THE SEA OF AZOV 



483 



a£{ phytopfanxton 



\Matomeae 



PeiLdineae 



Cyanophyceae 



тиупгнуннххш iitwririiniixxuxii иимг/ютжхлт// iwwmi.nu'x.xxiin uwr.ri /// \nnixx xi xu 

 Fig. 228. Seasonal changes of certain groups of phytoplankton in the Sea of Azov 



(Okul). 



There are only 32 species of mass forms among them. Among the Blue- 

 green algae there are : Microcystis feruginosa, Aphanizomenon flos aquae, 

 Nodularia spumigena f. typica, var. lato-rea, Anabaena knipowitschi, A. hassalii 

 var. macrospora; among the Protozoa, Silico-flagellata : Ebria tripartita; 

 among the peridineans : Exuviella cordata, Proterocentrum micans and Gleno- 

 dinium danicum; among the diatoms: Skeletonema costatum, Thalassiosira 

 nana, Coscinodiscus biconicus, Leptocylindrus danicus, Rhizosolenia calcar- 

 avis, Rh. radiatus, Chaetoceros subtile, Biddulfia mobiliensis, Ditylium bright- 

 welli and Thalassionema nitzschioides. 



Phytoplankton biomass. The relative significance of phytoplankton in the 

 productive processes is comparatively high, owing to the very weak develop- 

 ment of coastal vegetation. As regards mass the main role in the phyto- 

 plankton is played by the diatoms (about 55 per cent of all the phytoplankton 

 in the whole of the Sea), the peridineans (about 41-2 per cent of all the phyto- 

 plankton, chiefly in the open sea), and to a much lesser extent by the algae. 



months /и ,y. v V! V // v/ /i i X x xi xil III IV i VI VI/ VIII IX X Я Ml 



Fig. 229. Quantitative relationship between the phyto- and zoo-plankton of the Sea 

 of Azov in various seasons of the year (Okul). 



