Matching Items (155)
Description
In this synthesis, we hope to accomplish two things: 1) reflect on how the analysis of the new archaeological cases presented in this special feature adds to previous case studies by revisiting a set of propositions reported in a 2006 special feature, and 2) reflect on four main ideas that are more specific to the archaeological cases: i) societal choices are influenced by robustness–vulnerability trade-offs, ii) there is interplay between robustness–vulnerability trade-offs and robustness–performance trade-offs, iii) societies often get locked in to particular strategies, and iv) multiple positive feedbacks escalate the perceived cost of societal change. We then discuss whether these lock-in traps can be prevented or whether the risks associated with them can be mitigated. We conclude by highlighting how these long-term historical studies can help us to understand current society, societal practices, and the nexus between ecology and society.
ContributorsSchoon, Michael (Author) / Fabricius, Christo (Author) / Anderies, John (Author) / Nelson, Margaret (Author) / College of Liberal Arts and Sciences (Contributor)
Created2011
Description
Phytoplankton comprise the base of the marine food web, and, along with heterotrophic protists, they are key players in the biological pump that transports carbon from the surface to the deep ocean. In the world's subtropical oligotrophic gyres, plankton communities exhibit strong seasonality. Winter storms vent deep water into the euphotic zone, triggering a surge in primary productivity in the form of a spring phytoplankton bloom. Although the hydrographic trends of this "boom and bust" cycle have been well studied for decades, community composition and its seasonal and annual variability remains an integral subject of research. It is hypothesized here that proportions of different phytoplankton and protistan taxa vary dramatically between seasons and years, and that picoplankton represent an important component of this community and contributor to carbon in the surface ocean. Monthly samples from the Bermuda Atlantic Time-series Study (BATS) site were analyzed by epifluorescence microscopy, which permits classification by morphology, size, and trophic type. Epifluorescence counts were supplemented with flow cytometric quantification of Synechococcus, Prochlorococcus, and autotrophic pico- and nanoeukaryotes. Results from this study indicate Synechococcus and Prochlorococcus, prymnesiophytes, and hetero- and mixotrophic nano- and dinoflagellates were the major players in the BATS region plankton community. Ciliates, cryptophytes, diatoms, unidentified phototrophs, and other taxa represented rarer groups. Both flow cytometry and epifluorescence microscopy revealed Synechococcus to be most prevalent during the spring bloom. Prymnesiophytes likewise displayed distinct seasonality, with the highest concentrations again being noted during the bloom. Heterotrophic nano- and dinoflagellates, however, were most common in fall and winter. Mixotrophic dinoflagellates, while less abundant than their heterotrophic counterparts, displayed similar seasonality. A key finding of this study was the interannual variability revealed between the two years. While most taxa were more abundant in the first year, prymnesiophytes experienced much greater abundance in the second year bloom. Analyses of integrated carbon revealed further stark contrasts between the two years, both in terms of total carbon and the contributions of different groups. Total integrated carbon varied widely in the first study year but displayed less fluctuation after June 2009, and values were noticeably reduced in the second year.
ContributorsHansen, Amy (Author) / Neuer, Susanne (Thesis advisor) / Krajmalnik-Brown, Rosa (Committee member) / Sommerfeld, Milton (Committee member) / Arizona State University (Publisher)
Created2010
Description
With global warming becoming a more serious problem and mankind's alarming dependency on fossil fuels, the need for a sustainable and environmentally friendly fuel source is becoming more important. Biofuels produced from photosynthetic microorganisms like algae or cyanobacteria offer a carbon neutral replacement for petroleum fuel sources; however, with the technology and information available today, the amount of biomass that would need to be produced is not economically feasible. In this work, I examined a possible factor impacting the growth of a model cyanobacterium, Synechocystis sp. PCC6803, which is heterotrophic bacteria communities accompanying the cyanobacteria. I experimented with three variables: the type of heterotrophic bacteria strain, the initial concentration of heterotrophic bacteria, and the addition of a carbon source (glucose) to the culture. With experimental information, I identified if given conditions would increase Synechocystis growth and thus increase the yield of biomass. I found that under non-limiting growth conditions, heterotrophic bacteria do not significantly affect the growth of Synechocystis or the corresponding biomass yield. The initial concentration of heterotrophic bacteria and the added glucose also did not affect the growth of Synechocystis. I did see some nutrient recycling from the heterotrophic bacteria as the phosphate levels in the growth medium were depleted, which was apparent from prolonged growth phase and higher levels of reactive phosphate in the media.
