Abstract
Measuring ecological and economic impacts of invasive species is necessary for managing invaded food webs. Based on abundance, biomass and diet data of autochthonous and allochthonous fish species, we proposed a novel approach to quantifying trophic interaction strengths in terms of number of individuals and biomass that each species subtract to the others in the food web. This allowed to estimate the economic loss associated to the impact of an invasive species on commercial fish stocks, as well as the resilience of invaded food webs to further perturbations. As case study, we measured the impact of the invasive bass Micropterus salmoides in two lake communities differing in food web complexity and species richness, as well as the biotic resistance of autochthonous and allochthonous fish species against the invader. Resistance to the invader was higher, while its ecological and economic impact was lower, in the more complex and species-rich food web. The percid Perca fluviatilis and the whitefish Coregonus lavaretus were the two species that most limited the invader, representing meaningful targets for conservation biological control strategies. In both food webs, the limiting effect of allochthonous species against M. salmoides was higher than the effect of autochthonous ones. Simulations predicted that the eradication of the invader would increase food web resilience, while that an increase in fish diversity would preserve resilience also at high abundances of M. salmoides. Our results support the conservation of biodiverse food webs as a way to mitigate the impact of bass invasion in lake ecosystems. Notably, the proposed approach could be applied to any habitat and animal species whenever biomass and diet data can be obtained.
Highlights
Invasive species are among the main causes of biodiversity loss and changes in ecosystems (Gozlan et al 2010; Gallardo et al 2016), and their impact is expected to increase worldwide due to climate warming and human action (McClelland et al 2018; Ricciardi et al 2017)
Excluding M. salmoides, 3 autochthonous and 3 allochthonous fish species were found in North, while 7 autochthonous and 6 allochthonous species were found in South
Biomass and diet data of species, we proposed a method for quantifying trophic interaction strengths in terms of number of individuals and biomass that each species subtracts to the others through competition and/or predation in invaded food webs
Summary
Invasive species are among the main causes of biodiversity loss and changes in ecosystems (Gozlan et al 2010; Gallardo et al 2016), and their impact is expected to increase worldwide due to climate warming and human action (McClelland et al 2018; Ricciardi et al 2017). While research in the field has increased during recent years (Dick et al 2017b; Laverty et al 2017; Corrales et al 2019), our ability to measure the ecological and economic impact of invaders in natural communities is still limited (Kulhanek et al 2011; Crystal-Ornelas and Lockwood 2020) In this context, the quantification of the impact of biological invasions on complex food webs and key ecosystem services (including the productivity of commercially exploited species) is necessary to formulate effective management strategies (Gozlan et al 2010; Davies and Britton 2015; Latombe et al 2017). This hinders an effective conservation and management of invaded communities, which may be exposed to other environmental stressors (e.g. habitat degradation) that interact with invasion, impairing the persistence of food webs (Didham et al 2007; Prior et al 2017; Norbury and van Overmeire 2019)
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