Project Summary

Microbial Observatory at Soap Lake

     This study focuses primarily on the biogeochemistry, biomass production by, and microbial diversity of anaerobic bacterial communities in Soap Lake, WA. Soap Lake is an excellent choice for a Microbial Observatory because it is microbially dominated, having no macrophytes, a well characterized community of eukaryotic algae and zooplankton, and limnological data spanning the last sixty years.  Soap Lake is an example of a modern depositional environment characterized by having very high concentrations of sodium, carbonate, bicarbonate, chloride, sulfate, and sulfide. It is extremely alkaline, with water column pH ranging from 9.2 to 10.2, and sediment pH ranging from 10.1 – 11.3. It is also permanently meromictic, having perhaps the longest maintained meromixis of any lake on earth (at least 2,000 years). Both the mixolimnion and monimolimnion have high sulfide concentrations, averaging 4 mM in the mixolimnion waters and sediments, and as high as 300 mM in the monimolimnion sediments. In spite of high salinity, alkalinity and high sulfide concentrations, the lake is highly productive, with an average productivity of 391 g C m-2 year. Productivity is affected both temporally and spatially, with apparent significant contribution by anoxygenic photosynthetic bacteria.  Additionally, rates of sulfate reduction are also very high, and exceed the rates seen at similar lakes (Mono Lake, CA, Big Soda Lake, NV and Lake Magadi, Kenya) by one to two orders of magnitude. Methanogenesis appears to be a relatively minor metabolism in Soap Lake, with rates an order of magnitude lower than that seen in similar lakes.

Currently there is very little is taxonomic or ecological data about the fungal and bacterial microorganisms in Soap Lake. We plan to use both culture and non-culture based methods to describe the diversity of the anaerobic microbial communities (phototrophs and chemotrophs), and the fungal communities. We will estimate rates of primary and secondary production to elucidate the significance of the anaerobic communities on total biomass production. Additional activity measurements, including rates of osmolyte metabolism, cellulose and chitin degradation, nitrogen fixation, sulfate reduction and methanogesis will be assessed, and correlated with rates of primary productivity. We propose to integrate the biochemical and microbiological data accumulated with (1) on-site reflectance spectra obtained with a portable spectrometer operating between 0.3 and 1.0 microns and (2) an analysis of Landsat images of Soap Lake as it appears during and between algal blooms. The “ground truth” microbial and chemical data will be used to produce an estimate of biomass before and during algal blooms. The ground spectrometer and orbital satellite multispectral imaging data will be used to help develop limit of detection estimates for a Virtual Planet Laboratory being developed by the Jet Propulsion Laboratory, California Institute of Technology. Biological measurements of primary and secondary productivity will support these data, allowing for a predictive model of biomass production to be generated not only for Soap Lake, but for other haloalkaline systems. This model can then be used to augment the data available for the search for biological systems on Mars and extra-solar terrestrial environments. This project includes plans for a summer course at Soap Lake targeted at teaching extremophile biology to undergraduate students, graduate students, and teachers from high schools, community colleges and 4-year primarily undergraduate institutions. Additionally, this project will likely lead to discovery of novel microorganisms useful in industry and biotechnology.