480 BIOLOGY OF THE SEAS OF THE U.S.S.R. 



Nereis and others. All these forms are widely euryhaline, being found at a 

 salinity of 7 to 27% . Some of them can endure a very considerable lack 

 of salinity (down to 2 to 3-6% ) ; others, on the contrary, prefer very high 

 salinity, being found even at a salinity of 50 to 70% o . Among the Mediter- 

 ranean immigrants the most important are the groups of polychaetes (32 

 species), molluscs (22 species) and amphipods (12 species). The considerable 

 qualitative poverty of the Mediterranean fauna in the Sea of Azov is appa- 

 rent if only from the fact that of the 137 species of coelenterates of the Medi- 

 terranean, only three species live in the Sea of Azov; of the 1,451 species of 

 molluscs, only 22; of the 300 species of pelagic copepods, only 8; of the 51 

 species of crabs, only one — Brachynotus lucasii ; of the 223 species of amphi- 

 pods only 12 species, etc. 



The remains of the more salinity-loving fauna of the ancient Black Sea 

 period live as relicts in the western part of the Sea, in the Utlyuksk inlet and 

 in the Northern Sivash. As typical Black Sea relicts the polychaete Pectinaria 

 neopolitana and the mollusc Loripes lacteus may be named. The others have 

 disappeared from the fauna of the Sea of Azov ; but their shells are found 

 everywhere in large numbers, as, for instance, Venus gallina, Gastranafragilis, 

 Tapes and others. 



The ultra-haline forms so marked in the Sivash and found in large numbers 

 at salinities higher than 30% o are a characteristic element of the fauna of the 

 Sea of Azov. The most typical of them are the crustaceans Artemia salina 

 and Chironomus salinarius. 



Zoogeographical zonation 



The Sea itself can be subdivided according to its fauna in the following 

 manner : the eastern part of the Gulf of Taganrog (relict, Novo-Euxine fauna 

 with an admixture of some fresh- water species), the Sea of Azov itself and the 

 western part of the Gulf of Taganrog (with the contemporary Azov-Black 

 Sea fauna of Mediterranean origin) ; the Utlyukskyi inlet and the northern part 

 of the Sivash (a mixture of the contemporary Azov-Black Sea fauna with 

 Novo-Euxine relicts of the ancient Black Sea basin) ; and the remainder of the 

 Sivash and the saline Kuban inlet (ultra-haline forms). 



Immiscibility of the relict and Mediterranean faunas 



B. Iljin (1930), F. Mordukhai-Boltovskoy (1937) and V. P. Vorobieff (1945), 

 examining the relationship between the brackish-water and Mediterranean 

 faunas, have noted that these two faunas rarely mix with one another. The 

 brackish- water (relict) fauna is concentrated to the east of a line connecting 

 the base of Krivaya shoal with the village of Porkaton, i.e. to the east of the 

 isohaline 3-6% (Fig. 226a, b). To the west of a line from Mariupol to the 

 base of Eisk shoal (7-2% salinity) the predominance of the Mediterranean 

 fauna is just as marked. Between these two limits (3-64 to 7-25% or 2 to 4% 

 by chlorine) live the most euryhaline members of both faunas (Cyprideis 

 littoralis, Corophium volutator, Macropsis slabberi, Nereis diversicolor, 

 Hypaniola kowalewskyi and some others). The number of species and the 

 amount of biomass in this zone are much smaller than to the east or west. 



