Distribution of guppies Poecilia reticulata (Peters, 1860) and Phalloceros caudimaculatus (Hensel, 1868) along a polluted stretch of the Paraíba do Sul River, Brazil

Abstract

Cyprinodontiformes fishes (guppies) are widely distributed in Neotropical regions and use deteriorated microhabitats in rivers where few species can occur. This study was carried out in a stretch of the Paraíba do Sul River in bracketing a large urban-industrial complex. The aim was to assess eventual effects that the industrial complex could have on distribution of two closely related fish species of guppies, Phalloceros caudimaculatus and Poecilia reticulata. The area was divided into three zones: Z1, 40 km upriver of the major urban-industrial complex of Volta Redonda; Z2, just down river of the complex; and Z3, 30 km down river of the complex. Six sites (two in each zone) were sampled monthly between November 1998 and October 1999, using a standardized fishing effort with cast net throws, trays lifts and seine hauls, covering different microhabitats, that is, riffles, pools and the proximity of the river's margins. Poecilia reticulata was widely distributed, peaking at Z2, the most polluted area, while P. caudimaculatus showed the highest abundance at Z3, being almost absent in Z1. Both species occurred in high numbers throughout the year but they were scarce between April and June. Females outnumbered males for both species in most size classes and at all sites. Juveniles were more abundant than adults, with non-pregnant females outnumbering pregnant ones. Condition factor was always higher in males than females but only males P. reticulata showed significant difference among the three zones, with the highest values at Z2. The higher number of females confirms the expectation that these species can use very polluted areas and that availability of food provided by organic loads allowed their distribution all over the area. Although these two species have shown indication of spatial separation in the study area, their similar seasonal patterns of occurrence suggest that they respond in a similar way to changes in environmental conditions. Keywords: pollution, distribution, Cyprinodontiformes, population structure, Paraíba do Sul River. Redonda; Z2, imediatamente abaixo do complexo industrial; e Z3, 30 km abaixo do complexo. Seis locais (dois em cada zona) foram amostrados mensalmente entre novembro de 1998 e outubro de 1999, usando um esforço de pesca estandardizado com tarrafas, peneiras e arrastos, cobrindo diferentes microhábitats, isto é, corredeiras, remansos e a proximidade da margem dos rios. Poecilia reticulata foi largamente distribuído, apresentando pico na Z2, área mais poluída, enquanto P. caudimaculatus apresentou a maior abundância na Z3, sendo quase ausente na Z1. Ambas as espécies ocorreram em elevados números ao longo do ano, mas foram escassas entre abril e junho. Fêmeas foram mais numerosas do que machos para ambas as espécies na maioria das classes de tamanho e em todos os locais. Jovens foram mais abundantes que adultos, com fêmeas não grávidas predominando sobre fêmeas grávidas. Fator de condição foi sempre maior nos machos do que nas fêmeas, mas somente machos de P. reticulata a...

Influence of environmental quality of the tributaries of the Monjolinho River on the relative condition factor (Kn) of the local ichthyofauna

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Ichthyofauna from the Parque Nacional da Serra dos Órgãos and its surrounding areas, Rio de Janeiro state, Brazil

“…Characins inhabit several aquatic habitats such as streams, rivers, lagoons and reservoirs in different levels of environmental quality, whereas the poecilids are known for their capacity to colonize a wide range of degraded habitats tolerating low water quality where other species cannot tolerate (Araújo et al 2009;Teixeira et al 2005).…”

E-commerce of freshwater aquarium fishes: potential disseminator of exotic species in Brazil

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“…Many aquarium species, such as fishes, are highly invasive and the ecological impacts associated with these introductions are well documented (CONTRERAS-MACBEATH et al, 1998;DUGGAN et al, 2006;LIANG et al, 2006;RIXON et al, 2005). Because their invasive reputation is largely unknown to the layperson, these species are still extremely popular among professional aquarists and home hobbyists because they are attractive, relatively cheap, and easy to maintain and breed (LIANG et al, 2006).…”