Abstract
Cyanea nozakii and Nemopilema nomurai are two major giant jellyfish species frequently blooming in East Asian waters in recent decades. In order to inspect their asexual reproduction performance in climate regimes associated with global warming, variations of podocyst reproduction and strobilation were investigated at five different temperature regimes (approximate simulation of summer in warm years and cold years: temperature increased from 18 to 25A degrees C and then decreased to 18 and 10A degrees C in three months, respectively; approximate simulation of autumn in warm years and cold years: temperature decreased from 18 to 10A degrees C in two and three months, respectively; control: constant 18A degrees C), and three food frequencies (once per 3d, once per 6d, and unfed). Strobilation in C. nozakii occurred at warmer temperature (a parts per thousand yen18A degrees C) but lower temperature (a parts per thousand currency sign18A degrees C) in N. nomurai. More than 90% of ephyrae of C. nozakii and N. nomurai were released in the thermal ranges of 22-25A degrees C and 10-13A degrees C, respectively. Higher percentages of polyps produced podocysts, and increased podocyst production was observed at warmer temperature (> 18A degrees C) and more food supplies in both species. The numbers of ephyrae in C. nozakii and podocysts in N. nomurai were significantly increased by prolonged duration of 18-25A degrees C in summer during warm years. Simultaneously, prolonged duration of 10-18A degrees C significantly increased strobilation percentage, ephyra, and podocyst production in N. nomurai in the autumn. More polyps of N. nomurai strobilating in the autumn proved adverse to outbreaks of medusae in the following summer. The results of this study indicate that the response of asexual reproduction to ocean warming appears species specific. Increased ephyra production in C. nozakii but higher podocyst reproduction in N. nomurai is expected in summer and autumn during warm years.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call