The abnormal increase of drifting brown alga Sargassum horneri was initially documented in 2007.It formed blooms along the coast of East China Sea and Yellow Sea in 2017.In this study,we investigated the changes of sp...The abnormal increase of drifting brown alga Sargassum horneri was initially documented in 2007.It formed blooms along the coast of East China Sea and Yellow Sea in 2017.In this study,we investigated the changes of specific growth rate and resource accumulation of drifting S.horneri in response to temperature and nitrogen richness at different growth stages under laboratory condition.The investigation lasted from June 2015 to April 2016 with the observation made every two months.The results showed that the life cycle consists of a few growth stages dividable with morphological characteristics.The growth can be divided into shedding and withering(August),rapid growing(October to September),slow growing(February),rapid growing(April)and maturation(June)stages.Under the experimental condition,algal segments were found to grow at temperatures ranging from 5 to 25℃in 12 days even when nitrogen is deficient.A significant difference in the special growth rate(SGR)between nitrogen-enriched and nitrogen-removed treatments was found in most months(P<0.05).SGR was lower in August and February than that in other months.Nitrogen and chlorophyll contents in algal segments were different among different temperatures,nitrogen supply and seasons.Nitrogen content was higher in February and April than that in other months in both nitrogen-enriched and nitrogen-removed treatments.The results showed that the demand of S.horneri for nitrogen increased in spring when it grows fast.It is likely that the high temperature and nitrogen concentration in winter and spring lead to the high biomass accumulation of drifting S.horneri.展开更多
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 Chi...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.展开更多
Environmental changes,such as ocean acidification and eutrophication,have created threats to kelp mariculture.In this study,the growth,photosynthesis,respiration and nutrient composition of Saccharina japonica were ev...Environmental changes,such as ocean acidification and eutrophication,have created threats to kelp mariculture.In this study,the growth,photosynthesis,respiration and nutrient composition of Saccharina japonica were evaluated at different levels of pCO2(400 and 800μL L−1)and nutrients(nutrient-enriched and non-enriched seawater).Elevated pCO2 decreased the relative growth rate(RGR),net photosynthetic rate and contents of tissue carbon and tissue nitrogen under non-enriched nutrient conditions,but it had no significant effect on these parameters under nutrient-enriched conditions.The dark respiration rate was positively affected by elevated pCO2 regardless of the nutrient conditions.However,the C:N was unaffected by elevated pCO2 at both nutrient levels.These results implied that ocean acidification could reduce the production and nutrient contents in the tissues of S.japonica,which was associated with nutrient conditions.展开更多
基金supported by the Public Science and Technology Research Funds of Ocean from State Oceanic Administration, People’s Republic of China (Nos. 200905 0202, 201405040-4)
文摘The abnormal increase of drifting brown alga Sargassum horneri was initially documented in 2007.It formed blooms along the coast of East China Sea and Yellow Sea in 2017.In this study,we investigated the changes of specific growth rate and resource accumulation of drifting S.horneri in response to temperature and nitrogen richness at different growth stages under laboratory condition.The investigation lasted from June 2015 to April 2016 with the observation made every two months.The results showed that the life cycle consists of a few growth stages dividable with morphological characteristics.The growth can be divided into shedding and withering(August),rapid growing(October to September),slow growing(February),rapid growing(April)and maturation(June)stages.Under the experimental condition,algal segments were found to grow at temperatures ranging from 5 to 25℃in 12 days even when nitrogen is deficient.A significant difference in the special growth rate(SGR)between nitrogen-enriched and nitrogen-removed treatments was found in most months(P<0.05).SGR was lower in August and February than that in other months.Nitrogen and chlorophyll contents in algal segments were different among different temperatures,nitrogen supply and seasons.Nitrogen content was higher in February and April than that in other months in both nitrogen-enriched and nitrogen-removed treatments.The results showed that the demand of S.horneri for nitrogen increased in spring when it grows fast.It is likely that the high temperature and nitrogen concentration in winter and spring lead to the high biomass accumulation of drifting S.horneri.
基金This work is funded by the Major Scientific and Technological Innovation Project of Shandong Provincial Key Research and Development Program(No.2019JZZY020708).
文摘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Ocean University of China in 2018 and the Major Scientific and Technological Innovation Project of Shandong Provincial Key Research and Development Program(No.2019JZZY020708).
文摘Environmental changes,such as ocean acidification and eutrophication,have created threats to kelp mariculture.In this study,the growth,photosynthesis,respiration and nutrient composition of Saccharina japonica were evaluated at different levels of pCO2(400 and 800μL L−1)and nutrients(nutrient-enriched and non-enriched seawater).Elevated pCO2 decreased the relative growth rate(RGR),net photosynthetic rate and contents of tissue carbon and tissue nitrogen under non-enriched nutrient conditions,but it had no significant effect on these parameters under nutrient-enriched conditions.The dark respiration rate was positively affected by elevated pCO2 regardless of the nutrient conditions.However,the C:N was unaffected by elevated pCO2 at both nutrient levels.These results implied that ocean acidification could reduce the production and nutrient contents in the tissues of S.japonica,which was associated with nutrient conditions.
