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• 2341. [Article] Application of transport-reaction modeling to constrain biogeochemical processes in marine sediments

  Quantifying the mass transport through marine sediments, and the geochemical response to such flow with numerical models has become a common and powerful approach for geochemical data interpretation. In ...

  Citation × Citation Citation Abstract Copy Title: Application of transport-reaction modeling to constrain biogeochemical processes in marine sediments Author: Hong, Wei-Li Quantifying the mass transport through marine sediments, and the geochemical response to such flow with numerical models has become a common and powerful approach for geochemical data interpretation. In this dissertation, I developed and applied transport-reaction models to unravel complex and interdependent reactions involving carbon, sulfur and silica transformations in shallow marine sediments, and the impact of physical (mass transport deposits) and depositional events (volcanic ash input) on the overall geochemical state of the system. Carbon cycling in the gas hydrate bearing sediments of the Ulleung Basin was quantified using both box and kinetic modeling approaches. The box model balances mass, flux, and carbon isotopes of carbon (Chapter 2), and led to a better understanding of how methane is cycled in the marine sediments of this area. This effort demonstrates the significance of CO₂ reduction, a previously overlooked reaction. The picture of reaction network derived from this work serves as the foundation for a transport-reaction model (Chapter 3). The kinetic model results revealed a very different biogeochemistry between two distinct fluid-flow environments. At sites where transport is predominantly diffusive (non-chimney environments), organic matter decomposition is the dominant process driving production of methane, dissolved inorganic carbon (DIC) and consumption of sulfate. In contrast, anaerobic oxidation of methane (AOM) drives both carbon and sulfur cycles in the advective settings characterized by acoustic chimneys indicative of gas transport. I show that methane produced within the model domain, through CO₂ reduction and methanogenesis, fuels AOM in the non-chimney sites while AOM is primarily induced by methane from external sources at the chimney sites. A simulation of the system evolution from a non-chimney to a chimney condition was developed by increasing the bottom methane supply to an originally diffusion-controlled site. Results from this exercise show that the higher methane flux leads to a higher AOM activity, and enhanced organic matter decomposition through methanogenesis. Organic carbon cycling is also affected by changes in the depositional environment, as shown by application of the kinetic model to the sediments from the Krishna-Godavary (K-G) basin along the eastern Indian margin (Chapter 4). Proximity to large rivers results in the widespread occurrence of mass transport deposits (MTD) throughout the basin. In this work, MTD is defined as a fluidized sediment block whose pore water composition is identical to sea water value to reflect the homogenization process during sediment transport. The pore water sulfate and ammonium profiles measured at seven sites drilled in the K-G Basin during the NGHP-01 expedition were simulated to provide a quantitative description of how MTDs can affect geochemistry profiles, not only for sulfate and ammonium but potentially all pore water species. This model provides reliable estimates of the MTDs thickness, the time elapsed after the most recent event, and the organoclastic sulfate reduction rate at these seven sites. A transport-reaction modeling approach was also applied to investigate the silica diagenetic reactions fueled by volcanic ash decomposition in Shikuko Basin, Nankai Trough (Chapter 5). The model developed for this setting reproduces a silica diagenetic boundary (SDB) at each site, which is defined by marked decreases in reactive volcanic ash, pore water silica and potassium. Volcanic ash alteration was constrained by modeling pore water ⁸⁷Sr/⁸⁶Sr profiles. Below the SDB, formation of clinoptilolite consumes potassium and regulates the extension of amorphous silica by consuming SiO₂(aq). The observed low SiO₂(aq) and dissolved potassium in these deep sequences require continuous precipitation of clinoptilolite; however in order to maintain oversaturation of this mineral at the low SiO₂(aq) in sediments below the SDB, an increase in pH is required, consistent with pore water observations. Thermal history, rather than temperature alone, controls the inferred reaction network as shown by the convergence of the thermal maturity of sediments at the SDB from all studied sites and is consistent with other locations documented onshore Japan. These results are valuable as we move forward in understanding the mechanisms and consequences of ash alteration in convergent margins worldwide. Title: Application of transport-reaction modeling to constrain biogeochemical processes in marine sediments Author: Hong, Wei-Li Quantifying the mass transport through marine sediments, and the geochemical response to such flow with numerical models has become a common and powerful approach for geochemical data interpretation. In this dissertation, I developed and applied transport-reaction models to unravel complex and interdependent reactions involving carbon, sulfur and silica transformations in shallow marine sediments, and the impact of physical (mass transport deposits) and depositional events (volcanic ash input) on the overall geochemical state of the system. Carbon cycling in the gas hydrate bearing sediments of the Ulleung Basin was quantified using both box and kinetic modeling approaches. The box model balances mass, flux, and carbon isotopes of carbon (Chapter 2), and led to a better understanding of how methane is cycled in the marine sediments of this area. This effort demonstrates the significance of CO₂ reduction, a previously overlooked reaction. The picture of reaction network derived from this work serves as the foundation for a transport-reaction model (Chapter 3). The kinetic model results revealed a very different biogeochemistry between two distinct fluid-flow environments. At sites where transport is predominantly diffusive (non-chimney environments), organic matter decomposition is the dominant process driving production of methane, dissolved inorganic carbon (DIC) and consumption of sulfate. In contrast, anaerobic oxidation of methane (AOM) drives both carbon and sulfur cycles in the advective settings characterized by acoustic chimneys indicative of gas transport. I show that methane produced within the model domain, through CO₂ reduction and methanogenesis, fuels AOM in the non-chimney sites while AOM is primarily induced by methane from external sources at the chimney sites. A simulation of the system evolution from a non-chimney to a chimney condition was developed by increasing the bottom methane supply to an originally diffusion-controlled site. Results from this exercise show that the higher methane flux leads to a higher AOM activity, and enhanced organic matter decomposition through methanogenesis. Organic carbon cycling is also affected by changes in the depositional environment, as shown by application of the kinetic model to the sediments from the Krishna-Godavary (K-G) basin along the eastern Indian margin (Chapter 4). Proximity to large rivers results in the widespread occurrence of mass transport deposits (MTD) throughout the basin. In this work, MTD is defined as a fluidized sediment block whose pore water composition is identical to sea water value to reflect the homogenization process during sediment transport. The pore water sulfate and ammonium profiles measured at seven sites drilled in the K-G Basin during the NGHP-01 expedition were simulated to provide a quantitative description of how MTDs can affect geochemistry profiles, not only for sulfate and ammonium but potentially all pore water species. This model provides reliable estimates of the MTDs thickness, the time elapsed after the most recent event, and the organoclastic sulfate reduction rate at these seven sites. A transport-reaction modeling approach was also applied to investigate the silica diagenetic reactions fueled by volcanic ash decomposition in Shikuko Basin, Nankai Trough (Chapter 5). The model developed for this setting reproduces a silica diagenetic boundary (SDB) at each site, which is defined by marked decreases in reactive volcanic ash, pore water silica and potassium. Volcanic ash alteration was constrained by modeling pore water ⁸⁷Sr/⁸⁶Sr profiles. Below the SDB, formation of clinoptilolite consumes potassium and regulates the extension of amorphous silica by consuming SiO₂(aq). The observed low SiO₂(aq) and dissolved potassium in these deep sequences require continuous precipitation of clinoptilolite; however in order to maintain oversaturation of this mineral at the low SiO₂(aq) in sediments below the SDB, an increase in pH is required, consistent with pore water observations. Thermal history, rather than temperature alone, controls the inferred reaction network as shown by the convergence of the thermal maturity of sediments at the SDB from all studied sites and is consistent with other locations documented onshore Japan. These results are valuable as we move forward in understanding the mechanisms and consequences of ash alteration in convergent margins worldwide. Close

• 2342. [Article] The impact of Oregon’s Coordinated Care Organizations on Prenatal Care Access and Quality : A Difference-in-Differences Analysis

  Background: Prenatal care (PNC) is an important preventive health service that can influence the health of the four million women who give birth annually in the United States, and the health their infants. ...

