HR: 1330h
AN: NB33I-12    [Abstracts]
TI: Relative Contributions of Leaf-associated Microorganisms to Leaf Litter Breakdown in a Nutrient-enriched Headwater Stream
AU: * Tant, C J
EM: ctant@uga.edu
AF: Institute of Ecology, University of Georgia , Athens, GA 30602
AU: Rosemond, A D
EM: rosemond@uga.edu
AF: Institute of Ecology, University of Georgia , Athens, GA 30602
AU: Taylor, N
EM: ntaylor@uga.edu
AF: Institute of Ecology, University of Georgia , Athens, GA 30602
AU: Conners, D E
EM: dconners@uga.edu
AF: Institute of Ecology, University of Georgia , Athens, GA 30602
AU: Suberkropp, K
EM: ksuberkp@biology.as.ua.edu
AF: Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487
AB: Litter decomposition in streams occurs as a function of microbial and invertebrate processing, as well as abiotic factors. Abiotic factors, such as streamwater nutrient concentrations, may change the relative importance of groups of microorganisms, as well as invertebrates, to leaf breakdown. We plan to quantify the relative contributions of bacteria, fungi, and invertebrate processing on decaying leaves in a reference and treatment stream (experimentally enriched with N & P for 4.5 yrs) at the Coweeta Long Term Ecological Research site in North Carolina, USA. Leaf packs of maple or rhododendron leaves were periodically retrieved to determine decay rates. Microbial activity was measured as respiration, fungal biomass was determined by measuring ergosterol concentration, and bacterial biomass was determined by epifluorescence microscopy. Breakdown rates were dramatically faster in the nutrient enriched stream than the reference stream, associated with greater microbial activity and presumably, invertebrate feeding. Based on whole-system response by microorganisms, we predict that nutrient enrichment will lead to greater contributions of fungi, relative to bacteria, to leaf breakdown. Our results show that enrichment can fundamentally alter the rate of organic matter breakdown in streams, and will test whether enrichment also changes the relative roles of groups of organisms contributing to breakdown processes.
DE: 4815 Ecosystems, structure and dynamics
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly