THE ARAL SEA 



669 



none of the species multiplies there. According to G. Nikolsky, ' the main 

 items of fish diet in this part of the Sea, both in the epilimnion and in the 

 hypolimnion are amphipods {Pontogammarus aralensis). Bivalves and gastro- 

 pod molluscs play a much smaller role. Air insects, mainly caddis fly and 

 chironomids, are of significance in the diet of fish living in the epilimnion 

 (bream, Abramis sapa and vobla in the spring and autumn, and Pelecus and 

 Chalcalburnus throughout the year) ; thus the typical pelagic fish is absent 

 from the Aral Sea and the food which in the Caspian Sea is taken by Clupeo- 

 nella is not used here.' Since there are no small pelagic fish there are no pelagic 

 predators, which are so typical of the Black Sea and to a lesser extent of the 



Cormorants) 



/fSoy 



plankton 



Adacna Smother Chirono 

 Dreissena Molluscs midae 



Phyto- 

 Benthos 



Phryga- 

 nidae 



Vermes 



Fig. 317. Diagram of food correlation of fish in the open parts of the Aral Sea 



(Nikolsky). 1 Pelecus oil tr at us; 2 Abramis sapa; 3 Lucioperca lucioperca; 4 Rutilus 



rutilus; 5 Chalcalburnus chalcoides ; 6 Abramis brama ; 7 Pungitius platygaster. 



Caspian. G. V. Nikolsky notes that the food chain of pike perch turned in 

 the Caspian Sea towards the pelagic forms : plankton — Mysidae — Caspialosa 

 — pike perch ; in the Aral Sea it consists mainly of benthos : plankton — 

 Pontogammarus — Pelecus — pike perch — Abramis sapa. 



According to the nature of their diet the Aral fish can be distinguished into 

 zoobenthophages, planktophages, and predators; phytophages are poorly 

 represented here, and there are no mud-eaters. 



Food correlations of fish of the open parts of the Aral Sea are given in 

 Fig. 317. 



The coastal grouping of Aral Sea fish comprises a large number of species 

 of plant-eaters (rudd and some carp). 



There is only one typical planktophage here, as well as in the open parts of 

 the Sea — stickleback. 



