西藏河流裂腹鱼类分布格局及环境影响因素——以怒江和雅鲁藏布江为例

Distribution Pattern and Environmental Impact Factors of SchizothoracinaeFishes in the Rivers of Tibet: The Case of Nujiang River and Yalu Zangbo River

西藏因其独特而复杂多样的地形和气候条件,成为了中国生物多样性保护的重要区域。为探索环境因素对西藏河流裂腹鱼类分布的影响机制,2017年4月—2018年10月对西藏境内怒江和雅鲁藏布江的裂腹鱼类资源进行调查,并监测了主要的水体理化指标。鱼类资源调查结果表明,在怒江和雅鲁藏布江分别发现裂腹鱼4种、9种,两条河流分布的裂腹鱼种类各不相同。对裂腹鱼类与环境变量关系的冗余分析表明,怒江与裂腹鱼类分布有关的环境变量主要为水温(P<0.05,R2=0.1981)和流速(P<0.01,R2=0.3636),雅鲁藏布江与裂腹鱼类分布有关的环境变量主要为海拔(P<0.01,R2=0.7605)、水温(P<0.01,R2=0.2746)、Chla浓度(P<0.05,R2=0.2365),影响西藏裂腹鱼类分布的环境变量主要包括水温、流速、海拔和叶绿素a浓度。怒江裂腹鱼类的分布主要与水温、流速相关。雅鲁藏布江的裂腹鱼类的分布与水温、叶绿素a及海拔相关。裂腹鱼类的分布与水温呈现显著的相关关系。裂腹鱼类多样性指数与海拔的线性回归分析表明,裂腹鱼类物种丰富度随着海拔的上升呈现先增加后减少的趋势,在3700—3900 m海拔范围内裂腹鱼种类丰度最高。不同属的物种在西藏的分布海拔有一定差异,裂腹鱼属、叶须鱼属和裸裂尻属鱼类主要分布在1700 m以上海拔;尖裸鲤属分布在3700 m以上;裸鲤属分布在4600 m以上。研究结果对西藏的裂腹鱼类资源保护及种群恢复具有重要意义,可为西藏河流水生生物多样性保护及管理决策提供理论支撑。

Tibet has become an important area of biodiversity conservation in China because of its unique and complex topography and climate conditions.In order to explore the effect of environmental factors on the distribution of Schizothoracinae fish in Tibet,fishery resources were investigated and the main physical and chemical indexes were monitored from April 2017 to October 2018 in Nujiang River and Yalu Zangbo River in Tibet.Based on the survey results of fishery resources,a total of 4 species and 9 species of Schizothoracina fishes were found in Nujiang River and Yalu Zangbo River,respectively.The species distributed in the two rivers were different.Redundancy analysis on the relationship between the species and environmental variables showed that water temperature(P<0.05,R2=0.1981)and water velocity(P<0.01,R2=0.3636)were the main environmental factors related tofish distribution in Nujiang River,and altitude(P<0.01,R2=0.7605),water temperature(P<0.01,R2=0.2746)and chlorophyll-a concentration(P<0.05,R2=0.2365)in Yalu Zangbo River.Generally,the main environmental variables affecting the distribution of fissure fishes in Tibet included water temperature,water velocity,altitude and chlorophyll-a concentration.The distribution of Schizothoracina fishes had a significant correlation with water temperature.Linear regression analysis between the diversity index of Schizothoracinae fishes and altitude showed that the species diversity of Schizothoracinae fishes had a trend of increase at first and then decline with the elevation of altitude in the rivers of Tibet,and the species richness was the highest at the range of 3700‒3900 m altitude.The investigation revealed differences in the altitude range of fish distribution among different genera.The species of Schizothorax,Ptychobarbus and Schizopygopsis mainly distribute above 1700 m altitude,the species of Osygymnocypris above 3700 m altitude,and the species of Gymmocypris above 4600 m altitude,respectively.Research conclusions of this study are of great significance to resource protection and population restoration of Schizothoracinae fishes in Tibet,and can provide theoretical support for the conservation and management of aquatic biodiversity in the rivers of Tibet.