Bioindication of cardboard-paper mill effluents using molecular responses of fish Carassius auratus and bivalve mollusk Unio tumidus

Abstract

The effluents of cardboard-paper mill (CPM) industry belong to most abundant pollutants of surface water. The aim of this study was to elucidate the toxicity of effluents downstream the CPM by the bioindication. The specimens of fish Carassius auratus (Cyprinidae) and mollusk Unio tumidus (Unionidae) from the suspected polluted area (SP) and pristine area as control (C) were compared. The fish and mollusk from SP demonstrated plural signs of toxicity and stress: 2.5−3.7 times higher levels of DNA fragmentation, nuclear abnormalities, lipid peroxidation products and lipofuscin (determined only in fish) in comparison with C-groups. The exposure to the certain xenobiotics was confirmed by the elevated by 2−3 times levels of metallothionein (response to toxic metals), CYP450-related activity and vitellogenin-like proteins (responses to endocrine disrupters, in particular, chlorinated organic substances). Cholinesterase activity in the brain of fish was the same in the C- and SP-groups proving the low evidence of typical agricultural pollution. Chemical analysis of water confirmed the highest level of pollution by phenols, chlorine, sulphate, nitrogen and organic compounds only directly downstream the wastewater treatment facilities of the CPM. These results prove the molecular bioindication to be the most valid approach to assess the toxicity of CPM effluents.