Microbial Observatories: Anhydrophilic, Halotolerant Microbial Mats of San Salvador Island, Bahamas

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

Drs. Hans Paerl and Timothy Steppe (University of North Carolina at Chapel Hill), Alan Decho (University of South Carolina at Columbia), James Pinckney (Texas A & M University) are examining the community structure and function of highly-diverse microbial mats located in lakes on San Salvador Island, Bahamas. Because water evaporation exceeds rain precipitation on San Salvador, lakewater salinity can reach up to five times that of normal seawater. Interannual and seasonal variability in rainfall causes lake-levels and salinities to fluctuate greatly. Consequently, the microbial mats, which cover extensive portions of the lake bottoms and control the lakes' ecology, are subjected to prolonged periods of harsh, potentially lethal constraints such as desiccation, intense solar radiation, and high temperatures. Yet, they manage to grow and survive under some of the most extreme conditions on the planet. The objective of this study is to assess the influence water availability has on the structural diversification, community composition, production, and carbon sequestration in microbial mats over a five-year period. A particular emphasis will be placed on culturing and characterizing novel organisms that are adapted to water-stressed environments. State of the art molecular biological, polymer chemistry, physiological, and microbiological techniques will be employed to accomplish the research goals. Water is indispensable for life. The proposed work addresses a fundamental mechanism that is essential to all life, the ability to conserve water and balance ions. Understanding and characterizing water-stressed microbial communities may provide information crucial for understanding key controls of life processes on other planets and moons where water may exist. Anhydrophilic communities exist under 'feast or famine' conditions with regard to water availability. Rainfall on San Salvador is episodic and largely confined to major storms, including hurricanes to which the island is often subjected. Monitoring the physiological responses of pristine anhydrophilic communities over time and under different hydrologic conditions will provide information necessary to understanding how long and short term climatic oscillations (including a predicted 10 to 40 year period of elevated hurricane activity) impact critical life-sustaining processes. Culturing individual populations will provide specific information for understanding the biology of anhydrophilic life forms that may be exploited for industrial or medical purposes.