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dc.contributor.authorZinkann, Ann-Christine
dc.date.accessioned2020-10-03T22:37:05Z
dc.date.available2020-10-03T22:37:05Z
dc.date.issued2020-05
dc.identifier.urihttp://hdl.handle.net/11122/11304
dc.descriptionThesis (Ph.D.) University of Alaska Fairbanks, 2020en_US
dc.description.abstractClimate-change induced alterations of the organic matter flow from various primary production sources to the benthic system in the Arctic Chukchi Sea could have major implications on carbon cycling, sequestration, and benthic food web structure sustaining upper trophic levels. In particular, the role and contribution of terrestrial matter and bacterial matter could become more prominent, with increasing erosion and permafrost melt being discharged from land, and warming water temperatures raising bacterial metabolism. In this study, I used essential amino acid (EAA) specific stable isotope analysis to trace the proportional contributions of bacterial, phytoplankton, and terrestrial organic matter in sediments, as well as benthic invertebrates on the Chukchi Sea shelf. Across the upper 5 cm of sediments, most organic matter sources were equally distributed, except for a slight decrease with depth in phytoplankton EAA. Terrestrial sources contributed the majority of EAA (~76 %) in all sediment layers, suggesting a potential accumulation of this material due to slow degradation processes. These results indicate a well-mixed upper sediment horizon, possibly due to bioturbation activity by the abundant benthos. Experimental observations of increases in bacterial production, measured as phospholipid fatty acid (PLFA) production, at water temperatures 5 °C above ambient (0 °C) and under sufficient substrate conditions suggest that bacterial organic matter in sediments could become a greater organic matter source in the sediments of a future, warmer Arctic. EAA source contribution to various benthic invertebrate feeding types (FT) were similar but showed significant differences among genera within the same FT, suggesting that feeding habits are more genus-specific rather than FT-specific. These differences were attributed to variations in other characteristics such as mobility, selectivity, and assimilation efficiency. Terrestrial EAA contributed high amounts to all benthic genera, supporting other recent findings that this source is readily utilized by benthic invertebrate consumers. These results of organic matter source contributions across sediments and benthic invertebrate feeding types were then used to better resolve the detrital pathways in an Ecopath mass-balance model of the Chukchi Sea. The incorporation of terrestrial matter as an organic matter source to Chukchi Sea food webs and updated organic matter use in benthic invertebrate diets balanced energy flow from phytoplankton and bacterial production through the food web. Simulations of potential future reductions of the pelagic production to the benthos negatively impacted benthic feeding taxa, which could be partially compensated by a simulated increase in terrestrial and bacterial organic matter supply.en_US
dc.description.sponsorshipNational Oceanic and Atmospheric Administration cooperative agreement NA13OAR4320056, National Ocean Partnership Program (NOPP grant NA14NOS0120158 to KI), National Oceanographic and Atmospheric Administration (NOAA), Bureau of Ocean Management (BOEM), Shell Exploration & Productionen_US
dc.description.tableofcontentsChapter 1: Digging deep: depth distribution of organic matter sources in Arctic Chukchi Sea sediments -- Chapter 2: Does feeding type matter? Contribution of organic matter sources to benthic invertebrates on the Arctic Chukchi Sea shelf -- Chapter 3: The Arctic Chukchi Sea food web: simulating ecosystem impacts of future changes in organic matter flow -- General conclusion.en_US
dc.language.isoen_USen_US
dc.subjectseawateren_US
dc.subjectorganic compound contenten_US
dc.subjectChukchi Seaen_US
dc.subjectbenthic animalsen_US
dc.subjectmarine benthic ecologyen_US
dc.subjectbenthosen_US
dc.subjectArctic Oceanen_US
dc.titleOrganic matter sources on the Chukchi Sea shelf in a changing Arcticen_US
dc.typeThesisen_US
dc.type.degreephden_US
dc.identifier.departmentDepartment of Marine Biologyen_US
dc.contributor.chairIken, Katrin
dc.contributor.committeeWooller, Matthew
dc.contributor.committeeDanielson, Seth
dc.contributor.committeeLeigh, Mary Beth
dc.contributor.committeeGibson, Georgina
refterms.dateFOA2020-10-03T22:37:05Z


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