The effects of N and P supply on invertebrate foodwebs: an experimental test of ecological stoichiometry in detritus-based ecosystems

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dc.contributor Huryn, Alexander D.
dc.contributor Findlay, Robert H.
dc.contributor Cross, Wyatt F.
dc.contributor Atkinson, Carla L.
dc.contributor.advisor Benstead, Jonathan P. Demi, Lee Michael 2017-03-02T19:55:09Z 2017-03-02T19:55:09Z 2016
dc.identifier.other u0015_0000001_0002523
dc.identifier.other Demi_alatus_0004D_12952
dc.description Electronic Thesis or Dissertation
dc.description.abstract In the last several decades, ecological stoichiometry has emerged as a promising framework for predicting how shifts in the relative availability of N and P influence biological processes from cellular to ecosystem scales. However, explicit tests of ecological stoichiometry theory from ecosystem scale experiments remain rare. In this dissertation, I present the results of a three year experiment where five detritus-based headwater streams were continuously fertilized with N and P at different concentrations, creating a range of molar N:P ratios (from 2:1 to 128:1), for two years following one year of pre-nutrient enrichment monitoring. Nutrient enrichment of the five detritus-based streams resulted in significant shifts in the N and P content of leaf detritus, which is the primary food resource for the invertebrate communities. Patterns of invertebrate productivity among the five streams were closely related to the N:P ratio of leaf detritus, providing strong evidence of food web P-limitation. In addition to effects on overall productivity, nutrient enrichment resulted in shifts in the taxonomic composition of the resident invertebrate community, which were largely driven by increased biomass of a few common detritivores. Nutrient enrichment also had significant effects on organic matter flows within the detrital food webs, as flows of all detrital resources to consumers increased following nutrient enrichment. Increased organic matter flows were necessary to support higher rates of invertebrate production following enrichment and were significantly related to the N:P ratio of leaf detritus, which accounted for ~2/3 of total organic matter flows. Furthermore, invertebrates consumed a greater proportion of the total mass of leaf litter lost from these systems annually following enrichment, a pattern that was once again driven by the N:P ratio of leaf litter. The results of this study provide compelling support for ecological stoichiometry as a framework for predicting consequences of altered N and P dynamics. Our ability to predict how ecosystems respond to shifting N and P availability remains an important challenge in contemporary ecological research given the globally pervasive nature of anthropogenic impacts on biogeochemical N and P cycles.
dc.format.extent 146 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Ecology
dc.title The effects of N and P supply on invertebrate foodwebs: an experimental test of ecological stoichiometry in detritus-based ecosystems
dc.type thesis
dc.type text University of Alabama. Dept. of Biological Sciences Biological Sciences The University of Alabama doctoral Ph.D.

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