Combined Effects of Temperature and Salinity on the Growth and Pulsation of Moon Jellyfish ( Aurelia coerulea) Ephyrae

Abstract

Blooms of the scyphozoan jellyfish Aurelia coerulea have caused serious problems for the fishing industry and the power plants in the coastal waters of China. The population size of adult medusae is strongly influenced by their ability to survive the ephyra stage. In this study, the growth and pulsation of A. coerulea ephyrae from the northern Yellow Sea were analyzed under sixteen different temperature (10, 15, 20, and 25°C) and salinity (22, 25, 28 and 31 PSU) combinations over a 21-day experimental period. The temperature had a significant effect on the growth of ephyrae. The growth rate of ephyrae increased with increasing temperature. The effects of salinity and its interaction with temperature on the growth of ephyrae were not significant. The highest growth rate was recorded in the 25°C and 25 PSU group. The pulsation rate of ephyrae was also significantly influenced by temperature. The mean pulsation rates of newly released ephyrae were 24.2, 39.1, 52.5, and 73.15 beats min-1 at 10, 15, 20, and 25°C, respectively. As ephyrae developed into medusae, the pulsation rates generally decreased. Salinity and its interaction with temperature did not have a significant effect on the pulsation of ephyrae. We conclude that a warm spring can cause an A. coerulea bloom in that year.