7 × 108 cells L− 1) in an estuarine area of the NW Adriatic during the summer ( Bernardi Aubry et al. 2006). Picocyanobacteria play a substantial role in nutrient-richer transitional ecosystems,

and they may even become the prevailing fraction of the phototrophic plankton at these sites ( Paoli et al. 2007). This suggests the potential use of picophytoplankton as a functional biomarker of the higher trophic status of coastal marine environments. Analysis of phytoplankton size-spectra has already been used as a tool in the evaluation of transitional water bodies in the Adriatic Sea, but it was limited to taxa within the INCB024360 purchase nano- and microphytoplankton size range ( Sabetta et al. 2008). However, the study by Bec et al. (2011) found differences between the relative and absolute importance of the prokaryotic and eukaryotic components among the picoautotrophs along the trophic gradient in Mediterranean coastal

lagoons. Those authors suggested that the numerical dominance of picocyanobacteria could reflect oligomesotrophic conditions in marine coastal waters. Because of their small size and high surface-to-volume ratios, these appear to be more competitive than picoeukaryotes and the larger phytoplankton in acquiring nutrients in resource-limited Sorafenib nmr systems. This dominance could be related to the ability of Synechococcus to acquire phosphorus when concentrations are very low (

Bec et al. 2011 and the references therein), because phosphorus is the limiting nutrient for phytoplankton growth in the whole Mediterranean Sea ( Siokou-Frangou et al. 2009), including Boka Kotorska Bay ( Krivokapić et al. 2011). Picoeukaryotic algae were recorded in the Bay in all seasons in small numbers, but as they contain more carbon per cell, their contribution was better reflected in terms of carbon biomass. The Oxymatrine stable but negligible importance of the picoeukaryotic contribution has been demonstrated in other studies in coastal transitional areas of the Adriatic Sea ( Vanucci et al. 1994). It has been reported that their relative importance with regard to abundance and biomass generally increases with increasing trophic status of the marine system, as they are the most competitive group among the pico- and nanophytoplankton ( Bec et al. 2011). This was not the case in our study, however; apparently, the Bay’s trophic status is still not high enough to promote their greater development. The dominant species in the phytoplankton assemblages found in this study display preferences for nutrient-rich conditions (Pucher-Petković and Marasović, 1980 and Revelante and Gilmartin, 1980) and are found in higher abundances in only a few moderately eutrophic environments in the Adriatic Sea (Cetinić et al., 2006 and Bosak et al., 2009).