Abstract
Located in southern Brazil, the Pampa biome has been under constant threat due to improper management of human effluents and use of pesticides. These contaminants accumulate mainly in water resources resulting in chronic poisoning of aquatic biota. Up to date, no studies on the assessment of environmental quality in the Brazilian portion of Pampa biome have been undertaken. Thereby, our main goal in this study was to investigate the ecotoxicological risks caused by human activity in the Santa Maria River, a major water course in the Brazilian Pampa biome. Brain and muscle tissues were used for determining oxidative stress and cholinesterase biomarkers in fish (Astyanax sp.) exposed to urban and agricultural effluents. A substantial decrease in fish muscle acetylcholinesterase activity was observed in exposed animals, compared to controls (kept under laboratory conditions). In parallel, increased lipid peroxidation and significant changes in stress-responsive antioxidant enzymes (GST, CAT, GPx, and TrxR) were detected. In the fish brain, a significant increase in GST activity is reported. In conclusion, our results showed significant changes in biomarkers of water contamination in Astyanax captured in Santa Maria River, pointing to important levels of water pollution in the region and validating the use of Astyanax in biomonitoring programs within the Pampa biome borders.
Highlights
Pampa biome, located in southern Brazil, covering approximately 2% of the national territory and 63% of the Rio Grande do Sul State comprehend a large grasslands area containing a vast number of endemic species [1]
The remaining supernatant was centrifuged at 20,000 g for 30 minutes at 4∘C to determine the activity of antioxidant enzymes, glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), and thioredoxin reductase (TrxR)
There were no significant differences in thiobarbituric acid reactive substances (TBARS) and hydroperoxides in the brain of captured animals compared to control (Figure 2(d))
Summary
Pampa biome, located in southern Brazil, covering approximately 2% of the national territory and 63% of the Rio Grande do Sul State comprehend a large grasslands area containing a vast number of endemic species [1]. The Brazilian Pampa biome is poorly studied, comparing to other five Brazilian biomes [2]. This biome has been constantly threatened due to urban and agroindustrial growth [2] which releases a large amount of pollutants in its water sources. Despite such situation, no studies concerning the impacts of the human activities on the Pampa ecosystem were undertaken so far. Thereby, biochemical changes are considered as early responses to contaminants, occurring before death or manifestation of diseases and can be used as biomarkers for the detection and monitoring of such compounds [5]
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