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In 2010, a monthly sampling regimen was established to examine ecological differences in Saguaro Lake and Lake Pleasant, two Central Arizona reservoirs. Lake Pleasant is relatively deep and clear, while Saguaro Lake is relatively shallow and turbid. Preliminary results indicated that phytoplankton biomass was greater by an order of magnitude

In 2010, a monthly sampling regimen was established to examine ecological differences in Saguaro Lake and Lake Pleasant, two Central Arizona reservoirs. Lake Pleasant is relatively deep and clear, while Saguaro Lake is relatively shallow and turbid. Preliminary results indicated that phytoplankton biomass was greater by an order of magnitude in Saguaro Lake, and that community structure differed. The purpose of this investigation was to determine why the reservoirs are different, and focused on physical characteristics of the water column, nutrient concentration, community structure of phytoplankton and zooplankton, and trophic cascades induced by fish populations. I formulated the following hypotheses: 1) Top-down control varies between the two reservoirs. The presence of piscivore fish in Lake Pleasant results in high grazer and low primary producer biomass through trophic cascades. Conversely, Saguaro Lake is controlled from the bottom-up. This hypothesis was tested through monthly analysis of zooplankton and phytoplankton communities in each reservoir. Analyses of the nutritional value of phytoplankton and DNA based molecular prey preference of zooplankton provided insight on trophic interactions between phytoplankton and zooplankton. Data from the Arizona Game and Fish Department (AZGFD) provided information on the fish communities of the two reservoirs. 2) Nutrient loads differ for each reservoir. Greater nutrient concentrations yield greater primary producer biomass; I hypothesize that Saguaro Lake is more eutrophic, while Lake Pleasant is more oligotrophic. Lake Pleasant had a larger zooplankton abundance and biomass, a larger piscivore fish community, and smaller phytoplankton abundance compared to Saguaro Lake. Thus, I conclude that Lake Pleasant was controlled top-down by the large piscivore fish population and Saguaro Lake was controlled from the bottom-up by the nutrient load in the reservoir. Hypothesis 2 stated that Saguaro Lake contains more nutrients than Lake Pleasant. However, Lake Pleasant had higher concentrations of dissolved nitrogen and phosphorus than Saguaro Lake. Additionally, an extended period of low dissolved N:P ratios in Saguaro Lake indicated N limitation, favoring dominance of N-fixing filamentous cyanobacteria in the phytoplankton community in that reservoir.
ContributorsSawyer, Tyler R (Author) / Neuer, Susanne (Thesis advisor) / Childers, Daniel L. (Committee member) / Sommerfeld, Milton (Committee member) / Arizona State University (Publisher)
Created2011
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Description
This thesis was conducted in order to determine the role played by food miles metrics in making the agricultural industry more sustainable. In an effort to analyze the importance of eat locally this study utilizes a partial life cycle assessment. This study looks at oranges grown in Arizona and California

This thesis was conducted in order to determine the role played by food miles metrics in making the agricultural industry more sustainable. In an effort to analyze the importance of eat locally this study utilizes a partial life cycle assessment. This study looks at oranges grown in Arizona and California and inputs such as water, energy, fertilizer, herbicide, pesticide, frost mitigation, and distance in order to conduct the partial life cycle assessment. Results of this study indicate that food miles are not as significant, in relation to overall energy input, as the locavore movement claims. This is because production processes account for a larger portion of the total energy used in the food chain than what these claims suggest. While eating locally is still a significant way of reducing energy use, this thesis shows that decisions about eating sustainably should not only focus on the distance that the products travel, but place equal, if not more, importance on energy use differences due to geographic location and in-farm operations. Future research should be completed with more comprehensive impact categories and conducted for different crops, farming, and locations. Further research is needed in order to confirm or challenge the results of this thesis. With more research conducted regarding this topic, ecological labeling of agricultural products could be improved to help consumers make the most informed choices possible.
ContributorsMaggass, Melissa Gail (Author) / Manuel-Navarrete, David (Thesis director) / Martin, Thomas (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / W. P. Carey School of Business (Contributor) / Department of Management (Contributor)
Created2014-05
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Description
It is well known that deficiencies in key chemical elements (such as phosphorus, P) can reduce animal growth; however, recent empirical data have shown that high levels of dietary nutrients can also reduce animal growth. In ecological stoichiometry, this phenomenon is known as the "stoichiometric knife edge," but its underlying

