SPECTRAL ARCHIVE AND REMOTE CHARACTERIZATION OF TERRESTRIAL MICROBIAL MATS IN THE FRYXELL BASIN OF TAYLOR VALLEY, ANTARCTICA

The ecology of the basins in the McMurdo Dry Valleys (MDV) of Antarctica have been primarily studied using ground-based measurements. Recent advances in remote sensing of the Transantarctic Mountains provide the capability to detect photosynthetic microbial communities from space. Our study explores the important role of remote sensing in studying these microbial assemblages.

We remotely distinguish microbial mats in the glacial meltwater streams of the Fryxell Basin by ground-truthing spectral imagery from the WorldView-2 (WV2) and WorldView-3 (WV3) satellites. A spectral database of microbial mat types, characterized based on mat color, was created with over 140 hyperspectral measurements acquired during the 2018-2019 field season using an ASD hyperspectral FieldSpec 4 spectrometer. We used these measurements to create multiple spectral libraries for each field site. The libraries consist of end members, which are spectra of specific microbial mat types, known to be present in WV2 and WV3 images based on field observations. We used a least-squares linear unmixing model with these field-derived end members to predict the abundance of microbial communities throughout the Fryxell Basin. An iterative unmixing algorithm was also used to validate our results and improve our end member selection. Results show the areal abundance of microbial mat present at each field location. We compared these results to percent coverage data obtained in the field to assess the accuracy of our model and correlate remote detection to biomass estimates.

Initial results include a spectral archive of all significant microbial mat types and their fundamental properties. Spectral libraries and the abundance of mat types present in the Relict Channel and Crescent, Bowles, McKnight, and Canada Streams were also produced. Work to correlate spectral signature to the presence and abundance of specific pigments is ongoing.

Remote study of these microbial organisms limits human impact in the Fryxell Basin and contributes to the preservation of these unique photosynthesizing communities. It also provides insight into temporal and spatial changes in ecosystem dynamics throughout the basin. The spectral library and methods of detection presented in this study are also crucial for detecting potential life on other Solar System bodies.