Hydrurus‐related golden algae (Chrysophyceae) cause yellow snow in polar summer snowfields

Abstract

SUMMARYIn polar regions, melting snow fields can be occupied by striking blooms of chrysophycean algae, which cause yellowish slush during summer. Samples were harvested at King George Island (South Shetland Islands, Maritime Antarctica) and at Spitsbergen (Svalbard archipelago, High Arctic). The populations live in an ecological niche, where water-logged snow provides a cold and ephemeral ecosystem, possibly securing the survival of psychrophilic populations through the summer. A physiological adaptation to low temperatures was shown by photosynthesis measurements. The analysis of soluble carbohydrates showed the occurrence of glycerol and sugars, which may play a role in protection against intracellular freezing. Although both populations were made of unicells with Ochromonasalike morphology, investigation by molecular methods (18S rDNA sequencing) revealed unexpectedly a very close relationship to the mountain-river dwelling Hydrurus foetidus (Villars) Trevisan. However, macroscopic thalli typical for the latter species were never found in snow, but are known from nearby localities, and harvested samples of snow algae exposed to dryness evolved a similar pervading, 'fishy' smell. Moreover, in both habitats tetrahedal zoospores with four elongate spikes were found, similar to what is known from Hydrurus. Our molecular results go along with earlier reports, where chrysophycean sequences of the same taxonomic affiliation were isolated from snow. This points to a distinct group of photoautotrophic, Hydrurus-related chrysophytes, which are characteristic for long-lasting, slowly melting snow packs in certain cold regions of the world.

The diversity of ice algal communities on the Greenland Ice Sheet as revealed by oligotyping

“…The exception was the clean snow sample collected at the most inland location site ~100 km away from the base camp (GrIS16_1). The community composition in this sample was almost entirely (96 %) made up by the Chrysophyceae taxon Hydrurus , previously found to be responsible for the less-often described ‘yellow snow’ [ 54 ]. This sample, however, contained the fewest sequences that could be assigned to algal taxa (sequences were mostly assigned to fungi; Table S1), a characteristic that may indicate a very low algal biomass.…”

Remote sensing reveals Antarctic green snow algae as important terrestrial carbon sink

“…Red and/or orange snow algae blooms (such as Sanguina sp., Chloromonas polyptera and Hydrurus sp.) are also a dominant ecosystem alongside, or even incorporated within, some green blooms 4,9,10,32 . However, in spite of their importance such dominant red or orange blooms had to be excluded from our study as absorbance from secondary carotenoids such as astaxanthin, present in red but not all green cells 33 , reduces the reflectance of Band 3 and flattens any chlorophyll absorbance feature within Sentinel 2 bands, making them difficult to detect automatically (see Supplementary Fig.…”

The microbiome of alpine snow algae shows a specific inter-kingdom connectivity and algae-bacteria interactions with supportive capacities

“…Spumella- like flagellates ( Chrysophyceae ), predominant on orange snowfields, were identified among other members of the Chrysophyceae class in previous studies. The coloration was found to be due to pigments involved in the xanthophyll cycle, which is used by chrysophytes snow algae to cope with excessive light energy [ 52 , 53 ].…”