THE CASPIAN SEA 607 



Table 256 



brown and finally the green. In the Caspian Sea there is a reverse relationship 

 between these species : the first place is occupied by the blue-green and green 

 algae, the percentage of brown and red is low, and their ratio to the first is 

 even lower. The Baltic Sea ratio is somewhat similar. 



The qualitative poverty and the ratio between the separate groups of the 

 Caspian Sea macrophytes is related to the historical past of the Sea and to 

 its low salinity. Apart from the algae tabulated, on the eastern shores of the 

 Sea five species of flowering plants are widely distributed : Zostera nana, 

 Ruppia maritima, R. spiralis, Najas marina and Potamogeton pectinatus (63 

 forms in all). 



T. Shchapova (1938) thinks that the majority of brown and red algae 

 belong to the transformed Sarmatian and later Pontic flora, and that owing 

 to the occurrence of numerous and considerable losses of salinity in the Cas- 

 pian basin a whole series of marine species has disappeared, while new forms 

 of fresh-water origin have settled in. Some marine forms could have pene- 

 trated here from the west very recently. It is probable that Zostera nana was 

 one of them. The evolution of a brackish-water flora was furthered by the 

 history of the Caspian Sea ; moreover the mass development of the charial 

 algae is of particular interest. Thus the complete analogy between the Caspian 

 flora and fauna becomes evident. 



Distribution and biomass of phytobenthos. Shchapova distinguishes three main 

 groupings of bottom-living macrophytes according to the type of the sea-bed 

 soil. 



On rocky soils, chiefly on the western and eastern coasts, green and red algae 

 with the highest percentage of marine forms are preponderant. The highest 

 horizon is inhabited by Cladophora glomerata flavescens, CI. nitida and 

 Enter omorpha intestinalis. At a depth of only 0-3 to 0-4 m green algae already 

 yield their place to red ones (Laurencia paniculata, Polysiphonia elongata 

 and P. vio/acea). Among brown algae Monosiphon caspius is common here. 



On shallow sand-shell-gravel soils Zostera nana is the highest developed 

 form and, to a much lesser extent, Ruppia maritima and Polysiphonia sertula- 

 rioides. Exceptionally large growths of Zostera are found in the Mangishlak 



