Almela Pablo, Elser James J, Giersch J Joseph, Hotaling Scott, Hamilton Trinity L
Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA.
Flathead Lake Biological Station, University of Montana, Polson, Montana, USA.
mBio. 2025 Feb 5;16(2):e0363024. doi: 10.1128/mbio.03630-24. Epub 2025 Jan 14.
Snow algae darken the surface of snow, reducing albedo and accelerating melt. However, the impact of subsurface snow algae (e.g., when cells are covered by recent snowfall) on albedo is unknown. Here, we examined the impact of subsurface snow algae on surface energy absorption by adding up to 2 cm of clean snow to surface algal blooms and measuring reflectivity. Surprisingly, snow algae still absorb significant energy across an array of wavelengths when snow-covered. Furthermore, the scale of this effect correlates with algal cell densities and chlorophyll-a concentrations. Collectively, our results suggest that darkening by subsurface snow algae lowers albedo and thus potentially accelerates snowmelt even when the algae is snow-covered. Impacts of subsurface algae on melt await assessment. This implies that snow algae play a larger role in cryosphere melt than investigations of surface-only reflectance would suggest.
This study addresses a gap in research by examining the impact of subsurface snow algae on snow albedo, which affects snowmelt rates. Previous studies have focused on visible surface blooms, leaving the effects of hidden algae unquantified. Our findings reveal that snow algae beneath the surface can still absorb energy across various wavelengths, accelerating melt even when not visible to the naked eye. This suggests that spectral remote sensing can detect these hidden algae, although their biomass might be underestimated. Understanding how subsurface snow algae influence albedo and snowmelt is crucial for accurate predictions of meltwater runoff, which impacts alpine ecosystems, glacier health, and water resources. Accurate projections are essential for managing freshwater supplies for agriculture, drinking water, and other vital uses. Thus, further investigation into subsurface snow algae is necessary to improve our understanding of their role in snow albedo reduction and water resource management.
雪藻会使雪面颜色变深，降低反照率并加速融化。然而，地下雪藻（例如，当细胞被新降雪覆盖时）对反照率的影响尚不清楚。在这里，我们通过在表层藻华上添加至多2厘米厚的干净雪并测量反射率，研究了地下雪藻对表面能量吸收的影响。令人惊讶的是，当被雪覆盖时，雪藻在一系列波长范围内仍能吸收大量能量。此外，这种效应的规模与藻类细胞密度和叶绿素a浓度相关。总体而言，我们的结果表明，即使藻类被雪覆盖，地下雪藻导致的颜色变深也会降低反照率，从而可能加速融雪。地下藻类对融化的影响有待评估。这意味着雪藻在冰冻圈融化中所起的作用比仅研究表面反射率的研究所表明的更大。
本研究通过研究地下雪藻对雪反照率的影响来填补研究空白，雪反照率会影响融雪速率。以往的研究集中在可见的表层藻华，而隐藏藻类的影响尚未量化。我们的研究结果表明，表面以下的雪藻仍能在各种波长下吸收能量，即使肉眼不可见也会加速融化。这表明光谱遥感可以检测到这些隐藏的藻类，尽管它们的生物量可能被低估。了解地下雪藻如何影响反照率和融雪对于准确预测融水径流至关重要，融水径流会影响高山生态系统、冰川健康和水资源。准确的预测对于管理农业、饮用水和其他重要用途的淡水供应至关重要。因此，有必要进一步研究地下雪藻，以增进我们对它们在降低雪反照率和水资源管理中作用的理解。
