Bio Sci Seminar - Trista Vick-Majors

 

Trista Vick-Majors, PhD

Assistant Professor, Biological Sciences

Michigan Technological University

Presentaiton Title: Physiochemical and physiological linkages in Antarctic aquatic microbial systems

Abstract: Ice cover is fundamental to the seasonal cycles of most of the world's lakes, and some high latitude lakes remain ice-covered year-round. Ice cover limits atmospheric exchange and, depending on ice thickness, light penetration, with cascading effects on aquatic biogeochemical processes. Ice-covered Antarctic lakes, which host microbially dominated ecosystems, serve as natural laboratories for biogeochmical studies under ice. The McMurdo Dry Valley (MCM) lakes, with relatively think, perennial, ice-covers (~3-5 m), recieve solar radiation and support phytoplankton-based food webs during the austral summer, but are subjected to continual darkness during the austral winter. Organisms must rely on non-photosynthetic sources of carbon and energy to survive the winter. Ecological network models showed that metabolic flexibility is key to ecosystem function in these otherwise physiochemically stable lakes. In contrast, Subglacial Lake Whillans (SLW) lies in permanent darkness under 800 m of ice. SLW is a hydrologically active (subject to fill-drain cycles), freshwater, oxic lake located beneath the surface of the West antarctic Ice Sheet in an area that was last inundated by seawater during the Pleistocene. Energetic constraints imposed by lake geochemistry favor chemoautotrophic metabolism over heterotrophic organic carbon oxidation, leading to long heterotrophic doubling times, while geochemical shifts mediated by fill-drain cycles favor heterotrophy. These data, combined with data on microbial community composition, showed that linkages between metabolic activity and hydrology are important in supporting nutrient recycling in SLW. Physiological and metabolic flexibility are key to maintaining ecosystem function in the ice covered MCM lakes and in SLW during periods of physiochemical change. Recently, a second subglacial lake (Subglacial Lake Mercer, ~1200 m thick ice cover) was accessed, providing clues to the diversity of environments present under Antarctic Ice.

Thursday, May 2 at 3:00 pm to 4:00 pm

Fisher Hall, 129
1400 Townsend Drive, Houghton, MI 49931

Event Type

Academics, Lectures/Seminars

Target Audience

Students, Graduate, Undergraduate, Faculty/Staff, Postdocs

Website

http://www.mtu.edu/biological

Subscribing Departments ?
Biological Sciences
Host ?

Biological Sciences

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