2022-2023 Science Planning Summary
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2022-2023 USAP Field Season
Project Detail

Project Title

Seasonal primary productivity and nitrogen cycling in photosynthetic mats, Lake Fryxell, McMurdo Dry Valleys

Lake Fryxell. Photo by Joe Mastroianni, courtesy of the NSF/USAP Photo Library. Creative Commons CC BY-NC-ND 4.0
B-047-M Research Location(s): Lake Fryxell


Event Number:
NSF / OPP Award 1937748

Program Director:
Dr. Rebecca Gast

ASC POC/Implementer:
Judy Shiple / Jenny Cunningham

Principal Investigator(s)

Dr. Dawn Yvonne Sumner
University of California Davis
Geology Department


Supporting Stations: McMurdo Station
Research Locations: Lake Fryxell


This project will evaluate the effect of light and microbial mat activity on biogeochemical cycling in winter and summer in Lake Fryxell, McMurdo Dry Valleys. The team will specifically evaluate the role of light on microbial mat oxygen production and nitrogen cycling in the system. Divers will deploy microsensors in and immediately above the benthic mats in different months to measure small scale changes in water chemistry with differing light exposure. Mats will also be subsampled to evaluate changes in microbial gene expression in differing conditions. The research will provide important new insights into the winter behaviors of microbes in mats and how biotic, abiotic, and environmental components of ecosystems interact within specific processes (e.g., redox and nitrogen cycling to affect the entire McMurdo Dry Valley ecosystem). Results will be used to construct a biogeochemical model for seasonal biomass generation and phenotypic changes in the system.

Field Season Overview

This is the first of two field seasons. Five participants will deploy from December through early February, residing for five to six weeks at Lake Fryxell fixed camp. The team will conduct under-ice diving at one dive site to study microbial mats in the lake. They will collect water and mat samples and deploy biogeochemical monitoring equipment and shades at four water depths near the mat surface between 6 and 10 m depth. The installed instruments and shades will remain in place over winter between deployment seasons, and all installations will be retrieved during the second season.

Deploying Team Members

  • Ian Hawes
  • Sarah King
  • Dawn Sumner (PI)