The development of benthonic phytocoenosis on artificial substrates in the ticino river.

Changes in the taxonomic composition, chlorophyll a concentration, dry weight, percentage organic carbon and nitrogen and several indices of diversity, including "Margalef's index" were followed during the development of phytobenthonic communities on glass slides. These data suggest that, in this environment, the algal community resembles the nearby natural community after 4 weeks. The taxonomic development can be divided into two phases. During the first 2 weeks the phytocoenosis is dominated by a rather diverse and variable diatom assemblage. Later Cyanophyta dominate. The diversity decreases during colonization as reflected by all indices considered.