Colorful invasion in permissive Neotropical ecosystems: establishment of ornamental non-native poeciliids of the genera Poecilia/Xiphophorus (Cyprinodontiformes: Poeciliidae) and management alternatives

Abstract

Headwater creeks are environments susceptible to invasion by non-native fishes. We evaluated the reproduction of 22 populations of the non-native livebearers guppy Poecilia reticulata, black molly Poecilia sphenops, Yucatan molly Poecilia velifera, green swordtail Xiphophorus hellerii, southern platyfish Xiphophorus maculatus, and variable platyfish Xiphophorus variatus during an annual cycle in five headwater creeks located in the largest South American ornamental aquaculture center, Paraíba do Sul River basin, southeastern Brazil. With few exceptions, females of most species were found reproducing (stages 2, 3, 4) all year round in the creeks and gravid females of all species showed small sizes indicating stunting. Juveniles were frequent in all sites. The fecundity of the six poeciliids was always low in all periods. The sex ratio was biased for females in most species, both bimonthly as for the whole period. Water temperature, water level and rainfall were not significantly correlated with reproduction in any species. Therefore, most populations appeared well established. The pertinence of different management actions, such as devices to prevent fish escape, eradication with rotenone and research about negative effects on native species, is discussed in the light of current aquaculture practices in the region.Keywords: Aquaculture, Invasive species, Livebearers, Reproduction, Stream.Riachos de cabeceira são ambientes susceptíveis à invasão por peixes não-nativos. Neste trabalho, avaliou-se a reprodução de 22 populações dos poecilídeos não-nativos guppy Poecilia reticulata, molinésia preta Poecilia sphenops, molinésia Poecilia velifera, espadinha Xiphophorus hellerii, plati Xiphophorus maculatus e plati variado Xiphophorus variatus durante diferentes anos em cinco riachos de cabeceira localizados no maior polo de piscicultura ornamental da América do Sul, bacia do rio Paraíba do Sul, sudeste do Brasil. Foram encontradas fêmeas da maioria das espécies em reprodução (estágios 2, 3, 4), durante todos os anos nos riachos e fêmeas grávidas de todas as espécies apresentaram pequeno tamanho indicando nanismo. Juvenis de todas as espécies foram frequentes em todos os locais. A fecundidade das seis espécies sempre foi baixa em todos os períodos. Para os períodos bimestrais e totais, encontrou-se mais fêmeas que machos na maioria das espécies. Temperatura e nível de água dos riachos, bem como precipitação pluviométrica não foram correlacionadas com a reprodução. Todas as populações estão estabelecidas nos locais e ações de gerenciamento como dispositivos para impedir a fuga de peixes, erradicação com rotenona e pesquisa científica sobre os efeitos negativos nas espécies nativas são discutidas em relação às práticas de piscicultura na região.

A network meta‐analysis of threats to South American fish biodiversity

“…Recent evaluations revealed that we should be concerned with the introduction of a “few widespread” species (Toussaint, Beauchard, et al., ), either unintentionally, because it culminates in biological invasions and biotic homogenization (Mazor et al., ; Pool & Olden, ; Toussaint, Charpin, et al., ). An outstanding example is the widespread occurrence of non‐native cichlid (Lima Junior et al., 2018) and cyprinid (Magalhães & Jacobi, ; Rodrigues‐Filho et al., ) fish in natural and artificial environments of South America and worldwide.…”

“…Aquarium trade, baiting, fish farming, sports fishing and stocking policies are the main activities resulting in the introduction of companion species, non‐native species that are introduced jointly with another non‐native species of economic relevance (Magalhães and Jacobi, ; Abilhoa, Bornatowski, & Vitule, ; Daga et al., ). Evolutionary novelties among newly introduced non‐natives, such as rapid growth and resistance to diseases, may confer advantages over the native biota (Padilla & Williams, ).…”

First record of the non‐nativeXiphophorus hellerii(Cyprinodontiformes: Poeciliidae), in the Iguazu River Basin, Paraná, Brazil

“…In this order, the family Poeciliidae comprises 42 genera with about 353 species (Nelson, Grande, & Wilson, ), which are small and laterally compressed fishes, with body form ranging from extremely elongated (e.g., Tomeurus ) to deep‐bodied (e.g., Phallichthys , Carlhubbsia ) (Lucinda, ). Some species have been introduced in many countries by ornamental aquarists (Magalhães & Jacobi, ), and as an alternative measure to biological control of mosquitoes (Azevedo‐Santos, Vitule, Pelicice, & García‐berthou, ). Seven species were already registered in Brazilian headwater streams (Magalhães & Jacobi, ).…”

Efectos de la especie invasora (Cyprinodontiformes: Poeciliidae) sobre Pseudopoecilia fria en ríos costeros de la región del Chocó, Ecuador

“…Revista de Biología Tropical,68(1),[122][123][124][125][126][127][128][129][130][131][132][133][134][135][136][137][138] caso de ciertas especies del género Poecilia, son la ovovivíparidad (Courtenay & Meffe, 1989), el cuidado parental (Magurran, Seghers, Carvalho, & Shaw, 1992) y la formación de cardúmenes (Camacho-Cervantes, García, Ojanguren, & Magurran, 2014a; Camacho-Cervantes, Ojanguren, Deacon, Ramnarine, & Magurran, 2014b); además, por ejemplo, las hembras de P. reticulata tiene la capacidad de almacenar esperma hasta por 10 meses (López-Sepulcre, Gordon, Paterson, Bentzen, & Reznick, 2013), lo que le permite a una hembra, por si misma, colonizar una nueva localidad, y fundar una población estable (Deacon, Ramnarine, & Magurran, 2011;Deacon & Magurran, 2016). Algunos autores (Meyer, Salzburger, & Schartl, 2006;Lampert & Schartl, 2008) reportan la hibridización entre especies emparentadas de Poecilia, lo que a su vez podría incrementar el riesgo de extinción para las especies locales (Magalhães & Jacobi, 2017). Se ha demostrado que los poeciliidos han sido la causa de la disminución en las poblaciones de algunos cyprínidos endémicos de Norteamérica (Magurran, 2009).…”