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• 1741. [Article] Population Genetics of American Pika (Ochotona princeps) : Investigating Gene Flow and Genetic Diversity Across Multiple, Complex Landscapes

  American pikas (Ochotona princeps) are considered an indicator species of climate change. Adaptations for cold climates and active winters make pikas particularly sensitive to increasing temperatures. ...

  Citation × Citation Citation Abstract Copy Title: Population Genetics of American Pika (Ochotona princeps) : Investigating Gene Flow and Genetic Diversity Across Multiple, Complex Landscapes Author: Castillo, Jessica A. American pikas (Ochotona princeps) are considered an indicator species of climate change. Adaptations for cold climates and active winters make pikas particularly sensitive to increasing temperatures. This, combined with evidence that multiple historically occupied populations have been extirpated within the past century, contributed to American pikas becoming a focal species for climate change research. This dissertation is primarily the product of a collaboration among the National Parks Service and multiple academic institutions whose principal goal was to assess the vulnerability of the American pika within eight national parks representing a variety of habitat types and environmental conditions. While much of the previous climate change-related research on American pikas has focused on how climate affects occupancy, this work sought to establish how landscape characteristics and climate may interact and influence dispersal, population connectivity, and ultimately population vulnerability or resilience. I addressed these questions using population and landscape genetics approaches within nine national parks, two national wildlife refuges, and a national forest. American pikas represent one of the best described mammalian metapopulation systems. They are restricted to rocky habitats, such as talus and lava, which are frequently patchily distributed on the landscape, both at the local and regional scales. Functional connectivity, the combination of habitat configuration and an organism’s ability to move through the landscape, is essential for maintaining robust genetic populations. This is particularly true within metapopulations which, by definition, rely on dispersal of individuals among habitat patches for overall long-term stability. In Chapters 1 and 2, I used a landscape genetics approach to identify features that either promote or inhibit dispersal of American pikas. There has been significant debate over the past few years about the best statistical approaches within landscape genetics and the appropriateness of certain methods in particular. In Chapter 1, I used Crater Lake National Park as a test case to evaluate the effectiveness of Mantel and partial Mantel tests in a causal modeling framework to correctly identify underlying landscape variables (e.g., topography, aspect, water barriers) and their effect on gene flow. I demonstrated, through simulations, that this approach was able to correctly identify the landscape variables, but not precisely the magnitude of their effect on gene flow. I concluded that while results need to be interpreted with caution, this method was effective for identifying which variables are important in shaping functional connectivity. In Chapter 2, I applied the causal modeling approach from Chapter 1 to seven additional study sites. I identified a general trend that south-west facing aspects pose greater resistance to dispersal than north and east-facing aspects, suggesting that exposure to high temperatures may limit dispersal in American pikas. I also found that amount and configuration of habitat (i.e., rocky substrate) influenced the degree to which other landscape variables impact dispersal. I then applied the models of landscape resistance to investigate habitat patch connectivity within each site using a graph theoretic approach. This allowed me to assess overall patch connectivity, as well as identify specific patches and areas within study sites that are particularly important for maintaining functional connectivity, or in contrast, at risk of becoming isolated. Functional connectivity is an important component when assessing population vulnerability because it describes the ability of genetic material to flow through the landscape. A loss of gene flow can lead to isolation of population segments, reduction of effective population size, loss of genetic diversity and subsequent erosion of evolutionary potential, and ultimately metapopulation collapse. However, other factors including habitat area and quality, affect effective population size and population stability. Genetic diversity is the material upon which evolution acts. In the face of rapid environmental change, species must either shift their range in order to track their ecological niche, or adapt in situ to the new environment. The former strategy requires sufficient available habitat as well as dispersal ability, which is unlikely for American pikas. Genetic diversity, therefore, is an important indicator of long-term population viability. In Chapter 3, I quantified genetic diversity within thirteen study sites and investigated the relationship between genetic diversity and environmental variables related to climate as well as habitat configuration and quality. As expected, habitat area was important at both the local and regional scales. Temperature was also a significant predictor of genetic diversity, with hotter sites having lower genetic diversity. However, and somewhat surprisingly, precipitation was a better predictor of genetic diversity than temperature, with sites receiving moderate levels of precipitation having higher genetic diversity. I also compared population differentiation among study sites and identified sites that are particularly distinct. In the process of the above analyses, I also identified a previously undescribed contact zone between the northern and southern Rocky Mountain genetic lineages, recognized as separate subspecies, within Rocky Mountain National Park. Climate change is predicted to affect habitat quality and landscape permeability, both of which have detectable genetic consequences. In Chapter 4, I quantified genetic diversity and structure within two study sites, Yosemite and Lassen Volcanic National Parks, from two sampling periods separated by approximately a century in time. I extracted DNA from historic study skins housed in the University of California Berkeley Museum of Vertebrate Zoology (MVZ) and compared multilocus microsatellite genotypes to those generated from modern fecal and tissue samples. Additionally, the historic survey data, including specimens, field journals, and other artifacts, were used in a series of systematic resurveys and subsequent species distribution modelling by other researchers. The nature of national parks as protected areas affords the opportunity to isolate the effects of climate change to a greater degree than other areas that have also experienced significant land use changes. I found no evidence for a change in genetic diversity within these two sites, consistent with observations from other studies that occupancy has remained relatively stable. I did find some evidence suggesting increasing population differentiation, potentially as a result of eroding landscape permeability. These results provide an important baseline for comparison with other sites, as well as reference points for future genetic monitoring of these populations. In Chapter 5, I provide general synthesis and conclusions, as well as considerations for future research. Title: Population Genetics of American Pika (Ochotona princeps) : Investigating Gene Flow and Genetic Diversity Across Multiple, Complex Landscapes Author: Castillo, Jessica A. American pikas (Ochotona princeps) are considered an indicator species of climate change. Adaptations for cold climates and active winters make pikas particularly sensitive to increasing temperatures. This, combined with evidence that multiple historically occupied populations have been extirpated within the past century, contributed to American pikas becoming a focal species for climate change research. This dissertation is primarily the product of a collaboration among the National Parks Service and multiple academic institutions whose principal goal was to assess the vulnerability of the American pika within eight national parks representing a variety of habitat types and environmental conditions. While much of the previous climate change-related research on American pikas has focused on how climate affects occupancy, this work sought to establish how landscape characteristics and climate may interact and influence dispersal, population connectivity, and ultimately population vulnerability or resilience. I addressed these questions using population and landscape genetics approaches within nine national parks, two national wildlife refuges, and a national forest. American pikas represent one of the best described mammalian metapopulation systems. They are restricted to rocky habitats, such as talus and lava, which are frequently patchily distributed on the landscape, both at the local and regional scales. Functional connectivity, the combination of habitat configuration and an organism’s ability to move through the landscape, is essential for maintaining robust genetic populations. This is particularly true within metapopulations which, by definition, rely on dispersal of individuals among habitat patches for overall long-term stability. In Chapters 1 and 2, I used a landscape genetics approach to identify features that either promote or inhibit dispersal of American pikas. There has been significant debate over the past few years about the best statistical approaches within landscape genetics and the appropriateness of certain methods in particular. In Chapter 1, I used Crater Lake National Park as a test case to evaluate the effectiveness of Mantel and partial Mantel tests in a causal modeling framework to correctly identify underlying landscape variables (e.g., topography, aspect, water barriers) and their effect on gene flow. I demonstrated, through simulations, that this approach was able to correctly identify the landscape variables, but not precisely the magnitude of their effect on gene flow. I concluded that while results need to be interpreted with caution, this method was effective for identifying which variables are important in shaping functional connectivity. In Chapter 2, I applied the causal modeling approach from Chapter 1 to seven additional study sites. I identified a general trend that south-west facing aspects pose greater resistance to dispersal than north and east-facing aspects, suggesting that exposure to high temperatures may limit dispersal in American pikas. I also found that amount and configuration of habitat (i.e., rocky substrate) influenced the degree to which other landscape variables impact dispersal. I then applied the models of landscape resistance to investigate habitat patch connectivity within each site using a graph theoretic approach. This allowed me to assess overall patch connectivity, as well as identify specific patches and areas within study sites that are particularly important for maintaining functional connectivity, or in contrast, at risk of becoming isolated. Functional connectivity is an important component when assessing population vulnerability because it describes the ability of genetic material to flow through the landscape. A loss of gene flow can lead to isolation of population segments, reduction of effective population size, loss of genetic diversity and subsequent erosion of evolutionary potential, and ultimately metapopulation collapse. However, other factors including habitat area and quality, affect effective population size and population stability. Genetic diversity is the material upon which evolution acts. In the face of rapid environmental change, species must either shift their range in order to track their ecological niche, or adapt in situ to the new environment. The former strategy requires sufficient available habitat as well as dispersal ability, which is unlikely for American pikas. Genetic diversity, therefore, is an important indicator of long-term population viability. In Chapter 3, I quantified genetic diversity within thirteen study sites and investigated the relationship between genetic diversity and environmental variables related to climate as well as habitat configuration and quality. As expected, habitat area was important at both the local and regional scales. Temperature was also a significant predictor of genetic diversity, with hotter sites having lower genetic diversity. However, and somewhat surprisingly, precipitation was a better predictor of genetic diversity than temperature, with sites receiving moderate levels of precipitation having higher genetic diversity. I also compared population differentiation among study sites and identified sites that are particularly distinct. In the process of the above analyses, I also identified a previously undescribed contact zone between the northern and southern Rocky Mountain genetic lineages, recognized as separate subspecies, within Rocky Mountain National Park. Climate change is predicted to affect habitat quality and landscape permeability, both of which have detectable genetic consequences. In Chapter 4, I quantified genetic diversity and structure within two study sites, Yosemite and Lassen Volcanic National Parks, from two sampling periods separated by approximately a century in time. I extracted DNA from historic study skins housed in the University of California Berkeley Museum of Vertebrate Zoology (MVZ) and compared multilocus microsatellite genotypes to those generated from modern fecal and tissue samples. Additionally, the historic survey data, including specimens, field journals, and other artifacts, were used in a series of systematic resurveys and subsequent species distribution modelling by other researchers. The nature of national parks as protected areas affords the opportunity to isolate the effects of climate change to a greater degree than other areas that have also experienced significant land use changes. I found no evidence for a change in genetic diversity within these two sites, consistent with observations from other studies that occupancy has remained relatively stable. I did find some evidence suggesting increasing population differentiation, potentially as a result of eroding landscape permeability. These results provide an important baseline for comparison with other sites, as well as reference points for future genetic monitoring of these populations. In Chapter 5, I provide general synthesis and conclusions, as well as considerations for future research. Close

• 1742. [Article] Urban natural parks in Portland : nature, networks, and community health

  Three trends are occurring today in the United States which inspired this research. First, America is growing increasingly urbanized. Today, more Americans are living in cities than in rural environments, ...

