On the current status of Spongia officinalis (the sponge by definition), and implications for conservation. A review. Chapter 1

Spongia officinalis is, and will remain, the oldest nominal species of the phylum Porifera, and its name is the only one still valid among those originally described by Linnaeus. As for the biogeographic pattern, records of S. officinalis are known at the global scale, but its geographic range is probably restricted to the Mediterranean Sea. Over 500 taxa have been described under the genus Spongia, but only 41 species are verifiably valid. S. officinalis is notably plastic. Due to remodelling of morphotraits, it is difficult to describe it in a precise and accurate way and to distinguish and identify it among the many other Mediterranean and extraMediterranean bath sponge species. An irreversible depletion of the bath sponge banks of the Mediterranean Sea, due to the combined effects of over-fishing and disease, has brought several populations to the brink of extinction since the mid-1980s. The recovery of affected populations has been long and difficult, despite the sponge’s extraordinary regenerative capability due to the perennial morphogenesis of the sponge body. S. officinalis has undergone a major population decline. Since 1999 the situation has evolved dramatically for S. officinalis, and some of the few populations for which ascertained historical data are available are definitely extinct in the Mediterranean. This could be considered the beginning of a final catastrophe. On the other side of the Atlantic Ocean, due to similar feral events, the species Hippospongia gossypina has also become locally extinct from the Florida coasts, and other commercial sponge species are disappearing from the waters around Cuba. In principle, mariculture techniques are available which make it possible to perform in situ culture of sponges, as a way of dealing with this population depletion. For Spongia officinalis, it is possible that the wild populations will die out and only the “domestic” variety will survive, and that by means of farming.