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Title: Drivers of nitrogen transfer in stream food webs across continents

Studies of trophic-level material and energy transfers are central to ecology. The use of isotopic tracers has now made it possible to measure trophic transfer efficiencies of important nutrients and to better understand how these materials move through food webs. We analyzed data from thirteen 15N-ammonium tracer addition experiments to quantify N transfer from basal resources to animals in headwater streams with varying physical, chemical, and biological features. N transfer efficiencies from primary uptake compartments (PUCs; heterotrophic microorganisms and primary producers) to primary consumers was lower (mean: 11.5%, range: <1%-43%) than N transfer efficiencies from primary consumers to predators (mean: 80%, range: 5%- >100%). Total N transferred (as a rate) was greater in streams with open compared to closed canopies and overall N transfer efficiency generally followed a similar pattern, although was not statistically significant. We used principal component analysis to condense a suite of site characteristics into two environmental components. Total N uptake rates among trophic levels were best predicted by the component that was correlated with latitude, DIN:SRP, GPP:ER, and % canopy cover. N transfer efficiency did not respond consistently to environmental variables. Here, our results suggest that canopy cover influences N movement through stream food webs becausemore » light availability and primary production facilitate N transfer to higher trophic levels.« less
 [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] ; ORCiD logo [13] ;  [14] ; ORCiD logo [15] ;  [16] ;  [17] ;  [18] ;  [19] ;  [20] more »;  [21] ;  [22] ;  [23] ;  [24] ;  [25] « less
  1. Michigan State Univ., East Lansing, MI (United States)
  2. Southern Illinois Univ., Carbondale, IL (United States)
  3. Univ. of Wisconsin, Madison, WI (United States)
  4. Cornell Univ., Ithaca, NY (United States)
  5. Michigan State Univ., Hickory Corners, MI (United States)
  6. Pacific Northwest National Lab. (PNNL), Corvallis, OR (United States)
  7. Cary Institute of Ecosystem Studies, Millbrook, NY (United States)
  8. Oregon State Univ., Corvallis, OR (United States)
  9. Univ. of Vermont, Burlington, VT (United States)
  10. Univ. of New Mexico, Albuquerque, NM (United States)
  11. Florida Intl Univ., Miami, FL (United States)
  12. Kansas State Univ., Manhattan, KS (United States)
  13. Univ. of Wyoming, Laramie, WY (United States)
  14. Univ. of Victoria, Victoria (Canada)
  15. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  16. Centre d'Estudis Avancats de Blanes (CEAB-CSIC), Blanes (Spain)
  17. Univ. of New Hampshire, Durham, NH (United States)
  18. Murray State Univ., Murray, KY (United States)
  19. Minnesota Dept. of Natural Resources, St. Paul, MN (United States)
  20. Aarhus Univ., Aarhus (Denmark)
  21. Univ. of Auckland, Auckland (New Zealand)
  22. Univ. of Notre Dame, Notre Dame, IN (United States)
  23. Univ. of Nebraska, Lincoln, NE (United States)
  24. Univ. of the Basque Country, Bilbao (Spain)
  25. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 98; Journal Issue: 12; Journal ID: ISSN 0012-9658
Ecological Society of America (ESA)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; 15N; food chain efficiency; food webs; isotope tracer experiment; nitrogen; stream
OSTI Identifier: