Relation between tide and phytopigment, suspended solid concentration of Manila clam, Ruditapes philippinarum, farming ground.
Phytopigment and suspended solid concentrations in bottom sea water with tidal rhythm at estuary of a Manila clam, Ruditapes philippinarum [Tapes philippinarum], farming ground were investigated. Chlorophyll a in the bottom sea water increased at flood and high tide, and decreased at ebb and low tide. Chlorophyll a in the sediment flux increased from flood to high tide, and decreased from ebb to low tide. Fine particles in the sediment flux had a high ratio of chlorophyll a and phytopigments. These results suggest that phytoplankton and sediment are supplied mainly from offshore to the estuary with the tide during flood to high tide periods. Phytopigment contents in the digestive diverticula of Manila clams increased rapidly from flood to high tide. These results indicate that algal diet of Manila clam may be supplied mostly during the flood to high tide period. Manila clam actively digest algal diets during these periods.