Interaction between the introduced eastern mosquitofish and two autochthonous Spanish toothcarps

Abstract

In aquaria, adults and young-of-the-year (YOY) of both Spanish toothcarp Aphanius iberus and Valencia toothcarp Valencia hispanica received more aggression in the presence of eastern mosquitofish Gambusia holbrooki. YOY of both species also showed decreased feeding rates, as did V. hispanica adults. Adult V. hispanica also were more aggressive themselves and had their reproductive behaviour disrupted. Cases of eastern mosquitofish predation on small A. iberus were also observed. The occurrence and intensity of these potentially harmful effects, however, seemed to be modulated by water temperature, reproductive condition, relative size of the interacting fishes and species-specific habitat preferences. Thus, aggression almost disappeared at low water temperatures. Valencia hispanica and eastern mosquitofish used similar vertical positions in the water column and this apparently increased the frequency of their interactions. In contrast, A. iberus preferred positions closer to the bottom than the other two species and this vertical segregation appeared to lead to less direct interaction with eastern mosquitofish. In an outdoor mesocosm experiment, under semi-natural conditions, the presence of eastern mosquitofish resulted in an almost 70% reduction in the number of offspring produced by A. iberus. The addition of extra, non-breeding males of A. iberus had no significant effect. YOY A. iberus from cages with eastern mosquitofish or extra males were significantly smaller (c. 1 mm, or 8% shorter) than those from cages without additional fish. Results for V. hispanica were not conclusive, as very few YOY were recovered. In contrast, eastern mosquitofish did not affect the survivorship of breeding adults of both native species.

Agonistic behavioral interactions between introduced western mosquitofish and native topminnows

“…For example, aggressive intraspecific interactions were positively correlated to fish density for age-0 Atlantic salmon Salmo salar and adult parrotfish Sparisoma viride (Mumby and Wabnitz 2002;Blanchet et al 2006). Further, Spanish toothcarp Aphanius iberus were chased and nipped more at higher eastern mosquitofish densities (Rinco et al 2002). Similar behaviors were observed among western mosquitofish conspecifics at higher fish densities in our study, where the greatest number of chases and nips occurred at the highest density of fish.…”

Temporal genetic dynamics among mosquitofish (Gambusia holbrooki) populations in invaded watersheds

“…A year later, a few hundred individuals from their offspring were transplanted to Italy (reviewed in NavarroGarcıa, 2013) and from there to every other European and Mediterranean country in the following years (Sholdt et al, 1972). Introduced mosquitofish are now playing a key role in Spanish Mediterranean freshwater ecosystems by competing and displacing endemic fish species such as the Spanish toothcarp, Aphanius iberus, and the Valencia toothcarp, Valencia hispanica (Rincon et al, 2002;Alcaraz et al, 2008;Carmona-Catot et al, 2013). The reduced genetic variation in mtDNA among European G. holbrooki populations supports the abovementioned historical records confirming a common source for the majority of these populations and indicates a notorious uniformity among Iberian populations (Vidal et al, 2010).…”

Application of the physical habitat simulation for fish species to assess environmental flows in an Atlantic Forest Stream in South-eastern Brazil

“…Moreover, fish size determines habitat selection (e.g. shallow or deep, slow or fast) as part of a strategy to avoid predation (Power, 1984) and/or facilitates obtaining food resources (Rincón et al, 2002). In this study we did not consider fish size classes because there is not literature available on the biological characteristics of these species, such as the size at the young of the year, juveniles or adults or size at first maturity.…”