Comparative analysis of results obtained in hydrobiological research conducted to date indicates that relatively few water reservoirs in Serbia have been subjected to complex hydrobiological investigations. Apart from the fact that hydrobiological investigations are now performed on only a small number of water reservoirs in Serbia, they are moreover inadequately coordinated, which is especially evident in differences of procedural approaches employed. With adoption of the principles of modern limnology and wider use of new criteria for water classification (m WQI for instance), the current state of hydrobiological research constitutes a basic for the development of comprehensive program of planned continuous studies of water reservoirs in Serbia resulting in their rational and successful management.

Heavy metals contamination of the muscular tussue of nase (Chondrostoma nasus), bream (Alburnus brama) and bleak (Alburnus alburnus) fish species from the Medjuvrsje water reservoir (the Zapadna Mora river), was examined. With the expection of the nase muscular tissue where cadmium (Cd) and mercury (Hg) concentrations above and slightly below MPC, respectively, were detected, the rest of the samples were safe. With the aim of conducting more thorough monitoring of these pollutants, a greater number of elements and a larger number of organisms should be included in the analyses.

In this paper is given the comparative review of investigation of the macrophytic vegetation and ichthyofauna in 4 localities (Grasnica, Gradiste, Veli Dab, and Cerava) from the littoral region of the Lake Ohrid. In the investigated localities are evidenced macrophytic species and fish species as bioindicators for saprobility. Based on the obtained results, it can be concluded that qualitative composition of macrophitic vegetation and ichthyofauna are different and depend from locatities where investigated made.