Behavioural interactions between the introduced plague minnow Gambusia holbrooki and the vulnerable native Australian ornate rainbowfish Rhadinocentrus ornatus, under experimental conditions

Abstract

The impact of the plague minnow Gambusia holbrooki on the ornate rainbowfish Rhadinocentrus ornatus was investigated by comparing the behavioural response and microhabitat preferences of populations of R. ornatus collected from locations that are sympatric and allopatric with G. holbrooki. Rhadinocentrus ornatus populations from sympatric areas exhibited a significantly higher frequency of intraspecific chases, spent significantly more time at an intermediate depth and were nipped significantly less often by G. holbrooki compared to the allopatric R. ornatus populations. The frequency of intraspecific chases by all R. ornatus populations were greatest immediately following G. holbrooki exposure and increased further with repeated exposure. Activity levels were also significantly higher in the presence of G. holbrooki. Gambusia holbrooki and the allopatric R. ornatus populations showed very similar microhabitat preferences, whereas the preferences for the sympatric R. ornatus populations have shifted to facilitate cohabitation with G. holbrooki. The results suggest that sympatric populations of R. ornatus have evolved or developed behavioural responses to G. holbrooki through niche and character shifts. The implications are discussed in relation to the conservation management of R. ornatus and other threatened species.

Predator recognition and responses in the endangered Macquarie perch (Macquaria australasica)

“…Similarly, ornate rainbowfish, Rhadinocentrus ornatus, has showed higher levels of aggression and activity in the presence of gambusia. Moreover, populations that have lived in sympatry with gambusia for multiple generations have showed evidence of niche and character shifts that seem to enhance their ability to live along-side this aggressive invasive species (Keller and Brown 2008). Such repeated negative interactions with invasive species have resulted in reduced feeding, growth and reproduction in native fish (Howe et al 1997).…”

“…Some of the more direct impacts include predation, competition and the introduction and transport of diseases. For example, Gambusia holbrooki, is well known for its aggressive nature and it not only attacks native fish and crustaceans causing death or displacement, but it also competes for food (Keller and Brown 2008;Bool et al 2011). The Murray-Darling Basin is a particularly good example of how prevalent invasive fish are in Australia; ,43% of the individuals present are non-native, equating to 68% of the total biomass (Davies et al 2010).…”

Prey utilisation and trophic overlap between the non native mosquitofish and a native fish in two Mediterranean rivers

“…This difference in terrestrial prey consumption cannot be attributed to differences in their morphology, since both species have a flattened head and a terminal, upward mouth that would in both cases enhance surface feeding (Barbieri et al, 2000;Pyke, 2005). It could, however, indicate a displacement of V. letourneuxi from the surface in the habitats where the two species co-occur, as a form of competition induced niche shift, similar to that induced to the Andalusian toothcarp Aphanius baeticus Doadrio, Carmona & Fernández Delgado, 2002 by its co-occurring species, and to other native fishes by the mosquitofish (Clavero et al, 2007;Arthington, 1991;Keller & Brown, 2008). Indeed, preliminary data comparing the diet of a sympatric versus an allopatric V. letourneuxi population in two similar freshwater habitats seem to corroborate the above assumption (Kalogianni et al, unpublished data).…”

Trophic plasticity of invasive juvenile largemouth bass Micropterus salmoides in Iberian streams

“…Not surprisingly, fishes are the most common invasive species in inland waters (Cowx, 1998;Ribeiro et al, 2008;Welcomme, 1998). Invasive fishes have a variety of adverse impacts on native species and habitats, such as hybridization (Madeira et al, 2005;Sanz et al, 2006), as a vector of diseases (Gozlan et al, 2005), food web alteration (Almeida et al, 2009;Blanco-Garrido et al, 2008), habitat degradation (García-Berthou, 2001), interspecific competition (Hazelton and Grossman, 2009a,b;Keller and Brown, 2008) and predation (Pearson and Goater, 2009;Schilling et al, 2009). Of these effects, predation is particularly important in the Iberian Peninsula (Carol et al, 2009;García-Berthou, 2002;.…”