ACCUMULATION AND DISTRIBUTION OF INORGANIC MERCURY IN A TROPICAL FISH(TRICHOMYCTERUS-ZONATUS)

Different aspects of mercury accumulation, retention, and elimination in temperate fish species have been reported, but few data are availab le for tropical species, In this work Hg accumulation in Trichomycteru s zonatus, where experimental losses were estimated, was studied, Fort y individuals (males and females) of T. zonatus were acclimatized for 30 days. In each experiment 10 aquaria were used, with 1 fish each (5 exposed to HgCl2 and the others as controls), The concentration tested was 15 mu g Hg . liter(-1) including 18 kBq . liter(-1 203)HgCl(2) as tracer, Fish were dissected and measured for Hg by gamma scintillatio n spectrometry at regular intervals, and after 96 hr were transferred to mercury-free tap water, Approximately 40% of added mercury was lost by volatilization (20%) and adsorption (20%) in 48 hr. A faster absor ption of inorganic mercury was observed initially in gills, a higher a nd lower retention in kidney and muscle, respectively, For T. zonatus the kidney, gills, and liver were considered the critical organs, but this order changed after 98 hr in mercury-free tap water. The distribu tion of inorganic mercury in T. zonatus seems quite similar to that fo und in temperate species, but the sensitivity of this species to Hg se ems higher. (C) 1996 Academic Press, Inc.