Basking in the sun: how mosses photosynthesise and survive in Antarctica

Abstract

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.

Extended ozone depletion and reduced snow and ice cover—Consequences for Antarctic biota

“…The availability of melt water causes biota to exit winter dormancy, and many organisms are more vulnerable to UV‐B damage when metabolically active than when desiccated and dormant (Turnbull et al., 2009; Turnbull & Robinson, 2009). The recent trend towards late closing of the ozone hole over Antarctica has caused a shift in the high UV radiation exposure period to a time where terrestrial organisms are emerging from winter snow cover and are more likely to be exposed (Yin et al., 2023). Plants emerging in late spring could now be immediately exposed to the maximum UV Index of 14, whereas prior to ozone depletion the highest UV Index experienced at this time of the year was 6 (Figure 1b).…”

Monitoring of Antarctica’s Fragile Vegetation Using Drone-Based Remote Sensing, Multispectral Imagery and AI

“…The Windmill Islands coastline in East Antarctica is home to some of the largest “moss forests” on the continent. These moss forests experience extremes of temperature, light and water [ 2 , 3 , 4 ]. The growth and health of Antarctic moss beds relies heavily on the availability of liquid melt water from snow and ice, which is unreliable from year to year and over the course of the summer season [ 3 ].…”

“…These moss forests experience extremes of temperature, light and water [ 2 , 3 , 4 ]. The growth and health of Antarctic moss beds relies heavily on the availability of liquid melt water from snow and ice, which is unreliable from year to year and over the course of the summer season [ 3 ]. The supply of liquid water is likely to become more unreliable for Antarctic mosses under continuing climate change, as snow banks retreat and precipitation patterns change [ 5 ].…”

A Green Fingerprint of Antarctica: Drones, Hyperspectral Imaging, and Machine Learning for Moss and Lichen Classification

“…Antarctica is home to a unique and diverse ecosystem that is sensitive to climate change, extreme events, and human activities [1][2][3][4][5][6][7][8][9]. Vegetation, such as mosses and lichens, plays a vital role in maintaining the ecological balance, insulating ice-free soils, biogeochemical cycling, and providing habitat for much of Antarctica's terrestrial biodiversity [3,[10][11][12][13][14][15]. However, mapping and monitoring vegetation in Antarctica presents challenges due to its remoteness, harsh environment, limited accessibility, and a changing climate [2,6,16,17].…”

“…This study addresses these gaps by introducing and validating a workflow that enables remote sensing of vegetation in extreme environments using UAVs, MSI and HSI data, and supervised ML classification. The workflow encompasses five pivotal phases: (1) data collection; (2) data preparation; (3) feature extraction; (4) model training; and (5) prediction. This approach underwent testing in a case study focusing on lichen detection and moss health classification in an Antarctic Specially Protected Area (ASPA) 135 [30], situated on the Bailey Peninsula in the Windmill Islands region of East Antarctica.…”