The Diversity,Feeding Characteristics And Environment Assessment Of Fishes In The Yunnan Section Of Nujiang River

Nujiang river basin is very rich in the distribution of the species,is one of the world's biodiversity hotspots.Nujiang River is one of the main rivers in China,which has not yet been built the ydropower station in the main stream,and there are few other aspects of development.Therefore,it is called the original river.In today's increasingly tense energy,Nujiang River has attracted the attention of hydropower resources.The development of hydropower is bound to have a significant impact on the local ecological environment and biology,especially the impact on fish.Due to the unique biological diversity of Nujiang River,the issue of hydropower development in Nujiang River has attracted wide attention both at home and abroad.Therefore,the fish diversity,food composition and ecological environment of the main stream and 13 tributaries of the Yunnan section of Nujiang River were investigated in this study.Based on the biodiversity survey of dry tributaries and the comparison of the habitat similarity of dry tributaries,the Meng Baltic River was selected for discussion.The conclusions are drawn by this study:(1)A total of 1572 fish samples were obtained during field investigation,belonging to 3 orders,9 families,26 genera and 32 species.Cypriniformes was most species,21 species,accounting for 65.6% of the total;followed by Siluriforms,8 species,accounting for 25% of the total.A total of 1048 species were obtained from the main stream of Nujiang River,with a total of 29 species of fish,and a total of 524 species were obtained from the tributaries.In Gongshan section collected 7 fish species,accounting for 21.9% of the total.There were 7 species of fish in the section of the Gong Shan,6 species in the Fu Gong,12 in the Lujiang and 24 in the Baoshan.The fish are concentrated in the range of 500-900 m.The top three of the Yunnan section of Nu River fish index of relative importance was Placocheilus cryptonemus,Schizothorax nukiangensis,and Channa gachua.Channa gachua was downstream of dominant species.The results of diversity index showed that,except for Simpson dominance index,Pielou evenness index J,Alatalo evenness index Ea,the other indexes showed a trend of increasing from upstream to downstream.The structure of fish community in adjacent sections of the river was similar(2)The Yunnan section of Nujiang River fish food organisms survey results for phytoplankton,there were 6 doors and 35 genera and 57 species of planktonic animal were detected in 27 genera and 38 species of animal plankton,benthic animal were detected in 3 of 4 classes 12 orders and 46 species(genera),aquatic plants(wet)30 families,53 genera,73 species.12 kinds of fishes in the Yunnan section of Nu River were analyzed.The food,Schizothorax gongshanensis,Barbodes opisthoptera,Pseudorasbora parva,Tilapia mossambica and Garra orientalis clustered cluster analysis,Channa gachua and Tachysurus fulvidraco,Placocheilus cryptonemus,Triplophysa stenura and Schizothorax nukiangensis are clustered,Raiamas guttatus and Piatytropius sinensis together as a class.There were some differences in the amount of trophic niche breadth and the number of prey species among the 12 species,and the range of trophic niche breadth index was 0.073-0.744,with an average value of 0.282.The range of species number was 6-14 species,with an average of 8.75.12 kinds of fish,Pseudorasbora parva(0.073)and placocheilus cryptonemus(0.079)the niche breadth index is less than 0.1,the feeding habits of two species of fish is relatively narrow,tend to be relatively single-minded food feeding.There are 8 kinds of fish trophic niche width index between 0.1-0.4,respectively Garra orientalis(0.107),Schizothorax gongshanensis(0.159),Barbodes opisthoptera(0.171),Tachysurus fulvidraco(0.226),Schizothorax nukiangensis(0.189),Tilapia mossambica(0.313),Piatytropius sinensis(0.340),Triplophysa stenura(0.367).In general,the diversity of food and habitat resources in the Nu River waters resulted in a small niche overlap among the major fish species and a low food competition among species.Fish can choose the relative abundance of palatable diets to improve the utilization of food resources,reduce the competition among species,and finally maintain the stability of fish community structure.(3)The similarity of fish habitat between Nu River and the Meng Baltic River was compared.The similarity of the hydrological system was 0.385,and the similarity grade was generally similar.The similarity of water environment system was 0.468,and the similarity grade was Basic similarity.The similarity of river topography and geomorphology was 0.526,and the similarity grade was basically similar.The similarity between the Nujiang River and the Meng Paltic River was 0.458,and the similarity grade was generally similar.Their river habitats were similar,but their similarity was not high.(4)The fish habitats of the Meng Baltic River were seriously disturbed by human activities..Using plankton to evaluate the water quality of the Meng Baltic River,the results showed that except for a few stream segment,which were light pollution or non polluted water,the other stream segment were all polluted by alpha or beta water qualit,and no serious polluted river was found.The evaluation results of fish biointegrity in the Meng Baltic River were in general.