Multiple floods affect composition and community structure of the ground-dwelling arthropods in the riparian zone of the Three Gorges Reservoir

Abstract Operation of a large water reservoir would lead to profound impacts on the riparian ecosystem, especially on the local flora and fauna. As the greatest key water-control project in China, the Three Gorges Reservoir (TGR) attracted a lot of attention regarding its influences on the riparian ecosystem, but few studies looked at the ground-dwelling arthropods which play an important role as an ecological link between the aquatic and terrestrial ecosystems. In this study, we looked at the diversity, composition, and structure of ground-dwelling arthropod communities in the riparian zone near the estuary of Baijia Stream, a secondary tributary of the Three Gorges reservoir. Our results indicated that (i) the littoral zone provided important habitats for ground-dwelling arthropods, especially hygrophilous arthropods with good dispersal ability, including springtails, beetles, crickets, and wolf spiders; (ii) obviously temporal variations existed in the diversity, composition, and structure of arthropod communities, which is mainly affected by the migration ability of arthropods and the available habitat resources at a low water stage; (iii) due to the multiple floods, distinct spatial variations of arthropod communities were characterized by diverse indicator taxa zonal distributions of diversity values along the altitude gradient; (iv) the clustering distribution of dissimilarities varied between the sampling sites because of resources endowment. We concluded that there are abundant arthropod species in littoral zone of the TGR, and that they are characterized by spatial-temporal variations in their diversities and community structures, which is dominantly affected by the multiple water level fluctuations. Therefore, arthropods are important indicators for the littoral zone ecosystem health providing a great value for evaluating the TGR ecosystem evolution under artificial flow regulations.