Морфологічна мінливість бичка кругляка Neogobius melanostomus (Pallas, 1814) у водоймах півдня України за градієнтом солоності

The morphological variability of round goby from freshwater (<0,5 ‰), mesohaline (5 to <18 ‰) and polyhaline (18 to <30 ‰) reservoirs was researched. The results suggest differentiation between samples in groups
“mesohaline”, “freshwater” and “polyhaline” forms. All signs were divided according to the functional activity. The from polihalinnyh reservoirs the most changes have signs, which were measured on the body and the upper fins, while mezohalinnyh – signs on the head and fins. In freshwater groups round goby a general decrease in indexes, in addition to associated with vision and power were noted.