  Citation × Citation Citation Abstract Copy Title: The impact of Oregon’s Coordinated Care Organizations on Prenatal Care Access and Quality : A Difference-in-Differences Analysis Author: Muoto, Ifeoma O. Background: Prenatal care (PNC) is an important preventive health service that can influence the health of the four million women who give birth annually in the United States, and the health their infants. Despite efforts to increase women’s access to PNC services, significant disparities in PNC utilization and maternal/child health outcomes by insurance type and race/ethnicity persist in the United States. The past decade has witnessed several major health reforms at both national and state levels. However, the impact of these reforms on the quality of PNC, and on disparities in PNC utilization is not known. In 2012, the state of Oregon established Coordinated Care Organizations (CCOs) as comprehensive providers of care for Oregon’s Medicaid beneficiaries. CCOs are characterized by a global budget payment mechanism and financial incentives for high quality care. Timely initiation of PNC – which has been associated with improved maternal and infant health and utilization outcomes – is one of seventeen quality metrics for which CCOs can receive incentive payments. Objectives: The first objective of the current study was to estimate the impact of CCO implementation on the probability of initiating PNC in the first trimester, and on PNC adequacy among Oregon Medicaid beneficiaries. The second objective of the study was to determine if the implementation of CCOs influenced disparities in PNC utilization between Medicaid and privately-insured women, and between non-Hispanic White women and Hispanic/non-Hispanic Black women. Study Design: This quasi-experimental retrospective observational study drew from two data sources: Oregon Vital Records (Birth Certificate statistical files) from the department of Health Analytics of the Oregon state public health department and Washington State’s Linked Birth- CHARS (Comprehensive Hospital Abstract Reporting System) data from the Washington State department of health. A difference-in-differences approach examined PNC utilization before and after CCO implementation. Washington State served as the control group, as its Medicaid financing and delivery systems remained unchanged. Multivariable linear probability analysis was used to control for confounding factors, including maternal age, race/ethnicity, education, parity, marital status, smoking history, previous preterm birth, and maternal morbidity. Population Studied: All births in Oregon and Washington from 2008 – 2013, which were covered by either Medicaid or private insurance, were included in the analysis. Since CCOs started operating mid-year in 2012, June through December 2012 was considered a transition period and births during this period were excluded from the analysis. Principal Findings: CCO implementation was associated with a significant increase in the probability of PNC initiation in the first trimester and a reduction in insurance-type disparities in first trimester PNC initiation and PNC adequacy among Oregon Medicaid beneficiaries. Racial/ethnic disparities did not change following CCO implementation. Conclusions: The implementation of CCOs in Oregon had a positive impact on the timeliness of PNC initiation among Medicaid beneficiaries, and also reduced disparities in PNC quality between Medicaid and privately-insured women. Implications for Policy or Practice: The ongoing health system transformation in Oregon provides an ideal setting to assess the impact of a novel health service delivery model on PNC utilization. If Oregon is successful in this bold and unprecedented move, it could serve as a model for other Medicaid and commercial health plans seeking to improve PNC quality. Further study on the longer-term effects of CCO implementation on PNC quality as well as the effect of CCOs on other health care domains, is warranted. Title: The impact of Oregon’s Coordinated Care Organizations on Prenatal Care Access and Quality : A Difference-in-Differences Analysis Author: Muoto, Ifeoma O. Background: Prenatal care (PNC) is an important preventive health service that can influence the health of the four million women who give birth annually in the United States, and the health their infants. Despite efforts to increase women’s access to PNC services, significant disparities in PNC utilization and maternal/child health outcomes by insurance type and race/ethnicity persist in the United States. The past decade has witnessed several major health reforms at both national and state levels. However, the impact of these reforms on the quality of PNC, and on disparities in PNC utilization is not known. In 2012, the state of Oregon established Coordinated Care Organizations (CCOs) as comprehensive providers of care for Oregon’s Medicaid beneficiaries. CCOs are characterized by a global budget payment mechanism and financial incentives for high quality care. Timely initiation of PNC – which has been associated with improved maternal and infant health and utilization outcomes – is one of seventeen quality metrics for which CCOs can receive incentive payments. Objectives: The first objective of the current study was to estimate the impact of CCO implementation on the probability of initiating PNC in the first trimester, and on PNC adequacy among Oregon Medicaid beneficiaries. The second objective of the study was to determine if the implementation of CCOs influenced disparities in PNC utilization between Medicaid and privately-insured women, and between non-Hispanic White women and Hispanic/non-Hispanic Black women. Study Design: This quasi-experimental retrospective observational study drew from two data sources: Oregon Vital Records (Birth Certificate statistical files) from the department of Health Analytics of the Oregon state public health department and Washington State’s Linked Birth- CHARS (Comprehensive Hospital Abstract Reporting System) data from the Washington State department of health. A difference-in-differences approach examined PNC utilization before and after CCO implementation. Washington State served as the control group, as its Medicaid financing and delivery systems remained unchanged. Multivariable linear probability analysis was used to control for confounding factors, including maternal age, race/ethnicity, education, parity, marital status, smoking history, previous preterm birth, and maternal morbidity. Population Studied: All births in Oregon and Washington from 2008 – 2013, which were covered by either Medicaid or private insurance, were included in the analysis. Since CCOs started operating mid-year in 2012, June through December 2012 was considered a transition period and births during this period were excluded from the analysis. Principal Findings: CCO implementation was associated with a significant increase in the probability of PNC initiation in the first trimester and a reduction in insurance-type disparities in first trimester PNC initiation and PNC adequacy among Oregon Medicaid beneficiaries. Racial/ethnic disparities did not change following CCO implementation. Conclusions: The implementation of CCOs in Oregon had a positive impact on the timeliness of PNC initiation among Medicaid beneficiaries, and also reduced disparities in PNC quality between Medicaid and privately-insured women. Implications for Policy or Practice: The ongoing health system transformation in Oregon provides an ideal setting to assess the impact of a novel health service delivery model on PNC utilization. If Oregon is successful in this bold and unprecedented move, it could serve as a model for other Medicaid and commercial health plans seeking to improve PNC quality. Further study on the longer-term effects of CCO implementation on PNC quality as well as the effect of CCOs on other health care domains, is warranted. Close

• 2343. [Article] Converting forest biomass to energy in Oregon : stakeholder perspectives on a growing movement

  Within Oregon there is considerable interest in the possibility of converting woody biomass to energy. This interest stems from three converging factors: the desire to reduce the threat of uncharacteristic ...

  Citation × Citation Citation Abstract Copy Title: Converting forest biomass to energy in Oregon : stakeholder perspectives on a growing movement Author: Stidham, Melanie Within Oregon there is considerable interest in the possibility of converting woody biomass to energy. This interest stems from three converging factors: the desire to reduce the threat of uncharacteristic wildfire by removing excess material from the forests, the possibility to stimulate rural economies that are dependent on forest products, and generation of renewable and/or clean energy from a local source. There have been a number of studies to assess the feasibility of wide-scale conversion of biomass to energy. These efforts have largely focused on technical barriers to the use of biomass for energy rather than social barriers. This study explores the social context of converting forest biomass to energy, through use of semi-structured interviews. Forty interviewees were purposively selected from the following Oregon stakeholder groups: federal and state agencies, elected officials, community organizations, conservation organizations, the forest industry sector, Tribes, energy utilities and non-utility energy experts. Information gained through the interviews was used to meet two research objectives: 1) to understand stakeholders' views on converting forest biomass to energy in Oregon; 2) to identify, from the perspectives of stakeholders, the opportunities for and barriers to converting forest biomass to energy, and potential strategies to overcome the barriers. In addition, there were two secondary objectives: a) to identify areas of common ground and conflict between and within stakeholder groups; and b) to identify policy components that would be necessary in the integration of the forestry and energy industries in Oregon. Among research participants there was wide agreement on what constitutes forest biomass; typically small diameter material that is currently non-merchantable, produced as a by-product of restoration or other forest management activities. There was most agreement that restoration treatments are needed in low-elevation ponderosa pine forests in eastern and southwestern Oregon to reduce the risk of uncharacteristically large and severe wildfire. It is this risk of unusually intense wildfire that many research participants felt was driving this issue in Oregon, rather than potential energy or rural economic development benefits. Many research participants wanted at-risk forests restored to conditions within their historic/natural range of variability, which depended on site specific characteristics, but generally meant fewer trees per acre and inclusion of low-intensity fire. The top three reasons research participants were interested in biomass utilization were the opportunities to generate renewable energy, restore forests, and stimulate economic growth in rural communities. While participants were enthusiastic about these opportunities, they brought up a number of barriers that would have to be addressed before the full suite of opportunities could be realized. The most vital and most challenging barrier was access to supply. Factors making supply more difficult to secure included the expense associated with long transport distances, and that while supply needs to be long-term, continuous, inexpensive, and guaranteed, it is mostly on federal land, where the public is involved in land management decisions and politics plays a role. Another challenge is the long history of contention between parties related to forest products coming from federal land, and these parties would have to all agree that biomass utilization using supply from federal forests is acceptable before supply could be made available. Many research participants suggested that collaboration could allow these projects to be developed in a manner acceptable to all parties. Costs could be federally subsidized to make projects more feasible. Participants encouraged development of pilot projects to move discussion from speculation to actuality. Many research participants expressed more comfort in smaller energy facilities to prevent energy needs from dictating forest management, i.e., to prevent the tail from wagging the dog. The overarching goal of this research is to provide information useful to collaboration groups, policymakers, land managers, communities, and relevant advocacy groups to create a foundation for discussions as forest biomass energy becomes an increasingly prominent issue in Oregon. Title: Converting forest biomass to energy in Oregon : stakeholder perspectives on a growing movement Author: Stidham, Melanie Within Oregon there is considerable interest in the possibility of converting woody biomass to energy. This interest stems from three converging factors: the desire to reduce the threat of uncharacteristic wildfire by removing excess material from the forests, the possibility to stimulate rural economies that are dependent on forest products, and generation of renewable and/or clean energy from a local source. There have been a number of studies to assess the feasibility of wide-scale conversion of biomass to energy. These efforts have largely focused on technical barriers to the use of biomass for energy rather than social barriers. This study explores the social context of converting forest biomass to energy, through use of semi-structured interviews. Forty interviewees were purposively selected from the following Oregon stakeholder groups: federal and state agencies, elected officials, community organizations, conservation organizations, the forest industry sector, Tribes, energy utilities and non-utility energy experts. Information gained through the interviews was used to meet two research objectives: 1) to understand stakeholders' views on converting forest biomass to energy in Oregon; 2) to identify, from the perspectives of stakeholders, the opportunities for and barriers to converting forest biomass to energy, and potential strategies to overcome the barriers. In addition, there were two secondary objectives: a) to identify areas of common ground and conflict between and within stakeholder groups; and b) to identify policy components that would be necessary in the integration of the forestry and energy industries in Oregon. Among research participants there was wide agreement on what constitutes forest biomass; typically small diameter material that is currently non-merchantable, produced as a by-product of restoration or other forest management activities. There was most agreement that restoration treatments are needed in low-elevation ponderosa pine forests in eastern and southwestern Oregon to reduce the risk of uncharacteristically large and severe wildfire. It is this risk of unusually intense wildfire that many research participants felt was driving this issue in Oregon, rather than potential energy or rural economic development benefits. Many research participants wanted at-risk forests restored to conditions within their historic/natural range of variability, which depended on site specific characteristics, but generally meant fewer trees per acre and inclusion of low-intensity fire. The top three reasons research participants were interested in biomass utilization were the opportunities to generate renewable energy, restore forests, and stimulate economic growth in rural communities. While participants were enthusiastic about these opportunities, they brought up a number of barriers that would have to be addressed before the full suite of opportunities could be realized. The most vital and most challenging barrier was access to supply. Factors making supply more difficult to secure included the expense associated with long transport distances, and that while supply needs to be long-term, continuous, inexpensive, and guaranteed, it is mostly on federal land, where the public is involved in land management decisions and politics plays a role. Another challenge is the long history of contention between parties related to forest products coming from federal land, and these parties would have to all agree that biomass utilization using supply from federal forests is acceptable before supply could be made available. Many research participants suggested that collaboration could allow these projects to be developed in a manner acceptable to all parties. Costs could be federally subsidized to make projects more feasible. Participants encouraged development of pilot projects to move discussion from speculation to actuality. Many research participants expressed more comfort in smaller energy facilities to prevent energy needs from dictating forest management, i.e., to prevent the tail from wagging the dog. The overarching goal of this research is to provide information useful to collaboration groups, policymakers, land managers, communities, and relevant advocacy groups to create a foundation for discussions as forest biomass energy becomes an increasingly prominent issue in Oregon. Close

