An Ecological Study on the Distribution of Intertidal Sessile Animals in Inner Tokyo Bay

Abstract

Vertical and horizontal distribution of sessile animals on intertidal substrata in eutrophicated inner Tokyo Bay was observed. Sessile animal assemblage at most of the observation sites consisted mainly of two species. The barnacle Chthamalus challengeri made a belt in the upper and middle intertidal levels, and the mussel Mytilus edulis galloprovincialis made another in the lower level.In some estuarine sites, the lower part of the Chthamalus belt was replaced by another barnacle Balanus amphitrite, and the upper part of the Mytilus belt by another mussel Limnoperna fortunei kikuchii. This suggests that salinity condition is an important factor on the horizontal faunal change, and competition for space may influence the vertical distribution of the intertidal sessile animals.