Abstract:

Currently, artificially bred Chrysaora quinquecirrha primarily rely on hatched Artemia sp. (1 day old) as food under laboratory conditions, which, in comparison to their natural habitat, limits their dietary diversity. To better replicate their wild living environment and enrich the nutritional diet of the jellyfish polyp colony, polyps of Chrysaora quinquecirrha were cultivated in 1L glass beakers under controlled temperature settings[(23±1)℃], and fed with larvae of Artemia sp., Brachionus plicatilis, and Aurelia coerulea, respectively. To explore the long-term preservation techniques for Chrysaora quinquecirrha polyps in the laboratory, four feeding frequencies were established for each group: once daily, once every three days, once every seven days, and once every fifteen days. The results revealed that the polyps thrived in all three live feed groups, with a complete survival rate in the Brachionus plicatilis group, whereas some mortality was noted in the Aurelia coerulea group. Different feeding frequencies exerted varying impacts on the growth indices of Chrysaora quinquecirrha polyps. The maximum polyp count was observed at a feeding frequency of once daily (31.0±1.0). Furthermore, the highest podocyst production also occurred at a frequency of once daily (336.0±15.5). Notably, the highest podocyst germination rate was found in the Artemia sp. and Brachionus plicatilis groups at a frequency of once every fifteen days (37.5±0.8)%. The percentage of budding reproduction of Aurelia coerulea group at a feeding frequency of once daily accounted for the highest proportion of the total asexual reproduction of the two types, reaching 24.0%, which was significantly different from the other feed groups. Lastly, all groups fed with Artemia sp., Brachionus plicatilis, and Aurelia coerulea at the fifteen-day frequency showed a relatively lower number of ephyra released from transverse cleavage compared to the other groups. This study investigated the effects of diverse fresh foods and feeding frequencies on the asexual reproduction and development of Chrysaora quinquecirrha polyps under long-term laboratory conditions to reduce the risk of germplasm degradation, offering valuable insights to the artificial preservation of jellyfish and the enhancement of population density.

Key words: Chrysaora quinquecirrha, polyp, fresh food, feeding frequency, asexual reproduction