MICROBIAL STRATIFICATION AND INFERRED MICROBIALLY CATALYZED PROCESSES ALONG A DEEP-SEA HYPERSALINE CHEMOCLINE

• Main Author: Hyde, Andrew
• Other Authors: College of Arts and Sciences, Department of Marine Sciences, Alperin, Marc, Teske, Andreas, Arnosti, Carol
• Format: Master Thesis
• Language: English
• Published: University of North Carolina at Chapel Hill 2018
• Subjects: Sulfur metabolism; Microbiology; Environmental microbiology; Hypersaline; Marine microbiology; Biogeochemistry; Orca
• Online Access: https://doi.org/10.17615/8fqd-nz07; https://cdr.lib.unc.edu/downloads/pz50gx179?file=thumbnail; https://cdr.lib.unc.edu/downloads/pz50gx179

The Gulf of Mexico contains the world’s largest anoxic hypersaline seafloor basin, Orca Basin. The water contained in this 400 km2 bathymetric depression is roughly eight times as saline as the overlying seawater. The resulting density contrast prevents the 200 m deep brine layer from mixing with seawater, creating an interface that traps particles of organic matter falling through the water column. The concentrated organic matter at the interface is hypothesized to host a thriving bacterial community that has yet to be characterized. Here, I present the results of the first bacterial community analysis by high-throughput sequencing ever conducted on the interface and brine pool of Orca Basin. I discuss how the bacterial community changes along a 550 m vertical transect with regards to oxygen, salinity, and organic matter gradients. Finally, a comparison of the geochemical and bacterial composition of Orca Basin to brine pools in the Mediterranean and Red Seas reveals the uniqueness of Orca Basin in a global context. This research adds to our current knowledge of biodiversity in global hypersaline habitats and has implications for our understanding of sulfur and carbon cycling in extreme environments Master of Science