• 2344. [Article] Carbon dynamics following landscape fire: influence of burn severity, climate, and stand history in the Metolius Watershed, Oregon

  Fire is a fundamental disturbance that drives terrestrial and atmospheric carbon dynamics. Previous studies have quantified fire effects on carbon cycling from local to global scales but have focused ...

  Citation × Citation Citation Abstract Copy Title: Carbon dynamics following landscape fire: influence of burn severity, climate, and stand history in the Metolius Watershed, Oregon Author: Meigs, Garrett W. Fire is a fundamental disturbance that drives terrestrial and atmospheric carbon dynamics. Previous studies have quantified fire effects on carbon cycling from local to global scales but have focused nearly exclusively on high-severity, stand-replacement fire. Since 2002, variable-severity wildfires have burned more than 65 000 ha across the east slope of the Oregon Cascades, including 4 large fires that burned ca. 50% of the forested area within the Metolius Watershed in 2002 and 2003. This thesis integrates data from 64 field plots, remote-sensing, and an ecosystem process model to investigate the effects of low-, moderate-, and high-severity fire. The primary research objectives were to: (a) quantify combustion and mortality effects on carbon pools, postfire net ecosystem production (NEP), and potential regeneration trajectories at the stand scale; (b) introduce novel remote-sensing datasets into a modeling framework to assess the importance of low- and moderate-severity fire across the landscape and region. At the stand-scale, the 3 levels of burn severity (overstory tree mortality) resulted in profoundly different impacts on combustion, mortality, postfire carbon balance, and potential regeneration trajectories. Simulated combustion ranged from 16.6 to 32.3 Mg C ha-1, or 13% to 35% of prefire aboveground carbon. C transfers from fire-induced tree mortality were larger in magnitude than combustion, as live aboveground C decreased by >90% from low- to high-severity stands. Despite this decline, total net primary productivity (NPP) was only 40% lower in high- vs. low-severity stands, reflecting a compensatory effect of non-tree NPP. Dead wood respiratory losses were small relative to C uptake (range: 10-35% of total NPP), suggesting important decomposition lags in this seasonally-arid system. Although soil C, soil respiration, and fine root NPP were conserved across severity classes, NEP declined with increasing severity, driven by trends in aboveground NPP. Postfire conifer seedling density was generally abundant and varied over 5 orders of magnitude (study-wide median: 812, range: 0 – 62 134 seedlings ha-1). Seedling density was negatively correlated with overstory mortality, whereas shrub biomass showed the opposite response, indicating a wide range of potential successional trajectories. Despite substantial combustion and mortality effects on carbon pools and fluxes, the rapid response of postfire vegetation, coupled with conservation of belowground processes, may offset long-term declines in carbon storage, indicating a surprising degree of postfire stability. These stand-scale results describe a broad range of fire effects—a high degree of pyrodiversity—but because burn severity was not evenly distributed across space, the landscape-level fire effects depend on the severity mosaic. At the landscape-scale, moderate- and low-severity fire contributed 25% and 11% of total estimated pyrogenic carbon emission, respectively (0.66 Tg C total, or ca. 2.2% of statewide anthropogenic CO2 emissions equivalent from the same 2-year period). Moderate- and low-severity fire accounted for 23% and 5% of landscape-level tree mortality, respectively, which resulted in the transfer of 2.00 Tg C from live to dead pools. This carbon transfer was ca. 3-fold higher than the one-time pulse from pyrogenic emission, but it will likely take decades for this dead wood to decompose via heterotrophic respiration. The inclusion of moderate-severity fire reduced postfire (2004) mean annual NEP by 39% compared to the high-severity only scenario; low-severity fire influence on NEP was small (additional reduction of 11% in mean NEP), likely because of high tree survivorship and the relatively lower areal coverage of low-severity fire. One year postfire, burned areas were a strong C source (net C exchange across 53 000 ha: -0.065 Tg C y-1; mean ± SD: -123 ± 110 g C m-2 y-1) vs. a prefire mean near C neutral (1997-2001 mean NEP ± SD: -5 ± 51 g C m-2 y-1). The model has been known to underestimate carbon uptake in mature and old semi-arid forests, so the prefire value is likely underestimated. Despite the resurgence of wildfire across western North America, including a substantial increase in the proportion of high-severity fire in the ecoregions studied here, low- and moderate-severity wildfire accounts for the majority of burned area in the Pacific Northwest region. This non-stand-replacement fire has important consequences for carbon loss and uptake at landscape- and regional-scales. The results from this thesis suggest that by accounting for the full gradient of fire effects, carbon modelers can substantially reduce uncertainties in key components of regional and global carbon budgets, particularly pyrogenic emissions, mortality, and NEP. Understanding the effects of disturbance variability on terrestrial carbon cycling will become increasingly important in the context of emerging regional and global carbon policies. Title: Carbon dynamics following landscape fire: influence of burn severity, climate, and stand history in the Metolius Watershed, Oregon Author: Meigs, Garrett W. Fire is a fundamental disturbance that drives terrestrial and atmospheric carbon dynamics. Previous studies have quantified fire effects on carbon cycling from local to global scales but have focused nearly exclusively on high-severity, stand-replacement fire. Since 2002, variable-severity wildfires have burned more than 65 000 ha across the east slope of the Oregon Cascades, including 4 large fires that burned ca. 50% of the forested area within the Metolius Watershed in 2002 and 2003. This thesis integrates data from 64 field plots, remote-sensing, and an ecosystem process model to investigate the effects of low-, moderate-, and high-severity fire. The primary research objectives were to: (a) quantify combustion and mortality effects on carbon pools, postfire net ecosystem production (NEP), and potential regeneration trajectories at the stand scale; (b) introduce novel remote-sensing datasets into a modeling framework to assess the importance of low- and moderate-severity fire across the landscape and region. At the stand-scale, the 3 levels of burn severity (overstory tree mortality) resulted in profoundly different impacts on combustion, mortality, postfire carbon balance, and potential regeneration trajectories. Simulated combustion ranged from 16.6 to 32.3 Mg C ha-1, or 13% to 35% of prefire aboveground carbon. C transfers from fire-induced tree mortality were larger in magnitude than combustion, as live aboveground C decreased by >90% from low- to high-severity stands. Despite this decline, total net primary productivity (NPP) was only 40% lower in high- vs. low-severity stands, reflecting a compensatory effect of non-tree NPP. Dead wood respiratory losses were small relative to C uptake (range: 10-35% of total NPP), suggesting important decomposition lags in this seasonally-arid system. Although soil C, soil respiration, and fine root NPP were conserved across severity classes, NEP declined with increasing severity, driven by trends in aboveground NPP. Postfire conifer seedling density was generally abundant and varied over 5 orders of magnitude (study-wide median: 812, range: 0 – 62 134 seedlings ha-1). Seedling density was negatively correlated with overstory mortality, whereas shrub biomass showed the opposite response, indicating a wide range of potential successional trajectories. Despite substantial combustion and mortality effects on carbon pools and fluxes, the rapid response of postfire vegetation, coupled with conservation of belowground processes, may offset long-term declines in carbon storage, indicating a surprising degree of postfire stability. These stand-scale results describe a broad range of fire effects—a high degree of pyrodiversity—but because burn severity was not evenly distributed across space, the landscape-level fire effects depend on the severity mosaic. At the landscape-scale, moderate- and low-severity fire contributed 25% and 11% of total estimated pyrogenic carbon emission, respectively (0.66 Tg C total, or ca. 2.2% of statewide anthropogenic CO2 emissions equivalent from the same 2-year period). Moderate- and low-severity fire accounted for 23% and 5% of landscape-level tree mortality, respectively, which resulted in the transfer of 2.00 Tg C from live to dead pools. This carbon transfer was ca. 3-fold higher than the one-time pulse from pyrogenic emission, but it will likely take decades for this dead wood to decompose via heterotrophic respiration. The inclusion of moderate-severity fire reduced postfire (2004) mean annual NEP by 39% compared to the high-severity only scenario; low-severity fire influence on NEP was small (additional reduction of 11% in mean NEP), likely because of high tree survivorship and the relatively lower areal coverage of low-severity fire. One year postfire, burned areas were a strong C source (net C exchange across 53 000 ha: -0.065 Tg C y-1; mean ± SD: -123 ± 110 g C m-2 y-1) vs. a prefire mean near C neutral (1997-2001 mean NEP ± SD: -5 ± 51 g C m-2 y-1). The model has been known to underestimate carbon uptake in mature and old semi-arid forests, so the prefire value is likely underestimated. Despite the resurgence of wildfire across western North America, including a substantial increase in the proportion of high-severity fire in the ecoregions studied here, low- and moderate-severity wildfire accounts for the majority of burned area in the Pacific Northwest region. This non-stand-replacement fire has important consequences for carbon loss and uptake at landscape- and regional-scales. The results from this thesis suggest that by accounting for the full gradient of fire effects, carbon modelers can substantially reduce uncertainties in key components of regional and global carbon budgets, particularly pyrogenic emissions, mortality, and NEP. Understanding the effects of disturbance variability on terrestrial carbon cycling will become increasingly important in the context of emerging regional and global carbon policies. Close

• 2345. [Article] Egalitarianism and separatism : a history of approaches in the provision of public recreation and leisure service for blacks, 1906-1972

  The purpose of this study was to determine the extent to which the philosophy, administration and implementation of public recreation and leisure service has contributed to the democratization of black Americans ...

