Cosmopolitan and endemic species jointly enhance the potential of producing algal blooms in Tibetan glaciers

Snow algal blooms lead to glacier and snow surface albedo reduction and subsequent melting. To explore snow algal distribution patterns and potential to cause blooms, we investigated snow algae in the Tibetan, Antarctic, Arctic, and Alps. Our results demonstrated that Tibetan and Alps had higher algal richness than Antarctic snow. Only 19 ASVs were shared among regions, with their relative abundance being lower in the Tibetan compared to the Arctic and Alps but similar in Antarctica. Furthermore, the algal community varied substantially across sampling sites, with 34% of the identified taxa endemic to Tibetan glacier snow. Cosmopolitan bloom-causing algae were scarce in most Tibetan Plateau snow, which was potentially limited by a low snow depth that prevented their growth. Alternatively, Hydrurus sp., which may cause golden-brown snow, was abundant (up to 54.4%) on Tibetan. Therefore, cosmopolitan and endemic species jointly enhance the potential of producing algal blooms in Tibetan glaciers. Cosmopolitan bloom-causing algae are rare in Tibetan Plateau glaciers due to shallow snow, but their presence along with abundant endemic snow algae enhances the potential of future algal blooms, based on high-throughput sequencing of snow algae from 13 Tibetan glaciers compared to global samples.