Temporal variation in fish composition and abundance in a perennial tributary of the rio Paraguaçu, a little-known drainage in the Brazilian semi-arid region

Abstract

The rio Santo Antônio is a perennial lowland stream in the Brazilian semi-arid region, and is the main tributary of the upper rio Paraguaçu, an important drainage of the Chapada Diamantina. The temporal variation of the fish composition and abundance in a stretch of the middle course of the river was evaluated. Sampling was carried out monthly between August 1998 and July 1999, using standardized gear and techniques. Data on water and air temperature, water transparency, maximum and mean depth, width and area of the channel, and flow were recorded on each fish sampling occasion. Univariate and multivariate statistical analyses were employed in order to detect significant temporal differences in environmental parameters and fish abundance. Temperature, transparency and channel depth drove opposite tendencies between the dry and rainy months. The fish community richness (32) and composition did not change between these periods, but large fish caught with gillnets were more abundant in the rainy months. We conclude that the undramatic disturbance in the hydrological stream conditions between the dry and rainy periods led to weak responses of the fish assemblage. Long-term monitoring would be necessary, however, to assess the real persistence of the fish community structure in this perennial stream.

Effects of conservation status of the riparian vegetation on fish assemblage structure in neotropical headwater streams

“…Studies as (Lowe-McConnell, 1999;Fernandes et al, 2009) observed contrasting communities between seasons in tropical headwater streams. However, Mazzoni et al (2006) and Santos & Caramaschi (2011) found that the abundance of a few small species are related to temporal variations in the hydrologic regime. Therefore, it is difficult to observe a general pattern of fish communities composition (Novakowski et al, 2008).…”

A ictiofauna da bacia do rio Sarapuí, SP, Brasil: estrutura das assembleias e a influência da sazonalidade

“…Neste estudo, setembro/2010 apresentou as médias mais baixas de temperatura, bem como a menor riqueza e abundância de espécies. Santos & Caramaschi (2011) também verificaram diferenças na temperatura entre a época seca e chuvosa, sendo esta variável uma das que mais correlacionaram com abundância dos peixes. Em rios tropicais a comunidade de peixes é afetada pelas mudanças sazonais, já que esta expande o ecosistema aquático da época seca para a chuvosa (Santos & Caramaschi, 2011).…”

“…Santos & Caramaschi (2011) também verificaram diferenças na temperatura entre a época seca e chuvosa, sendo esta variável uma das que mais correlacionaram com abundância dos peixes. Em rios tropicais a comunidade de peixes é afetada pelas mudanças sazonais, já que esta expande o ecosistema aquático da época seca para a chuvosa (Santos & Caramaschi, 2011). Variações na abundância em decorrência da sazona lidade podem refletir mudanças na estrutura da assembleia de peixes.…”

“…Uma forma possível para superar a síndrome do rio urbano é gerenciar a saúde do rio de forma eficaz através da compreensão das interações de fatores antrópicos e naturais, particularmente por meio de um programa de monitoramento de custo-benefício bem planejado. Distúrbios antrópicos incluem canalização, barragens, remoção da vegetação ripária, lançamento de esgoto e a presença de espécies invasoras (Santos et al, 2011).…”

Environmental typology of rivers from the Brazilian semiarid as a first step for the application of the index of biotic integrity: The case of the Chapada Diamantina

“…From the 19th century until the 1980s, the rivers of the Chapada Diamantina were impacted by mechanized diamond mining and this exploration resulted in drastic changes in the riverbeds and banks due to burning the vegetation and soil excavation. At present, the main impacts are related to the deforestation and unregulated tourism activities (Santos & Caramaschi, ). Notwithstanding the importance and the high incidence of different types of environmental degradation, no studies on the environmental quality of the rivers have been carried out.…”