ContributorsCahill, Brendan Robert (Author) / Rittmann, Bruce (Thesis director) / Krajmalnik-Brown, Rosa (Committee member) / W. P. Carey School of Business (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
Inhibition by ammonium at concentrations above 1000 mgN/L is known to harm the methanogenesis phase of anaerobic digestion. We anaerobically digested swine waste and achieved steady state COD-removal efficiency of around 52% with no fatty-acid or H[subscript 2] accumulation. As the anaerobic microbial community adapted to the gradual increase of total ammonia-N (NH[subscript 3]-N) from 890 ± 295 to 2040 ± 30 mg/L, the Bacterial and Archaeal communities became less diverse. Phylotypes most closely related to hydrogenotrophic Methanoculleus (36.4%) and Methanobrevibacter (11.6%), along with acetoclastic Methanosaeta (29.3%), became the most abundant Archaeal sequences during acclimation. This was accompanied by a sharp increase in the relative abundances of phylotypes most closely related to acetogens and fatty-acid producers (Clostridium, Coprococcus, and Sphaerochaeta) and syntrophic fatty-acid Bacteria (Syntrophomonas, Clostridium, Clostridiaceae species, and Cloacamonaceae species) that have metabolic capabilities for butyrate and propionate fermentation, as well as for reverse acetogenesis. Our results provide evidence countering a prevailing theory that acetoclastic methanogens are selectively inhibited when the total ammonia-N concentration is greater than ~1000 mgN/L. Instead, acetoclastic and hydrogenotrophic methanogens coexisted in the presence of total ammonia-N of ~2000 mgN/L by establishing syntrophic relationships with fatty-acid fermenters, as well as homoacetogens able to carry out forward and reverse acetogenesis.
ContributorsEsquivel Elizondo, Sofia (Author) / Parameswaran, Prathap (Author) / Delgado, Anca (Author) / Maldonado, Juan (Author) / Rittmann, Bruce (Author) / Krajmalnik-Brown, Rosa (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor) / Ira A. Fulton Schools of Engineering (Contributor) / School of Sustainable Engineering and the Built Environment (Contributor)
Created2016-08-11
Description
The purpose of this thesis is to compare ecolabeling to conservation easements for facilitating multi-use land between food production and conservation. Biodiversity has been on the decline as human agriculture uses more land. According to Encyclopedia Britannica “Half of the world’s habitable land (some 51 million square km [19.7 million square miles]) has been converted to agriculture, and some 77 percent of agricultural land (some 40 million square km [15.4 million square miles]) is used for grazing by cattle, sheep, goats, and other livestock. This massive conversion of forests, wetlands, grasslands, and other terrestrial ecosystems has produced a 60 percent decline (on average) in the number of vertebrates worldwide since 1970”(Rafferty 2010). The purpose of this paper is to explore ways individual landowners and private businesses can continue to operate profitably on their land while reversing the harmful loss to biodiversity observed in the past 50 years. Two of the most popular methods of achieving conservation on workable land are ecolabeling and conservation easements.
ContributorsWilcox, Christopher James (Author) / Leonard, Brian (Thesis director) / Schoon, Michael (Committee member) / Dean, W.P. Carey School of Business (Contributor) / Department of Supply Chain Management (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
We studied the microbial community structure of pilot two-stage membrane biofilm reactors (MBfRs) designed to reduce nitrate (NO[subscript 3]–) and perchlorate (ClO[subscript 4]–) in contaminated groundwater. The groundwater also contained oxygen (O[subscript 2]) and sulfate (SO[2 over 4]–), which became important electron sinks that affected the NO[subscript 3]– and ClO[subscript 4]– removal rates. Using pyrosequencing, we elucidated how important phylotypes of each “primary” microbial group, i.e., denitrifying bacteria (DB), perchlorate-reducing bacteria (PRB), and sulfate-reducing bacteria (SRB), responded to changes in electron-acceptor loading. UniFrac, principal coordinate analysis (PCoA), and diversity analyses documented that the microbial community of biofilms sampled when the MBfRs had a high acceptor loading were phylogenetically distant from and less diverse than the microbial community of biofilm samples with lower acceptor loadings. Diminished acceptor loading led to SO[2 over 4]– reduction in the lag MBfR, which allowed Desulfovibrionales (an SRB) and Thiothrichales (sulfur-oxidizers) to thrive through S cycling. As a result of this cooperative relationship, they competed effectively with DB/PRB phylotypes such as Xanthomonadales and Rhodobacterales. Thus, pyrosequencing illustrated that while DB, PRB, and SRB responded predictably to changes in acceptor loading, a decrease in total acceptor loading led to important shifts within the “primary” groups, the onset of other members (e.g., Thiothrichales), and overall greater diversity.
ContributorsOntiveros-Valencia, Aura (Author) / Tang, Youneng (Author) / Zhao, Heping (Author) / Friese, David (Author) / Overstreet, Ryan (Author) / Smith, Jennifer (Author) / Evans, Patrick (Author) / Rittmann, Bruce (Author) / Krajmalnik-Brown, Rosa (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2014-07-01
Description
The issue of wild horse management in the American West has become prevalent in the media recently and management strategies are often criticized and opposed by the public. Horses have been a core feature of American history and culture nearly since the colonization of the western frontier, and popular media such as television and movies paint a romantic but often unrealistic picture of wild horses. Land management agencies must balance limited resources with an ever-growing wild horse population in order to properly manage public land so that it retains its ecological integrity and is still able to be used by multiple stakeholders, and they also must endure public criticism throughout the process. I used a photo elicitation survey to gather responses to photographic images of wild horses and determine how the public feels about wild horse management, given that horses are seen as a symbol of freedom and the American West. It was revealed that people who are unfamiliar with the issue still have opinions about how the horses should be managed, and these opinions often mirror what can be found in popular media.
