Effects of deforestation on fish community structure in Ecuadorian Amazon streams

Abstract

SUMMARY 1. There is little information on the impacts of deforestation on the fish fauna in neotropical streams, and on parameters influencing species diversity and community structure of fish. We analysed these aspects in 12 stream sites in the Ecuadorian Amazon. The stream sites represented a large gradient in canopy cover and were located in an area of fragmented forest. While some streams had been deforested, they had not suffered gross degradation of the habitat. 2. The species richness of stream fish was not related to deforestation. Local fish diversity (Fisher's Alpha) was positively related to the surface area of stream pools (m2). Beta diversity was higher among forested than deforested sites, indicating greater heterogeneity in species composition among forested than deforested sites. The percentage of rare species was positively correlated with canopy cover. 3. Total fish density increased with deforestation, and the fish community changed from dominance by omnivorous and insectivorous Characiformes at forested sites to dominance of periphyton‐feeding loricariids at deforested sites. 4. Multidimensional statistical analysis of fish community structure showed that six environmental variables (the area of stream bottom covered by leaves, relative pool area, particulate organic matter, mean depth, conductivity and suspended solids) were related to the ordination axes. The presence of leaves, which was strongly correlated to canopy cover, was the variable most closely related to fish community structure, while relative pool area was the second strongest variable. Thus, fish community structure was strongly affected by deforestation.

Dietary-morphological relationships in fish assemblages of small forested streams in the Bolivian Amazon

“…Invertivorous species composed the dominant guild of this assemblage. This result is in agreement with the ones already obtained for other tropical (Angermeier and Karr 1983;Bojsen and Barriga 2002;Silva 1993;Uieda et al 1997;Deus and Petrere-Junior 2003;Pouilly et al 2006;Ibanez et al 2007) and temperate forested streams (Schlosser 1982;Rahel and Hubert 1991;Oberdorff et al 1993Oberdorff et al , 2002 suggesting a possible convergence in trophic structure between temperate and tropical fish assemblages ). Trophic diversity of fish assemblages in such systems may be strongly related to food availability (Angermeier and Karr 1983), which in turn may be influenced by common environmental constraints.…”

Diet of Astyanax paranae (Characidae) in streams with different riparian land covers in the Passa-Cinco River basin, southeastern Brazil

“…However, abundance and biomass of this species in streams of the Corumbataí River basin were lower in streams with grassland coverage in comparison to forested streams (Anderson Ferreira, unpublished data). The absence of riparian forest influences not only the structure (abundance, richness and diversity) of fish assemblages in streams, but may also lead to changes in trophic structure of fish fauna (boJsen & barriGa, 2002;lorion & Kennedy, 2009;Ferreira et al, 2012).…”

Ictiofauna do Ribeirão Limoeiro, Bacia do Rio Cachoeira, BA

“…Vários autores têm associado o aumento da diversidade ao longo do rio com o aumento da heterogeneidade de hábitats (Langeani et al 2005), o qual, por sua vez, é relacionado principalmente a um aumento na vazão e na disponibilidade de abrigos (Garutti 1988, Uieda & Barreto 1999, Braga & Andrade 2005, Cetra & Petrere Jr. 2006. Como sugerido por Bojsen & Barriga (2002), a relação positiva entre a riqueza de espécies e tamanho do hábitat não é somente associada com o esforço amostral. No Ribeirão Limoeiro pôde-se verificar que a riqueza, diversidade e equabilidade aumentaram em direção à jusante, sendo significativamente maior no ponto P3 em relação aos demais pontos amostrados, coincidindo com resultados encontrados por Abes & Agostinho (2001) onde a riqueza, diversidade e equabilidade aumentaram em direção aos segmentos inferiores.…”