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



Strelka, behind which is situated the estuarine lake of Sivash with its greatly 

 increased salinity. This lake is connected with the Sea by the Genichensk 

 Strait. 



The coasts of the Sea of Azov have two exceptional characteristics. A series 

 of five narrow shoals, stretching out from the coast into the Sea at an angle 

 of about 45° in a south-southwesterly direction, is situated in the north. The 

 length of these shoals increases from east to west ; the biggest is more than 

 50 km (Fedotova shoal with Biryichy Island). Their unusual formation is 

 connected with the marked prevalence of easterly and northeasterly winds, 

 owing to which the resultant of the action of the waves is oriented almost 

 parallel to the present coast (A. Aksenov, 1955). The cause of this unusual 

 orientation of the shoals is due to the deposits being shifted at maximum 

 speed at an angle of about 45° to the direction of the waves. 



The second characteristic of the shores of the Sea of Azov is that the basic 

 material of accumulated forms consists almost exclusively of shell gravel 

 brought out to the coast. The shoals on the eastern shore consist entirely of 

 marine shell gravel. This rare phenomenon is connected, first with the very 

 high productivity of the bottom-fauna, and secondly with the instability of the 

 coastal loess which, when broken down, is too fine to be deposited on the shore. 



IV. FLORA AND FAUNA 

 General characteristics 



We know of no other sea in the world which can be compared with the Sea 

 of Azov in the extreme intensity of its productive processes. This is the result 

 of a whole series of factors, although there are some which have a reverse 

 effect (for example, the occurrence at times of a pronounced oxygen deficiency 

 and the formation of hydrogen sulphide in the bottom layers). Knipovitch 

 rightly includes among the conditions contributing to the high productivity 

 of the Sea of Azov : its shallowness, which facilitates the return of nutrient 

 substances from the bottom into the water ; an adequate exposure to sunlight 

 of the whole water-column (in spite of its low transparency) ; favourable condi- 

 tions for mixing and aeration and, finally, the large amounts of inorganic and 

 organic matter brought in by the rivers, both in solution and in suspension. 



Knipovitch also notes that the lowered salinity greatly affects the qualitative 

 composition of the flora and fauna but does not hinder its very rich quanti- 

 tative development. 



The following should be added to these considerations. If the Sea of Azov 

 were widely connected with the Black Sea and formed a part of it, like for 

 instance the northwestern part of the Black Sea, its productivity would un- 

 doubtedly be less even though the amounts of nutrient salts carried from the 

 shore and detritus were the same. All nutrient substances are accumulated 

 in the Sea of Azov and, except for a comparatively negligible loss through the 

 Kerch Strait, they are not carried out of it. We see something quite different 

 in the area of the Black Sea mentioned above : nutrient substances and detritus 

 are carried away in large quantities from the shallow coastal regions into the 

 adjacent deeper parts, which considerably lowers the biological yield of those 

 shallows. 