  Citation × Citation Citation Abstract Copy Title: Egalitarianism and separatism : a history of approaches in the provision of public recreation and leisure service for blacks, 1906-1972 Author: Murphy, James Frederick The purpose of this study was to determine the extent to which the philosophy, administration and implementation of public recreation and leisure service has contributed to the democratization of black Americans for the period 1906-1972. The study attempted to describe the interplay and connection between the black, subordinated community and the dominant white public administered leisure service organizations and how this relationship has influenced the mode of delivery of public recreation for blacks. The study was undertaken to help the field to more fully understand the consequences of the democratizing effect of recreation and the apparent relationship of continuing public recreation deprivation for black people and urban unrest which does not fit with a consistent pattern of egalitarianism and democracy. Design of the Study The study approach utilized the historical method which mainly involved the data gathering of primary and pertinent secondary material related to the provision of public recreation and leisure service to blacks. The material used in this study was intended to surface important developments, transitions, and approaches to leisure service delivery in order to provide a more sound historical base on which to make future assessments in race relations as it applies to public recreation. A variety of approaches was taken to gather the data analyzed in this study. These approaches included: 1) a comprehensive investigation of related literature; 2) interviews with experts in the field; 3) a personal visit to the library and archives of the National Recreation and Park Association; and 4) the solicitation of informal mail responses from key retired officials of the National Recreation Association and National Recreation and Park Association. The researcher attempted to identify major phases of development in the facilitation of public recreation opportunities for blacks and draw relationships between major social trends as they effected blacks and the recreation movement. These phases of development were summarized in a model of dominant-subordinate relations. The model synthesizes and combines the major societal patterns of dominant-subordinate relations as they relate to blacks and whites, and the patterns of the provision of public recreation and leisure service for blacks during the period 1906-1972. Conclusions From the findings of this study, the following conclusions were drawn: 1. While the recreation movement was initially oriented to meeting the play needs of underprivileged urban youth, the recreation needs of black youth were basically ignored during the first phase (1906-1919) of black/white relations in public recreation. 2. Blacks largely accepted the rationalization for existing pattern of recreation and leisure service during the first phase. Blacks were Left to provide for themselves through their own social agencies- -church, fraternal orders, etc. 3. The traditional egalitarian public recreation service principle of "recreation for all, " was geared primarily to the needs and interests of the dominant white population. 4. The philosophical approach of the recreation movement incorporated the traditional assimilation concept of intergroup relations by supporting local, regional and national dictates in areas of social relations. 5. During the second phase (1920-1954) of black/white relations in public recreation service, special attempts were made to expand recreation facilities and programs for blacks, although primarily on a segregated basis. 6. The leaders of the recreation movement accepted the segregation of blacks as a fact of social relations and attempted to meet their leisure needs through the Bureau of Colored Work and special "colored" divisions of municipal recreation service from 1920 to 1954. 7. Black people have been systematically excluded from participation in. most community sponsored recreation programs because: a) the all-inclusive philosophy of municipal recreation initiated just after World War I moved the focus of leisure service away from delivery to underprivileged youth, and b) the various legal and extra legal discriminatory sanctions in the area of social relations have served to restrict black participation. 8. During the second phase two mutually exclusive paths of segregated organized recreation. service existed. It was during this stage a re-definition of democratic recreation service was employed in the movement and not seen in conflict by its leaders with the "recreation for all" concept of service. 9. The leaders sought to include blacks in the general offerings of the public recreation program, but did not see the separatist paths of public recreation as not conforming to the tenets of egalitarian service principles. Democratic recreation service delivery was adjusted to fit local and regional customs and legal requirements. 10. In actual operation, public recreation and leisure service has reflected the larger pervasive societal patterns of dominant subordinate intergroup relations. 11. The 1954 Supreme Court decision, Brown v. Board of Education, Topeka, Kansas, precipitated the desegregation of public recreation facilities, and eventually led to the improvement of recreational opportunities for black people during the third phase (1955-1965). 12. Attempts to facilitate more equal and inclusive treatment for blacks, particularly since 1954, have been incorporated by most leisure service agencies. 13. Attempts at separate organization, administration and delivery of public recreation during the fourth phase (1966 to present) of black/white relations in public recreation emerged around 1966. These efforts have been consistent with "black power" views for semi-autonomous control over matters of cultural and educational concern. 14. The fourth phase of relations has been characterized by attempts at shared black/white participation in administrative decisions within the total municipal recreation program and community life. 15. Blacks have been almost entirely dependent upon public recreation offerings and leisure service. Recreation is considered a high priority need among the urban poor. 16. The irony of the "recreation for all" approach of public recreation, which has not worked in practice for subordinated blacks, has been the failure of this method to advocate and recognize the particular cultural and social needs and interests of black people. Rioting has resulted from a lack of sensitive dominant white response to the social needs of black ghetto residents and the frustration of black cultural interests. Title: Egalitarianism and separatism : a history of approaches in the provision of public recreation and leisure service for blacks, 1906-1972 Author: Murphy, James Frederick The purpose of this study was to determine the extent to which the philosophy, administration and implementation of public recreation and leisure service has contributed to the democratization of black Americans for the period 1906-1972. The study attempted to describe the interplay and connection between the black, subordinated community and the dominant white public administered leisure service organizations and how this relationship has influenced the mode of delivery of public recreation for blacks. The study was undertaken to help the field to more fully understand the consequences of the democratizing effect of recreation and the apparent relationship of continuing public recreation deprivation for black people and urban unrest which does not fit with a consistent pattern of egalitarianism and democracy. Design of the Study The study approach utilized the historical method which mainly involved the data gathering of primary and pertinent secondary material related to the provision of public recreation and leisure service to blacks. The material used in this study was intended to surface important developments, transitions, and approaches to leisure service delivery in order to provide a more sound historical base on which to make future assessments in race relations as it applies to public recreation. A variety of approaches was taken to gather the data analyzed in this study. These approaches included: 1) a comprehensive investigation of related literature; 2) interviews with experts in the field; 3) a personal visit to the library and archives of the National Recreation and Park Association; and 4) the solicitation of informal mail responses from key retired officials of the National Recreation Association and National Recreation and Park Association. The researcher attempted to identify major phases of development in the facilitation of public recreation opportunities for blacks and draw relationships between major social trends as they effected blacks and the recreation movement. These phases of development were summarized in a model of dominant-subordinate relations. The model synthesizes and combines the major societal patterns of dominant-subordinate relations as they relate to blacks and whites, and the patterns of the provision of public recreation and leisure service for blacks during the period 1906-1972. Conclusions From the findings of this study, the following conclusions were drawn: 1. While the recreation movement was initially oriented to meeting the play needs of underprivileged urban youth, the recreation needs of black youth were basically ignored during the first phase (1906-1919) of black/white relations in public recreation. 2. Blacks largely accepted the rationalization for existing pattern of recreation and leisure service during the first phase. Blacks were Left to provide for themselves through their own social agencies- -church, fraternal orders, etc. 3. The traditional egalitarian public recreation service principle of "recreation for all, " was geared primarily to the needs and interests of the dominant white population. 4. The philosophical approach of the recreation movement incorporated the traditional assimilation concept of intergroup relations by supporting local, regional and national dictates in areas of social relations. 5. During the second phase (1920-1954) of black/white relations in public recreation service, special attempts were made to expand recreation facilities and programs for blacks, although primarily on a segregated basis. 6. The leaders of the recreation movement accepted the segregation of blacks as a fact of social relations and attempted to meet their leisure needs through the Bureau of Colored Work and special "colored" divisions of municipal recreation service from 1920 to 1954. 7. Black people have been systematically excluded from participation in. most community sponsored recreation programs because: a) the all-inclusive philosophy of municipal recreation initiated just after World War I moved the focus of leisure service away from delivery to underprivileged youth, and b) the various legal and extra legal discriminatory sanctions in the area of social relations have served to restrict black participation. 8. During the second phase two mutually exclusive paths of segregated organized recreation. service existed. It was during this stage a re-definition of democratic recreation service was employed in the movement and not seen in conflict by its leaders with the "recreation for all" concept of service. 9. The leaders sought to include blacks in the general offerings of the public recreation program, but did not see the separatist paths of public recreation as not conforming to the tenets of egalitarian service principles. Democratic recreation service delivery was adjusted to fit local and regional customs and legal requirements. 10. In actual operation, public recreation and leisure service has reflected the larger pervasive societal patterns of dominant subordinate intergroup relations. 11. The 1954 Supreme Court decision, Brown v. Board of Education, Topeka, Kansas, precipitated the desegregation of public recreation facilities, and eventually led to the improvement of recreational opportunities for black people during the third phase (1955-1965). 12. Attempts to facilitate more equal and inclusive treatment for blacks, particularly since 1954, have been incorporated by most leisure service agencies. 13. Attempts at separate organization, administration and delivery of public recreation during the fourth phase (1966 to present) of black/white relations in public recreation emerged around 1966. These efforts have been consistent with "black power" views for semi-autonomous control over matters of cultural and educational concern. 14. The fourth phase of relations has been characterized by attempts at shared black/white participation in administrative decisions within the total municipal recreation program and community life. 15. Blacks have been almost entirely dependent upon public recreation offerings and leisure service. Recreation is considered a high priority need among the urban poor. 16. The irony of the "recreation for all" approach of public recreation, which has not worked in practice for subordinated blacks, has been the failure of this method to advocate and recognize the particular cultural and social needs and interests of black people. Rioting has resulted from a lack of sensitive dominant white response to the social needs of black ghetto residents and the frustration of black cultural interests. Close

