Intraguild predation may facilitate coexistence of native and non‐native fish

Abstract

Summary1. Although largely ignored, coexistence of native species with non-native species is the rule rather than the exception in the contemporary world. Therefore, understanding the mechanisms that facilitate coexistence of native species with non-native invasive species is critical in implementing effective management strategies to conserve native biodiversity. 2. We conducted field mesocosm experiments to study reciprocal predation between an invasive fish species (Western mosquitofish Gambusia affinis) and an endangered fish species (Mohave tui chub Siphateles bicolor mohavensis). Additional predation vulnerability modelling was conducted to assess the vulnerability of a given prey population to predation by a gapesize limited predator population. 3. Adult mosquitofish reduced Mohave tui chub recruitment through predation on tui chub larvae. Reciprocally, adult tui chubs limited the population growth of mosquitofish through predation on adult mosquitofish, providing evidence for intraguild predation (IGP). Mohave tui chub predation on adult mosquitofish was apparently gape-size limited and larger female mosquitofish avoided tui chub predation. 4. Vulnerability modelling provided additional information on gape-size limited reciprocal predation between these two fish species and insights on the effects of such IGP on persistence of Mohave tui chub in the presence of invasive mosquitofish. 5. Synthesis and applications. Our results collectively show size-structured intraguild predation (IGP) between a native endangered fish and an invasive fish species, which may facilitate coexistence of these species. Invasive species often prey on native species, thus IGP may be a common but neglected phenomenon for invaded systems. Therefore, understanding the complex interactions among native and non-native species in the whole-ecosystem context may help conservation practitioners identify novel management strategies. This may be especially necessary when natural, uninvaded habitats for native species become increasingly scarce due to alterations resulting from multiple forms of human impact.

Responses of a wetland ecosystem to the controlled introduction of invasive fish

“…Webb & Joss, 1997;Zeiber, Sutton & Fisher, 2008;Shulse, Semlitsch & Trauth, 2013) and fishes (e.g. Mills, Rader & Belk, 2004;Henkanaththegedara & Stockwell, 2014). Most native amphibian species from the western United States are susceptible to mosquitofish predation (Gamradt & Kats, 1996;Goodsell & Kats, 1999;Preston, Henderson & Johnson, 2012), although at least one wetland experiment (Lawler et al, 1999) and our own observations in northern California suggest that mosquitofish coexist with native amphibians in some settings.…”

Field data and worldwide literature review reveal that alien crayfish mitigate the predation impact of the American bullfrog on native amphibians

“…The identification and quantification of interactions among invaders, and between invaders and native species, is therefore an issue urgently requiring further long‐term observational and manipulative studies (Simberloff & Von Holle, ). The identification of mechanisms facilitating the coexistence of native species with invaders, in particular, can offer important management options (Henkanaththegedara & Stockwell, ). As confirmed by the present study, alien species management may have both positive and negative consequences for native species; in light of such conflicting consequences it is difficult to know a priori which management option would make matters better or worse (Rinella, Maxwell, Fay, Weaver, & Sheley, ).…”

“…To do so: (i) introduced populations of American bullfrogs were investigated at two sites in central Italy (Rome, Latium), selected based on the presence or absence of the alien red swamp crayfish Procambarus clarkii ; (ii) the pattern emerging from the fieldwork was supplemented and verified by a worldwide literature review on the trophic niche of the American bullfrog. Understanding the complex interactions among native and alien species in the context of the whole ecosystem may help conservation practitioners to identify novel management options (Henkanaththegedara & Stockwell, ).…”

The Impacts of Recently Established Fish Populations on Zooplankton Communities in a Desert Spring, and Potential Conflicts in Setting Conservation Goals

“…These fish densities were chosen to reflect relative densities and sex ratios in Lake Tuendae [34]. The final fish population size upon completion of this experiment was reported elsewhere [35]. We did not include Saratoga Springs pupfish, because this species was at very low density when our experiments were conducted.…”