Analysis of fish diversity in Yuqiao Reservoir based on morphological identification and eDNA technology

Abstract

[Objective] To clarify the current status of fish diversity in Yuqiao Reservoir, compare the application effectiveness of morphological identification and environmental DNA(eDNA) technology in fish resource surveys, and provide data support for protection of the reservoir's water ecological environment. [Methods] From 2022 to 2023, fish were collected using three-layer gillnets and ground cages at five sampling sites, followed by morphological identification. Dominant species were analyzed using the Pinkas index of relative importance, and interspecific relationships were analyzed using niche breadth and overlap models. From May to October 2023, eDNA samples were collected synchronously at each sampling site. PCR amplification and highthroughput sequencing were performed based on 12 S r DNA gene primers, species annotation was completed, and community characteristics were analyzed using α-diversity indices. [Results] A total of 24 fish species were captured through morphological identification, belonging to 5 orders, 10 families, and 23 genera. Cypriniformes accounted for 66. 67%. Six dominant species, including Cyprinus carpio and Rhinogobius giurinus, accounted for 72. 34% of the total catch biomass. The niche breadth of major fish species ranged from 0. 07 to 1. 12, with no broad-niche species observed. Significant overlap was observed in 25. 72% of the 276 species pairs, and the degree of overlap was highest among Cyprinidae species within Cypriniformes. A total of 25 fish species were annotated using eDNA technology, belonging to 5 orders, 11 families, and 18 genera. The average relative abundances of Cyprinus carpio and Aristichthys nobilis reached 38. 53% and 21. 96%, respectively. The Chao1 index(41) and Shannon index(2. 236 4) at station S4 were the highest, while station S18 showed the lowest values(Shannon index 1. 399 4). 12. 8% of species were detected by both method, and comprehensive analysis indicated that approximately 40 fish species may be present in the reservoir. [Conclusion] Fish in Yuqiao Reservoir are dominated by Cypriniformes, and the community structure is significantly influenced by environmental heterogeneity. eDNA technology can effectively complement the limitations of morphological identification, and the combination of both method enables a more comprehensive assessment of fish diversity, providing a scientific basis for ecological protection in the reservoir area.

Keywords

environmental DNA / eDNA technology / Yuqiao Reservoir / fish diversity / niche breadth / niche overlap / morphological identification / influencing factors