Metals and histopathological alterations in the liver of Schizothorax niger, Heckel from the Dal Lake of Kashmir Valley

Abstract

The study was conducted to evaluate the presence and subsequent effect of trace metals (copper, zinc,
iron and manganese) on the histomorphology of liver of Schizothorax niger (endemic fish) from Dal lake
of Kashmir Valley. Using Atomic Absorption Spectrophotometry, the varied seasonal metal
concentrations for copper (66.77  3.12 to 81.68  3.51 ppm), zinc (73.81  2.52 to 97.84  4.62 ppm), iron
(204.92  5.21 to 296.51  4.37 ppm) and manganese (01.13 0.02 to 08.30  1.00 ppm) were observed in
the liver of hosts during the study period of two years. The highest concentration of metals was
observed in the summer seasons and the lowest concentrations in the winter seasons during the entire
study period. Further, histochemical analysis was done to crosscheck the presence of different metals
in the tissue sections of liver of S. niger. The subsequent effects of metals was demonstrated
histologically using haematoxylin and eosin stain that showed disruption of the hepatic cords and
tubules with congestion and degenerative changes in hepatocytes that varied from mild in winter
seasons to severe vascular degeneration in summer season. From the present study it may be
concluded that the metals in the environment are polluting the water bodies and their subsequent
deleterious effects harm the aquatic fauna particularly the sensitive native fish, S. niger which is one of
the reasons for its decline from the fresh water resources of the Kashmir Valley.