Abstract
The sessile organism community structure at nine sites on the intertidal coast of Tokyo Bay (excluding the bay-mouth region) was investigated seasonally from July 2004 to May 2005 with semi-quantitative measurements of each species. Cluster analysis conducted according to the dissimilarity of community structure classified the study sites into Clusters X and Y. Cluster Y was further divided into two subgroups, Clusters Y1 and Y2. Cluster X consisted of four sites in the northwestern part of the bay, while Cluster Y1 was composed of two sites in Chiba City and Cluster Y2 was made up of three sites relatively close to the mouth of the bay. Nine species, including the Pacific oyster Crassostrea gigas, the native barnacle Fistulobalanus albicostatus, and the introduced mussel Xenostrobus securis, distinguished Cluster X. Six species, including the green alga Ulva sp., the sea anemone Haliplanella lineata, and the serpulid polychaete Hydroides ezoensis, represented Cluster Y1, and six species, including the red alga Caulacanthus ustulatus, the chiton Acanthochitona achates, and the limpet Lottia tenuisculpta, characterized Cluster Y2. We suggest that the characteristic species of Cluster X indicate low salinity and high eutrophication, while those of Cluster Y2 indicate relatively higher salinity and lower eutrophication.
