Abstract
Brazilian floodplains have suffered great changes in their natural characteristics in recent decades, mainly in the flood pulse. The Upper Paraná River floodplain is one of the few places where are found remained areas in which such peculiar characteristics keep reflecting on its high biodiversity. Ephemeroptera nymphs are one of the higher density groups among benthic community, occurring in many water bodies like large rivers and secondary channels. We sought to understand which factors are needed for the species establishment and how much important is the species colonization, especially in environments with anthropogenic changes. The marginal areas, which are more structured with presence of macrophytes, showed the highest density and richness even in the Paraná River that has great human impact. We verified dominance of Americabaetis alphus, Tricorythopsis araponga, Tricorythopsis artigas on the Parana River, correlated with transparency, depth and electric conductivity, while the dominance of Traverella sp. was correlated with water temperature, especially in marginal areas. Consequently, the increasing transparency and electric conductivity due to the Porto Primavera dam in Parana River can be favoring those Ephemeroptera species. We demonstrated the importance of preserving the wetlands of Ivinhema River State Park mainly for Guajirolus sp., which was only registered in this region. Therefore, our study provides support for understanding gaps from previously studies using artificial substrates in three large rivers which are of great importance to the upper Paraná River floodplain.
Highlights
Environmental laws aiming at surveying, managing and protecting freshwater ecosystems throughout the world rely on biological indicators of ecosystem health (Stoddard et al, 2008; Callisto et al, 2004)
Studies about macroinvertebrate distribution from lotic environments has generated great interest, so that many of the general functional models of stream and river ecology were derived from studies of this fauna (e.g., “River Continuum Concept” – Vannote et al, 1980 and “Serial Discontinuity Concept” – Ward and Stanford, 1983)
Significant differences for richness were observed for river and temporal scales
Summary
Environmental laws aiming at surveying, managing and protecting freshwater ecosystems throughout the world rely on biological indicators of ecosystem health (Stoddard et al, 2008; Callisto et al, 2004). Natural preserved areas keep the integrity of a considerable number of aquatic ecosystems, which makes them of great importance for the maintenance of both biological diversity and structural patterns of these environments (Agostinho et al, 2005). Studies with these ecological perspectives have been conducted to better understand the interactions of organisms and functioning of aquatic ecosystems (Callisto et al, 2001; HenriquesOliveira et al, 2003; Suriano and Fonseca-Gessner, 2004; Silva et al, 2007). Studies about macroinvertebrate distribution from lotic environments has generated great interest, so that many of the general functional models of stream and river ecology were derived from studies of this fauna (e.g., “River Continuum Concept” – Vannote et al, 1980 and “Serial Discontinuity Concept” – Ward and Stanford, 1983)
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