A generalized method for assessing inter-levee floodplain pond environments focused on unionid mussels.

Nagayama, Shigeya; Kato, Yasumitsu; Miyawaki, Shigenari; Harada, Masayasu; Kayaba, Yuichi

doi:10.3825/ece.21.135

Cited by 1 publication

(1 citation statement)

References 17 publications

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“…Freshwater unionid mussels (Unionidae) are globally threatened and in need of conservation (Ferreira-Rodríguez et al 2019). They can also serve as ideal target species for conservation in freshwater ecosystems (Geist 2010) and are representative species of floodplain-dependent organisms in Japanese lowland rivers (Nagayama et al 2019). Pond-like floodplain water bodies (FWBs) with high connectivity to the main river channels (high inundation frequency) are vital habitats for mussels in Japanese lowland rivers (Negishi et al 2012b).…”

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confidence: 99%

Habitat aging and degradation in terrestrialized floodplains: a need to rejuvenate processes for sustaining freshwater mussel populations

Nagayama,

Harada,

Negishi

et al. 2023

Restoration Ecology

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Progressive floodplain terrestrialization leads to the deterioration of floodplain ecosystems. Although the importance of hydrological connectivity between floodplain habitats and river channels for floodplain‐dependent organisms has been emphasized, less attention has been paid to the temporal relationship between habitat degradation and aquatic organisms. In this study, we examined temporal changes in mussel population structures and the hydrological connectivity of pond‐like floodplain water bodies (FWBs) in the terrestrialized floodplains of a lowland river in Japan. We tested the hypothesis that FWB habitats for mussels degrade over time, while newly formed FWBs contribute to providing recruitment sites for mussels. The habitat age for 53 FWBs was determined as of 2018, using historical aerial photographs. Inundation frequency, mussel abundance, and size structures (shell length) were also investigated in the FWBs in 2007 and 2018. Mussel abundance decreased with FWB aging (6–36 years), which coincided with a decrease in inundation frequency. In most existing FWBs, mussel abundance in all size classes decreased over the decade (2007–2018). In contrast, small individuals occurred in the newly formed FWBs at age 6, and in the existing FWBs where inundation frequency slightly increased over the decade (2007–2018), such FWBs were rare. In conclusion, the “young” and “rejuvenated” FWBs were found to be critically important for the recruitment and persistence of mussel populations. This suggests that the floodplain management strategy of “cyclic floodplain rejuvenation” could be applicable for mussel conservation in terrestrialized floodplains of lowland rivers.

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