In November 2001, October and November 2002, the concentrations of Hg, Cd, Pb, Cr, Cu, Zn and Ni were determined in four localities of the lower course of the Jihlava River (Czech Republic). The river water, sediments of the riverbed, zoobenthos and tissues of the fish (gill, gonad, skin, dorsal muscle) were analysed. The chub (Leuciscus cephalus) was used as the ichthyo-indicator. At the same time, the stability of the fish community was evaluated using electrofishing and applying basic ichthyological methods. The work links up with previous investigation of the upper course of the Jihlava River (three localities) carried out by the authors in the same way in 1999. The aim of present study was the completion of previous investigation in the whole longitudinal river profile by monitoring selected heavy metals. The highest Cr (14.290 -77.070 mg/kg), Zn (13.600 -92.930 mg/kg) and Ni concentrations (12.290 -36.680 mg/kg) were found in sediments and their highest loading by all of the monitored metals (without Ni) was detected in the last downstream locality (Pohořelice). Zoobenthos was most contaminated by Zn and Cu (7.480 -62.690 and 8.050 -21.810 mg/kg). In the body tissues of the chubs, the highest concentrations of Cd, Hg, Cu, Zn and Ni were determined in the gills, while Pb was also high in gills but also in gonads, the skin and in the muscle tissue. Concentrations of the analysed metals in the chub muscle were (in mg/kg): Hg 0.040 ± 0.014 -0.133 ± 0.063, Cd 0.003 ± 0.002 -0.010 ± 0.004, Pb 0.045 ± 0.038 -0.768 ± 0.038, Cr 0.046 ± 0.023 -0.106 ± 0.092, Cu 0.203 ± 0.123 -0.634 ± 0.194, Zn 4.25 ± 0.84 -6.69 ± 2.95 and Ni 0.062 ± 0.018 -0.103 ± 0.030. Significant differences in the chub muscle were found concerning Hg, Pb, Cu (P < 0.01) and Cd (P < 0.05). Taking into consideration the actually valid FAO/WHO limits for human consumption of chub muscle from the investigated river section, only Hg (PTWI 2.3 kg in locality 7) and Pb (PTWI 2.0 kg in locality 4) could constitute some risk for human health. The index of diversity of the fish community was 0.825 -2.110, equitability index 0.380 -0.793, abundance 312.6 -2,106.5 fish/ha and biomass 46.7 -451.5 kg/ha. The water quality was characterized as betamesosaprobic (saprobity index 1.77 -2.18). The results of the study reveal detailed ecological data concerning heavy metals contamination of the whole Jihlava River ecosystem (water, sediment, zoobenthos, fish). The outcome of this study extends our knowledge about metals accumulation in different fish tissues (gill, gonad, skin and muscle).

Contents of total mercury and mercury species (methylmercury &ndash; MeHg, inorganic mercury &ndash; Hg²⁺) were determined in four Moravian rivers &ndash; Jihlava, Becva, Loucka and Dyje (Czech Republic). Five tissues (muscle, gills, liver, kidney and skin) of chub (Leuciscus cephalus), zoobenthos, sediments and water samples were analyzed. Time stability of samples was also tested. The highest levels of total mercury were determined in muscle tissues of all tested fish. Relative contents of MeHg in muscle tissues of fish ranged from 83.6% to 92.0% of the total mercury contents. The relative contents of MeHg in sediments and in zoobenthos samples correlate very closely (correlation coefficient &ndash;0.83). A considerably lower content of MeHg (1.3&ndash;11.4%) was found in river sediments compared with lakes. A comparison of observed sampling sites (Vladislav, Hrubsice) proved the adverse effect of industrial contamination on the water ecosystem ofJihlavaRiver and incomplete removal of mercury species in a sewage station

