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《Resources and Enuironment In The Yangtza Basin》 2001-03
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CHARACTERISTICS AND ECOLOGICAL SIGNIFICANCE OF THE DEVELOPING POPULATION OF BULLACTA EXARATA (PHILIPPI,1848) (MULLUSCA:GASTROPODA,ATYIDAE) IN THE YANGTZE ESTUARY,CHINA

YE Shu-feng,LU Jian-jian(State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200062,China)  
The \$Bullacta exarata\$ population in the Nanhui tidal flat of the south bank of the Yangtze Estuary were examined on May 13~14 and 27~28.The population was clump-distributed,but the contagiousness index was rather low.The density of the population was 21.2 and 32.8 individuals/m\+2 at two sampling dates,respectively,with the corresponding biomass being 25.6 and 44.89 g/m\+2 (wet weight) or 2.05 and 3.49 g/m\+2 (dry weight).The average shell length at two sampling dates was 1.19 and 1.34 cm,respectively.The daily growth of shell height and monthly growth rate were 98.7 μm and 24.9%,respectively.The snails with shell height ranging from 1.00~1.20 cm on May 14 and 1.20~1.40 cm on May 28 were the majotity in the population.Mature adults accounted for 32.4% and 78.3% individuals in the two sampling dates,respectively,indicating that the population was in a trasition period between growth and reproduction phases.The regression relationship between shell height(H) and shell width(B),between H and WW,between the rate and relative rate of water preservation (F1 and F2) and WW was:H=0.180 43+1.275 0*B,WW=0.447 5*H\+\{2.512 8\},F1=0.760 2*WW-0.466 1,F2= 34.021 *WW-8.666,respectively.The average obesity (O) and the percentage of fresh flesh (PF) are 299.27% and 62.15% with the regression equations being O=347.08-38.11*WW and PF=105.74-34.72*WW,respectively.The high population density of \$B.exarata\$ in May 2000 may be related closely with the hydrological conditions and the nutritional materials.The influence of the snail harvest was discussed in relation to the change of the snail population and its role in water purification.
【Fund】: 河口海岸国家重点实验室1999年度开放基金
【CateGory Index】: Q958
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