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You searched for +publisher:"Oregon State University" +contributor:("Dewitt, Ted"). Showing records 1 – 2 of 2 total matches.

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Oregon State University

1. Motley, Jennifer. Local and Regional Patterns in Eelgrass (Zostera marina L.) Communities Along an Upwelling-Productivity Gradient in Oregon Estuaries, USA.

Degree: MS, 2017, Oregon State University

In this thesis, I investigate the organization of eelgrass (Zostera marina L.) and mesograzer communities across local and regional scales in three upwelling- influenced estuaries located along the Oregon coast, USA. Eelgrass ecosystems are an important source of primary production in estuarine systems, providing numerous ecosystem services, including nursery habitat for commercial fish, water quality improvement, and sediment stabilization. Community structure in eelgrass systems, i.e., the diversity, abundance, and composition of primary and secondary consumers, is influenced by a combination of local to regional scale variability in environmental and biotic factors. Thus, an important consideration in the management of these systems is to understand the organization of community structure across spatiotemporal scale and the implications for top-down (consumer) versus bottom-up (resource) control. In upwelling-influenced estuaries of the Pacific Northwest coast of the United States, eelgrass systems are exposed to latitudinal variability in oceanographic inputs, but the degree to which these regional effects versus local effects organize eelgrass community structure is poorly understood. Here I investigate the relationship between primary producers (eelgrass, ulvoid macroalgae, and epiphytes), epifauna mesograzers, and fish predators within and across three estuaries located on the Oregon Coast, USA (Netarts Bay, Yaquina Bay, and Coos Bay). Specifically, I asked: 1) What is the relative importance of local (within estuary) versus regional (across estuaries) scale patterns to eelgrass community structure (i.e., primary producers, epifaunal mesograzers, and fishes) in upwelling-influenced estuaries in Oregon?, 2) What is the potential role of regional oceanography versus trophic interactions in regulating eelgrass community structure, and is this dependent on spatial scale?, and 3) What are the management implications for eelgrass communities when regional and local scales are considered? I found that while local effects were important, regional (estuary) scale patterns strongly influenced community structure in eelgrass communities, providing support that regional oceanographic bottom-up forcing dominates eelgrass communities. Additionally, I found evidence for top-down control by the opisthobranch Phyllaplysia taylori on primary producers at one site within Netarts Bay. I suggest that eelgrass beds in these estuaries are mostly bottom-up systems, and further investigations should focus on quantifying the mechanistic relationship between mesograzers and primary producers at local to regional scales. Advisors/Committee Members: Tomas Nash, Fiona (advisor), Dewitt, Ted (committee member).

Subjects/Keywords: seagrass; ulvoid macroalgae; epiphytes; epifaunal mesograzer; fish; trophic cascade; top-down; bottom-up; context-dependent; Phyllaplysia taylori; California Current System; Netarts Bay; Yaquina Bay; Coos Bay; Oregon; Pacific Northwest coast

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APA (6th Edition):

Motley, J. (2017). Local and Regional Patterns in Eelgrass (Zostera marina L.) Communities Along an Upwelling-Productivity Gradient in Oregon Estuaries, USA. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/61713

Chicago Manual of Style (16th Edition):

Motley, Jennifer. “Local and Regional Patterns in Eelgrass (Zostera marina L.) Communities Along an Upwelling-Productivity Gradient in Oregon Estuaries, USA.” 2017. Masters Thesis, Oregon State University. Accessed March 04, 2021. http://hdl.handle.net/1957/61713.

MLA Handbook (7th Edition):

Motley, Jennifer. “Local and Regional Patterns in Eelgrass (Zostera marina L.) Communities Along an Upwelling-Productivity Gradient in Oregon Estuaries, USA.” 2017. Web. 04 Mar 2021.

Vancouver:

Motley J. Local and Regional Patterns in Eelgrass (Zostera marina L.) Communities Along an Upwelling-Productivity Gradient in Oregon Estuaries, USA. [Internet] [Masters thesis]. Oregon State University; 2017. [cited 2021 Mar 04]. Available from: http://hdl.handle.net/1957/61713.

Council of Science Editors:

Motley J. Local and Regional Patterns in Eelgrass (Zostera marina L.) Communities Along an Upwelling-Productivity Gradient in Oregon Estuaries, USA. [Masters Thesis]. Oregon State University; 2017. Available from: http://hdl.handle.net/1957/61713


Oregon State University

2. Fritz, Cara E. A seasonal study of sediment reworking by Neotrypaea californiensis in Yaquina Bay, Oregon.

Degree: MS, Oceanography, 2002, Oregon State University

A year-long field study was undertaken to investigate the influence of a number of physical and biological factors, specifically temperature, organic carbon content, and shrimp population dynamics on sediment reworking rates by the ghost shrimp Neotrypaea calforniensis. Because of its role as a structuring agent in estuaries along the West Coast, it is important to understand the factors that impact shrimp reworking rates. At a site in the intertidal of Yaquina Bay, Oregon, measurements of sediment reworking (via direct entrapment of sediment ejected from burrows) were taken at monthly intervals over the course of a 15-month period. Abiotic (temperature, organic carbon content) and biotic parameters (shrimp size, density) were measured concurrently. Rates of reworking normalized to shrimp biomass/m² varied over the year, with lows in the winter months and a peak in August. This pattern corresponds closely to temperature fluctuations. Although a deep subsurface deposit feeder, the close correspondence between reworking activity and temperature indicates that Neotrypaea is in close contact with conditions at the sediment surface. Taking into consideration the decrease in shrimp abundance over the year, the amount of sediment reworked over a given area ranged from 2.7 to 41.0 g dry sediment/hr/m². The peak in overall reworking for this site was in early spring, which has implications for recruitment of benthic organisms. Observations on food availability at feeding depths and sediment turnover rates, from direct entrapment and a heavy mineral tracer experiment, suggest that the ghost shrimp may obtain nutritional material using methods aside from ingesting particles that are subducted to depth. Advisors/Committee Members: Wheatcroft, Robert A. (advisor), DeWitt, Ted (committee member).

Subjects/Keywords: Bay ghost shrimp  – Oregon  – Yaquina Bay

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Fritz, C. E. (2002). A seasonal study of sediment reworking by Neotrypaea californiensis in Yaquina Bay, Oregon. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/22928

Chicago Manual of Style (16th Edition):

Fritz, Cara E. “A seasonal study of sediment reworking by Neotrypaea californiensis in Yaquina Bay, Oregon.” 2002. Masters Thesis, Oregon State University. Accessed March 04, 2021. http://hdl.handle.net/1957/22928.

MLA Handbook (7th Edition):

Fritz, Cara E. “A seasonal study of sediment reworking by Neotrypaea californiensis in Yaquina Bay, Oregon.” 2002. Web. 04 Mar 2021.

Vancouver:

Fritz CE. A seasonal study of sediment reworking by Neotrypaea californiensis in Yaquina Bay, Oregon. [Internet] [Masters thesis]. Oregon State University; 2002. [cited 2021 Mar 04]. Available from: http://hdl.handle.net/1957/22928.

Council of Science Editors:

Fritz CE. A seasonal study of sediment reworking by Neotrypaea californiensis in Yaquina Bay, Oregon. [Masters Thesis]. Oregon State University; 2002. Available from: http://hdl.handle.net/1957/22928

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