海洋酸化和低氧及其节律性变化对海蜇碟状幼体的影响

人类生产活动引起的全球气候变化加剧作为重要的环境问题,海洋中pCO₂和溶解氧的失衡及富营养化加剧了许多沿海生态系统的酸化和低氧现象。海蜇(Rhopilema esculentum)为我国重要的渔业资源之一,具有食用价值及潜在药用价值。本研究评估了海蜇碟状幼体在海洋酸化和低氧及其昼夜节律变化胁迫下的生理响应:碟状幼体暴露于两个pH水平(酸化pH 7.6,正常pH 8.1)和两个溶解氧水平(低氧2mg·L^–1,常氧7mg·L^–1)维持7d,胁迫因素维持恒定或昼夜节律性变化,测定其伞部直径、收缩频率及酸碱平衡、免疫和抗氧化相关酶活力。研究表明,海洋酸化和低氧在不同程度上影响海蜇碟状幼体的生理代谢和生长发育,且酸化和低氧之间表现出部分拮抗作用,昼夜波动的暴露模式对海蜇碟状幼体的损伤程度大于恒定的暴露模式。

Effects of diurnal changes of ocean acidification and hypoxia on the ephyrae of Rhopilema esculentum

The anthropogenic aggravation of global climate change is an important environmental problem, and the imbalance between pCO₂ and dissolved oxygen in the ocean and eutrophication have aggravated the acidification and hypoxia of many coastal ecosystems. Rhopilema esculentum is one of the most important fishery resources in China, which has edible value and potential medicinal value. In this study, the physiological responses of the ephyrae of R. esculentum under the stress of ocean acidification and hypoxia and their circadian rhythm changes were evaluated: the ephyrae was exposed to two levels of pH (acidified pH 7.6; normal pH 8.1) and two dissolved oxygen (DO) levels (hypoxia 2 mg·L^-1; normoxic 7 mg·L^-1) for 7 days. The stress factors remained constant or fluctuating, and the bell diameter, pulsation rates and activities of acid-base balance, immunity and antioxidation related enzymes of ephyrae were measured. The results showed that the ocean acidification and hypoxia affected the physiological metabolism, growth and development of R. esculentum ephyrae in different degrees, and there was a partial antagonism between acidification and hypoxia. The effects of diurnal fluctuating exposure mode to R. esculentum ephyrae was more harmful than that of constant exposure mode.