• 2346. [Article] Seed and seedling ecology of Artemisia tridentata in a restoration context

  The semi-arid sagebrush steppe ecosystem is one of the largest biomes in North America. The steppe provides critical habitat and forage for wildlife and is economically important to recreation and livestock ...

  Citation × Citation Citation Abstract Copy Title: Seed and seedling ecology of Artemisia tridentata in a restoration context Author: Wijayratne, Upekala C. The semi-arid sagebrush steppe ecosystem is one of the largest biomes in North America. The steppe provides critical habitat and forage for wildlife and is economically important to recreation and livestock industries. However, the ecosystem is threatened primarily due to several negative effects associated with expansion of the exotic annual grass Bromus tectorum (cheatgrass). Because of these changes rehabilitation of the habitat is extremely difficult and energy intensive. Restoration of one of the foundation species, Artemisia tridentata (big sagebrush), is a function of seed availability, seed germination, seedling establishment and mature plant survival. Many studies have addressed various aspects of A. tridentata seed germination and mature plant ecophysiology, but gaps in our knowledge include seed bank dynamics and biotic interactions that may hinder seedling survival. The prevalence of large fires in B. tectorum-invaded habitat limits availability of dispersed seeds in the interior of burned areas, leaving pre-existing viable seeds in the soil seed bank as the primary natural seed source. I investigated seed longevity of two A. tridentata subspecies over a 2-year period by retrieving seed bags that were placed at varying depths and sampling soil and litter fractions of the existing seed bank across six locations in the Great Basin. Artemisia tridentata ssp. wyomingensis and A. t. ssp. vaseyana exhibited patterns of a steadily decreasing abundance of viable seeds on the surface and beneath litter, with 100% loss of surface seed viability in 24 months. However, 29-36% (A. t. ssp. wyomingensis) and 30-40% (A. t. ssp. vaseyana) of buried seeds remained viable throughout the duration of the experiment. Abundance of naturally occurring seeds varied considerably among locations and between years across the Great Basin for both subspecies. Loss of viable seeds from the existing seed bank between post-dispersal and pre-dispersal the following season was higher in magnitude for A. t. ssp. wyomingensis soil fractions compared to litter fractions, and higher overall than for A. t. ssp. vaseyana. Access to resources is critical during early spring when resources are plentiful, and this access affects the probability of survival through the summer drought period. Artemisia tridentata resource acquisition may be adversely affected during this time via root interaction mechanisms that are not mediated through resources (interference competition). I examined whether and how root interactions affected growth of A. t. ssp. wyomingensis by forcing its roots to interact with roots of conspecifics, B. tectorum, Elymus wawawaiensis (Snake River wheatgrass), and Agropyron xhybrid (cultivar 'Hycrest'). Activated carbon was used to counteract any potentially negative effects of root exudates. Artemisia tridentata above- and belowground biomass was not affected when grown with E. wawawaiensis or A. xhybrid compared to control seedlings, but root growth rate and branching density decreased when grown with B. tectorum (root growth: p < 0.01; branching density: p = 0.07). These effects did not occur in potting media amended with activated carbon but may have been the result of unintentional fertilization. Roots of A. tridentata seedlings changed direction or stopped growing altogether more often when grown into roots of conspecific seedlings than when contacting roots of other species (p = 0.08). The odds of this occurring decreased when seedlings were grown in activated carbon-amended potting medium. These results suggest that A. tridentata may have a chemical signaling mechanism to avoid roots of conspecifics. I also assessed whether root and shoot competition (resource-mediated or exploitative competition) of the three grass species affected A. t. ssp. wyomingensis seedling growth and survival, and whether root and shoot competition interacted to affect growth. Size-asymmetric competition takes place when a resource is preempted by a larger individual over a smaller individual, and the larger individual receives a disproportionately larger share of the resource for its relative size. Following wildfires, B. tectorum cover can increase significantly more than that of other species, potentially promoting asymmetric aboveground competition between it and A. tridentata seedlings. Root and shoot competition from B. tectorum lowered A. tridentata biomass dramatically compared to that of control seedlings, with shoot competition alone decreasing growth by over 80%. Only full competition from E. wawawaiensis tended to decrease A. tridentata growth compared to control seedlings, while A. xhybrid had no significant effect at all seedling growth. Bromus tectorum had an average of 92% cover and may explain why shoot competition from this species had such a substantial effect, whereas cover of E. wawawaiensis and A. xhybrid was 71% and 43%, respectively. Root and shoot competition did not interact for any of the grasses, indicating that there was no mechanism for positive or negative feedbacks between one form of competition and the other. Competition from shoots is likely not severe enough for asymmetric light competition to occur. The first study provides land managers with a bet-hedging application while the others offer insight into why the seedling life history stage, already vulnerable, has become more so with B. tectorum invasion. Reseeding techniques promoting burial of some A. tridentata seeds in the soil seed bank may increase restoration success by hedging against the potential for failure of establishment in the initial year of seeding. Selective thinning or removal of potential competitors may be required to benefit resource status of A. tridentata seedlings before the summer drought period commences. This is especially important in areas that are dominated by B. tectorum as competition from the annual reduces A. tridentata root growth substantially and may impact its ability to take up soil resources. Title: Seed and seedling ecology of Artemisia tridentata in a restoration context Author: Wijayratne, Upekala C. The semi-arid sagebrush steppe ecosystem is one of the largest biomes in North America. The steppe provides critical habitat and forage for wildlife and is economically important to recreation and livestock industries. However, the ecosystem is threatened primarily due to several negative effects associated with expansion of the exotic annual grass Bromus tectorum (cheatgrass). Because of these changes rehabilitation of the habitat is extremely difficult and energy intensive. Restoration of one of the foundation species, Artemisia tridentata (big sagebrush), is a function of seed availability, seed germination, seedling establishment and mature plant survival. Many studies have addressed various aspects of A. tridentata seed germination and mature plant ecophysiology, but gaps in our knowledge include seed bank dynamics and biotic interactions that may hinder seedling survival. The prevalence of large fires in B. tectorum-invaded habitat limits availability of dispersed seeds in the interior of burned areas, leaving pre-existing viable seeds in the soil seed bank as the primary natural seed source. I investigated seed longevity of two A. tridentata subspecies over a 2-year period by retrieving seed bags that were placed at varying depths and sampling soil and litter fractions of the existing seed bank across six locations in the Great Basin. Artemisia tridentata ssp. wyomingensis and A. t. ssp. vaseyana exhibited patterns of a steadily decreasing abundance of viable seeds on the surface and beneath litter, with 100% loss of surface seed viability in 24 months. However, 29-36% (A. t. ssp. wyomingensis) and 30-40% (A. t. ssp. vaseyana) of buried seeds remained viable throughout the duration of the experiment. Abundance of naturally occurring seeds varied considerably among locations and between years across the Great Basin for both subspecies. Loss of viable seeds from the existing seed bank between post-dispersal and pre-dispersal the following season was higher in magnitude for A. t. ssp. wyomingensis soil fractions compared to litter fractions, and higher overall than for A. t. ssp. vaseyana. Access to resources is critical during early spring when resources are plentiful, and this access affects the probability of survival through the summer drought period. Artemisia tridentata resource acquisition may be adversely affected during this time via root interaction mechanisms that are not mediated through resources (interference competition). I examined whether and how root interactions affected growth of A. t. ssp. wyomingensis by forcing its roots to interact with roots of conspecifics, B. tectorum, Elymus wawawaiensis (Snake River wheatgrass), and Agropyron xhybrid (cultivar 'Hycrest'). Activated carbon was used to counteract any potentially negative effects of root exudates. Artemisia tridentata above- and belowground biomass was not affected when grown with E. wawawaiensis or A. xhybrid compared to control seedlings, but root growth rate and branching density decreased when grown with B. tectorum (root growth: p < 0.01; branching density: p = 0.07). These effects did not occur in potting media amended with activated carbon but may have been the result of unintentional fertilization. Roots of A. tridentata seedlings changed direction or stopped growing altogether more often when grown into roots of conspecific seedlings than when contacting roots of other species (p = 0.08). The odds of this occurring decreased when seedlings were grown in activated carbon-amended potting medium. These results suggest that A. tridentata may have a chemical signaling mechanism to avoid roots of conspecifics. I also assessed whether root and shoot competition (resource-mediated or exploitative competition) of the three grass species affected A. t. ssp. wyomingensis seedling growth and survival, and whether root and shoot competition interacted to affect growth. Size-asymmetric competition takes place when a resource is preempted by a larger individual over a smaller individual, and the larger individual receives a disproportionately larger share of the resource for its relative size. Following wildfires, B. tectorum cover can increase significantly more than that of other species, potentially promoting asymmetric aboveground competition between it and A. tridentata seedlings. Root and shoot competition from B. tectorum lowered A. tridentata biomass dramatically compared to that of control seedlings, with shoot competition alone decreasing growth by over 80%. Only full competition from E. wawawaiensis tended to decrease A. tridentata growth compared to control seedlings, while A. xhybrid had no significant effect at all seedling growth. Bromus tectorum had an average of 92% cover and may explain why shoot competition from this species had such a substantial effect, whereas cover of E. wawawaiensis and A. xhybrid was 71% and 43%, respectively. Root and shoot competition did not interact for any of the grasses, indicating that there was no mechanism for positive or negative feedbacks between one form of competition and the other. Competition from shoots is likely not severe enough for asymmetric light competition to occur. The first study provides land managers with a bet-hedging application while the others offer insight into why the seedling life history stage, already vulnerable, has become more so with B. tectorum invasion. Reseeding techniques promoting burial of some A. tridentata seeds in the soil seed bank may increase restoration success by hedging against the potential for failure of establishment in the initial year of seeding. Selective thinning or removal of potential competitors may be required to benefit resource status of A. tridentata seedlings before the summer drought period commences. This is especially important in areas that are dominated by B. tectorum as competition from the annual reduces A. tridentata root growth substantially and may impact its ability to take up soil resources. Close

