Fish assemblage structure and aquatic pollution in a Brazilian stream: some limitations of diversity indices and models for environmental impact studies

Abstract

– The aim of this study was to describe and quantify the effect of aquatic pollution on the fish assemblage structure of the Corumbataí River (Brazil), by comparing two sites with different water quality characteristics. The results revealed that abundance of individuals was low at the polluted site (B). However, the two sites did not differ significantly in species richness (total and average). This fact contradicts theories stating that portions where the transverse area of the channel is larger should present a higher biological richness. It was also observed that the ichthyofauna of site B had higher evenness, and, consequently, a tendency to a higher diversity than that at site A. This demonstrates that diversity estimates should be used cautiously in environmental impact studies, as they do not necessarily indicate better conditions of communities living in more preserved environments.

The effects of press and pulse disturbance by long and short-term pollution on the fish community in the Sinos River, RS, Brazil

“…Richness increased in all sites by approximately the same amount and mean Shannon diversity values followed this tendency. An increase in species richness can be a community response to decreasing impact levels (Soto-Galera et al, 1998;Lima-Junior et al, 2006). However, increasing impact levels which occur when an aquatic system shifts from almost pristine to very moderately impacted, may also increase species richness due to slightly higher nutrient input and, consequently, higher primary and secondary production (Mackey and Currie, 2000).…”

Prioritization of fish assemblages with a view to conservation and restoration on a large scale European basin, the Loire (France)

“…The main causes are habitat destruction and defragmentation (Cuizhang et al 2003), exotic species introduction (Saunders et al 2002;Copp et al 2005), and global climate change impacts (Cuizhang et al 2003;Lévêque et al 2005). Aquatic ecosystems are particularly concerned by the loss of biodiversity (Ricciardi and Rasmussen 1999;Gibbs 2000;Saunders et al 2002;Dawson et al 2003), especially due to the increase in irrigation needs, industries and private use (Szöllosi-Nagy et al 1998) but also due to pollution (Lima-Junior et al 2006). Freshwater fish are one of the most threatened taxonomic groups (Darwall and Vié 2005) because of their high sensitivity to the quantitative and qualitative alterations of aquatic habitats Oberdorff et al 2002).…”

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

“…On the other hand, in undisturbed aquatic environments a greater fish richness and a relatively evenly distributed species abundance is expected (Magurran & Phillip, 2001), both favored by the complexity and heterogeneity of the aquatic environment (Gorman & Karr, 1978;Tonn & Magnuson, 1982;Horan et al, 2000;Lima-Jr. et al, 2006). Furthermore, it was seen that fish species diversity is high in undisturbed water courses with riparian vegetation cover, because they present a greater availability of habitats, low oscillation of environmental conditions (Wichert & Rapport, 1998;Stauffer et al, 2000;Vondracek et al, 2005;Gomiero & Braga, 2006) and availability of fish food, such as aquatic insects (Winemiller et al, 2008).…”