Spatiotemporal Changes Of Fish Community Structure And Diversity In Baiyangdian Basin

Baiyangdian Basin is located in the central part of Daqing River system in the Hai River Basin.There are nine rivers into the upstream of the lake,the downstream through the Zhaowangxin River,Hai River into the Bohai Sea.There are abundant wildlife resources in this area.The investigation of fish resources in Baiyangdian from the 1950s to 2009 mainly focused on the composition of fish species,and the survey area only included Baiyangdian District.Based on a systematic survey of fish resources in the Baiyangdian Basin from 2018to 2020,this paper analyzed the spatial and temporal changes of fish species composition,ecological types,fish community diversity,fish functional group division,and the relationship between fish community and environmental factors.The main research results are as follows:（1）A total of 39129 fish,belonging to 54 species,15 families and 6 orders,were collected in Baiyangdian basin,with 36 species as 2 family of Cypriniformes,9 species as 6family of Percifoemes,4 species as 2 family of Siluriformes,2 species as 2 family of Symbranchiformes,2 species as 2 family of Osmeriformes,1 species as 1 family of Beloniformes.According to the ecological types,the most species is sendentary fish were 25species accounting for 46.30%;Based on feeding habies,omnivorous fish is the largest number of species,were 36 species accounting for 66.67%;According to the classification of ecological niche,there were 10 species of pelagic fishes,22 species of middle and lower fishes and 22 species of demersal fish;Divided by spawning type,the fish of drifting ovalfish is the largest number of species,were 24 species accounting for 44.44%.The dominant species in the Baiyangdian basin are Carassius auratus,Hemiculter leucisculus,Chanodichsthys,Pseudorasbora parva,Zacco platypus,Misgurnus anguillicaudatus,Micropercops swinhonis,Pelteobagrus fulvidraco,Gnathopogon mantschuricus,Gnathopogon mantschuricus,Gnathopogon mantschuricus,Gnathopogon mantschuricus,Rhinogobius similis.The dominant species of fishes had some differences in different regions.（2）The fish diversity indiex were significantly changed with season and region（P<0.05）.In the analysis of seasonal variation,the number of fish individuals,species,Shannon-Wiener diversity index（H’）and Margalef richness index(D_Ma)in spring were significantly higher than in summer and autumn,among which autumn was the lowest.Pielou evenness index（J’）in spring,autumn and summer had significant differences,which were all higher than summer.In the analysis of different regional The number of fish individuals in Baiyangdian was the highest,followed by Sha River and Juma River,which were significantly higher than the Xidayang Reservoir,Wangkuai Reservoirs,Fu River and Xiaoyi River.Baiyangdian had the most species,followed by Juma River and Sha River,which were significantly higher than the Xidayang Reservoir,Wangkuai Reservoirs,Fu River and Xiaoyi River.The Shannon-Wiener diversity index（H’）of Baiyangdian and Juma River was significantly higher than that of other regions,but there was no significant difference in Fu River,Xiaoyi River and Wangkuai Reservoir,and the Xidayang Reservoir was the lowest.Pielou evenness index（J’）was the lowest in the Xidayang Reservoir,other regions had no significant difference.The Mardalef index(D_Ma)was the highest in Baiyangdian and Juma River,followed by Sha River,Fu River,Xiaoyi River and Wangkuai Reservoir,and the lowest in Xidayang Reservoir.（3）Non-metric multi-dimensional scaling（NMS）analysis showed that there was no obvious separation of species composition pattern between seasons in Baiyangdian Basin,but there was obvious separation of species composition pattern between different regions,and some regions overlaps.The results of CLUSTER analysis showed that when the similarity coefficient was 86.53%,the fishes in Baiyangdian Basin were divided into three feeding function groups,FG1,FG2 and FG3,which were mainly determined by mouth height/mouth width.The similarity coefficient was 90.58%,and it was divided into 6 locomotion function groups.Among them,LG1,LG2 and LG4 were mainly determined by body height/body length,and LG3a,LG3b and LG3c were mainly determined by maximum caudal fin height/minimum caudal peduncle height.（4）The canonical correspondence analysis（CCA）sequence diagram showed that the main environmental factors causing the spatial structure differences of fish in Baiyangdian Basin were altitude,DO,water temperature,transparency,turbidity.Most of species such as Triplophysa,Rhynchocypris oxycephalus,Rhynchocypris lagowskii,Gnathopogon mantschuricus,Microphysogobio hsinglungshanensis,Zacco platypus,Opsariichthys bidens live at high altitude and high DO regions.Rhinogobius similis,Rhodeus sinensis,Rhodeus ocellatus are live in the high transparency regions.Carassius auratus,Hemiculter leucisculus,Chanodichsthys erythropterus,Culter alburnus were positively correlated with water temperature.Misgurnus anguillicaudatus,Paramisgurnus dabryanus were positively correlated with turbidity.