<b>Diet of <i>Poecilia reticulata</i> Peters, 1959 in streams from Paraná River basin: influence of the urbanization

Abstract

ABSTRACT. This study aimed to assess the diet of Poecilia reticulata in rural (RS) and urban stream (US) and under seasonal influence. We hypothesized that rainfall have a strong negative impact on the diet of the species in the US, due to its abrupt effect on food resources; in RS this effect is less apparent. Both streams belong to Pirapó River sub-basin, Paraná River basin. Fishes were sampled bimonthly, between July 2007 and June 2008 in three sample sites along the longitudinal gradient of the streams, using electrofishing. According to the Feeding Index, in both streams the population consumed almost exclusively detritus associated with aquatic organisms (>95%), regardless of the hydrological period. The main taxa explored by fish were Simuliidae in RS and Chironomidae in US. The diet was significantly different between streams; however, the seasonal factor was not significant, showing that the results were partially consistent with the suggested proposal. In US stream the diet of the fish followed an ordinarily pattern found in urban environments. Thus, P. reticulata can be used as a tool to assess environmental conditions due to its ability to reach bioindicator organisms, such as Chironomidae species. Keywords: benthivorous fish, feeding, macroinvertebrates, anthropic impact, Paraná River basin.Dieta de Poecilia reticulata Peters, 1959 em riachos da bacia do rio Paraná: influência da urbanização RESUMO. Este estudo objetivou investigar a dieta de Poecilia reticulata, em riacho rural (RR) e urbano (RU), sob influência sazonal. Foi hipotetizado que a chuva tem forte impacto negativo na dieta da espécie no RU, devido ao efeito abrupto sobre os recursos alimentares disponíveis, sendo este menos aparente em RR. Os riachos pertencem à sub-bacia hidrográfica do rio Pirapó, bacia do rio Paraná. Os peixes foram amostrados bimestralmente entre julho de 2007 e junho de 2008 em três pontos ao longo do gradiente longitudinal dos riachos, usando pesca elétrica. De acordo com o Índice alimentar, em ambos os riachos as populações consumiram quase que exclusivamente detrito associado com organismos aquáticos (>95%) independente do período hidrológico, sendo os principais: Simuliidae no RR e Chironomidae no RU. Houve diferença significativa na dieta entre os dois riachos, porém o fator sazonal não foi significativo, mostrando que os resultados foram parcialmente consistentes com a proposta sugerida. No RU a dieta mostrou um padrão comumente encontrado em ambientes urbanos. Dessa forma, P. reticulata pode ser usada como ferramenta para avaliar condições ambientais devido à sua habilidade em consumir organismos bioindicadores, tais como espécies de Chironomidae.Palavras-chave: peixe bentívoro, alimentação, impacto antrópico, bacia do rio Paraná. IntroductionThe fast radial expansion of urban centers has had as consequence the habitat degradation, and it reflects upon natural resources and aquatic ecosystems (Lee, 2000;Fogaça, Gomes, & Higuti, 2013). Regarding streams in urban areas, the status of degradation is more accele...

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

“…On the other hand, although individuals from the HPU streams presented lower variability of items, they presented a larger quantity of the same item, which was predominantly composed of Chironomidae larvae. These results also verified by Alves et al () reflect the influence of urban disturbances on aquatic macroinvertebrates, since the greater the impacts of urbanisation, the greater the dominance of tolerant taxa (e.g. Chironomidae; Ramírez, De Jesús‐Crespo, Martinó‐Cardona, Martínez‐Rivera, & Burgos‐Caraballo, ), thereby increasing their availability to their predators.…”

“…Its introduction in nonnative environments is mainly related to mosquito control, and often, its population exhibits explosive growth (El-Sabaawi et al, 2016). This species is opportunistic, omnivorous and bottom-dwelling (Lawal, Edokpayi, & Osibona, 2012), feeding on algae, invertebrates and detritus (Alves, Tófoli, Ganassin, & Hahn, 2016;Dussalt & Kramer, 1981). In its natural environment, the food selectivity of P. reticulata depends on biotic factors, especially predation.…”

“…Invasive guppies are characterised by extremely high abundances, biotic and abiotic resistance and dependence on benthic food resources are important features of these species (Alves et al, 2016). Therefore, identifying feeding adaptations of P. reticulata in alternative environmental conditions is fundamental for environmental assessment of streams, and this may provide insights on the establishment process of the species.…”

“…Therefore, identifying feeding adaptations of P. reticulata in alternative environmental conditions is fundamental for environmental assessment of streams, and this may provide insights on the establishment process of the species. In addition, the relevance of identifying species links in local food webs (Alves et al, 2016;Mise, Souza, Pagotto, & Goulart, 2015), allows a better understanding of the success of synanthropic species in urban environment (El-Sabaawi, 2018).…”

“…The diet of this species was evaluated for two streams (one rural and one urban) in the same region (Alves et al, 2016). However, the present study comes to complement the first, in order to make the results more general, increasing the number of sampling sites and testing more specific questions on dietary specialisation of these poeciliids (prey selectivity).…”