THE SEA OF AZOV 495 



The qualitative composition of the macrophytes of the Sea of Azov is consider- 

 ably impoverished as compared with the Black Sea. Instead of the 221 species 

 of green, red and brown algae of the Black Sea there are no more than 25 or 

 30 species in the Sea of Azov. The amount of algae decreases markedly as one 

 moves eastwards, and at the entrance to the Gulf of Taganrog red algae are 

 not found. In the Sea of Azov among the red algae the most widely distri- 

 buted are Ceramium diaphanum, Polysiphonia opaca and P. variegata ; among 

 the green species, Enteromorpha and Cladophora. The macrophytes populate 

 only a narrow band along the shore of the Sea of Azov. Apart from this 

 among the flowering plants Zostera marina, Z. nana (minor), Zannichelia 

 pedunculata and Potamogeton marinus are common in the Sea of Azov. 



Continuous macrophyte beds are rare in the Sea of Azov, and only in the 

 Utlyuksk inlet and in the northern Sivash are there abundant growths of 

 Zostera, which are exploited commercially. According to V. Generalova the 

 maximum biomass of bottom-algae of the Utlyuksk inlet is 22-4 tons, and 

 that of calcareous plants 69-3 tons per hectare. According to the data of 

 M. Kireeva and T. Shchapova (1939) in those areas the amount of Zostera 

 occupying an area of 9,500 hectares is 25,000 tons dry weight. 



According to V. Generalova (1951) Zostera forms about half of the total 

 mass of water macrophytes in the Sea of Azov, red algae form 35 per cent and 

 the green 1 5 per cent. Commercial stocks of macrophytes of the northwestern 

 part of the Sea of Azov are small (Table 202). 



Qualitative composition of zoobenthos (Fig. 237). We do not possess sufficient 

 data for a complete list of species of the bottom-fauna of the Sea of Azov, 

 but we can make use of the incomplete list drawn up by F. Mordukhai- 

 Boltovskoy (1960). This list includes (with unimportant additions but without 

 Protozoa) 292 invertebrate species and sub-species (Table 203). 



The crustaceans occupy the first place by the richness of their specific 

 composition and the number of specimens per unit area (about 3,670), but 

 as regards biomass the bivalves are considerably superior to the rest. The Sea 

 of Azov may be truly called the mollusc sea, or the Cardium-Syndesmya 

 sea, as the Baltic Sea can be called the Macoma sea; this may be illustrated 

 by the data given in Table 204. 



The peculiar conditions of the Sea of Azov— its salinity lower than that of 

 the Black Sea, its marked seasonal fluctuations of temperature, its long 

 winter and shallow waters — lead to a definite selection of forms from the 