  Citation × Citation Citation Abstract Copy Title: Urban natural parks in Portland : nature, networks, and community health Author: Baur, Joshua W. R. Three trends are occurring today in the United States which inspired this research. First, America is growing increasingly urbanized. Today, more Americans are living in cities than in rural environments, and this pattern is predicted to continue for the foreseeable future. Urban living has benefits, but there are also challenges for city residents including pollution, traffic, and crime. As social scientists, we need to improve our understanding of urban dwellers' relationship with their natural environment just as biophysical scientists are focusing more and more on the impacts of urban development on the natural world. Second, Americans are spending less time recreating outdoors. There has been a documented decline of participation in nature-based recreation, likely being replaced by an increase in use of electronic media during people's leisure time. Less contact with nature has consequences for people, perhaps especially for city dwellers who spend the majority of their time surrounded by the built environment of concrete and asphalt. It is likely that reliance on electronic entertainment has played a substantial role in decreasing amounts of physical activity. Lastly, Americans are becoming more sedentary. Today, the number of Americans who report getting no physical activity is about equal to the number who report getting regular physical exercise during their free time. Rising rates of obesity for adults and children in the U.S. have raised considerable concerns among medical and public policy professionals. The purpose of this research was to examine how small-scale urban nature parks are affecting city residents in Portland, OR. I looked at three elements of Portland residents' relationship with urban nature parks. First, I looked at whether there was an association between individual physical and psychological health and park use. Prior research has revealed that people who spend time recreating outdoors tend to be more physically active than people who do not. These observed higher levels of physical activity are associated with improved physical health. Time in nature settings has also demonstrated a positive effect on psychological well-being, such as reduced anxiety and improved ability to concentrate. Second, I examined whether having a nature park in their community had an effect on Portland residents' sense of neighborhood health. Previous research suggests that having natural areas in urbanized areas directly contributes to city residents' sense of a stronger, healthier community. Green space in cities has been associated with not only higher levels of reported satisfaction with the neighborhood, but also with higher property values, and with higher levels of retail spending. Third, I employed a social psychological model of attitude formation to evaluate Portland residents' attitudes about their nature parks. Attitudes are particularly important for natural resource managers to understand and account for in policy decisions since management of natural resources often engages the public's sense of personal freedoms and concerns over government regulations. Furthermore, because people in cities are so closely in contact with urban green space on a regular basis, inclusive and responsive policy requires that managers take account of public attitudes. I collected the data relating to these three elements of the relationship between urban residents and their nature parks in Portland because it is the largest city in Oregon. I obtained the data through a general population survey, randomly distributed to residents in the Portland metropolitan area during the fall of 2010. I conducted customary social science statistical analysis, including linear regression, to assess the relationship between Portland nature parks and personal and community health. To evaluate my sample's attitudes, I used the tripartite model of attitude formation originally developed in social psychology research. Because I was working with latent factors of attitude formation, I used structural equation modeling to assess the relationship of the observed variables to their latent factors, and the relationship among the latent factors. My results largely agree with those of other researchers, though I approached the question of physical health and nature recreation slightly differently. For my work on physical health, rather than ask about physical activity and infer health outcomes, I asked directly about physical health. I tested two hypotheses. One hypothesis was that there would be a positive association between self-reported physical health and park use, and the other tested for a positive association between park use and psychological health. My hypothesis for the physical health-parks relationship was partially supported. I tested two physical health variables, and found that one, which described overall health, did reveal a statistically significant relationship to park use. The other, relating to role limitations due to physical health problems, did not have a significant relationship to park use. My second hypothesis asserted that there would be a positive relationship between psychological health and park user status. This hypothesis was not supported, but I did find indications of an association between psychological health and park use. The second element of the relationship between city residents and urban nature parks related to neighborhood health. My results from this analysis were consistent with prior research findings which tend to support a positive association. I tested whether parks close by respondents homes (a fifteen to twenty minute walk), and parks farther away (no more than a ten minute drive away from home) were positively associated with self-reported neighborhood health. I found that both levels of proximity were positively associated with perceptions of neighborhood health. Because prior research suggests that one of the ways that neighborhood green spaces promote stronger communities is through the social interactions that occur in parks among neighbors, I also tested whether park-related social interaction was positively associated with community health ratings. In testing for a mediating effect of social interaction on the relationship between parks and neighborhood health, I found that park-related social interaction had a partial mediating effect on neighborhood health ratings for both parks within walking distance and within driving distance. In testing for moderation, I found that the moderation effect of social interaction was present only for parks within walking distance. The third and final element of the relationship between urban nature parks and city dwellers was attitudes about urban nature parks. I employed a model of attitude formation originally proposed in the social psychology literature. The tripartite model argues that an attitude is formed through three precursors: the cognitive, the affective, and the behavioral components. I also included an additional variable for social networks which I proposed would act as a moderating variable on the relationship between the other components and park attitude. My results for the entire, combined sample of both park users and nonusers indicated that both the cognitive factor and the affective factor have a significant association with attitude formation, while the behavioral component did not. The model for the combined sample also showed that social networks had a statistically significant, inverse relationship with attitudes. I conducted a test for attitude differences between groups (users and nonusers), and found a statistically significant difference. I also tested for a moderating effect of social networks on the other attitude formation components, but that relationship was not supported. Finally, I conducted comparisons between the two groups to assess any differences in the attitude components between users and nonusers. Side-by-side comparisons revealed that both users' and nonusers' attitudes were significantly influenced by the affective component. Perceived outcomes of park use was not predictive of attitude for either group. The values component (on an anthropocentric-biocentric scale) was significant for users, but not nonusers. Nonusers attitudes were also significantly impacted by the behavioral component (i.e., behaviors related to parks), and by social networks. Social networks were not predictive of users' park attitudes. The research I have presented herein provides support for the hypotheses that time spent in natural settings is associated with better physical and psychological health and that community green spaces contribute to satisfaction with one's neighborhood. I also found that attitudes about parks differed between users and nonusers, yet both groups valued them as benefits in the urban environment. Since my sample size was insufficient to make generalizable statements about Portland's population, my results are suggestive, but are consistent with prior research. My research results can help urban natural resource managers and city decision-makers make more inclusive decisions by incorporating an understanding of city residents' relationships to urban nature parks. The results of my research on personal and community health support the position that urban green space fulfills an important function by providing valuable public health benefits, and promoting healthier, more "livable" communities. My results indicate that, for my sample, social interaction at parks was positively related to neighborhood health. Such a positive association suggests that parks could be leveraged to build community cohesion which ultimately leads to benefits like increased sense of safety and happier residents. My results pertaining to park attitudes can help managers develop more targeted public outreach campaigns. For instance, I found that for park nonusers, social networks were a statistically significant predictor of park attitudes. This result implies that park staff and managers could benefit by identifying community organizations and business associations that might be conduits to reach nonusers. Through such information pathways, park managers could disseminate information about urban nature parks that could attract current nonusers. Urban nature parks are not the sole answer to building healthier communities and people. They cannot alone reverse social ills that many urban neighborhoods contend with routinely. However, the scientific data do support the idea that urban natural spaces like nature parks are positively associated with personal and community health. With careful participatory planning that includes a substantial public input component, urban natural resource managers could develop urban nature parks as part of a city's green infrastructure that not only provides valuable ecosystem services like cleaner water and reduced energy consumption, but also provides for nature-based recreation experiences that promote healthier, happier city residents. Title: Urban natural parks in Portland : nature, networks, and community health Author: Baur, Joshua W. R. Three trends are occurring today in the United States which inspired this research. First, America is growing increasingly urbanized. Today, more Americans are living in cities than in rural environments, and this pattern is predicted to continue for the foreseeable future. Urban living has benefits, but there are also challenges for city residents including pollution, traffic, and crime. As social scientists, we need to improve our understanding of urban dwellers' relationship with their natural environment just as biophysical scientists are focusing more and more on the impacts of urban development on the natural world. Second, Americans are spending less time recreating outdoors. There has been a documented decline of participation in nature-based recreation, likely being replaced by an increase in use of electronic media during people's leisure time. Less contact with nature has consequences for people, perhaps especially for city dwellers who spend the majority of their time surrounded by the built environment of concrete and asphalt. It is likely that reliance on electronic entertainment has played a substantial role in decreasing amounts of physical activity. Lastly, Americans are becoming more sedentary. Today, the number of Americans who report getting no physical activity is about equal to the number who report getting regular physical exercise during their free time. Rising rates of obesity for adults and children in the U.S. have raised considerable concerns among medical and public policy professionals. The purpose of this research was to examine how small-scale urban nature parks are affecting city residents in Portland, OR. I looked at three elements of Portland residents' relationship with urban nature parks. First, I looked at whether there was an association between individual physical and psychological health and park use. Prior research has revealed that people who spend time recreating outdoors tend to be more physically active than people who do not. These observed higher levels of physical activity are associated with improved physical health. Time in nature settings has also demonstrated a positive effect on psychological well-being, such as reduced anxiety and improved ability to concentrate. Second, I examined whether having a nature park in their community had an effect on Portland residents' sense of neighborhood health. Previous research suggests that having natural areas in urbanized areas directly contributes to city residents' sense of a stronger, healthier community. Green space in cities has been associated with not only higher levels of reported satisfaction with the neighborhood, but also with higher property values, and with higher levels of retail spending. Third, I employed a social psychological model of attitude formation to evaluate Portland residents' attitudes about their nature parks. Attitudes are particularly important for natural resource managers to understand and account for in policy decisions since management of natural resources often engages the public's sense of personal freedoms and concerns over government regulations. Furthermore, because people in cities are so closely in contact with urban green space on a regular basis, inclusive and responsive policy requires that managers take account of public attitudes. I collected the data relating to these three elements of the relationship between urban residents and their nature parks in Portland because it is the largest city in Oregon. I obtained the data through a general population survey, randomly distributed to residents in the Portland metropolitan area during the fall of 2010. I conducted customary social science statistical analysis, including linear regression, to assess the relationship between Portland nature parks and personal and community health. To evaluate my sample's attitudes, I used the tripartite model of attitude formation originally developed in social psychology research. Because I was working with latent factors of attitude formation, I used structural equation modeling to assess the relationship of the observed variables to their latent factors, and the relationship among the latent factors. My results largely agree with those of other researchers, though I approached the question of physical health and nature recreation slightly differently. For my work on physical health, rather than ask about physical activity and infer health outcomes, I asked directly about physical health. I tested two hypotheses. One hypothesis was that there would be a positive association between self-reported physical health and park use, and the other tested for a positive association between park use and psychological health. My hypothesis for the physical health-parks relationship was partially supported. I tested two physical health variables, and found that one, which described overall health, did reveal a statistically significant relationship to park use. The other, relating to role limitations due to physical health problems, did not have a significant relationship to park use. My second hypothesis asserted that there would be a positive relationship between psychological health and park user status. This hypothesis was not supported, but I did find indications of an association between psychological health and park use. The second element of the relationship between city residents and urban nature parks related to neighborhood health. My results from this analysis were consistent with prior research findings which tend to support a positive association. I tested whether parks close by respondents homes (a fifteen to twenty minute walk), and parks farther away (no more than a ten minute drive away from home) were positively associated with self-reported neighborhood health. I found that both levels of proximity were positively associated with perceptions of neighborhood health. Because prior research suggests that one of the ways that neighborhood green spaces promote stronger communities is through the social interactions that occur in parks among neighbors, I also tested whether park-related social interaction was positively associated with community health ratings. In testing for a mediating effect of social interaction on the relationship between parks and neighborhood health, I found that park-related social interaction had a partial mediating effect on neighborhood health ratings for both parks within walking distance and within driving distance. In testing for moderation, I found that the moderation effect of social interaction was present only for parks within walking distance. The third and final element of the relationship between urban nature parks and city dwellers was attitudes about urban nature parks. I employed a model of attitude formation originally proposed in the social psychology literature. The tripartite model argues that an attitude is formed through three precursors: the cognitive, the affective, and the behavioral components. I also included an additional variable for social networks which I proposed would act as a moderating variable on the relationship between the other components and park attitude. My results for the entire, combined sample of both park users and nonusers indicated that both the cognitive factor and the affective factor have a significant association with attitude formation, while the behavioral component did not. The model for the combined sample also showed that social networks had a statistically significant, inverse relationship with attitudes. I conducted a test for attitude differences between groups (users and nonusers), and found a statistically significant difference. I also tested for a moderating effect of social networks on the other attitude formation components, but that relationship was not supported. Finally, I conducted comparisons between the two groups to assess any differences in the attitude components between users and nonusers. Side-by-side comparisons revealed that both users' and nonusers' attitudes were significantly influenced by the affective component. Perceived outcomes of park use was not predictive of attitude for either group. The values component (on an anthropocentric-biocentric scale) was significant for users, but not nonusers. Nonusers attitudes were also significantly impacted by the behavioral component (i.e., behaviors related to parks), and by social networks. Social networks were not predictive of users' park attitudes. The research I have presented herein provides support for the hypotheses that time spent in natural settings is associated with better physical and psychological health and that community green spaces contribute to satisfaction with one's neighborhood. I also found that attitudes about parks differed between users and nonusers, yet both groups valued them as benefits in the urban environment. Since my sample size was insufficient to make generalizable statements about Portland's population, my results are suggestive, but are consistent with prior research. My research results can help urban natural resource managers and city decision-makers make more inclusive decisions by incorporating an understanding of city residents' relationships to urban nature parks. The results of my research on personal and community health support the position that urban green space fulfills an important function by providing valuable public health benefits, and promoting healthier, more "livable" communities. My results indicate that, for my sample, social interaction at parks was positively related to neighborhood health. Such a positive association suggests that parks could be leveraged to build community cohesion which ultimately leads to benefits like increased sense of safety and happier residents. My results pertaining to park attitudes can help managers develop more targeted public outreach campaigns. For instance, I found that for park nonusers, social networks were a statistically significant predictor of park attitudes. This result implies that park staff and managers could benefit by identifying community organizations and business associations that might be conduits to reach nonusers. Through such information pathways, park managers could disseminate information about urban nature parks that could attract current nonusers. Urban nature parks are not the sole answer to building healthier communities and people. They cannot alone reverse social ills that many urban neighborhoods contend with routinely. However, the scientific data do support the idea that urban natural spaces like nature parks are positively associated with personal and community health. With careful participatory planning that includes a substantial public input component, urban natural resource managers could develop urban nature parks as part of a city's green infrastructure that not only provides valuable ecosystem services like cleaner water and reduced energy consumption, but also provides for nature-based recreation experiences that promote healthier, happier city residents. Close

• 1743. [Article] Effect of selenium source and supplementation rate in ewes on selenium status, passive immunity and growth performance of their lambs

  Selenium (Se) is an essential micronutrient of sheep. Supplementation is especially important in young lambs in order to prevent Se-deficiency signs. In the United States, the FDA regulates Se supplementation ...

