日本の干潟における絶滅の危機にある動物ベントスの現状と課題

抄録

The present status and problems of threatened benthic animals in the tidal flats of Japan are discussed. These issues came to light during the editing process of “Threatened Animals of Japanese Tidal Flats: Red Data Book (RDB) of Seashore Benthos ” (Japanese Association of Benthology, 2012). In this book, 651 species (462 molluscs, 138 arthropods, 21 polychaetes, and 30 other invertebrates) were designated as threatened benthic animals and categorized as follows; one Extinct, 38 Critically Endangered, 76 Endangered, 168 Vulnerable, 291 Near Threatened, 67 Data Deficient, and 10 Threatened Local Populations. Among various combinations of distributional ranges in Japan, the largest numbers of RDB species were recorded from the area of “Amami Islands and southwards”, i.e. 108 of the 651 species, 15% of the total. The major reasons for RDB listing were habitat degradation and population decline for molluscs, rarity for arthropods, and population decline and habitat degradation for polychaetes. The relatively high percentage of parasitic and symbiotic RDB species (10.4% of molluscs, 18.1% of arthropods, and 14.3% of polychaetes) indicates that the conservation of their host species must also be taken into account. In conclusion, the following actions are recommended: (1) reinforcement of the publishing of Red Lists (RL) and Red Data Books by both national and local governments; (2) expansion of benthic research through various means, including appropriate publicity; (3) compilation of other RL/RDB species besides the invertebrate benthos of tidal flats (e.g., fish or seagrasses of tidal flats, and benthos of rocky shores), and eventual reappraisal of the RDB status of the species covered in Japanese Association of Benthology (2012); and (4) development and appropriate maintenance of specimen collections,and encouragement of popular understanding and governmental support in allocating appropriate human resources and adequate financial resources for the institutions that manage these collections.