• 2347. [Article] The physiology ecology and run diversity of adult Pacific lamprey, Entosphenus tridentatus, during the freshwater spawning migration

  Pacific lamprey, Entosphenus tridentatus, have shown recent and rapid declines in abundance. These anadromous fish return to streams where they mature, spawn and die. It has been inferred that Pacific ...

  Citation × Citation Citation Abstract Copy Title: The physiology ecology and run diversity of adult Pacific lamprey, Entosphenus tridentatus, during the freshwater spawning migration Author: Clemens, Benjamin Jacob, 1976- Pacific lamprey, Entosphenus tridentatus, have shown recent and rapid declines in abundance. These anadromous fish return to streams where they mature, spawn and die. It has been inferred that Pacific lamprey enter freshwater and reside for ~ 1 year before spawning. This long exposure to the freshwater environment may affect the plasticity of the maturation process and the migration timing of Pacific lamprey. Diversity in run times and body size has been observed for Pacific lamprey, yet it is unknown if this diversity is induced by the freshwater environment or if it is genetic. My first goal was to describe the maturation and migration characteristics of adult Pacific lamprey during their freshwater migration. My second goal was to use these data to make an estimation of the run diversity in Pacific lamprey. I conducted three complementary studies, in the laboratory and the field, to achieve these goals. I held immature adult lamprey (non-ripe fish that had ceased parasitic feeding in the ocean and had returned to freshwater) in the laboratory at temperatures that mimicked what these fish would experience in the wild, during the summer (mean: 21.8 °C), and another group of lamprey at cooler temperature (mean: 13.6 °C) to compare maturation timing and characteristics. The warm water group of lamprey showed significantly greater proportional decreases in body mass following temperature exposure than fish in the cooler water. All fish exposed to the warm water matured the following spring (8-10 months later) whereas only about half of the fish from the cool water exposure matured. To understand the migration distances and timing of adult Pacific lamprey, I tracked radio-tagged fish throughout the Willamette Basin above Willamette Falls, Oregon, by airplane and recorded their location. Fish migrated primarily during the spring to early summer period before stopping during the remainder of summer, when peak river temperatures (≥ 20°C) occurred. These fish tended to remain stationary through the fall and winter. However, at least a few fish continued to migrate upstream after September. I monitored maturation characteristics of adult Pacific lamprey, over time at Willamette Falls, Oregon and compared these fish with recent migrants collected from the Pacific Ocean as they entered freshwater. The results suggest a unimodal spawn timing between April and June, at water temperatures < 20 °C. Between July and mid-September, as water temperatures peaked at ~ 25 °C, relatively immature fish for both sexes prevailed. Warm summer temperatures coincided with an increase and prevalence of testicular atrophy in males, and I also observed a large die-off of lamprey during this time. The immature fish had maturation stages and phenotypic characteristics similar to recent migrants collected at the mouth of the Klamath River, suggesting that the immature fish at Willamette Falls would spawn the following year, and spawners in any given year may have been recent migrants during the previous year. However there is a temporal overlap in the spring of immature and mature fish, and I found evidence from gonad histology of maturing fish as they entered the river from the ocean, suggesting that a cohort is comprised of recent migrants that spawn within several weeks of entering freshwater, and another cohort is comprised of recent migrants that mature and spawn at least 1 year later. I hypothesize that the recent migrants that would likely spawn shortly after entering freshwater are akin to a winter or "ocean maturing" steelhead, Oncorhynchus mykiss, that optimizes feeding and growth in the open ocean for a few years before entering freshwater to spawn low in the river system shortly afterwards. Alternatively, these lamprey may be similar to coastal cutthroat trout, O. clarki clarki, that feed and grow in the coastal areas of the ocean for a few months before entering freshwater to spawn. There could be other less apparent explanations as well. I also hypothesize that the lamprey that would likely spawn within ~ 1 year of entering freshwater are akin to a "stream maturing" steelhead that foregoes feeding and growth opportunities, enters freshwater during the summer – fall, and accesses spawning grounds to spawn at temperatures that promote evolutionary fitness via successful spawning the following spring. Based on the results of my research, I hypothesize that warm summer temperatures (> 20 °C) can act as a strong selection factor against stream maturing Pacific lamprey in two ways. First, these temperatures may expedite their maturation, while at the same time slowing their migration. If these hypotheses are true, then I predict an uncoupling of spawn timing with optimal habitat characteristics, that would promote fitness, in the upper watershed. Second, summer temperatures may cause gonad atrophy and death prior to spawning. This scenario may select for ocean maturing Pacific lamprey. Title: The physiology ecology and run diversity of adult Pacific lamprey, Entosphenus tridentatus, during the freshwater spawning migration Author: Clemens, Benjamin Jacob, 1976- Pacific lamprey, Entosphenus tridentatus, have shown recent and rapid declines in abundance. These anadromous fish return to streams where they mature, spawn and die. It has been inferred that Pacific lamprey enter freshwater and reside for ~ 1 year before spawning. This long exposure to the freshwater environment may affect the plasticity of the maturation process and the migration timing of Pacific lamprey. Diversity in run times and body size has been observed for Pacific lamprey, yet it is unknown if this diversity is induced by the freshwater environment or if it is genetic. My first goal was to describe the maturation and migration characteristics of adult Pacific lamprey during their freshwater migration. My second goal was to use these data to make an estimation of the run diversity in Pacific lamprey. I conducted three complementary studies, in the laboratory and the field, to achieve these goals. I held immature adult lamprey (non-ripe fish that had ceased parasitic feeding in the ocean and had returned to freshwater) in the laboratory at temperatures that mimicked what these fish would experience in the wild, during the summer (mean: 21.8 °C), and another group of lamprey at cooler temperature (mean: 13.6 °C) to compare maturation timing and characteristics. The warm water group of lamprey showed significantly greater proportional decreases in body mass following temperature exposure than fish in the cooler water. All fish exposed to the warm water matured the following spring (8-10 months later) whereas only about half of the fish from the cool water exposure matured. To understand the migration distances and timing of adult Pacific lamprey, I tracked radio-tagged fish throughout the Willamette Basin above Willamette Falls, Oregon, by airplane and recorded their location. Fish migrated primarily during the spring to early summer period before stopping during the remainder of summer, when peak river temperatures (≥ 20°C) occurred. These fish tended to remain stationary through the fall and winter. However, at least a few fish continued to migrate upstream after September. I monitored maturation characteristics of adult Pacific lamprey, over time at Willamette Falls, Oregon and compared these fish with recent migrants collected from the Pacific Ocean as they entered freshwater. The results suggest a unimodal spawn timing between April and June, at water temperatures < 20 °C. Between July and mid-September, as water temperatures peaked at ~ 25 °C, relatively immature fish for both sexes prevailed. Warm summer temperatures coincided with an increase and prevalence of testicular atrophy in males, and I also observed a large die-off of lamprey during this time. The immature fish had maturation stages and phenotypic characteristics similar to recent migrants collected at the mouth of the Klamath River, suggesting that the immature fish at Willamette Falls would spawn the following year, and spawners in any given year may have been recent migrants during the previous year. However there is a temporal overlap in the spring of immature and mature fish, and I found evidence from gonad histology of maturing fish as they entered the river from the ocean, suggesting that a cohort is comprised of recent migrants that spawn within several weeks of entering freshwater, and another cohort is comprised of recent migrants that mature and spawn at least 1 year later. I hypothesize that the recent migrants that would likely spawn shortly after entering freshwater are akin to a winter or "ocean maturing" steelhead, Oncorhynchus mykiss, that optimizes feeding and growth in the open ocean for a few years before entering freshwater to spawn low in the river system shortly afterwards. Alternatively, these lamprey may be similar to coastal cutthroat trout, O. clarki clarki, that feed and grow in the coastal areas of the ocean for a few months before entering freshwater to spawn. There could be other less apparent explanations as well. I also hypothesize that the lamprey that would likely spawn within ~ 1 year of entering freshwater are akin to a "stream maturing" steelhead that foregoes feeding and growth opportunities, enters freshwater during the summer – fall, and accesses spawning grounds to spawn at temperatures that promote evolutionary fitness via successful spawning the following spring. Based on the results of my research, I hypothesize that warm summer temperatures (> 20 °C) can act as a strong selection factor against stream maturing Pacific lamprey in two ways. First, these temperatures may expedite their maturation, while at the same time slowing their migration. If these hypotheses are true, then I predict an uncoupling of spawn timing with optimal habitat characteristics, that would promote fitness, in the upper watershed. Second, summer temperatures may cause gonad atrophy and death prior to spawning. This scenario may select for ocean maturing Pacific lamprey. Close

• 2348. [Article] Spatial and temporal distribution of juvenile Steller sea lion (Eumetopias jubatus) predation events in the Gulf of Alaska

  The first objective of this study was to quantify the intensity of space use of 70 juvenile (12-26 months old) Steller sea lions (SSLs) from the western Distinct Population Segment (DPS) in the Kenai Fjord(KF)/Prince ...

