Pigment signatures of algal communities and their implications for glacier surface darkening

TY - JOUR

T1 - Pigment signatures of algal communities and their implications for glacier surface darkening

AU - Halbach, Laura

AU - Chevrollier, Lou Anne

AU - Doting, Eva L.

AU - Cook, Joseph M.

AU - Jensen, Marie B.

AU - Benning, Liane G.

AU - Bradley, James A.

AU - Hansen, Martin

AU - Lund-Hansen, Lars C.

AU - Markager, Stiig

AU - Sorrell, Brian K.

AU - Tranter, Martyn

AU - Trivedi, Christopher B.

AU - Winkel, Matthias

AU - Anesio, Alexandre M.

N1 - Publisher Copyright: © 2022, The Author(s).

PY - 2022/10

Y1 - 2022/10

N2 - Blooms of pigmented algae darken the surface of glaciers and ice sheets, thereby enhancing solar energy absorption and amplifying ice and snow melt. The impacts of algal pigment and community composition on surface darkening are still poorly understood. Here, we characterise glacier ice and snow algal pigment signatures on snow and bare ice surfaces and study their role in photophysiology and energy absorption on three glaciers in Southeast Greenland. Purpurogallin and astaxanthin esters dominated the glacier ice and snow algal pigment pools (mass ratios to chlorophyll a of 32 and 56, respectively). Algal biomass and pigments impacted chromophoric dissolved organic matter concentrations. Despite the effective absorption of astaxanthin esters at wavelengths where incoming irradiance peaks, the cellular energy absorption of snow algae was 95% lower than anticipated from their pigmentation, due to pigment packaging. The energy absorption of glacier ice algae was consequently ~ 5 × higher. On bare ice, snow algae may have locally contributed up to 13% to total biological radiative forcing, despite contributing 44% to total biomass. Our results give new insights into the impact of algal community composition on bare ice energy absorption and biomass accumulation during snow melt.

AB - Blooms of pigmented algae darken the surface of glaciers and ice sheets, thereby enhancing solar energy absorption and amplifying ice and snow melt. The impacts of algal pigment and community composition on surface darkening are still poorly understood. Here, we characterise glacier ice and snow algal pigment signatures on snow and bare ice surfaces and study their role in photophysiology and energy absorption on three glaciers in Southeast Greenland. Purpurogallin and astaxanthin esters dominated the glacier ice and snow algal pigment pools (mass ratios to chlorophyll a of 32 and 56, respectively). Algal biomass and pigments impacted chromophoric dissolved organic matter concentrations. Despite the effective absorption of astaxanthin esters at wavelengths where incoming irradiance peaks, the cellular energy absorption of snow algae was 95% lower than anticipated from their pigmentation, due to pigment packaging. The energy absorption of glacier ice algae was consequently ~ 5 × higher. On bare ice, snow algae may have locally contributed up to 13% to total biological radiative forcing, despite contributing 44% to total biomass. Our results give new insights into the impact of algal community composition on bare ice energy absorption and biomass accumulation during snow melt.

UR - http://www.scopus.com/inward/record.url?scp=85140337975&partnerID=8YFLogxK

U2 - 10.1038/s41598-022-22271-4

DO - 10.1038/s41598-022-22271-4

M3 - Journal article

C2 - 36271236

AN - SCOPUS:85140337975

SN - 2045-2322

VL - 12

JO - Scientific Reports

JF - Scientific Reports

M1 - 17643

ER -