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You searched for +publisher:"Oregon State University" +contributor:("Chan, Francis"). Showing records 1 – 3 of 3 total matches.

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Oregon State University

1. Adams, Katherine A. Influence of upwelling-season coastal currents on near-bottom dissolved oxygen concentrations over a submarine bank.

Degree: PhD, Oceanography, 2014, Oregon State University

Wind-driven coastal upwelling brings subsurface water onto the central-Oregon shelf after the spring transition each year. This cold and salty source water is oxygen-poor, yet above the hypoxic threshold, dissolved oxygen < 1.4 ml l⁻¹. Once on the shelf, dissolved oxygen (DO) concentrations of upwelled near-bottom waters are modified by physical and biological shelf processes, such as advection, mixing and microbial respiration. The influences of shelf processes on near-bottom DO concentrations on tidal, event and seasonal time scales are investigated using moored continuous time series and underwater glider cross-shelf transects over the Heceta and Stonewall Bank complex (HSBC) off central Oregon. A linear, seasonal decline rate of ~0.01 ml l⁻¹ day⁻¹ is observed from moored near-bottom continuous time series on the mid shelf over HSBC. This seasonal decline rate is only 30% of the expected draw down from calculated respiration rates over the shelf (0.026 ± 0.013 ml l⁻¹ day⁻¹). The severity of low-oxygen concentrations in a given year is a combined result of the biological consumption rate, the physical replenishment rate due to advection and mixing and the length of the season. Along the Newport Hydrographic (NH) line (44.65°N), cross-shelf variability of hypoxic measurements sampled in over 100 underwater glider cross-shelf transects (2006 - 2012) is investigated. Prevalent near-bottom hypoxic areas are identified on the mid (50-80-m isobaths) and the outer (120-150-m isobaths) shelf regions. The gap in between the two regions is just north of Stonewall Bank, an area of enhanced mixing where higher-DO water is likely mixed into the bottom mixed layer. A seasonal change in near-bottom currents is observed on the mid shelf. In early July of 2011, equatorward along-shelf currents weaken and near-bottom cross-shelf currents change from strongly onshore to weakly onshore and offshore. This change is likely due to the offshore movement of the coastal jet during the upwelling season. Consequently, bottom Ekman transport decreases significantly throughout the upwelling season. Low along-shelf and cross-shelf flow, or flushing, of near-bottom shelf waters increases the risk for hypoxia. Cross-shelf advection cannot account for the large decrease in outer-shelf DO observed in a sequence of 10 glider lines in late-summer 2011. This decrease is attributed to an along-shelf DO gradient of -0.72 ml l⁻¹ over 2.58 km, or 0.28 ml l⁻¹ per km, such that equatorward near-bottom flow brings low-DO water south past the NH line. The effect of the Heceta and Stonewall Bank complex on along-shelf variability of shelf and slope waters is investigated during the 2008 upwelling season by comparing the NH glider line with a glider line located just south of the Bank (Umpqua River - UR, 43.7°N). Spicy, subsurface poleward flows, characteristic of the California Undercurrent (CU), are observed along both lines in September 2008. Spice values are proportional to a salinity anomaly and thus can be positive and negative. High spice values… Advisors/Committee Members: Barth, John A. (advisor), Chan, Francis (committee member).

Subjects/Keywords: Hypoxia; Hypoxia (Water)  – Oregon  – Pacific Coast

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APA (6th Edition):

Adams, K. A. (2014). Influence of upwelling-season coastal currents on near-bottom dissolved oxygen concentrations over a submarine bank. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/52417

Chicago Manual of Style (16th Edition):

Adams, Katherine A. “Influence of upwelling-season coastal currents on near-bottom dissolved oxygen concentrations over a submarine bank.” 2014. Doctoral Dissertation, Oregon State University. Accessed December 02, 2020. http://hdl.handle.net/1957/52417.

MLA Handbook (7th Edition):

Adams, Katherine A. “Influence of upwelling-season coastal currents on near-bottom dissolved oxygen concentrations over a submarine bank.” 2014. Web. 02 Dec 2020.

