Title page for ETD etd-08222007-152708


Type of Document Master's Thesis
Author Gray, Travis Michael
Author's Email Address tgray@vt.edu
URN etd-08222007-152708
Title Linking Heterotrophic Metabolism and Nutrient Uptake in Headwater Streams
Degree Master of Science
Department Biology
Advisory Committee
Advisor Name Title
Valett, H. Maurice Committee Chair
Benfield, Ernest Fredrick Committee Member
Daniels, Walter Lee Committee Member
Keywords
  • allochthonous organic matter
  • ecosystem
  • litter breakdown
  • nitrate
  • nutrient spiraling
  • nutrient demand
Date of Defense 2007-04-25
Availability unrestricted
Abstract
Autotrophs and heterotrophs differ in their demand, acquisition and use of materials, but fundamentally nutrient demand is inherently linked to metabolism based on the stoichiometry of biochemical reactions. The differences between these two groups of organisms confound straightforward regression approaches to quantifying the relationship between nutrient demand and metabolism at an ecosystem level. We address how nutrient demand in headwater streams changes with shifts in organic matter supply and associated microbial activity by investigating these relationships in the predominantly heterotrophic conditions of a southern Appalachian stream. We measured litter input, organic matter standing crops, litter respiration rates and nitrate demand several times during the course of decomposition. There was a strong relationship between leaf standing crop and nitrate uptake efficiency across dates with maximal efficiency occurring when litter standing crops were highest. There was also an increase in nitrogen (N) uptake rate relative to respiration rates as breakdown progressed, which appears to be due to a shift in nutrient supply from the substrate to the water column associated with the depletion of labile, high quality organic matter in the substrate. It is our contention that streams establish a gradient of resource supply from particulate to dissolved sources that coincides with the movement of materials from terrestrial to marine systems.
Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  Thesis.pdf 349.47 Kb 00:01:37 00:00:49 00:00:43 00:00:21 00:00:01

Browse All Available ETDs by ( Author | Department )

dla home
etds imagebase journals news ereserve special collections
virgnia tech home contact dla university libraries

If you have questions or technical problems, please Contact DLA.