Deep Sea Extreme Environments

Examining the interrelationships between microorganisms and the environments within which they exist is a basic goal of biogeochemistry. When such studies focus on the cycling of life in environments characterized by physiological extremes with respect to temperature, salinity, pH, etc., new insight can be obtained regarding the evolution of life on Earth and the ability of microorganisms to adapt to a variety of challenging conditions. The study of extreme environments is often referred to as "Astrobiology."

Our research in extreme environments examines a broad range of heterotrophic (sulfate, nitrate, iron and manganese reduction) and chemoautotrophic processes. We use traditional biogeochemical approaches and molecular biological and organic geochemical methods to quantify rates of processes, access microbial diversity and genetic potential, and to identify novel microorganisms with unique physiologies. Topography of the deep seafloor is similar to that in some terrestrial environments. The seafloor is characterized by mountains and canyons, plains and valleys, and is home to hypersaline lakes, mud volcanoes, and gas seeps and vents. The habitats associated with release of fluids derived from deep within the Earth to the seafloor and into the water column are extreme; they are characterized by varying temperatures, cold and hot (range 4 to 400 ºC), and authigenic minerals, like barite, iron sulfide, pyrite, phosphorites, and elemental sulfur, that are not normally present. Cold seeps, gas hydrates, brine pools, and microbial mats are but a few of the distinguishing features of these extreme environments. These deep sea habitats teem with life, and microorganisms form the base of the ecosystem food chain.

Our research reaches into various deep sea environments, but our primary focus is on the Gulf of Mexico and its cold seeps. We also explore the hydrothermal vents in Guaymas Basin in the Gulf of California.