Similar heterotrophic communities but distinct interactions supported by red and green-snow algae in the Antarctic Peninsula

Snow algae are predicted to expand in polar regions due to climate warming, which can accelerate snowmelt by reducing albedo. Green snow frequently occurs near penguin colonies, and red snow distributes widely along ocean shores. However, the mechanisms underpinning the assemblage of algae and heterotrophs in colored snow remain poorly characterized. We investigated algal, bacterial, and fungal communities and their interactions in red and green snows in the Antarctic Peninsula using a high-throughput sequencing method. We found distinct algal community structure in red and green snows, and the relative abundance of dominant taxa varied, potentially due to nutrient status differences. Contrastingly, red and green snows exhibited similar heterotrophic communities (bacteria and fungi), whereas the relative abundance of fungal pathogens was substantially higher in red snow by 3.8-fold. Red snow exhibited a higher network complexity, indicated by a higher number of nodes and edges. Red snow exhibited a higher proportion of negative correlations among heterotrophs (62.2% vs 3.4%) and stronger network stability, suggesting the red-snow network is more resistant to external disturbance. Our study revealed that the red snow microbiome exhibits a more stable microbial network than the green snow microbiome.