Abstract
It has been clarified that the geophysical environment represented by a suction governs the distribution of a sandy beach amphipod Haustorioides japonicus, which occurs in the intertidal zone of sandy beach. Against this background, in this study, we conducted field studies to investigate whether there is a universal linkage between the distribution of three Haustorioides species, namely Haustorioides japonicus, Haustorioides koreanus, and Haustorioides munsterhjelmi, and the suction, and to clarify the relationship between the distribution of the three Haustorioides species and the variation of suction in association with the tide-induced variation of groundwater level. The distributions of the three Haustorioides species were associated with particular suction, irrespective of the difference in the amphipod species. Namely, the three Haustorioides species became absent where suction exceeded about 2kPa in all beaches, despite more than 10-fold tidal range and its variations.
