456 



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



Caspian species, while 63-8 per cent of the last one consists of marine forms. 

 A. Ostroumov had already pointed out in 1897 that the animal population 

 of the seaward area of the inlet consisted mainly of marine species, which 

 gave place to the ' Caspian ' and fresh- water species farther up the inlet (Figs. 



Fig. 218. Distribution of 

 marine, relict and fresh-water 

 bottom biocoenoses in the 

 delta and the inlet of the 

 Dniester. Biocoenoses: 1 

 Fresh-water; 2 Relict; 3 

 Marine or relict depending on 

 salinity; 4 Marine (Markov- 

 sky). 



70 

 65 

 60 

 55 

 50 

 45 

 40 

 35 

 30 

 25 



го 



/5 

 10 



5 

 



Fig. 219. Percentage relationship 

 of the number of 'Caspian' 

 fresh-water and marine species 

 of bottom animals in various 

 zones of the Dniester inlet (Mar- 

 kovsky). 1 Percentage, 'Caspian' 

 species; 2 Percentage, fresh- 

 water species; 3 Percentage, 

 marine species. 



218 and 219). Markovsky distinguishes nine bottom biocoenoses in the Dnie- 

 ster inlet with the following dominant forms: {Pontogammarus maeoticus, 

 Corophium volutator, Nereis sp., Corophium nobile, Dikerogammarus, Dreis- 

 sensia polymorpha, Monodacna, Clessiniola variabilis, Micromelania lincta, 

 Lithogliphus naticoides, Syndemya ovata and Cardium), i.e. the 'Caspian' 

 species are again predominant. Markovsky records in all more than 100 

 species of bottom and benthopelagic animals. The 'Caspian' species comprise 

 54 per cent in the Kuchurgan inlet and the lower reaches of rivers, and their 



