Functional dimension reveal impacts of non-native fishes on native fishes and ecosystem functionality

Anthropogenic-mediated invasions of non-native species are leading to
biodiversity loss in many trophic groups, with specific impacts on a wide
range of ecosystem functions and services. However, the impacts of
non-native species on native species and ecosystem multifunctionality are
not well understood, particularly due to the lack of long-term studies
that focus on the analysis of functional and phylogenetic diversities.
Using a comprehensive dataset spanning nearly 80 years from Lake Erhai,
China, we assessed the impact of non-native fishes on the multidimensional
diversity of native fishes, as well as the cascading effects on the
multifunctional components of the ecosystem, including productivity,
decomposition, and average multifunctionality. Over time, the
multidimensional diversity of non-native fishes steadily increased,
whereas that of native species declined markedly. Concurrently, both
ecosystem productivity and average multifunctionality exhibited
significant upward trends. Long‑term invasion by non‑native fishes was
significantly negatively correlated with the multidimensional diversity of
native fishes. A consistent convergence–divergence–convergence pattern was
observed in trait spaces and in functional and phylogenetic community
patterns of overall fish communities. Ecosystem multifunctionality
increased with non-native fish functional diversity, though this positive
relationship became negative at higher diversity levels. In contrast,
native fish functional diversity and environmental factors—including
average water level, Secchi depth, and annual precipitation—were
consistently negatively associated with multifunctionality. These findings
underscore the importance of integrating functional perspective in
biodiversity monitoring and management to enhance our understanding of,
and foster more effective strategies for addressing, the long-term impacts
of non-native species on native species and ecosystem multifunctionality.