Remote sensing reveals Antarctic green snow algae as important terrestrial carbon sink

Abstract

We present the first estimate of green snow algae community biomass and distribution along the Antarctic Peninsula. Sentinel 2 imagery supported by two field campaigns revealed 1679 snow algae blooms, seasonally covering 1.95 × 10 6 m 2 and equating to 1.3 × 10 3 tonnes total dry biomass. Ecosystem range is limited to areas with average positive summer temperatures, and distribution strongly influenced by marine nutrient inputs, with 60% of blooms less than 5 km from a penguin colony. A warming Antarctica may lose a majority of the 62% of blooms occupying small, low-lying islands with no high ground for range expansion. However, bloom area and elevation were observed to increase at lower latitudes, suggesting that parallel expansion of bloom area on larger landmasses, close to bird or seal colonies, is likely. This increase is predicted to outweigh biomass lost from small islands, resulting in a net increase in snow algae extent and biomass as the Peninsula warms.

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

“…However, the relationship is not consistent across the full range of data shown. Gray et al (2020) also note that red algae can alter the derived relationship compared to green algae.…”

“…. Mean daily RF was highest around Ordinal Day 300 and declining after Day 350 Gray et al, (2020). estimated a 122-day growing season.…”

“…and near infrared (Band 5, 704 nm). Following Painter et al (2001) and Gray et al (2020), a scaled integral of Sentinel 2's…”

“…On Greenland, Wang et al (2018) used Sentinel-3 imagery to map the spatial pattern of glacier algae using the reflectance ratios between 709 nm and 673 nm. Within the AP region, spectral mixture analysis with Sentinel 2 imagery can more reliably classify snow algae when other LAPs are present (Huovinen et al, 2018) and multi-year mosaics have identified green-snow as a terrestrial carbon sink (Gray et al, 2020). We build on these pioneering studies by presenting new approaches to spectrally distinguish red from green snow algae and further evaluate the RF of snow algae based on environmental conditions in this part of Antarctica.…”

The Vegetation of the South Shetland Islands and the Climatic Change

“…It is important to note that a considerable carbon reservoir exists in cryobiont algae, which form extensive colonies directly on the ice. With the increase in temperature, it is expected that 62% of the blooms of small islands (like in the South Shetland archipelago) of low altitude will disappear [11].…”