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The Role of Terrestrial Organic Matter in the Lower Aquatic Food Web
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | The Role of Terrestrial Organic Matter in the Lower Aquatic Food Web. |
| 개인저자 | Harfmann, Jennifer Lynne. |
| 단체저자명 | University of California, Davis. Agricultural and Environmental Chemistry. |
| 발행사항 | [S.l.]: University of California, Davis., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 116 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-03B. Dissertation Abstract International |
| ISBN | 9781085794985 |
| 학위논문주기 | Thesis (Ph.D.)--University of California, Davis, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-03, Section: B.
Advisor: Hernes, Peter J. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Terrestrial organic matter (tOM) is a major contributor to global biogeochemical cycling, fundamentally linking pools of terrestrial and marine carbon, and can also influence and be influenced by local biogeochemical processes mediated by the lower aquatic food web. The goal of this research was to assess the interactions between tOM quality and primary consumers (bacteria and zooplankton) in order to constrain places and times where tOM source inputs are most influential in supporting the aquatic food web. Specific objectives included (1) evaluating compositional changes in vascular plant leachate dissolved organic matter (DOM) mediated by microbial and photochemical-microbial degradation, (2) constraining and calibrating vascular plant source biomarkers through microbial incubations, and (3) assessing zooplankton consumption of vascular plant particulates and survival across a variety of particulate organic matter (POM) diets. Microbial and photochemical-microbial incubations of four vascular plant leachates (ponderosa pine, blue oak, mixed annual grasses, mixed tule/cattail) indicated that despite initial variability in vascular plant source composition, degradation of dissolved tOM led to both optical and chemical convergence. Loss of source characteristics suggests that dissolved tOM source endmembers are much less significant than might be expected in dictating downstream microbial bioavailability, and compositional convergence may serve to buffer aquatic ecosystems when riparian landscapes (and subsequent terrestrial inputs) change. Constraining dissolved tOM source endmembers is crucial in quantifying pools and fluxes that dictate global biogeochemical budgets. Using endmembers derived from our microbial degradation experiments, we estimated that vascular plant material contributions to Arctic, temperate, and tropical riverine DOM averaged 16%, 48%, and 73%, respectively, supporting that, particularly in low DOM systems, a significant proportion of the DOM pool is unaccounted for by vascular plant biomarkers. Constraining non-vascular (e.g. microbial) endmembers proved more challenging and highlighted that microbial processing of tOM may be characterized by small molecular changes in functional groups rather than remineralization and production of new microbial compounds. While microbial utilization of dissolved tOM is a widely accepted phenomenon, incorporation of particulate tOM into the aquatic food web is less certain. A novel DNA metagenomic sequencing technique was developed to track zooplankton consumption of particulate tOM relative to algal resources. Zooplankton feeding experiments indicated that copepods not only consume particulate tOM (assessed chemically and genetically via gut content) but do so deliberately and confer benefits from it (i.e. increased survival) when other food resources such as phytoplankton are limited. Particulate tOM can therefore act as a lifeline for zooplankton in tidal wetlands or other aquatic systems with high amounts of tOM and low phytoplankton primary productivity. |
| 일반주제명 | Aquatic sciences. Environmental science. Geochemistry. |
| 언어 | 영어 |
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