Patterns of Microorganisms Inhabiting Antarctic Freshwater Lakes with Special Reference to Aquatic Moss Pillars

Nakai, Ryosuke; Imura, Satoru; Naganuma, Takeshi

doi:10.1007/978-3-030-02786-5_2

Cited by 4 publications

(4 citation statements)

References 85 publications

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“…The low trophic levels of freshwater lakes in Antarctica are due to the dispersed distribution of habitats because of the extreme weather conditions and the high level of isolation around the continent (Cantonati et al 2020). However, on some Antarctic riverbeds, there are abundant nutrients such as dissolved inorganic nitrogen and phosphate (Tanabe et al 2017), which confirms the existence of rich phytobenthic and endemic communities in some lakes in Antarctica (Toro et al 2007, Nakai et al 2019, Cantonati et al 2020.…”

Section: Limnological Behaviourmentioning

confidence: 82%

The limnology and spectral behaviour of a freshwater lake at Harmony Point, Nelson Island, Antarctica

et al. 2021

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The present study investigates the effect of limnology on the spectral reflectance of a freshwater lake, located in an ice-free area in the Antarctic Peninsula. Field-collected samples generated limnological and spectral parameters. This fact indicates that the studied lake has an ultra-oligotrophic/oligotrophic nature based on chlorophyll a (chl a), which registered concentrations below 3 μg l-1 with no total suspended solids, almost neutral pH and transparency equalled by depth. The water spectral behaviour in each sampling station indicates that the benthic characteristics of the lake have a strong influence as the reflectance at the 705 nm wavelength being greater than that at 583 nm signals the presence of soil and/or vegetation at its bottom. Hence, it is believed that the orbital sensors with spectral bands focused on regions between the green and red edge, such as the MultiSpectral Instrument (MSI) sensor, may present better results for distinguishing the different bottom types found in the research area.

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Section: Limnological Behaviourmentioning

confidence: 82%

The limnology and spectral behaviour of a freshwater lake at Harmony Point, Nelson Island, Antarctica

et al. 2021

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“…The formation of the hollow structure in Koke-Bouzu is positively related to the internal microbiomes (Nakai et al, 2012). The interior of Koke-Bouzu is decomposed and rotten; redox-potential gradients between this rotten interior and the exterior lead to a high diversity of microorganisms that are involved in material cycling in the in situ environment (Nakai et al, 2019). Therefore, we presumed that the hollow structure and its associated microbiomes are related to the large size 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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“…Most of these lakes are oligotrophic, where nutrient concentrations, such as nitrate, nitrite, ammonium, and phosphate, are lower than 0.1 mg l −1 [7]. In the bottom of these lakes, where the water does not freeze throughout the year [8], unique tower-like structures of microbial mats, called moss pillars, have been observed [9,10]. Studies using DNA cloning and sequencing of ribonucleic acid (rRNA) genes revealed the detailed community structure of the moss pillars in Lake Hotoke Ike in Skarvsnes [11,12].…”

Section: Introductionmentioning

confidence: 99%

Investigating Algal Communities in Lacustrine and Hydro-Terrestrial Environments of East Antarctica Using Deep Amplicon Sequencing

et al. 2020

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Antarctica has one of the most extreme environments on Earth, with low temperatures and low nutrient levels. Antarctica’s organisms live primarily in the coastal, ice-free areas which cover approximately 0.18% of the continent’s surface. Members of Cyanobacteria and eukaryotic algae are important primary producers in Antarctica since they can synthesize organic compounds from carbon dioxide and water using solar energy. However, community structures of photosynthetic algae in Antarctica have not yet been fully explored at molecular level. In this study, we collected diverse algal samples in lacustrine and hydro-terrestrial environments of Langhovde and Skarvsnes, which are two ice-free regions in East Antarctica. We performed deep amplicon sequencing of both 16S ribosomal ribonucleic acid (rRNA) and 18S rRNA genes, and we explored the distribution of sequence variants (SVs) of these genes at single nucleotide difference resolution. SVs of filamentous Cyanobacteria genera, including Leptolyngbya, Pseudanabaena, Phormidium, Nodosilinea, Geitlerinama, and Tychonema, were identified in most of the samples, whereas Phormidesmis SVs were distributed in fewer samples. We also detected unicellular, multicellular or heterocyst forming Cyanobacteria strains, but in relatively small abundance. For SVs of eukaryotic algae, Chlorophyta, Cryptophyta, and Ochrophyta were widely distributed among the collected samples. In addition, there was a red colored bloom of eukaryotic alga, Geminigera cryophile (Cryptophyta), in the Langhovde coastal area. Eukaryotic SVs of Acutuncus antarcticus and/or Diphascon pingue of Tardigrada were dominant among most of the samples. Our data revealed the detailed structures of the algal communities in Langhovde and Skarvsnes. This will contribute to our understanding of Antarctic ecosystems and support further research into this subject.

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Patterns of Microorganisms Inhabiting Antarctic Freshwater Lakes with Special Reference to Aquatic Moss Pillars

Cited by 4 publications

References 85 publications

The limnology and spectral behaviour of a freshwater lake at Harmony Point, Nelson Island, Antarctica

The limnology and spectral behaviour of a freshwater lake at Harmony Point, Nelson Island, Antarctica

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

Investigating Algal Communities in Lacustrine and Hydro-Terrestrial Environments of East Antarctica Using Deep Amplicon Sequencing

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