| 摘要: |
| 盐度是影响水母生长、繁殖和家庭饲养的重要因素，全球变暖、海水温度上升、极端天气和气候异常已被证明会影响盐度。本研究为探讨叶硝水母（Phyllorhiza chinensis）对盐度的应激响应机制，设置12、22和32共3个盐度梯度，对螅状体、育成体和成体的生长和消化酶活性进行了检测和分析。结果显示人工条件下盐度可引起叶硝水母生活史各阶段生长和消化生理的变化，在3种盐度条件下螅状体均能正常存活和无性繁殖，体内4种消化酶活性均极显著高于育成体和成体（P<0.01），说明螅状体对外界盐度变化表现出较强的适应性，其细胞的渗透调节能力较强，可进一步人工淡水驯化。盐度12有利于育成体和成体的进一步淡化，可作为内陆水族馆和家庭观赏水母用螅状体的保种盐度。盐度22叶硝水母无性繁殖、生长和活力状态较好，4种消化酶活力最高，可作为人工饲养的适宜盐度。各盐度组3个生长阶段胃蛋白酶含量均最高，说明该水母对蛋白质具有较强的消化能力，试验结果为叶硝水母饵料的调整、解析对环境的应激和适应机制及商业养殖开发提供理论依据。 |
| 关键词: 叶硝水母(Phyllorhiza chinensis) 盐度 消化酶 螅状体 水母体 |
| DOI：10.11759/hykx20211116003 |
| 分类号:Q959.132.2 |
| 基金项目:青岛市南区科技发展资金项目（2018-4-011-ZH） |
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| Effects of three levels of salinities on the growth and digestive enzyme activities of Phyllorhiza chinensis at different stages |
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YANG Cui-hua, ZHANG An-qi, JIANG Yu-li, QI Ji-guang
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Qingdao Marine Science and Technology Museum, Qingdao 266003, China
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| Abstract: |
| Salinity is one of the most important factors affecting the growth, reproduction, and family rearing of jellyfish. Phenomena, such as global warming, rising sea temperatures, and extreme weather and climate anomalies such as floods and heatwaves, have been shown to alter absolute salinity values. However, the effect of salinity on the growth and reproduction of jellyfish remains largely unknown. This study aimed to assess whether culture salinity levels affected the growth and digestive enzyme activities of Phyllorhizachinensis. Three salinity levels (12‰, 22‰ and 32‰) were used at three stages (polyp, juvenile, and adult) of cultured jellyfish. Results suggested that salinity affected the growth and digestion of cultured jellyfish. Polyps were capable of growth and asexual reproduction in the three salinity levels. Additionally, polyps had significantly higher digestive enzyme activities (pepsin, cellulase, lipase, and amylase) compared with juveniles and adults (P<0.01). Results showed that appropriate salinity levels improved growth, survival, and digestive enzyme expression under artificial conditions. For example, salinity 12 was beneficial to juvenile and adult breeding and further desalination, and it is suitable for maintaining jellyfish in inland and home aquariums. Salinity 22 also provided the jellyfish with good conditions for asexual reproduction, growth, and vitality. The activities of four digestive enzymes were also highest in this level, suggesting good suitability for artificial breeding. Among the four digestive enzymes, pepsin content was the highest because of the high protein from Artemia nauplii and the high protein demands. Since P. chinensis can degrade protein better than cellulose, dietary fats, and starches, appropriately increasing the ratio of protein in daily bait can reduce the feeding cost. Results also revealed that polyps showed strong adaptability against external salinity changes, and their osmoregulation was stronger than that of juveniles and adults. Further desalination could be used in inland and home aquariums. In the future freshwater aquaculture was possible to improve the economic benefits due to fewer animal diseases, lower feeding costs, more breeders, and so on. Polyps could reproduce asexually to permanently maintain their feeding characteristic in fresh water and can undergo strobilation under a certain condition to produce medusa, which could be fed in freshwater. This study provided a theoretical basis for the adjustment of bait, the activation and adaptation mechanism of P. chinensis to the environment, and its commercial cultivation and development. Our tests detected a certain cellulase in the digestive cavity. However, this requires further study to determine whether P. chinensis has a complete cellulase system or a symbiotic relationship with a fungus or bacteria, such as zooxanthellae, that could produce exogenous cellulose. |
| Key words: Phyllorhiza chinensis salinity digestive enzyme scyphistoma medusa |