Vancouver:

Adams KA. Influence of upwelling-season coastal currents on near-bottom dissolved oxygen concentrations over a submarine bank. [Internet] [Doctoral dissertation]. Oregon State University; 2014. [cited 2020 Dec 02]. Available from: http://hdl.handle.net/1957/52417.

Council of Science Editors:

Adams KA. Influence of upwelling-season coastal currents on near-bottom dissolved oxygen concentrations over a submarine bank. [Doctoral Dissertation]. Oregon State University; 2014. Available from: http://hdl.handle.net/1957/52417

2. Letzing, Sandy. Characterizing the response of coralline algae to ocean acidification and nutrient changes in the California Current system.

Degree: MS, Marine Resource Management, 2013, Oregon State University

Ocean acidification (OA) has emerged as an important focus of research and policy in this decade. Ocean acidification specifically refers to changes in the inorganic carbon system in the ocean resulting from its absorption of human-released CO₂ from the atmosphere. Anthropogenic atmospheric CO₂ levels are rapidly increasing; much of this is dissolved and absorbed in the ocean (~30%) where it reacts with seawater altering fundamental properties including pH, pCO₂ and saturation state of carbonate minerals. This change is of concern because of the potential of OA to disrupt biological processes, particularly those processes associated with calcification (Byrne, 2011; Diaz-Pilido, Anthony, Kline, Dove, & Hoegh-Guldberg, 2012). For this study, I chose to investigate red coralline algae as a model organism because OA is predicted to have effects on calcification and photosynthesis, and because of the importance of coralline algae as an ecological engineer, which can be found in shallow water habitats globally. While the response of coralline algae to OA is a serious concern, there remains very limited data on the interactions of OA with other ocean conditions (e.g., temperature, nutrients, and light) that may alter or modify the effects of low pH on coralline algae communities. One nutrient in particular, phosphorus is known to have inhibiting effects on calcification in long-term studies. My objective was to describe the short-term effects of a range of elevated pCO₂ and phosphorus levels both alone, and together, on calcification and photosynthetic rates of Corallina vancouveriensis. I exposed these algae to a range of pCO₂ and phosphate concentrations and measured changes in total alkalinity, pH, and DO in acute exposure trials (<3 hours). Corallina calcification rates were negatively affected by elevated pCO₂ levels and decreased proportionately across a range of pCO₂ from 300 to 2500 μatm. In contrast, exposure to elevated levels phosphate had no effect on Corallina calcification or photosynthesis. When exposed to both elevated levels of phosphate and pCO₂ together, I found no evidence of interactions between these factors. The results suggest that future atmospheric CO₂ levels will have an impact on the calcification rates of Corallina, and that these rates will not be influenced acutely by increasing levels of phosphate found in coastal oceans. Advisors/Committee Members: Chan, Francis (advisor), Nielson, Karina (committee member).

Subjects/Keywords: Corallina vancouveriensis; Coralline algae  – Oregon  – Fogarty Creek

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APA (6th Edition):

Letzing, S. (2013). Characterizing the response of coralline algae to ocean acidification and nutrient changes in the California Current system. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/44759

Chicago Manual of Style (16th Edition):

Letzing, Sandy. “Characterizing the response of coralline algae to ocean acidification and nutrient changes in the California Current system.” 2013. Masters Thesis, Oregon State University. Accessed December 02, 2020. http://hdl.handle.net/1957/44759.

MLA Handbook (7th Edition):

Letzing, Sandy. “Characterizing the response of coralline algae to ocean acidification and nutrient changes in the California Current system.” 2013. Web. 02 Dec 2020.

Vancouver:

Letzing S. Characterizing the response of coralline algae to ocean acidification and nutrient changes in the California Current system. [Internet] [Masters thesis]. Oregon State University; 2013. [cited 2020 Dec 02]. Available from: http://hdl.handle.net/1957/44759.

