東京湾人工潟湖干潟に形成された絶滅危惧種の干潟産腹足類カワアイ Cerithidea djadjariensis(Martin)(軟体動物門,腹足綱)の個体群

概要

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The endangered tidal flat snail, Cerithidea djadjariensis, was considered to extinct locally in Tokyo Bay, central Japan, before 1995. However, our investigation in September 2001 has shown that 16 individuals of this species were found on a muddy tidal flat in artificially constructed Shinhama Lagoon at the innermost part of the Bay, which was constructed in 1977. The size of these individuals ranged between 21.5 mm and 44.7 mm in shell length, and such wide size range suggests the continuous recruitment occurring in several years after the colonization. Spatial distribution of the snail was restricted to a small area (10 m along the shore with 3 m wide) at the edge of reed community, Phragmites australis, although such habitats were widely seen along the lagoon shore. Although origin of the place that planktonic larvae of these individuals came from is unknown, one possible route is the drainage canal about 2 km apart from the lagoon: a population of this species was also present on the tidal flat in the canal before 1990. The present case study suggests that scattering arrange of small habitats is essential to protect endangered tidal flat snails.
日本ベントス学会の論文
2002-06-27