Liver lesions in the gar fish (Lepisosteidae) as biomarkers of exposure

The objective of this research was to identify lesions and diseases in fish as biomarkers of exposure to environmental contaminants from polluted wetlands typical of the Mississippi River Basin. Devilʹs Swamp, located northwest of Baton Rouge, Louisiana, is an ecosystem contaminated with a variety of metals and organic chemicals. The nearby control site was Tunica Swamp. Gar were collected from the study sites by electroshocking and crab trap. The fish were necropsied and evaluated for disease and histopathology, and tissues were analyzed for metals and organics typical of Devilʹs Swamp contaminants. Liver lesions occurred in three species of gar (Lepisosteus osseus L. oculatus) and L. platostomus). The striking liver lesions observed in gar from Devilʹs Swamp were abundant melanin-rich macrophage centers, pancreatitis and perivascular cuffing, and ductal proliferations in the exocrine pancreas. Other lesions observed were parasitism, inflammation and multifocal necrosis. Image and pigment analyses of melanomacrophage centers (MMC) in L. Oculatus (spotted gar) indicated increased levels of hepatocellular and MMC iron, and larger MMC may be due to significant body burdens of pollutants.