Interacting effects of habitat degradation and biological invasion: fish stocks and food web stability in aquatic ecosystems, a novel approach based on quantitative food web description
Biological invasions and habitat degradation represent the two major threats to biodiversity. However, due to the frequent co-occurrence of these factors, the ultimate mechanism driving biodiversity loss is often unclear. Effective conservation actions depend on accurate identification of the relative roles of biological invasion and habitat degradation to biodiversity loss, including their interacting effects on the structure and functioning of food webs. Indeed, biotic interactions can modify stressor effects, and key ecological properties including energy flux, vulnerability of communities to biodiversity loss and resilience to perturbations are related to the architecture of food webs.
Thanks to the stable isotope-based description of food web structures, this project will provide robust information on the effect of habitat degradation, species invasion and their interaction on biodiversity and on the architecture of invaded food webs. The project will focus on aquatic Mediterranean habitats, and specifically on fish communities including species of high conservational and commercial value. The quantification of trophic interactions will allow to measure the impact of invaders on native species, as well as the limiting effect of natives against invaders. A network analysis will provide unprecedented insights on the effect of invasive species on the vulnerability to biodiversity loss and resilience to additional stressors of invaded food webs under varying habitat conditions.
Results and procedures arising from this study will represent a step toward building a better quantitative understanding of how interactions between habitat degradation and biological invasions drive their net effect on the structure and functioning of biotic communities, providing clear advices supporting conservation management. Although our case studies rely on aquatic ecosystems, the approach we present is founded on ecological theory and is thus transferable to most other ecosystems.