Phytoplankton seasonality and exchange at the inlets of the Lagoon of Venice (July 2001-June 2002)

Exchanges of phytoplankton between the Lagoon of Venice and the Adriatic Sea were studied from July 2001 to June 2002, and synoptic surveys were performed at the Lido, Malamocco and Chioggia inlets. The phytoplankton at the three inlets showed a very similar seasonal pattern. The highest phytoplankton abundances were observed in summer and the lowest in winter. Nanoflagellate and diatom abundances (mean values 58% and 38%, respectively) dominated, dinoflagellates and coccolithophorids accounting for the remaining 4%. The abundances and alternations of species at flood and ebb tide and at the three inlets were influenced by the seasonal phytoplankton cycle. For most of the year, phytoplankton abundances are higher at flood than at ebb tide, due to the presence of neritic species, whereas only in August–October and February are abundances higher at ebb tide, due to the presence of species which have previously been described as blooming in the Lagoon waters.