The paper presents the results of preliminary study of the intestinal content in bream (Abramis brama L. 1758) of the Danube River through the Belgrade Region. The fishes were collected in May and October during the period 2007-2009 at two sampling sites along the course. A total of 42 fish specimens of different age (2+ to 6+) were examined. By examination of compositing of intestine of bream have been found members from macrozoobentho-groups – Oligochaeta, Gastropoda (Lithoglyphus naticoides), Bivalvia, Amphipoda (Gamaridae). Our investigation showed that the diet of bream is dependent of bottom fauna composition and structure.

Physico-chemical and microbiological analysis of Brvenica River water was conducted in period 2006-2010 and showed seasonal variations of water quality. The results of correspondence analysis indicated that the year 2006 regarding the physical and chemical characteristics of water, was different from the rest of the examined period. This year was characterized by the absence of ammonia, low contents of nitrite, iron and chlorine, and increased concentrations of KMnO4 consumption. In 2007 and 2008 presence of manganese in water, low concentration of KMnO4 consumption was detected as well increased turbidity and electrical conductivity. And the third distinguish period are years 2009 and 2010 when water was characterized by low concentration of NO3, and the presence of ammonia, NO2, and iron in the water, while turbidity was low and conductivity was average. In Brvenica River water Escherichia coli, Citrobacter sp., Enterococcus sp., Klebsiella sp. are detected. In year 2006 number of aerobic bacteria and total coliforms were rather low, while their number in 2008 is relatively high. Over the whole period, only in 2008 fecal streptococci were not detected. Other years are characterized by growth of aerobic bacteria and total coliforms and the occasional presence of fecal streptococci. Throughout the whole examination period fecal coliform bacteria were present in the water.

Creation of scientific basis for rational use of water resources is impossible without studying viability of the microorganisms, their influence on the formation of chemical properties of natural waters and an explanation of the principles of biochemical processes such as transformation of elements in the aquatic environment. The survey of microbial (bacterial) characteristics of watercourses in the Republic of Srpska was conducted on a total of 64 streams within Operational, International and National surveillance monitoring. Sampling and analysis of samples was performed during the period from May to October. The study included ecological and sanitary aspects of river quality.

Research macroinvertebrates in the lower reaches of the River Veternica was conducted during 2008 in spring and summer season on nine sites, in period of reduced outflow of water from the Lake Barje, when the water level is often reduced to the biological minimum. The presence of 91 taxa from 13 groups of macrozoobenthos was detected. Groups of Diptera, Ephemeroptera and Trichoptera were presented with 18, while Megaloptera, Plesoptera and Nematomorpha with one taxon each. The spring has been allocated 69 and 70 taxa in summer. The average was separated 17 taxa. Average number of macrozoobenthos was 1440 ind/square m per site. The few types of macroinvertebrates were very abundant at the site before the river confluence into the South Morava River. Insects made up 66.4% of the total number of individuals, especially the numerous groups of Diptera with 45.7%, while the share of the group Aquatic amounted 31%. The largest shares of the total abundance of taxa were as follows: Chironomus thumma with 28.16%, Limnedrilus hoffmeisteri with 11.2% and Tubifex tubifex with 6.89% and Caenis macrura from 5.2%. The structural parameters indicate that diversity of macrozoobenthos reduces in downstream direction, reflecting degradation of ecosystems.

The research of benthic fauna was done in part of the River Temstica, the right tributary of Nisava. Sampling was conducted on four sites, between 10 and 18 July 2010. Quantitative and qualitative analysis revealed the presence of eight groups of macroinvertebrates. The most frequent groups were Diptera, Ephemeroptera, Plecoptera, Trichoptera. Lower presence was shown by the groups of Coleoptera, Chironomidae, Turbellaria, Hydracarina. The greatest species diversity was characterized by order Trichoptera, while the largest number of individuals was characterized by order Diptera. There has been stated a 10 new taxa for this aquifer, with a new taxonomic group – Hydracarina. It is necessary to conduct further research of this river, with a need to analyze more samples from several locations (to conduct a research of the entire river, including the river mouth), and through the annual seasonal dynamics.

The aim of this work was to determine the bacteriological status of water catchment, basin, which is used for water supply of the town of Krusevac, as well as the distribution of present bacteria morphotypes. The total count of bacteria ranged from 1.35x10**5/ml to 2.09x10**7/ml. The number of aerobic heterotrophs ranged from 415 CFU/ml to 64,500 CFU/ml. The differentiation of bacteria in three morphotypes (rods, cocci and curved) was made. Representation of rods ranged from 40.05% to 78.71%, cocci from 4.39% to 60.88% and curved from 1.54% to 17.20%. Seasonal and vertical distribution of morphotypes showed increased presence of rods and curved forms in terms of increased bacteriological load of water, while the presence of cocci increased in conditions of cleaner water.

Results of phytoplankton investigations that were performed in May, July, August and October 2010 are presented in this paper. The investigated areas are in Boka Kotorska Bay on four locations: Kotor Bay-IBM, Tivat Bay, Hercegnovi Bay-two positions and one position on the open sea – Mamula. In this area the influence of the open sea and the land are expressed to the phytoplankton community. As a consequence of that quantities of phytoplankton are lower in the outer part and higher in the inner part. Diatoms are the most dominant species, which is very frequent in the eutrophic area.

The concentration of trace metals (Pb, Cd, As and Hg) were measured in sea water and sediments in the coastline of the Montenegro. The obtained results of trace metals in sea water were compared with those found in the sediment. Sampling was performed in the fall of 2005 and spring 2006 at five locations in the Montenegrin coastline, Sveti Stasije, Herceg Novi, Budva, Bar and Rt Djeran which present different levels and sources of human impact. The heavy metals analyses in seawater and sediment of the Montenegrin coastline identified to be contaminated with lead the harbor Bar and Sv. Stasije, with arsenic Rt Djeran, with mercury the harbor Bar and Herceg Novi and with cadmium Herceg Novi.

The study aims to examine source apportionment of heavy metals of the surface sediments in the less than 63 micro m size fraction. An assessment of metals marine pollution was done in the sediment collected from ten locations along Montenegrin coast. The samples were dried and acid-digested and the metal contents (Fe, Mn, Cu, Zn, Cr, Co, Ni) were determined using a flame atomic absorption spectrometry. The results were compared with the literature data from Mediterranean countries.

Species belong to class Holothuriidae play significant role in the transmission of energy within the sea bottom biocoenoses. Their abundance and distribution have high impact on the biocoenoses dynamic and at the same time it can be use as indicator of the anthropogenic influence on marine environment. Data present in the paper are results of the investigation of their distribution on the Montenegrin shelf and comparison with neighboring area. Obtained results show presence of six species, and two of them are for the first time recorded for a given area.