F Moezzi - Department of fisheries, faculty of natural resources, university of Tehran, Karaj- Iran
A Javanshir - Department of fisheries, faculty of natural resources, university of Tehran, Karaj- Iran
S Eagderi - Department of fisheries, faculty of natural resources, university of Tehran, Karaj- Iran
H Poorbagher - Department of fisheries, faculty of natural resources, university of Tehran, Karaj- Iran

Heavy metals as important pollutants in aquatic ecosystems can cause adverse biological effects on live organisms of these environments. This research was conducted to study the bioaccumulation of zinc (Zn) in internal organs (mantle, gill, hepatopancreas and foot) of the freshwater bivalve, Anodonta cygnea during 27 days in vitro exposure period. Results showed that this species has a high potency of metal accumulation. There was no significant difference between basal Zn levels in studied organs. Maximum accumulation rate were recorded in gill and hepatopancreas and their Zn content was significantly (?=0.05; P < 0.02) higher than mantle and foot. The minimum Zn accumulation occurred in mantle. Zn levels in gill, hepatopancreas and foot were increased during exposure period, but a decreasing trend was observed in Zn level of mantle between days 18 and 27. The results of this study indicated that accumulation potential of different organs and their sensitivity and impressibility are different and gill and hepatopancreas are appropriate organs to study heavy metal bioaccumulation and their pollution in freshwaters.

Zinc, Anodonta cygnea, Bioaccumulation, Internal organs