In this paper, we used similarity index, such as Sorensen similarity index (S), Jaccard similarity index (Cj) and Percentage Similarity Index (PSC), to show similarities and contrasts within the qualitative structure of zooplankton of various bays within Boka Kotorska. This kind of statistical overview was made for Boka Kotorska Bay for the first time, so we believe that it is a valuable contribution to recent studies on zooplankton. Tables show the results for each index individually, as well as the smallest and greatest similarity among the bays. We also presented the number of recorded species in the Boka Kotorska Bay arranged by months for three different years.

The paper presents the seasonal overview of horizontal distribution and abundance for the species of genus Oithona in Bokokotorski Bay. Three species have been recorded. Oithona helgolandica and Oithona plumifera have a wide horizontal distribution within the Adriatic Sea, while Oithona nana is a typical euritherm and eurihaline form that occupies shallow and closed coastal areas along the eastern coast of Adriatic. Also presented are seasonal oscillations and quantitative presence of these species in the Copepoda population during 2002.

In this paper, there were discussed the results of ecological investigation of the Montenerin part of the Adriatic sea during the period 1996-2003. Evaluation of the sea-water quality was done in the coastal sea. The importance of multiannual ecological investigations was emphasized, too.

In the last few years, in Montenegro there were positive movements into fulfilling the principles of sustainable marine fishery, primarily throught introducing the Law on Marine Fishing and its rules. Institure of Marine Biology in Kotor, Montenegro, in cooperations with the Ministry for Agriculture, Forestry and Water Management of the Republic of Montenegro, works on undertaking of the measures that may ensure optimal regulation of fishing. These measures were based on scientific research, particularly on the estimates of parameters of population dynamics, biomass and maximum biologically sustainable utilization of economically important species on Montenegrin coast.

Investigations of phytoplankton in the Montenegrin coastal sea through summer (June, July, August) 2003 are described in this paper. They represent continuation from the previous years, and especially from 2001 and 2002. Maximum microphytoplankton quantity is found in the area of the bay (Kotor Bay) during June 3.9 x 10**6 cell/cubic dm, with the dominance of Nitzschia delicatissima (99%). This species was found with high percentage (more than 50%) during July and August, too. Leptocylindrus minimus and Skeletonema costatum, which were dominant in the previous period, through this year were slightly presented. In the area outside the Bay of Boka Kotorska, microphytoplankton was presented with quantities cell between 10**3 and 10**5 cell/cubic dm. Mean values of microphytoplankton in the area of the Boka Kotorska Bay were in 2003 year 4.6 times higher than outside the Bay. The same ratio was found for nanophytoplankton, too.

Studies of the plankton copepods also included the area of continental shelf and the Southern Adriatic deep valley with pronounced ocean characteristics. The deep waters of Southern Adriatic are inhabited by numerous species of all depth zones, with a pronounced domination of ocean forms, similar to the Mediterranean. The quantity of copepods in the area of open surface waters shows a pronounced spring maximum of abundance. The abundance of overall copepod population decreases from the shore toward the open sea of Southern Adriatic valley, with an increase of species abundance in plankton. That area is governed by stenothermal and stenohaline conditions. The Copepoda community is characterized by stenothermic and stenohaline species. Ranges of many of these are not increased horizontally toward the northern parts of Adriatic, and the individuals carried north by water currents quickly die.