It is well known that deficiencies in key chemical elements (such as phosphorus, P) can reduce animal growth; however, recent empirical data have shown that high levels of dietary nutrients can also reduce animal growth. In ecological stoichiometry, this phenomenon is known as the "stoichiometric knife edge," but its underlying mechanisms are not well-known. Previous work has suggested that the crustacean zooplankter Daphnia reduces its feeding rates on phosphorus-rich food, causing low growth due to insufficient C (energy) intake. To test for this mechanism, feeding rates of Daphnia magna on algae (Scenedesmus acutus) differing in C:P ratio (P content) were determined. Overall, there was a significant difference among all treatments for feeding rate (p < 0.05) with generally higher feeding rates on P-rich algae. These data indicate that both high and low food C:P ratio do affect Daphnia feeding rate but are in contradiction with previous work that showed that P-rich food led to strong reductions in feeding rate. Additional experiments are needed to gain further insights.
ContributorsSchimpp, Sarah Ann (Author) / Elser, James (Thesis director) / Neuer, Susanne (Committee member) / Peace, Angela (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Sustainability (Contributor)
Created2014-05
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Description
Current farming demographics in the United States indicate an aging and overwhelmingly white group of farmers, stimulating the need for engaging a younger and more diverse population. There is an opportunity to engage these populations through farm-based internship and apprenticeship programs, which are immersive programs on small-scale, sustainable farms. These

Current farming demographics in the United States indicate an aging and overwhelmingly white group of farmers, stimulating the need for engaging a younger and more diverse population. There is an opportunity to engage these populations through farm-based internship and apprenticeship programs, which are immersive programs on small-scale, sustainable farms. These programs are unique in providing hands-on training, housing, meals, and a stipend in return for labor, presenting a pathway to social empowerment. The potential outcomes of increasing diversity and inclusion in farm programs are absent from the research on the benefits of diversity and inclusion in other work environments, such as the corporate setting. This paper presents the results of a study aimed at determining levels of diversity and inclusion in United States farm-based internship programs, and the viability of these programs as an effective opportunity to engage marginalized young people in farming. The study of 13 farm owners and managers across the U.S. found that the participants are focused on fostering education and training, environmental benefits, and a sense of community in their respective programs. All participants either want to establish, or believe they currently have, an inclusive workplace on their farm, but also indicated a barrier to inclusivity in the lack of a diverse applicant pool. Future recommendations for removing that barrier and involving more young, diverse interns include increased outreach and access to these programs, the use of inclusive language, and further research.
ContributorsLascola, Dania (Co-author) / Biel, Braden (Co-author) / Cloutier, Scott (Thesis director) / MacFadyen, Joshua (Committee member) / School of International Letters and Cultures (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
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Description
The Prosopis genus of trees, also known as mesquites, are uniquely equipped to allow for an agroforestry regime in which crops can be grown beneath the canopy of the tree. Mesquites have the ability to redistribute water moisture in such a way that allows plants under the canopy to use

