Impacts of Global Climate Change and Biodiversity on Aquatic Bacterial Ecosystem FunctionEPA Grant Number: F07E10860
Title: Impacts of Global Climate Change and Biodiversity on Aquatic Bacterial Ecosystem Function
Investigators: Adams, Heather Elizabeth
Institution: University of Michigan
EPA Project Officer: Michaud, Jayne
Project Period: January 1, 2007 through January 1, 2009
RFA: STAR Graduate Fellowships (2007) RFA Text | Recipients Lists
Research Category: Global Climate Change , Academic Fellowships , Fellowship - Aquatic Microbial Ecology
This dissertation research asks how the effects of climate change, such as increased temperature and nutrients, interact with community composition to control aquatic bacterial production and various ecosystem functions. Answering these questions will help resolve the actual mechanisms of interaction between bacterial diversity, environmental factors, and ecosystem function in terms of bacterial activity. This understanding will help us to predict how ecosystems will respond to impending changes in biodiversity and global climate change.
(1) How fast can microbial community assemblages shift during new environmental conditions? (2) How important are transfers of new microbial species from upstream communities? The corresponding hypothesis for these two questions is: Community compositional shifts occur at ecologically relevant time scales, and the transient bacterial communities have impacts on overall bacterial activity only during periods of intense environmental variation.
To determine the rate of species sorting in the community and if mass effects of incoming bacteria affect activity, experiments will consist of (1) a field transplant experiment using dialysis bags and (2) parallel laboratory incubations. Dialysis bags are available in a wide variety of pore sizes, which allow contained bacteria from one place and time to be exposed to different environments because substrates and nutrients can diffuse across the membrane. This technique can isolate the effect of transient terrestrial and upstream communities coming in at the lake inlet by keeping a community in place, or transplanting it to a different location and tracking the dynamics in situ.
It is predicted that bacteria moving downstream with carbon from their originating habitats will continue to be productive downstream when transplanted. However, bacteria from downstream will have depressed activity when moved upstream due to inability to process the incoming carbon. The results of the community transplant experiments will determine the importance of microbial diversity, which is likely to affect ecosystem function via nutrient use, growth efficiencies, and substrate decomposition.