In the period February 1989-January 1990, a sampling campaign was carried out in the Mar Piccolo of Taranto, to assess the biodiversity of unattached macrophyte populations. A stratified random sampling was performed in 20 stations variously distributed in the First and the Second Inlet. A total of 54 taxa were recorded: 15 Chlorophyta (included the rhizophytic Caulerpa prolifera), 5 Ochrophyta, 32 Rhodophyta, and unidentified colonial Bacillariophyta and Cyanobacteria. 3 species were non-indigenous (NIS). Considering the biogeographic element 2 species were Indo Pacific (IP), 18 species were Atlantic (A), 4 species were Mediterranean (M), 21 species were Cosmopolite (C), 4 species were Circum Tropical (CT) For the location of the stations see [Cecere E., Saracino O.D., Fanelli M., Petrocelli A. 1992 - Presence of a drifting algal bed in the Mar Piccolo basin, Taranto (Ionian Sea, Southern Italy). Journal of Applied Phycology 4: 323-327]