The Prosopis genus of trees, also known as mesquites, are uniquely equipped to allow for an agroforestry regime in which crops can be grown beneath the canopy of the tree. Mesquites have the ability to redistribute water moisture in such a way that allows plants under the canopy to use water that has been brought up by the roots of mesquite trees. This means that there is a potential for food crops to be grown under the trees without using additional irrigation measures. This could be used where access to water is limited or for a sustainability-minded farmer who is trying to reduce water inputs in an arid environment. Mesquite trees produce a variety of products, including lumber and bean pods that can be ground down into an edible flour. Both products demand a high price in the marketplace and are produced in addition to the crops that can potentially be grown beneath the mesquite tree. In order to determine whether or not it is possible to grow crops under mesquite trees, I reviewed a wide range of literature regarding hydraulic redistribution, mesquite trees in general, and what plants might be best suited for growing beneath a mesquite. The list of plants was narrowed down to four crops that seemed most likely to survive in shaded, low water conditions in a hot environment. There has not been any research done on crops growing beneath mesquite trees, so the next step for research would be to experiment with each of the crops to determine how well each species can adapt to the specified conditions.
ContributorsMesser, Luke Winston (Author) / Eakin, Hallie (Thesis director) / Hall, Sharon (Committee member) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
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Description
Microzooplankton, mainly heterotrophic unicellular eukaryotes (protists), play an important role in the cycling of nutrients and carbon in the sunlit (euphotic) zone of the world’s oceans. Few studies have investigated the microzooplankton communities in oligotrophic (low-nutrient) oceans, such as the Sargasso Sea. In this study, I investigate the seasonal and

Microzooplankton, mainly heterotrophic unicellular eukaryotes (protists), play an important role in the cycling of nutrients and carbon in the sunlit (euphotic) zone of the world’s oceans. Few studies have investigated the microzooplankton communities in oligotrophic (low-nutrient) oceans, such as the Sargasso Sea. In this study, I investigate the seasonal and interannual dynamics of the heterotrophic protists, particularly the nanoflagellate, dinoflagellate, and ciliate communities, at the Bermuda Atlantic Time Series site and surrounding areas in the Sargasso Sea. In addition, I test the hypotheses that the community is controlled though bottom-up and top-down processes. To evaluate the bottom-up hypothesis, that the protists are controlled by prey availability, I test whether the protist abundance co-varies with the abundance of potential prey groups. Predation experiments with zooplankton were conducted and analyzed to test top-down control on the protists. I found distinguishable trends in biomass of the different protist groups between years and seasons. Nanoflagellates and dinoflagellates had higher biomass during the summer (28 ± 5 mgC/m2 and 44 ± 21 mgC/m2) than during the winter (17 ± 8 mgC/m2 and 30 ± 11 mgC/m2). Ciliates displayed the opposite trend with a higher average biomass in the winter (15 ± 9 mgC/m2) than in summer (5 ± 2 mgC/m2). In testing my bottom-up hypothesis, I found weak but significant positive grazer/prey relationships that indicate that nanoflagellates graze on picophytoplankton in winter and on the pico-cyanobacterium Prochlorococcus in summer. I found evidence that ciliates graze on Synechococcus in winter. I found weak but significant negative correlation between dinoflagellates and Prochlorococcus in summer. The predation experiments testing the top-down hypothesis did not show a clear top-down control, yet other studies in the region carried out during our investigation period support predation of the protists by the zooplankton. Overall, my results suggest a combination of bottom-up and top-down controls on these heterotrophic protists, however, further investigation is necessary to reveal the detailed trophic dynamics of these communities.
ContributorsWolverton, Megan (Author) / Neuer, Susanne (Thesis advisor) / Hartnett, Hillary (Committee member) / Elser, James (Committee member) / Arizona State University (Publisher)
Created2016
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Description

Is there a mismatch between urban farmers’ perceptions of their farm’s environmental sustainability and its actual environmental impact? Focusing on the use of water and nutrients on each farm as described by the farmers through interviews, it is evident that there is some level of disconnect between ideals and practices.

Is there a mismatch between urban farmers’ perceptions of their farm’s environmental sustainability and its actual environmental impact? Focusing on the use of water and nutrients on each farm as described by the farmers through interviews, it is evident that there is some level of disconnect between ideals and practices. This project may aid in bridging the gap between the two in regard to the farmers’ sustainability goals. This project will move forward by continuing interviews with farmers as well as collecting soil and water from the farms in order to more accurately quantify the sustainability of the farms’ practices. This project demonstrates that there is some degree of misalignment between perception and reality. Two farms claimed they were sustainable when their practices did not reflect that, while 2 farms said they were not sure if they were sustainable when their practices indicated otherwise. Samples from two farms showed high concentrations of nutrients and salts, supporting the idea that there may be a mismatch between perceived and actual sustainability.

