Springer Science and Business Media LLC

Toxic effects of penoxsulam herbicide on acetylcholinesterase, thiobarbituric acid-reactive substances and protein carbonyl were studied in silver catfish (Rhamdia sp.) and carp (Cyprinus carpio). Acetylcholinesterase activity was inhibited in both brain and muscle tissue, with the inhibition being greater in carp than in silver catfish. The levels of malondialdehyde (MDA), an indicator of lipid peroxidation, decreased in silver catfish brain tissue, but increased in the carp brain. MDA also increased significantly in muscle tissue of silver catfish. The levels of protein carbonyl, another measure of oxidative damage, increased in the brain of both fish species, and in the muscle of carp. However, silver catfish exhibited a decrease in muscle protein carbonyl. It appears that silver catfish may possess better mechanisms of defense against penoxsulam toxicity than carp.

Vegetation reconstruction was widely adopted for the waste slag site. But the toxic elements may be made public from slag due to the organic acid secreted by plant roots, which will pollute the surrounding environment and harm human health. The purpose of the study was to evaluate the harm of toxic substances released from zinc (Zn) smelting waste slag to zebrafish. The effect was simulated by adding organic acid to slag, and the toxicity of the slag was evaluated through the enzyme activity, genetic toxicity, tissue sections of zebrafish liver tissue. The results showed that more heavy metals were made public from the slag, as the concentration of organic acids increased. Exposure to toxic substances for 14 days, the antioxidant enzyme activities, termed as superoxide dismutase (SOD) and catalase (CAT), were significantly affected, which caused obvious malondialdehyde (MDA) accumulation. A comet assay revealed dose-dependent DNA damage in hepatocytes. Depending on the histopathological analysis, atrophy and necrosis of cells and increased hepatic plate gap were observed. The obtained results highlighted that toxic substances from slag may be deleterious to zebrafish.

Metal accumulation in various tissues of Heteropneustes fossilis exposed to the effluent generated from an open cast coal mine was investigated. The contents of Fe, Mn, Cu, Zn, Ni, Pb, Cd and Cr in the effluent were above the permissible limits as suggested by the different pollution control agencies. Out of the eight metals investigated, accumulation (mg kg−1 dry weight of tissue) of Fe was maximum in every tissues followed by liver (265.88 ± 49.89) > kidney (153.0 ± 65.85) > gills (50.66 ± 23.923) > brain (49.303 ± 5.11) > air breathing organs (27.98 ± 10.93) > skin (19.56 ± 2.53) > muscles (8.74 ± 0.83). This was succeeded by Pb in brain (39.35 ± 5.79), Zn in kidneys (27.04 ± 2.31), Mn in the gills (20.69 ± 3.044), Cu (12.53 ± 1.01) > Cr (5.10 ± 2.87) in liver and Cd in kidneys (2.18 ± 0.084). Liver and ABOs showed significant uptake of all the metals. Except Cu and Cr, accumulation of most of the metals by kidneys and gills were also significant. Accumulation of Fe, Cd, Pb and Cr in most of the tissues of exposed fish were above the permissible limits indicating their potential hazardous impact on fish as well as on fish consumers. Even in the tissues of untreated fish the concentrations of Fe (12.26–428.47), Cd (0.2–1.22), Pb (0.02–9.42) and Cr (1.14–11.05) were above the permissible limits. This clearly demonstrates greater bioavailability of these metals in the area.

Fish mediate many biological processes by olfaction, which can be impaired by contaminants (i.e. metals). While the olfactory recovery of fish from metal contaminated lakes if subsequently cultured in clean water has been shown at the neurophysiological level, the recovery potential of olfactory mediated behaviours remains unknown. To study behavioural recovery of fish from metal contaminated lakes, wild yellow perch (Perca flavescens) were collected from two metal-contaminated lakes (Ramsey and Hannah lakes) in the metal-mining district of Sudbury, ON, Canada and cultured in clean water from a reference lake (Geneva Lake) for another 24 h. Olfactory mediated behaviours of the test organisms were tested using avoidance responses to conspecific skin extract. While olfactory mediated behaviours of fish from Ramsey Lake (low contamination) recovered after 24 h in clean water, recovery could not be observed in fish from Hannah Lake (high contamination). These results demonstrate that the recovery of behavioural deficits of fish from metal contaminated lakes is depending on the habitats’ metal concentration.