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



(1924), A. Derzhavin (1925) and others, independently of the Azov-Black 

 Sea expedition. 



Third period 



Very valuable and thorough quantitative investigations of the fauna of the 

 Sea of Azov have been carried out in the last few years by the Azov-Black 

 Sea Institute of Fisheries and Oceanography and the Don-Kuban Fisheries 

 Station. Among these works the most important from our standpoint are those 

 of V. VorobiefT on the benthos of the Sea of Azov (1944) and on the Sivash 

 fauna (1940), of A. Okul (1940) on the plankton of the Sea of Azov, of F. Mor- 

 dukhai-Boltovskoy (1937) on the bottom-living fauna of the Gulf of Taganrog, 

 and of V. Maisky (1940) on fish census. The work of A. Zhukov (1938) on 

 the chemical conditions of the Sea, which hitherto had remained almost un- 

 examined, must also be noted. All these investigations have been carried out 

 in recent years. 



In connection with the changes in the Caspian Sea conditions, as a result 

 of hydro-power construction on the river Don, detailed investigations of the 

 conditions and the biology of the Sea of Azov have been carried out by 

 (A. Karpevitch, 1955, 1957; M. Zheltenkova, 1955; T. Gorshkova, 1955; 

 V. Datzko, 1951; G. Pitzik, 1951; G. Pitzik and A. Novoshilova, 1951; 

 I. Stark, 1951, 1955, 1956; E. Yablonskaya, 1955, 1957; V. Maisky, 1955; 

 F. Mordukhai-Boltovskoy, 1948, 1953, 1960; A. Novoshilova, 1955, 1958). 



III. PHYSICAL GEOGRAPHY, HYDROLOGY AND HYDRO- 

 CHEMISTRY 



Situation and size 



The Sea of Azov, extending to 45° 17' N latitude and from 34° 19' to 

 39° 18' 30" W longitude is a very shallow water body (Fig. 222), which is 

 greatly diluted in its eastern part by the rivers Don and Kuban and made 

 more saline in its western part on account of evaporation. The Sea of Azov 

 is connected with the Black Sea by the narrow Kerch Strait, and it can be 

 regarded as a broad inlet of the Don. On the northwest the Sea of Azov is 

 connected with the Sivash or Putrid Sea by the narrow Genichensk Strait 

 (120 m). The surface area of the Sea of Azov is 38,000 km 2 (without Sivash) ; 

 of this total 5,640-6 km 2 is the area of the Gulf of Taganrog. The surface area 

 of the Sivash is 2,630 km 2 . 



Bottom topography 



The greatest depth of the Sea of Azov is only 13^ m. The average depth of 

 the Gulf of Taganrog is 4-7 m, that of the Sea of Azov without the Gulf of 

 Taganrog — 7-2 m, and with it 6-8 m. The total volume of the Sea is 320 km 3 . 

 The Sivash is very shallow, its greatest depth being no more than 3-6 m. A 

 shallow zone of less than 5 m deep (Fig. 222) forms a narrow strip off the 

 coast. Depths of 5 to 10 m encircle the body of water, except for the southern 

 part of the Sea of Azov, occupying 42-7 per cent of its area. Depths of 10 m 



