Effects of Temperature and Salinity on Egg Hatching of a Planktonic Shrimp Acetes intermedius Omori, 1975

Abstract

The effects of temperature and salinity on the egg hatching of the planktonic shrimp Acetes intermedius were studied. Four temperatures, 15, 20, 25 and 30°C, and eight salinities ranging from 0 to 35 at 5 ppt increments were employed to form the different combinations. Eggs failed to hatch at 15°C at all salinities examined and at salinity 0 to 10 ppt at all temperatures examined. Hatching success begins to decrease at salinities 15 ppt at 30°C and at salinity 20 ppt at both 25°C and 20°C. When salinity is not lower than salinity 25 ppt, the hatching success reaches nearly 90% on the average and is generally similar among temperatures tested. Hatching started at about 10, 14, and 29h after spawning at the incubation temperature of 30, 25, 20°C, respectively. Hatching time is the shortest at salinity 25 ppt at both 25 and 30°C, whereas it is similar among salinities at 20°C. The results suggest that the spawning ground of A. intermedius is likely located within the estuary where the salinity ranges from 25 to 30 ppt and the hatching time may vary seasonally in the southwestern coast of Taiwan.