The Mercury Content in Fish from the Jordán Resesvoir in Tábor.

The aim of those study was to find out an up-to date content of mercury in the tissues of fish in the dam reservoir Jordan in Tabor. To compare particular fish according to their species, age and dietary strategy and their capability to accumulate mercury. The distribution and the mutual rates of total content of mercury in particular tissues of carnivorous and non-carnivorous species of fish were determined (muscle, liver, kidneys). Dedicated atomic absorption spectrophotometer AMA 254 was used to determine the total content of mercury. The results show that exceeding the former hygienic limit 0.1 mg.kg-1 w. w. in the muscle of non-carnivorous fish with almost all samples. It was the low-age carnivorous species of fish was probably the cause that the hygienic limit (0,5 mg.kg-1 w. w.) was exceeded only rarely (in the muscle a five-year-old asp, Aspius aspius, 0,888 {$\pm$} 0,041 mg.kg-1 w. w.). The pond Kosin located above the dam reservoir Jordan was exploitation as a comparative locality. The average content of mercury in the muscle of selected indicator species of fish in the reservoir Jordan - bream large (Abramis brama) at the age of 5 years - it was 0,241 {$\pm$} 0,080 mg.kg-1 w. w., whereas from comparative locality, from the pond Kosin, for the same species and age of fish it was only 0,045 {$\pm$} 0,008 mg.kg-1 w.w., i.e. more than five times more of the content in comparison with an unweighted locality. The realized results also show that the burden of the fish with mercury for a common consumer does not exceed neither the {\clqq}hazard index`` (HI) nor the toxicological limit ( the maximum recommended ration a week from the food is 1,6 {$\mu$}g MeHg per 1 kg of body weight according) to the WHO. However, with more intensive consumption of mainly carnivorous fish from the reservoir Jordan, e.g. of the sport fishermen´s family members, it could cause risk from this consumption ( i.e. HI > 1). Further work should be aimed at monitoring of the content of mercury in the tissues of mainly predators of higher age category