three Gorges Reservoir are revealed. The results show that: a total of 74 fish species belonging to 7 orders, 15 families and 56 genera are collected from the backwater area of Xiaojiang River in 2013 and 2019, including 15 dominant species, 7 endemic species and 5 exotic species; the fish community structures in the perennial backwater area of Xiaojiang River has changed significantly in 2019, while no significant difference in the fish community structures in the river section of the variable backwater area of Xiaojiang River are observed between 2013 and 2019; the fish community structures in the perennial backwater area of Xiaojiang River show obvious seasonal variation characteristics in 2013, but the seasonal variation characteristics become less obvious in 2019; the fish community structures in the variable backwater area of Xiaojiang River show obvious seasonal variation characteristics in 2013 and 2019; total phosphorus content, phosphate content, water temperature and flow velocity significantly affect the temporal and spatial change pattern of fish community structures in the backwater area of Xiaojiang River; phosphate content and water temperature are the two key factors driving the change of fish community structures in the backwater area of Xiaojiang River. The results indicate that maintaining the natural habitat characteristics of the variable backwater area of Xiaojiang River, taking measures to control the population size of alien species in the perennial backwater area of the Xiaojiang River as well as strictly controlling the input of exogenous nutrients are of great significance to protect the indigenous fish resources in the backwater area of Xiaojiang River.