Project Title

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

Summary

Event Number:
B-047-M
NSF / OPP Award 1937748

Program Director:
Dr. Rebecca Gast

ASC POC/Implementer:
Ryan Steiner / Jenny Cunningham

Principal Investigator(s)

Dr. Dawn Yvonne Sumner
dawninantarctica.23@gmail.com
University of California Davis
Geology Department
Davis, California

Location

Supporting Stations: McMurdo Station
Research Locations: Lake Fryxell

Description

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

Five participants, including one Antarctica New Zealand collaborator, will deploy from December through late January, residing for five to six weeks at Lake Fryxell fixed camp in Taylor Valley. The team will conduct under-ice diving from a heated Polarhaven positioned at one dive site on the lake ice to study microbial mats on the lake floor. They will collect water and mat samples and deploy biogeochemical monitoring equipment and shades at three 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 2025-26 season.

Deploying Team Members