Spatiotemporal Diversity of Alpine Snow Algae Communities in the Pacific Northwest

Snow algae are the dominant primary producers of snowy alpine environments and have recently been thrust into the public spotlight for contributing to glacial melt by decreasing snow albedo. These microbial communities are subject to extreme temperature regimes, high irradiance, low nutrient levels, and freeze-thaw cycles on daily, seasonal, and even long-term climatological changes. Although snow algae have been described on every continent, the spatiotemporal diversity of snow algae communities across snowy habitats has not been addressed. The natural geography and climate of the Pacific Northwest provides diverse snowy alpine ecosystems to study the effects of latitude, elevation, and precipitation on snow algae communities. Using meta-amplicon sequencing of the 18S small subunit ribosomal gene, I describe patterns in the community structure of snow algae communities in the Pacific Northwest Cascade Mountains. Collectively, the amplicon data suggest that snow algae communities can be classified in distinct assemblages of both algal and heterotrophic communities that are distributed across the Cascades. I observe a general seasonal algal succession from early season Chloromonas spp. dominant communities to late season Chlamydomonas spp. dominant communities in both large geographic context and within a single basin. Additionally, I observe a late season increase in the relative abundance of heterotrophic taxa and an increase in overall community diversity. My data suggest that algae community structure may vary in accordance with the dynamic environment in which they live and thus the community of snow microbes are selected for by the environment or microhabitat in which they live. The algal assemblages that I describe give insight to these understudied ecosystems which are extremely important in our warming climate.