This study examines whether plankton of the Lagoon of Venice could be considered as a bio-indicator of areas subjected to various anthropogenic influences. This study was a two year hydrochemical and biological survey in five areas of the Lagoon of Venice, each with different environmental conditions due to pollution from urban, industrial, thermal and agricultural wastes. Phytoplankton associations did not show any promising species. In the different lagoonal areas, this community was differentiated into its major groups. In contrast, the copepod Acartia tonsa Dana could be considered as a target species in highly eutrophic areas.