¹Department of Ecology, Evolution and Behavior, University of Minnesota, St Paul, MN, USA

Correspondence: EK Hall, Department of Freshwater Ecology, University of Vienna, Althanstr. 14, A-1090 Vienna, Austria. E-mail: hall0506@umn.edu

²Current address: Department of Freshwater Ecology, University of Vienna, Vienna, Austria

Received 26 November 2007; Accepted 17 December 2007; Published online 7 February 2008.

Abstract

We examine how heterotrophic bacterioplankton communities respond to temperature by mathematically defining two thermally adapted species and showing how changes in environmental temperature affect competitive outcome in a two-resource environment. We did this by adding temperature dependence to both the respiration and uptake terms of a two species, two-resource model rooted in Droop kinetics. We used published literature values and results of our own work with experimental microcosms to parameterize the model and to quantitatively and qualitatively define relationships between temperature and bacterioplankton physiology. Using a graphical resource competition framework, we show how physiological adaptation to temperature can allow organisms to be more, or less, competitive for limiting resources across a thermal gradient (2–34 °C). Our results suggest that the effect of temperature on bacterial community composition, and therefore bacterially mediated biogeochemical processes, depends on the available resource pool in a given system. In addition, our results suggest that the often unclear relationship between temperature and bacterial metabolism, as reported in the literature, can be understood by allowing for changes in the relative contribution of thermally adapted populations to community metabolism.