Biomonitoring potential evaluation of a teleost fish species (Rutilus kutum) from the Caspian Sea through elemental fingerprinting of the hard- and soft part structures

This research was carried out in the area of the southern Caspian basin of the Caspian Sea in the vicinity of the estuaries of the White River, Tajan and Gorganroud rivers). In order to evaluate the ability to use five hard tissues (otolith, scales, hardcore radius, eye lens and dorsal vertebrae) of Rutilus kutum, and to assess the biochemical capability by measuring the changes in the bioavailability of the elements, as well as studying the accumulation of elements In macular tissues and their potential risks due to their consumption, 60 whitefish samples from three stations were sampled by bridging tours in June 1395. In total, the accumulation of 13 main and minor elements in the specimens (five hard tissues and two muscle and liver tissues) was investigated by the pixel method. Generally, the pattern of elemental accumulation in the lens of the eye was quite different from that of other tissues. The order of the accumulation of the elements in the two soft tissues studied was approximately the same, but Sr was not detectable in the muscle tissue. Ca, Fe, S, Cl and K elements were detectable in all tissues studied, but the Br element was only measurable in otoliths. The least similarity is found between the tissues in the eye lens (elements P, S and Zn) and the liver (elements Cl, Fe and K). While in the case of the Sr and Ca elements, the ottolate revealed the maximum distance. On the other hand, in terms of the accumulation of K, soft and hard tissues can be categorized into two completely separate groups.No significant correlation was observed between the elements and the biometric characteristics (weight, total length, and standard length). Based on the results, it appears that all hard tissues, except the lens of the eye, may be potential alternatives for the bioassay of Ca, Cl, Fe, K and S in the southern basin of the Caspian Sea. Scales and radius of fins can be considered as potentially non-lethal alternatives for other hard structures. Among the elements that were measurable using the piccil method in the macular tissue (muscle), only four of the Zn, Cu, Fe, and Mn thresholds allowed in some international standards are defined, which means the mean values measured in this study In all cases, in comparison with the standards, it is much less. Therefore, it seems that the consumers of this fish are not in danger of being exposed to the threat of accumulation of the four elements in fish.

Iranian Fisheries Science Research Institute

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