, 1989, Cetinić et al., 2006 and Burić et al., 2007). Nevertheless, freshwater phytoplankton species such as Pediastrum spp. were occasionally observed in the samples, probably due to local freshwater input from small rivers and springs, which is greater mainly in the winter and spring. The dominance of the diatom S. marinoi in the spring and winter resulted in microphytoplankton dominance in total carbon biomass above the halocline. Skeletonema blooms were a distinct feature of the Bay, clearly distinguishing its

phytoplankton assemblages from those in adjacent waters. The species is reported to be one of the dominant species in the nutrient-richer areas ( Revelante and Gilmartin, 1976 and Viličić et al., 2009), where it usually exhibits

marked seasonal behaviour, forming blooms PI3K inhibitor above the pycnocline in the late winter ( Totti et al., 2005, Bernardi et al., 2006 and Pugnetti et al., 2008). It is also found in other riverine water-influenced and nutrient-rich environments ( Blanc et al., 1975, Thompson and Ho, 1981, Spies and Parsons, 1985 and Morozova and Orlova, 2005). In the waters surrounding the investigated Bay its presence is detected sporadically, but even then in very low abundances ( Socal et al., 1999 and Rubino et al., 2009). It has recently been discovered that different strains of S. marinoi can tolerate a wide range of salinity ( Saravanan and Godhe, 2010 and Balzano et

al., 2011), which is in accordance with our findings of the species’ check details greatest abundance in surface samples (salinity < 5). Thus, its mass development in the surface waters of Boka Kotorska Bay can be attributed to the competitive advantages of this species over the other marine phytoplankton found in the water column in this period in view of its ability to flourish in conditions of low salinity and lower temperatures. In addition, bloom-forming species like S. marinoi are characterized by inherently high growth rates and can efficiently exploit nutrients, the levels of L-NAME HCl which are higher, especially in the layer above the halocline in the Bay ( Smayda 1998). The influence of the vertical salinity gradient in the phytoplankton distribution is also clearly perceptible in other phytoplankton groups. Cryptophytes and Dinobryon sp. correlated positively with nutrients and negatively with salinity, confirming their preference for the upper, nutrient-rich and less saline layer. The mixotrophic chrysophyte Dinobryon sp. ( McKenrie et al. 1995) and cryptophytes were found in high cell concentrations in the surface layer during spring. Their development was probably favoured by the higher inorganic nutrient concentrations as well by the release of organic matter by diatoms at this stage of the Skeletonema marinoi bloom.