Lake Hangetsu on the Shiribeshi (Yezo-Fuji) Volcano, Hokkaido

Tanakadate, H.

doi:10.4157/grj.3.9_832

Cited by 2 publications

(2 citation statements)

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“…O-akan (Fig 1). Lake watersheds are isolated from external input by the caldera-wall [35, 36], and the water systems, connected by rivers or underground flow [27, 36, 37], are roughly divided north-south and join at the southern foot of Mt. O-akan, where they then discharge through Akan River, the notch in the south caldera-wall (Fig 1A).…”

Section: Methodsmentioning

confidence: 99%

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Visualization of lake succession as indicated by macrophyte species composition and trophic levels in lakes subdivided by volcanic eruption at Akan Caldera, Hokkaido, Japan

Wakana¹,

Kadono

Urabe

et al. 2021

Preprint

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It is unfeasible to continuously observe ecological succession in lakes because of the long time-scales involved. Thus, the process has been inductively deduced by comparing many lakes with different succession states, or indirectly simulated by tracking studies of smaller water bodies, experiments using microcosms or mesocosms, and reconstruction of lake history by sediment analysis. However, the reality of succession processes in large lakes with slow succession is not well understood, and new approaches are needed. Theoretically, in a group of large and small lakes of similar ages and with similar initial and watershed environments the rate of nutrient accumulation in each lake depends on the ratio of lake size to the watershed area, and the lakes are predicted to evolve to different trophic levels over time. Here, we tested this hypothesis on the 10 lakes of varying sizes in Akan Caldera, Japan, which were formed thousands of years ago by fragmentation due to volcanic eruptions within the caldera. Topographic and water quality studies found that the ratio of lake size (area and volume) to accumulated watershed area, expressed logarithmically, had a positive linear regression with the total phosphorus concentration, an indicator of trophic level. The trophic levels of the lakes were diverse, including oligotrophic, mesotrophic, and eutrophic types in the traditional "lake type" classification based on total phosphorus and chlorophyll-a concentrations. Furthermore, 21 species of aquatic macrophytes were observed by a diving survey, and the species composition was classified into five groups corresponding to the trophic status of the lakes, indicating a conventional "hydrarch succession”. The diversity of water quality and aquatic vegetation in a group of lakes with similar origins paves the way for new comparative studies of lakes, including large lakes.

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Section: Methodsmentioning

confidence: 99%

“…The depth charts of the large lakes, Akan, Panke and Penke, show the remains of valleys on the bottom of the inside caldera wall extending as far as the base of Mt. O-akan [27, 35, 37]. This suggests that the water level of Ko-akanko was extremely low or the basin was exposed by discharge through the notch before the eruption of Mt.…”

Section: Methodsmentioning

confidence: 99%