Effects of abiotic variables on the distribution of fish assemblages in streams with different anthropogenic activities in southern Brazil

Abstract

Studies on fish assemblages in streams point out, that understanding the relationship between species and their environment is crucial for conservation. The present study aimed at evaluating the effects of changes in abiotic variables on the composition and structure of fish assemblages in Neotropical urban streams from southern Brazil with different levels of urbanization. The composition and structure of fish assemblages showed significant differences along the urbanization gradient observed in the streams. Tolerant and non-native species were found in more urbanized sites. A matrix correlation revealed a relationship between abiotic variables and the spatial pattern of structure and composition of fish assemblages. Abiotic variables, such as total phosphorus, dissolved oxygen, and conductivity, determined the distribution of fish assemblages. Streams without urban influence exhibited intrinsically low species richness, suggesting that they are highly susceptible to species loss and diversity reduction. Thus, changes in water quality or hydrological conditions induced by urbanization may intensify these impacts.Estudos sobre as assembleias de peixes em riachos têm enfatizado que a compreensão da relação entre as espécies e seu ambiente é crucial para a conservação das espécies. O objetivo deste estudo foi avaliar os efeitos de alterações nas variáveis abióticas sobre a composição e estrutura das assembleias de peixes em riachos urbanos com diferentes percentuais de urbanização no Brasil. A composição e estrutura das assembleias de peixes mostraram diferenças significativas ao longo do gradiente de urbanização dos riachos. Espécies tolerantes e não-nativas foram encontradas em locais mais urbanizados. A análise de correlação de matrizes indicou uma relação entre as variáveis abióticas e do arranjo espacial da estrutura e composição nas assembleias de peixes. Variáveis abióticas, tais como fósforo total, oxigênio dissolvido e condutividade, determinaram a distribuição das assembleias de peixes. Riachos sem influência urbana exibem naturalmente baixa riqueza específica, sugerindo ser suscetíveis à perda de espécies e redução da diversidade. Assim, mudanças induzidas pela urbanização na qualidade da água ou no regime hidrológico podem exacerbar esses impactos.

Ichthyofauna of streams from the lower Iguaçu River basin, Paraná State, Brazil

“…can be considered high, especially if evaluated some issues: (i) the number of species recorded for other water bodies with similar size in the Neotropics (Bertaco 2009, Couto & Aquino 2011, Marceniuk et al 2011, Oyakawa & Menezes 2011, Cetra et al 2012, Daga et al 2012, as well in other streams in the Paraná State (Araújo et al 2011, Delariva & Silva 2013, Gubiani et al 2010; (ii) the proportion of species registered herein represents 37.7% of the total number of species recorded for the Iguaçu River basin (106 spp. ), including those observed in the main channel of the river .…”

“…Rapid population growth leads to urban sprawl and expansion of agriculture increasingly closer to freshwater environments, affecting negatively the physical and biological structure of these environments (Cunico et al 2006, Pereira et al 2014. In this way, besides the threat that human activities cause, there are few studies on streams in the Paraná State (Pavanelli & Caramaschi 2003, Cunico et al 2006, Galves et al 2007, Araujo et al 2011, Daga et al 2012, Delariva & Silva 2013. In the Iguaçu River basin, stand out the studies conducted in the upper reach of the basin , Vitule & Abilhoa 2003 and surveys of species in streams of the lower Iguaçu River , Bifi et al 2006.…”

Update on the ichthyofauna of the Piquiri River basin, Paraná, Brazil: a conservation priority area

“…Poecilia reticulata has been widespread worldwide as an ornamental animal and mosquito larvae control agent (Dussalt & Kramer 1981, Azevedo-Santos et al 2016). This species is considered to be one of the most abundant in rural and urban streams at present (Oliveira & Bennemann 2005, Pereira et al 2014) likely because of its high resistance and resilience (Gomiero & Braga 2007, Daga et al 2012 in addition to its high competitive efficiency against competition from invasive and native species (Pompeu & Alves 2003).…”

Diet and ecomorphological relationships of an endemic, species-poor fish assemblage in a stream in the Iguaçu National Park

“…These particularities call attention to this fish assemblage, especially outside the area of the INP, where the intensification of hydropower, agricultural and industrial activities has posed serious risks of extinction for their species (Nogueira et al, 2010;Daga et al, 2012). However, singular fish communities such as those in the Iguaçu basin, especially those from streams that are still relatively well preserved, provide a good model to test hypotheses and identify patterns of trophic and ecomorphological structure.…”