Abstract:Climate warming in Antarctica involves major shifts in plant distribution and productivity. This study aims to unravel the plasticity and acclimation potential of Bryum argenteum var. muticum, a cosmopolitan moss species found in Antarctica. By comparing short-term, closed-top chamber warming experiments which mimic heatwaves, with in situ seasonal physiological rates from Cape Hallett, Northern Victoria Land, we provide insights into the general inherent resilience of this important Antarctic moss and into it… Show more
“…This means that a better understanding of how respiration responds to rising temperatures is required in order to model the effect of different climate change scenarios on the long-term net CO 2 assimilation of Antarctic mosses and their survival. Light-saturated net CO 2 assimilation of Antarctic cosmopolitan B ryum argenteum increases under a short, simulated heat wave (Gemal et al 2022 ), although the long-term effect on carbon budget of an increase of respiration rates during warmer nights must also be considered.…”
Section: Introductionmentioning
confidence: 99%
“…Through these mechanisms, Antarctic mosses can achieve canopy temperatures of 20–30 °C in full sunlight when ambient air temperatures are close to 0 °C (Fig. 4 & 5 ; Longton and Holdgate 1967 ; Lewis Smith 1999 ; Perera-Castro et al 2020 ; Gemal et al 2022 ), especially on north and east facing topographic or micro-topographic aspects (Randall 2022 ). Fig.…”
Section: Introductionmentioning
confidence: 99%
“…Importantly, these warm microclimate conditions constitute new thermal climate conditions outside of the conditions provided by the broader climate (Fig. 6 ), extending the thermal range of the environment and providing opportunities for optimum photosynthesis that otherwise would not occur (Pannewitz et al 2005 ; Gemal et al 2022 ; Randall 2022 ). However, these maximum temperatures only occur for short windows of time when the mosses are in direct sunlight (Longton 1974 ; Pannewitz et al 2003 ), whereas most of the time photosynthesis is likely to be greatly depressed by cold temperatures (Kappen and Schroeter 2002 ; Pannewitz et al 2003 ; Perera-Castro et al 2020 ; Gemal et al 2022 ).…”
Section: Introductionmentioning
confidence: 99%
“…Warming to these temperatures is primarily driven by direct insolation (Longton and Holdgate 1967 ; Longton 1974 ; Kappen et al 1998 ; Perera-Castro et al 2020 ; Baker et al 2021 ; Gemal et al 2022 ; Randall 2022 ). Therefore, the ability for mosses to accumulate heat is heavily impacted by cloud and/or snow cover, which can inhibit mosses from warming above air temperatures (Fig.…”
Section: Introductionmentioning
confidence: 99%
“…4 ; Longton and Holdgate 1967 ), and limit opportunities for photosynthesis. Antarctica experiences some of the steepest shifts in seasonal solar angles and daylight hours worldwide (Pannewitz et al 2005 ; Convey et al 2014 ; Gemal et al 2022 ). Solar elevation (zenith) angles are much lower to the horizon compared to lower latitudes, reducing the quantity of light that reaches the ground where Antarctic mosses grow.…”
The Antarctic environment is extremely cold, windy and dry. Ozone depletion has resulted in increasing ultraviolet-B radiation, and increasing greenhouse gases and decreasing stratospheric ozone have altered Antarctica’s climate. How do mosses thrive photosynthetically in this harsh environment? Antarctic mosses take advantage of microclimates where the combination of protection from wind, sufficient melt water, nutrients from seabirds and optimal sunlight provides both photosynthetic energy and sufficient warmth for efficient metabolism. The amount of sunlight presents a challenge: more light creates warmer canopies which are optimal for photosynthetic enzymes but can contain excess light energy that could damage the photochemical apparatus. Antarctic mosses thus exhibit strong photoprotective potential in the form of xanthophyll cycle pigments. Conversion to zeaxanthin is high when conditions are most extreme, especially when water content is low. Antarctic mosses also produce UV screening compounds which are maintained in cell walls in some species and appear to protect from DNA damage under elevated UV-B radiation. These plants thus survive in one of the harshest places on Earth by taking advantage of the best real estate to optimise their metabolism. But survival is precarious and it remains to be seen if these strategies will still work as the Antarctic climate changes.