  Citation × Citation Citation Abstract Copy Title: Effect of selenium source and supplementation rate in ewes on selenium status, passive immunity and growth performance of their lambs Author: Stewart, Whitney C. Selenium (Se) is an essential micronutrient of sheep. Supplementation is especially important in young lambs in order to prevent Se-deficiency signs. In the United States, the FDA regulates Se supplementation to ruminant diets at a level of 0.3 mg/kg Se (as fed basis). Questions still exist regarding what chemical form of Se is the most bioavailable supplement and what are the best supplementation rates for optimal productivity. Three interrelated experiments from the same study were conducted 1) to evaluate the effect of Se source and supplementation rate in ewes on Se status of their lambs at birth, 2) to examine the effect of Se source and supplementation rate on IgG concentrations in ewe colostrum and lamb serum, and 3) to evaluate the effects of Se source and supplementation rate on ewe reproductive performance and subsequent vitality and growth performance of their lambs. For these experiments, 240 ewes were divided into 8 treatment groups and drenched weekly (at an amount equal to their summed daily intake) for one year, including during gestation and early lactation, with no Se (deficient); at recommended levels (0.3 mg/kg) with inorganic sodium selenite, sodium selenate, or organic Se-yeast (Se-Y); or at supranutritional levels (0.9 and 1.5 mg/kg) with sodium selenite or Se yeast. In the third experiment, 88 ewes continued the study into year two for an additional 28 weeks. Year two treatments included no Se (deficient) ewes (n = 25); ewes supplemented at recommended levels (0.3 mg/kg) with organic Se-Y (n = 20); ewes supplemented at supranutritional levels (0.9 and 1.5 mg/kg) with organic Se-Y (n = 18 and 27, respectively). In the first experiment, which assessed the effects of Se source and supplementation rate in ewes on Se status of their offspring, we found that Se administered by weekly drenching of ewes during gestation and early lactation was effective at increasing Se concentrations in ewe colostrum and milk at 30 days in milk (DIM), and in improving the Se status of lambs (whole-blood and serum Se at birth, and skeletal-muscle Se at 14 days of age) (all P < 0.001). Selenium concentrations in lacteal secretions and lambs were higher in ewes drenched with Se yeast compared to ewes drenched with inorganic Se sources (P < 0.01). Selenium concentrations in lacteal secretions and in lambs increased linearly with supranutritional concentrations of Se yeast (P < 0.001), whereas Se concentrations did not differ in ewes drenched with 0.9 or 1.5 mg/kg of inorganic sodium selenite (P > 0.05). In summary, weekly oral drenching of ewes with Se yeast during gestation and early lactation was found to be an effective method for improving Se status of their newborn lambs. In the second experiment, which examined the effects of Se source and supplementation rate in ewes on colostral IgG and lamb serum-IgG concentrations, we measured colostral and lamb serum-IgG concentrations at parturition, and lamb serum-IgG concentration again at 48 hours postnatal. Although Se drenching of ewes was effective at increasing whole-blood Se concentrations in ewes and lambs (P < 0.001), and colostral Se concentration (P < 0.001), there was no consistent or significant increase in IgG concentrations in ewe colostrum nor lamb serum at 48 hours of age (P > 0.05) irrespective of Se source, or supplementation rate. Therefore, we conclude that Se supplementation in ewes, and the Se status of newborn lambs, have little effect on IgG concentrations in colostrum and subsequent IgG concentrations in lamb serum at 48 hours postnatal. The purpose of the third experiment was to examine the effect of Se source and supplementation rate on ewe reproductive performance and subsequent vitality and growth performance of lambs, over two consecutive lambing seasons. In year one, lambing percent; number of lambs born per ewe; lamb birth weights; 90- and 120-day BW and ADG; and pounds of lamb weaned per ewe were measured. The purpose of the second year of this study was to continue our observations for the SeY treated ewes, adding additional parameters to monitor ewe reproductive performance (percentage of ewes exhibiting estrus; percentage of ewes exhibiting estrus that lambed; percentage of ewes lambing; and number of lambs born per ewe). Year two lamb performance measures included birth weights; neonatal vigor scores; 10-, 20-, and 60-day BW and ADG; and percentage of lambs surviving to 60 days. In year one, Se supplementation, regardless of supplementation rate, did not affect lambing percent, number of lambs born per ewe, lamb birth weights, 90-day BW and ADG, or pounds of lamb weaned per ewe. However, lambs from ewes in the 1.5 mg/kg SeY group had greater120-day BW (P = 0.10) and ADG (P = 0.06) than lambs from ewes in the 0.3 mg/kg group. This same trend was apparent in a subgroup of lambs from Suffolk ewes receiving Se at 1.5 mg/kg that had greater 120-day BW (P = 0.07) and ADG (P = 0.09) compared to lambs receiving SeY at 0.3 mg/kg. Similarly, a subgroup of lambs reared as twins from ewes receiving Se at 1.5 mg/kg had greater120-day BW (P = 0.07) and ADG (P = 0.08) than lambs reared as twins from ewes in the 0.3 mg/kg group. In year two, there were two ewe reproductive performance measures that were negatively affected by Se supplementation. First, the percentage of ewes exhibiting estrus that lambed in the 0.3 mg/kg SeY group (75%) was lower compared to ewes receiving no Se supplement (100%; P = 0.02). Also, the percentage of ewes lambing was lower (P< 0.04) for ewes receiving 0.3 mg/kg SeY (75%) compared to ewes receiving no Se supplemental (96%). Se supplementation, regardless of source and supplementation rate did not affect percentage of ewes exhibiting estrus, or number of lambs born per ewe. There were three lamb performance measures that were affected by Se supplementation. Lambs from ewes receiving Se at 1.5 mg/kg tended to have greater lamb vigor scores compared to lambs from ewes receiving SeY at 0.3 mg/kg (P = 0.07). Second, the 60-day ADG was greater for lambs from ewes in the 1.5 mg/kg group compared to lambs from ewes in the no Se group (P =0.07). A subgroup of lambs from Suffolk ewes receiving Se at 1.5 mg/kg had greater 60-day BW (P = 0.03) and ADG (P = 0.06) compared to lambs receiving SeY at 0.3 mg/kg. Similarly, a subgroup of lambs reared as twins from ewes receiving Se at 1.5 mg/kg had greater 60-day BW (P = 0.08) and ADG (P = 0.06) than lambs reared as twins from ewes in the 0.3 mg/kg group. Third, there was an increased percentage of lambs surviving to 60 days in lambs from ewes in the 1.5 mg/kg group compared to lambs from ewes in the no Se group (86% vs. 64%, respectively; P =0.04). Se supplementation, regardless of source and supplementation rate, did not affect lamb birth weight nor 10- and 20-day BW and ADG. We conclude that supranutritional Se supplementation of ewes, primarily with SeY, positively affects later lamb performance measures (i.e., 60- and 120-day BW and ADG), and that these effects may be more pronounced for lambs of heavier breed (i.e., Suffolk) and lambs reared as twins. Title: Effect of selenium source and supplementation rate in ewes on selenium status, passive immunity and growth performance of their lambs Author: Stewart, Whitney C. Selenium (Se) is an essential micronutrient of sheep. Supplementation is especially important in young lambs in order to prevent Se-deficiency signs. In the United States, the FDA regulates Se supplementation to ruminant diets at a level of 0.3 mg/kg Se (as fed basis). Questions still exist regarding what chemical form of Se is the most bioavailable supplement and what are the best supplementation rates for optimal productivity. Three interrelated experiments from the same study were conducted 1) to evaluate the effect of Se source and supplementation rate in ewes on Se status of their lambs at birth, 2) to examine the effect of Se source and supplementation rate on IgG concentrations in ewe colostrum and lamb serum, and 3) to evaluate the effects of Se source and supplementation rate on ewe reproductive performance and subsequent vitality and growth performance of their lambs. For these experiments, 240 ewes were divided into 8 treatment groups and drenched weekly (at an amount equal to their summed daily intake) for one year, including during gestation and early lactation, with no Se (deficient); at recommended levels (0.3 mg/kg) with inorganic sodium selenite, sodium selenate, or organic Se-yeast (Se-Y); or at supranutritional levels (0.9 and 1.5 mg/kg) with sodium selenite or Se yeast. In the third experiment, 88 ewes continued the study into year two for an additional 28 weeks. Year two treatments included no Se (deficient) ewes (n = 25); ewes supplemented at recommended levels (0.3 mg/kg) with organic Se-Y (n = 20); ewes supplemented at supranutritional levels (0.9 and 1.5 mg/kg) with organic Se-Y (n = 18 and 27, respectively). In the first experiment, which assessed the effects of Se source and supplementation rate in ewes on Se status of their offspring, we found that Se administered by weekly drenching of ewes during gestation and early lactation was effective at increasing Se concentrations in ewe colostrum and milk at 30 days in milk (DIM), and in improving the Se status of lambs (whole-blood and serum Se at birth, and skeletal-muscle Se at 14 days of age) (all P < 0.001). Selenium concentrations in lacteal secretions and lambs were higher in ewes drenched with Se yeast compared to ewes drenched with inorganic Se sources (P < 0.01). Selenium concentrations in lacteal secretions and in lambs increased linearly with supranutritional concentrations of Se yeast (P < 0.001), whereas Se concentrations did not differ in ewes drenched with 0.9 or 1.5 mg/kg of inorganic sodium selenite (P > 0.05). In summary, weekly oral drenching of ewes with Se yeast during gestation and early lactation was found to be an effective method for improving Se status of their newborn lambs. In the second experiment, which examined the effects of Se source and supplementation rate in ewes on colostral IgG and lamb serum-IgG concentrations, we measured colostral and lamb serum-IgG concentrations at parturition, and lamb serum-IgG concentration again at 48 hours postnatal. Although Se drenching of ewes was effective at increasing whole-blood Se concentrations in ewes and lambs (P < 0.001), and colostral Se concentration (P < 0.001), there was no consistent or significant increase in IgG concentrations in ewe colostrum nor lamb serum at 48 hours of age (P > 0.05) irrespective of Se source, or supplementation rate. Therefore, we conclude that Se supplementation in ewes, and the Se status of newborn lambs, have little effect on IgG concentrations in colostrum and subsequent IgG concentrations in lamb serum at 48 hours postnatal. The purpose of the third experiment was to examine the effect of Se source and supplementation rate on ewe reproductive performance and subsequent vitality and growth performance of lambs, over two consecutive lambing seasons. In year one, lambing percent; number of lambs born per ewe; lamb birth weights; 90- and 120-day BW and ADG; and pounds of lamb weaned per ewe were measured. The purpose of the second year of this study was to continue our observations for the SeY treated ewes, adding additional parameters to monitor ewe reproductive performance (percentage of ewes exhibiting estrus; percentage of ewes exhibiting estrus that lambed; percentage of ewes lambing; and number of lambs born per ewe). Year two lamb performance measures included birth weights; neonatal vigor scores; 10-, 20-, and 60-day BW and ADG; and percentage of lambs surviving to 60 days. In year one, Se supplementation, regardless of supplementation rate, did not affect lambing percent, number of lambs born per ewe, lamb birth weights, 90-day BW and ADG, or pounds of lamb weaned per ewe. However, lambs from ewes in the 1.5 mg/kg SeY group had greater120-day BW (P = 0.10) and ADG (P = 0.06) than lambs from ewes in the 0.3 mg/kg group. This same trend was apparent in a subgroup of lambs from Suffolk ewes receiving Se at 1.5 mg/kg that had greater 120-day BW (P = 0.07) and ADG (P = 0.09) compared to lambs receiving SeY at 0.3 mg/kg. Similarly, a subgroup of lambs reared as twins from ewes receiving Se at 1.5 mg/kg had greater120-day BW (P = 0.07) and ADG (P = 0.08) than lambs reared as twins from ewes in the 0.3 mg/kg group. In year two, there were two ewe reproductive performance measures that were negatively affected by Se supplementation. First, the percentage of ewes exhibiting estrus that lambed in the 0.3 mg/kg SeY group (75%) was lower compared to ewes receiving no Se supplement (100%; P = 0.02). Also, the percentage of ewes lambing was lower (P< 0.04) for ewes receiving 0.3 mg/kg SeY (75%) compared to ewes receiving no Se supplemental (96%). Se supplementation, regardless of source and supplementation rate did not affect percentage of ewes exhibiting estrus, or number of lambs born per ewe. There were three lamb performance measures that were affected by Se supplementation. Lambs from ewes receiving Se at 1.5 mg/kg tended to have greater lamb vigor scores compared to lambs from ewes receiving SeY at 0.3 mg/kg (P = 0.07). Second, the 60-day ADG was greater for lambs from ewes in the 1.5 mg/kg group compared to lambs from ewes in the no Se group (P =0.07). A subgroup of lambs from Suffolk ewes receiving Se at 1.5 mg/kg had greater 60-day BW (P = 0.03) and ADG (P = 0.06) compared to lambs receiving SeY at 0.3 mg/kg. Similarly, a subgroup of lambs reared as twins from ewes receiving Se at 1.5 mg/kg had greater 60-day BW (P = 0.08) and ADG (P = 0.06) than lambs reared as twins from ewes in the 0.3 mg/kg group. Third, there was an increased percentage of lambs surviving to 60 days in lambs from ewes in the 1.5 mg/kg group compared to lambs from ewes in the no Se group (86% vs. 64%, respectively; P =0.04). Se supplementation, regardless of source and supplementation rate, did not affect lamb birth weight nor 10- and 20-day BW and ADG. We conclude that supranutritional Se supplementation of ewes, primarily with SeY, positively affects later lamb performance measures (i.e., 60- and 120-day BW and ADG), and that these effects may be more pronounced for lambs of heavier breed (i.e., Suffolk) and lambs reared as twins. Close

• 1744. [Article] Crustal architecture and magma dynamics in a large continental magmatic system : a case study of the Purico-Chascon Volcanic Complex, Northern Chile

  The ~1 Myr history of the Purico-Chascon volcanic complex (PCVC) records significant changes in the production and storage of magmas in the crust. At ~1 Ma activity at the PCVC initiated with the eruption ...

  Citation × Citation Citation Abstract Copy Title: Crustal architecture and magma dynamics in a large continental magmatic system : a case study of the Purico-Chascon Volcanic Complex, Northern Chile Author: Burns, Dale H. The ~1 Myr history of the Purico-Chascon volcanic complex (PCVC) records significant changes in the production and storage of magmas in the crust. At ~1 Ma activity at the PCVC initiated with the eruption of a large 80-100 km³ crystal-rich dacite ignimbrite with restricted whole rock ⁸⁷Sr/⁸⁶Sr isotope ratios between 0.7085-0.7090. In-situ analyses of plagioclase from the Purico ignimbrite have ⁸⁷Sr/⁸⁶Sr=0.7087-0.7090. The dacite magma accumulated and evolved at relatively low temperatures around 800-850 °C in the upper crust at 4-8 km depth. Minor andesite and rhyolite pumice late in the sequence have similar restricted whole rock ⁸⁷Sr/⁸⁶Sr=0.7089-0.7091. The radiogenic isotopes of this 0.98 Ma activity are consistent with all these compositions resulting from 50 to 70% crustal assimilation by parental Central Andean "baseline" magmas at depths between 15-30 km. The final eruptions at the PCVC occurred <0.18 Ma producing three small < 5 km³ crystal-rich dacite lava domes with whole rock ⁸⁷Sr/⁸⁶Sr ratios 0.7075 to 0.7081 containing abundant basaltic-andesite enclaves with whole rock ⁸⁷Sr/⁸⁶Sr ratios of 0.7057- 0.7061. Plagioclase and amphibole from samples from the largest of these domes, Cerro Chascon, record two distinct magmatic environments; an upper crustal environment identical to the Purico ignimbrite and a second deeper, ~15-20 km depth, higher temperature (~922-1001 °C) environment consistent with conditions recorded in the basaltic andesite enclaves. Accordingly, plagioclase cores in the host dacite lava and enclaves have enriched in-situ ⁸⁷Sr/⁸⁶Sr isotopic compositions of 0.7083 to 0.7095 while plagioclase rims and microphenocrysts in the enclaves have ⁸⁷Sr/⁸⁶Sr isotope ratios from 0.7057 to 0.7065 and 0.7062 to 0.7064 respectively. Lavas from Cerro Chascon also contain abundant Fo82 olivine with spinel and basaltic melt inclusions that crystallized in a deep crustal environment (>1250 °C) consistent with a lower crustal MASH zone. The high baseline isotopic ratios observed in bulk rock and plagioclase crystals from Cerro Chascon (0.7057-0.7065) are consistent with MASH processes. The evolution of the PCVC is a microcosm of the Andean arc in this region where, from 10 - 1 Ma, dominantly dacitic upper crustal magmatism of the Altiplano-Puna Volcanic Complex ignimbrite flare-up persisted until ~1 Ma, when smaller volume, more heterogeneous and less isotopically enriched basaltic andesite to dacite composite volcanoes signal a return to steady state arc volcanism. I suggest that the PCVC captures the transition of the Andean arc from flare-up to steady state. The temporal trend at the PCVC is consistent with a waning thermal flux. High magmatic fluxes during the flare-up would have resulted in elevated geothermal gradients and efficient crustal processing leading to a dominantly dacitic upper crust (0 to 35 km) that fed the large volume Purico ignimbrite. As magmatic flux and thermal energy wanes, crustal isotherms relax resulting in greater thermal contrast between parental magmas, crust and remnant upper crustal dacite magma. This manifests in more heterogeneity and the survival of less isotopically enriched magmas in the upper crust. These arc scale magma dynamics are recorded even at the intra-crystalline scale. Individual crystals from Cerro Chascon also record vital information on the crystallization and evolution of mantle-derived magmas in continental magmatic arcs. Fo₈₂ olivine, olivine hosted spinel, and basaltic melt inclusions record the crystallization of olivine at >1250 °C in conditions consistent with a lower crustal (~70 km depth) MASH zone. Another significant crystallization event appears to have occurred at ~20 km depth, characterized by the crystallization of high An plagioclase (An₇₂₋₈₄) at ~1100-1050 °C followed by high-Al amphibole (~12-15 wt.% Al₂O₃) at ~1000-950 °C. The appearance of amphibole on the liquidus appears to have resulted from a nearly 2-fold increase in melt water content following ~45% crystallization of high An plagioclase. Following this extensive crystallization the highly crystalline mafic magma ascended into the upper crust and interacted with the remnant crystal mush from the Purico ignimbrite magma reservoir. Low An plagioclase (An₃₉₋₅₅), low Al amphibole (~6-9 wt.% Al₂O₃), sanidine, and biotite retain the chemical composition of the Purico ignimbrite magma, whereas, olivine, high An plagioclase, and high Al amphibole record the mafic recharge magma. The textures and compositions observed in Cerro Chascon are common in both continental and oceanic magmatic arcs worldwide and I propose that multiple crystallization events and upper crustal assimilation are fundamental processes intrinsic to arc magmatism. I have also used in situ ⁸⁷Sr/⁸⁶Sr isotope ratios in plagioclase from andesite, dacite, and rhyolite pumice from the ~1 Ma Purico ignimbrite to determine the cause for compositional zoning in the Purico ignimbrite magma reservoir. Andesite pumice contains two texturally, compositionally, and isotopically distinct types of plagioclase, small (<500 μm) subhedral to euhedral crystals with high MgO (130-490 ppm) and low ⁸⁷Sr/⁸⁶r crystals (0.7076-0.7084) record a hot (>900 °C) andesite magma derived from an ~20 km deep magma reservoir. In contrast, the second type of plagioclase in the andesite appear to broken fragments of larger crystals and have significantly lower MgO (90-240 ppm), higher ⁸⁷Sr/⁸⁶Sr (0.7096-0.7114), and appears to be derived from the lower temperature (crystallized at ~800-900 °C), upper crustal (<10 km) plutonic basement. Dacite pumice also contains two texturally and compositionally distinct types of plagioclase. However, both types have very restricted MgO (b.d.l.-200 ppm) and ⁸⁷Sr/⁸⁶Sr (0.7085-0.7095) ratios and appear to have grown at ~850°C. These crystals are also significantly larger (>1000 μm) than plagioclase from the andesite pumice and have clear euhedral rims. Rhyolite pumice from the Purico ignimbrite also contains distinct types of plagioclase. Both types of plagioclase are similar in size (<500 μm) and appear to be fragments of larger crystals. One type is characterized by low MgO (b.d.l.-240 ppm) and restricted ⁸⁷Sr/⁸⁶Sr isotope ratios (0.7088-0.7095) similar to plagioclase in the dacite pumice, and the other has significantly higher ⁸⁷Sr/⁸⁶Sr ratios (0.7095-0.7103) consistent with the upper crustal ignimbrite basement. The compositional variations observed in plagioclase crystals from the Purico ignimbrites are consistent with the recharge of a previously emplaced upper crustal (4-8 km depth) dacite magma reservoir by a hotter, deeper (20 km deep) andesite. During ascent, the andesite incorporated crystals from the surrounding upper crustal plutonic bodies before pooling against the residence dacite magma and crystallizing. Crystallization of the andesite resulted in the expulsion of a rhyolite interstitial melt that ascended through the dacite reservoir and pooled at the top of the reservoir. The rhyolite melt incorporated crystals from the dacite magma during ascent as well as crystals from the roof rock, which in the case of the Purico ignimbrite represents the plutonic remnants from other large silicic magmatic systems associated with the APVC. Thus, the compositional variations observed in the Purico ignimbrite results from a combination of crustal assimilation, crystallization, and melt extraction all initiated by mafic recharge. Title: Crustal architecture and magma dynamics in a large continental magmatic system : a case study of the Purico-Chascon Volcanic Complex, Northern Chile Author: Burns, Dale H. The ~1 Myr history of the Purico-Chascon volcanic complex (PCVC) records significant changes in the production and storage of magmas in the crust. At ~1 Ma activity at the PCVC initiated with the eruption of a large 80-100 km³ crystal-rich dacite ignimbrite with restricted whole rock ⁸⁷Sr/⁸⁶Sr isotope ratios between 0.7085-0.7090. In-situ analyses of plagioclase from the Purico ignimbrite have ⁸⁷Sr/⁸⁶Sr=0.7087-0.7090. The dacite magma accumulated and evolved at relatively low temperatures around 800-850 °C in the upper crust at 4-8 km depth. Minor andesite and rhyolite pumice late in the sequence have similar restricted whole rock ⁸⁷Sr/⁸⁶Sr=0.7089-0.7091. The radiogenic isotopes of this 0.98 Ma activity are consistent with all these compositions resulting from 50 to 70% crustal assimilation by parental Central Andean "baseline" magmas at depths between 15-30 km. The final eruptions at the PCVC occurred <0.18 Ma producing three small < 5 km³ crystal-rich dacite lava domes with whole rock ⁸⁷Sr/⁸⁶Sr ratios 0.7075 to 0.7081 containing abundant basaltic-andesite enclaves with whole rock ⁸⁷Sr/⁸⁶Sr ratios of 0.7057- 0.7061. Plagioclase and amphibole from samples from the largest of these domes, Cerro Chascon, record two distinct magmatic environments; an upper crustal environment identical to the Purico ignimbrite and a second deeper, ~15-20 km depth, higher temperature (~922-1001 °C) environment consistent with conditions recorded in the basaltic andesite enclaves. Accordingly, plagioclase cores in the host dacite lava and enclaves have enriched in-situ ⁸⁷Sr/⁸⁶Sr isotopic compositions of 0.7083 to 0.7095 while plagioclase rims and microphenocrysts in the enclaves have ⁸⁷Sr/⁸⁶Sr isotope ratios from 0.7057 to 0.7065 and 0.7062 to 0.7064 respectively. Lavas from Cerro Chascon also contain abundant Fo82 olivine with spinel and basaltic melt inclusions that crystallized in a deep crustal environment (>1250 °C) consistent with a lower crustal MASH zone. The high baseline isotopic ratios observed in bulk rock and plagioclase crystals from Cerro Chascon (0.7057-0.7065) are consistent with MASH processes. The evolution of the PCVC is a microcosm of the Andean arc in this region where, from 10 - 1 Ma, dominantly dacitic upper crustal magmatism of the Altiplano-Puna Volcanic Complex ignimbrite flare-up persisted until ~1 Ma, when smaller volume, more heterogeneous and less isotopically enriched basaltic andesite to dacite composite volcanoes signal a return to steady state arc volcanism. I suggest that the PCVC captures the transition of the Andean arc from flare-up to steady state. The temporal trend at the PCVC is consistent with a waning thermal flux. High magmatic fluxes during the flare-up would have resulted in elevated geothermal gradients and efficient crustal processing leading to a dominantly dacitic upper crust (0 to 35 km) that fed the large volume Purico ignimbrite. As magmatic flux and thermal energy wanes, crustal isotherms relax resulting in greater thermal contrast between parental magmas, crust and remnant upper crustal dacite magma. This manifests in more heterogeneity and the survival of less isotopically enriched magmas in the upper crust. These arc scale magma dynamics are recorded even at the intra-crystalline scale. Individual crystals from Cerro Chascon also record vital information on the crystallization and evolution of mantle-derived magmas in continental magmatic arcs. Fo₈₂ olivine, olivine hosted spinel, and basaltic melt inclusions record the crystallization of olivine at >1250 °C in conditions consistent with a lower crustal (~70 km depth) MASH zone. Another significant crystallization event appears to have occurred at ~20 km depth, characterized by the crystallization of high An plagioclase (An₇₂₋₈₄) at ~1100-1050 °C followed by high-Al amphibole (~12-15 wt.% Al₂O₃) at ~1000-950 °C. The appearance of amphibole on the liquidus appears to have resulted from a nearly 2-fold increase in melt water content following ~45% crystallization of high An plagioclase. Following this extensive crystallization the highly crystalline mafic magma ascended into the upper crust and interacted with the remnant crystal mush from the Purico ignimbrite magma reservoir. Low An plagioclase (An₃₉₋₅₅), low Al amphibole (~6-9 wt.% Al₂O₃), sanidine, and biotite retain the chemical composition of the Purico ignimbrite magma, whereas, olivine, high An plagioclase, and high Al amphibole record the mafic recharge magma. The textures and compositions observed in Cerro Chascon are common in both continental and oceanic magmatic arcs worldwide and I propose that multiple crystallization events and upper crustal assimilation are fundamental processes intrinsic to arc magmatism. I have also used in situ ⁸⁷Sr/⁸⁶Sr isotope ratios in plagioclase from andesite, dacite, and rhyolite pumice from the ~1 Ma Purico ignimbrite to determine the cause for compositional zoning in the Purico ignimbrite magma reservoir. Andesite pumice contains two texturally, compositionally, and isotopically distinct types of plagioclase, small (<500 μm) subhedral to euhedral crystals with high MgO (130-490 ppm) and low ⁸⁷Sr/⁸⁶r crystals (0.7076-0.7084) record a hot (>900 °C) andesite magma derived from an ~20 km deep magma reservoir. In contrast, the second type of plagioclase in the andesite appear to broken fragments of larger crystals and have significantly lower MgO (90-240 ppm), higher ⁸⁷Sr/⁸⁶Sr (0.7096-0.7114), and appears to be derived from the lower temperature (crystallized at ~800-900 °C), upper crustal (<10 km) plutonic basement. Dacite pumice also contains two texturally and compositionally distinct types of plagioclase. However, both types have very restricted MgO (b.d.l.-200 ppm) and ⁸⁷Sr/⁸⁶Sr (0.7085-0.7095) ratios and appear to have grown at ~850°C. These crystals are also significantly larger (>1000 μm) than plagioclase from the andesite pumice and have clear euhedral rims. Rhyolite pumice from the Purico ignimbrite also contains distinct types of plagioclase. Both types of plagioclase are similar in size (<500 μm) and appear to be fragments of larger crystals. One type is characterized by low MgO (b.d.l.-240 ppm) and restricted ⁸⁷Sr/⁸⁶Sr isotope ratios (0.7088-0.7095) similar to plagioclase in the dacite pumice, and the other has significantly higher ⁸⁷Sr/⁸⁶Sr ratios (0.7095-0.7103) consistent with the upper crustal ignimbrite basement. The compositional variations observed in plagioclase crystals from the Purico ignimbrites are consistent with the recharge of a previously emplaced upper crustal (4-8 km depth) dacite magma reservoir by a hotter, deeper (20 km deep) andesite. During ascent, the andesite incorporated crystals from the surrounding upper crustal plutonic bodies before pooling against the residence dacite magma and crystallizing. Crystallization of the andesite resulted in the expulsion of a rhyolite interstitial melt that ascended through the dacite reservoir and pooled at the top of the reservoir. The rhyolite melt incorporated crystals from the dacite magma during ascent as well as crystals from the roof rock, which in the case of the Purico ignimbrite represents the plutonic remnants from other large silicic magmatic systems associated with the APVC. Thus, the compositional variations observed in the Purico ignimbrite results from a combination of crustal assimilation, crystallization, and melt extraction all initiated by mafic recharge. Close

