Variation in Snow Algae Blooms in the Coast Range of British Columbia

Abstract

Snow algae blooms cover vast areas of summer snowfields worldwide, reducing albedo and increasing snow melt. Despite their global prevalence, little is known about the algae species that comprise these blooms. We used 18S and rbcL metabarcoding and light microscopy to characterize algae species composition in 31 snow algae blooms in the Coast Range of British Columbia, Canada. This study is the first to thoroughly document regional variation between blooms. We found all blooms were dominated by the genera Sanguina, Chloromonas, and Chlainomonas. There was considerable variation between blooms, most notably species assemblages above treeline were distinct from forested sites. In contrast to previous studies, the snow algae genus Chlainomonas was abundant and widespread in snow algae blooms. We found few taxa using traditional 18S metabarcoding, but the high taxonomic resolution of rbcL revealed substantial diversity, including OTUs that likely represent unnamed species of snow algae. These three cross-referenced datasets (rbcL, 18S, and microscopy) reveal that alpine snow algae blooms are more diverse than previously thought, with different species of algae dominating different elevations.

Alpine Snow Algae Microbiome Diversity in the Coast Range of British Columbia

“…In the current study, we set out to robustly document the microbial diversity in the mountains of Southwestern British Columbia. Previously, we reported that Sanguina and Chloromonas dominated distinct blooms and that they were found at different elevations (Engstrom et al, 2020). Based on the work of Terashima et al (2017) and Krug et al (2020), we predicted that specific microbial taxa would be associated with the distinct algal blooms.…”

“…The families of Ochorophyta detected included Chrysophyceae, Chrysocapsales, Mallomonadaceae, and Xanthophyceae. For a higher resolution analysis of the algal communities within our study region see Engstrom et al (2020).…”

Cysts of the Snow Alga Chloromonas krienitzii (Chlorophyceae) Show Increased Tolerance to Ultraviolet Radiation and Elevated Visible Light

“…The blooms occurred at open sites with elevation ranging from 1862 to 3500 m (this study), but earlier studies reported C. krienitzii to be predominant in clearings or sites with sparse trees around 1200 m (Engstrom et al, 2020) or at open sites in broad-leaf forest around 880 m elevation (R. Matsuzaki-pers. comm., Matsuzaki et al, 2015).…”

“…Individual species of snow algae can either show a cosmopolite distribution (e.g., S. nivaloides, Segawa et al, 2018;Procházková et al, 2019a) or their known occurrence is rather geographically limited (e.g., Chloromonas polyptera, Remias et al, 2013; Sanguina aurantia, Brown and Tucker, 2020). C. krienitzii seems to be in-between: It was initially described only from Japan (Matsuzaki et al, 2015) and subsequently found in Europe and North America as well (this study, Engstrom et al, 2020). Likely, the morphologically striking cysts have been observed many times elsewhere, but were determined as Chloromonas cf.…”

“…With samples from Japan, Matsuzaki et al (2015) described an independent taxon out of this group based on morphological data and the multigene phylogeny of the vegetative strain. Although this species was recently detected by environmental sequencing in British Columbia (Canada) (Engstrom et al, 2020), its overall geographic distribution is still unexplored.…”