Phytoplankton community composition and distribution in an eutrophic coastal area (Venice lagoon, Italy)

Abstract

          We investigated the phytoplankton in the central area of the Venice lagoon in the 1990s. Water samples were collected at 46 sites in June 1993 and June 1998 and at four stations every month from November 1998 to October 1999. Collected data include community composition, cell abundance, and cell bio-volumes, estimated with an inverted light microscope. Cell abundance distribution maps display mean (6.9 x 10⁶ and 2.5 x 10⁶ cells dm^-3 in June 1993 and June 1998, respectively) and peak values (151 and 16 x 10⁶ cells dm^-3 in June 1993 and June 1998, respectively). The reasons for differences in blooming taxa were investigated by processing environmental variables of the most abundant taxa by Canonical Correspondence Analysis. The environmental parameters that most affected the species spatial distribution were salinity and temperature in June 1993 and salinity and water transparency in June 1998. Phytoplankton temporal trends confirmed the spatial distribution: the blooming period was in June and the highest cell abundances occurred close to the mainland.