Identification,protection and restoration of spawning habitats are vital for protecting the depleted species.Asian horse-shoe crabs are ecologically important macroinvertebrates in coastal and estuarine ecosystems.However,their spawning habitat stud-ies were limited to several reports in tropical regions,possibly due to the lack of modified survey methods,particularly in habitats with a lower density of spawning adults,and/or intermingled with anthropogenic structures.In this study,the year-round egg distri-bution and spawning habitat baselines of Carcinoscorpius rotundicauda and Tachypleus tridentatus were determined in the northern Beibu Gulf,China.Our findings demonstrated that the peak spawning occurred in June-July and ceased in November-January when the average water temperature dropped below 20℃.Egg aggregations were found＜10cm beneath the sediment surface with regular tidal inundation,regardless of seasonal changes,in the vicinity of natural and artificial structures with elevated,mildly sloping sub-stratum within the high tide zones.The nests were characterized by medium-sized sediment grains(0.5-0.9 mm),high temperatures(31-34℃),low water contents(0.8％-0.9％),and total organic carbon contents(0.5％-0.7％),which might maximize the hatching success.The identified nesting beaches were close to nursery habitats for juveniles,and tidal creeks were present as the possible cor-ridor connecting these two important habitats through the dominant mangrove forests.The findings provide valuable insights in the scope of spawning behavior and nest-site selection of Asian horseshoe crabs under a mixture of natural and artificial structures,which could benefit future management efforts for the exploited spawning populations.

KWAN Kit Yue;FU Yijian;ZHONG Mufeng;KUANG Yang;BAI Haiwei;ZHANG Ce;ZHEN Wenquan;XU Peng;WANG Chun-Chieh;ZHU Junhua

College of Marine Sciences,Beibu Gulf Ocean Development Research Center,Beibu Gulf University,Qinzhou 535011,China;Guangxi Key Laboratory of Beibu Gulf Marine Biodiversity Conservation,Qinzhou 535011,China;Guangxi Key Laboratory of Marine Disaster in the Beibu Gulf,Qinzhou 535011,China;Guangxi Beibu Gulf Marine Research Center,Guangxi Academy of Sciences,Nanning 530007,China

中国海洋大学学报（自然科学英文版）

[1]KWAN Kit Yue;FU Yijian;ZHONG Mufeng;KUANG Yang;BAI Haiwei;ZHANG Ce;ZHEN Wenquan;XU Peng;WANG Chun-Chieh;ZHU Junhua-.Spatiotemporal Distribution of Asian Horseshoe Crab Eggs Are Highly Intermingled with Anthropogenic Structures in Northern Beibu Gulf,China)[J].中国海洋大学学报（自然科学英文版）,2022(03):531-540

Horseshoe,Intermingled,macroinvertebrates,intermingled,Carcinoscorpius,rotundicauda,ridor

Spatiotemporal,Distribution,Asian,Crab,Eggs,Are,Highly,Anthropogenic,Structures,Northern,Beibu,Gulf,China,Identification,protection,restoration,spawning,habitats,are,vital,protecting,depleted,species,crabs,ecologically,important,coastal,estuarine,ecosystems,However,their,were,limited,several,reports,tropical,regions,possibly,due,lack,modified,survey,methods,particularly,lower,density,adults,anthropogenic,structures,this,study,year,round,egg,distri,baselines,Tachypleus,tridentatus,determined,northern,Our,findings,demonstrated,that,peak,occurred,June,July,ceased,November,January,when,average,water,dropped,below,aggregations,found,10cm,beneath,sediment,surface,regular,tidal,inundation,regardless,seasonal,changes,vicinity,natural,artificial,elevated,mildly,sloping,sub,stratum,within,high,tide,zones,nests,characterized,by,medium,sized,grains,temperatures,contents,total,organic,carbon,which,might,maximize,hatching,success,identified,nesting,beaches,close,nursery,juveniles,creeks,present,possible,connecting,these,two,through,dominant,mangrove,forests,provide,valuable,insights,scope,behavior,site,selection,horseshoe,under,mixture,could,benefit,future,management,efforts,exploited,populations

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