A review of the Mediterranean Sea sponge biogeography with, in appendix, a list of the demosponges hitherto recorded from this sea

Abstract

Biogeographia vol. XX I V - 2003 (Printed October, 31 st 2003) Marine biogeography of the Mediterranean Sea: patterns and dynamics of biodiversity A review of the Mediterranean Sea sponge biogeography with, in appendix, a list of the demosponges hitherto recorded from this sea MAURIZIO PANSINI*, CATERINA LONGO** *Dz]). Te. R23q. Dzpartimenro per lo Stuzlio del Territorio e del/e me Risorse, Universizil di Gmowz, Corro Europa, 26, 146132 Gmamz (Italy) “Dzyzarrinzenta di Z00/ogizl, U'm'z/errz't2z di Bari, Via Orzzlmmz 4, 1-7 0125 Bzzri (Italy) Key words: porifera, distribution, biogeography, Mediterranean history, species list. SUMMARY The total number of porifera species hitherto recorded from the Mediterranean Sea is 649. Demospongiae are 597, Calcarea 44, Hexactinellida 8. The demosponge distribution, studied on fifteen Mediterranean zones is not uniform, even if not proportional to the number of taxonomic studies performed in each area. The highest faunistic afiinities are among the southern and eastern parts of the basin, where seawater temperature is relatively warmer. The present day Mediterranean demosponge fauna is formed by a large nucleus ofendemic species (48,2 %). by cold water (19,8%), temperate (12%) and warm Water (5,7°/o) species. Cosmopolitan species (93%) are probably over estimated, whereas few species migrated from the Red Sea. The present day composition and biotic aFfinity of the Mediterranean sponge fauna can be explained, at some extent, by the geological history of this basin. Most of the paleomediterranean fauna did not survive the messinian salinity crisis but a small number of possible Tethyan relics. The demosponge list in appendix is updated according to the Systema Porifera, the revision of all the extant sponge genera published in October 2002. INTRODUCTION} Global changes and human pressure are certainly affecting marine ecosystems, probably reducing the available habitat. This is particularly true for semi—closed basins as the Mediterranean Sea. There is also a general concern about the decline of biodiversity, which contributes to promote research on this topic. Biodiversity and biogeography of Mediterranean sponges have been studied in the past by several authors. Vacelet (1980a‘) considered the afiinities of this fauna; Pulitzer—Finali (1983), Drai (1985), Pansini (1995) produced lists of species; Pansini (1992, 1996) updated the existing data and analyzed the Italian sponge fauna; Maldonado and Uriz (1995) compared the sponge fauna ofAlboran Island with those of-five other Atlantic—Meditertanean Islands, using the biotic affinities among these archipelagos to test Various hypotheses on the origin of the