Sargassum horneri is a foundational species and an important contributor to the floating seaweed stock along the northeastern coast of Asia. In this study, benthic and floating thalli of S . horneri were collected from Changdao Island (37°54′N, 120°43′E), Bohai Bay, China. We conducted an in-situ and an indoor experiment to study the acclimation potential in S . horneri to abiotic conditions at sea surface in autumn and winter. Both benthic and floating thalli were cultured in situ for two months (from October to December) at different depths: 0 m above sea level (masl) and 3 m below sea level (mbsl), and their growth rate, biochemical content, and photosynthetic performance were compared. During the first month of culture, the relative growth rate of floating thalli was 2-fold greater than that of benthic thalli at 0 masl. The photosynthetic rate of most thalli was significantly higher at 0 masl than at 3 mbsl. In the indoor experiments, floating and benthic thalli were exposed to high light intensity (400 μmol photons/(m 2 ·s) photosynthetically active radiation (PAR)) for 21 d, and their photo-acclimation capacities were compared. Under high light intensity, the two types of thalli showed low maximum quantum yield ( F v / F m ) and light utilisation efficiency ( α ) but high light saturation point ( E k ). Floating thalli showed higher photosynthetic rate and photoprotective ability than benthic thalli at high light intensity. The effective quantum yield of photosystem Ⅱ[Y(II)] of both types of thalli recovered after a 6-day treatment with low light intensity (40 μmol photons/(m 2 ·s)). These findings suggest that S . horneri is highly acclimated to the sea surface environment, which possibly contributes to its rapid accumulation and long free-floating periods at the sea surface.

Jingjing LI;Yunlong PANG;Song QIN;Zhengyi LIU;Zhihai ZHONG;Wanlin SONG;Longchuan ZHUANG

Key Laboratory of Marine Hazards Forecasting,Ministry of Natural Resources,Hohai University,Nanjing 210098,China;Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences,Yantai 264003,China;Weihai Vocational College,Weihai 264200,China;Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China

海洋湖沼学报（英文版）

[1]Jingjing LI;Yunlong PANG;Song QIN;Zhengyi LIU;Zhihai ZHONG;Wanlin SONG;Longchuan ZHUANG-.Comparison of the photo-acclimation potential of floating and benthic thalli of Sargassum horneri (Phaeophyta) during autumn and winter)[J].海洋湖沼学报（英文版）,2022(01):195-205

Phaeophyta,Changdao,masl,mbsl

Comparison,acclimation,potential,floating,benthic,thalli,Sargassum,horneri,during,autumn,winter,foundational,species,important,contributor,seaweed,stock,along,northeastern,coast,Asia,In,this,study,were,collected,from,Island,Bohai,Bay,China,We,conducted,situ,indoor,abiotic,conditions,surface,Both,cultured,two,months,October,December,different,depths,above,level,below,their,growth,rate,biochemical,content,performance,compared,During,first,relative,was,fold,greater,than,that,most,significantly,higher,experiments,exposed,light,intensity,photons,photosynthetically,active,radiation,PAR,capacities,Under,types,showed,maximum,quantum,yield,utilisation,efficiency,saturation,point,Floating,photoprotective,ability,effective,photosystem,II,both,recovered,after,day,treatment,These,findings,suggest,highly,acclimated,environment,which,possibly,contributes,its,rapid,accumulation,free,periods

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