Thermal fluctuations and CO2 enrichment synergistically accelerate biomass yield of Neopyropia yezoensis

Abstract

Due to the rising atmospheric pCO2, the greenhouse effect in the natural environment has intensified, leading to ocean acidification and frequently extreme temperature events. Limited research has been conducted on the effects of near-shore temperature fluctuations and ocean acidification on macroalgae. In this study, Neopyropia yezoensis (Bangiales, Rhodophyta) was cultured under two CO2 concentrations (LC: 400 μatm and HC: 1000 μatm) and three temperature conditions (10 ℃, 14 ℃, and fluctuation: increased from 10 ℃ to 14 ℃ and then decreased back to 10 ℃ with a fluctuation of 1 ℃ per day). The growth, chlorophyll fluorescence, photosynthetic pigments, and soluble carbohydrate of N. yezoensis were measured. The results showed that the relative growth rate, rETRmax, contents of chlorophyll a, phycoerythrin, and carotenoid in the thalli increased at 14 ℃ and thermal fluctuation, while the content of soluble carbohydrate were inhibited. Moreover, the effect of pCO2 on growth was significant only under temperature fluctuation. Even when the temperature dropped to 10 ℃, the physiological responses of N. yezoensis were still promoted by the thermal fluctuation condition. These findings indicate that the yield and quality of N. yezoensis could potentially improve in the future warming scenarios, and changes observed in N. yezoensis could serve as an early indicator for global climate change.