Spatial And Temporal Patterns Of Larval Attachment,Recruitment,Survival,and Growth Of Suminoe Oyster(Crassostrea Ariakensis) And Kumamoto Oyster(Crassostrea Sikamea)

The vertical pattern of attachment,complement,survival and growth of oyster larvae is of great significance to the planning of oyster reef restoration.In the coastal intertidal zone of China,there is a vertical zonation pattern in which Crassostrea ariakensis and Crassostrea sikamea coexisted,and the attachment and recruitment patterns of larvae of the two species were quite different.This paper discussed two kinds of oyster larvae of vertical distribution pattern in growth and survival,near the river in two dimensions of time and space analysis oysters and C.sikamea larvae attached preference,analysis the oyster larvae adhesion after survival and growth pattern of juvenile oyster,examine the different attachment base on the time of oysters to complement and influence of survival,These will provide reference for future oyster reef restoration strategy.The following three experiments were carried out:1.Vertical spatial pattern of survival rate and growth rate of larvae of Crassostrea ariakensis and Crassostrea sikamea after attachmentThe survival patterns of the larvae and larvae of C.ariakensis and C.sikamea were investigated.In late August 2021,the attachment experiment of two kinds of oyster was carried out at Shanghai Luchao Harbor.The results showed that the abundance of juvenile attachment decreased with the increase of elevation,and the number of oysters in low tide area was as follows:C.ariakensis>C.sikamea;The number of oysters in high tide area was as follows:C.sikamea>C.ariakensis,and the abundance of oyster larva attachment was significantly different at different heights and among different species(P<0.01).The kumamoto oyster can adapt to attaching to the high tide zone.The survival rate and growth rate of oyster larvae at different altitudes were studied in Jiantiaogang Beach of Sanmen County,Zhejiang Province.The vertical spatial pattern of survival rate and growth rate of oyster larvae was investigated.It was found that the survival rate of oyster larvae in C.ariakensis was lower than that in C.sikamea.The survival rate of young oysters was higher in low tide area than in high tide area.There was a significant difference in survival rate between the two species of oyster(F=214.322,P<0.01),and in different space(Elevation:F=8.419,P<0.01;Orientation:F=9.677,P<0.01)showed extremely significant change.There were significant differences between species and orientation(F=8.333,P<0.01)and elevation(F=4.692,P<0.01).The young oysters of C.ariakensis adapted to the growth and life in low tide area,while the young oysters of C.sikamea had strong adaptability in all tide areas.In terms of survival rate and growth rate,C.sikamea is more dominant.The experiment was conducted twice a month at the altitude of 0.6 m and 1.6 m in Lijiangtan oyster reef.The attachment and replenishment experiment of oyster larvae began in early June and ended in late September,and the replenishment amount showed significant temporal and spatial variation(Time:F=52.651,P<0.001;Space:F=12.448;P<0.001),the two replenishment peaks of oyster appeared in mid-late July and early September respectively.Oyster reef of Lijiangtan was abundant in oyster recruitment,and C.sikamea had a high recruitment in the whole reef area.More oysters were added in the low tide area,but less in the high reef area.Three experiments showed that the larvae of C.sikamea were distributed in all tidal zones,while C.ariakensis was only distributed in the middle and lower tidal zones.In the juvenile stage,the growth and survival of C.sikamea is more advantageous.The best replenishment period for oysters is from late July to early September.2.Spatial and temporal patterns of two oyster species in oyster reef of Jiantiaogang River Beach,Sanmen County,Zhejiang ProvinceIn this study,the species,genetic diversity,resource density and replenishment potential of oysters in oyster reef of oyster bank in Jiantiaogang,Sanmen County,Zhejiang Province were investigated,the spatial and temporal patterns of oyster resources and larval recruitment were tested,and the ecological status and restrictive factors of oyster bank natural oyster reef were evaluated.There are six species of oyster in Lijiangtan oyster reef which are C.ariakensis,C.sikamea,Crassostrea angulata and Crassostrea hongkongensis,Talonostrea talonata and Crassostrea gigas.In the composition of oyster community,the percentages of C.sikamea,C.hongkongensis and C.ariakensis were 92.92%,5.00%and 2.08%,respectively,and the numbers of the other three species were only found in qualitative samples.The average total density of oysters in spring and autumn was 97±40 ind./m~2 and 1770±467 ind./m~2 respectively.In general,the density of C.sikamea decreased gradually,while that of C.ariakensis and C.hongkongensis,increased gradually with the decreasing elevation gradient.At the same time,large number of oysters were added to the intertidal zone in summer.The results showed that there was an obvious zonal pattern between oyster oysters and oyster oysters,and oyster reef maintained a healthy and sustainable oyster community.However,overfishing,sediment deposition and alien species invasion were the main restricting factors of oyster reef in oyster beach,while biological and abiotic factors limited the growth of C.sikamea in low tide area.3.Effects of attachment base placement time on juvenile recruitment and growth of oysterThis study investigated the recruitment and growth of oysters on the adherent base at different placement times,studied the spatial and temporal patterns of oyster recruitment at different placement periods,determined the optimal timing and elevation of oyster reef placement,and discussed the abiotic and biological stress of oyster growth process.The highest oyster abundance was found on the attachment base on August 5th at 2.1m elevation(35±9 ind./225 cm~2),and the highest total oyster abundance was found in early August.The abundance of oyster on the adherent base was the lowest(2±1ind./225 cm~2)on September 16th at 2.1m elevation.There was a significant difference between different elevation and oyster abundance(F=7.952,P<0.001),and there was a significant difference between different placement periods of attachment and oyster abundance(F=39.006,P<0.001).The maximum shell of oyster was 91mm higher than that of adhesion base on May 25 at an elevation of 0.1m,and the minimum shell was3mm higher than that of adhesion base on May 25th at an elevation of 1.1 m.Different placement periods of attachment groups had significant effects on shell height(F=4.078,P<0.001),and different elevation of attachment groups had significant effects on shell height(F=28.136,P<0.001).The results showed that the best time and place to release the adherent was in the high tide area from July to August,and in the low tide area in May,considering the supply of C.ariakensis.