Department of Microbiology and Immunology
Montana State University
Melody Lindsay is a 5th year Ph. D. candidate and a NASA Earth and Space Science Fellow in Dr. Eric Boyd’s geobiology lab in the Department of Microbiology and Immunology at Montana State University. Her thesis work focuses on studying the distribution and activities of extremophiles in order to understand the adaptations that facilitate life under extreme conditions. Her primary thesis project is directed at identifying the sources and distribution of geological hydrogen, the influence this hydrogen has on chemosynthetic thermophiles and on hydrogen-supported microbial communities in Yellowstone National Park hot springs. She has spent the last four years also working on projects investigating microbialites in Great Salt Lake. She is most grateful for the Friends of Great Salt Lake Doyle Stephens Scholarship, which has supported her research project that is aimed at investigating the relationships between changing salinity, microbialite primary production, and secondary consumption in GSL.
Title: Effects of Changing Salinity on Microbialite-Associated Primary Producers and Secondary Consumers in Great Salt Lake
Thursday, May 11th, 11:20 AM
Abstract: Primary producers serve as the base of all ecosystems. In Great Salt Lake (GSL), photosynthetic cyanobacteria and algae associated with microbialite structures, which cover ~20% of the lake bottom, contribute a significant amount of the primary production to the ecosystem. However, these phototrophs are subject to the changing conditions of the lake, including varying levels of salinity. We investigated the effects of changing salinity on the primary productivity and community composition of microbialites of GSL, as well as how these changes affect the fecundity of the secondary consumer species, Artemia franciscana (brine shrimp). Using a microcosm approach, we incubated microbialite samples at salinities ranging from 8.0% to 30%. Microcosms were inoculated with a known number of Artemia cysts and were incubated, and rates of primary production (CO2-fixation) were measured after letting the microcosms incubate for 8 weeks. Microbial community composition and abundance and hatch and survival rates of Artemia were assessed weekly. Rates of primary productivity in microbialite communities were significantly lower at salinities over 20%, with the highest rate of CO2-fixation measured at 10% salinity. The hatch rate of Artemia individuals was significantly decreased at salinities greater than 15%, but adult Artemia persisted at salinities of up to 20%. These results reveal a significant negative impact of salinities over 20% on the productivity of the microbialite communities, and also on the hatch and survival rates of Artemia franciscana. Shifts in the composition and abundance of microbialite microbial communities that may be responsible for the overall decrease in the productivity of microbialites will be presented.