ACUTE EFFECTS OF MERCURIC-CHLORIDE ON THE OLFACTORY EPITHELIUM OF TRICHOMYCTERUS-BRASILIENSIS

The olfactory organ in fish has a distinct localization, a major biolo gical significance, and an important role in fish behavior. One group of Trichomycterus brasiliensis was exposed to two different concentrat ions of mercuric chloride (0.05 and 0.1 mg HgCl2 liter(-1)). The surfa ce of the olfactory epithelium was investigated with scanning electron microscopy. Forty individuals were used in this study. The olfactory epithelia were collected after 4, 12, 24, 48, and 96 hr from contamina ted and control aquaria. In the experiment with 0.1 mg HgCl2 liter(-1) all individuals died within 24 hr with significant damage to the olfa ctory epithelium. Type 1 ciliated cells were the most evidently altere d. With 0.05 mg HgCl2 liter(-1) the initial alterations were considera ble, but after 96 hr the epithelial surface recovered its initial appe arance compared with the control individuals. This recovery is due to the resistance of this species and to the decrease in the Hg2+ concent ration in water. Therefore, the alterations observed in this study rev eal that inorganic mercury affects the olfactory organs structurally, with evident interference with normal behavior. (C) 1995 Academic Pres s, Inc.