USAP-DC

Cryoconite holes are pockets of life completely encased in otherwise barren glacial ice. These pockets of life form when dust blown onto the ice melts a small, largely isolated hole that can function as its own tiny ecosystem. This dust can contain microorganisms such as bacteria, algae, or microscopic animals. The microorganisms within the hole interact and carry out functions typical of a larger ecosystem, such as a forest. Cryoconite holes are especially important in extreme cold environments such as the Antarctic Dry Valleys, where they function as repositories of life. Because cryoconite holes are mostly enclosed and persist for years, they can be tracked over time to test fundamental scientific questions about how communities of interacting organisms develop to become fully functioning ecosystems. This project will sample existing and experimentally created cryoconite holes to understand how these ecosystems develop and to what degree random processes (such as which organisms get there first) affect the final community composition and functioning. The results will not only improve our understanding of how microbial communities assemble and affect the functioning of microecosystems such as cryoconite holes, but also how the processes of community assembly affect functioning of larger ecosystems, such as forests. A better understanding of community establishment, development, and response to abiotic factors are essential to forecasting ecological responses to environmental change.

It is essential to unravel the links between community assembly, biodiversity, and nutrient cycling across numerous ecosystems because these are critical factors determining ecological responses to environmental change. The unique, largely isolated nature of cryoconite holes provides an experimental system that will advance fundamental understanding of the processes (e.g., stochastic dynamics such as dispersal limitation, assembly order, and ecological drift) driving community assembly. This project will use a field sampling campaign and a number of manipulative experiments to test a hypothesis that unites theory in community and ecosystem ecology: the degree to which stochastic processes guide microbial community assembly and affects regional patterns in biodiversity and ecosystem processes. Cryoconite holes will be sampled to compare community composition, environmental factors, and ecosystem functioning between hydrologically connected and isolated holes. New cryoconite holes will also be constructed and monitored over the course of two growing seasons to specifically alter assembly order and community size, thereby pairing a unique manipulative experiment with field surveys to address questions with relevance to the Antarctic and beyond. Amplicon sequencing, metagenomics, microscopy, sensitive environmental chemistry methods, and photosynthesis and respiration measurements will be used to test a series of sub-hypotheses that relate stochasticity to patterns in regional biodiversity, heterogeneity in environmental factors, and ecosystem processes.

Person	Role
Schmidt, Steven	Investigator and contact
Cawley, Kaelin	Co-Investigator
Fountain, Andrew	Co-Investigator
Sommers, Pacifica	Researcher

Antarctic Organisms and Ecosystems

Award # 1443578

USAP-1443578_1

Deployment	Type
Sampling and experiments on glaciers in Taylor Valley	field camp

Antarctic_project_DMP_updated20191101.pdf

Repository	Title (link)	Format(s)	Status
NCBI GenBank	Genomes of Antarctic ssDNA viruses (GenBank accession numbers MN311489-MN311492 and MN328267-MN328291)	None	no link
GitHub	Metadata from samples (in the process of submitting to EDI; will update with DOI once completed)	None	exists
NCBI GenBank	16S and 18S amplicon sequencing of Antarctic cryoconite holes	None	exists
NCBI GenBank	Soil microbial communities of a mountain landscape, McMurdo Dry Valleys, Antarctica	None	exists
NCBI GenBank	Microbial species-area relationships in Antarctic cryoconite holes	None	exists

