COS 108-3 - To flee or not to flee: The microbial response to changing temperature in a stream environment

Thursday, August 11, 2011: 2:10 PM
6A, Austin Convention Center
Ed K. Hall, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO and Tom J. Battin, Department of Limnology, University of Vienna, Vienna, Austria

The biogeochemical function of stream ecosystems is driven in large part by microbial biofilms inhabiting the highly reactive interstitial zone. Shifts in stream temperature affect biogeochemical processes but it is unclear to what extent these changes reflect dynamics of the microbial communities that drive these processes. We used natural alpine stream sediment and flow-through bioreactors to grow interstitial biofilms on beech litter leachate that differed in Phosphorus (P) content.Temperature for all bioreactors alternated between 5°C and 15°C on a regular cycle over 80 days. 


After each temperature shift we observed increased fluxes of both live and dead cells in the effluent of all reactors. The quantity of cells and timing of the pulse of cells in the effluent differed between treatments. Within the bioreactors, biofilms from the high P treatment had higher biomass nitrogen:P than biofilms from the low P treatment. In addition, treatments differed in microbial community composition between reactors as well as the distribution of communities within a given reactor. We use these results to discuss how limiting resources can affect the strategy microorganisms employ to deal with changing temperature and the implications this has for biogeochemical cycling.

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