• 1745. [Article] How Do Population Growth, Land-use Regulations, and Precipitation Patterns Affect Water Use? A Fine-scale Empirical Analysis of Landscape Change

  A growing body of literature exists on how human population growth and changes in climatic factors influence the availability of water (Elliot et al. 2014, Prudhomme et al. 2014). These studies typically ...

  Citation × Citation Citation Abstract Copy Title: How Do Population Growth, Land-use Regulations, and Precipitation Patterns Affect Water Use? A Fine-scale Empirical Analysis of Landscape Change Author: Bigelow, Daniel P. A growing body of literature exists on how human population growth and changes in climatic factors influence the availability of water (Elliot et al. 2014, Prudhomme et al. 2014). These studies typically conclude that climate change is expected to have negative consequences on water availability, an effect that is magnified or exceeded by continued growth in human populations (Vorosmarty et al. 2000, Mcdonald et al. 2010). However, there are several deficiencies associated with how these existing studies from the natural science literature analyze the interconnectedness of the human-water-climate system. For one, the scale of the models that are employed often precludes researchers from accounting for the location-specific nature of how water is used. Failing to recognize the inherently spatial nature of water use compounds the inability of researchers to analyze the role of other spatially-dependent behavioral processes that are associated with population growth, and hence water use. The same can be said for the treatment of climate change in the existing literature. If the effects of climate change on water use are transmitted through intermediate human behavioral processes, ignoring the indirect nature of the relationship will not accurately convey the true localized outcomes that may be realized. Moreover, there may be policies in place that govern how certain spatial processes operate, which again cannot be accounted for without recognition of the fine-scale spatial aspects of water use. In this dissertation, I analyze the effects of population growth, land-use regulations, and climate change on localized consumptive water use through the lens of land-use change, an inherently spatial process. Intuitively, as a city's population expands and more land is developed at its extensive margin, the total amount of water consumed by the residential sector will correspondingly increase. However, I show that the net effect of land development on the total amount of water used by the agricultural and residential sectors combined depends primarily on three factors: (1) the amount and location of rainfed versus irrigated agricultural land within the vicinity of the city, (2) the rate of population growth occurring within the city, and (3) the spatial pattern associated with where new land development occurs. Somewhat counterintuitively, what I find is that under certain conditions more sprawl-like development patterns are associated with lower total water use. This result stems from the fact that low-density development patterns tend to be associated with increased conversion of irrigated agricultural land. Given the fact that irrigated agricultural land requires relatively more intensive water use when compared with urban land, lower density urbanization patterns can result in a reduction in total water use if the city expands into lands that are predominantly used for irrigated agriculture. My empirical approach combines fine-scale econometric and simulation methods in order to accommodate the spatial heterogeneity associated with land and water use in my study area, Oregon's Willamette Valley. In Chapter 3, I estimate a series of parcellevel hedonic property value models for land in developed, agricultural, and forest uses using a novel panel data set on land values for our study area, Oregon's Willamette Valley. Although the hedonic models are not an end in themselves, several policy applications are examined vis-a-vis the estimated property value relationships for each land use. First, for developed lands, I explore the effects of Oregon's comprehensive land-use plan, with specific focus on urban growth boundary designation, through the use of a variety of panel data estimators. Second, I analyze the relationship between agricultural land values and climatic influences, with particular emphasis on the interactions between the holding of irrigation rights and the effect of growing-season precipitation. The third application of the hedonic models pertains to how forest land values are influenced by transportation costs, represented by distance to the nearest processing mill, which change over time due to the large number of mill closures during my study period, partly in response to the old-growth harvest restrictions imposed by the Northwest Forest Plan. In Chapter 4, the estimated hedonic relationships are used to predict the values associated with land in selected and unselected uses in my land-use change data set, which comes from the US Geological Survey's Land Cover Trends (LCT) project. In a similar fashion to Bockstael (1996), I then use the land value predictions as explanatory variables in a set of discrete-choice urbanization models. In generating the predicted land values with the estimated hedonic relationships, I confront the sample selection issue inherent in applying the developed land hedonic model to lands that start in undeveloped uses using econometric methods suitable for panel data. I also compare the results generated with the coupled hedonic-urbanization approach with those from a reducedform model, which is more commonly found throughout the modern land economics literature. Additionally, using a Monte Carlo analysis, I illustrate the efficiency of the two-stage approach, and demonstrate how this property depends of the frequency of observed land development decisions. With my fully estimated econometric framework, I construct a spatially-explicit landscape simulation model in Chapter 5, which is used to analyze total water use over the period 2000-2070. The landscape simulations feature exogenous growth in population and income as the predominant drivers of urban land value dynamics. Agricultural water use is determined by spatial data on the location of irrigation water rights administered through the prior appropriation doctrine. Citywide urban demands are determined by the size of the city, demographic characteristics, water prices, pricing structure, and the demand for outdoor water use, which is influenced by precipitation. To generate my main results, I analyze three sets of scenarios in which I alter: (1) the area upon which land development is possible and (2) the city-specific population growth trajectory, and (3) the opportunity cost of land development for agricultural landowners. The first scenario set relates to the stringency of land-use regulations, which directly affects both the density of population growth and the urban composition of the city. Population growth, which is featured in the second set of scenarios, has several competing influences on total water use, among which are a direct influence on citywide residential water demand, and also the indirect effects that come about through the incentives to develop individual land parcels. In my third set of scenarios, I hold the land-use regulatory environment constant and impose permanent changes in precipitation patterns. Growing season precipitation indirectly influences total water use through its direct effect on the opportunity cost of land development for the owners of rainfed agricultural land. A novel feature of the simulation framework is that population density, which enters the developed land hedonic function, is treated as endogenous, as it is a function of development patterns and the permitted levels of development under different urban containment policies. Additionally, the simulation design is stochastic in that I treat land development decisions in a probabilistic fashion, facilitating an analysis of the distribution of results, including my main results for total water use, in each of the simulated scenarios. My results indicate that under situations that stimulate increased land development, the distribution of total water use is characterized by a lower mean if there is a sufficient amount of irrigated agricultural land in the vicinity of the city boundary, and if population growth is not prohibitively high. Further, the variance of total water use is decreasing in population density, as more sprawl-like development outcomes have a relatively wider array of potential spatial patterns associated with new land development. In the broadest sense, my dissertation highlights the interplay between population growth, climate change, land-use regulations, and the spatial patterns associated with both non-urban water endowments and new land development. The intermediate link that land-use change provides between climate change and population growth and water use has yet to be acknowledged and given proper treatment in the existing literature. Moreover, the connection between land-use change and water use emphasizes the inherent spatial heterogeneity in how water is used. Given the ubiquity of policies worldwide that impose location-specific constraints on water use, my analysis suggests that spatial considerations should be taken into account in subsequent studies that aim to analyze localized patterns of water use and how they may evolve in the future. Title: How Do Population Growth, Land-use Regulations, and Precipitation Patterns Affect Water Use? A Fine-scale Empirical Analysis of Landscape Change Author: Bigelow, Daniel P. A growing body of literature exists on how human population growth and changes in climatic factors influence the availability of water (Elliot et al. 2014, Prudhomme et al. 2014). These studies typically conclude that climate change is expected to have negative consequences on water availability, an effect that is magnified or exceeded by continued growth in human populations (Vorosmarty et al. 2000, Mcdonald et al. 2010). However, there are several deficiencies associated with how these existing studies from the natural science literature analyze the interconnectedness of the human-water-climate system. For one, the scale of the models that are employed often precludes researchers from accounting for the location-specific nature of how water is used. Failing to recognize the inherently spatial nature of water use compounds the inability of researchers to analyze the role of other spatially-dependent behavioral processes that are associated with population growth, and hence water use. The same can be said for the treatment of climate change in the existing literature. If the effects of climate change on water use are transmitted through intermediate human behavioral processes, ignoring the indirect nature of the relationship will not accurately convey the true localized outcomes that may be realized. Moreover, there may be policies in place that govern how certain spatial processes operate, which again cannot be accounted for without recognition of the fine-scale spatial aspects of water use. In this dissertation, I analyze the effects of population growth, land-use regulations, and climate change on localized consumptive water use through the lens of land-use change, an inherently spatial process. Intuitively, as a city's population expands and more land is developed at its extensive margin, the total amount of water consumed by the residential sector will correspondingly increase. However, I show that the net effect of land development on the total amount of water used by the agricultural and residential sectors combined depends primarily on three factors: (1) the amount and location of rainfed versus irrigated agricultural land within the vicinity of the city, (2) the rate of population growth occurring within the city, and (3) the spatial pattern associated with where new land development occurs. Somewhat counterintuitively, what I find is that under certain conditions more sprawl-like development patterns are associated with lower total water use. This result stems from the fact that low-density development patterns tend to be associated with increased conversion of irrigated agricultural land. Given the fact that irrigated agricultural land requires relatively more intensive water use when compared with urban land, lower density urbanization patterns can result in a reduction in total water use if the city expands into lands that are predominantly used for irrigated agriculture. My empirical approach combines fine-scale econometric and simulation methods in order to accommodate the spatial heterogeneity associated with land and water use in my study area, Oregon's Willamette Valley. In Chapter 3, I estimate a series of parcellevel hedonic property value models for land in developed, agricultural, and forest uses using a novel panel data set on land values for our study area, Oregon's Willamette Valley. Although the hedonic models are not an end in themselves, several policy applications are examined vis-a-vis the estimated property value relationships for each land use. First, for developed lands, I explore the effects of Oregon's comprehensive land-use plan, with specific focus on urban growth boundary designation, through the use of a variety of panel data estimators. Second, I analyze the relationship between agricultural land values and climatic influences, with particular emphasis on the interactions between the holding of irrigation rights and the effect of growing-season precipitation. The third application of the hedonic models pertains to how forest land values are influenced by transportation costs, represented by distance to the nearest processing mill, which change over time due to the large number of mill closures during my study period, partly in response to the old-growth harvest restrictions imposed by the Northwest Forest Plan. In Chapter 4, the estimated hedonic relationships are used to predict the values associated with land in selected and unselected uses in my land-use change data set, which comes from the US Geological Survey's Land Cover Trends (LCT) project. In a similar fashion to Bockstael (1996), I then use the land value predictions as explanatory variables in a set of discrete-choice urbanization models. In generating the predicted land values with the estimated hedonic relationships, I confront the sample selection issue inherent in applying the developed land hedonic model to lands that start in undeveloped uses using econometric methods suitable for panel data. I also compare the results generated with the coupled hedonic-urbanization approach with those from a reducedform model, which is more commonly found throughout the modern land economics literature. Additionally, using a Monte Carlo analysis, I illustrate the efficiency of the two-stage approach, and demonstrate how this property depends of the frequency of observed land development decisions. With my fully estimated econometric framework, I construct a spatially-explicit landscape simulation model in Chapter 5, which is used to analyze total water use over the period 2000-2070. The landscape simulations feature exogenous growth in population and income as the predominant drivers of urban land value dynamics. Agricultural water use is determined by spatial data on the location of irrigation water rights administered through the prior appropriation doctrine. Citywide urban demands are determined by the size of the city, demographic characteristics, water prices, pricing structure, and the demand for outdoor water use, which is influenced by precipitation. To generate my main results, I analyze three sets of scenarios in which I alter: (1) the area upon which land development is possible and (2) the city-specific population growth trajectory, and (3) the opportunity cost of land development for agricultural landowners. The first scenario set relates to the stringency of land-use regulations, which directly affects both the density of population growth and the urban composition of the city. Population growth, which is featured in the second set of scenarios, has several competing influences on total water use, among which are a direct influence on citywide residential water demand, and also the indirect effects that come about through the incentives to develop individual land parcels. In my third set of scenarios, I hold the land-use regulatory environment constant and impose permanent changes in precipitation patterns. Growing season precipitation indirectly influences total water use through its direct effect on the opportunity cost of land development for the owners of rainfed agricultural land. A novel feature of the simulation framework is that population density, which enters the developed land hedonic function, is treated as endogenous, as it is a function of development patterns and the permitted levels of development under different urban containment policies. Additionally, the simulation design is stochastic in that I treat land development decisions in a probabilistic fashion, facilitating an analysis of the distribution of results, including my main results for total water use, in each of the simulated scenarios. My results indicate that under situations that stimulate increased land development, the distribution of total water use is characterized by a lower mean if there is a sufficient amount of irrigated agricultural land in the vicinity of the city boundary, and if population growth is not prohibitively high. Further, the variance of total water use is decreasing in population density, as more sprawl-like development outcomes have a relatively wider array of potential spatial patterns associated with new land development. In the broadest sense, my dissertation highlights the interplay between population growth, climate change, land-use regulations, and the spatial patterns associated with both non-urban water endowments and new land development. The intermediate link that land-use change provides between climate change and population growth and water use has yet to be acknowledged and given proper treatment in the existing literature. Moreover, the connection between land-use change and water use emphasizes the inherent spatial heterogeneity in how water is used. Given the ubiquity of policies worldwide that impose location-specific constraints on water use, my analysis suggests that spatial considerations should be taken into account in subsequent studies that aim to analyze localized patterns of water use and how they may evolve in the future. Close

