Water quality assessment of fifth-order tributaries of the reservoir at the Marechal Mascarenhas de Morais Hydroelectric Power Station in the Rio Grande watershed (State of Minas Gerais, Brazil)

Abstract

Aim: This study assessed the water quality from the springs and river mouths of the fifth-order tributaries which compose the reservoir of Marechal Mascarenhas de Morais HPS in the middle Rio Grande watershed, Minas Gerais, Brazil. Methods: It has been studied 14 tributaries distributed in the reservoir, two points for tributary - spring and river mouth. Eighteen limnological variables added to the Rapid Assessment Protocol and Trophic Level Index were evaluated. The benthic macroinvertebrates had been collected by the use of a granulometric sieve and a Petersen-type sampler. Results: The cluster analysis of limnological data revealed the existence of two tributary groups. Group I consisted of eutrophic tributaries degraded by human activities, while group II exhibited good water quality and well-preserved environments. Group I was divided into two subgroups, Ia tributaries were characterized by being altered by human activities, while the Ib subgroup was composed of highly impacted tributaries. By ordering the PCA, it can be observed spatial segregation of groups, where the most polluted tributaries were separated from those which are better preserved. A total of 8,987 individuals belonging to 36 families of macroinvertebrates were identified. The family Chironomidae was the most abundant. There was no significant difference in total abundance and the richness of macroinvertebrates taxa inhabiting springs, by those who inhabiting the river mouths. Conclusions: It was noticed that most of the tributaries which supply and composes the reservoir are already degraded and have low quality water. It is observed that the human presence drastically affected water quality and faunal composition of tributaries. Thus, it is necessary a complementary study of the tributaries in working with issues related to reservoirs, as these components have direct influence on the water quality and composition of these lentic environments.

How the fluctuations of water levels affect populations of invasive bivalve Corbicula fluminea (Müller, 1774) in a Neotropical reservoir?

“…These impoundments are mainly employed for power production, but serve other purposes, such as water sources for irrigation, sources of income and leisure. After implementation, water quality in reservoirs is usually compromised due to eutrophication and other negative effects brought upon by human presence and activity in the surrounding areas, leading to alterations on nutritional load and faunal composition (Andrade et al, 2012).…”

Reservoir management: an opinion to how the scientific community can contribute

“…The subsequent environmental indicators are usually measured while monitoring the phytoplankton (Bicudo et al, 2005), zooplankton (Serafim Junior et al, 2011;Matsumura-Tundisi et al, 2015), benthos (Andrade et al, 2012), ichthyofauna (Fernandez et al, 2007;Arcifa & Esguícero, 2012), aquatic macrophyte (Neiff et al, 2000;Bianchini Junior & Cunha-Santino, 2014), sediments and water samples (Espíndola et al, 2004;Smith et al, 2014). The water quality is characterized by physical (temperature, transparency, turbidity, electrical conductivity, oxy-reduction potential), chemical (dissolved oxygen, total solids, nutrients, metals, chemical oxygen demand, a specific elements of interest) and biological variables (coliforms, biochemical oxygen demand, chlorophyll); as well as the water nutrient status (trophic state index -TSI; Carlson, 1977), the water quality index (WQI; Horton, 1965), and other environmental indicators that can be legislated and often used in this type of monitoring.…”