Water turbulence effect on egg survival and characteristics of hatched larvae of the Black Sea turbot Scophthalmus maeoticus (Pallas, 1814)

Abstract

The impact of different level of turbulence on developing eggs and prelarvae of the Black Sea turbot Scophthalmus maeoticus obtained from the pair of wild spawners at the end of natural spawning season has been studied. The incubation was carried out at three different levels of turbulence generated by diffused aeration: without aeration (calm water), low aeration (34 ml per minute) and high aeration (75 ml per minute). In calm water hatching rate (HR) of turbot eggs was 20 % and the hatched prelarvae had the longest standard length (SL = 3.13 mm) and the biggest volume of the yolk sac (VYS = 0.37 mm³) as compared to those of low aeration (HR = 18 %; SL = 3.10 mm; VYS = 0.32 mm³) and high aeration conditions (HR = 14 %; SL = 3.10 mm; VYS = 0.29 mm³). One day after hatching the percentage of survived prelarvae from the number of hatched was the highest – 86 % at high aeration, compared with that of low aeration (72 %) and calm water (61 %). Application of turbulence leads to elimination of “poor” quality eggs during incubation, presumably enables hatching of more viable larvae and can reduce mortality of more advanced larvae.