Abstract
The establishment probability of introduced alien fish can be context dependent, varying according to factors including propagule pressure and biotic resistance. The influence of nutrient enrichment on establishment outcomes of alien fishes is uncertain, yet this is a common anthropogenic stressor of many freshwaters. Here, the small-bodied alien topmouth gudgeon Pseudorasbora parva was used in mesocosms to experimentally test how a gradient of nutrient enrichment affected their growth rates, recruitment and trophic ecology. A ‘Control’ represented ambient, mesotrophic conditions, while treatments covered three levels of nutrient enrichment: low (eutrophic), medium (hypertrophic) and high (very hypertrophic). Each mesocosm was seeded with 6 mature P. parva (equal sex ratio) at the start of their reproductive season. After 100 days, length increments of the adult fish were significantly elevated in the low treatment, and these fish had also produced significantly higher numbers of 0+ fish compared to all other treatments. The trophic niche width of the mature fish was substantially higher in the control than the treatments, but this did not appear to confer any advantages to them in somatic growth rate or reproductive output. These results suggest that the nutrient status of receiving waters can have substantial impacts on the outcomes of fish introductions, where eutrophic conditions can assist the rapid population establishment of some alien species.
Highlights
Biological invasions are a major threat to global biodiversity, with freshwater ecosystems and their native communities being sensitive to the impacts of invasive species (Gozlan et al 2010a; Dominguez Almela et al 2020)
The trophic niche width of the mature fish was substantially higher in the control than the treatments, but this did not appear to confer any advantages to them in somatic growth rate or reproductive output. These results suggest that the nutrient status of receiving waters can have substantial impacts on the outcomes of fish introductions, where eutrophic conditions can assist the rapid population establishment of some alien species
There were significant differences in adult P. parva growth rates (GLM: Wald v2 = 28.29, d.f. 3, P \ 0.01), with the length increments in the low treatment being significantly higher than the control and the other treatments (P \ 0.01) (Fig. 2a)
Summary
Biological invasions are a major threat to global biodiversity, with freshwater ecosystems and their native communities being sensitive to the impacts of invasive species (Gozlan et al 2010a; Dominguez Almela et al 2020). Human-induced environmental disturbances often favour the establishment and success of introduced species (Mack et al 2000; Leprieur et al 2008; Britton et al 2015), with the ‘Disturbance’ and ‘Increased resources availability’ hypotheses of invasion biology predicting that where environmental perturbations result in increased resource availability, there is an elevated likelihood of an introduced species establishing an invasive population (Catford et al 2009) These hypotheses are important in freshwaters as these ecosystems are often subject to anthropogenically driven nutrient enrichment, especially in developed countries (Harper 1991; Mason 1991). Their populations can exacerbate the issues associated with eutrophication through their predation on zooplankton reducing the grazing pressure on the phytoplankton communities, increasing the likelihood of substantial algal blooms (Olin et al 2006)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
