Photosynthesis, pigments and ultrastructure of the alpine snow alga<i>Chlamydomonas nivalis</i>

Remias, Daniel; Lütz‐Meindl, Ursula; Lütz, Cornelius

doi:10.1080/09670260500202148

Cited by 228 publications

(202 citation statements)

References 38 publications

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“…1) demonstrated previous observations [16][17][18][19][20][21][22][23][24] that the appearance of red snow coincides with increased melt rate and temporal trends in melt predictors (Fig. 1a).…”

supporting

confidence: 72%

“…Thus, snow algae increase liquid water availability through 'bioalbedo' 18 , determined by the absorptive properties of their photosynthetic and secondary pigments. The chlorophylls and carotenoids in red-snow algae-particularly the heat-dissipating tetraterpenoid astaxanthin that colours cells red as protection from excess radiation 23,24 -reduce snow-surface albedo in the visible spectrum. Nutrient depletion in the snowpack triggers production of carotenoids 20 in non-motile cells that ultimately overwinter as buried cysts.…”

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confidence: 99%

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The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

et al. 2017

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A lack of liquid water limits life on glaciers worldwide but specialized microbes still colonize these environments. These microbes reduce surface albedo, which, in turn, could lead to warming and enhanced glacier melt. Here we present results from a replicated, controlled field experiment to quantify the impact of microbes on snowmelt in red-snow communities. Addition of nitrogen-phosphorous-potassium fertilizer increased alga cell counts nearly fourfold, to levels similar to nitrogen-phosphorusenriched lakes; water alone increased counts by half. The manipulated alga abundance explained a third of the observed variability in snowmelt. Using a normalized-di erence spectral index we estimated alga abundance from satellite imagery and calculated microbial contribution to snowmelt on an icefield of 1,900 km 2 . The red-snow area extended over about 700 km 2 , and in this area we determined that microbial communities were responsible for 17% of the total snowmelt there. Our results support hypotheses that snow-dwelling microbes increase glacier melt directly in a bio-geophysical feedback by lowering albedo and indirectly by exposing low-albedo glacier ice. Radiative forcing due to perennial populations of microbes may match that of non-living particulates at high latitudes. Their contribution to climate warming is likely to grow with increased melt and nutrient input.G lacier ablation is sensitive to changes in albedo 1 , with atmospheric 2,3 , hydrological 4 and ecological 5,6 consequences. Fresh snow reflects >90% of visible radiation, but during melt its grain size and water content increase, reducing albedo and further increasing snowmelt 1 . Impurities, including black carbon 3 , dust 4 , and resident microbes [7][8][9][10][11][12][13][14][15][16][17][18][19] , also lower albedo; however, microbes differ from non-living particulates in several critical ways. Perennial populations of photosynthetic microbes actively resurface following overwinter burial by snow 20 , and depend on liquid water and nutrients for survival and reproduction 13,14,[20][21][22] . This requirement for liquid water in a frozen environment imposes a selective force favouring a physiology that increases melt proximal to cell walls. The generation of meltwater through microbes' albedoreducing properties motivates an hypothesis of bio-geophysical feedback on glacial landscapes 13,16 , such as the Greenland ice sheet. This feedback hypothesis, whereby microbes increase because they produce needed meltwater, is an active research area [13][14][15][16][17][18][19] , yet field experiments testing its assumptions are absent.Glacier microbiomes are water-limited 21,22 , because ice is generally not metabolically available, and oligotrophic, because their nutrient content equals that of precipitation plus deposition by airborne dust, pollen, and so on, with only limited N-fixation by local cyanobacteria 21,22 . Moreover, rapidly percolating water through large-grained snow may exacerbate both water-and nutrient limitation for algae in supraglacial...

