Negative effect of sediment penetration resistance on burrowing behavior of the Japanese littleneck clam Ruditapes philippinarum
2009
Nakayama, T.(Hokkaido. Central Fisheries Experiment Station, Yoichi (Japan)) | Fukuda, H. | Hada, Y. | Abe, E. | Sakurai, I.
This study was carried out to examine the negative effect of penetration resistance (PR) of the sediment on burial ability of the Japanese littleneck clam Ruditapes philippinarum. In the laboratory experiment designed to estimate the critical PR for burial ability of the clam, relative burial depth and burrowing rate were compared between following PRs given to the sediment: 0.13, 0.24, 0.41, 0.55, 1.57 and 2.16 MPa. In addition, PRs of the sediment, coupled with other variables such as median grain diameter (dsub(50)), sorting coefficient (sigmasub(1)), mud content and water content, were measured in 12 fishing grounds of the eastern Hokkaido, Japan. No significant correlation was detected between PR and relative burial depth of R. phillipinarum, whereas burrowing rate significantly decreased when PR increased from 0.24 to 0.41 MPa. Multiple regression analysis revealed that PR was best predicted with a combination of 3 variables, depth from the sediment surface (h), dsub(50) and sigmasub(1). These results suggested that burial ability of the clam in bottom disturbance due to erosion and deposition would be lowered when burrowing rate was limited by sand compaction. In conclusion, the combination of h, dsub(50) and sigmasub(1) could be a useful indicator to evaluate the suitability of the sediment for burial ability of R. philippinarum.
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