Marine research at CNR
oxygen saturation showed an opposite pattern by decreasing near the bottom. KO station was the only one that showed high values of fluorescence at the surface (1.4 A.U.) in correspondence to the maximum of oxygen (101 %), and in the middle layer (1.2 A.U. at 22 m depth) coupled with the minimum oxygen values (89.4 % at 25 m depth). The minimum of oxygen saturation below the layer of the maximum of the fluorescence indicated a probable predominance of mineralization process rather than a primary production process and the absence of important vertical mixing. The waters occurring in station 4 (Figure 3) showed the same charateristics of the Adriatic coastal waters. Salinity was constant enough from the surface to the bottom with a slight increase along the water column (from 38 to 38.8). A surface layer began warming as expected in this period [29, 30, 31]. Fluorescence and oxygen profiles showed the maximum values at 50-80 m where light conditions were good for the primary production [32, 33]. In June, the temperature increased in all the five stations in particular the 30 m layer from the surface. This increase in respect to previous period was around 7 °C (in HN and 1 station) and 9 °C (in TV and 4 station). The salinity increased at the surface by only 1-2 points in all the stations and this was probably due to the poor river runoff in the summer period. The oxygen saturation presented lower values (less than 5-10 %) compared to May because during the summer period the vertical mixing was normally reduced [34]. The KO station showed some differences in respect to the other ones. Oxygen saturation increased to 7-8 % in respect to May. This increment was coupled with the fluorescence concentration decrease and it was not probably imputable to the primary pro-
duction. In respect of May, more changed were observed in fluorescence and oxygen saturation at the KO, TV and HN stations. In particular, the KO station showed, as observed in May, major differences in respect to the other stations.
3.2
CDOM, Biochemical and Biological characteristics
Table 1 shows the values of CDOM and biochemical parameters (nutrients, chlorophyll a) and phytoplankton (phytoflagellates, diatoms, dinoflagellates and others nanoflagellates) in the two months. Microplankton community was dominated by diatoms, nanoflagellates both autotrophic and heterotrophic and dinoflagellates with lower abundances but high specific diversity, as previous observations documented by Vuksanovich and Krivokapic [35] in Boka Kotorska Bay. The nutrient and phytoplankton concentrations showed a different distribution at the KO station compared to the others. In particular, orthosilicate concentrations and diatom abundances showed different patterns. In May, the silicate concentrations were about 5 µM at the KO station coupled with a diatom abundance of about 3000-3500 cell·l−1 . In June an increment of cell number of diatoms at the 10 m depth (9040 cell·l−1 ) and an uptake of orthosilicates that reduced to 0.54 µM was observed. The other stations inside the bay and in open sea showed opposite behaviour. In these stations, the orthosilicate concentrations increased by about 1 µM in respect to May and the diatom concentrations reduced drastically (e.g. from 3900 cell·l−1 to 380 cell·l−1 at the surface of the TV station). In June the Kotor bay seems to 7