• 1746. [Article] Range-use estimation and encounter probability for juvenile Steller sea lions (Eumetopias jubatus) in the Prince William Sound-Kenai Fjords region of Alaska

  Range, areas of concentrated activity, and dispersal characteristics for juvenile Steller sea lions Eumetopias jubatus in the endangered western population (west of 144° W in the Gulf of Alaska) are poorly ...

  Citation × Citation Citation Abstract Copy Title: Range-use estimation and encounter probability for juvenile Steller sea lions (Eumetopias jubatus) in the Prince William Sound-Kenai Fjords region of Alaska Author: Meck, Stephen R. Range, areas of concentrated activity, and dispersal characteristics for juvenile Steller sea lions Eumetopias jubatus in the endangered western population (west of 144° W in the Gulf of Alaska) are poorly understood. This study quantified space use by analyzing post-release telemetric tracking data from satellite transmitters externally attached to n = 65 juvenile (12-25 months; 72.5 to 197.6 kg) Steller sea lions (SSLs) captured in Prince William Sound (60°38'N -147°8'W) or Resurrection Bay (60°2'N -149°22'W), Alaska, from 2003-2011. The analysis divided the sample population into 3 separate groups to quantify differences in distribution and movement. These groups included sex, the season when collected, and the release type (free ranging animals which were released immediately at the site of capture, and transient juveniles which were kept in captivity for up to 12 weeks as part of a larger ongoing research program). Range-use was first estimated by using the minimum convex polygon (MCP) approach, and then followed with a probabilistic kernel density estimation (KDE) to evaluate both individual and group utilization distributions (UDs). The LCV method was chosen as the smoothing algorithm for the KDE analysis as it provided biologically meaningful results pertaining to areas of concentrated activity (generally, haulout locations). The average distance traveled by study juveniles was 2,131 ± 424 km. The animals mass at release (F[subscript 1, 63] = 1.17, p = 0.28) and age (F[subscript 1, 63] = 0.033, p = 0.86) were not significant predictors of travel distance. Initial MCP results indicated the total area encompassed by all study SSLs was 92,017 km², excluding land mass. This area was heavily influenced by the only individual that crossed over the 144°W Meridian, the dividing line between the two distinct population segments. Without this individual, the remainder of the population (n = 64) fell into an area of 58,898 km². The MCP area was highly variable, with a geometric average of 1,623.6 km². Only the groups differentiated by season displayed any significant difference in area size, with the Spring/Summer (SS) groups MCP area (Mdn = 869.7 km²) being significantly less than that of the Fall/Winter (FW) group (Mdn = 3,202.2 km²), U = 330, p = 0.012, r = -0.31. This result was not related to the length of time the tag transmitted (H(2) = 49.65, p = 0.527), nor to the number of location fixes (H(2) = 62.77, p = 0.449). The KDE UD was less variable, with 50% of the population within a range of 324-1,387 km2 (mean=690.6 km²). There were no significant differences in area use associated with sex or release type (seasonally adjusted U = 124, p = 0.205, r = -0.16 and U = 87, p = 0.285, r = -0.13, respectively). However, there were significant differences in seasonal area use: U = 328, p = 0.011, r = -0.31. There was no relationship between the UD area and the amount of time the tag remained deployed (H(2) = 45.30, p = 0.698). The kernel home range (defined as 95% of space use) represented about 52.1% of the MCP range use, with areas designated as "core" (areas where the sea lions spent fully 50% of their time) making up only about 6.27% of the entire MCP range and about 11.8% of the entire kernel home range. Area use was relatively limited – at the population level, there were a total of 6 core areas which comprised 479 km². Core areas spanned a distance of less than 200 km from the most western point at the Chiswell Islands (59°35'N -149°36'W) to the most eastern point at Glacier Island (60°54'N -147°6'W). The observed differences in area use between seasons suggest a disparity in how juvenile SSLs utilize space and distribute themselves over the course of the year. Due to their age, this variation is less likely due to reproductive considerations and may reflect localized depletion of prey near preferred haul-out sites and/or changes in predation risk. Currently, management of the endangered western and threatened eastern population segments of the Steller sea lion are largely based on population trends derived from aerial survey counts and terrestrial-based count data. The likelihood of individuals to be detected during aerial surveys, and resulting correction factors to calculate overall population size from counts of hauled-out animals remain unknown. A kernel density estimation (KDE) analysis was performed to delineate boundaries around surveyed haulout locations within Prince William Sound-Kenai Fjords (PWS-KF). To closely approximate the time in which population abundance counts are conducted, only sea lions tracked during the spring/summer (SS) months (May 10-August 10) were chosen (n = 35). A multiple state model was constructed treating the satellite location data, if it fell within a specified spatiotemporal context, as a re-encounter within a mark-recapture framework. Information to determine a dry state was obtained from the tags time-at-depth (TAD) histograms. To generate an overall terrestrial detection probability 1) The animal must have been within a KDE derived core-area that coincided with a surveyed haulout site 2) it must have been dry and 3) it must have provided at least one position during the summer months, from roughly 11:00 AM-5:00 PM AKDT. A total of 10 transition states were selected from the data. Nine states corresponded to specific surveyed land locations, with the 10th, an "at-sea" location (> 3 km from land) included as a proxy for foraging behavior. A MLogit constraint was used to aid interpretation of the multi-modal likelihood surface, and a systematic model selection process employed as outlined by Lebreton & Pradel (2002). At the individual level, the juveniles released in the spring/summer months (n = 35) had 85.3% of the surveyed haulouts within PWS-KF encompass KDE-derived core areas (defined as 50% of space use). There was no difference in the number of surveyed haulouts encompassed by core areas between sexes (F[subscript 1, 33] << 0.001, p = 0.98). For animals held captive for up to 12 weeks, 33.3% returned to the original capture site. The majority of encounter probabilities (p) fell between 0.42 and 0.78 for the selected haulouts within PWS, with the exceptions being Grotto Island and Aialik Cape, which were lower (between 0.00-0.17). The at-sea (foraging) encounter probability was 0.66 (± 1 S.E. range 0.55-0.77). Most dry state probabilities fell between 0.08-0.38, with Glacier Island higher at 0.52, ± 1 S.E. range 0.49-0.55. The combined detection probability for hauled-out animals (the product of at haul-out and dry state probabilities), fell mostly between 0.08-0.28, with a distinct group (which included Grotto Island, Aialik Cape, and Procession Rocks) having values that averaged 0.01, with a cumulative range of ≈ 0.00-0.02 (± 1 S.E.). Due to gaps present within the mark-recapture data, it was not possible to run a goodness-of-fit test to validate model fit. Therefore, actual errors probably slightly exceed the reported standard errors and provide an approximation of uncertainties. Overall, the combined detection probabilities represent an effort to combine satellite location and wet-dry state telemetry and a kernel density analysis to quantify the terrestrial detection probability of a marine mammal within a multistate modeling framework, with the ultimate goal of developing a correction factor to account for haulout behavior at each of the surveyed locations included in the study. Title: Range-use estimation and encounter probability for juvenile Steller sea lions (Eumetopias jubatus) in the Prince William Sound-Kenai Fjords region of Alaska Author: Meck, Stephen R. Range, areas of concentrated activity, and dispersal characteristics for juvenile Steller sea lions Eumetopias jubatus in the endangered western population (west of 144° W in the Gulf of Alaska) are poorly understood. This study quantified space use by analyzing post-release telemetric tracking data from satellite transmitters externally attached to n = 65 juvenile (12-25 months; 72.5 to 197.6 kg) Steller sea lions (SSLs) captured in Prince William Sound (60°38'N -147°8'W) or Resurrection Bay (60°2'N -149°22'W), Alaska, from 2003-2011. The analysis divided the sample population into 3 separate groups to quantify differences in distribution and movement. These groups included sex, the season when collected, and the release type (free ranging animals which were released immediately at the site of capture, and transient juveniles which were kept in captivity for up to 12 weeks as part of a larger ongoing research program). Range-use was first estimated by using the minimum convex polygon (MCP) approach, and then followed with a probabilistic kernel density estimation (KDE) to evaluate both individual and group utilization distributions (UDs). The LCV method was chosen as the smoothing algorithm for the KDE analysis as it provided biologically meaningful results pertaining to areas of concentrated activity (generally, haulout locations). The average distance traveled by study juveniles was 2,131 ± 424 km. The animals mass at release (F[subscript 1, 63] = 1.17, p = 0.28) and age (F[subscript 1, 63] = 0.033, p = 0.86) were not significant predictors of travel distance. Initial MCP results indicated the total area encompassed by all study SSLs was 92,017 km², excluding land mass. This area was heavily influenced by the only individual that crossed over the 144°W Meridian, the dividing line between the two distinct population segments. Without this individual, the remainder of the population (n = 64) fell into an area of 58,898 km². The MCP area was highly variable, with a geometric average of 1,623.6 km². Only the groups differentiated by season displayed any significant difference in area size, with the Spring/Summer (SS) groups MCP area (Mdn = 869.7 km²) being significantly less than that of the Fall/Winter (FW) group (Mdn = 3,202.2 km²), U = 330, p = 0.012, r = -0.31. This result was not related to the length of time the tag transmitted (H(2) = 49.65, p = 0.527), nor to the number of location fixes (H(2) = 62.77, p = 0.449). The KDE UD was less variable, with 50% of the population within a range of 324-1,387 km2 (mean=690.6 km²). There were no significant differences in area use associated with sex or release type (seasonally adjusted U = 124, p = 0.205, r = -0.16 and U = 87, p = 0.285, r = -0.13, respectively). However, there were significant differences in seasonal area use: U = 328, p = 0.011, r = -0.31. There was no relationship between the UD area and the amount of time the tag remained deployed (H(2) = 45.30, p = 0.698). The kernel home range (defined as 95% of space use) represented about 52.1% of the MCP range use, with areas designated as "core" (areas where the sea lions spent fully 50% of their time) making up only about 6.27% of the entire MCP range and about 11.8% of the entire kernel home range. Area use was relatively limited – at the population level, there were a total of 6 core areas which comprised 479 km². Core areas spanned a distance of less than 200 km from the most western point at the Chiswell Islands (59°35'N -149°36'W) to the most eastern point at Glacier Island (60°54'N -147°6'W). The observed differences in area use between seasons suggest a disparity in how juvenile SSLs utilize space and distribute themselves over the course of the year. Due to their age, this variation is less likely due to reproductive considerations and may reflect localized depletion of prey near preferred haul-out sites and/or changes in predation risk. Currently, management of the endangered western and threatened eastern population segments of the Steller sea lion are largely based on population trends derived from aerial survey counts and terrestrial-based count data. The likelihood of individuals to be detected during aerial surveys, and resulting correction factors to calculate overall population size from counts of hauled-out animals remain unknown. A kernel density estimation (KDE) analysis was performed to delineate boundaries around surveyed haulout locations within Prince William Sound-Kenai Fjords (PWS-KF). To closely approximate the time in which population abundance counts are conducted, only sea lions tracked during the spring/summer (SS) months (May 10-August 10) were chosen (n = 35). A multiple state model was constructed treating the satellite location data, if it fell within a specified spatiotemporal context, as a re-encounter within a mark-recapture framework. Information to determine a dry state was obtained from the tags time-at-depth (TAD) histograms. To generate an overall terrestrial detection probability 1) The animal must have been within a KDE derived core-area that coincided with a surveyed haulout site 2) it must have been dry and 3) it must have provided at least one position during the summer months, from roughly 11:00 AM-5:00 PM AKDT. A total of 10 transition states were selected from the data. Nine states corresponded to specific surveyed land locations, with the 10th, an "at-sea" location (> 3 km from land) included as a proxy for foraging behavior. A MLogit constraint was used to aid interpretation of the multi-modal likelihood surface, and a systematic model selection process employed as outlined by Lebreton & Pradel (2002). At the individual level, the juveniles released in the spring/summer months (n = 35) had 85.3% of the surveyed haulouts within PWS-KF encompass KDE-derived core areas (defined as 50% of space use). There was no difference in the number of surveyed haulouts encompassed by core areas between sexes (F[subscript 1, 33] << 0.001, p = 0.98). For animals held captive for up to 12 weeks, 33.3% returned to the original capture site. The majority of encounter probabilities (p) fell between 0.42 and 0.78 for the selected haulouts within PWS, with the exceptions being Grotto Island and Aialik Cape, which were lower (between 0.00-0.17). The at-sea (foraging) encounter probability was 0.66 (± 1 S.E. range 0.55-0.77). Most dry state probabilities fell between 0.08-0.38, with Glacier Island higher at 0.52, ± 1 S.E. range 0.49-0.55. The combined detection probability for hauled-out animals (the product of at haul-out and dry state probabilities), fell mostly between 0.08-0.28, with a distinct group (which included Grotto Island, Aialik Cape, and Procession Rocks) having values that averaged 0.01, with a cumulative range of ≈ 0.00-0.02 (± 1 S.E.). Due to gaps present within the mark-recapture data, it was not possible to run a goodness-of-fit test to validate model fit. Therefore, actual errors probably slightly exceed the reported standard errors and provide an approximation of uncertainties. Overall, the combined detection probabilities represent an effort to combine satellite location and wet-dry state telemetry and a kernel density analysis to quantify the terrestrial detection probability of a marine mammal within a multistate modeling framework, with the ultimate goal of developing a correction factor to account for haulout behavior at each of the surveyed locations included in the study. Close

• 1747. [Article] The influence of climate change and restoration on stream temperature

  Water temperature is an essential property of a stream. Temperature regulates physical and biochemical processes in aquatic habitats. Various factors related to climatic conditions, landscape characteristics, ...

