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 of pCO_(2)(400μatm and 1000μatm)and nutrients(non-enriched and enriched seawater)on the growth,photosynthesis,respiration,chlorophyll contents,and tissue nitrogen of S.japonica and S.horneri.Results indicated that enrichment of nutrients contributed S.horneri to utilize HCO_(3)^(−).The carbon acquisition pathway shifted from HCO_(3)^(−)to CO_(2) in S.japonica,while S.horneri re-mained using HCO_(3)^(−)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 pCO_(2) and enriched nutrients.Tissue nitrogen also accumulated richly in the thalli of S.horneri under higher pCO_(2) 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 result in great damage to S.japonica cultivation.
基金
This work is funded by the Major Scientific and Technological Innovation Project of Shandong Provincial Key Research and Development Program(No.2019JZZY020708).
