Effects of sub-lethal exposure of cadmium on histopathology of gills of Nile tilapia, Oreochromis niloticus and the mitigating effects of Cladophora glomerata

In this study, Nile tilapia, Oreochromis niloticus kept in the medium with or without green algae, Cladophora glomerata was exposed to sublethal concentrations of 0.1 mg/l and 1 mg/l Cd+2. At the end of 15 and 30 day periods, fish gills were removed to investigate histolopathological alterations by light microscopy. As a result of cadmium application; in the gills, changes were observed such as curling and fusion in secondary lamellae, epithelial hypertrophy, epithelial hyperplasia, pillar cell breakage, edema, swelling, aneurysm, necrosis and increased mucus secretion. The severity of the alterations resulting from cadmium increased with dose-time dependent. Histopathologic effects were observed to be lighter in the groups contained algae. This suggests that algae-like organisms in the environment accumulate some of the cadmium in their bodies, causing fish to be less affected.