Hyperspectral studies of hypersaline ecosystems

Abstract

We have investigated the correlation of remotely-sensed infrared spectral information with in situ field measurements and sampling to monitor ecosystem health, salinity, and population distributions of specific microbial communities occupying the salt ponds of southern San Francisco Bay. Approximately 61 km 2 of these salt evaporation ponds are scheduled to be restored to natural habitat over the next few decades as part of a historic remediation project. Significant cost reduction may be achieved through the use of a remote infrared monitoring approach in place of extensive sampling expeditions by field teams. Unique spectral signatures of microbial populations sensitive to salinity and other chemical concentrations provide the key to this method. The Airborne Visible and InfraRed Imaging Spectrometer (AVIRIS) instrument operated by the Jet Propulsion Laboratory (JPL) has created a ten-year archive of spectral information concerning these ponds which can be used to establish a baseline for comparison. We report here on in situ field sampling of microbial populations, including spectral measurements, and our results using these spectra to train a supervised classification algorithm (the US Geological Survey Tetracorder Algorithm) to identify microbial populations and physical parameters from an AVIRIS scene. Future measurements and data from satellite-based sensors may prove vital in monitoring the restoration process. High spectral resolution measurements from AVIRIS will be used to determine the efficacy of similar approaches using existing multispectral spaceborne sensors as well as to provide a reference for future, AVIRIS-class spacecraft as a surrogate for expensive ground surveys.