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dc.contributor.authorTant, Cynthia Janelle
dc.date.accessioned2014-03-04T20:25:22Z
dc.date.available2014-03-04T20:25:22Z
dc.date.issued2011-12
dc.identifier.othertant_cynthia_j_201112_phd
dc.identifier.urihttp://purl.galileo.usg.edu/uga_etd/tant_cynthia_j_201112_phd
dc.identifier.urihttp://hdl.handle.net/10724/27832
dc.description.abstractNutrient enrichment of aquatic ecosystems is occurring globally as a result of mobilization of nitrogen and phosphorus from a variety of anthropogenic sources. Responses to enrichment in detritus-based systems are not as well documented as those in autotroph-based systems. This study examined the effects of enrichment on a Southern Appalachian headwater stream on detrital resources and associated consumers. Heterotrophic microbes, particularly fungi, may perform a keystone function in headwater streams by facilitating carbon and nutrient flow to consumers and in the processing of allochthonous organic matter. I assessed the effect of nutrient enrichment on the relative contribution of decomposers and detritivores. I also examined changes on different size fractions of organic matter resources with enrichment and relationships between microbial biomass and nutrient content. Application of the Hieber-Gessner model suggests that nutrient enrichment may cause shifts toward increasing fungal and shredder contribution to leaf litter breakdown, intensifying losses of carbon through both respiration and downstream transport. The response of CPOM (both maple and rhododendron substrates) to enrichment was primarily positive, but the response of FBOM to enrichment was unexpectedly low. Nutrient enrichment increased fungal biomass and microbial respiration and decreased C:N and C:P on CPOM substrates, suggesting a general increase in resource quality. Estimates of TERs and comparison to associated organic matter resources in each stream suggest that enrichment may reduce P limitation for shredders while potentially increasing C limitation for collectors. In a laboratory setting, CPOM mass loss and FPOM production were highest in treatments with both fungi and elevated nutrients. Both the presence of fungi and exogenous nutrients affected the N content of CPOM, but only nutrients had an effect on P content. Although fungi increased the availability of FPOM, the combined effects of fungi and nutrients did not appear to trickle down to FPOM nutrient content during organic matter transformations. These results highlight potential mechanisms for food web shifts and pathways of carbon processing that may result from nutrient enrichment of detritus-based systems.
dc.languageeng
dc.publisheruga
dc.rightspublic
dc.subjectHeadwater stream
dc.subjectDetritus
dc.subjectDetritivore
dc.subjectHeterotrophic microbe
dc.subjectFungi
dc.subjectBacteria
dc.subjectNitrogen
dc.subjectPhosphorus
dc.subjectNutrient enrichment
dc.subjectPycnopsyche
dc.subjectCoweeta
dc.subjectSouthern Appalachian
dc.titleDetrital carbon response to experimental enrichment and impacts on associated consumers in a headwater stream
dc.typeDissertation
dc.description.degreePhD
dc.description.departmentInstitute of Ecology
dc.description.majorEcology
dc.description.advisorAmy Rosemond
dc.description.committeeAmy Rosemond
dc.description.committeeCatherine Pringle
dc.description.committeeMary C. Freeman
dc.description.committeeMark Bradford
dc.description.committeeDarold Batzer


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