The paper is concerned with the procedures of treatment of wastewaters from sugar-processing plants. A short survey is given of both the aerobic and anaerobic procedures with a special regard of the possibility of recirculating the treated wastewaters. Data are presented for treatment of wastewaters originated from sugar-processing plants by the active sludge procedure carried out on a laboratory scale. It was concluded that thus purified water, after final membrane treatment, could be recirculated to the production process.

One-year monitoring program was organized with the aim to assess the quality of sediment and water in these Vojvodina watercourses: the Begej, the Sava, the Botos, the Tisza, the Tamis, the Danube and the Danube-Tisza-Danube (DTD) Canal regarding metal content (Cr, Cd, Cu, Ni, Pb, Zn, Hg) in them. Water was the 1st/2nd class by MPL of national requirements, except occasionally for the copper concentration on some locations. The highest concentrations of zinc, cadmium, chromium, copper and mercury were detected in the Begej sediment. Maximum nickel concentration was in the Sava sediment, and for lead in the Danube sediment.

Management of aquatic ecosystems and planning of their protection needs good knowledge about their conditions. Mathematical modeling becomes one of the basic things in that processes. Last decades was attain important progress in quality at the beginning relative modest models of aquatic ecosystems. During the analysis of existing experiences to forced a conclusion that a quality model in one's own structures needs proportional representation of hydrodinamic and ecology background.

Faculty of Science, University of Kragujevac (Serbia, Serbia and Montenegro), has developed SeLar Information System (Serbian Lake and Reservoirs Information System) which provides all the information of Serbian lakes and water reservoirs. Information system is needed for transfer of knowledge and informations, cooperation among participant in management and support of sustainable using of water resources. The paper presents the basic system components and some applications examples.

The examined period is characterized by small floristic variety and well advanced eutrophication process. By the phytoplankton qualitative analysis it has been noted the domination of Bacillariophyta algal division. The values of density on phytoplankton population and their biomass show the domination of bluegreen algae, before each other, that of the species Gomphosphaeria lacustris Chod. As the consequence of the eutrophication, these algae develop intensively, up to the degree of water blossoming. The very high concentrations of the primary and secondary nutrients have also been noted. The trophic status of the reservoir on the basis of OECD classification can be defined as eutrophic.

Water quality studies of the Danube river in Belgrade region (Serbia and Montenegro) were performed at five locations, in June and September, 2003. Results of the qualitative, quantitative and saprobiological analyses of plankton and macrozoobenthic communities were used for the water quality assessment and the categorization of the watercourse examined. The bioindicator analysis points to the presence of mild organic pollution, water quality varying between the 2nd and 3rd class.

The paper presents the results of investigation of benthic algae of the river Rasina. During April, 2001, it was determined 110 algal taxa from the divisions Cyanophyta, Bacillariophyta and Chlorophyta, which indicate the high biodiversity of algae in this river. With 97 algal taxa, Bacillariophyta is dominant. The community of benthic algae is typical for this kind of aquatic ecosystem during the spring period. Great number of algal bioindicators of highly polluted water indicates the presence of high concentration of organic compounds in this aquatic ecosystem.

The puddle Slatina is the old meander of the river Tamis. It is periodically fill with moderate salt and high alkaline (pH 9) water. During our investigation it was determined 65 algal taxa from 5 divisions. Qualitative analysis points out on the domination of Cyanophyta, Euglenophyta and Chlorophyta, while quantitative analysis indicate the dominance of Cyanophyta. During spring 2003, total number of algae was 1.026 x 10**6 cel/l. High values of chlorophyll a (20 microgram/l) and total number of algae, as well as low transparency point out the progressive eutrophication.

This paper presents general characteristics of water source Mareza, which has been used for water supply of the town of Podgorica, as well as potential risks that can affect water quality of this source. Measures for the source protection in order to maintain existing high quality of the source water are presented.

Studies of the plankton copepods also included the area of continental shelf and the Southern Adriatic deep valley with pronounced ocean characteristics. The deep waters of Southern Adriatic are inhabited by numerous species of all depth zones, with a pronounced domination of ocean forms, similar to the Mediterranean. The quantity of copepods in the area of open surface waters shows a pronounced spring maximum of abundance. The abundance of overall copepod population decreases from the shore toward the open sea of Southern Adriatic valley, with an increase of species abundance in plankton. That area is governed by stenothermal and stenohaline conditions. The Copepoda community is characterized by stenothermic and stenohaline species. Ranges of many of these are not increased horizontally toward the northern parts of Adriatic, and the individuals carried north by water currents quickly die.