三浦半島江奈湾の底生動物相と希少種の出現状況―東京湾から紀伊半島間にある9ヶ所の干潟との比較

抄録

Survey by the benthos researchers and citizen-based monitoring of intertidal macrozoobenthos was conducted in Ena Bay, southern Miura Peninsula, Kanagawa Prefecture, Japan, from 2013 to 2022. The species richness, including endangered species in Ena Bay, was compared with those for 9 tidal flats from Tokyo Bay to the Kii Peninsula (<500 km spatial scale). Species richness was highest in Ena-Bay (356 taxa), which was characterized by high numbers of mollusks, annelids, and arthropods inhabiting various habitats(reed marshes, seagrass, rocky and boulder zones, and sandy to muddy bottoms). The number of endangered taxa was highest in Tanabe (59 taxa), followed by Ago Bay (50 taxa), Ena Bay (44 taxa), Banzu (40 taxa). Tanabe had 14 indigenous endangered taxa, followed by Ago Bay with 8 taxa, Ena Bay with 6 taxa. Therefore, these tidal flats were considered to precious habitat for conserving Red List macrozoobenthos species. The high macrozoobenthic diversity in Ena Bay was partly due to the high diversities of habitats and environments within a relatively small area at a small spatial scale (<1 km). The macrozoobenthos observed in the southern Miura Peninsula (i.e., Ena, Bishamon, and Koajiro Bays)included many taxa that were nearly extinct in the adjacent Tokyo Bay, a highly urbanized and anthropogenically disturbed bay. The macrozoobenthic communities at the tidal flats in southern Miura Peninsula are a potential source of endangered macrozoobenthos in the metapopulation network in the region.