This study aimed to investigate the effects of salinity on the survival and asexual reproduction (budding and strobilation) of the early life stages (planulae, polyps, and ephyrae) of Aurelia coerulea. To this end, short-term salinity tolerance (48h),...
This study aimed to investigate the effects of salinity on the survival and asexual reproduction (budding and strobilation) of the early life stages (planulae, polyps, and ephyrae) of Aurelia coerulea. To this end, short-term salinity tolerance (48h), gradual low-salinity tolerance (6d), and polyp asexual reproduction (90d) were assessed across nine salinity conditions (0-33). In short-term tolerance experiments, planulae exhibited 100% survival at salinities 21 psu≤, with metamorphosis into polyps occurring only at 25 psu≤. Polyps exhibited 100% survival at 17 psu≤, with tentacle morphology and contraction responses maintained stably only at 25≤. Ephyrae survived partially at 17 psu ≤, and survival rates increased with higher salinity. In the gradual low-salinity tolerance experiments, both polyps and ephyrae survived partially up to 5 days at 17 psu. Asexual reproduction of polyps occurred at 29 and 33 psu, with the most active budding and strobilation observed at 33 psu. Experimental results further showed that planulae experienced complete mortality at salinities ≤17 psu, while polyps and ephyrae experienced complete mortality at ≤13 psu, confirming the low limit of salinity. Because osmoregulatory capacity is weak in the early life stages of A. coerulea, decreasing salinity delayed metamorphosis in planulae, shortened polyp tentacles and reduced predatory ability, and suppressed polyp asexual reproduction. Salinity is not only an important factor affecting the survival of the early life stages of A. coerulea, but also a limiting factor regulating active asexual reproduction and the abundance of adult populations. These results provide a basis for explaining the physiological and ecological characteristics of the early life stages of A. coerulea under salinity conditions.