Resilience and recovery of Bratina Island meltwater pond microbial communities to environmental change

Abstract

16S rRNA sequencing of three Bratina Island meltwater ponds has revealed the response of microbial communities within cyanobacterial mats exposed to shading and desiccation as environmental stressors. The resilience of these communities is perhaps not surprising considering the extreme environmental conditions they consistently face in these habitats. It was postulated that cyanobacteria will remain the dominant primary producers across the ponds when exposed to shading and desiccation, because they are known to possess adaptations to these stresses. Similar to research in other studies, it was found that three phyla: Cyanobacteria, Bacteroidota and Proteobacteria make up the majority of the diversity in these communities, but their dominance shifted between shading and desiccation samples. The most obvious changes occurred in desiccation samples, where the abundance of cyanobacteria dropped to less than 10% in some samples. Predicted functional changes in gene sets involved in photosynthesis and methanogenesis were also investigated, and unexpectedly, predicted functional changes in methanogenesis only occurred in one pond. This thesis describes the microbial ecology of Bratina Island meltwater ponds, and the effect of desiccation and shading as environmental stressors on the diversity. It also addresses potential functional changes within these communities. Although, more extensive research into archaeal and eukaryotic communities alongside changes in physiochemical parameters within each pond is needed to fully understand how shading and desiccation effects the resilience and resistance of microbial communities within meltwater ponds.