Abstract:In order to understand the interaction between Bullacta exarata and sedimental environment, population of B.exarata and sediment characteristics were investigated at the typical distribution area of the Yellow River estuary in August, 2011. The results were as follows: (1) B. exarata was mainly distributed in mudflats with median particle diameter φ (Mdφ) ranging from 3.73~5.25; and the sediment types were composed of silt, salt-sand and sand-salt. (2) The average organic content and Chl-a concentration in surface sediment of the south intertidal zone was 1.39% and 2.65μg/g, which was significantly higher than in the north of the estuary with an average organic content of 0.54%and Chl-a concentration of 1.48μg/g. (3) The average population density was 16.7ind/m2,which was significantly higher in the south intertidal zone than in the north of the estuary with the average population densities of 0.6ind/m2. The relationship between population density (x) and average shell length (y) could best be expressed as the linear equation:y=-0.180 1x+19.184, R2=0.776．B. exarata body size and population density was inversely proportional; the higher the population density, the smaller the body size. (4) Taylor' power law, Iwao's patch regression and Morisita index analysis results showed that the spatial pattern of B. exarata population in the estuary belonged to the clumped and negative binomial distribution theoretically. (5) There were positive relationships between the density of B. exarata and organic content or Chl-a, suggesting that food source might be one of the main limiting factors for the distribution of B. exarata population.
