Effect of pH, salinity and temperature on the oxygen consumption rate and ammonia excretion rate of Rhopilema esculenta

Rhopilema esculenta is a common jellyfish with high economic value in the coastal areas of China. In order to explore the effects of changes in environmental factors on oxygen consumption rate (OCR) and ammonia excretion rate (AER), this study was conducted through indoor culture to analyze the change characteristics of OCR and AER of juvenile and adult R. esculenta under different pH, salinity and temperature conditions. The results showed that the diameter and dry weight of R. esculenta umbrella can be expressed by W= 0.002 2 e^{0.124 8D} and R²=0.972 4. The changes of the AER and OCR of juvenile and adult R. esculenta were significant affected by pH, salinity and temperature. The AER and OCR of juvenile and adult R. esculenta increased first and then decreased with the increase of pH. Juvenile and adult R. esculenta reached their two max metabolic rates at pH=7 and pH=7.5 respectively, while the frequency of pulsations was the highest. The AER and OCR of juvenile and adult R. esculenta showed a trend of increasing first and then decreasing with the increase in salinity, reaching their maximum when the salinity was 25 and 20 respectively, which had the strongest contraction force when the salinity was 20. The OCR of R. esculenta with different sizes increased with increasing temperature; while AER increased first and then decreased, reaching its maximum at 25 °C. R. esculenta moved and fed at the fastest speed when the temperature was 21 °C, and almost stopped moving when the temperature was lower than 3 °C or higher than 35 °C. The AER Q₁₀ of juvenile R. esculenta was 0.767-4.362, while the OCR Q₁₀ was 1.299-2.201; the AER Q₁₀ of adult R. esculenta was 0.617-4.147, and the OCR Q₁₀ was 0.714-2.519. In this study, the average value of O∶N of R. esculenta under different conditions was 1.392±0.424, indicating that R. esculenta metabolized mainly by consuming protein. This research through the study of the metabolic experiment of R. esculenta under different conditions, explored the effects of different environmental factors on R. esculenta rate of oxygen consumption ammonia excretion rate, to achieve the scientific management of the R. esculenta resources in China and provides the technical support for sustainable development and utilization.