The fact is that in the world today water and land represents limited life resources which are more and more degrade and disturbed, mostly by anthropogenic influence. Especially water (seas, rivers, lakes) is exposed to various types of pollution. The fact is that in the world today water and land represented limited life resources which are more. That why in present time we conduct numerous scientific researches to examine, advance and protect our environment, especially water as a limited and delicate natural resource. In this work results from April to September 2011 are presented, which comprised analyses of samples from 8 stations in Boka Kotorska Bay. The main aim was to estimate trophic level, of determining the concentration of the physico-chemical parameters, chlorophyll a and TRIX index in Boka Kotorska Bay.

Complex hydrodynamics and thermal regimes of temperate lakes have a major impact on temporal and spatial distributions of water quality indices. Transport processes in lakes are driven primarily by external forces such as wind and solar radiation but also depend on the inflow and outflow regimes. This paper presents a simplified ID model developed to calculate seasonal variations in vertical distributions of temperature and dissolved oxygen in Lake Zavoj in southern Serbia. Model results that were based on monthly averaged meteorological data are in good agreement with measured vertical profiles of temperature and dissolved oxygen. The simplified model is an efficient tool for long-term prediction of water quality indices in deep, medium and long residence time lakes.

In this work results from April to September 2009 are presented, which comprosed analyses of samples from 15 stations along Montenegrin coast. The main aim was to estimated level of eutrophication and phytoplankton community characteristic for eutrophic area. Maximum mean value of microplankton of 8.4 x 10**5 cells/l was noted in the inner part of Bokakotorska Bay. This area has maximal values throughout all period of investigation. It is result of waters dynamics and influence from the coast. In the open sea values were lower, about 10**4 cells/l. These results show that Montenegrin coast is an eutrophic region. Some phytoplankton organisms characteristic for eutrophic region were found also. The most abundant species was Thalassionema nitzschioides with maximum mean value of 8.4 x 10**5 cells/l.

The weekly measurement of physico-chemical and biological parameters was done during the spring of 2008 in order to assess the level of eutrophication in the Kotor Bay. Chlorophyll a was used as trophic level indicator and its values varied from minimal 1.00 mg/cubic meter in June on the depth of 10 m to maximal 3.71 mg/cubic meter on the sea surface in May. According to Nixon criteria during investigation period it can be concluded that the area in question is oligotrophic. On the other hand, according to UNEP criteria which are somewhat stricter when the concentration of chlorophyll a is in question, Kotor Bay was mesoeutrophic area.

In the paper we presented the effort to collect the recent data clarifying eutrophication as one of the commonest problems of freshwater. The paper includes experience of researchers related to causes of onset and effects of eutrophicational processes on trophic level increase in reservoirs.

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.

On the base of monitoring of water quality for aquaculture, performed since 2010, it is noticed that two positions are showing increased level of trophicity and bacteriological contamination. Changes in sanitary quality of farms are especially intensive during the summer months, so the results of basic physical, chamical and biological parameters, measured during periods June-September 2010 and 2011 are presented and compared.

The aim of this work is to present the trophic state of water at the pelagic zone of lake Prespa, reviewing the result of defined parameters of physico-chemical and algological aspect. Investigations are done according to standard limnological methods and the samples for analysis were collected from one vertical profile (0, 5, 10 and 15 m) monthly during 2008 year. Water categorization, on the basis of gathered data from analyses of the sampling localities was done according to the OECD-regulations, positive law regulations of the Republic of Macedonia and Nürnberg classification system. Data from this investigating period point out that this area of the lake Prespa is by great influence of the anthropogenic factor and intensive eutrophication.

In this paper some results of investigations of physical, chemical and biological parameters were presented from the parts of Montenegrin coastal sea exposed to the impact of the open waters of the Southern Adriatic sea. As Herceg Novi area is simultaneously the part of the Boka Kotorska Bay (which goes deeply to mainland), eutrophication is more visiable there. Biological parameters were the most visiable indicators of eutrophication during these investigations.