沖縄の多様な海底環境が生み出すコケムシの種および生活様式の多様性

抄録

Bryozoans are sessile, clonal animals; about 6,000 living species have been described. The recent study revealed approximately 1,000 species including undescribed species in Japanese waters. Diversity of bryozoans in Okinawa has been not studied in detail; only 22 species have been reported previously. The recent review of bryozoan diversity in the Nansei Islands including Okinawa estimates more than 150 species in this area; the fauna is characterized with both temperate and the Indo-Pacific species. Marine benthic environment in Okinawa varies in the characters, such as dead coral and rubble assemblage in shallow depth, sandy or muddy bottom in deeper area, and mangrove forest at estuarine area. Depends on the diverse benthic environment, bryozoans form colonies of various morphologies on different kinds of substrates such as dead coral and shells. Some bryozoans inhabit muddy bottom by forming erect or free-living colonies. Recent study on bryozoan life-history find the correlation between sand-dwelling bryozoan life-history and climatic characters such as high temperature during summer and disturbance of the water column caused by typhoon. Furthermore, specific relationships between endemic bryozoan species and other organisms in Okinawa also contribute to maintain the high diversity of benthic organisms in Okinawa. Bryozoans are suitable for further study on biogeography and speciation of marine benthic organisms, since some bryozoan species have lower dispersal ability and their distribution is limited in the small area. Taxonomic studies of highly diverse marine organisms in Okinawa have a potential to provide crucial information for development of ecological studies and protection of the organisms and their habitat in Okinawa.