Seasonal dynamics of the autotrophic community in the Lim Bay (NE Adriatic Sea)

Phytoplankton cell size structure strongly determines food webs, carbon pathways and energy flows, consequently moderating ecosystem functioning (Legendre & rASSouLzAdegAn, 1995; MArAÑón, 2009). It is generally accepted that in conditions when nutrients are sufficiently This work describes the dynamics of the autotrophic plankton community in Lim Bay in the north-eastern part of the Adriatic Sea from June 2008 to September 2009. There was an evident shift between microphytoplankton and picophytoplankton domination in summer and autumn periods, while nanophytoplankton contributed negligibly. Picophytoplankton dominated in June 2008 and September 2009 (contributing up to 84 % of the total phytoplankton biomass), while the microfraction dominated in September 2008 and June 2009 (contributing up to 97.2 % of the total biomass). The picofraction was dominated by Synechococccus in terms of abundance and biomass, with the highest abundances in September of 2009. Picoeukaryotes were not that prominent in terms of abundance or biomass, but they exceeded Synechococcus in terms of biomass in November 2008 and February 2009, and proved to be an important and consistent component of the Lim Bay phytoplankton community. Our results indicate that seasonal variability in the community structure was more affected by specific environmental perturbations occurring in Lim Bay than by availability of nutrients.