Biogeographia vol. XXIV - 2003 (Printed October, 31st 2003) Marine biogeography of the Mediterranean Sea: patterns and dynamics of biodiversity Mediterranean Sponge Fauna: a biological, historical and cultural heritage ROBERTO PRONZATO Dzp. Te.Ri5., Uiziversitiz 512' Genowz, Corso Europa 26, 1-1 6132, Genova (Italy) e—mzzi[: pronzzzzfo @dz}nferi5. umge. it Key words: biodiversity, Fauna protection, fishery, bioactive metabolites, sponge farming. SUMMARY At the end ofthe last century (year 2000) the Mediterranean sponge species were 605: over 40% are endemic, North Atlantic affinities are 20%, South Atlantic ones are 6%. Lessepsians migrating species are more than 30 (about 5%). Mediterranean Sea was deeply investigated in the past, in spite of that the discovery of new species, or genera, is not a rare event. The species richness of Mediterranean sponges is under pressure and losses are possible because of epidemic diseases and over—fishing of bath sponges. During the last decades the number of species that are actively harvested is dramatically increasing; this tendency in absence of any knowledge on sponge population distribution and density, could lead to local extinctions. INTRODUCTION In a world—wide synthesis on sponge biogeography (Soest, 1994) are examined over 11.000 papers, all data on systematic and faunistic of over 7.000 species, belonging to about 1.200 genera. From this study results that 552 species belong to the Western Mediterranean basin while 194 are present in the Eastern one. This record, compared with the sponge species richness of other 34 geographic areas, shows that only Caribbean-Centro—American (640 species), Sino—]apanese (589 species) and Indonesian (965 species) Seas are populated by a more diverse sponge fauna. In a successive study, performed with cladistic methods (Soest, 1998) the very low affinity of the Eastern Mediterranean sponge fauna with any other Sea of the World is evidenced. As for the Black Sea almost no data are available in the scientific literature, as a consequence no comparison can be done. The number of Mediterranean sponge species has continuously increased up today; first data are reported from the 13th edition of Systema Naturae (Linne, 1789), from that moment successive papers report a continuous and constant