High concentrations of metals in the waters from Araguari River lower section (Amazon biome): Relationship with land use and cover, ecotoxicological effects and risks to aquatic biota

Bioaccumulation of metals and genotoxic effects in females of Colomesus asellus collected in an Amazon River estuary, Amapá, Brazil

“…The percentage of nuclear alterations was calculated by the ratio between the total number of altered erythrocytes and the total number of observed erythrocytes, followed by multiplying the product of this ratio by 100. To calculate the genotoxicity index, all nuclear changes identified in fish samples were grouped, followed by calculating the ratio between the total number of altered cells and the total number of cells observed and then multiplying this ratio by 100 (Viana et al, 2021).…”

“…The occurrence and increase in the frequency of genotoxic damage in fish erythrocytes are a function of the sum total of pollutants to which fish are exposed in the aquatic environment related to the sum of the action of pollutants existing in the aquatic environment (Azevedo-Silva et al, 2016, Calado et al, 2020. The nuclear alterations observed in the erythrocytes of C. asellus females constitute evidence of the existence of genotoxic contaminants in the waters of the "Pedrinhas Channel", which is located at the mouth of the Amazon River (Viana et al, 2021). Gomes-Silva et al (2020) pointed out that the presence of genotoxic contaminants in water impairs the interaction between DNA molecules and nuclear proteins during cell division, resulting in changes in the nuclear morphology of fish erythrocytes.…”

“…Gomes-Silva et al (2020) pointed out that the presence of genotoxic contaminants in water impairs the interaction between DNA molecules and nuclear proteins during cell division, resulting in changes in the nuclear morphology of fish erythrocytes. Using the model fish Danio rerio, Viana et al (2021) investigated toxic and genotoxic effects associated with metals present in water samples collected from the Araguari River, a tributary of the Amazon River. In comparison to the results obtained by Viana et al (2021), the species C. asellus showed greater genetic damage in erythrocytes, mainly from nuclear invagination, nuclear budding and lobulated nucleus.…”

“…Using the model fish Danio rerio, Viana et al (2021) investigated toxic and genotoxic effects associated with metals present in water samples collected from the Araguari River, a tributary of the Amazon River. In comparison to the results obtained by Viana et al (2021), the species C. asellus showed greater genetic damage in erythrocytes, mainly from nuclear invagination, nuclear budding and lobulated nucleus. The comparison also revealed higher genotoxicity index for C. asellus.…”

“…Tuzuki et al (2017) reported that Mn induced genotoxic effects, including DNA strand breaks, in fish erythrocytes. For nonessential metals, such as Pb, Hg, Cd and Cr, several studies have reported their genotoxic potential in fish, even when present in low concentrations in the aquatic environment (Pereira et al, 2016, Ali et al, 2020, Viana et al, 2020, Viana et al, 2021. Sá-Oliveira et al (2016) emphasized that the edge of the city of Macapá, bounded by banks of the Amazon River, is subject to different types of anthropogenic impacts and stress, especially the discharge of improperly treated urban waste.…”