The river Gvozdac (Serbia, Yugoslavia) is a small hill water current. It is situated on the mountain Goc and it belongs to the river basin of the river Ibar. During 1965, water micro-reservoir "Gvozdac" on the river Gvozdac was built for the hydroenergetic purposes, with the capacity of about 30,000 cubic meter and the maximum depth, in the present situation of about 2.5 m. Algological and saprobiological enquires have been performed on the water micro-reservoir, on the very river Gvozdac, on the river Ribnica and on some smaller stagnant waters on the given area, in the period between 1988-1994. The analysis have been shown that under the influence of antropogenic factors changes became apparent in the confluence and structure of algae flora as well as a degradation of water quality. The example of water micro-reservoir on the river Gvozdac indicates the destructive processes which are being developed in water micro-reservoirs and which should be stopped, as the significance of the small stagnant waters are not only in keeping and improvement of qualities of greater aquatorials and water tributaries of the river basins but also in the storing of biodiversity of aquatic assotiations in river basins (as well as in algae flora as one of the components).

In the scope of the Program of surface water quality examinations in the Republic of Srpska (Bosnia and Herzegovina), hydrometric measurements and water quality examinations had been realized, where zooplankton and microzooperiphyton researches have been performed. Sampling were performed in the period from 6th to 20th May 2000, at 13 water courses with taken in total 21 samples. In qualitative structure of examined fauna, Rotatoria, Cladocera and Copepoda groups were treated, with ascertained in total 109 taxa from 41 genus. In qualitative structure periphyton taxa are predominant. On the basis of bioindicatory species structure it is noticed that dominant species are oligasaprobic and oligobetamesosaprobic character.

The investigations of the macrozoobenthos of the Crvena Reka river (Serbia, Yugoslavia), left tributary to the Nisava river, were performed during July in 1999. Samples were collected from 15 localities, from the spring of the Crvena Reka river (originating from Toponicka and Vetska rivers) to the lower course, the aim being to investigate the diversity of macrozoobenthos of these running waters which had not been investigated. The community of macroinvertebrates of the Crvena Reka river and the streams, which make it, consists of 54 determined taxa (at species and genus level) from 16 animal groups. Larvae of Ephemeroptera and Trichoptera have the greatest diversity, each having ten determined taxa. The middle course of the Topnicka river (locality T4) is characterized by the greatest diversity (25 taxa), while the springs (due to constant ecological parameters) have poor diversity with two and one determined taxa in locality V1 and V2, respectively. The water quality of the investigated river and streams, which make it, on the basis of the results of saprobiological analysis, is of beta-mezosaprobic quality, i.e. second class of quality in most localities.

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.

Monitoring of phytobenthos was performed seasonally, on five locations of Montenegrin coast for the purpose of environmental monitoring. Locations with highest biodiversity were Budva and Stari Ulcinj, while the poorest one was Kotor. Regression of seagrass Posidonia oceanica was observed on the Krasici location.

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.

Every country must to concern the biodiversity of flora and fauna, especially in ecosystems rich with endemic and relict species. Such ecosystem is the Lake Ohrid.

In this paper, we present the results from both quantitative and qualitative composition of the Gastropod fauna from Lake Ohrid (profile HBZ-Radozda) with their vertical distribution in littoral and sublittoral region of the lake. The results of our investigations shows some changes in biodiversity and the density of gastropod communities that settle this profile, compared with the investigations made 30 years ago.

In this paper are presented the investigation of macrophytic vegetation along Macedonian shore of Lake Ohrid (Radozda-Sv.Naum). The meterial were collected from 59 localities. The results of investigations show that in investigated localities were evidenced 25 different plant species. The number of macrophytic species in different localities vary from 2 to 18 macrophytic species. The differences in the number of macrophyte species are most due to the different ecological conditions in the investigated localities: temperature, light regime, type of soil, configuration of the lake bottom, water level, nutrient amount etc.

The paper presents the results of diversity and distribution of thermophilic species of echinoderms in the continental shelf on Montenegro coast. The data show that explored area inhabited by eight species of which the sea cucumber Holothuria (Platyperona) sanctori for the first time is recorded and is new species for the fauna of Montenegro. Based on the fact that climate change affects the temperature rise of the sea water, especially the coastal area, the aim of this study was to determine the presence of thermophilic species of echinoderms, which can be the basis for further monitoring and tracking changes in the benthic biocoenosis of the southern Adriatic.