Morphological and spectroscopic analysis of snow and glacier algae and their parasitic fungi on different glaciers of Svalbard

Abstract

The results show the morphological analyses and spectroscopic studies of snow and glacier algae and their parasitic fungi in Svalbard (High Arctic). Fixed algal cells of two species, Sanguina nivaloides and Ancylonema nordenskioeldii, were imaged using light microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Fluorescence microscopy using Calcofluor white stain supported the observations of parasitic fungi on the algal cells. Images in brightfield microscopy showed chytrid-like fungi penetrating the cells of both algal species. Parasites were found to colonize the cells of A. nordenskioeldii and hypnozygotes of S. nivaloides, while no fungi infected the cyst stages of S. nivaloides. The autofluorescence analysis revealed the ability of S. nivaloides to glow when excited with different wavelengths, while A. nordenskioeldii did not fluoresce. The hypnozygotes of S. nivaloides emitted brighter fluorescence than the cysts, and the most intense luminosity was observed in the UV range. The Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) spectroscopic analysis showed differences in the chemical composition between samples collected from three different sites. Samples dominated by cyst cells were characterized by the presence of an abundant polysaccharide envelope.

Sampling a gradient of red snow algae bloom density reveals novel connections between microbial communities and environmental features

“…Previous work indicates that Chytridiomycota can co-occur with snow algae 15 , 16 , 28 and may parasitize S. nivaloides hypnozygotes, but not cysts 49 . In this study, Chytridiomycotan OTUs constituted the largest relative abundance of all OTU sequences (28%), which was higher in the Cascades (91%) than the Rockies (9%).…”

Greenland Ice Sheet Surfaces Colonized by Microbial Communities Emit Volatile Organic Compounds

“…Four oxygenated benzenoids ( Table 8 ) were identified in bare ice surface VOC emissions, of which the three most emitted compounds (phenylmaleic anhydride, benzaldehyde, and acetophenone) have been reported to have antifungal activity ( Chen et al, 2011 ; Boukaew et al, 2018 ; Calvo et al, 2020 ). The presence of fungi on bare ice surfaces ( Perini et al, 2019 ) and recent evidence that parasitic fungi can penetrate the cells of snow and glacier ice algae, leading to their destruction ( Fiołka et al, 2021 ), suggests that algal production of antifungal VOCs may have an ecological advantage. The data presented here do not allow us to identify specific sources of measured VOCs, but it is a strong first indication that supraglacial microbial habitats are a source of microbial volatile emissions that should be investigated further in more controlled and long-term field sampling campaigns, as well studies in laboratory cultures of glacier surface species, as they become available.…”

Seasonal snowpack microbial ecology and biogeochemistry on a High Arctic ice cap reveals negligible autotrophic activity during spring and summer melt

“…These studies have given a great deal of attention to snow algae and glacier algae, not least due to their linkage with pigment-mediated albedo reduction and melt enhancement (Williamson et al, 2019;Gray et al, 2020;Mauro et al, 2020). Recently, there has been a shift from the aforementioned studies to the study of interactions between algae, fungi and bacteria (Krug et al, 2020;Fiołka et al, 2021). Although important, such approaches have offered little understanding of fundamental ecosystem characteristics, such as links to biogeochemical processes and the changing physical conditions of a snowpack during melt.…”