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81-3 Microbial mat primary productivity and pore water microenvironments controlled by changing ice cover attributes in a perennially ice-covered lake of the McMurdo Dry Valleys, Antarctica

Session: New Advances in Geomicrobiology

Presenting Author:

Tyler Mackey

Authors:

Mackey, Tyler James¹, Kohl, Jove², Juarez Rivera, Marisol³, Judge, Lauren⁴, Takacs-Vesbach, Cristina⁵, Morgan-Kiss, Rachael⁶, Doran, Peter⁷, Dugan, Hilary⁸, Lawrence, Jade⁹, Gooseff, Michael N.¹⁰r> (1) University of New Mexico, Albuquerque, NM, , (2) University of New Mexico, Albuquerque, NM, USA, (3) University of New Mexico Earth and Planetary Sciences X-ray Computed Tomography, USA, (4) University of New Mexico, Albuquerque, NM, USA, (5) University of New Mexico, Albuquerque, NM, USA, (6) Miami University of Ohio, Oxford, OH, USA, (7) Louisiana State University, Baton Rouge, LA, USA, (8) University of Wisconsin-Madison, Madison, WI, USA, (9) University of New Mexico, Albuquerque, NM, , (10) University of Colorado, Boulder, CO, USA,

Abstract:

The majority of net primary productivity in the polar desert ecosystems of the McMurdo Dry Valleys, Antarctica, takes place in microbial mats of meltwater streams or perennially ice-covered lakes (PICLs), which have seasonal liquid moats on the lake edge and perennial liquid water under the ice cover. Microbial mats across these habitats are sensitive to changing climate of the region, including both increased stream melt with resulting lake level rise and variation in the thickness of the perennial ice cover. In this contribution, we investigate the relative role of lake level and ice cover on benthic mat primary productivity in Lake Fryxell to assess the potential implications of future change on these microbially-dominated ecosystems. Conditions in regional lakes have been monitored by the McMurdo Dry Valleys Long Term Ecological Research project since 1993, and long-term data sets demonstrate that ice cover thickness and transmissivity has a stronger control on total surface area for net mat growth than changes in lake level.

Changes in ice cover thickness also affect the patterns of sedimentation in PICLs; aeolian sands are deposited on the PICL ice cover, and grains annually melt through thinner ice covers but accumulate within thicker ice covers before episodically working their way through the ice to form discrete sand mounds. Patterns of sand deposition have the potential to affect the local light environment in benthic mats, and we characterized spatial relationships among sand layers, microbial mat annual laminae, and carbonate precipitation with X-ray Computed Tomography (XCT). XCT observations and measurements of annual biomass accumulation indicate that thin mm-scale sediment layers are sufficient to significantly reduce photosynthetic activity within the benthic mats. Taken together, the thickness and associated transmissivity of the Lake Fryxell ice cover exert a strong control on the potential for benthic mat photosynthetic activity through both the amount of photosynthetically active radiation reaching the lake bottom and the patterns of sand sedimentation that control light transmission into the benthic mats. Anticipated changes to the Lake Fryxell ice cover and those of other PICLs could accordingly affect the overall primary productivity of these polar desert ecosystems.

Microbial mat primary productivity and pore water microenvironments controlled by changing ice cover attributes in a perennially ice-covered lake of the McMurdo Dry Valleys, Antarctica

Description

Session Format: Oral

Presentation Date: 10/11/2026

Presentation Start Time: 02:00 PM

Presentation Room: CCC, 105

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