抄録
The vorticity field was computed by three-dimentional numerical hydrodynamic model applying to Banzu tidal flat waters, in Tokyo Bay, and the juveniles of Short-necked clam were collected from 1984 to 1986. The simulated vorticity distribution was characterized by the large belt with higher magnitude of vorticity stretching in the northem part of the flat, Whereas small patchy regions with high vorticity were found in the southern part of the flat. This may be attributed to the tidal current condition in off-flat region near the tidal flat. In the northern part, tidal current showed relatively higher magnitude, therefore strong current shear can be formed in the interregion between tidal flat and off-flat region.
The significant correlation could be obtained between the distribution of abundance in the larval settlement of short-necked clam and the vorticity field. In addition, the highest abundance of the juveniles less than 20mm in shell length appeared in the proximity of Nakajima, Where the vorticity also showed higher value. It can be suggested that the high vorticity prevents larvae from dispersing to the off-flat water. Our analysis could reveal that the vorticity in the tidal flat area plays an important role on the larval settlement of short-necked clam and distribution of subsequent juvenile.
