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- All Subjects: Ecology
- Creators: Childers, Daniel L.
- Creators: McGraw, Kevin J.
- Creators: School of Sustainability
- Resource Type: Text
- Status: Published
Description
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
Description
Defines the concept of the arcology as conceived by architect Paolo Soleri. Arcology combines "architecture" and "ecology" and explores a visionary notion of a self-contained urban community that has agricultural, commercial, and residential facilities under one roof. Two real-world examples of these projects are explored: Arcosanti, AZ and Masdar City, Abu Dhabi, UAE. Key aspects of the arcology that could be applied to an existing urban fabric are identified, such as urban design fostering social interaction, reduction of automobile dependency, and a development pattern that combats sprawl. Through interviews with local representatives, a holistic approach to applying arcology concepts to the Phoenix Metro Area is devised.
ContributorsSpencer, Sarah Anne (Author) / Manuel-Navarrete, David (Thesis director) / Salon, Deborah (Committee member) / Barrett, The Honors College (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / School of Sustainability (Contributor)
Created2015-05
Description
The origin and function of color in animals has been a subject of great interest for taxonomists and ecologists in recent years. Coloration in animals is useful for many important functions like species identification, camouflage and understanding evolutionary relationships. Quantitative measurements of color signal and patch size in mammals, birds and reptiles, to name a few are strong indicators of sexual selection cues and individual health. These measurements provide valuable insights into the impact of environmental conditions on habitat and breeding of mammals, birds and reptiles. Recent advances in the area of digital cameras and sensors have led to a significant increase in the use of digital photography as a means of color quantification in animals. Although a significant amount of research has been conducted on ways to standardize image acquisition conditions and calibrate cameras for use in animal color quantification, almost no work has been done on designing automated methods for animal color quantification. This thesis presents a novel perceptual"–"based framework for the automated extraction and quantification of animal coloration from digital images with slowly varying (almost homogenous) background colors. This implemented framework uses a combination of several techniques including color space quantization using a few dominant colors, foreground"–"background identification, Bayesian classification and mixture Gaussian modelling of conditional densities, edge"–"enhanced model"–"based classification and Saturation"–"Brightness quantization to extract the colored patch. This approach assumes no prior information about the color of either the subject or the background and also the position of the subject in the image. The performance of the proposed method is evaluated for the plumage color of the wild house finches. Segmentation results obtained using the implemented framework are compared with manually scored results to illustrate the performance of this system. The segmentation results show a high correlation with manually scored images. This novel framework also eliminates common problems in manual scoring of digital images such as low repeatability and inter"–"observer error.
ContributorsBorkar, Tejas (Author) / Karam, Lina J (Thesis advisor) / Li, Baoxin (Committee member) / McGraw, Kevin J. (Committee member) / Arizona State University (Publisher)
Created2013
Description
Colorful ornaments in animals often serve as sexually selected signals of quality. While pigment-based colors are well-studied in these regards, structural colors that result from the interaction of light with photonic nanostructures are comparatively understudied in terms of their consequences in social contexts, their costs of production, and even the best way to measure them. Iridescent colors are some of the most brilliant and conspicuous colors in nature, and I studied the measurement, condition-dependence, and signaling role of iridescence in Anna's hummingbirds (Calypte anna). While most animal colors are easily quantified using well-established spectrophotometric techniques, the unique characteristics of iridescent colors present challenges to measurement and opportunities to quantify novel color metrics. I designed and tested an apparatus for careful control and measurement of viewing geometry and highly repeatable measurements. These measurements could be used to accurately characterize individual variation in iridescent Anna's hummingbirds to examine their condition-dependence and signaling role. Next, I examined the literature published to date for evidence of condition-dependence of structural colors in birds. Using meta-analyses, I found that structural colors of all three types - white, ultra-violet/blue, and iridescence - are significantly condition-dependent, meaning that they can convey information about quality to conspecifics. I then investigated whether iridescent colors were condition-dependent in Anna's hummingbirds both in a field correlational study and in an experimental study. Throughout the year, I found that iridescent feathers in both male and female Anna's hummingbirds become less brilliant as they age. Color was not correlated with body condition in any age/sex group. However, iridescent coloration in male Anna's hummingbirds was significantly affected by experimental protein in the diet during feather growth, indicating that iridescent color may signal diet quality. Finally, I examined how iridescent colors were used to mediate social competitions in male and female Anna's hummingbirds. Surprisingly, males that were less colorful won significantly more contests than more colorful males, and colorful males received more aggression. Less colorful males may be attempting to drive away colorful neighbors that may be preferred mates. Female iridescent ornament size and color was highly variable, but did not influence contest outcomes or aggression.
