Seaweed farming has been proposed as a strategy for adaptation to ocean acidification, but evidence is largely lacking. Changes of pH and carbon system parameters in surface waters of three seaweed farms along a latitudinal range in China were compared, on the weeks preceding harvesting, with those of the surrounding seawaters. Results confirmed that seaweed farming is efficient in buffering acidification, with Saccharina japonica showing the highest capacity of 0.10 pH increase within the aquaculture area, followed by Gracilariopsis lemaneiformis (ΔpH = 0.04) and Porphyra haitanensis (ΔpH = 0.03). The ranges of pH variability within seaweed farms spanned 0.14-0.30 unit during the monitoring, showing intense fluctuations which may also help marine organisms adapt to enhanced pH temporal variations in the future ocean. Deficit in pCO2 in waters in seaweed farms relative to control waters averaged 58.7 ± 15.9 μatm, ranging from 27.3 to 113.9 μatm across farms. However, ΔpH did not significantly differ between day and night. Dissolved oxygen and Ωarag were also elevated in surface waters at all seaweed farms, which are benefit for the survival of calcifying organisms. Seaweed farming, which unlike natural seaweed forests, is scalable and is not dependent on suitable substrate or light availability, could serve as a low-cost adaptation strategy to ocean acidification and deoxygenation and provide important refugia from ocean acidification.
KAUST Repository Item: Exported on 2021-03-03
Acknowledgements: This study was supported by the National Natural Science Foundation of China (21876148 & 21677122) and Fundamental Research Funds for the Central Universities (2019QNA4051) to X.X., Long-Term Observation and Research Plan in the Changjiang Estuary and the Adjacent East China Sea Project (LORCE, 14282) to J.Z. We thank Mr. Xiaojun Yang and staffs at the Shandong Li'dao Marine Technology Co., Ltd., Mr. Shixiang Ke and staffs at the Zhoushan Risheng Mariculture Co., Ltd., staffs at the Nan'ao coastal laboratory of Shantou University for support in performing on-site measurements and water sample collection, and Dr. Anzhou Cao at Ocean College, Zhejiang University for support in the oceanographical background information of the seaweed farms.
- Environmental Chemistry
- Environmental Engineering
- Waste Management and Disposal