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



in 1908. The magnitude of these accumulations is obvious from the fact that 

 they are of the same order as those of the Sargassum weed in the Sargasso Sea. 

 The accumulation of Phyllophora in the Black Sea is, possibly, the mightiest 

 accumulation of red algae throughout the whole world ocean. The bulk of 

 all the other macrophytes throughout the Black Sea is no more than 500,000 

 tons. Phyllophora occurs at a depth of 30 to 60 m, i.e. at places where macro- 

 phytes are not usually found in large numbers. On the average the density of 

 Phyllophora is 1-7 kg/m 3 , but in individual cases it reaches 13 kg/m 2 . K.Meyer 

 (1937) came to the conclusion 'that in the Phyllophora Sea we find a layer of 

 Phyllophora which appears to have been torn from its original habitat in the 

 littoral zone. Phyllophora was brought there by currents, and huge stocks of 

 it have been formed through long years'. Phyllophora, however, retains its 

 capacity for multiplication. N. Morozova-Wodjanitzkaja thinks that, like the 

 accumulation of Sargassum in the central parts of the Atlantic, the Phyllo- 

 phora accumulations of 'Zernov's Sea' have lost their genetic link with the 

 coastal Phyllophora— it has not been carried into it by currents throughout 

 the years, but has grown and increased its mass independently through 

 vegetation. 



This analogy is particularly remarkable since this huge accumulation, 

 which has no equal anywhere in the world's ocean, is formed by the brown, 

 drifting algae (Sargassum), while the other one, lying on the sea-floor at a 

 considerable depth, is formed by the red algae (Phyllophora). Small accumu- 

 lations of Phyllophora are distributed in other parts of the northwest of the 

 Black Sea ; it is found along the whole coast in small quantities. The occur- 

 rence of Phyllophora in the depths of the northwestern part of the Sea dis- 

 turbs the general course of the decrease of macrophyte biomass with depth. 

 Without Phyllophora this general course of decrease has the aspect shown in 

 Table 175. 



Table 175 



Depth, m Mean biomass of 



macrophytes in g/m 2 



The algae biomass is usually no higher than 2-5 kg/m 2 , rising rarely to 8 to 

 13 kg/m 2 . 



The specific composition of the predominant forms changes also with 

 depth ; however, the general order of the vertical change of algae remains : 

 green — brown — red {Table 176). 



Owing to the steep slope of the shores of the Black Sea the width of the 

 littoral zone occupied by macrophytes is not great, usually 3 to 6 km, and at 

 times only 1 km. It extends to 150 km only in the Odessa and Kirkinitsk Bays. 