ContributorsMeadows, Melissa (Author) / McGraw, Kevin J. (Thesis advisor) / Rutowski, Ronald L (Committee member) / Sabo, John L (Committee member) / Alcock, John (Committee member) / Deviche, Pierre (Committee member) / Arizona State University (Publisher)
Created2012
Description
Differences between males and females can evolve through a variety of mechanisms, including sexual and ecological selection. Because coloration is evolutionarily labile, sexually dichromatic species are good models for understanding the evolution of sex differences. While many jumping spiders exhibit diverse and brilliant coloration, they have been notably absent from such studies. In the genus Habronattus, females are drab and cryptic while males are brilliantly colored, displaying some of these colors to females during elaborate courtship dances. Here I test multiple hypotheses for the control and function of male color. In the field, I found that Habronattus males indiscriminately court any female they encounter (including other species), so I first examined the role that colors play in species recognition. I manipulated male colors in H. pyrrithrix and found that while they are not required for species recognition, the presence of red facial coloration improves courtship success, but only if males are courting in the sun. Because light environment affects transmission of color signals, the multi-colored displays of males may facilitate communication in variable and unpredictable environments. Because these colors can be costly to produce and maintain, they also have the potential to signal reliable information about male quality to potential female mates. I found that both red facial and green leg coloration is condition dependent in H. pyrrithrix and thus has the potential to signal quality. Yet, surprisingly, this variation in male color does not appear to be important to females. Males of many Habronattus species also exhibit conspicuous markings on the dorsal surface of their abdomens that are not present in females and are oriented away from females during courtship. In the field, I found that these markings are paired with increased leg-waving behavior in a way that resembles the pattern and behavior of wasps; this may provide protection by exploiting the aversions of predators. My data also suggest that different activity levels between the sexes have placed different selection pressures on their dorsal color patterns. Overall, these findings challenge some of the traditional ways that we think about color signaling and provide novel insights into the evolution of animal coloration.
ContributorsTaylor, Lisa Anne (Author) / McGraw, Kevin J. (Thesis advisor) / Clark, David L. (Committee member) / Johnson, James C. (Committee member) / Alcock, John (Committee member) / Rutowski, Ronald L (Committee member) / Arizona State University (Publisher)
Created2012
Description
This paper explores the relationship between wildfire management and the consideration of ecological and environmental concerns in Arizona. To get a proper perspective on the current state of wildfire management in Arizona, information on two wildfire management programs, the Four Forests Restoration Initiative and FireScape, was researched and analyzed, as well as contemporary fire policy, a history of wildfire in Arizona, and two recent fires in Sedona, AZ. The two fires in Sedona, the Brins Fire of 2006 and the Slide Fire of 2014, act as a focal point for this ecological management transition, as even within an 8-year period, we can see the different ways the two fires were managed and the transition to a greater ecological importance in management strategies. These all came together to give a full spectrum for the factors that have led to more ecologically-prominent wildfire management strategies in Arizona.
ContributorsGeorge-Sills, Dylan (Author) / Pyne, Stephen (Thesis director) / Hirt, Paul (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Sustainability (Contributor)
Created2015-05
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 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
Description
There are three known materials that readily undergo fission, allowing their use as a base for nuclear fuel: uranium-235, a naturally-occurring but uncommon isotope; plutonium, created from irradiated natural uranium; and uranium-233, produced from thorium. Of the three, uranium-235 and plutonium feature heavily in the modern nuclear industry, while uranium-233 and the thorium fuel cycle have failed to have significant presence in the field. Historically, nuclear energy development in the United States, and thorium development in particular, has been tied to the predominant societal outlook on the field, and thorium was only pursued seriously as an option during a period when nuclear energy was heavily favored, and resources seemed scarce. Recently, thorium-based energy has been experiencing a revival in interest in response to pollution concerns regarding fossil fuels. While public opinion is still wary of uranium, thorium-based designs could reduce reliance on fossil fuels while avoiding traditional drawbacks of nuclear energy. The thorium fuel cycle is more protected against proliferation, but is also much more expensive than the uranium-plutonium cycle in a typical reactor setup. Liquid-fueled molten salt reactor designs, however, bypass the prohibitive expense of U-233 refabrication by avoiding the stage entirely, keeping the chain reaction running with nothing but thorium input required. MSRs can use any fissile material as fuel, and are relatively safe to operate, due to passive features inherent to the design.