1. Sommers, P.; Darcy, J. L.; Gendron, E. M. S.; Stanish, L. F.; Bagshaw, E. A.; Porazinska, D. L.; Schmidt, S. K., Diversity patterns of microbial eukaryotes mirror those of bacteria in Antarctic cryoconite holes. FEMS Microbiol. Ecol. 2018, 94, (1). (doi:10.1093/femsec/fix167)
2. Sommers, P.; Darcy, J. L.; Porazinska, D. L.; Gendron, E. M. S.; Fountain, A. G.; Zamora, F.; Vincent, K.; Cawley, K. M.; Solon, A. J.; Vimercati, L.; Ryder, J.; Schmidt, S. K., Comparison of Microbial Communities in the Sediments and Water Columns of Frozen Cryoconite Holes in the McMurdo Dry Valleys, Antarctica. Front. Microbiol. 2019, 10, 65. (doi:10.3389/fmicb.2019.00065)
3. Darcy, J. L.; Gendron, E. M. S.; Sommers, P.; Porazinska, D. L.; Schmidt, S. K., Island Biogeography of Cryoconite Hole Bacteria in Antarctica's Taylor Valley and Around the World. Frontiers in Ecology and Evolution 2018, 6. (doi:10.3389/fevo.2018.00180)
4. Sommers, P.; Fontenele, R. S.; Kringen, T.; Kraberger, S.; Porazinska, D. L.; Darcy, J. L.; Schmidt, S. K.; Varsani, A., Single-stranded DNA viruses in Antarctic cryoconite holes. In press, Viruses.
5. Sommers, P., Porazinska, D. L., Darcy, J. L., Zamora, F., Fountain, A. G., & Schmidt, S. K. (2019). Experimental cryoconite holes as mesocosms for studying community ecology. Polar Biology, 42(11), 1973-1984. (doi:10.1007/s00300-019-02572-7)
6. Sommers, P.; Fontenele, R. S.; Kringen, T.; Kraberger, S.; Porazinska, D. L.; Darcy, J. L.; Schmidt, S. K.; Varsani, A., Single-stranded DNA viruses in Antarctic cryoconite holes. In press, Viruses. (doi:10.3390/v11111022)
7. Darcy, J. L., Schmidt, S. K., Knelman, J. E., Cleveland, C. C., Castle, S. C., & Nemergut, D. R. (2018). Phosphorus, not nitrogen, limits plants and microbial primary producers following glacial retreat. Science Advances, 4(5), eaaq0942. (doi:10.1126/sciadv.aaq0942)
8. Darcy, J. L., King, A. J., Gendron, E. M. S., & Schmidt, S. K. (2017). Spatial autocorrelation of microbial communities atop a debris-covered glacier is evidence of a supraglacial chronosequence. FEMS Microbiology Ecology, 93(8). (doi:10.1093/femsec/fix095)
9. Schmidt, S.K., B.W. Johnson, A.J. Solon, P. Sommers, J.L. Darcy, K. Vincent, L. Vimercati, A.G. Fountain, D. Porazinska (2022). Microbial biogeochemistry and phosphorus limitation in cryoconite holes on glaciers across the Taylor Valley, McMurdo Dry Valleys, Antarctica. Biogeochemistry
10. Solon, A.J., C. Mastrangelo, P. Sommers, L. Vimercati, D.L Porazinska, J.L. Darcy, E.M.S. Gendron, S.K. Schmidt (2021). Gullies and Moraines Are Islands of Biodiversity in an Arid, Mountain Landscape, Asgard Range, Antarctica. Frontiers Microbiology (doi:10.3389/fmicb.2021.654135)
11. Solon, A.J., Mastrangelo, C., Tubman, A., Vimercati, L., Porazinska, Sommers, P., and Schmidt S.K. (2022). Nutrient limitation of high-elevation photoautotrophs varies among lake basins in Taylor Valley, Antarctica. Biogeosciences.
12. Zawierucha, K., Porazinska, D.L., Ficetola, G.F., Ambrosini, R., Baccolo, G., Buda, J., Ceballos, J.L., Devetter, M., Dial, R., Franzetti, A., Fuglewicz, U., Gielly, L., Łokas, E., Janko, K., Novotna Jaromerska, T., Kościński, A., Kozłowska, A., Ono, M., Parnikoza, I., Pittino, F., Poniecka, E., Sommers, P., Schmidt, S.K., Shain, D., Sikorska, S., Uetake, J. and Takeuchi, N. (2020). A hole in the nematosphere: tardigrades and rotifers dominate the cryoconite hole environment, whereas nematodes are missing. Journal of Zoology, 313(1), 18-36 (doi:10.1111/jzo.12832)
13. Sommers P., A. Chatterjee, A. Varsani, G. Trubl (2021). Integrating viral metagenomics into an ecological framework. Annual Reviews of Virology. 8 6.1. (doi:10.1146/annurev-virology-010421-053015)
14. Schmidt, S. K., Johnson, B. W., Solon, A. J., Sommers, P., Darcy, J. L., Vincent, K., Vimercati, L., Fountain, A. G., & Porazinska, D. L. (2022). Microbial biogeochemistry and phosphorus limitation in cryoconite holes on glaciers across the Taylor Valley, McMurdo Dry Valleys, Antarctica. Biogeochemistry. https://doi.org/10.1007/s10533-022-00900-4 (doi:10.1007/s10533-022-00900-4)
15. McQueen, J. P., Gattoni, K., Gendron, E. M. S., Schmidt, S. K., Sommers, P., & Porazinska, D. L. (2022). Host identity is the dominant factor in the assembly of nematode and tardigrade gut microbiomes in Antarctic Dry Valley streams. Scientific Reports, 12(1). (doi:10.1038/s41598-022-24206-5)
16. Sommers, P., Porazinska, D. L., Darcy, J. L., Gendron, E. M. S., Vimercati, L., Solon, A. J., & Schmidt, S. K. (2020). Microbial Species–Area Relationships in Antarctic Cryoconite Holes Depend on Productivity. Microorganisms, 8(11), 1747. (doi:10.3390/microorganisms8111747)
17. Schmidt, S. K., Vimercati, L., Solon, A. J., Robinson, J. N., Bueno de Mesquita, C. P., & Johnson, B. W. (2024). Evidence for rapid ecosystem retrogression along a post-glacial chronosequence in Antarctica. Polar Biology. (doi:10.1007/s00300-024-03279-0)