REDOX DYNAMICS AND COMMUNITY COMPOSITION OF HYPERSALINE LAKE MICROBIAL MAT COMMUNITIES, SAN SALVADOR ISLAND

Microbial mat communities exist in the hypersaline lakes present on The Bahamian island of San Salvador. Each constituent of the microbial mats is responsible for specific nutrient and chemical cycling processes in the consortium, and understanding how environmental parameters affect the mats is important in understanding each mat's metabolic processes. In this research study, hydrogen sulfide (H₂S) concentrations, oxygen (O₂) concentrations, and microbial community composition were measured within microbial mats of three hypersaline lakes during The University of Akron's Field Research on Bahamian Lakes – Exploring Records of Anthropogenic and Climate Change Research Experiences for Undergraduates (REU) Project the determine the extent of variation in chemical redox processes and microbial community composition. The three lakes studied, French Pond, Salt Pond, and Triangle Pond, were selected for their spatial distribution and potential for variation in environmental characteristics. Using microelectrode profiling, we found H₂S concentrations to be significantly (p<0.05) different in Triangle Pond, and no significant differences between French Pond and Salt Pond. Oxygen concentrations were significantly (p<0.05) different in French Pond, but no significant differences in O₂ concentrations were found between Triangle Pond and Salt Pond. To further determine if these differences were due to microbial community composition, we analyzed each layer of all lakes through polymerase chain reaction (PCR) and 16S rRNA gene sequencing. Close similarities between corresponding layers in each lake's mat communities were observed. Variation in specific environmental parameters, such as organic carbon content, total inorganic carbon, salinity, pH, and dissolved oxygen, may be responsible for the difference in the H₂S and O₂ concentrations between the lakes. This research indicates that although San Salvador Island may be an isolated island with similar geographic features, small-scale environmental variations in the lakes can result in microbial mat communities that are metabolically unique.