ContributorsGalbiati, Joseph Nicco (Author) / Martin, Thomas (Thesis director) / Foy, Joseph (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor)
Created2014-05
Description
Human activity produces ambient noise that potentially alters species’ abilities to communicate with each other—among other impacts. Given that birds are known to be sensitive to structural changes in habitat and highly communicative through sound, it is beneficial to understand how changing acoustic ecologies and ambient noise impact birds’ ability to communicate in their respective environments. In this study, mockingbird calls from an urban, desert, and intermediate study site were recorded and analyzed for differences in acoustic properties. Acoustic properties such as frequency and amplitude differed significantly across sites as it was determined that mockingbirds in urban areas increase both the peak frequency and amplitude of their calls in order to communicate. This study identifies what these changes in acoustic properties mean in relation to the survival and conservation of birds and concludes with recommendations for novel research.
ContributorsReynolds, Bailey Susana (Author) / Pearson, David (Thesis director) / Walters, Molina (Committee member) / School of Sustainability (Contributor) / School of Life Sciences (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Constructed treatment wetlands (CTW) are being increasingly utilized in urbanized areas as a cost-effective and environmentally-friendly method for treating wastewater. CTWs can be especially useful for urban areas in aridland environments because they facilitate the reuse of water during water shortages. In my study, I determined the rates at which the aboveground and belowground emergent macrophytes sequestered nitrogen in a 42 ha aridland CTW in Phoenix, Arizona, USA. To do so, I measured foliar nitrogen content in aboveground and belowground biomass of three plant species groups (Typha latifolia + Typha domingensis, Schoenoplectus acutus + Schoenoplectus tabernaemontani, and Schoenoplectus californicus). Using these data, I calculated aboveground and belowground nitrogen budgets for the three species groups annually from 2011 to 2018.
Aboveground nitrogen content showed a maximum in 2011, decreasing until 2015, increasing again until 2017, and dropping in 2018; belowground nitrogen content showed the opposite temporal trend. Because foliar nitrogen content was assumed to be relatively constant over time, my data suggested that belowground nitrogen content increased between 2011 and 2015 and decreased between 2015 and 2017. Aboveground nitrogen content underwent fluctuations due to fluctuations in aboveground biomass. This occurred due to ‘thatching’, or events of widespread toppling of large macrophyte stands. The ratio of aboveground to belowground biomass can vary widely in the same CTW. My findings suggested that managing senesced aboveground plant material in CTWs may optimize the CTW’s ability to sequester nitrogen. Further research is needed to determine the best management strategies, as well as its possible implications.
Aboveground nitrogen content showed a maximum in 2011, decreasing until 2015, increasing again until 2017, and dropping in 2018; belowground nitrogen content showed the opposite temporal trend. Because foliar nitrogen content was assumed to be relatively constant over time, my data suggested that belowground nitrogen content increased between 2011 and 2015 and decreased between 2015 and 2017. Aboveground nitrogen content underwent fluctuations due to fluctuations in aboveground biomass. This occurred due to ‘thatching’, or events of widespread toppling of large macrophyte stands. The ratio of aboveground to belowground biomass can vary widely in the same CTW. My findings suggested that managing senesced aboveground plant material in CTWs may optimize the CTW’s ability to sequester nitrogen. Further research is needed to determine the best management strategies, as well as its possible implications.
ContributorsCrane, Austin Matthew (Author) / Childers, Daniel (Thesis director) / Sanchez, Christopher (Committee member) / School of Life Sciences (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05