Histopathological changes and presence of rodlet cells in different organs of common finfish Liza tade in brackish water of the Chilika Lagoon

Chilika Lagoon, the largest brackish water lagoon in Asia, is a prominent biodiversity hotspot along the Indian east coast. Heavy metals can be accumulated by marine organisms like finfish (Liza tade) through a variety of pathways. A specific type of cells called rodlet cells are found in teleosts, either in fresh or marine fishes, as an endogenous cell. The aim of these studies was to examine the localization of rodlet cells in organs of finfish exposed to heavy metals in a brackish water environment. We analyzed the essential (Cu, Zn) and non-essential (Cd, Pb) trace metals and studied the existence of rodlet cells in kidney, brain eyes and gills of Liza tade collected from three different sites (Kalupadaghat, Balungaon, and Keshapur) of Chilika lagoon by microscopic observations. The tissue samples were prepared from gills, kidney, brain and eyes of the finfish for heavy metal analysis by AAS (Perkin Elmer, Model 5000). The metal concentration of analyzed elements (Cd, Zn, Cu and Pb) was highest in the gills (0.53, 0.59 and 0.43 µg/g) for Kalupadaghat. The histological sections collected from intact gill, kidney, brain and eye of Liza tade were observed microscopically for existence of rodlet cells due to pollution. Trace metals content was detected in the organs like gill, kidney, brain and eyes and morphology was found to be normal. The present findings state that heavy metal pollution induces stress in fishes with presence of rodlet cells in the histological characteristics of vital organs like gills and kidney.Highlights• Analyses of water quality of Chilika Lagoon suggests need for necessary actions to prevent decay of coastal ecosystem with all its genetic diversity.• The measurement of heavy metals in fish tissues for health risk calculations showed that consumption poses no threat for the population.• Histopathological changes in gills, kidney, brain and eyes varied based on the heavy metal pollution load.The occurrence of rodlet cells in the gills and kidney of finfish shows its special function as biomarkers of exposure to contaminants.