ESTIMATION OF SOME HEAVY METALS BIOACCUMULATION IN TISSUES OF THE INTESTINAL CESTODA POSTGANGESIA ARMATA AND ITS DEFINITIVE HOST; THE EUROPEAN CATFISH SILURUS GLANIS (L.) FROM TIGRIS RIVER PASSING THROUGH NORTHERN N. GOVERNORATE, IRAQ

Objective: The purpose of the study is to pursue some heavy metals in the aqueous environment of Tigris river that passes through Mosul city prior to the bioaccumulation of such metals in catfish Silurus glanis and its intestinal tapeworm Postgangesia armata. Methods: Silurus glanis, a freshwater fish were hunted from Tigris river passing through Al-Rashidiya region/Nineveh Governorate, North Iraq, during November 2017 and May 2018. Bioaccumulation of Fe, Cr, and Mn were estimated in different body tissues of infected and uninfected catfish, and in catfish intestinal tapeworm P. armata. Atomic absorption Spectrophotometer was used to estimate heavy metal concentration as µg of a particular metal/gm of fresh weight. Results: Concentration of the metals in catfish tissues were in the order of Mn > Fe > Cr. Whereas, concentration of the metals of the tapeworm P. armata were in the order: Fe > Mn > Cr. Moreover, mean concentrations of the three heavy metals (Cr; Fe and Mn) were lesser in body tissues of infected catfish than in the uninfected fish. This lessening of metals accumulation in the infected fish may be related to the presence of the intestinal tapeworm.  It also appeared that the three metals are mostly accumulated in liver of the catfish, then in gills, and muscles at lesser extent. Conclusions: Present work is drawn out that measuring concentration of heavy metals in parasitic and host tissues that inhabit a certain aqueous environment could be adopted as bioindicators for assessing heavy metals pollution.