Longterm temporal changes in benthic macro communities on estuary tidal flat detected Rsn method

We have proposed a practical strategy for analyzing faunal data in the form of species×sites using both the Rsn method and the fuzzy cluster analysis. In the present paper this strategy is applied to detect the change of macrobenthic fauna collected from the estuary tidal flat every August during 14 successive years (1982-1996) except 1991. In this tidal flat reclamation work was begun in 1979 for the construction of a port and related facilities. The Rsn ordination together with the fuzzy cluster analysis reveals six communities and four species groups in this macrobenthic fauna. Using the results of the fuzzy clustering of the species groups, the canonical correlation analysis (CCA) is applied between the number of individuals of each species group and the sediment properties. It clearly shows that contrasting temporal changes of the communities are indicated at the stations located to the north and south of the reclaimed land. Significant data, however, can not be derived from the results of the correspondence analysis (CA), because of the presence of outlier sites and species.