Impact of biological invasions on biodiversity

The overall aim of the INVABIOECOF (Biodiversity and ecosystem functioning: Individual-based modelling to understand and predict the consequences of biological invasions) project was to determine how non-random alterations of biodiversity caused by biological invasions may affect freshwater ecosystems.

An innovative approach was applied whereby stable isotope analyses were used to trace changes in the trophic structure of recipient communities. A functional trait approach was also used to investigate the roles of different species within the ecosystem. In addition, individual-based ecology was employed to determine how individuals interact with each other and their environment.

Investigations revealed that the introduction of non-native species modified the way in which organisms utilise food resources and therefore the transfer of energy within the ecosystem. Researchers also found that stable isotope analyses used to characterise food web structures were sensitive to environmental pressures associated to biological invasions. For instance, it was observed that the introduction of invasive fish increased the level of trophic similarity between communities.

The researchers also demonstrated the importance of human activities and fishery management practices in the structure of biological communities and especially the abundance of non-native species. One important invasive species, crayfish, when at high densities, was found to significantly modify ecosystem functioning by increasing the decomposition rate of leaf litter.

Differences in behaviour within invasive populations were shown to modify prey community and ecosystem functioning. This demonstrates the ecological importance of variability within a species when investigating the ecological impacts of biological invasions.

INVABIOECOF therefore increased our understanding of the ecological impacts of biological invasions by demonstrating the significance of intraspecific variability on trophic structure and ecosystem functioning. This new knowledge will help support decisions in freshwater management.