USAP-DC

Part I: Non-technical summary: This project focuses on understanding annual changes in microbial life that grows on the bottom of Lake Fryxell, Antarctica. Because of its polar latitude, photosynthesis can only occur during the summer months. During summer, photosynthetic bacteria supply communities with energy and oxygen. However, it is unknown how the microbes behave in the dark winter, when observations are not possible. This project will install environmental monitors and light-blocking shades over parts of these communities. The shades will extend winter conditions into the spring to allow researchers to characterize the winter behavior of the microbial communities. Researchers will measure changes in the water chemistry due to microbial activities when the shades are removed and the mats first receive light. Results are expected to provide insights into how organisms interact with and change their environments. The project includes training of graduate students and early career scientists in fieldwork, including scientific ice diving techniques. In addition, the members of the project team will develop a web-based “Guide to Thrive”, which will compile field tips ranging from basic gear use to advanced environmental protection techniques. This will be a valuable resource for group leaders ranging from undergraduate teaching assistants to Antarctic expedition leaders to lead well-planned and tailored field expeditions. Part II: Technical summary: The research team will measure seasonal metabolic and biogeochemical changes in benthic mats using differential gene expression and geochemical gradients. They will identify seasonal phenotypic differences in microbial communities and ecosystem effects induced by spring oxygen production. To do so, researchers will install environmental sensors and opaque shades over mats at three depths in the lake. The following spring, shaded and unshaded mats will be sampled. The shades will then be removed, and changes in pore water O2, H2S, pH, and redox will be measured using microelectrodes. Mats will also be sampled for transcriptomic gene expression analyses at intervals guided by geochemical changes. Pore water will be sampled for nutrient analyses. Field research will be supplemented with laboratory experiments to refine field techniques, gene expression data analysis, and integration of results into a seasonal model of productivity and nitrogen cycling in Lake Fryxell. Results will provide insights into several key priorities for NSF, including how biotic, abiotic and environmental components of the benthic mats interact to affect Antarctic lakes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Person	Role
Sumner, Dawn	Investigator and contact
Mackey, Tyler	Investigator

Antarctic Integrated System Science	Award # 1937748
Antarctic Organisms and Ecosystems	Award # 1937748

USAP-1937748_1

Deployment	Type
Lake Fryxell Diving - Planned	field camp

Data_Management_Plan_v2.pdf

Repository	Title (link)	Format(s)	Status
USAP-DC	Lake Fryxell 2022-2023 benthic microbial mat thickness and number of laminae	Comma-Separated Values (CSV)	exists

1. Clance, J., Mackey, T., & Juarez Rivera, M. (2022). Episodic carbonate precipitation in perennially ice-covered Lake Fryxell, Antarctica. (doi:10.1002/essoar.10512823.1)
2. Juarez Rivera, M., Mackey, T. J., Hawes, I., & Sumner, D. Y. (2025). Morphology and Distribution of Bubble‐Supported Microbial Mats From Ice‐Covered Antarctic Lakes. Journal of Geophysical Research: Biogeosciences, 130(3). Portico. (doi:10.1029/2024jg008516)
3. Powell, T., D. Y. Sumner, A. D. Jungblut, I. Hawes, T. Mackey, C. Grettenberger, 2024. Metagenome-assembled bacterial genomes from benthic microbial mats in ice-covered Lake Vanda, Antarctica. Microbiology Resource Announcements, 13(5):e0125023. (doi:10.1128/mra.01250-23 )
4. Lumian, Jessica E., Dawn Y. Sumner, Christen L. Grettenberger, Anne D. Jungblut, Luiz Irber, Tessa Pierce-Ward, and C. Titus Brown, 2024. Biogeographic distribution of five Antarctic Cyanobacteria using large-scale k-mer searching with sourmash branchwater. Frontiers in Microbiology 15:1328083. (doi:10.3389/fmicb.2024.1328083)
5. Lumian, Jessica E., Christen L. Grettenberger, Anne D. Jungblut, Tyler J. Mackey, Ian Hawes, Eduardo Alatorre-Acevedo, and Dawn Y. Sumner, 2024. Genomic profiles of four novel cyanobacteria MAGs from Lake Vanda, Antarctica: insights into photosynthesis, cold tolerance, and the circadian clock. Frontiers in Microbiology, Research Topic: Exploring Microbial Mat Communities in Extreme Environments, v. 14. (doi:10.3389/fmicb.2023.1330602)
6. Salley, Sydney, Ph.D. 2024. Benthic Microbial Mat Adaptations to Nutrient Scarcity and Nutrient Cycling Dynamics in Oligotrophic, Perennially Ice-covered Lake Vanda and Lake Fryxell in the McMurdo Dry Valleys, Antarctica. Ph.D. Dissertation, University of California, Davis
7. Marcello, Kaylah, Ph.D. 2025. Unraveling the Genomic and Adaptive Strategies of Antarctic Cyanobacteria: A Bioinformatic Analysis of Survival Mechanisms in Extreme Cold Environments Ph.D. Dissertation, University of California, Davis
8. Levett, Holly. Sand, Ice, and X-rays: Developing XCT Methods for Frozen Samples and Refining Siliciclastic Facies Models for Perennially Ice-Covered Lakes, Utilizing Cores From Lake Fryxell, McMurdo Dry Valleys, Antarctica. M.S. Thesis, University of New Mexico