6/1/2023 0 Comments Non aggressive freshwater fishWestern mosquitofish Gambusia affinis (Baird & Girard, 1853) is listed as one of the 100 worst invasive species by the International Union for Conservation of Nature and has been implicated in the decline of freshwater fish, amphibians, and invertebrates. Mechanisms of displacement may include agonistic interactions, where aggressive behaviors by nonnative species push native species out of their preferred habitat, including their thermal optima. Nonnative fish are implicated in the demise of native fish globally, but a mechanistic understanding of how displacements take place is often lacking. Future research should examine other life history traits that may be conveying the competitive advantage to G. ![]() This study provided the novel approach using of a thermally heterogeneous thermal chamber to examine thermal preferences and aggressive interactions between a native and an invasive species. Biological invasions are a global issue and altered thermal regimes are expected to continue. affinis toward native fish species may be species- and condition-specific, and may not always be the primary mechanism of native species’ displacement. These results indicate that agonistic behavior of G. Contrary to our prediction, more agonistic interactions were observed in C. eos increased by 1.7 ☌ and the movement, given by distance (cm) travelled, increased by 21%. ![]() affinis’ introduction, the thermal preference of C. eos selected an average of 24.3 ☌ as its thermal preference. ![]() Given the temperature range of the experimental chamber, i.e., 20–30 ☌, C. affinis is widely recognized as an aggressive invader. affinis would express agonistic behavior toward C. To examine these interactions, we built an experimental thermal preference chamber to evaluate: (1) the thermal preference of native, glacial relict northern redbelly dace Chrosomus eos (2) if the thermal preference and movement changed in the presence of the invasive western mosquitofish Gambusia affinis and (3) the direction of agonistic interactions. Mechanisms of the displacement of native fish by nonnative fish can include agonistic behaviors that push native fish species out of their preferred habitat, including their thermal optima.
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