The 2019/2020 summer of Antarctic heatwaves

Robinson, Sharon A.; Klekociuk, Andrew; King, Diana H.; Rojas, M.; Zúñiga, Gustavo E.; Bergstrom, Dana M.

doi:10.1111/gcb.15083

Cited by 77 publications

(76 citation statements)

References 14 publications

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“…If historic distribution of spore-dispersed organisms such as Ceratodon has been structured by atmospheric circulation, then climate change and ozone depletion, which are changing the position and strength of such wind belts (e.g. Polvani et al, 2011 ; Thompson et al, 2011 ; Turner et al, 2014 ; Robinson and Erickson, 2015 ; Robinson et al, 2020 ), will likely influence dispersal in the future. Increased ice melt is also predicted to increasingly open up new areas for colonization especially in polar and montane regions (e.g.…”

Section: Discussionmentioning

confidence: 99%

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Latitudinal Biogeographic Structuring in the Globally Distributed Moss Ceratodon purpureus

et al. 2020

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Biogeographic patterns of globally widespread species are expected to reflect regional structure, as well as connectivity caused by occasional long-distance dispersal. We assessed the level and drivers of population structure, connectivity, and timescales of population isolation in one of the most widespread and ruderal plants in the world — the common moss Ceratodon purpureus . We applied phylogenetic, population genetic, and molecular dating analyses to a global (n = 147) sampling data set, using three chloroplast loci and one nuclear locus. The plastid data revealed several distinct and geographically structured lineages, with connectivity patterns associated with worldwide, latitudinal “bands.” These imply that connectivity is strongly influenced by global atmospheric circulation patterns, with dispersal and establishment beyond these latitudinal bands less common. Biogeographic patterns were less clear within the nuclear marker, with gene duplication likely hindering the detection of these. Divergence time analyses indicated that the current matrilineal population structure in C. purpureus has developed over the past six million years, with lineages diverging during the late Miocene, Pliocene, and Quaternary. Several colonization events in the Antarctic were apparent, as well as one old and distinct Antarctic clade, possibly isolated on the continent since the Pliocene. As C. purpureus is considered a model organism, the matrilineal biogeographic structure identified here provides a useful framework for future genetic and developmental studies on bryophytes. Our general findings may also be relevant to understanding global environmental influences on the biogeography of other organisms with microscopic propagules (e.g., spores) dispersed by wind.

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Section: Discussionmentioning

confidence: 99%

“…Increased ice melt is also predicted to increasingly open up new areas for colonization especially in polar and montane regions (e.g. Lee et al, 2017 ; Robinson et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

Latitudinal Biogeographic Structuring in the Globally Distributed Moss Ceratodon purpureus

et al. 2020

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“…The AP experienced significant warming in the last several decades of the 20 th century, with the hottest day on record (18.4°C) recently recorded at Esperanza Station on 2020-02-06 in the AP region (Robinson et al, 2020). The warming trend and persistently warmer conditions in the AP could be resulting in more snow-algae growth in coastal areas, which in turn could have a positive feedback on surface albedo and melting.…”

Section: Future Outlookmentioning

confidence: 97%

Spectral Characterization, Radiative Forcing, and Pigment Content of Coastal Antarctic Snow Algae: Approaches to Spectrally Discriminate Red and Green Communities and Their Impact on Snowmelt

