CHANGES IN MORPHOLOGICAL INDEXES OF YOUNG ATLANTIC SALMON (SALMO SALAR L.) EXPOSED TO HEAVY METAL (ZN, CU, NI, CR, PB, CD) MIXTURE: AN EXPERIMENTAL STUDY / ATLANTINIŲ LAŠIŠŲ (SALMO SALAR L.) JAUNIKLIŲ MORFOLOGINIŲ RODIKLIŲ POKYČIAI VEIKIANT SUNKIŲJŲ METALŲ (ZN, CU, NI, CR, PB, CD) MIŠINIU: EKSPERIMENTINIS TYRIMAS

Morphological indexes are indicative of toxicant effects in fish. Unfortunately, morphological parameters [gill-, liver-, kidney-, viscero-, etc., somatic indexes and the integrated condition factor (CF)], are usually determined in field studies to assess the general fish condition under effect of multicomponent pollution and did not reflect the effects of specific polluting substances (e.g. heavy metals). The purpose of this study was to experimentally evaluate the effect of priority heavy metal model mixture formed based on Maximum-Allowable-Concentration accepted for Lithuanian receiving water bodies (Zn – 0.1, Cu – 0.01, Ni – 0.01, Cr – 0.01, Pb – 0.005 and Cd – 0.005 mg/L, respectively) on condition parameters of one-year-old Atlantic salmon after seven-, fourteen- and twenty eight- day exposure. Significant changes in liver-, kidney- and viscero-somatic indexes were determined, while CF and branchio-somatic-index were found to be not indicative for such kind of the exposure. Correlation analysis between the parameters studied revealed a number of meaningful patterns. The obtained data were compared with the results of the field study in salmonid rivers