Projection of Wind Waves Which Induce Rotary Motion of Marimo in Lake Akan

Sano, Fumiya; Nakayama, Keisuke; Yamada, Toshiro; Sato, Yukinobu; Maruya, Yasuyuki; Komai, Katsuaki; Oyama, Yoichi; Wakana, Isamu

doi:10.2208/jscejoe.72.i_988

Cited by 6 publications

(6 citation statements)

References 4 publications

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“…It was shown that the wind-driven current washes giant Marimo from a colony to shore in the typhoon event, but does not occur on regular days 19 . In contrast, the oscillation due to wind waves is the dominant motion for Marimo on regular days 25 . They revealed that the fetch at Churui Bay is the longest, 2.5 km when the wind direction is from southeast to southwest, the prevailing wind direction in Lake Akan 24 .…”

Section: Rotation Of Marimomentioning

confidence: 93%

“…In 2014, the Japan broadcasting corporation took the first underwater footage of the rotation of Marimo in Lake Akan. By analyzing these video images and the accompanying meteorological data, our research team was able to verify that wind waves rotate Marimo 14,25 . In the six years since those experiments were conducted, further advances have been made in measurement technologies, and the new systems have the potential to provide additional data to unravel the age-old mystery of how Marimo grow and maintain their sizeable spherical shape.…”

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confidence: 99%

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The structure and formation of giant Marimo (Aegagropila linnaei) in Lake Akan, Japan

Nakayama

Komai

Ogata

et al. 2021

Sci Rep

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Aegagropila linnaei is a freshwater green alga, which at one time was distributed widely in the northern hemisphere. The aggregate often forms beautiful spherical shapes known as “lake balls” or “Marimo”. The population of Marimo has been rapidly decreasing worldwide, and today the large Marimo, with a diameter of more than 12 cm, exit only in Lake Akan in Japan. However, how Marimo grow and maintain their unique spherical shape in natural habitats remains unsolved. Here we show that Marimo are “polished” into spheres by the rotation induced by wind waves. Such a process enhances the water exchange between the interior and exterior of the Marimo, thereby recycling nutrients for growth. Our results provide an intriguing model of a physical environment interacting with biological processes in a self-sustaining ecosystem. We also demonstrate that Marimo have a spherical annual ring structure, and their growth rate is associated with ice cover. The balance between the ecology of Marimo and the water environment in Lake Akan is highly vulnerable and at risk of irreversible degradation. We must endeavor to rescue Marimo from the fate of a "canary in the coal mine" of global climate change.

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Section: Rotation Of Marimomentioning

confidence: 93%

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confidence: 99%

The structure and formation of giant Marimo (Aegagropila linnaei) in Lake Akan, Japan

Nakayama

Komai

Ogata

et al. 2021

Sci Rep

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“…Physical factors in the growing environment are involved in the developmental mechanism of the ball-like marimo. Wind waves are a driving force which rotates marimo and maintains their rounded spherical form (Sano et al, 2016). The rotation of marimo enables photosynthesis over the entire marimo surface and removes sediment from the surface.…”

Section: The Development Process and The Life Cycles Of The Radial-type Marimomentioning

confidence: 99%

“…The internal multi-layers support the massive growth of the radial-type marimo It is known that external factors such as light, water quality, and water motion are involved in giving the marimo its spherical shape (Boedeker et al, 2010a;Sano et al, 2016). In addition to environmental conditions, we considered that various internal factors might be crucial for the more massive growth of the radial-type marimo.…”

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confidence: 99%

Internal microbial zonation during the massive growth of marimo, a lake ball of Aegagropila linnaei in Lake Akan

Nakai

Wakana²,

Niki

2021

iScience

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“…It is known that external factors such as light, water quality, and water motion are involved in giving the marimo its spherical shape (Boedeker et al, 2010a; SANO et al, 2016). In addition to environmental conditions, we considered that various internal factors might be crucial for the more massive growth of the radial-type marimo.…”

Section: Introductionmentioning

confidence: 99%

Internal microbial zonation assists in the massive growth of marimo, a lake ball ofAegagropila linnaeiin Lake Akan

Nakai

Wakana²,

Niki

2021

Preprint

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Marimo (lake ball) is an uncommon ball-like aggregation of the green alga, Aegagropila linnaei1. Although A. linnaei is broadly distributed in fresh and brackish waters in the northern hemisphere, marimo colonies are found only in particular habitats. The colonies have been gradually shrinking in recent years. Nevertheless, it is not clear how and why A. linnaei forms such massive spherical aggregations. Here, we report the bacterial microbiomes inside various sizes and aggregating structures of natural marimo collected from Lake Akan, Japan. We observed multi-layers composed of sediment particles only in the sizeable radial-type marimo with a >20 cm diameter, not in the tangled-type marimo. The deeper layers were enriched by Nitrospira, potential novel sulphur-oxidizing bacteria, and sulphate-reducing Desulfobacteraceae bacteria. The sulphur cycle-related bacteria are unique to Lake Akan due to sulphur deposits from the nearby volcanic mountains. Some of them were also recovered from lake sediments. Microorganisms of the multi-layers would form biofilms incorporating nearby sediment, which would function as microbial seals within large radial-type marimo. We propose that the layer structure provides habitats for diverse bacterial communities, promotes airtightness of the marimo, and finally contributes to the massive growth of the aggregation. These findings provide a clue to deciphering the massive growth of endangered marimo aggregates.

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Projection of Wind Waves Which Induce Rotary Motion of Marimo in Lake Akan

Cited by 6 publications

References 4 publications

The structure and formation of giant Marimo (Aegagropila linnaei) in Lake Akan, Japan

The structure and formation of giant Marimo (Aegagropila linnaei) in Lake Akan, Japan

Internal microbial zonation during the massive growth of marimo, a lake ball of Aegagropila linnaei in Lake Akan

Internal microbial zonation assists in the massive growth of marimo, a lake ball ofAegagropila linnaeiin Lake Akan

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