In the year 2010 ichthyological research on some Vrbas River tributeries located on wider area of Banjaluka city (Bosnia and Herzegovina) was carried out and the occurrence of 14 fish species was recorded. On the basis of the occurrence and abundance of fish species indicators as limnosaprobic parameter, water quality of the analyzed watercourses variated from oligosaprobic to beta mesosaprobic (I and II class of bonity) with saprobic index from 1.27 for Švrakava River to 1.81 for Vrbanja River. The obtained results indicate that water quality of this Vrbas River watershed was on satisfactory level for multiple purposes (in order to sustain ichthyofauna diversity and production and as potential protected areas and spawning zone for some endangered domestic fish species).

In this work, the results of preliminary study of stomach content in brown trout (Salmo trutta L. 1758) of the Gradac in autumn are presented. The fishes were collected by the end of September of 2011 at three sampling sites along the course. A total of 12 fish specimens were examined. By examination of trout stomach content have been found members from macrozoobentho-groups – Trichoptera, Ephemeroptera, Diptera (fam. Ceratopogonidae), Oligochaeta, Coleoptera. At the same time, investigations of bottom fauna composition and structure have been done also. Our study showed that the diet of brown trout is dependent of bottom fauna availability and abundance.

This paper presents the results of chemical analyzes of water and sediment of the River Tisza, in the section from the Hungarian border to the mouth of the Danube. According to local legislation, water quality in the Tisza is acceptable, i.e. does not exceed the maximum allowable values for Class II watercourses for most parameters at almost all sampling locations. by using the Dutch methodology, it was concluded that the sediments of the Tisza at all profiles is categorized as polluted due to the high mercury and/or nickel contents, except for the profile downstream of Senta, which is partially contaminated. All the sediments are partially polluted in terms of copper content, and the sediment in the profile downstream of the dams is also partially polluted with zinc. The results of this analysis can be used to obtain a preliminary picture of the vulnerability of the Tisza River over its course in Serbia to the large number of industrial pollutants that are present in wastewaters discharged into the river or in the lateral canals that empty into the Tisza.

The paper presents a comparison of measurements of selected organic pollutants in various water matrices, in order to assess the impact of the matrix on the accuracy of pollutant analysis. Selected compounds were from class of phenols (p-nitrophenol, 3,5-dichlorophenol)and organochlorine pesticides (isomers of hexachlorocyclohexane (HCH), heptachlor, aldrine, heptahloroepoxide, 4,4'-DDE, dieldrine, endrine, 4,4'-DDD, endrin aldehyde, 4,4'-DDT, endosulfan sulfate). Apart from distilled water and synthetic aqueous matrix (salt addition in distilled water according to DIN EN 12902 standard), natural matrix was also used in the analysis – surface water (River Danube in Novi Sad – DOC (dissolved organic carbon) 2-6 mg/l, suspended matter content 30 mg/l).

In this paper aquatic macroinvertebrate community of the Peštan River was presented, including the characterisation of the species with regard to saprobic conditions and preference to the mineral substrate type. Sampling was carried out during 2011 at man stream and tributaries. A total of 52 taxa have been identified. According to the ecological classification of the taxa with regard to saprobic conditions for the main stream, the most species belong to the alpha-mesosaprobic group while majority of the species from the tributaries were characterised as beta-mesosaprobic species. The most of registered species preffered substrate type characteristic for lowland river. Results of saprobiological analysis indicate poorer status of the main stream in regard to tributaries.

The aim of this study was to assess the water quality of the Gradac, near the town of Valjevo, on an analysis of DNA damage in different tissues of trout (Salmo trutta L. 1758) and barbel (Barbus meridionalis R. 1827). For the detection of genotoxic potential of alkaline comet assay were used three types of tissue, blood liver and gills. Among the parameters available the Olive tail moment was chosen as the most reliable to estimate the damage to DNA molecules. In all tested tissues was detected damage in DNA molecule, where the gills showed the highest sensitivity.

The aim of this work is to present preliminary results of the Sava River investigation at five sites within the reach from Martinska Ves (Croatia) to Šabac (Serbia). A total of 70 macroinvertebrate taxa from 13 groups were recorded, with domination of molluscs and oligochaetes. Among them 7 alien species were registered. Invasive clam Corbicula fluminea was recorded at all five sites, while invasive amphipod Dikerogammarus haemobaphes was not recorded only at locality Šabac. It is expected that the taxa list of aquatic macroinvertebrates within investigated reach will contain more species, after the identification of the rest of biological material and more detail identification of certain taxonomic groups.

In the case that water quality data or even discharge data are missing, pollution loads were calculated as application of appropriate simulation models of pollution transport. Models can be in different levels complexity. Accuracy of the results depends on the accuracy of measurement data. In this study water quality of River Neretva (prediction of BOD pollution loads) is modeled in section from Mostar to Žitomislić using numerical model MIKE 11. Model is calibrated on the basis of available experimental data. Data of another time series are used for verification of last mentioned. The comparative analysis between measured and simulated data showed that MIKE-11 is able to predict sufficiently accurate BOD and DO loads at the catchment outlet.