The Brown Algae Saccharina japonica and Sargassum horneri Exhibit Species-Specific Responses to Synergistic Stress of Ocean Acidification and Eutrophication

• 作者: LIU Yuxin CAO Jiazhen CHU Yaoyao LIU Yan WANG Qiaohan GONG Qingli LI Jingyu
• 来源期刊: 中国海洋大学学报（自然科学英文版）
• 年，卷（期）: 2021,（5）
• 所属期刊栏目: Life and Fisheries Sciences
• 页码范围: 1253-1262
• 页数: 10页
• 语种: 英文

摘要

Ocean acidification and eutrophication are two important environmental stressors.They inevitably impact marine macroalgae,and hence the coastal ecosystem of China.Saccharina japonica,as the main culture species in China,is suffering the harmful golden tide caused by Sargassum horneri.However,it remains unclear whether the detrimental effects of S.horneri on S.japonica cultivation become more severe in future acidified and eutrophic scenario.In this study,we respectively investigated the effects ofpCO2 (400 μatm and 1000 μatm) and nutrients (non-enriched and enriched seawater) on the growth,photosynthesis,respi-ration,chlorophyll contents,and tissue nitrogen of S.japonica and S.horneri.Results indicated that enrichment of nutrients contrib-uted S.horneri to utilize HCO3.The carbon acquisition pathway shifted from HCO3 to CO2 in S.japonica,while S.horneri re-mained using HCO3 regulated by nutrient enrichment.S.horneri exhibited better photosynthetic traits than S.japonica,with a higher level of net photosynthetic rate and chlorophyll contents at elevated pCO2 and enriched nutrients.Tissue nitrogen also accu-mulated richly in the thalli of S.horneri under higher pCO2 and nutrients.Significant enhancement in growth was only detected in S.horneri under synergistic stress.Together,S.horneri showed competitive dominance in current study.These findings suggest that increasing risk of golden tide in acidified and eutrophic ocean can most likely resuh in great damage to S.japonica cultivation.