Bioassays in assessment of genotoxicity and toxicity of freshwater bodies

Abstract

Untreated urban wastewaters impose high pressure on receiving water bodies. Pollution pressure may triger a cascade of events in exposed organisms, affecting different levels of biological organisation. Fish are a widely used group of bioindicators in ecogenotoxicological studies, due to their position in the aquatic trophic web and role in human nutrition. In this work, chub (Squalius cephalus) and bream species (Abramis brama, Blicca bjoerkna, Ballerus sapa) were monitored at reservoirs, Uvac and Garasi, and rivers: Dunav, Sava, Pestan, and Beljanica. Analysis of metals and metalloids in liver, gills, gonads, and muscle was performed by ICP-OES and used as a biomarker of accumulation. The single cell gel electrophoresis, comet assay, was used to assess DNA damage level in blood, liver and gills, as a biomarker of exposure. Histopathological alterations were monitored in liver and gills of breams from the Sava and Danube Rivers, as a biomarker of effect. Analysis of the accumulation of metals and metalloids in different tissues showed a high level of differentiation, as well as significant differences in tissues distribution of elements between the studied sites. The highest concentrations of metals and metalloids were present in gills, liver and gonads, and the lowestin muscle. Uvac showed the highest quality of water which was confirmed by the low values of DNA damage in all tissues compared to the other sites. In chub, blood showed the lowest level of DNA damage compared to liver and gills, while in all bream species DNA damage was the highest in blood cells, following gills and liver. Histopathological analysis of breams showed a higher degree of alterations in liver compared to the gills. This study highlighted the importance of the multiple biomarkers approach in obtaining information about the response of biota to pollution by analyzing changes at different levels of biological organization.