Abstract
Invasive non-native species have pervasive impacts on native biodiversity, including population extirpations and species extinctions. Identifying reasons why a population of a native species is extirpated following an invasion often relies on literature-based results of anecdotal observations. The well-established schemes of existing risk assessments for invasive species assume that a species’ information (e.g. impacts or behavioural and biological traits) can be projected from one area to another to estimate the potential impact of a species in another environment. We used stable isotope data (δ13C, δ15N) from both invaded and uninvaded communities to predict such invasion impacts by reconstructing trophic relationships. This approach was tested on a community within a protected lake in Northern Spain where, following the introductions of non-native species, the last resident native species (the common tench Tinca tinca, the European eel Anguilla anguilla, and the whirligig beetle Gyrinus sp.) had been extirpated. Through the application of this novel approach, we found evidence that native species’ declines were related to direct predation by and resource overlap with non-native species, which occurred in conjunction with habitat modification. Using this approach, we outlined the mechanisms involved in the extirpation of native species in the post-invasion period. To compensate for losses of native species induced by invasions of non-native species, native species reintroductions might be an appropriate tool. For this, we further suggested and discussed a novel approach that predicts the outcome of arising interactions by superimposing stable isotope data from alternative sources to better estimate the success of native species´ reintroductions.
Highlights
Invasive non-native species have pervasive impacts on native biodiversity, including population extirpations and species extinctions
The extent to which these approaches can scale up to predict impacts in more complex systems can have high context dependency[24,25]. More recent methods, such as stable isotope analysis ( SIA26), provide new possibilities to investigate aquatic invasion risks and their associated impacts. This is especially pertinent in invaded communities where there is a high level of complexity in species interactions, which in turn could potentially lead to novel, but often less conspicuous impacts on native species and aspects of their habitats[27,28]
Using our proposed approach from scenario (b), we argue that in the case of Gyrinus sp., this would mean a decrease in the abundance of the invasive species P. clarkii and L. gibbosus, and a recovery of natural vegetation and terrestrial insects in the proximity of Arreo Lake that could be predated by Gyrinus sp
Summary
Invasive non-native species have pervasive impacts on native biodiversity, including population extirpations and species extinctions. We used stable isotope data (δ13C, δ15N) from both invaded and uninvaded communities to predict such invasion impacts by reconstructing trophic relationships This approach was tested on a community within a protected lake in Northern Spain where, following the introductions of non-native species, the last resident native species (the common tench Tinca tinca, the European eel Anguilla anguilla, and the whirligig beetle Gyrinus sp.) had been extirpated. More recent methods, such as stable isotope analysis ( SIA26), provide new possibilities to investigate aquatic invasion risks and their associated impacts This is especially pertinent in invaded communities where there is a high level of complexity in species interactions, which in turn could potentially lead to novel, but often less conspicuous impacts on native species and aspects of their habitats[27,28]. The presence of the crayfish Procambarus clarkii has led to disruptions of the habitat and the native flora, leading to the dominance of Phragmites australis and Cladium mariscus; both non-native plants[5]
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