| The Yangtze Estuary wetland is one of the biggest estuary in China.It also provides an important habitat area for the different stage of Eriocheir sinensis,such as zoea larva,megalopa,juvenile crab,matured crab.When E.sinensis developed at the stage of reproductive phase,it propagates amount of zoea larva at the brackish water;after the zoea larva development after the metamorphosis stage,megalopa was formed;tidal transported megalopa to the beach along the estuary,and then the tail of crab was collected at the development stage of juvenile;at last,the juvenile would migrate upstream.In recent years,as the economic quickly developed,the natural resources of E.sinensis was fully captured.A lot of projects were constructed along the estuary,for example,the reclaim project in the estuary marshes,irrigation and drainage system,culvert of rivers and lakes,reservoir,airports,deep channel,et al.Both vast economic benefits and social value were created through those projects.However,there were many negative effects on the estuary ecosystem because of those projects.Habitat was destroyed,biodiversity was decreased,water environment changed,spawning ground become weakened year by year.Especially,the E.sinensis habitat area was destroyed as time goes on.The current study aimed at restorying the habitat area along the migration routes of ecological corridor,we hope the current study can provide reference data on the resource conservation and the E.sinensis resources utilization.(1)The study was based on the behavior and physiological of juvenile in different intensity of illumination environment.The current study showed that the juvenile E.sinensis has the light avoidance behavior accompanying with the circadian rhythms.The number of pigment distributing in the monocular in light adaption was much more than that in dark adaption through electron microscopy.The diameter of rhabdom,Perirhabdomal vacuoles,multivesicular bodies,rough endoplasmic reticulum was significant different between two environment conditions.The result of the juvenile crab transcriptome in light adaption showed that:42,700,296 raw reads and the original sequence of bases is 6,697,575,706;after removal low quality sequence,we get trim reads of 35,625,234,after removal of low quality sequences accounted for the proportion of the original sequence was 83.43%.In the dark adaption,we get 44,354,806 raw reads,and the original sequence of bases is 6,447,744,696;after removal low quality sequence,we get trim reads of 37,418,712,and removal of low quality sequences accounted for the proportion of the original sequence was 84.36%.The result of GO analysis of Unigene showed that:the Unigene was expressed 84%(14,027)in the cell binding among the molecular function category;37%(7,407)and 22%(3,901)Unigene were each expressed in cell component and membrane enclosed lumen;29%(14,775)and 28%(13,978)expressed in the cellular process and metabolic process.The all-Unigene of juvenile E.sinensis in light and dark adaptation can be divided into 25 categories.The function of COG in Unigene involved most of the life activities.There are 21,113 function gene were existed;there are 28 Unigene related with nuclear structure;and other kinds of gene expression abundance keep different level.(2)Both the behavior selection and standard metabolism of juvenile E.sinensis in different salinity area were tested in this study.the result showed that the most adaptived salinity for juvenile E.sinensis ranged from 0 to 20 psu.The most adaptive salinity that juvenile E.sinensis lived ranged from salinity 0 psu to 12 psu,with percentage of distribution were 25.3%and 30.0%;there was least percentage in the salinity sector is 20 psu with 2.4%average percentage.The results showed that the physiological metabolic activity was affected by dissolved oxygen and salinity.Fat is the main function material at high dissolved oxygen stage;the fat and carbohydrates provide energy at low dissolved oxygen stage,the protein act as energy substances and its proportion of energy supplying increased.This current study was used to accumulate the information in the early stages of development of E.sinensis.(3)The artificial floating wetland(AFW)were constructed outside of Qingcaosha Reservoir along the Yangtze Estuary.Juvenile E.sinensis was detected monthly in the AFW,the AFW provided habitat for juvenile crab.In the process of investigated phage,the time that the juvenile grew ranged from Mary to september.The regression analysis between the carapace length and weight of E.sinensis,one regression equation was concluded:y =0.0132e3.4557x(R2=0.924).(4)The temperature,transparency,dissolved oxygen and conductivity around the AFW were dinvested in this paper.The transparency around the AFW was significant higher than that of the external water environment.The current study also indicated that the Yangtze Estuary belong to heavy metal polluted area.The results showed that Cu,Zn,Pb,Cr is the heavy metal pollution in the Yangtze Estuary.Four heavy metals were enriched in the reed on the AFW,the distribution of heavy metals in different tissues existed obviously different.(5)The stability,development and maturity of the AFW ecosystem was used to evaluate the health of the ecosystem.The total energy consumption of the AFW ecosystem showed the highest value in autumn(810.601 t/km2),the total consumption energy about the AFW ecosystem showed the lowest value in winter(384.452 t/km2),this value in other two seasons showed the middle value.The primary productivity of the ecosystem(TPP)and total output(TEX)was increased gradually;and the two values nearly equaled with each other in the same season.The respiratory system(TR)indicated the different values in all seasons.The total respiration showed the highest value in autumn and the lowest value in spring;the value of total primary production/total respiration(TPP/TR)indicated in spring(29.797),the lowest value was detected in winter(651.913);the connection index(CI)in spring was the highest(0.233),the CI value of AFW in other seasons(summer,autumn and winter)were 0.190,0.185 and 0.175.Ecological system omnivory index(SOI)in spring kept the highest value(0.188)and the value of other season was below this value.The connection index(CI)and system omnivory index(SOI)in different seasons was differrent(0.233,0.190,0.185,and 0.175)and(0.188,0.050,0.088,0.065).The ecological system function group connection index(CI)and spring showed the highest value.The AFW ecosystem has the highest degree of aggregation in spring,the other seasons showed less value than other seasons,and the stability of the ecosystem in spring is higher than other seasons.This AFW ecosystem belong to low development,low mature and highly stable stage. |
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