Bioaccumulation and ultrastructural alterations of gill and liver in Asian sea bass, Lates calcarifer (Bloch) in sublethal copper exposure

Abstract

Bioaccumulation and ultrastructural alterations in gill and liver tissues of 3-month old Asian sea bass, Lates calcarifer, in response to copper were studied by transmission electron microscopy (TEM). Fishes were exposed to two sublethal concentrations of copper (6.83 ppm and 13.66 ppm) for a period of 28 days. Accumulation of copper were higher in the liver followed by gills. The damaging effects of the histoarchitecture of gill tissues in coper-exposed sea bass were hypertrophy and hyperplasia of epithelial cells, severe oedema, telangiectasia and secondary lamellar fusion. In addition extensive vasodilation with stretching and necrosis of pillar cells were also noted. The liver showed hydropic swelling of hepatocytes with nuclear pyknosis and chromatin condensation. Blood congestion in sinusoids and accumulations of lipid droplets in the hepatocytes at higher concentrations were observed.