Spatial distribution of newly settled and benthic populations of bivalves on tidal flats

Spatial distributions of three bivalve species (Ruditapes philippinarum, Nuttallia olivacea, Musculista senhousia) were examined on the tidal flats. In the present study, different sampling gears were employed for the three benthic phases, i.e. newly settled (less than 0.3mm), juvenile (0.3mm or more but less than 1.0mm) and adult (1.0mm or more) benthic populations. The distributions of the above-mentioned three phases in each species were very similar to each other, so they were found densely at stations around the river mouths. The present study indicates that general features of adult distributions of the three species on each tidal flat are determined during the early settlement stage, whose spatial distributions are probably determined in the stage of planktonic larvae.