Combined effects of ocean acidification and copper exposure on the polyps of moon jellyfish Aurelia coerulea.

Ocean acidification (OA) can interact with Copper (Cu) pollutants and threaten marine organisms and ecosystems. In this study, we assessed the effects of OA and Cu²⁺, alone and in combination, on the polyps of Aurelia coerulea, a common jellyfish renowned for its complex life cycle and frequent global blooms. The results revealed that ocean acidification and Cu²⁺ exposure significantly inhibited the activities of catalase, Ca²⁺-ATPase, acid phosphatase, and alkaline phosphatase in polyps, resulting in antioxidative stress effects and a significant increase in respiratory metabolism. In addition, the combination of ocean acidification and Cu²⁺ exposure caused severe tissue damage to polyps, thereby impeding their predation behavior and reducing their asexual reproduction rates. These two environmental stressors showed synergistic effects on the Ca²⁺-ATPase activity, predation rate, reproduction rate, and injury index of polyps. Therefore, reduced seawater pH and copper contamination adversely affect the physiology, growth, and development of A. coerulea polyps, which may affect the survival and population dynamics of wild populations.