| In July,August,November and December 2018,the community structure and diversity of fish communities in Nanshan area of Chengbu County were investigated by using the sample collection method.3068 fish samples were collected,with a total weight of 26484.9g.A total of 33 species of fish were recorded,including 3 orders,10 families,26 genera,among which the number and weight of the fish in Cyprinidae was the highest,with 14 species,accounting for 42.42% of the total species and83.76% of the total weight.Compared with the national freshwater fishes,the species,orders and families of fishes in Nanshan area account for3.14%,16.67% and 19.23%,respectively.Collected 33 species of fish,there are 20 different endemic to China,otherwise the Liobagrus marginatus listed in the "China species red list" specified in the vulnerable.In Nanshan Chengbu area ecological type of fish is given priority to with stream type,omnivorous,bottom water fish,dominant species is small fish and render more young individual phenomenon,dominance in the top five for the Onychostoma barbata,Acrossocheilus parallens,Coreoperca whiteheadi,Vanmanenia pingchowensis,Hemibarbus maculates,Onychostoma barbata is whether quantity or weight are accounted for the biggest,it is composed of four age groups,mainly(including 0 age group)the age of 1 year,accounting for 80.52%.Acrossocheilus parallens was composed of three age groups,with the age of 1(including 0)as the main group,accounting for 92.31%.The composition of fish fauna shows a typical state of cross-regional integration,especially in south China and east China.Thirty-three species of fish make up eleven types.The composition of east China and south China was significantly higher,accounting for 24.24%.The second species were east China and endemic species,which accounted for15.15% respectively.The composition of south China and north-east-south China accounted for 12.12%,west-east China accounted for6.06%,and the other five types accounted for 3.03%.From the separation,it can be concluded that east China has the highest proportion of weight,which is 33.33%.In south China,29.63% were followed.The northern region was the third,accounting for 14.81 percent.Huaxi district and ningmeng district accounted for 13.58 percent and 8.64 percent.The diversity index,evenness index and richness index of this area are 2.283,0.653 and 3.986,respectively.Compared with Yunshan forest park in Wugang city,Dupangling in Yongzhou city,Qingshitan in Guangxi Province and other adjacent protected areas,both species number and diversity coefficient of Chengbu Nanshan area are at a high level,with only low evenness.The diversity index level of pingshui tributaries in the two tributaries in the study area was significantly higher than that of the bounded backwater tributaries.The G-F index was 0.414,which was similar to the level of Duanchengjiang wetland park in Guangxi province,and lower than the level of the entire Yuanjiang river basin.The level of pingshui tributaries in the two tributaries in the region was at a high level.In terms of growth characteristics,it is obvious that small individuals dominate.Among the 33 species of fish,22 species with an average weight of less than 10 g were collected,accounting for 66.67% of the total species.Among the 8 species of 2583 major fish specimens measured,most species were small and light individuals,but the relationship between body length and weight presented a positive power function correlation.Except that Phoxinus oxycephalus and Carassius auratus belonged to strong allometric growth,most of them showed uniform or nearly uniform growth.Measurement of 8 kinds of main fish relative fantness range in 1.650 ~ 13.012,the variation is larger,the highest for Carassius auratus,the lowest for Hemiculter leucisculus,more than the rest of the range from 2.0 to 4.0. |
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