How fish traits and functional diversity respond to environmental changes and species invasion in the largest river in Southeastern China

Abstract

Background Freshwater fish populations are facing multiple stressors, including climate change, species invasion, and anthropogenic interference. Temporal studies of fish functional diversity and community assembly rules based on trait-environment relationships provide insights into fish community structure in riverine ecosystems. Methods Fish samples were collected in 2015 in the Min River, the largest freshwater riverine system in Southeastern China. Fish functional diversity was compared with the background investigation in 1979. Changes in functional richness, functional evenness, functional divergence, and functional beta diversity were analyzed. Relationships between functional diversity and environmental factors were modeled by random forest regression. Correlations between fish functional traits and environmental factors were detected by fourth-corner combined with RLQ analysis. Results Functional richness was significantly reduced in 2015 compared with 1979. Functional beta diversity in 2015 was significantly higher than that in 1979, with functional nestedness being the driving component. Reduction of functional richness and domination of functional nestedness is associated with species loss. Trait convergence was the dominant mechanism driving the temporal changes of functional diversity. Precipitation, temperature, species invasion, and human population were the most significant factors driving fish functional diversity. Higher precipitation, higher temperature, and presence of invasive species were significantly associated with higher swimming factor and higher relative eye diameter, while the opposite environmental conditions were significantly associated with higher pectoral fin length and eurytopic water flow preference. Conclusions Environmental filtering is the dominant temporal assembly mechanism shaping fish community structure. This work contributes to the understanding of temporal freshwater fish community assembly and the associations between fish functional structure and local environmental conditions, which will be informative for future freshwater fish conservation.

Patterns of functional diversity of native and non‐native fish species in a neotropical floodplain

“…Another study by Lin et al. (2021) also found a significant reduction in the functional richness of fish species from the Min River (China) after 36 years of environmental changes and species invasion. Conversely, a study by Pereira et al.…”

“…A functional approach provides more information about community responses to disturbances (Mouillot et al., 2013; Suding et al., 2005), such damming of rivers (Lin et al., 2021; Oliveira et al., 2018; Pereira et al., 2021; Zhang et al., 2020), and invasion by non‐native species (Shuai et al., 2018). For example, Oliveira et al.…”

“…A functional approach provides more information about community responses to disturbances (Mouillot et al, 2013;Suding et al, 2005), such damming of rivers (Lin et al, 2021;Oliveira et al, 2018;Pereira et al, 2021;Zhang et al, 2020), and invasion by non-native species (Shuai et al, 2018). For example, Oliveira 2021) also found a significant reduction in the functional richness of fish species from the Min River (China) after 36 years of environmental changes and species invasion.…”

Introduction of non‐native fish for aquaculture in China: A systematic review

“…244,245 Native species migrating into different areas within a basin may play an even greater role in driving fauna homogenization, 246 and sharply reducing the beta diversity between different regions. 247 Almost all provinces in China have a history of domestic translocation (introducing fish non-native to a region but native to the country) for aquaculture. 248 Unfortunately, the ecological impact of the migration of native species into water bodies where it would not occur naturally (migration between different watersheds and between different areas of the same watersheds) has been completely overlooked in China.…”

“…258 In Minjiang River in Fujian Province, L. cyanellus even became the dominant species. 247 The appearances of sunfish in in multiple locations not only pose a threat to the respectively native species, but also reduce faunal heterogeneity to a large extent. Introduced catfish are also popular farmed objects and have contributed to fauna homogenization of these areas, for example, North African catfish Clarias gariepinus and channel catfish successfully established and expanded populations in nearly all the rivers in south China.…”