RECHERCHES SUR LE PERIPHYTON À DIATOMÉES DANS UN VIVIER DE LA LAGUNE DE VENISE (MAI 1984–MAI 1985)

Abstract

In view of the important role played by the periphyton in the primary productivity of brackish environments, a research has been carried out on benthic diatoms colonizing artificial substrates. For this purpose, slides with different orientations (vertical or horizontal) were kept submerged for about 30 days in two stations of ‘Valle Dogà’ (a Northern fish pond of the Venice Lagoon). Qualitative and quantitative (i.e. the cover estimated as cells.cm⁻²) analyses as well as evaluations of the biomass were made on the diatom populations. The more representative and constantly present forms were three species belonging to the genus Cocconeis (C. molesta, C. placentula, C. scutellum). Other species (Achnanthes exigua, Amphora exigua, A. veneta, Licmophora cf. biplacata, Navicula gracilis v. recurva, Synedra tabulata) were only sometimes abundant. This study, together with one of the phytoplankton carried out in the same period, provides knowledge about the trophic chain in these environments.