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An Ecological and Biogeochemical Study of Dissolved Silicon in Human-Dominated Freshwater Ecosystems.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	An Ecological and Biogeochemical Study of Dissolved Silicon in Human-Dominated Freshwater Ecosystems./
作者:	Sethna, Lienne Rochelle.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2022,
面頁冊數:	190 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-11, Section: B.
Contained By:	Dissertations Abstracts International83-11B.
標題:	Aquatic sciences. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29168067
ISBN:	9798438756842

An Ecological and Biogeochemical Study of Dissolved Silicon in Human-Dominated Freshwater Ecosystems.
Sethna, Lienne Rochelle.

An Ecological and Biogeochemical Study of Dissolved Silicon in Human-Dominated Freshwater Ecosystems. - Ann Arbor : ProQuest Dissertations & Theses, 2022 - 190 p.

Source: Dissertations Abstracts International, Volume: 83-11, Section: B.

Thesis (Ph.D.)--Indiana University, 2022.

This item must not be sold to any third party vendors.

Freshwater ecosystems are critical in the biogeochemical processing of nutrients such as carbon (C), nitrogen (N), phosphorus (P), and silicon (Si). The relative proportions of these nutrients are key determinants of algal community composition and, subsequently, the water quality and trophic dynamics of aquatic systems. Human landscape modifications such as agriculture and reservoirs elevate the ratios of N and P relative to Si, leading to stoichiometric imbalance and nutrient limitation. The motivation for my research is the recognition that decreased availability of Si relative to N and P can limit diatom growth and facilitate the formation of harmful algal blooms. In this study, I seek to characterize the Si:N:P stoichiometry in human-dominated, freshwater ecosystems and fill critical knowledge gaps in our understanding of the relationship between nutrients, algal community composition, and dissolved organic matter (DOM). I monitored agricultural runoff at both the field- and watershed-scales to examine the response of Si concentrations and ratios to changing hydrology and vegetation cover and the corresponding risk of harmful algal bloom formation. Based on these findings, I sought to quantify the Si limitation of benthic diatoms, which require Si, and relate changes in algal community composition to nutrient availability. To understand Si dynamics within a reservoir, I constructed an annual Si budget for Lake Monroe, the largest reservoir in Indiana, and identified mechanisms controlling Si retention. We further analyzed the relationship between Si, algae, and DOM to determine how shifts in nutrient concentrations affect dissolved organic carbon composition. As expected, the agricultural study streams had excess N relative to Si which became increasingly imbalanced at higher flows. I therefore hypothesized benthic diatoms would be Si-limited; however, experimental Si enrichment did not increase algal biomass or the relative proportion of diatoms, highlighting the heterogeneity of benthic communities in headwater streams. I also found Lake Monroe retained about 40% of the incoming Si which was largely mediated by diatom growth and sequestration. Furthermore, components of DOM were highly correlated with the relative abundances of both diatom and harmful algal taxa suggesting the optical properties of DOM are sensitive to algal community composition. My dissertation adds to the growing body of literature in Si biogeochemistry and addresses novel concepts such as the quantification of Si limitation in streams and the coupling between DOM and Si stoichiometry.

ISBN: 9798438756842Subjects--Topical Terms:

3174300
Aquatic sciences.
Subjects--Index Terms:

Biogeochemistry

An Ecological and Biogeochemical Study of Dissolved Silicon in Human-Dominated Freshwater Ecosystems.
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500 $a Source: Dissertations Abstracts International, Volume: 83-11, Section: B.
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520 $a Freshwater ecosystems are critical in the biogeochemical processing of nutrients such as carbon (C), nitrogen (N), phosphorus (P), and silicon (Si). The relative proportions of these nutrients are key determinants of algal community composition and, subsequently, the water quality and trophic dynamics of aquatic systems. Human landscape modifications such as agriculture and reservoirs elevate the ratios of N and P relative to Si, leading to stoichiometric imbalance and nutrient limitation. The motivation for my research is the recognition that decreased availability of Si relative to N and P can limit diatom growth and facilitate the formation of harmful algal blooms. In this study, I seek to characterize the Si:N:P stoichiometry in human-dominated, freshwater ecosystems and fill critical knowledge gaps in our understanding of the relationship between nutrients, algal community composition, and dissolved organic matter (DOM). I monitored agricultural runoff at both the field- and watershed-scales to examine the response of Si concentrations and ratios to changing hydrology and vegetation cover and the corresponding risk of harmful algal bloom formation. Based on these findings, I sought to quantify the Si limitation of benthic diatoms, which require Si, and relate changes in algal community composition to nutrient availability. To understand Si dynamics within a reservoir, I constructed an annual Si budget for Lake Monroe, the largest reservoir in Indiana, and identified mechanisms controlling Si retention. We further analyzed the relationship between Si, algae, and DOM to determine how shifts in nutrient concentrations affect dissolved organic carbon composition. As expected, the agricultural study streams had excess N relative to Si which became increasingly imbalanced at higher flows. I therefore hypothesized benthic diatoms would be Si-limited; however, experimental Si enrichment did not increase algal biomass or the relative proportion of diatoms, highlighting the heterogeneity of benthic communities in headwater streams. I also found Lake Monroe retained about 40% of the incoming Si which was largely mediated by diatom growth and sequestration. Furthermore, components of DOM were highly correlated with the relative abundances of both diatom and harmful algal taxa suggesting the optical properties of DOM are sensitive to algal community composition. My dissertation adds to the growing body of literature in Si biogeochemistry and addresses novel concepts such as the quantification of Si limitation in streams and the coupling between DOM and Si stoichiometry.
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650 4 $a Biogeochemistry. $3 545717
650 4 $a Ecology. $3 516476
653 $a Biogeochemistry
653 $a Freshwater ecosystems
653 $a Nutrient
653 $a Silicon
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690 $a 0425
690 $a 0329
710 2 $a Indiana University. $b Environmental Science. $3 1269380
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793 $a English
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