To what extent has Ayu (&lt;i&gt;Plecoglossus altivelis&lt;/i&gt;)'s spawning environment been clarified?

FUJITA, Tomohiko; YOKOYAMA, Ryota; Kato, Yasumitsu; Ito, Osamu; Harada, Masayasu

doi:10.3825/ece.21-00021

Cited by 4 publications

(1 citation statement)

References 10 publications

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“…Thus, we focussed on three fish species with different life cycles and habitats in the Tedori River: Ayu is a vital freshwater fish species in Japan, prized not only as a food source but also for its economic value and popularity among anglers. (Fujita et al, 2022). In this study, we examined data from the Ishikawa Prefectural Water Surface Experiment Station's Ayu spawning surveys, which reported the number of Ayu eggs found in their spawning sites along the Tedori River between 2007 and 2020…”

Section: Effects On Fish and Their Habitatsmentioning

confidence: 99%

Impacts of sediment transported downstream from the 2015 deep‐seated landslide in Mt. Hakusan, Japan

Thapa,

Daimaru,

Ichion

et al. 2024

Earth Surf Processes Landf

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A massive landslide occurred in May 2015 in the Mt. Hakusan Sennindani area, leading to the discharge of a substantial amount of sediment into the Tedori River. We conducted a cross‐sectional analysis of secondary data to assess the potential effects of discharged sediments on the downstream environment, including long‐term turbidity in rivers, alterations in fish habitats, and groundwater depletion. To analyse the spatio‐temporal changes in the river floodplain elevation and paddy fields, aerial photographs and airborne light detection and ranging data were assessed using the ArcGIS software. After the landslide, the turbidity of the Tedori River increased and continued flowing turbid for approximately 6 months. Turbid water spread in the alluvial fan through the irrigation canal network and sediment was deposited in the paddy fields, leading to a reduction in infiltration rates. The groundwater level in the alluvial fan area decreased by more than 2.0 m following the 2015 Sennindani landslide. The sediment deposition in the river floodplain increased by 0.58 m from 2013 to 2015 (pre‐ and post‐landslide). The sediment from upstream destroyed the spawning sites of the Ayu fish along the Tedori River, leading to a decrease in the number of eggs laid in 2015 and 2016 to the lowest levels. The Tomiyo fish disappeared in 2016 and 2017, downstream of the alluvial fan, which received water recharge from the Tedori River. Moreover, Chum salmon showed an exceptionally high anadromous movement towards the Tedori River from coastal areas during 2015 and 2016. In conclusion, discharged sediment from deep upstream landslides can have various adverse impacts on downstream ecosystems, and recovery to their original state may require a considerable amount of time.

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Section: Effects On Fish and Their Habitatsmentioning

confidence: 99%