Vítek T., P. Spurn˘, J. Mare‰, A. Ziková: Heavy Metal Contamination of the Louãka River Water Ecosystem. Acta Vet Brno 2007, 76:149-154. Heavy metal contamination of the Louãka River water ecosystem was assessed in July 2005. We analyzed concentrations of T-Hg (total mercury), Cd, Pb, Cr, Cu, Zn, and Ni in water, sediments, zoobenthos, and in the brown trout (Salmo trutta m. fario) muscle and liver tissues (a total of 28 individuals) at four sampling sites. The highest Pb and Ni concentrations (4.634 -12.050 and 0.689 -24.980 mg·kg -1 ) were found in sediments. The zoobenthos was most contaminated by Zn and Cu (0.556 -1.505 and 2.925 -74.300 mg·kg -1 ). The heavy metal contamination of river water was highest in Ni and Cr (0.1 -6.8 and 0.5 -10.0 mg·l -1 ). Concentrations of heavy metals in the brown trout muscle were following (in mg·kg -1 ): Pb 0.108 ± 0.073 -1.010 ± 0.506, Cd 0.003 ± 0.002 -0.026 ± 0.022, Zn 3.956 ± 0.371 -5.801 ± 1.718, Ni 0.058 ± 0.018 -0.102 ± 0.046, Cr 0.028 ± 0.005 -0.073 ± 0.039, Cu 0.329 ± 0.079 -0.437 ± 0.064 and Hg 0.065 ± 0.008 -0.106 ± 0.047. Statistical differences (P < 0.05) in the brown trout muscle were in Pb and Zn. Cd, Cu and Zn were markedly accumulated in the brown trout liver (concentrations 0.107 ± 0.066 -0.223 ± 0.078, 59.973 ± 38.951 -145.800 ± 48.286 and 30.671 ± 3.574 -34.274 ± 7.226 mg·kg -1 ). Humans of 60 kg body mass may consume 1.5 kg of brown trout muscle from the Louãka River weekly without any risk. Adverse influence of the Uniglas distillery on the Louãka River environment contamination by heavy metals was not confirmed.

Fish communities of the Bečva River were studied in summer and autumn 2000 and 2001. Electric fishing gear (Honda EX 1000, DC 230 V, 0.75-0.9 kW) was used for sampling. Four sampling sites (Grymov 19.6 r. km, Rybáře 35.8 r. km, Hustopeče 50.7 and Choryně 54.7 r. km) were selected. Total of 23 fish species representing 5 families were determined. The family Cyprinidae with 15 species was dominant while Salmonidae, Balitoridae, Percidae and Gadidae were the other recorded families. Species diversity ranged from 9 at Hustopeče to 20 at Grymov localities. The lowest biomass and abundance were observed at Hustopeče locality (28.93 kg/ha and 336 fishes/ha) and the highest at Choryně locality (612.90 kg/ha and 7 367 fishes/ha). Barbus barbus, Chondrostoma nasus and Leuciscus cephalus contributed 87.73-97.55% and 60.5%-87% to total biomass and abundance in different samplings, respectively. The Chondrostoma nasus population was dominated by fish of total length over 300 mm. We believe that river fragmentation, trapping and blockade of fish are the main reasons for this irregular distribution. Index of diversity ranged from 0.811 to 2.05 and equitability index from 0.449 to 0.821. Physical and chemical parameters were also measured, pH value ranged from 7.8 to 9.8, DO (7.62-12.15 mg/l), conductivity (450-639 µS/cm), N-NH 4 (0.65-2.39 mg/l), P-PO 4 (0.12-0.68 mg/l) and alkalinity (2.55 to 3.40 mg/l).

Abstract:© Versita Sp. z o.o. Received 22 February 2011; Accepted 12 August 2011 Keywords: Mercury determination • Fish muscle • Scale • FinThe determination of mercury in fish typically involves analysis of muscles. For predicting the concentration of mercury in fish muscle on the basis of the analysis of fish scales or fins, the relationship between total mercury concentrations in fish muscles and in fish scales and fins was studied. Mercury content in fish muscles, scales and fins was determined by atomic absorption spectrometry with thermal decomposition of the sample in a flow of oxygen. A number of scale treatments were applied in order to remove impurities and to enhance the prediction quality. For scale treatment, 40 min of washing with DI water in an ultrasonic bath is recommended. A coefficient of determination r 2 = 0.93 for the relationship between Hg concentrations in muscles and scales was achieved for 40 fish among the different fish species tested (European bream, perch, roach) from the Hamry Reservoir, Czech Republic. With respect to fin sampling, the coefficient of determination r 2 for these fish was 0.86. The analysis of fish scales and caudal fins is a useful screening tool for assessing the relative mercury contamination of monitored fish. The method of sampling scales is not suitable for fish species with small scales such as brown trout.