Investigation of different levels of glycerol on cyst hatching percentage, total length and survival of Phallocryptus spinosa and Artemia franciscana

Artemia and fairy shrimps due to propitious size and wide distribution throughout the world, purvey ample feed resources with relatively favorable nutritional value to profitable aquatic species. Ambient water physical-chemical properties affect the biological function of zooplanctonic cysts. Glycerol is an alcoholic compound which is soluble in water and it has three hydroxyl groups that are responsible for solubility in water. There is a relationship between the presence of free glycerol in water and cysts metabolic rate and dormancy duration. The present study aimed to investigate the effects of different levels of free glycerol in the hatchery water on hatching percentage, total length of nauplius and mortality rate of Phallocryptus spinosa and Artemia franciscana cysts. In this experiment, four triplicate treatments including 0% (control), 0.1%, 1% and 10% of glycerol were used on A. franciscana and P. spinosa hatchery water for 48 hours and 72 hours, respectively. The results revealed that 0.1% glycerol was the most efficient level for hatching percentage of P. spinosa cysts with 28.86±1.6%. Also, the size of total length of newly hatched nauplii in this treatment was 0.75±0.08 mm that was significantly greater than the other treatments (P≤0.05); there was no significant difference in the mortality percentage between this treatment and the control treatment. In A. franciscana, the highest hatching rate (68.33±4.71%) and nauplius length (0.90±0.08 mm) were recorded in the 1% glycerol treatment. According to the results, glycerol at 0.1% level for P. spinosa and 1% level for A. franciscana are suitable in the cysts hatching media to increase hatching rate and nauplii performance. Our work could contribute to a better understanding of the hatching biology of dormant life stages in zooplanctonic crustaceans.