Орнитофауна закарпатской низменности в зимний период

Abstract

The construction of the cascade of reservoirs in the middle and low Dnieper and decrease of the river discharge change the hydrological regime of the low Dnieper and the Dnieper-Bug estuary: the floods are rare now, flow speed falls, the estuary becomes salty. Sea species of fish, which were not observed previously, appeared now: Odontogadus merlarzgus euxinus, Mugil saliens, Crenilabrus occelatus; the number of salt water fishes - Clupeonella delicatula delicatula, Atherina mochon pontica, Gobiidae — increased. Atherina mochon pontica penetrated into the Dnieper and began to propagate now, that was not observed previously. The rheophilic species — Chondrostonia nasus natio boristhe-nicum, Leuciscus leuciscus, Gobio gobio, Abrainis ballerus and Abrarnis sapa disappeared from the ichthyofauna of the low Dnieper. Such species as Leuciscus cephalus, Aspius aspius, Leuciscus idus are oppressed; Palecus cultratus lost its industrial value. Propagation of the Acipenser guldenstadti colchicus and Alosa vissleri pontica is impeded and of small effect. The isolation of the low Dnieper and the Dnieper-Bug estuary from the sea is proposed by means of dam construction in Ochakov region.