Prey selectivity and ontogenetic diet shift of the globally invasive western mosquitofish (Gambusia affinis) in agriculturally impacted streams

Abstract

The dietary breadth of invaders can influence their success, and having a wide dietary niche can facilitate the spread and survival of invaders under a variety of resource scenarios. The western mosquitofish (Gambusia affinis) is a globally distributed freshwater invasive fish. The spread of G. affinis is associated with agricultural land use, although the trophic role it plays in degraded systems is not well understood. We analysed the invertebrate community in 11 stream reaches in the North Island of New Zealand, in catchments spanning a range (45%-90%) of agricultural land use to determine how prey availability changes with land use. We then analysed the gut contents of 400 G. affinis from the 11 sites to determine how diet varied with prey availability and ontogeny. Invertebrate communities varied along the agricultural land-use gradient, both in regard to taxonomic richness and community composition.G. affinis consumed a wide variety of food items with invertebrates being the most dominant, in particular Culicidae, Copepods and amphipods were the most commonly consumed invertebrates. There was also an ontogenetic diet shift from microinvertebrates (Cladocera, Copepods and diatoms) to larger invertebrates, including Culicidae, amphipods and terrestrial invertebrates. G. affinis are capable of consuming a wide variety of prey in agricultural streams; their preferred prey are generally pollution-tolerant taxa commonly found in degraded streams. Having a large level of dietary plasticity coupled with preferring prey that are often associated with degraded systems likely facilitates to the spread of one of the most widely distributed freshwater invasive fish. K E Y W O R D Sagriculture, diet plasticity, Gambusia affinis, invasive species | 823 LEE Et aL.

Urbanisation affects the diet and feeding selectivity of the invasive guppy Poecilia reticulata

“…The synergistic effects of synanthropic species seem to improve the population fitness of this guppy in urban streams, even though in other environments the availability of resources is greater (rural streams). This dietary flexibility probably offers competitive advantages when colonising and establishing in a new environment (Almeida, Almodóvar, Nicola, Elvira, & Grossman, 2012;Lee, Simon, & Perry, 2018), whatever the conservation status. This is shown by the results obtained for niche amplitude and prey selectivity, which provide insights into how the establishment processes and the potential impacts of this species on Neotropical streams.…”

Inter‐specific differences in invader and native fish functional responses illustrate neutral effects on prey but superior invader competitive ability

“…The impacts of mosquitofish were found to be more profound when differences in magnitudes of the FR between the two species are considered. The classic comparative approach therefore highlights that mosquitofish have the ability and feeding efficiency to cause greater field ecological damage, which further exacerbates its known global ecological impacts on native macroinvertebrate communities (Lee et al., ; Linden & Cech, ). However, growing literature on interactions between predators has shown that overall predation can result in positive MPE and negative MPE (Barrios‐O'Neill, Dick, Emmerson et al., ; Davenport & Chalcraft, ; Palacios, Malerba, & McCormick, ) and there are a number of ways in which MPE can be effectively determined (McCoy, Stier, & Osenberg, ; Sentis & Boukal, ; Sih, Englund, & Wooster, ; Wasserman, ).…”

“…The classic comparative approach therefore F I G U R E 1 Functional responses towards larval chironomid prey of: (a) invasive mosquitofish alone (Gambusia affinis) and native river goby alone (Glossogobius callidus); (b) mosquitofish alone and mosquitofish in the presence of river goby; and (c) river goby alone and river goby in the presence of mosquitofish. Shaded areas are bootstrapped 95% confidence intervals highlights that mosquitofish have the ability and feeding efficiency to cause greater field ecological damage, which further exacerbates its known global ecological impacts on native macroinvertebrate communities (Lee et al, 2018;Linden & Cech, 1990). However, growing literature on interactions between predators has shown that overall predation can result in positive MPE and negative MPE Davenport & Chalcraft, 2013;Palacios, Malerba, & McCormick, 2018) and there are a number of ways in which MPE can be effectively determined (McCoy, Stier, & Osenberg, 2012;Sentis & Boukal, 2018;Sih, Englund, & Wooster, 1998;Wasserman, 2016).…”

“…The mosquitofish has wide tolerance to environmental conditions and plasticity in life-history traits (Pyke, 2005). The broad dietary breadth of this species is one of the traits that makes it a successful invader (Lee, Simon, & Perry, 2018), yet its impact has not been assessed comparatively and there are few studies that quantitatively assess its impact (Billman, Wagner, & Arndt, 2007;Castleberry & Cech, 1990;Rehage, Barnett, & Sih, 2005). The river goby is naturally distributed along the eastern seaboard of the southern African coastline, between northern Mozambique and the Cape region of South Africa (Whitfield, 1998).…”

Phylogenetic analysis and ontogenetic changes in the cone opsins of the western mosquitofish (Gambusia affinis)

“…To date, research has only demonstrated that the western mosquitofish possesses all four phylogenetic classes of cone opsin genes, including two sws2 genes (sws2a and sws2b), but exactly how many cone opsins it has remains uncertain [32]. Moreover, previous studies indicate that the western mosquitofish may display ontogenetic changes in cone opsin expression profiles because it exhibits an ontogenetic dietary shift, colors are critical to it in the mating choice of both sexes, and sex steroid estrogen influences its cone opsin expression profiles [32][33][34][35][36].…”