  Citation × Citation Citation Abstract Copy Title: Spatial and temporal distribution of juvenile Steller sea lion (Eumetopias jubatus) predation events in the Gulf of Alaska Author: Vazquez, Norma A. The first objective of this study was to quantify the intensity of space use of 70 juvenile (12-26 months old) Steller sea lions (SSLs) from the western Distinct Population Segment (DPS) in the Kenai Fjord(KF)/Prince William Sound (PWS) region of Alaska as derived from externally attached ARGOS satellite transmitter tags. A Bayesian state-space model (SSM) approach was used to process and interpolate the ARGOS-based locations. The resulting tracks were then used to quantify the spatio-temporal distribution of SSLs by way of a gridded utilization distribution (UD) in the study area. Each of six combined two-month UDs had an average of 24 ± 4.16 animals (range: 20-30) contributing around 5,090 ±1,879 filtered locations (range: 2,757-7,593). Results of the bimonthly UDs show juvenile SSL remained within the KF/PWS study region during the tracking period, with the exception of one individual, TJ16 (male), who crossed the 144° W Meridian separating the western and eastern DPS. Furthermore, results revealed that juveniles exhibit different spatial distributions depending on the time of year. They remain confined to a relatively smaller area (6,500-12,075 km²) in the 100% UD months of March through August compared to a larger area of 11,300-22,575 km² in the 100% UD months September through February. In general, in winter (November-April) 90% of observations fell within 30km of the nearest haul-out, whereas in summer (May-October) 90% fell within 20km. A multifactor analysis of covariance (MANCOVA) revealed a significantly higher percent time spent at sea from November through April than May through October (n=63; age as covariate F₁=3.796, p=0.056; season as factor F₁=13.147, p=0.001). Thus, while age contributed to the observed variance, the main effect was clearly by season. The second objective of this study was to characterize the density effects of predator-prey interactions based on the spatial distribution of actual juvenile Steller sea lion predation events in relation to their utilization distribution. Fifteen predation events were detected from archival Life History Transmitter (LHX) tags implanted into a subset of n=36 of the 70 juvenile SSLs. A Bayesian SSM approach was used to process and interpolate the ARGOS locations received post-mortem from LHX tags. The processed tracks were then used to extrapolate the most likely locations of predation events. All 15 predation events occurred in the western DPS from 2008 through 2013. We expected predation events to occur uniformly in all areas for non-specialized predators, and more often in areas of high utilization such as near rookeries and haul-outs for predators that are specialized on SSLs and focus hunting efforts on high use areas. Results suggest the opposite, with four of the 15 predation events occurred in the 91-100% UD, or areas of the lowest relative frequency distribution of animal locations, 3 events occurred in the 81-90% UD, and only 1 event in the 21-30% UD corresponding to an area of higher relative frequency distribution of animal locations. Seven of the 15 predation events occurred outside the UD range, and therefore in areas likely of the lowest relative frequency distribution of animal locations. The winter predation rate was twice that of summer, with 10 predation events during the winter periods (November-April), and 5 events during the summer periods (May-October). Six predation events occurred in January-February. One predation event occurred in March-April, 2 events in May-June, 1 event in July-August, 2 events in September-October, and 3 events in November-December. A Rayleigh test for circular distribution showed a significant difference from uniformity with a mean ordinal date of January 6th (for n=7 animals ≤ 22 months of age), p=0.016). Studying predation in the marine environment comes with many challenges due to limitations in locating and tracking highly mobile marine predators over a long period of time and over a wide geographic range. Previous Steller sea lion studies looking at predation have inherent biases due to only sampling during the summer months and only near rookeries and haul-outs. Our study shows that we can detect predation all year round, including winter, and far away from rookeries and haul-outs. Since juvenile survival is low, and thus poses a significant risk for population-level survival, increased knowledge of the specifics of juvenile SSL space utilization patterns is of vital importance to assessing the importance of predation risk as one of the main drivers of their survivability. This is the first study to relate actual predation events to the intensity of space use of juvenile SSLs in a declining population in the KF/PWS region of Alaska. Title: Spatial and temporal distribution of juvenile Steller sea lion (Eumetopias jubatus) predation events in the Gulf of Alaska Author: Vazquez, Norma A. The first objective of this study was to quantify the intensity of space use of 70 juvenile (12-26 months old) Steller sea lions (SSLs) from the western Distinct Population Segment (DPS) in the Kenai Fjord(KF)/Prince William Sound (PWS) region of Alaska as derived from externally attached ARGOS satellite transmitter tags. A Bayesian state-space model (SSM) approach was used to process and interpolate the ARGOS-based locations. The resulting tracks were then used to quantify the spatio-temporal distribution of SSLs by way of a gridded utilization distribution (UD) in the study area. Each of six combined two-month UDs had an average of 24 ± 4.16 animals (range: 20-30) contributing around 5,090 ±1,879 filtered locations (range: 2,757-7,593). Results of the bimonthly UDs show juvenile SSL remained within the KF/PWS study region during the tracking period, with the exception of one individual, TJ16 (male), who crossed the 144° W Meridian separating the western and eastern DPS. Furthermore, results revealed that juveniles exhibit different spatial distributions depending on the time of year. They remain confined to a relatively smaller area (6,500-12,075 km²) in the 100% UD months of March through August compared to a larger area of 11,300-22,575 km² in the 100% UD months September through February. In general, in winter (November-April) 90% of observations fell within 30km of the nearest haul-out, whereas in summer (May-October) 90% fell within 20km. A multifactor analysis of covariance (MANCOVA) revealed a significantly higher percent time spent at sea from November through April than May through October (n=63; age as covariate F₁=3.796, p=0.056; season as factor F₁=13.147, p=0.001). Thus, while age contributed to the observed variance, the main effect was clearly by season. The second objective of this study was to characterize the density effects of predator-prey interactions based on the spatial distribution of actual juvenile Steller sea lion predation events in relation to their utilization distribution. Fifteen predation events were detected from archival Life History Transmitter (LHX) tags implanted into a subset of n=36 of the 70 juvenile SSLs. A Bayesian SSM approach was used to process and interpolate the ARGOS locations received post-mortem from LHX tags. The processed tracks were then used to extrapolate the most likely locations of predation events. All 15 predation events occurred in the western DPS from 2008 through 2013. We expected predation events to occur uniformly in all areas for non-specialized predators, and more often in areas of high utilization such as near rookeries and haul-outs for predators that are specialized on SSLs and focus hunting efforts on high use areas. Results suggest the opposite, with four of the 15 predation events occurred in the 91-100% UD, or areas of the lowest relative frequency distribution of animal locations, 3 events occurred in the 81-90% UD, and only 1 event in the 21-30% UD corresponding to an area of higher relative frequency distribution of animal locations. Seven of the 15 predation events occurred outside the UD range, and therefore in areas likely of the lowest relative frequency distribution of animal locations. The winter predation rate was twice that of summer, with 10 predation events during the winter periods (November-April), and 5 events during the summer periods (May-October). Six predation events occurred in January-February. One predation event occurred in March-April, 2 events in May-June, 1 event in July-August, 2 events in September-October, and 3 events in November-December. A Rayleigh test for circular distribution showed a significant difference from uniformity with a mean ordinal date of January 6th (for n=7 animals ≤ 22 months of age), p=0.016). Studying predation in the marine environment comes with many challenges due to limitations in locating and tracking highly mobile marine predators over a long period of time and over a wide geographic range. Previous Steller sea lion studies looking at predation have inherent biases due to only sampling during the summer months and only near rookeries and haul-outs. Our study shows that we can detect predation all year round, including winter, and far away from rookeries and haul-outs. Since juvenile survival is low, and thus poses a significant risk for population-level survival, increased knowledge of the specifics of juvenile SSL space utilization patterns is of vital importance to assessing the importance of predation risk as one of the main drivers of their survivability. This is the first study to relate actual predation events to the intensity of space use of juvenile SSLs in a declining population in the KF/PWS region of Alaska. Close

• 2349. [Article] Reproductive implications of parasitic infections and immune challenges in garter snakes

  Parasitic infections and immune challenges can affect host reproductive fitness and, ultimately, the evolution of host populations in a myriad of ways. The fitness implications of parasitic infections ...