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confidence: 72%

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confidence: 99%

The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

et al. 2017

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“…The average spherical zygote of Chlamydomonas nivalis is 14.9 mm in diameter (Remias et al 2005), whereas the propagating unit (encasement of up to 16 zygotes in a mucilaginous envelope) of Coenochloris sp. may be up to 60 mm in diameter (Fott 1974).…”

Section: Brown Et Al-snow Algae Are Communities Of Clonesmentioning

confidence: 99%

A Community of Clones: Snow Algae Are Diverse Communities of Spatially Structured Clones

Brown

Ungerer

Jumpponen

2016

International Journal of Plant Sciences

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Premise of research. Snow algae are cosmopolitan and often colonize late-season snowpacks. These snow algae do not occur in isolation; rather, visible algal blooms consist of multispecies communities. Although several of these common snow algae have been characterized taxonomically, their inter-and intraspecific diversity remains unknown. Further, the phylogeographic and biogeographic structuring of snow algal species is poorly understood.Methodology. Algal communities were censused by sequencing the variable internal transcribed spacer 2 locus using Illumina MiSeq. We further analyzed two of the most common and abundant algal operational taxonomic units (OTUs) for biogeographic haplotype diversity.Pivotal results. Our data show that the communities are diverse and taxonomically broad (orders: Chlamydomonadales [74% of OTUs], Microthamniales [20% OTUs], and Chlorellales [6% OTUs]). We demonstrate that the two most common species (best nucleotide basic local alignment search tool match to Coenochloris sp. and Chlamydomonas sp.) have distinct haplotype distributions locally and regionally. Each sampled algal colony was dominated by one and only one haplotype, with negligible intraspecific haplotype diversity.Conclusions. Our results suggest that snow algae are communities of clones within a discrete patch yet are heterogeneous across the landscape. Thus, these communities are likely structured via strong priority effects, intense kin competition, and dispersal limitations.

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“…High performance liquid chromatography (HPLC) analysis of all plastid pigments and α-tocopherol were essentially performed as described in Remias et al (2005). The pigments were calculated on the basis of total Chla=1.…”

Section: Pigment Determinationmentioning

confidence: 99%

Physiological, biochemical, and ultrastructural responses of the green macroalga Urospora penicilliformis from Arctic Spitsbergen to UV radiation

2009

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Exposure of the filamentous turf green alga Urospora penicilliformis to ambient and artificial ultraviolet radiation (UVR) revealed a considerable resilient species. This explains the ability of this alga to thrive in the middleupper intertidal zones of the Arctic sea where it is periodically exposed to environmental extremes. A transient UVR effect on photosynthesis under photosynthetically active radiation (PAR) + UV-A and PAR + UV-A + UV-B was found, but dynamic recovery of photoinhibition was observed immediately after reduction of the photon fluence rate of PAR in the absence or presence of background UVR under laboratory and natural solar radiation, respectively. Chlorophylls, carotenoids, and xanthophyll cycle pigments (violaxanthin, antheraxanthin, and zeaxanthin) concentrations were not significantly different between freshly collected samples and filaments exposed to additional laboratory radiation treatment. The ultrastructure of the U. penicilliformis gametophytes showed that the cells are well adapted to UVR. No significant ultrastructural alterations were observed in filaments exposed to different spectral irradiance in the laboratory compared to in situ acclimated specimen. The antioxidant α-tocopherol was detected in minute quantity while the search for flavonoid-like compounds was negative. Other UV screening strategies or certain genetically fixed physiological protective mechanism could be operating in this species responsible for their occurrence in higher shoreline and ecological success. Further molecular and biochemical studies are needed to elucidate the stress resistance in this turf alga. There is an indication that the extremely thick cell wall of U. penicilliformis gametophytes covered with mucilage sheath and dense layer of mineral depositions may provide a shield against unfavorable environmental conditions in general and against UVR in particular.

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Photosynthesis, pigments and ultrastructure of the alpine snow algaChlamydomonas nivalis

Cited by 228 publications

References 38 publications

The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

A Community of Clones: Snow Algae Are Diverse Communities of Spatially Structured Clones

Physiological, biochemical, and ultrastructural responses of the green macroalga Urospora penicilliformis from Arctic Spitsbergen to UV radiation

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