Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

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

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


Oregon State University

1. Clarke, Larissa M. Functional Comparison of Longline Oyster Aquaculture and Eelgrass (Zostera marina L.) Habitats Among Pacific Northwest Estuaries, USA.

Degree: MS, 2017, Oregon State University

Understanding the ecological role of Pacific oyster aquaculture (Crassostrea gigas) and eelgrass (Zostera marina L.) as important habitats in US Pacific Northwest estuaries is critical for management and regulatory decisions. The oyster aquaculture industry is currently restricted by regulations concerning impacts of their activities on Z. marina. This seagrass is protected under several legislative designations including Essential Fish Habitat (EFH) for federally managed fish species under the Magnuson Stevens Act. To date, federal and state regulations do not consider aquaculture as functional ecological habitat. While estuarine habitats serve multiple functions, the focus of our study was to evaluate fish and crab use. Underwater digital video surveys and minnow traps were used to quantify fish and crab abundance and behavior in longline oyster aquaculture, eelgrass beds, and the edge between these two habitats. Standardized predation tethering units (PTUs) were also deployed in each of these habitats to examine predation risk and refuge value. Our objective was not only to determine what fish and crab species were present, but also to determine whether their behavior could be used to clarify the functional role of these habitats and compare results among estuaries. Although there were no differences among habitat types in minnow trap catch, shiner perch (Cymatogaster aggregata) and Pacific staghorn sculpin (Leptocottus armatus) were the most common fish taken in all three estuaries. Shiner perch were sighted in Samish Bay video more frequently in longline aquaculture than in eelgrass while Pacific staghorn sculpin were more frequently sighted on the edge than in either oyster aquaculture or eelgrass. Additionally, behavior of fish and crab did not differ among habitat types in Samish Bay. Results of predation assays suggested that predation pressure was highest in Tillamook Bay and lowest in Samish Bay where an apparent edge effect is consistent with higher abundance of Pacific staghorn sculpins. While benthic structure provided by both eelgrass and oysters has previously been shown to be important, our results suggest that the form of the benthic structure (e.g. off-bottom versus on-bottom) and features such as edge habitats may also play an important role in PNW estuaries. Advisors/Committee Members: Dumbauld, Brett R. (advisor), Tomas Nash, Fiona (committee member).

Subjects/Keywords: longline oyster aquaculture

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

APA (6th Edition):

Clarke, L. M. (2017). Functional Comparison of Longline Oyster Aquaculture and Eelgrass (Zostera marina L.) Habitats Among Pacific Northwest Estuaries, USA. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/61776

Chicago Manual of Style (16th Edition):

Clarke, Larissa M. “Functional Comparison of Longline Oyster Aquaculture and Eelgrass (Zostera marina L.) Habitats Among Pacific Northwest Estuaries, USA.” 2017. Masters Thesis, Oregon State University. Accessed January 22, 2021. http://hdl.handle.net/1957/61776.

MLA Handbook (7th Edition):

Clarke, Larissa M. “Functional Comparison of Longline Oyster Aquaculture and Eelgrass (Zostera marina L.) Habitats Among Pacific Northwest Estuaries, USA.” 2017. Web. 22 Jan 2021.

Vancouver:

Clarke LM. Functional Comparison of Longline Oyster Aquaculture and Eelgrass (Zostera marina L.) Habitats Among Pacific Northwest Estuaries, USA. [Internet] [Masters thesis]. Oregon State University; 2017. [cited 2021 Jan 22]. Available from: http://hdl.handle.net/1957/61776.

Council of Science Editors:

Clarke LM. Functional Comparison of Longline Oyster Aquaculture and Eelgrass (Zostera marina L.) Habitats Among Pacific Northwest Estuaries, USA. [Masters Thesis]. Oregon State University; 2017. Available from: http://hdl.handle.net/1957/61776


Oregon State University

2. 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

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

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 January 22, 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. 22 Jan 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 Jan 22]. 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

.