Mussel habitat in excavated flood-channels in the Ibi River with reference to initial ground heights and elapsed years.

NAGAYAMA Shigeya, HARADA Morihiro, SAGAWA Shiro, KAYABA Yuichi

doi:10.3825/ece.19.131

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揖斐川の高水敷掘削地におけるイシガイ類生息環境―掘削高さおよび経過年数との関係―
イビガワノコウスイシキクッサクチニオケルイシガイルイセイソクカンキョウ : クッサクタカサオヨビケイカネンスウトノカンケイ

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Abstract

This study examined freshwater mussel habitats in excavated flood-channels with reference to initial ground heights and years elapsed since the excavations in the lowland Ibi River in order to facilitate efficient management of inter-levee floodplains using flood- channel excavation work. Mussels were captured in ponds at excavation sites with different ground heights and at different years since the excavations. Time-series data of cumulative sediment depth and the amount of ponds in the sites were also obtained. In the sites with lower excavation heights （but higher than drought water level）, mussel abundance and the proportion of the pond occupied by the mussels were higher, and sediment depths and deposition rates were lower. Mussel abundance and the amount of ponds increased and then decreased with peaks of 5 and 6-9 years after the excavations, respectively, in the context of continuing sedimentation. These results suggest that flood-channel excavations should be strategically implemented so that low excavation sites with 5-9 years elapsed since excavation are always present somewhere in a target river segment.

Journal

Ecology and Civil Engineering

Ecology and Civil Engineering 19 (2), 131-142, 2017

Ecology and Civil Engineering Society

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