Giant jellyfish Nemopilema nomurai gathering in the Yellow Sea-a numerical study

A particle tracking model, based on output from the Princeton Ocean Model (POM), is established to study the year-to-year variation of the gathering of giant jellyfish Nemopilema nomurai in early autumn in the Yellow Sea. Particles standing for scyphistoma adhered to the bottom are put initially along the coast from the Changjiang River estuary to Haizhou Bay. The triggering temperature for scyphistoma strobilation is set to 13 °C. The simulated N. nomurai distribution is in good agreement with observations in August 2009. Model results suggest that more jellyfish gathered near tidal front in August-September of 2008 than during the same period of 2009. Using a set of sensitivity experiments, the influences of temperature and circulation on N. nomurai gathering are discussed. Model results suggest the modeled difference in fall gathering of jellyfish between 2008 and 2009 can be attributed more to changes in circulation than the triggering of strobilation by spring bottom temperature.