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 investigation of benthic algae of the river Rasina. During April, 2001, it was determined 110 algal taxa from the divisions Cyanophyta, Bacillariophyta and Chlorophyta, which indicate the high biodiversity of algae in this river. With 97 algal taxa, Bacillariophyta is dominant. The community of benthic algae is typical for this kind of aquatic ecosystem during the spring period. Great number of algal bioindicators of highly polluted water indicates the presence of high concentration of organic compounds in this aquatic ecosystem.