  Citation × Citation Citation Abstract Copy Title: The influence of climate change and restoration on stream temperature Author: Diabat, Mousa Water temperature is an essential property of a stream. Temperature regulates physical and biochemical processes in aquatic habitats. Various factors related to climatic conditions, landscape characteristics, and channel structure directly influence stream temperature. Numerous studies indicate that increased average air temperature during the past century has led to stream warming across the world. The trend of stream warming was also present in spring-fed watersheds, where summer flow has decreased. In addition, anthropogenic practices that alter the natural landscape and channel structure, such as forest management, agriculture, and mining contributed to stream warming. For example, deforested and unshaded stream reaches or dredged channels were warmer than shaded reaches and meandering streams. Stream temperatures in North American lotic habitats are of a specific concern due to their significant economic, cultural, and ecological value. With climate projections indicating that air temperature will only continue to rise throughout the 21st century, cold- or cool-water organisms, especially fishes, will be affected. Therefore, there is a strong need to better understand the impacts of changing climate, riparian landscape, and channel structure on a stream's heat budget. This may assist in restoring the historic thermal regime in impacted sites and mitigating the impacts of future climate change. This study looks into the relative influences of the different factors on a stream's heat budget with three manuscripts: one on stream temperature response to diel timing of air warming, one on stream temperature response to changes in air temperature, flow, and riparian vegetation, and one on stream temperature response to air warming and channel reconstruction. I used the software Heat Source version 8.05 to simulate stream temperature for all three analyses along the Middle Fork John Day River, Oregon USA. Two of the manuscripts were applied to an upper 37 km section of the Middle Fork John Day River (presented in chapter 2 and 3), where the third manuscript was applied to a 1.5-km section. The sensitivity analysis of stream temperature response to diel timing of air warming (Chapter 2: Diel Timing of Warmer Air under Climate Change Affects Magnitude, Timing, and Duration of Stream Temperature Change) was based on scenarios representing uniform air warming over the diel period, daytime warming, and nighttime warming. Uniform warming of air temperature is a simple representation of increases in the average daily or monthly temperatures generated by the 'delta method'. The delta method relies on adding a constant value to the air temperature time-series data. This constant value is the difference (delta) between base case average air temperatures and the projected one. Scenarios of daytime or nighttime warming represent conditions under which most of the warming of the air occurs during the daytime or the nighttime, respectively. I simulated the stream temperature response to warmer air conditions of +2 °C and +4 °C in daily average for all three cases of air warming conditions. The three cases of different diel distributions of air warming generated 7-day average daily maximum stream temperature (7DADM) increases of approximately +1.8 °C ± 0.1 °C at the downstream end of the study section relative to the base case. In most parts of the reach, the three distributions of air warming generated different ranges of stream temperatures, different 7DADM values, different durations of stream temperature changes, and different average daily temperatures. Changes of stream temperature were out of phase with imposed changes of air temperature. Therefore, nighttime warming of air temperatures would cause the greatest increase in maximum daily stream temperature, which typically occurs during the daytime. The sensitivity analysis of the relative influences of changes in air temperature, stream flow, and riparian vegetation on stream temperature (Chapter 3: Assessing Stream Temperature Response to Cumulative Influence of Changing Air Temperature, Flow, and Riparian Vegetation). This study summarized stream temperature simulation in 36 scenarios representing possible manifestations of 21st century climate conditions and land management strategies. In addition to existing conditions (base case) of flow, air temperature, and riparian vegetation, scenarios consisted of: two air temperature increases of 2 °C and 4 °C, two stream flow variations of +30% and -30%, three spatially uniform riparian vegetation conditions that create averages of effective shade 7%, 34%, and 79%, in addition to 14% for base case conditions. Results suggest that variation in riparian vegetation was the dominant factor influencing stream temperature because it regulates incoming shortwave radiation, the largest heat input to the stream, while variation in stream flow has a negligible influence. Results indicated that increasing the effective shade along the study section, particularly in the currently unshaded sections, could mitigate the influence of increasing air temperature, and would reduce stream temperature maxima below current values even under future climate conditions of warmer air. With the small influence it had, increasing stream flow reduced the 7DADM under low shade conditions. However, increasing stream flow showed counterintuitive results as it contributed to increasing stream temperature maxima when the stream was heavily shaded. The applied study examined the stream temperature response to restoration practices and their potential to mitigate the influence of warmer air conditions (Chapter 4: Estimating Stream Temperature Response to Restoring Channel and Riparian Vegetation and the Potential to Mitigate Warmer Air Conditions). This study focused on a 1.5 km section along the upper part of the Middle Fork John Day River that was modified due to past anthropogenic activities of mining for gold and timber harvest. Currently, the riparian vegetation of the study site is mostly shrubs and stands of short trees. Restoration designs call for the restoration of both the channel structure and replanting the riparian vegetation. Simulation results showed that the 7DADM was higher in the restored channel than the existing channel with both conditions of low and high effective shade conditions. However, a combined restoration practice of channel reconstruction and medium effective shade conditions reduced stream temperature maxima more than restoring riparian vegetation alone. In addition, results showed that restoring riparian vegetation was sufficient to mitigate the influence of warmer air on stream temperature, while restoring the channel alone is not. Heat budget analysis showed that heat accumulation during the daytime increased in the restored channel, which was longer, narrower, and deeper than the existing channel. It is important to emphasize that stream temperature is one of many goals that restoration activities aim to improve. Furthermore, differences in 7DADM among the different scenarios of restoration are negligible. Such small differences could hardly be measure. While this study examined a short section of 1.5 km, longer stream sections may increase the differences in 7DADM. Primary conclusions of this study are: 1) daily maxima of stream temperature will increase in response to increased air temperature regardless of the distribution of air warming during the diel cycle; 2) nighttime air warming caused a greater increase in stream temperature maximum than daytime warming; 3) riparian vegetation was the dominant factor on stream's heat budget, more than air temperature or stream flow; 4) restoring riparian vegetation mitigated the influence of warmer air; 5) restoring channel structure alone was not sufficient to lower temperature maxima; and 6) restoration project was most successful in improving degraded stream temperature when combined with channel reconstruction and improved riparian shade. Title: The influence of climate change and restoration on stream temperature Author: Diabat, Mousa Water temperature is an essential property of a stream. Temperature regulates physical and biochemical processes in aquatic habitats. Various factors related to climatic conditions, landscape characteristics, and channel structure directly influence stream temperature. Numerous studies indicate that increased average air temperature during the past century has led to stream warming across the world. The trend of stream warming was also present in spring-fed watersheds, where summer flow has decreased. In addition, anthropogenic practices that alter the natural landscape and channel structure, such as forest management, agriculture, and mining contributed to stream warming. For example, deforested and unshaded stream reaches or dredged channels were warmer than shaded reaches and meandering streams. Stream temperatures in North American lotic habitats are of a specific concern due to their significant economic, cultural, and ecological value. With climate projections indicating that air temperature will only continue to rise throughout the 21st century, cold- or cool-water organisms, especially fishes, will be affected. Therefore, there is a strong need to better understand the impacts of changing climate, riparian landscape, and channel structure on a stream's heat budget. This may assist in restoring the historic thermal regime in impacted sites and mitigating the impacts of future climate change. This study looks into the relative influences of the different factors on a stream's heat budget with three manuscripts: one on stream temperature response to diel timing of air warming, one on stream temperature response to changes in air temperature, flow, and riparian vegetation, and one on stream temperature response to air warming and channel reconstruction. I used the software Heat Source version 8.05 to simulate stream temperature for all three analyses along the Middle Fork John Day River, Oregon USA. Two of the manuscripts were applied to an upper 37 km section of the Middle Fork John Day River (presented in chapter 2 and 3), where the third manuscript was applied to a 1.5-km section. The sensitivity analysis of stream temperature response to diel timing of air warming (Chapter 2: Diel Timing of Warmer Air under Climate Change Affects Magnitude, Timing, and Duration of Stream Temperature Change) was based on scenarios representing uniform air warming over the diel period, daytime warming, and nighttime warming. Uniform warming of air temperature is a simple representation of increases in the average daily or monthly temperatures generated by the 'delta method'. The delta method relies on adding a constant value to the air temperature time-series data. This constant value is the difference (delta) between base case average air temperatures and the projected one. Scenarios of daytime or nighttime warming represent conditions under which most of the warming of the air occurs during the daytime or the nighttime, respectively. I simulated the stream temperature response to warmer air conditions of +2 °C and +4 °C in daily average for all three cases of air warming conditions. The three cases of different diel distributions of air warming generated 7-day average daily maximum stream temperature (7DADM) increases of approximately +1.8 °C ± 0.1 °C at the downstream end of the study section relative to the base case. In most parts of the reach, the three distributions of air warming generated different ranges of stream temperatures, different 7DADM values, different durations of stream temperature changes, and different average daily temperatures. Changes of stream temperature were out of phase with imposed changes of air temperature. Therefore, nighttime warming of air temperatures would cause the greatest increase in maximum daily stream temperature, which typically occurs during the daytime. The sensitivity analysis of the relative influences of changes in air temperature, stream flow, and riparian vegetation on stream temperature (Chapter 3: Assessing Stream Temperature Response to Cumulative Influence of Changing Air Temperature, Flow, and Riparian Vegetation). This study summarized stream temperature simulation in 36 scenarios representing possible manifestations of 21st century climate conditions and land management strategies. In addition to existing conditions (base case) of flow, air temperature, and riparian vegetation, scenarios consisted of: two air temperature increases of 2 °C and 4 °C, two stream flow variations of +30% and -30%, three spatially uniform riparian vegetation conditions that create averages of effective shade 7%, 34%, and 79%, in addition to 14% for base case conditions. Results suggest that variation in riparian vegetation was the dominant factor influencing stream temperature because it regulates incoming shortwave radiation, the largest heat input to the stream, while variation in stream flow has a negligible influence. Results indicated that increasing the effective shade along the study section, particularly in the currently unshaded sections, could mitigate the influence of increasing air temperature, and would reduce stream temperature maxima below current values even under future climate conditions of warmer air. With the small influence it had, increasing stream flow reduced the 7DADM under low shade conditions. However, increasing stream flow showed counterintuitive results as it contributed to increasing stream temperature maxima when the stream was heavily shaded. The applied study examined the stream temperature response to restoration practices and their potential to mitigate the influence of warmer air conditions (Chapter 4: Estimating Stream Temperature Response to Restoring Channel and Riparian Vegetation and the Potential to Mitigate Warmer Air Conditions). This study focused on a 1.5 km section along the upper part of the Middle Fork John Day River that was modified due to past anthropogenic activities of mining for gold and timber harvest. Currently, the riparian vegetation of the study site is mostly shrubs and stands of short trees. Restoration designs call for the restoration of both the channel structure and replanting the riparian vegetation. Simulation results showed that the 7DADM was higher in the restored channel than the existing channel with both conditions of low and high effective shade conditions. However, a combined restoration practice of channel reconstruction and medium effective shade conditions reduced stream temperature maxima more than restoring riparian vegetation alone. In addition, results showed that restoring riparian vegetation was sufficient to mitigate the influence of warmer air on stream temperature, while restoring the channel alone is not. Heat budget analysis showed that heat accumulation during the daytime increased in the restored channel, which was longer, narrower, and deeper than the existing channel. It is important to emphasize that stream temperature is one of many goals that restoration activities aim to improve. Furthermore, differences in 7DADM among the different scenarios of restoration are negligible. Such small differences could hardly be measure. While this study examined a short section of 1.5 km, longer stream sections may increase the differences in 7DADM. Primary conclusions of this study are: 1) daily maxima of stream temperature will increase in response to increased air temperature regardless of the distribution of air warming during the diel cycle; 2) nighttime air warming caused a greater increase in stream temperature maximum than daytime warming; 3) riparian vegetation was the dominant factor on stream's heat budget, more than air temperature or stream flow; 4) restoring riparian vegetation mitigated the influence of warmer air; 5) restoring channel structure alone was not sufficient to lower temperature maxima; and 6) restoration project was most successful in improving degraded stream temperature when combined with channel reconstruction and improved riparian shade. Close

• 1748. [Article] The Geology and Geochemistry of the Haquira East Porphyry Copper Deposit of Southern Peru : Insights on the Timing, Temperature and Lifespan of the Magmatic-hydrothermal Alteration and Mineralization

  This dissertation is informally divided into three major sections. In the first section (Chapter 2) I use data from field mapping, isotopic geochronology, whole rock geochemistry and trace element concentrations ...

