Changes in the structure of fish assemblages in streams along an undisturbed-impacted gradient, upper Paraná River basin, Central Brazil

Abstract

The João Leite River is located in the upper Paraná basin, Central Brazil. It drains areas covered by Cerrado vegetation interspersed with urban and agricultural areas. This study aims to asses changes of the fish assembleges structure along a undisturbed-impacted gradient in ten stream stretches using ecological descriptors, a similarity index and the abundancebiomass relationship (ABC curves). The fish were collected during the dry period using electrofishing gear in stretches of 50 m. Results show that the environmental variation observed along the undisturbed-impacted gradient considered influences on fish assemblage structure. Both richness and diversity differences between fish assemblages are partially influenced by stream stretch orthonian order and anthropogenic impacts. ABC curves classified six stream stretches located in preserved or impacted areas as undisturbed while four stretches were classified as disturbed. This is attributed to the influence of the undisturbed habitat within the conservation unit and the presence of K-or r-strategist species. This type of study contributes to an understanding of the effects of aquatic environment conservation on the Brazilian Cerrado core area, where the choice of conservation areas prioritizes terrestrial over aquatic aspects.O ribeirão João Leite está localizado no alto da bacia do rio Paraná, Brasil Central, onde drena áreas cobertas por vegetação tipo Cerrado intercaladas com áreas urbanas e agrícolas. Este estudo objetiva avaliar as mudanças na estrutura das assembleias de peixes ao longo de um gradiente ambiental (não perturbado-impactado) em trechos de dez riachos utilizando descritores ecológicos, um índice de similaridade e a relação abundância-biomassa (curvas ABC). Os peixes foram coletados durante o período da estiagem em trechos de 50 m utilizando a pesca elétrica. Os resultados indicam que a variabilidade ambiental observada ao longo do gradiente considerado influencia na estrutura das assembleias de peixes. As diferenças observadas entre a riqueza e diversidade das assembleias de peixes são parcialmente influenciadas pela ordem do riacho e os impactos antropogênicos. As curvas ABC classificam seis trechos localizados em áreas preservadas ou impactadas como não perturbados e quatro como perturbados. Isto é atribuído à influência do habitat preservado presente na unidade de conservação e à presença de espécies com estratégias K-ou r-. Este tipo de estudo contribui ao entendimento dos efeitos da conservação do ambiente aquático na área central do Cerrado brasileiro, onde as escolhas de áreas de conservação dão prioridade aos aspectos terrestres em detrimento dos aquáticos.

Ichthyofauna as an environmental quality indicator of the Bertioga Channel, São Paulo (Brazil)

“…This is important since pristine areas for comparison are absent in the vicinities. Several authors agree that the ABC analysis should be used in combination with other methods to access quality of aquatic environments, but this index was applied in Brazilian inland waters (PINTO et al, 2006;FREIRE, 2009;TEJERINA-GARRO, 2010) as well as in coastal estuarine systems (FALCÃO et al, 2008, OTERO et al, 2006, DIAS et al, 2011. Other indices as the Index of Biotic Integrity -IBI (KARR, 1981) were applied in inland waters (PINTO et al, 2006a, b;ARAÚJO, 2007;SCHULZ, 2010).…”

Diet and trophic guilds of fish assemblages in two streams with different anthropic impacts in the northwest of Paraná, Brazil

“…Such sites are associated with riparian vegetation and water quality. Nevertheless, the removal of this type of vegetation or changes in land cover and other artificial anthropogenic changes in these environments may affect streams, which directly affects the fish fauna in with respect to vital processes, such as feeding and reproduction (WALSH et al 2005, DIAS & TEJERINA-GARRO 2010. In this context, CARVALHO & UIEDA (2010) observed significant differences in the input of litter to the aquatic system between forested and non-forested areas.…”

Trophic organization and fish assemblage structure as disturbance indicators in headwater streams of lower Sorocaba River basin, Sao Paulo, Brazil

“…Therefore, the variation was mainly due to differences in in-stream and margin banks variables. This conclusion is based on local habitat conditions and regional factors influence (Hoeinghaus et al, 2007), especially regarding environmental heterogeneity (Casatti et al, 2009;Dias & Tejerina-Garro, 2010). The geographic proximity inserts the four reaches in the same historical, biogeographical and evolutive context, albeit the local environmental impacts are from distinct sources and present different intensities.…”