Highlights
- Combined effects of UVB radiation and increased atmospheric CO2 was assessed on Skeletonema pseudocostatum.
- Additive, synergistic and antagonistic effects were characterized based on modified independent action (IA) model.
- The combined effects on S. pseudocostatum were dose-dependent and target-specific.
- Additivity was most common, synergy occurred in ROS and growth, while carotenoids content reduced antagonistically.
- An effect pathway was developed to characterize the propagation of combined effects across t biological levels.
Abstract
Climate change as a result of increases in greenhouse gas emissions, such as CO2, is causing significant alteration in global environmental conditions, including ocean acidification (OA). Although the depletion of the ozone layer has reduced, the penetration of ultraviolet-B (UVB) radiation into the oceans still remains an environmental factor that may potentially enhance the effects of OA on biota. Improved understanding of the complex interactions between multiple stressors, such as UV-B radiation and increased CO2 levels, is thus important for safeguarding ecosystems and developing effective conservation and management strategies. A 72 h experiment was carried out to investigate the combined effects of UVB irradiance (0.5 W m−2) and varying CO2 levels (350, 500, 1000 ppm) on the diatom Skeletonema pseudocostatum. The study aimed to characterize the potential combined effects at different levels of biological organization, including ROS formation, lipid peroxidation (LPO), photosynthesis, pigments, oxidative phosphorylation (OXPHOS) and growth. The findings indicate that exposure to elevated CO2 (500 ppm) alone resulted in increased total carotenoid content and growth of S. pseudocostatum, but did not significantly impact photosystem efficiency, oxidative stress, and OXPHOS. Sole UVB exposure induced oxidative stress, inhibited photosynthesis and OXPHOS processes, and suppressed growth in S. pseudocostatum. However, when co-exposed with CO2, synergistic impacts were observed for reactive oxygen species (ROS), lipid peroxidation (LPO), and growth, while carotenoids were reduced in an antagonistic manner. A putative impact pathway was proposed as an initial effort to characterize the combined effects of these stressors under proposed future marine OA scenarios involving elevated CO2.
Xie L., Macken A. & Tollefsen K. E., 2025. Interactive effects of elevated atmospheric CO2 and UV-B radiation: a multi-level study on marine diatom Skeletonema pseudocostatum. Ecotoxicology and Environmental Safety 291: 117879. doi: 10.1016/j.ecoenv.2025.117879. Article.
