Fish diversity and resource status in the yangxian section of the hanjiang river under the context of inter-basin water transfer

Abstract

Aims: The Hanjiang River is an important water source of the Middle Route Scheme of South-North Water Diversion Project and Hanjiang to Weihe River Inter-basin Water Transfer Project. It is necessary to understand the current status and changes of fish species diversity for future conservation of aquatic ecosystem. Methods: In order to investigate the fish diversity and resource status in Yangxian section of the Hanjiang River, we surveyed the fish diversity of main stream and six tributaries twice from 2016 to 2017. The indices of Margalef, Shannon-Wiener, Pielou’s, and Jaccard were used to evaluate the main streams and branches in Yangxian County. The index of relative importance (IRI) was calculated to determine the dominant species, and the abundance biomass comparison (ABC) was used to analyze the interference to fish. Results: With historical data, our survey showed that this section of the river has 76 native species belonging to 57 genera, 14 families, and 6 orders. Fishes from Cyprinidae and Bagridae are dominant, accounting for 57.89% and 11.84% of the total number of native species, respectively. There are five endangered species, and three of them are classified as National Protected Wild Animals in China. The results of fish diversity analysis showed that the richness index and diversity index of the main stream of the Hanjiang River were significantly higher than those of the six tributaries. IRI index showed that the dominant species was Zacco platypus. An analysis of the ABC curve indicated that the fish community has been seriously disturbed. Conclusion: Water conservancy and hydropower projects are the main influences that were correlated with a decrease of fish diversity and populations. The construction of large dams on the main stream will change the habitat from flowing water to still water, and disrupt the connection between upper and lower streams, and cause the disappearance of spawning grounds. Small-sized hydropower stations on the river branches will reduce the water of downstream affecting the fish populations. The inter-basin water transfer project has the potential possibility to introduce fish species from different river systems. Our study provides basic data for the dynamic monitoring of fish diversity and an early warning of invasive species during the construction of the Hanjiang to Weihe River Water Diversion Project.