Physical factors affecting the survival of Tachypleus tridentatus eggs were investigated by translocating their eggs between the high intertidal zone and the low intertidal zone of a known spawning site.The mean egg survival rates per day were highest in the mid intertidal zone(45.1％±25.4％)and the lowest in the low intertidal zone(13.3％±27.6％).Differences in the elevation,air expo-sure time,and water content of the spawning ground were significant factors determining the egg survival rates.Excessive or insuffi-cient air exposure time resulted in inadequate water content at higher and lower intertidal zones and could reduce egg survival.On the other hand,moderate saturation and dehydration were repeated with each tidal movement in the mid intertidal zone.This dynamic is considered as one of the crucial factors for the survival of eggs and is considered optimal for spawning.Therefore,the protection of the mid intertidal zone is imperative for maximizing the egg survival rate in Tsuyazaki Cove where almost all suitable nesting sites have disappeared due to coastal development.By protecting these optimal sites for spawning and recovering other optimal sites on suitable beaches,a positive contribution can be made to future management and conservation.The study also suggests that translocating eggs from marginal to optimal spawning sites might be a recovery strategy for this globally endangered species.

Environmental Fluid Dynamics Laboratory,Department of Urban and Environmental Engineering,Graduate School of Engineering,Kyushu University,Fukuoka 819-0395,Japan;Tsuyazaki Seaside Nature School,Fukutsu 811-3304,Japan;Fishery Research Laboratory,Department of Bioresource Science,Graduate School of Bioenvironmental Science,Kyushu University,Fukuoka 819-0395,Japan

[1]ITAYA Shinji;SHUUNO Mari;ONIKURA Norio;TAI Akira;YANO Shinichiro-.Effect of Intertidal Elevation at Tsuyazaki Cove,Fukuoka,Japan on Survival Rate of Horseshoe Crab Tachypleus tridentatus Eggs)[J].中国海洋大学学报（自然科学英文版）,2022(03):601-610

Intertidal,Tsuyazaki,Cove,Fukuoka,Horseshoe,translocating

Effect,Elevation,Japan,Survival,Rate,Crab,Tachypleus,tridentatus,Eggs,Physical,factors,affecting,survival,eggs,were,investigated,by,their,between,intertidal,known,spawning,mean,rates,day,highest,mid,lowest,Differences,elevation,air,water,content,ground,significant,determining,Excessive,insuffi,cient,exposure,resulted,inadequate,higher,lower,zones,could,reduce,On,other,hand,moderate,saturation,dehydration,repeated,movement,This,dynamic,considered,crucial,optimal,Therefore,protection,imperative,maximizing,where,almost,suitable,nesting,sites,have,disappeared,due,coastal,development,By,protecting,these,recovering,beaches,positive,contribution,made,future,management,conservation,study,also,suggests,that,from,marginal,might,recovery,strategy,this,globally,endangered,species

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