Biotic resistance to fish invasions in southern China: Evidence from biomass, habitat, and fertility limitation

Abstract

Understanding the mechanisms underlying the invasion success or failure of alien species can help to predict future invasions and cope with the invaders. The biotic resistance hypothesis posits that diverse communities are more resistant to invasion. While many studies have examined this hypothesis, the majority of them have focused on the relationship between alien and native species richness in plant communities, and results have often been inconsistent. In southern China, many rivers have been invaded by alien fish species, providing an opportunity to test the resistance of native fish communities to alien fish invasions. Using survey data for 60,155 freshwater fish collected from five main rivers of southern China for 3 years, we assessed the relationships between native fish richness and the richness and biomass of alien fishes at river and reach spatial scales, respectively. Based on two manipulative experiments, we further examined the impact of native fish richness on habitat selection and the reproductive ability of an exotic model species Coptodon zillii. We found no apparent relationship between alien and native fish richness, whereas the biomass of alien fish significantly decreased with increasing native fish richness. In experiments, C. zillii preferred to invade those habitats that had low native fish richness, given evenly distributed food resources; reproduction of C. zillii was strongly depressed by a native carnivorous fish Channa maculata. Together, our results indicate that native fish diversity can continue to provide biotic resistance to alien fish species in terms of limiting their growth, habitat selection, and reproduction when these aliens have successfully invaded southern China. We thus advocate for fish biodiversity conservation, especially for key species, to mitigate against the population development and ecological impact of alien fish species.

Cannibalism facilitates and sustains the invasion of top‐predator fish (Cichlidae: Cichla) in human‐modified ecosystems

“…Cannibalism may be associated with the additive and synergistic impacts of habitat degradation and biological invasions for various reasons. Firstly, because natural and diversified ecosystems tend to sustain more complex trophic interactions and greater resistance to invasions (i.e., Biotic Resistance Theory; Elton, 1958; Gu et al., 2023). This can translate into greater availability of native prey (lower cannibalistic propension) in the diet and a lower abundance of predators.…”

Perspectives of invasive alien species management in China

“…Understanding why some communities are more readily invaded than others is a primary goal of invasion ecology and conservation biology. The study by Gu et al (2023) supported the biotic resistance hypothesis in freshwater ecosystems and suggested that protecting freshwater fish diversity is an important and effective pathway to mitigate the impacts of alien fishes.…”