Fish community response to environmental variations in an impacted Neotropical basin

Abstract

Fish communities' organisation is a challenging task due to global, local and temporal variations related to biotic and abiotic factors, highlighting anthropic activities. The Verde River Basin (VRB) was chosen as a model to the fish community study due to its complexity, presenting a longitudinal gradient of degradation. The ichthyofauna and abiotic factors were sampled during twelve months in four sites. Analyses employed rarefaction curves with Hill numbers estimators and canonical correspondence analysis. The endemic Apareiodon sp. (not described), Hypostomus albopunctatus, H. strigaticeps, Oligosarcus paranensis, Neoplecostomus yapo and Trichomycterus diabolus were associated with structurally complex and well-preserved environments. In contrary, Astyanax aff. fasciatus, Corydoras ehrhardti, Geophagus brasiliensis, H. ancistroides and Phalloceros harpagos showed tolerance to impacted environments. The methods here employed allowed to identify and explain differences in the ichthyofauna structure, distinguishing the influence of spatial, temporal and human effects on the fish communities. K E Y W O R D Sabundance, anthropic impacts, diversity, entropy, lotic system | 1127 SILVEIRA Et AL.

Fish assemblage structure in a Neotropical urbanised prairie stream exposed to multiple natural and anthropic factors

“…with an increase of generalist and tolerant species are observed at the downstream most impacted reaches receiving urban effluents(Da Silveira et al, 2018). Interestingly, our survey showed that urbanisation at upstream reaches could reverse this longitudinal pattern, forcing intolerant species to thrive at the downstream less impacted reaches and favouring tolerant, air breathing species to dominate the upstream impacted reach.…”

“…For instance, a low increase in the urbanisation level has changed the composition and structure of Neotropical stream fish assemblages mainly due to changes in conductivity and concentrations of dissolved oxygen and total phosphorus (Daga et al, 2012). Particularly, a decrease in diversity, abundance, specialists and nektonic species with an increase of generalist and tolerant species are observed at the downstream most impacted reaches receiving urban effluents (Da Silveira et al, 2018). Interestingly, our survey showed that urbanisation at upstream reaches could reverse this longitudinal pattern, forcing intolerant species to thrive at the downstream less impacted reaches and favouring tolerant, air breathing species to dominate the upstream impacted reach.…”

Idade E Crescimento De Peixes De Riacho: Métodos E Desafios Para a Obtenção De Estimativas Robustas

“…Em avaliações de estrutura de comunidades, a abundância por petrechos de pesca tem sido testada (ex. : utilizando testes de Kruskal Wallis, Levene) para direcionar a tomada de decisão sobre agrupar ou não as informações obtidas a partir de diferentes petrechos (Silveira et al 2018). Entretanto, qual amostragem é funcional para estudos populacionais enfocando idade e crescimento?…”

Characterization of the Fish Population in the Southwestern Part of the Onega Lake (Karelia) Based on the Results of Long-Term Monitoring

“…Currently, the relevance of studying the fish population of freshwater lakes prone to anthropogenic impact remains high [1][2][3][4][5][6]. The Onega Lake, the second largest lake in Europe, is valuable in terms of energy, socio-economic, and environmental significance for the development of the North-West of Russia.…”