  Citation × Citation Citation Abstract Copy Title: The Geology and Geochemistry of the Haquira East Porphyry Copper Deposit of Southern Peru : Insights on the Timing, Temperature and Lifespan of the Magmatic-hydrothermal Alteration and Mineralization Author: Cernuschi Rodilosso, Federico This dissertation is informally divided into three major sections. In the first section (Chapter 2) I use data from field mapping, isotopic geochronology, whole rock geochemistry and trace element concentrations in zircons to examine the petrology, geochemistry and ages of the Haquira East porphyry copper deposit of southern Peru. In the second section (Chapters 3 - 6) I investigate the timing, temperature, zonation and lifespan of the magmatic-hydrothermal alteration and Cu-Mo mineralization by applying field mapping, whole rock geochemistry, petrography, geothermometry, spectral, X-ray and cathodoluminiscense imaging of rock samples. The timescales of the magmatic-hydrothermal system was constrained by isotopic dating, diffusion of titanium in quartz and the novel approach of oxygen diffusion via δ¹⁸O of quartz analyzed by secondary ion mass spectrometry. These data are also used construct cross-sections and 3D models. In the final section (Chapter 7) I describe the production and evaluation of a calibration for portable X-ray spectrometers that could potentially be applied to further investigate porphyry copper deposits. Haquira East is a moderate grade porphyry copper-molybdenum-gold deposit (688 Mt ore at 0.59 wt. % Cu, containing 4.7 Mt Cu, 37,000 t Mo and 0.9 M oz Au) in the Eocene-Oligocene Andahuaylas-Yauri porphyry belt of southern Peru. Based on a Re/Os age of molybdenite, the copper and molybdenum mineralization and hydrothermal alteration at Haquira East formed at ~33.85 Ma. These ores are associated with dominantly granodioritic intrusions that range from 34.5 to 33.5 Ma in age and represent some of the youngest intrusions of the Andahuaylas-Yauri batholith between 40 and 32 Ma. In this study, new U-Pb zircon ages of these intrusions ages were determined via laser ablation inductively coupled mass spectroscopy (LA-ICP-MS¬) and sensitive high resolution ion microprobe in reverse geometry (SHRIMP-RG). At Haquira East, the regional Eocene-Oligocene shortening of the Incaic orogeny resulted in the folding of Jurassic-Cretaceous meta-sedimentary rock into the northwest-trending and northeast-overturned Tocone syncline that is associated with northwest-striking and southwest-dipping thrust faults. The magmatism was synchronous with the deformation and began with the ~34.5 Ma andesitic to dacitic Lahuani sills and was followed by the ~34.2 to 33.5 Ma Haquira granodiorite stock and the slightly younger, narrow and subvertical Haquira porphyry dikes of similar composition. Several sets of Haquira porphyry dikes were emplaced synchronously with the porphyry copper and molybdenum mineralization, veining and K-silicate hydrothermal alteration. At the waning stages of the magmatism (~33.5), the dacitic Pararani porphyry dikes were emplaced along a north-south strike and closely followed in time with D veins, sericitic halos and sericitically-altered hydrothermal breccias. Whole-rock trace element modeling indicates that the Haquira East magmas originated in a garnet-bearing basaltic-andesite to andesite zone of melt-assimilation-storage-hybridization (MASH) in the lower crust below ~25 km depth. Andesite melts from the MASH zone were injected into an inferred granodiorite magma chamber at ~10km depth beneath Haquira East, where the oxidized and water-rich magma fractionated hornblende and small amounts of plagioclase, together with traces of titanite, apatite, zircon and magnetite. Intrusions sourced in this chamber have enrichments in Sr/Y (>60) and V/Sc (>12), depletions in the light rare earth elements (REE) and high mid-REE/heavy-REE ratios inherited from melts derived from the MASH zone where garnet is residual. Similarly, the intrusions that were emplaced closely in time with the mineralization have high Eu[subscript N]/Eu[subscript N]* (0.4 to 0.8) and Ce[subscript N]/Ce[subscript N]* (200 to 5000) in zircon compared to older intrusions (LA-ICP-MS, and SHRIMP-RG) further evidencing the high oxidation state and water content of the magma. New core logging observations, ICP-MS whole rock geochemical data and short wave infrared spectroscopy data document the sequence and spatial distribution of veins, hydrothermal alteration zones and Cu-Mo-bearing sulfide ore zones and are summarized in cross-sections and three-dimensional models. From oldest to youngest, the sequence of veins consists of biotite veins/micro-breccias, aplite dikes, deep quartz (DQ) veins, actinolite veins with plagioclase halos and epidote veins, early dark micaceous (EDM) halos with bornite-chalcopyrite, Cu-sulfide±quartz veinlets with chalcopyrite and/or bornite, banded molybdenite-quartz (BMQ) veins, B-type quartz-bornite-chalcopyrite veins, D-type pyrite-quartz-sericite veins with sericitic halos, and fractures with green and white intermediate argillic halos containing mixtures of illite-smectite-chlorite-kaolinite ± pyrite. The areas with the highest density of EDM halos constitute the high-grade copper ore. Scanning electron microscopy imaging (QEMSCAN) have been used to identifiy mineralogy, textures and zoning of hydrothermal alteration zones. The EDM halos are formed by hydrothermal biotite, muscovite, K-feldspar, with rare quartz and corundum replacing magmatic plagioclase and hornblende and carry up to 10-15 volume % disseminated bornite and chalcopyrite. Later BMQ veins host the high-grade molybdenum ore, whereas late B veins contribute both copper and molybdenum to the ores. The copper ore shell forms a continuous high-grade ore zone (>0.5 wt. %) in the Haquira stock, but is lower grade where it projects into the relatively non-reactive meta-sedimentary, mostly quartzite, wall rock, likely as a result of a limited supply of iron to enable copper-iron sulfide precipitation. In contrast, molybdenite mineralization forms a roughly symmetric shell overlapping both the stock and quartzite with an axis of symmetry located along the southwest flank of the Haquira granodiorite stock. The abundance of EDM halos, lack of A veins and the dearth of unmixed fluid inclusion assemblages in quartz veins and prescense of two phase (liquid + vapor) fluid inclusions (P>1.5 kbar) suggest that Haquira East was emplaced at significant depths. The emplacement depth of Haquira is estimated at ~10 km, at greater depth than shallower and outcropping Acojasa intrusion to the south, emplaced at ~ 8 km according to hornblende barometry (~2.0 ± 0.5 kb). The veining, hydrothermal alteration and mineralization formed at this depth magmatic hydrothermal fluid was released from an inferred magmatic cupola, hydro-fractured the wall rock and depressurized from ~3 kb at lithostatic pressure to >1.2 kb at close to hydrostatic pressure without unmixing into a vapor and brine phase. The temperature evolution of the magmatic-hydrothermal system was estimated by mineral phase equilibria and the application of different geothermometers. For TitaniQ geothermometry, Ti-in-quartz of veins and dikes was measured by electron microprobe (EMP) and LA-ICP-MS (1 ppm to > 100 ppm) on samples that were previously imaged by secondary electron microscope cathodoluminescense, Temperatures were also estimated through Ti-in-zircon (2 ppm to 13 ppm, via SHRIMP-RG), Ti-in-biotite (~1.0 to 2.3wt.%, via EMP) and the δ³⁴S compositions of pyrite-anhydrite and chalcopyrite-anhydrite pairs (-1.4 ‰ to -0.1‰ and 7.5 ‰ to 10.2‰ respectively). Porphyry dikes, aplites and DQ veins formed first between ~720ºC and 650ºC. Copper was introduced later in EDM halos at ~500ºC and was followed by molybdenite in BMQ veins at ~650ºC during a thermal reversal. A second stage of copper and molybdenum was introduced in B veins at ~550°C. Late D veins with pyrite and sericite formed first at ~450ºC and later at ~350ºC. Diffusion modeling of both Ti (EMP) and δ¹⁸O gradients (via secondary ion mass spectrometry, ~10.7 ‰ to ~12.7‰) across initially abrupt quartz growth boundaries yields a calculated maximum lifespan for the Haquira East porphyry of 170,000 years for the period from initial fluid injection at >650 ºC to cooling below ~ 350 ºC. However, the high-grade copper and molybdenum ore formed relatively rapidly in less than 30,000 years. In the last chapter of this dissertation two calibrations were produced and tested for a Bruker Tracer IV portable X-ray fluorescence portable spectrometer (pXRF). Concentrations of Al₂O₃, CaO, FeO*, K₂O, MnO, TiO₂ and, in lesser degree, SiO₂ were accurately reproduced together with Cr, Cu, Nb, Ni, Sr, Y, Zr and less accurately V in powdered basaltic samples, and Nb, Pb, Rb, Sr, Y, Zn, Zr and, less accurately, Ba in powdered rhyolitic samples. The pXRF is particularly reliable for measuring relatively immobile elements (e.g. Nb, Zr, Ti and Y), which are often resistant to hydrothermal alteration and weathering. Therefore pXRFs may be useful for lithogeochemical mapping of hydrothermally altered rocks that are zoned around porphyry copper deposits. Title: The Geology and Geochemistry of the Haquira East Porphyry Copper Deposit of Southern Peru : Insights on the Timing, Temperature and Lifespan of the Magmatic-hydrothermal Alteration and Mineralization Author: Cernuschi Rodilosso, Federico This dissertation is informally divided into three major sections. In the first section (Chapter 2) I use data from field mapping, isotopic geochronology, whole rock geochemistry and trace element concentrations in zircons to examine the petrology, geochemistry and ages of the Haquira East porphyry copper deposit of southern Peru. In the second section (Chapters 3 - 6) I investigate the timing, temperature, zonation and lifespan of the magmatic-hydrothermal alteration and Cu-Mo mineralization by applying field mapping, whole rock geochemistry, petrography, geothermometry, spectral, X-ray and cathodoluminiscense imaging of rock samples. The timescales of the magmatic-hydrothermal system was constrained by isotopic dating, diffusion of titanium in quartz and the novel approach of oxygen diffusion via δ¹⁸O of quartz analyzed by secondary ion mass spectrometry. These data are also used construct cross-sections and 3D models. In the final section (Chapter 7) I describe the production and evaluation of a calibration for portable X-ray spectrometers that could potentially be applied to further investigate porphyry copper deposits. Haquira East is a moderate grade porphyry copper-molybdenum-gold deposit (688 Mt ore at 0.59 wt. % Cu, containing 4.7 Mt Cu, 37,000 t Mo and 0.9 M oz Au) in the Eocene-Oligocene Andahuaylas-Yauri porphyry belt of southern Peru. Based on a Re/Os age of molybdenite, the copper and molybdenum mineralization and hydrothermal alteration at Haquira East formed at ~33.85 Ma. These ores are associated with dominantly granodioritic intrusions that range from 34.5 to 33.5 Ma in age and represent some of the youngest intrusions of the Andahuaylas-Yauri batholith between 40 and 32 Ma. In this study, new U-Pb zircon ages of these intrusions ages were determined via laser ablation inductively coupled mass spectroscopy (LA-ICP-MS¬) and sensitive high resolution ion microprobe in reverse geometry (SHRIMP-RG). At Haquira East, the regional Eocene-Oligocene shortening of the Incaic orogeny resulted in the folding of Jurassic-Cretaceous meta-sedimentary rock into the northwest-trending and northeast-overturned Tocone syncline that is associated with northwest-striking and southwest-dipping thrust faults. The magmatism was synchronous with the deformation and began with the ~34.5 Ma andesitic to dacitic Lahuani sills and was followed by the ~34.2 to 33.5 Ma Haquira granodiorite stock and the slightly younger, narrow and subvertical Haquira porphyry dikes of similar composition. Several sets of Haquira porphyry dikes were emplaced synchronously with the porphyry copper and molybdenum mineralization, veining and K-silicate hydrothermal alteration. At the waning stages of the magmatism (~33.5), the dacitic Pararani porphyry dikes were emplaced along a north-south strike and closely followed in time with D veins, sericitic halos and sericitically-altered hydrothermal breccias. Whole-rock trace element modeling indicates that the Haquira East magmas originated in a garnet-bearing basaltic-andesite to andesite zone of melt-assimilation-storage-hybridization (MASH) in the lower crust below ~25 km depth. Andesite melts from the MASH zone were injected into an inferred granodiorite magma chamber at ~10km depth beneath Haquira East, where the oxidized and water-rich magma fractionated hornblende and small amounts of plagioclase, together with traces of titanite, apatite, zircon and magnetite. Intrusions sourced in this chamber have enrichments in Sr/Y (>60) and V/Sc (>12), depletions in the light rare earth elements (REE) and high mid-REE/heavy-REE ratios inherited from melts derived from the MASH zone where garnet is residual. Similarly, the intrusions that were emplaced closely in time with the mineralization have high Eu[subscript N]/Eu[subscript N]* (0.4 to 0.8) and Ce[subscript N]/Ce[subscript N]* (200 to 5000) in zircon compared to older intrusions (LA-ICP-MS, and SHRIMP-RG) further evidencing the high oxidation state and water content of the magma. New core logging observations, ICP-MS whole rock geochemical data and short wave infrared spectroscopy data document the sequence and spatial distribution of veins, hydrothermal alteration zones and Cu-Mo-bearing sulfide ore zones and are summarized in cross-sections and three-dimensional models. From oldest to youngest, the sequence of veins consists of biotite veins/micro-breccias, aplite dikes, deep quartz (DQ) veins, actinolite veins with plagioclase halos and epidote veins, early dark micaceous (EDM) halos with bornite-chalcopyrite, Cu-sulfide±quartz veinlets with chalcopyrite and/or bornite, banded molybdenite-quartz (BMQ) veins, B-type quartz-bornite-chalcopyrite veins, D-type pyrite-quartz-sericite veins with sericitic halos, and fractures with green and white intermediate argillic halos containing mixtures of illite-smectite-chlorite-kaolinite ± pyrite. The areas with the highest density of EDM halos constitute the high-grade copper ore. Scanning electron microscopy imaging (QEMSCAN) have been used to identifiy mineralogy, textures and zoning of hydrothermal alteration zones. The EDM halos are formed by hydrothermal biotite, muscovite, K-feldspar, with rare quartz and corundum replacing magmatic plagioclase and hornblende and carry up to 10-15 volume % disseminated bornite and chalcopyrite. Later BMQ veins host the high-grade molybdenum ore, whereas late B veins contribute both copper and molybdenum to the ores. The copper ore shell forms a continuous high-grade ore zone (>0.5 wt. %) in the Haquira stock, but is lower grade where it projects into the relatively non-reactive meta-sedimentary, mostly quartzite, wall rock, likely as a result of a limited supply of iron to enable copper-iron sulfide precipitation. In contrast, molybdenite mineralization forms a roughly symmetric shell overlapping both the stock and quartzite with an axis of symmetry located along the southwest flank of the Haquira granodiorite stock. The abundance of EDM halos, lack of A veins and the dearth of unmixed fluid inclusion assemblages in quartz veins and prescense of two phase (liquid + vapor) fluid inclusions (P>1.5 kbar) suggest that Haquira East was emplaced at significant depths. The emplacement depth of Haquira is estimated at ~10 km, at greater depth than shallower and outcropping Acojasa intrusion to the south, emplaced at ~ 8 km according to hornblende barometry (~2.0 ± 0.5 kb). The veining, hydrothermal alteration and mineralization formed at this depth magmatic hydrothermal fluid was released from an inferred magmatic cupola, hydro-fractured the wall rock and depressurized from ~3 kb at lithostatic pressure to >1.2 kb at close to hydrostatic pressure without unmixing into a vapor and brine phase. The temperature evolution of the magmatic-hydrothermal system was estimated by mineral phase equilibria and the application of different geothermometers. For TitaniQ geothermometry, Ti-in-quartz of veins and dikes was measured by electron microprobe (EMP) and LA-ICP-MS (1 ppm to > 100 ppm) on samples that were previously imaged by secondary electron microscope cathodoluminescense, Temperatures were also estimated through Ti-in-zircon (2 ppm to 13 ppm, via SHRIMP-RG), Ti-in-biotite (~1.0 to 2.3wt.%, via EMP) and the δ³⁴S compositions of pyrite-anhydrite and chalcopyrite-anhydrite pairs (-1.4 ‰ to -0.1‰ and 7.5 ‰ to 10.2‰ respectively). Porphyry dikes, aplites and DQ veins formed first between ~720ºC and 650ºC. Copper was introduced later in EDM halos at ~500ºC and was followed by molybdenite in BMQ veins at ~650ºC during a thermal reversal. A second stage of copper and molybdenum was introduced in B veins at ~550°C. Late D veins with pyrite and sericite formed first at ~450ºC and later at ~350ºC. Diffusion modeling of both Ti (EMP) and δ¹⁸O gradients (via secondary ion mass spectrometry, ~10.7 ‰ to ~12.7‰) across initially abrupt quartz growth boundaries yields a calculated maximum lifespan for the Haquira East porphyry of 170,000 years for the period from initial fluid injection at >650 ºC to cooling below ~ 350 ºC. However, the high-grade copper and molybdenum ore formed relatively rapidly in less than 30,000 years. In the last chapter of this dissertation two calibrations were produced and tested for a Bruker Tracer IV portable X-ray fluorescence portable spectrometer (pXRF). Concentrations of Al₂O₃, CaO, FeO*, K₂O, MnO, TiO₂ and, in lesser degree, SiO₂ were accurately reproduced together with Cr, Cu, Nb, Ni, Sr, Y, Zr and less accurately V in powdered basaltic samples, and Nb, Pb, Rb, Sr, Y, Zn, Zr and, less accurately, Ba in powdered rhyolitic samples. The pXRF is particularly reliable for measuring relatively immobile elements (e.g. Nb, Zr, Ti and Y), which are often resistant to hydrothermal alteration and weathering. Therefore pXRFs may be useful for lithogeochemical mapping of hydrothermally altered rocks that are zoned around porphyry copper deposits. Close

• 1749. [Article] Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin

  Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has ...

