Effect of Silt and Clay on the Settlement of Short-necked Clam Ruditapes philippinarum Larvae

Abstract

In this study, we investigated the effect of silt and clay in the sediment on the settlement of Ruditapes philippinarum larvae. Mountain, river and sea sands of which silt and clay (< 0.075 mm) content was adjusted using silt and clay originating from these sands or dredged sediment (DS) were examined for settlement of R. philippinarum larvae. The addition of DS and Otagawa river sand-originated silt and clay did not accelerate the larval settlement, whereas the mountain and Jigozen sea sands-originated silt and clay promoted larval settlement at 5%. The negative impact of Otagawa river sand-originated silt and clay might be due to its high leachability of Mn, while the accelerated larval settlement by Jigozen sea sands-originated silt and clay could be attributed to its organic contents. The provided results indicate that a suitable ratio of the fine particles to coarse particles exists for the acceleration of the larval settlement, though the effect might be dependent on their chemical properties.