ContributorsBonham, Emma Eileen (Author) / Muenich, Rebecca (Thesis director) / Zanin, Alaina (Committee member) / Civil, Environmental and Sustainable Eng Program (Contributor) / School of Sustainability (Contributor) / School of Sustainable Engineering & Built Envirnmt (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description

As technology has evolved over time and the U.S. population increases each year, this thesis focuses on the ways in which food production has shifted from the original farm to table to industrialized, processed food systems. Through a rationalization perspective, this research looks to the history and repercussions of industrial

As technology has evolved over time and the U.S. population increases each year, this thesis focuses on the ways in which food production has shifted from the original farm to table to industrialized, processed food systems. Through a rationalization perspective, this research looks to the history and repercussions of industrial agriculture as it has shifted over time. The term over-industrialization is used to operationalize the state of our current production methods. These methods focus extensively on the least expensive and most rapid methods to produce large yields of food products and pay no mind to ethics, respect of culture, land, or quality of products. Today, there is a shroud the corporations have placed over food production to ensure a “what we can’t see doesn’t affect us” belief system. In this way, the thesis provides insight on past, current, and future methods of manufacturing. I conclude that although plausible alternatives are present, continued research and substantial producer and consumer changes must be our main priority.

ContributorsBrodkin, Emma (Author) / Keahey, Jennifer (Thesis director) / Perkins, Tracy (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / School of Social and Behavioral Sciences (Contributor)
Created2023-05
Description

Animal agriculture is a growing industry worldwide as the global demand for animal products increases. This has resulted in many harmful unintended consequences for human health, the environment, and animal welfare. This paper aims to uncover the hidden costs of negative externalities by answering the question: What types of subsidies

Animal agriculture is a growing industry worldwide as the global demand for animal products increases. This has resulted in many harmful unintended consequences for human health, the environment, and animal welfare. This paper aims to uncover the hidden costs of negative externalities by answering the question: What types of subsidies is the US government distributing to the animal agriculture industry and in what amount? This paper will begin with some background on a few of the externalities created by the animal agriculture industry focusing specifically on environmental issues of water, air, and deforestation. Once this background is established, this will show that animal agriculture is in fact a negative-externality-generating industry. Next, subsidies will be defined and the principal findings of the research will reveal the different forms of support that the US government provides to animal agriculture. Lastly, these subsidies, both direct and indirect, will be quantified.

ContributorsEpel, Erin (Author) / Barca, Lisa (Thesis director) / Rao, Sailesh (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / School of International Letters and Cultures (Contributor)
Created2023-05
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Description

In the Southwestern United States, climate change poses challenges to reliable water access due to droughts, wildfires, and urban development. Arizonan farmers are faced with unpredictable precipitation, muddled legal water rights, and outdated equipment to irrigate their land. Located in Northern Arizona, Verde Valley residents and stakeholders are challenging the

In the Southwestern United States, climate change poses challenges to reliable water access due to droughts, wildfires, and urban development. Arizonan farmers are faced with unpredictable precipitation, muddled legal water rights, and outdated equipment to irrigate their land. Located in Northern Arizona, Verde Valley residents and stakeholders are challenging the way the Verde River water is managed through collaboration, partnerships, and technical changes to water infrastructure. Through interviews conducted with various stakeholders involved in the Verde River ditch irrigation system, ranging from water users to nonprofit organizations, this paper identifies sociotechnical tinkering as an important aspect of maintaining agricultural operations along the river amid political tensions, social relations, and climate change. Through interviews and analysis, this paper further contributes to the relatively new discourse on the concept of sociotechnical tinkering by proving its existence and its subsequent effectiveness in the Verde Valley. Using statements made by respondents, the paper argues that sociotechnical tinkering helps manage resources through political and social relations.

ContributorsNichols, Claire (Author) / Wutich, Amber (Thesis director) / Quimby, Barbara (Committee member) / Barrett, The Honors College (Contributor) / Environmental and Resource Management (Contributor) / School of Sustainability (Contributor) / School of Geographical Sciences and Urban Planning (Contributor)
Created2021-12