Marine biodiversity of the Mediterranean Sea: Situation, problems and prospects for future research

Mediterranean marine biodiversity has received only a fraction of the atten tion accorded to its terrestrial counterpart, despite the great cultural an d economic importance that the sea has been having for the Mediterranean co untries. A rough estimate of more than 8500 species of macroscopic marine o rganisms should live in the Mediterranean Sea, corresponding to somewhat be tween 4% and 18% of the world marine species, This is a conspicuous figure if one considers that the Mediterranean Sea is only 0.82% in surface area a nd 0.32% in volume as compared to the world ocean. The high biodiversity of the Mediterranean Sea may be explained by historical (its tradition of stu dy dates older than for almost any other sea), paleogeographic (its torment ed geological history through the last 5 my has been determining the occurr ence of distinct biogeographic categories), and ecological (its variety of climatic and hydrologic situations within a single basin has probably no eq uals in the world) reasons. Present-day Mediterranean biodiversity is under going rapid alteration under the combined pressure of climate change and hu man impact, but protection measures, either for species or ecosystems, are still scarce. To understand the role and patterns of Mediterranean marine b iodiversity, marine ecological research should: first, re-value those scien tific areas currently unfashionable with funding agencies (systematics, bio geography and taxonomy); second, start monitoring biodiversity with a long- term approach at a whole Mediterranean scale, possibly through an internati onally co-ordinated network of marine protected areas. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.