Council of Science Editors:

Letzing S. Characterizing the response of coralline algae to ocean acidification and nutrient changes in the California Current system. [Masters Thesis]. Oregon State University; 2013. Available from: http://hdl.handle.net/1957/44759

3. Reimer, Jessica N. Patterns of macrophyte wrack deposition on sandy beaches of the Pacific Northwest coast, U.S.A.

Degree: MS, Zoology, 2014, Oregon State University

Dislodged macroalgae and seagrasses, also known as marine wrack, frequently wash into coastal ecosystems from the ocean and are potentially important ecological resources for biological communities. These!nutrient and organic matter subsidies may be especially important on sandy beaches, where little in situ primary productivity exists for higher trophic levels. To better understand the prevalence of marine wrack as a coastal subsidy!to nutrient-poor sand and beachgrass ecosystems, we investigated the pattern of deposition and composition of wrack that washes onto Pacific Northwest sandy beach ecosystems. We conducted a large-scale, observational study at 12 coastal sites located from southern Washington to northern California to estimate the patch density, biomass, total biomass, and species composition of wrack on each beach. All sites were surveyed in both early summer and early fall to understand how the temporal patterns of certain processes (e.g., storms and algal senescence) affect wrack presence. Linear mixed-effect models were used to determine the effect of site location and season, as well as a suite of environmental predictors including cross-shore and alongshore upwelling and shoreline change rate (SCR). At all sites,!marine wrack increased in patch density and biomass on beaches in the fall suggesting that productivity over the summer, storm activity, and wave action in the fall may have affected the delivery of wrack. In terms of spatial distribution, wrack patch density (per m²) was greatest in the northern region (Greys Harbor to Sand Lake) and wrack biomass (per m²) was greatest in the southern region (Bandon to Cape Mendocino). However, overall total wrack biomass (per block), an integrative measure of patch density and biomass, was greatest in the south (Bandon to Cape Mendocino), intermediate in the north (Greys Harbor to Sand Lake), and lowest in the central region (South Beach to North Spit), although Greys Harbor and Cape Lookout in the north had similar amounts to sites in the southern region. Further analysis showed that cross-shore upwelling had a positive effect on wrack patch density and wrack biomass, while total biomass was not correlated with the environmental variables we tested. Composition varied predictably across the coast, with eelgrass present in greater proportions at northern sites and kelp present in greater proportions at central and southern sites. Kelp and eelgrass biomass were also strongly negatively influenced by distance from rocky reefs and estuaries, their respective source habitats (kelp biomass decreased further from rocky reefs, while eelgrass biomass decreased further from estuaries). In addition, kelp biomass was positively affected by SCR, while eelgrass biomass was negatively affected by cross-shore upwelling and positively affected by alongshore upwelling. This study, one of the first to examine large biogeographic scale patterns of wrack deposition, suggests that upwelling, outwelling (the movement of debris from estuaries… Advisors/Committee Members: Hacker, Sally D. (advisor), Chan, Francis (committee member).

Subjects/Keywords: subsidies; Marine algae  – Northwest, Pacific

…develop into a true scientist.! The Oregon State University Department of Zoology (now… 

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

APA (6th Edition):

Reimer, J. N. (2014). Patterns of macrophyte wrack deposition on sandy beaches of the Pacific Northwest coast, U.S.A. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/52782

Chicago Manual of Style (16th Edition):

Reimer, Jessica N. “Patterns of macrophyte wrack deposition on sandy beaches of the Pacific Northwest coast, U.S.A.” 2014. Masters Thesis, Oregon State University. Accessed December 02, 2020. http://hdl.handle.net/1957/52782.

MLA Handbook (7th Edition):

Reimer, Jessica N. “Patterns of macrophyte wrack deposition on sandy beaches of the Pacific Northwest coast, U.S.A.” 2014. Web. 02 Dec 2020.

Vancouver:

Reimer JN. Patterns of macrophyte wrack deposition on sandy beaches of the Pacific Northwest coast, U.S.A. [Internet] [Masters thesis]. Oregon State University; 2014. [cited 2020 Dec 02]. Available from: http://hdl.handle.net/1957/52782.

Council of Science Editors:

Reimer JN. Patterns of macrophyte wrack deposition on sandy beaches of the Pacific Northwest coast, U.S.A. [Masters Thesis]. Oregon State University; 2014. Available from: http://hdl.handle.net/1957/52782

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