ContributorsDuran, Kiana Alexis (Author) / Minteer, Ben (Thesis director) / Schoon, Michael (Thesis director) / Murphree, Julie (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
As human populations continue to expand, interactions with wildlife are expected to increase due to destruction of land and global climate change threatening native habitats. Established areas of protection are becoming essential to species survival and biodiversity protection. National Parks (NP) are a globally ubiquitous method employed to protect wildlife and habitats. Often NPs are mosaics of relatively small protected areas in a “sea” of human-dominated landscapes, and these remaining habitat “islands” are becoming essential to preventing species extinction. However, the establishment of a NP can lead to increased human-wildlife conflicts (HWC) and disenfranchisement of local communities, particularly along their borders. We conducted semi-structured interviews in six different countries to better understand the nature of HWCs at the borders of major NPs: (1) Khao Yai NP, Thailand; (2) Myall Lakes NP, Australia; (3) Chitwan NP, Nepal; (4) Kruger NP, South Africa; (5) Chingaza NP, Colombia, and (6) Yellowstone NP, United States. We evaluated affinity to wildlife, perception of conflicts, management success, and potential solutions at each park to better understand the global nature of HWCs.We also evaluated these data in relationship to the Human Development Index (HDI) to determine if there was a correlation between development and conflict issues. We found the intrinsic value of wildlife to not markedly differ between countries. Conflict was perceived as higher in the United States and Australia but was known to be of greater intensity in Nepal and South Africa. Management of NPs was well-regarded with a slight decrease from less-developed countries to more-developed countries, with solutions that were creative and unique to each region. Results appeared to be related to shifting baselines between countries and also to equivalency in a cross-cultural assessment. When these theories are taken into account, the complexity of HWCs globally is better understood. As our world continues to expand and NPs become some of the only contiguous native habitat and refuges for wildlife, it is important to understand the complex relationships occurring at the interface between natural and human communities and to explore effective solutions to these problems.
ContributorsRagan, Kinley Ann (Author) / Schoon, Michael (Thesis director) / Schipper, Jan (Committee member) / Senko, Jesse (Committee member) / School of Life Sciences (Contributor, Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Human activities around the world are threatening scores of wildlife species, pushing them closer to extinction. In order to address what many conservationists view as a global biodiversity crisis, it is vital that more people are inspired to care about wild animals and motivated to act in ways that help protect them. The up-close experiences and personal connections that people form with wild animals in zoos accredited by the Association of Zoos and Aquariums (AZA) or the World Association of Zoos and Aquariums (WAZA) can help achieve this. However, it is not very well understood how different types of encounters within these zoos may inspire conservation mindedness and pro-environmental behaviors. During this thesis project, surveys were conducted at the AZA-accredited Arizona Center for Nature Conservation/Phoenix Zoo to understand how interactive, hands-on animal experiences within zoos differ from passively viewing zoo animals when it comes to inspiring people to care about conservation. The Phoenix Zoo is home to two different species of giraffes, and guests can view them from the front of the Savanna Exhibit. Guests can also participate in the Giraffe Encounter, which is a much more interactive, hands-on experience. After surveying guests at both locations, the results showed that fewer people at the Giraffe Encounter responded that they often engage in pro-environmental behaviors. This may indicate that the people who participated in the Giraffe Encounter came to the zoo more for recreation and entertainment than to learn about wildlife. Despite this, more people learned something new about nature or conservation at the Giraffe Encounter than they did at the Savanna Exhibit. On average, guests also felt that the Giraffe Encounter motivated them to learn more about how to help animals in the wild than the Savanna Exhibit did. Overall, there is a strong correlation between having an interactive, hands-on experience with a zoo animal and caring more about wildlife conservation. However, more research still needs to be done in order to conclusively provide evidence for causation.
ContributorsBurgess, Christa Noell (Author) / Schoon, Michael (Thesis director) / Minteer, Ben (Committee member) / Allard, Ruth (Committee member) / School of Life Sciences (Contributor) / School of Sustainability (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
Description
This paper covers the wild horse overpopulation case study at the Salt River in Arizona, exploring how Traditional Ecological Knowledge (TEK) might help foster solutions to a lengthy and heated controversy about how to manage wild horses and burros on the rangeland. Fikret Berke's Sacred Ecology defines traditional ecological knowledge as, "a cumulative body of knowledge, practice, and belief evolving by adaptive processes and handed down through generations by cultural transmission, about the relationship of living beings (including humans) with one another and with their environment," (Berkes, 3). In contrast to current management strategies, TEK utilizes knowledge that comes from direct experience and intuitive knowing, rather than science-based, techno-rational streams of knowledge. Drawing on three modern sustainability concepts that support and stem from TEK, including: everything is connected, complex solutions can further complicate problems and diversity as a key to resilience, this paper sets forth a number of specific solutions to be considered moving forward, guided by the wisdom of TEK.
ContributorsLyford, Rebecca (Author) / Schoon, Michael (Thesis director) / Murphey, Julia (Committee member) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05