FISH COMMUNITY STRUCTURE AND ITS RELATIONSHIP WITH ENVIRONMENTAL FACTORS IN JUMA RIVER IN HAIHE RIVER BASIN

In order to understand the fish community structure in Juma River and its relationship with the environmental factors, 15 sampling stations in Juma River were surveyed in May, August and October, 2019, August and October, 2020 and May, 2021. A total of 37 fish were collected, belonging to 11 families and 5 orders. Cypriniformes were the most, accounting for 64.86% of the total species captured. Ecologically, the fish community in Juma River is dominated by demersal and omnivores species and there are fewer carnivorous fish. Compared with the historical data, the number of fish species has decreased. Index Relative Importance (IRI) shows that 10 species had IRI≥500, Carassius auratus, Pseudorasbora parva, Zacco platypus were the dominant species. C. auratus, P. parva and Micropercops swinhonis were collected in all seasons and all sampling sites. One-way analysis of variance (ANOVA) showed that the number of individuals (N), species (S), Shannon-Wiener diversity index (H') and Margalef richness index (D_Ma) of the fish community had significant differences between different seasons, Pielou evenness index (J') showed no significant differences. SNK multiple comparison test showed that the number of individuals and species was the highest in May 2019, Shannon-Wiener diversity index (H') and Margalef richness index (D_Ma) was the highest in August 2019. The numbers of individuals showed significant differences between different altitudes, an average of 143.91 fishes can be collected at sampling station above 500 meters and only 48.19 fishes can be collected at sampling station below 500 meters. Cluster analysis and Non-metric Multidimensional Scaling (NMDS) divides the source of the Juma River and the Diaojianghui into group Ⅰ, the Zijingguan Bridge and Qingliangjian into group Ⅱ, remaining sites are divided into group Ⅲ. The abundance biomass comparison curve (ABC) showed that the fish community was undisturbed only in August 2020 and was moderately disturbed in the remaining months. Redundancy analysis (RDA) showed that altitude, chlorophyll a, and temperature were the main environmental factors affecting the fish community in Juma River. Altitude is the environmental factor that greatestly affects the structure of fish communities in the Juma River, it has a great influence on Triplophysa cuneicephala, Triplophysa dalaica and Rhynchocypris oxycephalus. Chlorophyll a was highly correlated with the density of phytoplankton and it has a great influence on Micropercops swinhonis, Zacco platypus and other omnivorous fish.