抄録
The relationship between distribution of juvenile japanese littleneck Ruditapes phillippinarum and physical
environment, especially bottom condition and water current, was investigated in west Mikawa-bay. Sediment
samples were collected by Smith-McIntyre grab. These samples were sieved with lmm mesh screen and bivalves
were picked up and measured shell length. The oxydised layer and the reduced layer of substratum were observed
throughout the transparent corer, and then upper 10 cm of cored sediments were used for particle size analysis.
The water current-of the bay was analyzed by the three dimensional hydrodynamic model. The juveniles always
distributed more abundantly in the mouth of Yahagi river than in other stations. The thickness of oxidized layer
in bottom sediment was more than 20 cm in the river mouth, whereas most of other station showed less than 10 cm.
The landward water current in bottom and lower strata of the river was observed according to the numerical analysis.
Thus, it was considered that the bottom condition and the water movement contributed to the survival of
juveniles and the entrainment of planktonic larvae to the habitat, respectively.
