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The Main Biogeographical Features and Problems of the Mediterranean Fish Fauna
Vol. 1964, No. 1 (Mar. 26, 1964), pp. 98-107
Stable URL: http://www.jstor.org/stable/1440837
Page Count: 10
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Strictly considered, omitting the adjacent part of the Atlantic Ocean and the Black Sea, the Mediterranean fish fauna comprises about 550 species. Although long known, these fishes need further researches, especially in respect to their geographical distribution and differentiation. They are dispersed according to several distributional patterns. The largest group is Atlantic (Boreal, West African, or Amphi-Atlantic). Other species are endemic or cosmopolitan. Some, especially those that have been found in scattered regions of the world, pose unsolved problems, both systematic and biogeographical. Deep-sea fishes are scarce; four species only have been found below 2,000 m. The Mediterranean is usually defined as a warm-temperate sea, but it comprises several basins, in which the conditions differ more or less widely, and between which some of the faunistic features differ remarkably. These differences are evident in both west-east and north-south directions. Tropical fishes occur mainly in the southern region and in the eastern basin. In this basin there are now about 30 Indo-Pacific species, which have immigrated from the Red Sea through the Suez Canal. A number of Atlantic species, even Boreal ones, occur either regularly or occasionally in the western basin. Several Mediterranean fishes are rare or absent in the Adriatic. Some species that occur in both the Mediterranean Sea and the Atlantic Ocean exhibit geographical differentiation between the two areas. Furthermore, within the Mediterranean, related races or vicarious species occur in the various basins of the Mediterranean, which represents a center of speciation. It is quite probable that such littoral types as blennioids or gobioids will exhibit further differentiation, ecological or geographical, when they have been subjected to more critical analysis.