BIVALVE HABITAT BASED ON SEDIMENT-TRANSPORT MECHANICS

Hitoshi Gotoh, Tetsuo Sakai

Abstract


After a storm, thousands of dead bivalves washed upon a beach are sometimes observed. Bivalves are important not only as the marine products but also as the index of the quality of coastal environment. Hence, the field observations of the distribution of bivalves in a coastal zone; and the laboratory experiments on the characteristics of the behavior of bivalves have been performed. An interesting result is found by Yamashita and Matsuoka (1994) in a laboratory experiment on the burrowing process of bivalves under eroding condition due to the oscillatory flow: even when the descending velocity of a sand surface is sufficiently smaller than the burrowing velocity of bivalves, some bivalves cannot stay in the sand layer and are picked-up by oscillatory flow. In this study, the physical background of their results are considered from a viewpoint of sediment transport mechanics. Two important aspects are investigated: the one is the stochastic aspect of the burrowing process of bivalves; and the other is the reverse grading phenomena observed in motion of mixed-size grains.

Keywords


sediment transport; bivalve; bivalve habitat

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