Available data on zooplakton research in Adriatic sea show that coastal and open waters of south Adriatic are the zone of most available and richest area in Adriatic sea. Shallow waters along the shore and the Boka Kotorska Bay are characterized by a monotony of faunistic content, while, by contrast, high values of biomass are caused by abundance of a small number of estuary-neritic species. Open waters of South Adriatic are characterized by holoplankton, while waters of Boka Kotorska Bay are characterized by meroplankton. Zooplankton of open sea shows a high diversity of fauna but a small biomass in part of open water above the geatest depths, and significantly high values of biomass in epipelagic waters above the continental shelf.

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.

During 2001, water from river Cerava and from the littoral where the river flow into lake Ohrid, were examined. Bacteriological analysis included ecological and sanitary aspekt of water state. Heterotrophic, proteolytic, amylolytic and phosphomineralizing bacteria, most probable number of total coliforms (MPN) and presence of Escherichia coli and Clostridium perfringens were determined. The results of investigations shows organic and faecal pollution and permanent negative anthropogenic effects.

This work show and compare results of chlorophyll 'a' and phaeophytin 'a' concentrations during three years systematic examination. The samples were collected from the fourth sector of Palic lake, ones a month, during 2000, 2001, and 2002 using method by Szilagyi. Comparing values, a great seasonic changes of chlorophyll 'a' and phaeophytin 'a' concentrations is noticed.

The work is concerned with the study of groundwater quality in respect of hydrocarbons content, carried out on several sites on the territory of the Oil Refinery Novi Sad (Serbia, Serbia&Montenegro). In the course of four year that elapsed since the time spillage of crude and oil derivatives and deposition of burning products on the Refinery soil (April-June 1999) the processes of passive in situ bioremediation have been taking place on the contaminated area. By comparing the results for three contamination zones in a circle of 270 m from the site at which the spillage occurred, a certain increase in content of mineral oil was observed in deeper water-bearing layers at a distance of 200 and 270 m from the spillage site. A content of BTEX components the "movement" of the pollution was observed from the close zone 1 via the farther zone 2 to the farthest zone 3, which indicates that the intensity of bioremediation and all physico-chemical processes in general, taking place on the pollution site, is not sufficient to prevent pollution spreading. The assumption that the zone in question in probably a limiting zone is based on the results of the fourth sampling campaign, in which BTEX components were not detected on any of the locations of the zones 2 and 3.

This paper presents the most important results on water quality investigation of the Danube river in the Iron Gate reservoir. The investigations are conducted by the Institute Jaroslav Cerni by means of regular monitoring renewed after a long pause in 2001. The determined phenomena are considered in regard to water quality of the Danube river in the upstream zone.

Forest ecosystems are important component of environment and row basis for wood processing industry. Traditional attitude about primate of productive functions in relation to useful functions, is under question, due to next reasons: exhaustion of sources of wood mass; affirmation of protective and regulative functions in domains of water-supply and erosion control. This attitide os represented in basic plan documents in Serbia, as well as in European Union. Protection, care of existing, and restoration of degraded forests, are the possibilities for development of high-profitable activities such as: recreation and sport tourism, hunting tourism and healthy food production.

During the parasitological investigations on the gills of 3 cyprinid species from Lake Dojran (the Former Yugoslav Republic of Macedonia), are found 4 monogenean species: in Rutilus rutilus dojranensis are found Dactylogyrus similis and Dactylogyrus suecicus, in Scardinius erythrophthalmus dojranensis is found Dactylogyrus difformis, and in Alburnus alburnus macedonicus is found Ligophorus sp. Prevalence in Rutilus alburnus dojranensis is 40.46%, in Scardinius erythrophthalmus dojranensis is 55.56%, and in Alburnus alburnus macedonicus is the lowest and amounts 2.02%. All monogenean species represents the first record for parasitic fauna of fish species in the Former Yugoslav Republic of Macedonia. Finding of Ligophorus sp. in the fishes of the family Cyprinidae is new to science generally.

According to existing national Standard for drinking water quality NO3 sup(-) ion is limited to 50 mg/l. Removal of NO3 sup(-) concentration greater than this limit is necessary. One of the possible methods is biological denitrification with CH3OH. Principals of this method are described in this paper with recommendation for construction of pilot plan on the specific groundwater source.

In order to increased the amount of water in Sjenica water reservoir (because of higher production of electric energy by hydroelectrical power plant), stagnant waters of Pester field were irrigated to Vapa river and Sjenica lake. Former swamp areas and theirs life communities, represented specific biological filter in Pester high, a kind of natural lagoons, where big amounts of polluted water with nutrients were spent a processed (especially salts of P and N) were characteristic for exact area because of intensive cattle production. After the irrigation on Pester field, raw, polluted water with the large amount of nutrients by Vapa river get to the Sjenica water reservoir where they represented main cause of eutrophication and degradation of water quality in this aquatorium. Heterogenic and numerous algal association in canal of the Pester field is nearly leftover of previous specific algological flora which testifies the presence of species Chaetophora incrassata Hazen (new habitat in Serbia), the first class water indicator.