Mussels (Mytilus galloprovincialis) were collected from the locality in the vinicity of the Institute for Marine Research in Kotor (Montenegro, Yugoslavia). The concentration of Cu (copper), Cr (chromium), Fe (iron), Zn (zinc), Ni (nickel), Mn (manganese), Pb (lead), Cd (cadmium), Al (aluminium), Ca (calcium) and Mg (magnesium) were determined in whole mulles, gills, pedal muscle and in rest of soft tissues. The data obtained in this research were compared with the results reported by other investigators.

The determination of main and some biogenic and trace elements in the sea water of the Boka Kotorska Bay (Adriatic sea, Montenegro, Yugoslavia) was carried out by the atomic apsorption and emission spectrometric method (FAAS) and by the hydride technique AAS (HGAAS).

Results on sea - water quality control and level of pollution in the coastal Southern Adriatic (Montenegro, Yugoslavia) were discussed from data collected in 1997. Investigations from Boka Kotorska Bay, coastal sea up to Bojana river mouth and in front of Bojana river mouth were presented separately. For above mentioned areas, basic hydrographic parameters, as well as the level of bacterial contamination were examined throughout the year (1996/1997 period). In Kotor Bay, which is the shallowest and exposed to the strongest land - based sources, as in the Tivat Bay, some changes influenced by anthropogenic eutrophication were already found.

In order to determinate the concentration of elements: K, Ca, Na, Mg, Cu, Pb, Cr, and Cd in sea water and seagrasses Posidonia oceanica and Cymodocea nodosa sampling were done in the area of the Boka Kotorska Bay (Adriatic sea, Montenegro (Yugoslavia)). For majority of these elements variability of contents in the samples was great, but in the range of expectations. The concentrations of Pb and Cr in the seagrasses were higher from values in literature. Because of bioaccumulation and biomagnification of these metals, we have to investigate causes of these higher concentrations and possibility of toxic effects on the seagrasses and other organisms.

During complex studies of phytoplankton, the role of particular phytoplankton groups was examined, as one of important indicators of eutrophic processes in the Bay of Boka Kotorska (Adriatic sea, Montenegro (Yugoslavia)). Throughout summer 1999, investigations have been performed at representative locations (Kotor, Tivat and Hercegnovi bays) at the depths of 0, 5, 10 and 20 m. Maximal values of microphytoplankton were found in Kotor Bay in July (2.1 x 10**6 cells/cubic dm). In Tivat Bay, maximal values of microphytoplankton were found in June, although they were ten times lower (2.4 x 10**5 cells/cubic dm). In the Bay of Hercegnovi, mean values were lower, while maximal quantity of microphytoplankton was found in August (2.6 x 10**3 cells/cubic dm). In the Boka Kotorska Bay, the maximal percentage of 95% of the group Bacillariophyceae was found in the most productive surface layers at the depths of 0 and 5 m. The impact of eutrophication was the most visible in the Kotor Bay. It decreased towards the open sea. Diatoms populations (Bacillariophyceae) were dominant in the Bay, while the participations of other groups is insignificant. Consequently, it means that Bacillariophyceae are the most adapted group to the eutrophic conditions of the Boka Kotorska Bay.

In this work, we were investigated level and source of trace elements in industrial and sea waters in Bokakotorska Bay (Adriatic sea, Montenegro, Yugoslavia). The ranges concentration in (microgram/cubic dm) in seawater are as follows: Hg (0.1-0.4); As (0.1-0.9); Pb (2.3-10.0); Zn (3.0-12.0); Cu (2.3-8.4); Cr (0.8-3.0); Cd (0.1-1.0); Ni (0.9-3.0); Mn (0.2-0.5). The average levels of trace elements in the samples collected from industrial effluents of factory ILK were 110 - 16500 times higher than concentrations of trace elements in other industrial effluents.

Reproduction and planktonic phase of life of edible shellfishes, Mytilus galloprovincialis Lamk. and Ostrea edulis L. were the subject of the investigations. Biological and ecological characteristics of mentioned species have been studied in Boka Kotorska Bay (Adriatic Sea), Montenegro (Yugoslavia), having in mind data from the Adriatic Sea and Mediterranean. Beside, some localities from Boka Kotorska Bay, conveniet for their rearing, were described , too. A period of their appearance in plankton was considered before all.

Studies of phytoplankton in the Montenegrin coastal sea (Adriatic Sea), Montenegro (Yugoslavia), have been done in August and September 1998. Simultaneously, investigations were carried out in the area of Boka Kotorska Bay (Kotor and Tivat Bays) and outside the Bay, i.e. in the zone exposed to the influence of the open sea (Petrovac and Budva). It was found that the density of microphytoplankton is higher during summer, than in the autumn. So in the summer-period, as a consequence of stronger eutrophication process, mean-value of microphytoplankton density was 10**5 cells/cubic dm, and in autumn 4 x 10**4 cells/cubic dm. On the contrary, mean-value of nanophytoplankton density was higher in the autumn (5.2 x 10**6 cells/cubic dm) than in summer (3.5 x 10**5 cells/cubic dm), being a consequence of a decreasing eutrophication during colder period of the year. Having in mind the direct influence of the open sea outside the Bay, it is intelligible that population density of both phytoplankton size-fractions is lower along the Montenegrin coast, than in the Boka Kotorska Bay (Montenegro, Yugoslavia).