Comparative uptake, bioaccumulation, and gill damages of inorganic mercuryin tropical and Nordic freshwater fish

This paper reports comparative results on the bioaccumulation of inorganic mercury and resulting gill damages in the tropical fish, Trichomycterus zon atus, and a nordic species, Salvelinus alpinus, using radioisotope Hg-203 t echniques and scanning electron microscopy. Uptake of inorganic Hg from wat er was much more important in T. zonatus than in S. alpinus and the Hg conc entration in S. alpinus increased at a slower rate in all tissues during th e first 24 h of exposure. After 96 h, Hg concentration was 70 times higher in the kidney, 10 times higher in liver, intestine, skin, and brain, and 3 times higher in gills, muscle, and the rest of body of T. zonatus compared to S. alpinus. Gill damages in T. zonatus were more evident and occurred mu ch earlier than for S. alpinus. According to our data, the high differences observed in the inorganic mercury uptake, bioaccumulation, and gills damag es strongly suggest that T. zonatus is more sensitive to inorganic mercury pollution than S. alpinus. Further studies are urgently needed to determine whether the high sensitivity observed for T. zonatus to inorganic Hg is al so present in the majority of tropical species or whether this species pres ents an isolated case. (C) 2000 Academic Press.