Preliminary analyses of two Synechococcus ecotypes in the Adriatic Sea

Distribution and abundance of two Synechococcus ecotypes, phycocyanin-rich cells PC-SYN and phycoerythrin-rich cells (PE-SYN), in the central Adriatic Sea were studied during the two years period. The studied area included several estuarine areas, and coastal to open sea trophic gradients, covering a wide range of seawater temperatures, salinity and nutrient concentration. Both ecotypes coexisted in the studied waters with PC-SYN cells dominating during spring and PE-SYN during winter and autumn. PC-SYN showed a significant positive relationship with temperature and strong positive responses to nitrogen nutrients, whereas PE-SYN positively responded to phosphate availability. The relative ratio of phosphorus availability and total inorganic nitrogen nutrients (N/P ratio) affects the spatial distribution of the two Synechococcus ecotypes.