“…This means that a better understanding of how respiration responds to rising temperatures is required in order to model the effect of different climate change scenarios on the long-term net CO 2 assimilation of Antarctic mosses and their survival. Light-saturated net CO 2 assimilation of Antarctic cosmopolitan B ryum argenteum increases under a short, simulated heat wave (Gemal et al 2022 ), although the long-term effect on carbon budget of an increase of respiration rates during warmer nights must also be considered.…”
Section: Introductionmentioning
confidence: 99%
“…Through these mechanisms, Antarctic mosses can achieve canopy temperatures of 20–30 °C in full sunlight when ambient air temperatures are close to 0 °C (Fig. 4 & 5 ; Longton and Holdgate 1967 ; Lewis Smith 1999 ; Perera-Castro et al 2020 ; Gemal et al 2022 ), especially on north and east facing topographic or micro-topographic aspects (Randall 2022 ). Fig.…”
Section: Introductionmentioning
confidence: 99%
“…Importantly, these warm microclimate conditions constitute new thermal climate conditions outside of the conditions provided by the broader climate (Fig. 6 ), extending the thermal range of the environment and providing opportunities for optimum photosynthesis that otherwise would not occur (Pannewitz et al 2005 ; Gemal et al 2022 ; Randall 2022 ). However, these maximum temperatures only occur for short windows of time when the mosses are in direct sunlight (Longton 1974 ; Pannewitz et al 2003 ), whereas most of the time photosynthesis is likely to be greatly depressed by cold temperatures (Kappen and Schroeter 2002 ; Pannewitz et al 2003 ; Perera-Castro et al 2020 ; Gemal et al 2022 ).…”
Section: Introductionmentioning
confidence: 99%
“…Warming to these temperatures is primarily driven by direct insolation (Longton and Holdgate 1967 ; Longton 1974 ; Kappen et al 1998 ; Perera-Castro et al 2020 ; Baker et al 2021 ; Gemal et al 2022 ; Randall 2022 ). Therefore, the ability for mosses to accumulate heat is heavily impacted by cloud and/or snow cover, which can inhibit mosses from warming above air temperatures (Fig.…”
Section: Introductionmentioning
confidence: 99%
“…4 ; Longton and Holdgate 1967 ), and limit opportunities for photosynthesis. Antarctica experiences some of the steepest shifts in seasonal solar angles and daylight hours worldwide (Pannewitz et al 2005 ; Convey et al 2014 ; Gemal et al 2022 ). Solar elevation (zenith) angles are much lower to the horizon compared to lower latitudes, reducing the quantity of light that reaches the ground where Antarctic mosses grow.…”
The Antarctic environment is extremely cold, windy and dry. Ozone depletion has resulted in increasing ultraviolet-B radiation, and increasing greenhouse gases and decreasing stratospheric ozone have altered Antarctica’s climate. How do mosses thrive photosynthetically in this harsh environment? Antarctic mosses take advantage of microclimates where the combination of protection from wind, sufficient melt water, nutrients from seabirds and optimal sunlight provides both photosynthetic energy and sufficient warmth for efficient metabolism. The amount of sunlight presents a challenge: more light creates warmer canopies which are optimal for photosynthetic enzymes but can contain excess light energy that could damage the photochemical apparatus. Antarctic mosses thus exhibit strong photoprotective potential in the form of xanthophyll cycle pigments. Conversion to zeaxanthin is high when conditions are most extreme, especially when water content is low. Antarctic mosses also produce UV screening compounds which are maintained in cell walls in some species and appear to protect from DNA damage under elevated UV-B radiation. These plants thus survive in one of the harshest places on Earth by taking advantage of the best real estate to optimise their metabolism. But survival is precarious and it remains to be seen if these strategies will still work as the Antarctic climate changes.
Because of climate change, the McMurdo Dry Valleys of Antarctica (MCM) have experienced an increase in the frequency and magnitude of summer pulse warming and surface ice and snow melting events. In response to these environmental changes, some nematode species in the MCM have experienced steady population declines over the last three decades, but Plectus murrayi, a mesophilic nematode species, has responded with a steady increase in range and abundance. To determine how P. murrayi responds to increasing temperatures, we measured metabolic heat and CO2 production rates and calculated O2 consumption rates as a function of temperature at 5 °C intervals from 5 to 50 °C. Heat, CO2 production, and O2 consumption rates increase approximately exponentially up to 40 °C, a temperature never experienced in their polar habitat. Metabolic rates decline rapidly above 40 °C and are irreversibly lost at 50 °C due to thermal stress and mortality. Caenorhabditis elegans, a much more widespread nematode that is found in more temperate environments reaches peak metabolic heat rate at just 27 °C, above which it experiences high mortality due to thermal stress. At temperatures from 10 to 40 °C, P. murrayi produces about 6 times more CO2 than the O2 it consumes, a respiratory quotient indicative of either acetogenesis or de novo lipogenesis. No potential acetogenic microbes were identified in the P. murrayi microbiome, suggesting that P. murrayi is producing increased CO2 as a byproduct of de novo lipogenesis. This phenomenon, in conjunction with increased summer temperatures in their polar habitat, will likely lead to increased demand for carbon and subsequent increases in CO2 production, population abundance, and range expansion. If such changes are not concomitant with increased carbon inputs, we predict the MCM soil ecosystems will experience dramatic declines in functional and taxonomic diversity.
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