Abstract

The quantity, distribution and contribution to primary productivity of snow algae in Antarctica are currently unknown. Snow algae communities consist mainly of green algal species of the genera Chlamydomonas and Chloromonas. They have a bi-phasic life cycle consisting of an active reproductive motile stage, seen as green patches in the snow, and a dormant encystment phase during which the cells accumulate the red keto-carotenoid astaxanthin, giving rise to red snow patches. We measured the metabolic composition of snow algae in both green and red phases, from samples taken in the field at various locations in Antarctica during the 2014/15 and 2017/18 austral summer seasons. We also determined the community composition of the blooms using 16S and 18S metagenomic sequencing. Our data showed that the metabolic composition of the cells was the same from four geologically distinct but spatially close locations in the vicinity of Ryder Bay (Adelaide Island, 68°S). However, our data also show a high degree of patchiness in the snow melt between the locations where snow algae communities occurred. Our metabolite data showed that the snow algae were rich in unsaturated fatty acids and that metabolomic assays could detect detailed changes in lipid, carbohydrate and protein chemistry in the cells during encystment. I will also present the first remote sensing analysis of snow algae distribution in Ryder Bay (Adelaide Island, Antarctic Peninsula, 68°S) using a detection algorithm for satellite data and will present updates from our 2019 Antarctic field season at King George Island – linking remote sensing data to the blooms on the ground and future plans.

After his talk and question session Matt has kindly offered to give an additional 10-15min talk on the wildlife and “life on base” in Antarctica.