Show simple item record

dc.contributor.authorMehring, Andrew Stephen
dc.date.accessioned2014-03-04T20:33:12Z
dc.date.available2014-03-04T20:33:12Z
dc.date.issued2012-05
dc.identifier.othermehring_andrew_s_201205_phd
dc.identifier.urihttp://purl.galileo.usg.edu/uga_etd/mehring_andrew_s_201205_phd
dc.identifier.urihttp://hdl.handle.net/10724/28050
dc.description.abstractMany rivers periodically experience system-wide hypoxia, sometimes without significant nutrient loading. The primary goal of a long-term project titled “Dissolved Oxygen Dynamics in the Upper Suwannee River Basin” was to determine factors (natural or anthropogenic) contributing to low dissolved oxygen concentrations observed in Georgia’s coastal plain blackwater rivers. As a project component, this study assessed effects of organic matter processing on oxygen demand in third-order-stream and fifth-order-swamp reaches of southern Georgia’s Little River. Differences in microbial biomass explained variation in leaf litter oxygen and nutrient uptake among tree species, but nutrient uptake was additionally affected by aluminum and iron accumulating in litter. Microbial biomass was negatively correlated to litter chemistry parameters such as the lignocellulose index, and while labile litter supports higher microbial oxygen uptake, it is also preferentially colonized by macroinvertebrates and breaks down more rapidly. Therefore, recalcitrant litter may make greater long-term contributions to oxygen demand. Detrital standing stocks consisted primarily of leaf litter, but bald cypress (Taxodium distichum) produced significantly more litter per trunk biomass relative to other species in the swamp. Estimates of leaf litter microbial respiration (5.54 g O2 m-2·day-1) accounted for 89% of sediment oxygen demand (SOD) measured by other researchers (6.20 g O2 m-2·day-1) in the same river, illustrating the importance of leaf litter breakdown to overall SOD. Although breakdown rates were faster in the swamp than in the stream, a greater percentage of initial leaf litter standing stocks were retained (54% vs. 30%) in the swamp, potentially due to lower water velocity. Over a seven-year study period, dissolved organic carbon (DOC) transport decreased substantially as annual dry period length increased, while DOC concentration and mineralization were enhanced at low flows. Although DOC mineralization was a small source of oxygen demand (roughly 4%) compared to leaf litter breakdown, our findings suggest that as droughts intensify, temperatures rise, and discharge decreases, enhanced DOC mineralization and reduced downstream DOC export may occur. Research presented here demonstrates that leaf litter accounts for a large natural source of oxygen demand, and illustrates the complex interactions affecting organic matter processing in a Georgia coastal plain blackwater river.
dc.languageeng
dc.publisheruga
dc.rightspublic
dc.subjectAluminum
dc.subjectBacteria
dc.subjectCellulose
dc.subjectClimate change
dc.subjectDissolved organic carbon
dc.subjectDissolved oxygen
dc.subjectDO
dc.subjectDOC
dc.subjectDrought
dc.subjectEEM
dc.subjectFungi
dc.subjectHypoxia
dc.subjectIron
dc.subjectPARAFAC
dc.subjectRespiration
dc.subjectLignin
dc.subjectLignocellulose index
dc.subjectManganese
dc.subjectNutrients
dc.subjectNyssa
dc.subjectTaxodium
dc.titleEffects of organic matter processing on oxygen demand in a south Georgia blackwater river
dc.typeDissertation
dc.description.degreePhD
dc.description.departmentInstitute of Ecology
dc.description.majorEcology
dc.description.advisorCatherine Pringle
dc.description.advisorGeorge Vellidis
dc.description.committeeCatherine Pringle
dc.description.committeeGeorge Vellidis
dc.description.committeeAmy D. Rosemond
dc.description.committeeR. Richard Lowrance
dc.description.committeeKevin A. Kuehn
dc.description.committeeRobert J. Cooper


Files in this item

FilesSizeFormatView

There are no files associated with this item.

This item appears in the following Collection(s)

Show simple item record