  Citation × Citation Citation Abstract Copy Title: Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin Author: Eiler, John H. Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has raised concerns over the future status of the returns, and severely impacted commercial and subsistence fisheries within the drainage. Management is further complicated by the mixed-stock composition of the run, the presence of other temporally similar salmon species, and the need to equitably allocate harvests between the numerous fisheries and user groups scattered throughout the basin. Detailed information is needed on Chinook salmon run characteristics to better understand and manage the returns, and facilitate conservation efforts. However, this goal is exacerbated by the massive size and remote nature of the basin, the large number of highly mobile fish, and the compressed timing of the run. To address these challenges, radio telemetry was used to determine the stock composition and spawning distribution of the returns, and the migratory characteristics of the fish. The migratory patterns exhibited by returning salmon provide a number of insights into the status of the run. Since the Yukon River is essentially free-flowing (i.e., not regulated), this study also presented an opportunity to document the distribution and upriver movements of large returns of wild Chinook salmon under natural conditions. During 2002-2004, returning adult Chinook salmon were captured in the lower Yukon River (approximately 300 km upriver from the river mouth), tagged with radio transmitters, and tracked upriver using remote tracking stations located on important migratory routes and major spawning tributaries. Aerial tracking surveys were used to locate fish in spawning areas and between stations. The fish responded well to the capture and handling procedures, with most (2,790, 98%) resuming upriver movements. Although the fish initially displayed a negative tagging response, with slower migration rates observed immediately after release, the duration of this response was relatively short (several days) and less severe as the fish moved upriver. Independent measures indicated that the swimming speeds and timing of the fish upriver from the tagging area were comparable to untagged fish, suggesting that the tagging methods used were relatively benign. Fish returned to spawning areas throughout the basin, ranging from several hundred to over 3,000 km from the tagging area. Distribution patterns were similar across years, suggesting that the principal components of the run were identified. Most spawning fish were clustered in a number of key tributaries, with smaller numbers of fish located in other spatially isolated areas. The fish typically returned to clear water tributaries that were relatively entrenched, had moderate gradients, and were associated with upland areas. Fish were largely absent in lowland reaches characterized by meandering, low gradient, highly alluvial channels often associated with main river floodplains. There was suggestive evidence of mainstem spawning in reaches of the Upper Yukon. The status of fish remaining in other mainstem areas was less certain, and may represent local spawning activity or fish that died while in-transit to upriver areas. Although Chinook salmon spawned throughout the basin, the run was dominated by two regional components (Tanana and Upper Yukon), which annually comprised over 70% of the return. Substantially fewer fish returned to other areas ranging from 2-9% of the return, although the collective contribution of these stocks was appreciable. Most regional returns consisted of several principal stocks and a number of small, spatially isolated populations. Regional and stock composition estimates were similar across years even though differences in run abundance were reported, suggesting that these abundance differences were not related to regional or stock-specific differences. Run timing was relatively compressed compared to rivers in the southern portion of the range, with most stocks passing through the lower river over a 6-week period, ranging from 16 to 38 d. Run timing was generally earlier for stocks traveling farther upriver, although exceptions were noted. Lower basin stocks were primarily later run fish. Pronounced differences were observed in the migration rates (km/d) exhibited by regional stocks. Substantially slower swimming speeds were observed for fish returning to terminal tributaries in the lower basin ranging from 28-40 km/d compared to 52-62 km/d for upper basin stocks. The migratory patterns (migration rates in sequential reaches) of the fish also showed distinct regional differences. Average migration rates through the lower river were remarkably similar for the different stocks, ranging from 57-62 km/d, with most stocks exhibiting a general decline as the fish moved farther upriver. Tanana River stocks displayed a pronounced reduction in swimming speed after leaving the Yukon River main stem, with migration rates declining to 24 km/d on average as the fish approached their terminal tributaries. Conversely, upper basin stocks exhibited a relatively gradual (but variable) overall decline in migration rate even though these fish were traveling substantially greater distances upriver. Average migration rates for upper basin stocks ranged from 43-61 km/d as the fish approached their terminal tributaries. There was substantial variation in the migratory patterns exhibited by individual fish, although these patterns tended to be similar to the patterns exhibited by the regional stocks, particularly as the fish moved farther upriver from the tagging area. The dominant source of variation among fish reflected the average migration rate, with individual fish traveling slower in the lower basin exhibiting consistently slower migration rates as they moved upriver compared to their faster moving counterparts. This migratory pattern was consistent across stocks, and on average explained 74% of the within-stock variation in migration rate represented by the multivariate data. The second source of variation in migration rate reflected a shift in the relative swimming speeds of the individual fish as they progressed upriver. Although movement rates declined for nearly all of the fish during the migration, differences were observed in the pattern of the decline. Fish with faster migration rates in the lower river exhibited a pronounced decline in swimming speed as they moved upriver, whereas fish moving slower in the lower river displayed a more gradual decline in migration rate. On average, this migratory pattern explained 22% of the within-stock variation in migration rate represented by the multivariate data. Most fish (98%) exhibited continuous upriver movements and strong fidelity to the rivers they entered. However a small number of fish (n = 66) deviated from this pattern. Some of these individuals initially passed their final destination and continued upriver for varying distances before reversing direction, swimming back downstream, and entering their terminal tributary. Although most of these excursions were relatively short (< 30 km), there were several instances where fish traveled hundreds of kilometers out of their way. Thirty-four fish tracked to terminal tributaries subsequently left these rivers, and traveled to other terminal tributaries within the basin (n = 31) or were harvested in upriver fisheries (n = 3). Although most of these incidents involved nearby tributaries, major diversions were also observed, with several fish traveling over 300 km to natal rivers after leaving the initial tributary. Chinook salmon returns to the Yukon River typically consisted of a series of distinct and sizable increases in the number fish entering the river over the course of the run, commonly referred to as pulses. A large number of fish (n = 251) were radio tagged over a 4-day period during a pulse in 2003 to provide information on the progression of the pulse as it moved upriver. The time taken by the pulse to move past subsequent upriver locations increased as the fish moved farther upriver from the tagging area, with the fish passing sites located 580 and 800 km upriver over a span of 14 and 21 d, respectively. Although not surprising considering the extensive variation in migration rates observed among individual fish, this finding does suggest that these pulses do not represent cohesive aggregates of fish moving upriver. Unlike the well established methods used to estimate other life history characteristics, the development of quantitative methods for analyzing and modeling fish movements has lagged noticeably behind, due in part to the complexity associated with movement data and (prior to the advent of telemetry) the difficulty of collecting this type of information on free-ranging individuals. Two fundamentally different analytical approaches, hierarchical linear regression models and multivariate ordination, were used during this study to evaluate factors thought to influence the upriver movements of the fish. In spite of the inherent differences, both methods provided strikingly similar results, indicating that the study findings were not dependent on the approach used, and suggesting that the results were plausible based on the information available and the weight of evidence. Both analytical methods had advantages, and provided complementary information. With hierarchical linear models, it was possible to simultaneously evaluate a wide range of explanatory variables (in our case, both biological and environmental), which provided standardized comparisons and simplified the interpretation of the results. Since both fixed and random effects were incorporated in the models, it was possible to account for sources of variation when insufficient information was available to identify the underlining factors – an important consideration since few field studies provide comprehensive data. With multivariate ordination, separate analyzes were needed to examine the relationships between the migration rates and the biotic and physical variables. In addition to being cumbersome, this limitation made it more difficult to compare the relative influence of the different factors and interactions between factors. However, ordination was very useful as an exploratory tool. Although compartmentalized by stock, across fish comparisons were simple and relatively straightforward. Because the explanatory variables were evaluated separately in relation to the ordination score assigned to the fish, it was possible to examine and compare highly correlated variables. Ordination was also able to identify overall patterns within the data and assess the relative importance. While this can be accomplished within the framework of linear regression using mixture models to determine whether multiple distributions exist within the data, the process is much simpler with ordination. The migratory patterns of the fish were influenced by a wide range of factors, with evidentiary support for complex, multi-faceted relationships. Physical features of the basin demonstrated stronger explanatory power, accounting for over 70% of the observed variation in migration rate compared to 18% for the biological characteristics of the fish. Parameter estimates associated with the steepness of the migratory route and remaining distance the fish had to travel to reach their natal rivers were most strongly correlated with migration rate, with consistent relationships observed across stocks. Migration rates were also noticeably slower in extensively braided reaches of the basin. The weaker relationships between migration rate and biotic factors may reflect stabilizing selection on long-distance migrants. Smaller fish exhibited minimally faster swimming speeds on average than larger individuals. This relationship was stronger in highly braided reaches. Run timing was positively related to migration rate for most stocks. Surprisingly, upper basin stocks traveling farther upriver displayed progressively negative relationships, suggesting that late-run fish were moving slower. Ancillary information suggests that this decline may relate to deteriorating fish condition later in the season. Title: Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin Author: Eiler, John H. Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has raised concerns over the future status of the returns, and severely impacted commercial and subsistence fisheries within the drainage. Management is further complicated by the mixed-stock composition of the run, the presence of other temporally similar salmon species, and the need to equitably allocate harvests between the numerous fisheries and user groups scattered throughout the basin. Detailed information is needed on Chinook salmon run characteristics to better understand and manage the returns, and facilitate conservation efforts. However, this goal is exacerbated by the massive size and remote nature of the basin, the large number of highly mobile fish, and the compressed timing of the run. To address these challenges, radio telemetry was used to determine the stock composition and spawning distribution of the returns, and the migratory characteristics of the fish. The migratory patterns exhibited by returning salmon provide a number of insights into the status of the run. Since the Yukon River is essentially free-flowing (i.e., not regulated), this study also presented an opportunity to document the distribution and upriver movements of large returns of wild Chinook salmon under natural conditions. During 2002-2004, returning adult Chinook salmon were captured in the lower Yukon River (approximately 300 km upriver from the river mouth), tagged with radio transmitters, and tracked upriver using remote tracking stations located on important migratory routes and major spawning tributaries. Aerial tracking surveys were used to locate fish in spawning areas and between stations. The fish responded well to the capture and handling procedures, with most (2,790, 98%) resuming upriver movements. Although the fish initially displayed a negative tagging response, with slower migration rates observed immediately after release, the duration of this response was relatively short (several days) and less severe as the fish moved upriver. Independent measures indicated that the swimming speeds and timing of the fish upriver from the tagging area were comparable to untagged fish, suggesting that the tagging methods used were relatively benign. Fish returned to spawning areas throughout the basin, ranging from several hundred to over 3,000 km from the tagging area. Distribution patterns were similar across years, suggesting that the principal components of the run were identified. Most spawning fish were clustered in a number of key tributaries, with smaller numbers of fish located in other spatially isolated areas. The fish typically returned to clear water tributaries that were relatively entrenched, had moderate gradients, and were associated with upland areas. Fish were largely absent in lowland reaches characterized by meandering, low gradient, highly alluvial channels often associated with main river floodplains. There was suggestive evidence of mainstem spawning in reaches of the Upper Yukon. The status of fish remaining in other mainstem areas was less certain, and may represent local spawning activity or fish that died while in-transit to upriver areas. Although Chinook salmon spawned throughout the basin, the run was dominated by two regional components (Tanana and Upper Yukon), which annually comprised over 70% of the return. Substantially fewer fish returned to other areas ranging from 2-9% of the return, although the collective contribution of these stocks was appreciable. Most regional returns consisted of several principal stocks and a number of small, spatially isolated populations. Regional and stock composition estimates were similar across years even though differences in run abundance were reported, suggesting that these abundance differences were not related to regional or stock-specific differences. Run timing was relatively compressed compared to rivers in the southern portion of the range, with most stocks passing through the lower river over a 6-week period, ranging from 16 to 38 d. Run timing was generally earlier for stocks traveling farther upriver, although exceptions were noted. Lower basin stocks were primarily later run fish. Pronounced differences were observed in the migration rates (km/d) exhibited by regional stocks. Substantially slower swimming speeds were observed for fish returning to terminal tributaries in the lower basin ranging from 28-40 km/d compared to 52-62 km/d for upper basin stocks. The migratory patterns (migration rates in sequential reaches) of the fish also showed distinct regional differences. Average migration rates through the lower river were remarkably similar for the different stocks, ranging from 57-62 km/d, with most stocks exhibiting a general decline as the fish moved farther upriver. Tanana River stocks displayed a pronounced reduction in swimming speed after leaving the Yukon River main stem, with migration rates declining to 24 km/d on average as the fish approached their terminal tributaries. Conversely, upper basin stocks exhibited a relatively gradual (but variable) overall decline in migration rate even though these fish were traveling substantially greater distances upriver. Average migration rates for upper basin stocks ranged from 43-61 km/d as the fish approached their terminal tributaries. There was substantial variation in the migratory patterns exhibited by individual fish, although these patterns tended to be similar to the patterns exhibited by the regional stocks, particularly as the fish moved farther upriver from the tagging area. The dominant source of variation among fish reflected the average migration rate, with individual fish traveling slower in the lower basin exhibiting consistently slower migration rates as they moved upriver compared to their faster moving counterparts. This migratory pattern was consistent across stocks, and on average explained 74% of the within-stock variation in migration rate represented by the multivariate data. The second source of variation in migration rate reflected a shift in the relative swimming speeds of the individual fish as they progressed upriver. Although movement rates declined for nearly all of the fish during the migration, differences were observed in the pattern of the decline. Fish with faster migration rates in the lower river exhibited a pronounced decline in swimming speed as they moved upriver, whereas fish moving slower in the lower river displayed a more gradual decline in migration rate. On average, this migratory pattern explained 22% of the within-stock variation in migration rate represented by the multivariate data. Most fish (98%) exhibited continuous upriver movements and strong fidelity to the rivers they entered. However a small number of fish (n = 66) deviated from this pattern. Some of these individuals initially passed their final destination and continued upriver for varying distances before reversing direction, swimming back downstream, and entering their terminal tributary. Although most of these excursions were relatively short (< 30 km), there were several instances where fish traveled hundreds of kilometers out of their way. Thirty-four fish tracked to terminal tributaries subsequently left these rivers, and traveled to other terminal tributaries within the basin (n = 31) or were harvested in upriver fisheries (n = 3). Although most of these incidents involved nearby tributaries, major diversions were also observed, with several fish traveling over 300 km to natal rivers after leaving the initial tributary. Chinook salmon returns to the Yukon River typically consisted of a series of distinct and sizable increases in the number fish entering the river over the course of the run, commonly referred to as pulses. A large number of fish (n = 251) were radio tagged over a 4-day period during a pulse in 2003 to provide information on the progression of the pulse as it moved upriver. The time taken by the pulse to move past subsequent upriver locations increased as the fish moved farther upriver from the tagging area, with the fish passing sites located 580 and 800 km upriver over a span of 14 and 21 d, respectively. Although not surprising considering the extensive variation in migration rates observed among individual fish, this finding does suggest that these pulses do not represent cohesive aggregates of fish moving upriver. Unlike the well established methods used to estimate other life history characteristics, the development of quantitative methods for analyzing and modeling fish movements has lagged noticeably behind, due in part to the complexity associated with movement data and (prior to the advent of telemetry) the difficulty of collecting this type of information on free-ranging individuals. Two fundamentally different analytical approaches, hierarchical linear regression models and multivariate ordination, were used during this study to evaluate factors thought to influence the upriver movements of the fish. In spite of the inherent differences, both methods provided strikingly similar results, indicating that the study findings were not dependent on the approach used, and suggesting that the results were plausible based on the information available and the weight of evidence. Both analytical methods had advantages, and provided complementary information. With hierarchical linear models, it was possible to simultaneously evaluate a wide range of explanatory variables (in our case, both biological and environmental), which provided standardized comparisons and simplified the interpretation of the results. Since both fixed and random effects were incorporated in the models, it was possible to account for sources of variation when insufficient information was available to identify the underlining factors – an important consideration since few field studies provide comprehensive data. With multivariate ordination, separate analyzes were needed to examine the relationships between the migration rates and the biotic and physical variables. In addition to being cumbersome, this limitation made it more difficult to compare the relative influence of the different factors and interactions between factors. However, ordination was very useful as an exploratory tool. Although compartmentalized by stock, across fish comparisons were simple and relatively straightforward. Because the explanatory variables were evaluated separately in relation to the ordination score assigned to the fish, it was possible to examine and compare highly correlated variables. Ordination was also able to identify overall patterns within the data and assess the relative importance. While this can be accomplished within the framework of linear regression using mixture models to determine whether multiple distributions exist within the data, the process is much simpler with ordination. The migratory patterns of the fish were influenced by a wide range of factors, with evidentiary support for complex, multi-faceted relationships. Physical features of the basin demonstrated stronger explanatory power, accounting for over 70% of the observed variation in migration rate compared to 18% for the biological characteristics of the fish. Parameter estimates associated with the steepness of the migratory route and remaining distance the fish had to travel to reach their natal rivers were most strongly correlated with migration rate, with consistent relationships observed across stocks. Migration rates were also noticeably slower in extensively braided reaches of the basin. The weaker relationships between migration rate and biotic factors may reflect stabilizing selection on long-distance migrants. Smaller fish exhibited minimally faster swimming speeds on average than larger individuals. This relationship was stronger in highly braided reaches. Run timing was positively related to migration rate for most stocks. Surprisingly, upper basin stocks traveling farther upriver displayed progressively negative relationships, suggesting that late-run fish were moving slower. Ancillary information suggests that this decline may relate to deteriorating fish condition later in the season. Close