Research of the seasonal dynamics of the zooplankton abundance was carried out during the two-year period from January 2005 to December 2006. The sampling took place in monthly intervals from five different sites from the surface to the bottom of the lake. Taking into concidertion the temperature and oxygen regime the division on the epilimnion and hipolimnion was found out. Significant numerous in the total abundance of the zooplankton accomplish taxa Daphnia sp., Bosmina sp. and Cyclops sp. Zooplankton is more abundant in the epilimnium, in the layer with more favourable temperature and oxygen regime comparing with hipolimnium. Presence of the zooplankton has been recorded in the lack of the oxygen in hipolimnium during summer months. After the elimination following the heavy rains, the hasty increase of the zooplankton numerous was recorded. Abundance of the zooplankton was higher was in shallow parts of the lake in the area of the mouth comparing the sites close the dam. This research has shown that the zooplankton was present in all parts of the lake during entire year, especially in the epilimnion that characterizes with the favourable temperature and oxygen conditions.

The paper presents the results of aquatic macroinvertebrates community analyses of the Moravica river with the aim to evaluate saprobiological status. Sampling were carried out tree localities during 2003 and 2004.

The objective of the paper is establishing of eco-chemical characterization of the river system by investigating and distribution heavy metal content in the river sediments using sequential extraction and total digestion. Heavy metals toxicity and bioavailability in the Danube river sediment are defined according to their distribution between different phases. Sediments samples were taken from 9 sites and analysed for cadmium (Cd), iron (Fe), manganese (Mn), lead (Pb), copper (Cu), zinc (Zn) and chromium (Cr), and the results about cadmium and iron presented in this paper.

The Water Book maintenance is obligated. The electronic form of Water Book and following documents provides an insight into data from issued water acts, in a simple, systematic and arranged way, which enables easy and fast search, according to assigned key, of data extraction and report printing. Program package is provided by Republic Directorate for Water. The implementation of Water Book program is realised in the Ministry of Agriculture, Forestry and Water Management of the Republic of Serbia - Republic Directorate for Water. Public water enterprises and communities that have technical capacities for program installation.

Due to very high concentration of organic matter there is a great need for alternative solutions for drinking water disinfection in the world. Chlorine dioxide has been successfully used for almost 50 years for disinfection and later for taste removal, odor control, color reduction and oxidation of inorganic compounds such as iron and manganese. An advantage of using chlorine dioxide instead of chlorine is that it does not directly react with organic matter and form halogenated byproducts when it is used for disinfection. THMs, such as CHBr3, ChCl3 etc, are considered as most dangerous for people health. In this article we are to represent the results got from raw water disinfection treatment with chlorine dioxide.

Samples for phytoplankton investigations were collected in annual period (September 2003 - August 2004) in the Kotor and Risan Bay. Mean-values percentage contribution of the group diatoms (Bacillariophyceae) through the annnual period were from 79.70% to 86.50%. Species Skeletonema costatum, Pseudo-mitzschia delicatissima, Leptocylindrus minimus and Chaetoceros affinis, were the main edificators of diatom population. Densities of these species were from 10**5 to 10**6 cells/cubic dm. These values are characteristic of eutrophic and extreme eutrophic area. It is needed one permanent monitoring to protect this part of Boka Kotorska Bay negative consequences.

In Boka Kotorska Bay there are two recorded species of Copepoda from family Temoridae: Temora stylifera and Temora longicomis. This paper presents the data on horizontal distribution and abundance of these species during 2007. Temora stylifera has a wide horizontal distribution in coastal and open waters of Adriatic sea, while Temora longicomis is a typical representative of estuary-neritic waters of northern Adriatic, Kvarner area and the Italian coats at the west. Their abundance was particularly high in spring and summer.

Lake ecosystems determined by trophic conditions, accurately defined Ecological status of protected area. Trophic condition of water of Lake Skadar and two rivers, the inflow Moraca and the outflow Bojana was described via plankton data considering abundance of phytoplankton, seasonal dynamics of organotrophs, cyanobacteria, total coliforms, plankton biodegrading potential and nitrogen fixing bacterioplankton. The trophic potential for phytoplankton growth has been detected in late autumn throughout September-November 2004, contrary to early summer June-July 2005, and adverse growth of bacterioplankton in May, June and September 2005, respectively. The results of quantitative analysis of coliforms showed good relation of Lake Skadar and Ada Bojana, contrary to similarities between Moraca River and Ada Bojana estimates in accordance with the Pantle-Buck index. Nevertheless, investigation pointed out Lake Skadar beta-mesosaprobic level and moderate self-purification rate. In evaluating trophic conditions the good ecological potential of protected area has been proposed.