Fish Species Diversity And Assessment Index System For River’s Health In The Upper Reach Of Lijiang River

Species diversity of fish was investigated in the upper streams of Lijiang River, including four tributaries such as Xiaorong River, Chuan River, Ludong River and Huangbai River from April 2013 to January 2014. Which is to study the fish species composition, and the temporal variation of fish species diversity. To explore the characteristics of temporal and spatial variation of fish community composition and the relationship between the environmental factors such as dissolved oxygen, water temperature and the velocity etc. And establishment of biological integrity based on fish to assess the river health were studied in the upper reach of Lijiang River, aiming to protect fish resources in the upper reach of Lijiang River and enhance the basic research of River health assessment. The main results of this study were as follows:1. A total of 72 freshwater fish species(9508 individuals) belonging to 4 orders, 15 families and 51 genera were found in the upper reach of Lijiang River, they could be divided into Cypriniformes, Siluriformes, Synbranchiformes and Perciformes. The most species-rich orders were Cypriniformes(3 families, 45 species), which accounted for 62.50% of the total species, Siluriformes(5 families, 13 species) and Perciformes(6 families, 13 species), which accounted for 18.06% of the total species, Synbranchiformes(1 families, 1 species), which accounted for 1.39% of the total species.2. Among these 72 fish species were 22 species endemic to China, and 1 endemic species in Guangxi Province(Parabotia lijiangensis), 2 vulnerable species(Onychostoma lini, Siniperca undulate), 1 Newly record species in Guangxi Province(Aphyocypris chinensis). The dominant species were Zacco platypus(2544 individuals), Pseudogastromyzon fangi(1133 individuals) and Opsariichthys bidens(998 individuals). These 3 species comprised 49.17% of the total catch.The majority of fish species was stream fish in this watershed. Benthic fishes species were the most, accounting for 47.22%, followed by lower fish, accounting for 38.89%. Accounting for 37.50% of the total species were omnivorous fish species.3. The fish diversity changed significantly and results of species diversity showed that fish diversity such as Margalef index(Dma), the Shannon-Wiener species diversity index(He’), and the Pielou evenness index(Je) in Summer were higher than those in Spring and Winter, 7.59, 2.98, 0.72 respectively, while He’ and Je were the lowest in Autumn, 2.14 and 0.59 respectively. The diversity of the main stream of Lijiang River was higher than other four tributaries such as Xiaorong River, Chuan River, Ludong River and Huangbai River, while Simpson index(λ) was the largest in Huangbai River and its dominant species was the most obvious.4. Non-metric Multidimensional Scalings ordination(NMDS) was applied to compare fish communities in the upper reach of Lijiang River. The results showed that there was little apparent change associated with the seasons, the fish communities were differed between each sampling site. Difference of stream characteristics was likely to be caused by anthropogenic activities like human settlements, agriculture activities and engineering construction, which would result in variation of fish communities. There was a close relationship between diversity index and environmental factors such as dissolved oxygen, water temperature, pH, river width and depth. The fish species was significantly positively related to pH, water temperature, river width and depth, while being significantly negative correlation to dissolved oxygen. Canonical Correspondence Analysis(CCA) ordination with the stepwise selection method revealed that 8 of the 9 environmental variables significantly correlated to the fish communities such as altitude, distance from the convergence of each tributary, stream width, water temperature, dissolved oxygen, pH, water depth and sediment particle size. Meanwhile, fish communities at different sites were associated with different environmental variables in different seasons.5. Five metrics including species richness(M1), Shannon-Wiener diversity index(M7), middle and lower fish number percentage(M11), carnivorous fish number percentage(M14), toleranted fish number percentage(M22) from twenty two candidate metrics, were evaluated stepwise by distributing range analysis, discriminatory power analysis and Pearson’s correlation analysis. The traditional step method was used to calculate the value of each metric and IBI, and the status of river health was categorized into five levels, such as “healthy(IBI score>40) ”, “fair(IBI score=27-40) ”, “poor(IBI score=13-27) ”, “very poor(IBI <13) ” and “no fish”. The results showed that there were 10 sites for healthy, 8 sites for fair and 4 sites for fair. The river’s health of Xiaorong River, Chuan River and Ludong River were mainly at the status of “healthy” and “fair”, but “poor” in Huangbai River. The Pearson’s correlation analysis showed that the IBI was significantly positive correlated with dissolved oxygen.