Global impacts of Aquatic Invaders

The introduction of invasive species, which often differ functionally from the native community, generates ecological impacts that propagate along the food web. This review aims to determine how consistent the impacts of aquatic invasions are across taxa and habitats. We undertook an ambitious review and meta-analysis of over 700 cases of aquatic invasions, covering a wide range of invaders (primary producers, filter collectors, omnivores and predators), resident aquatic communities (from algae to fish) and habitats (rivers, lakes and estuaries) (Gallardo et al. 2015a). Our synthesis confirmed and quantified the strong negative influence of invasive species on the abundance of aquatic communities (Fig 1).

Trophic model summarizing links confirmed by Gallardo et al. (2015a). Arrows reflect the negative (red) or positive (blue) impacts of invasive species on the abundance of five different functional components of the aquatic food web. The thickness of arrows is proportional to the mean effect sizes calculated through a meta-analysis.

EU workshops directed to support the implementation of the EU Regulation 1143/2015 on Invasive species (Roy et al. 2014, Roy et al. 2015) and the COST Action Alien Challenge. My participation in those international panels of experts has led to collaborative publications developing a framework of minimum standars for the risk assessment of invasive species (Roy et al. 2018c), a prioritized list of invasive species in Europe (Carboneras et al. 2017, Roy et al. 2018b) and a comprehensive evalutation of pathways of biological invasions (Essl et al. 2015). In addition, I have supervised two undergraduate projects (TFG), further evaluating the potential distribution and impacts of aquatic invasive species in Europe.

Corbicula fluminea in the Ebro River. Photo: Joaquín Guerrero

Gallardo, B., Clavero, M., Sanchez, M.I. and Vilà, M. (2015a) Global ecological impacts of invasive species in aquatic ecosystems. Global Change Biology 22(1), 151-163.