Primary productivity of snow algae communities on stratovolcanoes of the Pacific Northwest

Abstract

The majority of geomicrobiological research conducted on glacial systems to date has focused on glaciers that override primarily carbonate or granitic bedrock types, with little known of the processes that support microbial life in glacial systems overriding volcanic terrains (e.g., basalt or andesite). To better constrain the role of the supraglacial ecosystems in the carbon and nitrogen cycles, to gain insight into microbiome composition and function in alpine glacial systems overriding volcanic terrains, and to constrain potential elemental sequestration or release through weathering processes associated with snow algae communities, we examined the microbial community structure and primary productivity of snow algae communities on stratovolcanoes in the Cascade Range of the Pacific Northwest. Here, we present the first published values for carbon fixation rates of snow algae communities on glaciers in the Pacific Northwest. We observed varying levels of light‐dependent carbon fixation on supraglacial and periglacial snowfields at Mt. Hood, Mt. Adams, and North Sister. Recovery of abundant 18S rRNA transcripts affiliated with photoautotrophs and 16S rRNA transcripts affiliated with heterotrophic bacteria is consistent with previous studies indicating the majority of primary productivity on snow and ice can be attributed to photoautotrophs. In contrast to previous observations of glacial ecosystems, our geochemical, isotopic, and microcosm data suggest these assemblages are not limited by phosphorus or fixed nitrogen availability. Furthermore, our data indicate these snow algae communities actively sequester Fe, Mn, and P leached from minerals sourced from the local rocks. Our observations of light‐dependent primary productivity on snow are consistent with similar studies in polar ecosystems; however, our data may suggest that DIC may be a limiting nutrient in contrast to phosphorus or fixed nitrogen as has been observed in other glacial ecosystems. Our data underscore the need for similar studies on glacier surfaces and seasonal snowfields to better constrain the role of local bedrock and nutrient delivery on carbon fixation and biogeochemical cycling in these ecosystems.

The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

“…In contrast, Fujii et al 26 attributed Antarctic snow-alga distribution and abundance to allochthonous bird deposition of limiting nutrients. A field microcosm study on North American volcanoes 27 found no NP-enrichment effect on snow-alga abundance, while a laboratory microcosm of Greenland cryoconite debris 17 showed NPenrichment doubled both organic carbon and chlorophyll-a. Here, the response to NPK-enrichment in 2-m 2 plots exceeds the mean response of approximately 3.4× reported for pelagic phytoplankton in NP-enriched freshwater lakes 28 .…”

“…A single pulse of N-enrichment in-frame at the start of interval photography on the Eklutna Glacier also suggested a response of red-snow algae to nutrient enrichment, with earlier, more intensely red-coloured snow at and near the enrichment point (Supplementary Movie). Previous field observations 16,26 and in vitro microcosm nutrient additions 17,27 suggest that nutrient limitation in snow algae is study-dependent. For example, Lutz et al 16 in a wide-ranging Arctic study found no correlation between alga abundance and nutrient concentrations in filtered red snow.…”

Silica Dissolution and Precipitation in Glaciated Volcanic Environments and Implications for Mars

“…Eliot Glacier is a 1.6-km 2 glacier on the northeast flank of Mt. Hood adjacent to and partly overlying dacitic block and ash flows (Crandell, 1980;Hamilton & Havig, 2017;Jackson & Fountain, 2007).…”

Snow algae communities in Antarctica: metabolic and taxonomic composition

“…With habitat regression, or if areas of snow melt completely early in the summer, the ecosystem may be lost entirely for that season (Convey, 2011;Anesio et al, 2017). Whichever outcome prevails which is likely to vary with locationthere is an urgent need to study these polar communities to provide a balanced view of polar terrestrial biodiversity and to avoid the loss of these extremophilic primary producers and their community structure at both local and continental scales (Williams et al, 2003;Rogers et al, 2007;Hamilton & Havig, 2017;Rintoul et al, 2018). This is especially pertinent because, although snow algae may not be endemic, there is evidence of endemism and long-term evolutionary isolation in other associated microbial species and communities around Antarctica, probably due to the geographical isolation of the continent (Vyverman et al, 2010;Remias et al, 2013;Cavicchioli, 2015;Petz et al, 2007).…”