琉球列島の海底洞窟における十脚目甲殻類相と洞内環境との関連について

抄録

This paper provides a review of the past progress and future potential for research on the decapod crustacean fauna in submarine caves of the Ryukyu Islands. Until now, approximately 66 decapod crustacean species (shrimps, lobsters, and anomuran and brachyuran crabs) have been recorded from such caves at six islands in this chain, but recent surveys suggest that up to 100 species may be present. Many of them, however, appear to be accidental intruders or nocturnally emergent species, whereas “cavernicolous” species (animals that have characteristic morphological features such as reduced eyes and/or elongate thoracic limbs and spend their entire adult lives in the caves) are not so common. In addition, recent surveys have shown that the factors determining the distributional pattern of cavernicolous decapods among caves and their ecological partitioning within caves may be influenced by cave morphology and various aspects of the interior environment (light conditions, salinity, substratum, etc.). The urgency of preserving submarine cave environments in the Ryukyu Islands in the face of various threats is emphasized. In particular, 16 species of cavernicolous decapods found in submarine caves are already currently listed in the “Red List of Threatened Marine Species” issued by the Ministry of the Environment, Government of Japan.