Although most of the natural coasts in the temperate regions of Japan are composed of rocky reefs along the shore, there have been only a few reports on the relationships between fish communities and rocky reef structures. In this study, researches on relationships between several reef structures and fish communities were conducted based on long-term observations in the shallow sea areas in northern Kyushu, Japan. These survey areas were divided into 4 environmental clusters by using multivariate statistical techniques based on reef structural data. Further, each environmental cluster that provided the intended meaning was retained. In analyzing fish community data, these survey areas were also classified into four clusters (fish community cluster), and we were able to associate each fish community cluster with its corresponding environmental cluster. In addition, several structural factors were positively or negatively correlated with several fish community data. The diversity index of reef structure correlated positively with the diversity index of fishes and the number of fish species; the proportion of rocky bottom areas and the frequency of sea algal correlated positively with the number of individuals. A negative correlation was observed between average depth and the number of immature individuals. These results suggest that diversity of fish communities require reef structures such as a diversity bottom and abundant algal cover. In addition, immature fish require shallow areas for habitation.
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