Response of the green alga Ulva prolifera grown at different irradiance levels under ocean acidification at different life cycle stages

• Published in: Botanica Marina
• Main Authors: Ma, Jing, Wang, Wen, Cao, Jun-Yang, Xu, Tian-Peng, Chen, Cheng, Xu, Jun-Tian
• Format: Article in Journal/Newspaper
• Language: English
• Published: Walter de Gruyter GmbH 2022
• Subjects: Ocean acidification
• Online Access: http://dx.doi.org/10.1515/bot-2022-0019; https://www.degruyter.com/document/doi/10.1515/bot-2022-0019/xml; https://www.degruyter.com/document/doi/10.1515/bot-2022-0019/pdf

Abstract The effects of ocean acidification on macroalgae have been extensively studied. However, most studies focused on the adult stages, while other life cycle stages have been overlooked. To better understand the influence of the marine environment on macroalgae, their whole life cycle should be considered, especially the juvenile stage. In this study, Ulva prolifera was cultured under two CO 2 concentrations (400 and 1000 ppmv) and at 10, 18, 30, and 55% of incident sunlight to assess the photosynthetic performance. Our results showed that the acidification treatment had a negative effect on growth at the juvenile stage, but a positive effect at the adult stage. The relative growth rate and effective quantum yield of PSII increased with decreased light levels, irrespective of the CO 2 concentration. At the adult stage, the Chlorophyll (Chl) a , Chl b , and carotenoid contents declined under the high CO 2 concentration. The protein content significantly increased at 18, 30%, and full sunlight levels under the high CO 2 but not under the low CO 2 concentration. Our results suggest that juveniles were less tolerant of the acidic stress compared with the adult stage, although the alga was able to increase cellular proteins in response to the acidic stress.