Khan¹,

Dierssen²,

Scambos³

et al. 2020

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Abstract. Here, we present radiative forcing (RF) estimates by snow algae in the Antarctic Peninsula (AP) region from multi-year measurements of solar radiation and ground-based hyperspectral characterization of red and green snow algae collected during a brief field expedition in austral summer 2018. Our analysis includes pigment content from samples at three bloom sites. Algal biomass in the snow and albedo reduction are well-correlated across the visible spectrum. Relative to clean snow, visibly green-patches reduce snow albedo by ~ 40 % and red-patches by ~ 20 %. However, red communities absorb considerably more light per mg of pigment compared to green communities, particularly in green wavelengths. Based on our study results, it should be possible to differentiate red and green algae using Sentinel-2 bands in blue, green and red wavelengths. Instantaneous RF averages were double for green (180 W m−2) vs. red communities (88 W m−2), with a maximum of 228 W m−2. Based on multi-year solar radiation measurements at Palmer Station, this translated to a mean daily RF of ~ 26 W m−2 (green) and ~ 13 W m−2 (red) during peak growing season – on par with mid-latitude dust attributions capable of advancing snowmelt. This results in ~ 2522 m3 of snow melted by green-colored-algae and ~ 1218 m3 of snow melted by red-colored-algae annually over the summer, suggesting snow algae play a significant role in snowmelt in the AP regions where they occur. We suggest impacts of RF by snow algae on snowmelt be accounted for in future estimates of Antarctic ice-free expansion in the AP region.

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“…Even so, the percentage of time at which the temperature of mosses allows a positive net CO 2 assimilation must be enough to compensate for loss of carbon by respiration in order to achieve the very low growth rates (average 1.33 mm per year) reported for these Antarctic mosses (Clarke et al, 2012). In future, under climate change, Antarctic mosses are also expected to experience an increase in air temperatures and this would be expected to lead to an increase in the percentage of time they spend at optimal temperatures (Robinson et al, 2020). Our current estimation of carbon balance suggests that carbon balance can only be positive if a large reduction of carbon loss by respiration is assumed for the lowest temperatures (Figure 3).…”

Section: A B D Cmentioning

confidence: 99%

It Is Hot in the Sun: Antarctic Mosses Have High Temperature Optima for Photosynthesis Despite Cold Climate

et al. 2020

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The terrestrial flora of Antarctica's frozen continent is restricted to sparse ice-free areas and dominated by lichens and bryophytes. These plants frequently battle sub-zero temperatures, extreme winds and reduced water availability; all influencing their ability to survive and grow. Antarctic mosses, however, can have canopy temperatures well above air temperature. At midday, canopy temperatures can exceed 15°C, depending on moss turf water content. In this study, the optimum temperature of photosynthesis was determined for six Antarctic moss species: Bryum pseudotriquetrum, Ceratodon purpureus, Chorisodontium aciphyllum, Polytrichastrum alpinum, Sanionia uncinata, and Schistidium antarctici collected from King George Island (maritime Antarctica) and/ or the Windmill Islands, East Antarctica. Both chlorophyll fluorescence and gas exchange showed maximum values of electron transport rate occurred at canopy temperatures higher than 20°C. The optimum temperature for both net assimilation of CO 2 and photoprotective heat dissipation of three East Antarctic species was 20-30°C and at temperatures below 10°C, mesophyll conductance did not significantly differ from 0. Maximum mitochondrial respiration rates occurred at temperatures higher than 35°C and were lower by around 80% at 5°C. Despite the extreme cold conditions that Antarctic mosses face over winter, the photosynthetic apparatus appears optimised to warm temperatures. Our estimation of the total carbon balance suggests that survival in this cold environment may rely on a capacity to maximize photosynthesis for brief periods during summer and minimize respiratory carbon losses in cold conditions.

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The 2019/2020 summer of Antarctic heatwaves

Cited by 77 publications

References 14 publications

Latitudinal Biogeographic Structuring in the Globally Distributed Moss Ceratodon purpureus

Latitudinal Biogeographic Structuring in the Globally Distributed Moss Ceratodon purpureus

Spectral Characterization, Radiative Forcing, and Pigment Content of Coastal Antarctic Snow Algae: Approaches to Spectrally Discriminate Red and Green Communities and Their Impact on Snowmelt

It Is Hot in the Sun: Antarctic Mosses Have High Temperature Optima for Photosynthesis Despite Cold Climate

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