Mehdi Bibak

The Caspian Sea is the largest inland body of water in the world and so has both common characteristics of seas and lakes with over 153 fish species which inhabit the sea and its basin. However, little is known about the trace element (TE) contaminations (TECs) in its tissues. In the present study, 122 specimens of three fish species including Rutilus caspius (Roach, n=71), Leuciscus aspius (Asp, n=20), and Tinca tinca (Tench, n=31) were collected from three different fisheries regions (i.e. Astara, Anzali and Kiashahr) of the southern part of the Caspian Sea from September 2017 to June 2018. Inductively coupled plasma optical emission spectrometry (ICP-OES) was employed to measure TE levels in different fish tissues. An attempt was made to assess possible influences of habitat on element accumulation in the liver and kidney of three fish species in the southwest of the Caspian Sea basin. Some elements including Ca, K, Mg, P, S, Sc, and Sr showed different concentrations in the liver and kidney. Also their levels were significantly different between freshwater resident (Tench) and marine (Roach) species (p < 0.05). The differences among TECs in the liver and kidney of Roach, Asp and Tench were reduced to three components using principal component analysis (PCA). Results indicated that 83.60% of the total variability is related to TEs such as Cu, Fe, Sr, Ca, S, Na, Mg, K, and Al. The impact of habitat variability on the element accumulation was confirmed through linear chart obtained for liver and kidney (as body filtering organs) of Roach and Asp as marine residents as well as Tench as a freshwater resident. This could illustrate the borderline created by these habitats.