Influência da urbanização sobre as assembléias de peixes em três córregos de Maringá, Paraná

Abstract

O objetivo do presente estudo foi avaliar padrões espaciais na composição, estrutura e distribuição das assembléias de peixes e suas relações com características abióticas em três córregos urbanos da cidade de Maringá, Paraná, Brasil. Peixes foram coletados ao longo de um gradiente longitudinal utilizando pesca elétrica nos meses de maio e novembro de 2004. Temperatura, nitrogênio, pH, oxigênio e fósforo foram as variáveis que mais influenciaram a análise de componentes principais (CPA). Riqueza, eqüitabilidade, índice de diversidade de Shannon-Wiener e o primeiro eixo da análise de correspondência com remoção do efeito do arco (DCA) foram diretamente correlacionados com características ligadas ao impacto químico urbano. Adição de espécies prevaleceu nas estações de amostragem do córrego Miosótis e entre a cabeceira e porção intermediária nos córregos Nazaré e Mandacaru. Substituição ocorreu entre as porções intermediárias e foz desses córregos. A dominância da espécie tolerante Poecilia reticulata Peters, 1859 indicou a influência do impacto do meio urbano sobre as assembléias de peixes.

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

“…This has already been observed for this species by Lemes & Garutti (2002), Dyer (2003) and Cunico et al (2006) who reported a high density of this species in impacted streams. According to Oliveira & Bennemann (2005), Poecilia reticulata is an exotic species that shows resilience in environments disturbed by human activity, owing to its opportunistic habits and diversified diets.…”

Structure and integrity of fish assemblages in streams associated to conservation units in Central Brazil

“…The presence of the exotic species P. reticulata, tolerant to hypoxia and detritivorous species (Casatti et al, 2009), is strongly correlated with variables of degraded habitats, primarily associated with streams siltation. In extremely impacted stretches, this species is able to hold more than 50% of fish fauna abundance (Casatti et al, 2006a(Casatti et al, , 2006bCunico et al, 2006;Casatti et al, 2009). Fitzgerald et al (1998), studying Canadian impacted streams, suggests that changes in structure of fish assemblage and replacement of species do not happen immediately and may take many years.…”

“…The four P. reticulata individuals sampled only during the wet season in sample units 4 (middle Ribeirão do Gama) and 5 (Córrego Mato Seco), showed that the species is not well established in the area yet, but it's starting to colonize some stretches, especially those with low habitat quality. Other species, such as G. carapo and H. ancistroides, sampled in stretches 4 and 5, are also reported as common in degraded habitats, especially due to their tolerance to hypoxia (Cunico et al, 2006;Casatti et al, 2009). According to Casatti et al (2006b), K. moenkhausii can also be benefited by siltation, mainly by its preference for habitats with particulate substrate (i.e., silt and sand) due to its generalist feeding habit.…”

Influence of environmental variables on stream fish fauna at multiple spatial scales

“…The relationship between P. reticulata and altered waters is documented extensively. This small-sized species has high reproductive capacity and exploits a wide variety of food resources (Koch et al, 2000;Cunico et al, 2006), persisting in highly altered systems (Araújo, 1998;Lemes & Garutti, 2002). Another species adapted to the adverse conditions of urban streams is R. quelen.…”