Macroinvertebrates beta diversity and responses of functional traits to water environmental factors in the Qingyijiang River, China

Abstract

The diversity of functional traits of macroinvertebrates in freshwater ecosystems is one of the current research hotspots in the field of biodiversity. Understanding the functional trait composition of macroinvertebrates and their factors can make the study of watershed beta diversity and river ecological security patterns more effective. Based on two field surveys conducted in September 2020 and July 2021 in the Qingyijiang (QYJ) River, the longest tributary on the south bank of the lower Yangtze River in China, we explored the functional trait compositions of macroinvertebrates and relationships between functional traits and water environment factors using functional diversity indices, beta diversity decomposition, R‐mode linked to Q‐mode, and fourth‐corner analysis methods. Our results showed that water environmental factors affected the distribution of macroinvertebrates traits, and the degree of effect was reflected by the correlation between water environmental factors and the abundance of species traits. Physical factors like flow velocity and water depth were significantly correlated with biological traits of species such as body size and swimming ability. In counterparts, some nutrient indicators significantly affected species ecological traits, such as total phosphorus, ammonia nitrogen, and chemical oxygen demand, which affected species habits and functional feeding group traits. At the same time, we also found a high turnover rate between communities in the river, reflecting the strong dispersal ability of the species. This will be an important guide for the conservation of macroinvertebrates diversity in the river. Local governments can take measures such as conducting quarterly monitoring of macroinvertebrates species; restoring riparian vegetation; limiting hardening of riverbanks and dredging of rivers; controlling wastewater discharges from residential areas on both sides of the river; controlling the use of pesticides in agricultural lands, and so on. These will become the key directions for the conservation of macroinvertebrates diversity.