Marked Seasonal Changes in the Microbial Production, Community Composition, and Biogeochemistry of Glacial Snowpack Ecosystems in the Maritime Antarctic

Abstract

 Regional nutrient enrichment by marine fauna influences the microbial ecology of glacial snowpacks in the maritime Antarctic during summer. Cold summers with low melt and frequent snowfall reduce photosynthesis at the surface and allow bacterial production to dominate. Persistent moisture supply to penguin guano enhances the effects of ammonium and organic acid deposition onto the snow ecosystem.

Seasonal Snowpack Microbial Ecology and Biogeochemistry on a High Arctic Ice Cap Reveals Negligible Autotrophic Activity During Spring and Summer Melt

“…Therefore utilization of these nutrients by the resident autotrophic communities was a dominant feature of the Livingston Island data set (Hodson et al, 2017). Similar, order of magnitude changes in chlorophyll a concentrations were also observed in nutrient-enriched glacial snowpacks of Signy Island in the maritime Antarctic (Hodson et al, 2021). Here, flow cytometry analysis revealed a high autotrophic abundance (nearly 10 5 cells mL −1 ) at a chlorophyll a concentration of ∼1 μg L −1 .…”

“…(2017) provided evidence for differences detectable not only in the microbial community composition, but also the biomass and nutrients of coastal and inland (glacial) snowpacks, thereby highlighting changes over short distances (<1 km). A new study, carried out upon another maritime Antarctic glacier (Signy Island), also revealed such differences between two coastal sites, as well as within the vertical profile of a glacial snowpack with a substantial SI layer (Hodson et al., 2021). In this context, snowpack stratification and its effects on resident microbes and nutrients could be significant.…”

Frozen Clay Minerals as a Potential Source of Bioavailable Iron and Magnetite

“…Further, environmental conditions with high acidity and ice formation also exist in polar regions. Snowpacks in Antarctica typically exhibit acidic conditions, and a pH of approximately 3.3 has been reported . It was also reported that the pH of streamwater in Antarctica can range from pH 3.2 to 4.5 in the presence of acid mine drainage .…”

“…Snowpacks in Antarctica typically exhibit acidic conditions, and a pH of approximately 3.3 has been reported. 90 It was also reported that the pH of streamwater in Antarctica can range from pH 3.2 to 4.5 in the presence of acid mine drainage. 91 The Antarctic acid mine drainage regions have conditions conducive to these reactions, including the presence of ice and clay minerals, the potential influx of iodide from the ocean, and a pH that can be as low as 3.…”

Seasonal changes in the viability of bacterial cells in the snowpack ecosystem of a High Arctic ice cap

“…We therefore compared the viability of microorganisms in the winter snow accumulation to the underlying glacial ice in order to deduce whether the predominant role of glacial runoff is the delivery of viable or non-viable cells to downstream ecosystems (Mindl et al, 2007;Hood et al, 2009). We also considered the role of the transient refrozen snowmelt layer (or "superimposed ice") that forms upon the cold glacier surface after the onset of snowmelt in summer because, while superimposed ice is often an important ecosystem in its own right (e.g., Hodson et al, 2021), the refreezing process might contribute to cell mortality. Therefore, by better understanding whether cells remain alive and viable prior to export, we can begin to quantify their role in the transformation and turnover of nutrients and the linkages between glacial and downstream ecosystems better understood.…”