  Citation × Citation Citation Abstract Copy Title: Reproductive implications of parasitic infections and immune challenges in garter snakes Author: Uhrig, Emily J. Parasitic infections and immune challenges can affect host reproductive fitness and, ultimately, the evolution of host populations in a myriad of ways. The fitness implications of parasitic infections range from increased host mortality to subtle changes in reproductive investment. From alterations of behaviors, sexual signaling, and competitive ability to changes in gamete production and fertilization success, it is clear that parasites are capable of mediating sexual selection and influencing host reproductive fitness even without altering mortality. The mechanisms underlying fitness effects highlight the complexity of the host-parasite relationship which involves immune responses as well as a range of other, often interactive, physiological processes within the host. In some instances, it is not the direct effect of parasites per se, but rather the hosts' responses to infection that mediate fitness consequences. This dissertation presents studies designed to elucidate the implications of parasitism and immune responses for the reproductive fitness of garter snakes (genus Thamnophis). In chapter 2, "Alaria mesocercariae in the tails of red-sided garter snakes: evidence for parasite-mediated caudectomy", I focus on the histopathological changes associated with a trematode (Alaria sp.) infecting the tails of red-sided garter snakes (T. sirtalis parietalis). My results demonstrate that Alaria mesocercariae occur in high density within the tail tissue of both male and female snakes with as many as 2,000 mesocercariae in a single tail; infection prevalence was 100% in the snakes I examined. I found no evidence of intersexual variation in pathological changes or infection densities. For both sexes, external pathological manifestations include swelling of the tail while, internally, the aggregation of mesocercariae leads to the formation of mucus-filled pseudocysts and damage of muscle tissue. In severe cases, the extent of tissue destruction appeared to weaken the connection of the tail to the rest of the body, a condition that would facilitate tail breakage, which in turn negatively affects the snake's fitness by impairing mating success. From the parasite's perspective, tail breakage is likely beneficial by facilitating its transmission to subsequent hosts in its life cycle. Alaria sp. are not the only parasites commonly infecting garter snakes and in chapter 3, "Patterns in parasitism: interspecific and interpopulational variation in helminth assemblages and their reproductive fitness correlates in garter snakes", I broaden our investigation to include a suite of helminth parasites common in the garter snakes of Manitoba, Canada. My results demonstrate that helminth assemblages of two garter snake species (red-sided garter snakes, T. sirtalis parietalis, and plains garter snakes, T. radix) include Lechriorchis trematodes and Rhabdias nematodes in the lung, Alaria mesocercariae in the tail, and diplostomid trematode metacercariae in the visceral fat; red-sided garter snakes also had gastrointestinal cestodes. Helminth assemblages varied, mainly in terms of parasite density, among populations of red-sided garter snakes and between red-sided and plains garter snakes, but it is unclear whether this variation is due simply to diet-based differences in parasite exposure or whether variation in parasite resistance may have a role. Notably, for plains garter snakes and one red-sided garter snake population I found helminth densities to be predictive of male fitness correlates, namely body condition, testes mass, and sperm counts. Thus, parasitism in garter snakes clearly has important implications for reproductive fitness beyond just influencing tail loss. These results highlight the importance of considering more than a single parasite or single fitness correlate when exploring host-parasite relationships. The consequences of parasitic infections may arise simply through the activation of the host’s immune system rather than the presence of parasites. Thus, in chapter 4, "Changes in reproductive investment and hormone levels in response to an acute immune challenge", I use lipopolysaccharide (LPS) to assess immune-reproductive tradeoffs of male red-sided garter snakes during the breeding season. As LPS is non-pathogenic, I was able to assess the fitness implications of the immune activation itself. My results showed that males depress courtship behaviors and mating success when faced with a single acute immune challenge. For LPS-treated males that did mate, copulatory plug mass was significantly lower compared to controls, while sperm counts did not differ between treatments. This result likely reflects the dissociated breeding pattern of these snakes as spermatogenesis occurs outside the breeding season and, thus, sperm stores were already in place prior to the immune challenge whereas plug material is produced during the breeding season. Further, the LPS treatment was correlated with increased plasma levels of corticosterone, which were 1.8 times higher in LPS-treated males compared to controls, and decreased levels of androgens, which, in LPS-treated males, were only one third as high as androgen levels in control males. Thus, the observed immune-reproduction tradeoff appeared to be hormonally-mediated. Indeed, the low breeding season androgen levels characteristic of this dissociated breeder may have relaxed testosterone-mediated immunosuppression and so facilitate immune-induced suppression of reproductive behaviors. The results of this study highlight the influence of host life history on the consequences of immune activation and also emphasize the complex interactions between the immune, reproductive and endocrine systems. In chapter 5, "Implications of repeated immune challenges in a capital breeder with prolonged hibernation", I again utilized LPS as a means of investigating the implications of immune activation. In this study, I administered a series of LPS injections to male and mated female snakes throughout the summer feeding season, and, for males, into the autumn. Females give birth during the summer and males undergo testicular recrudescence and spermatogenesis during summer and into autumn so these seasons represent important reproductive periods for red-sided garter snakes. Also, as capital breeders, it is during the summer feeding season that snakes of both sexes accumulate the resources upon which they will rely throughout hibernation and the subsequent breeding season. For the most part, my results did not demonstrate clear immune-reproductive tradeoffs. It appears that the absence of tradeoffs may be due to immune-challenged males and gravid female compensating for the immune challenge and maintaining reproductive processes by increasing their food intake, which was not limited during the study. Indeed, LPS-treated gravid females actually had more offspring per litter compared to gravid control females, suggesting that the immune challenge led to greater investment in offspring. In contrast to gravid females, non-gravid females treated with LPS exhibited reduced food intake which may reflect a survival strategy as anorexia during infections tends to be beneficial for survival. Interestingly, the increased food consumption of males did not translate into greater fat stores, but rather higher liver masses which may be indicative of immunopathological changes which should be explored in future studies. Title: Reproductive implications of parasitic infections and immune challenges in garter snakes Author: Uhrig, Emily J. Parasitic infections and immune challenges can affect host reproductive fitness and, ultimately, the evolution of host populations in a myriad of ways. The fitness implications of parasitic infections range from increased host mortality to subtle changes in reproductive investment. From alterations of behaviors, sexual signaling, and competitive ability to changes in gamete production and fertilization success, it is clear that parasites are capable of mediating sexual selection and influencing host reproductive fitness even without altering mortality. The mechanisms underlying fitness effects highlight the complexity of the host-parasite relationship which involves immune responses as well as a range of other, often interactive, physiological processes within the host. In some instances, it is not the direct effect of parasites per se, but rather the hosts' responses to infection that mediate fitness consequences. This dissertation presents studies designed to elucidate the implications of parasitism and immune responses for the reproductive fitness of garter snakes (genus Thamnophis). In chapter 2, "Alaria mesocercariae in the tails of red-sided garter snakes: evidence for parasite-mediated caudectomy", I focus on the histopathological changes associated with a trematode (Alaria sp.) infecting the tails of red-sided garter snakes (T. sirtalis parietalis). My results demonstrate that Alaria mesocercariae occur in high density within the tail tissue of both male and female snakes with as many as 2,000 mesocercariae in a single tail; infection prevalence was 100% in the snakes I examined. I found no evidence of intersexual variation in pathological changes or infection densities. For both sexes, external pathological manifestations include swelling of the tail while, internally, the aggregation of mesocercariae leads to the formation of mucus-filled pseudocysts and damage of muscle tissue. In severe cases, the extent of tissue destruction appeared to weaken the connection of the tail to the rest of the body, a condition that would facilitate tail breakage, which in turn negatively affects the snake's fitness by impairing mating success. From the parasite's perspective, tail breakage is likely beneficial by facilitating its transmission to subsequent hosts in its life cycle. Alaria sp. are not the only parasites commonly infecting garter snakes and in chapter 3, "Patterns in parasitism: interspecific and interpopulational variation in helminth assemblages and their reproductive fitness correlates in garter snakes", I broaden our investigation to include a suite of helminth parasites common in the garter snakes of Manitoba, Canada. My results demonstrate that helminth assemblages of two garter snake species (red-sided garter snakes, T. sirtalis parietalis, and plains garter snakes, T. radix) include Lechriorchis trematodes and Rhabdias nematodes in the lung, Alaria mesocercariae in the tail, and diplostomid trematode metacercariae in the visceral fat; red-sided garter snakes also had gastrointestinal cestodes. Helminth assemblages varied, mainly in terms of parasite density, among populations of red-sided garter snakes and between red-sided and plains garter snakes, but it is unclear whether this variation is due simply to diet-based differences in parasite exposure or whether variation in parasite resistance may have a role. Notably, for plains garter snakes and one red-sided garter snake population I found helminth densities to be predictive of male fitness correlates, namely body condition, testes mass, and sperm counts. Thus, parasitism in garter snakes clearly has important implications for reproductive fitness beyond just influencing tail loss. These results highlight the importance of considering more than a single parasite or single fitness correlate when exploring host-parasite relationships. The consequences of parasitic infections may arise simply through the activation of the host’s immune system rather than the presence of parasites. Thus, in chapter 4, "Changes in reproductive investment and hormone levels in response to an acute immune challenge", I use lipopolysaccharide (LPS) to assess immune-reproductive tradeoffs of male red-sided garter snakes during the breeding season. As LPS is non-pathogenic, I was able to assess the fitness implications of the immune activation itself. My results showed that males depress courtship behaviors and mating success when faced with a single acute immune challenge. For LPS-treated males that did mate, copulatory plug mass was significantly lower compared to controls, while sperm counts did not differ between treatments. This result likely reflects the dissociated breeding pattern of these snakes as spermatogenesis occurs outside the breeding season and, thus, sperm stores were already in place prior to the immune challenge whereas plug material is produced during the breeding season. Further, the LPS treatment was correlated with increased plasma levels of corticosterone, which were 1.8 times higher in LPS-treated males compared to controls, and decreased levels of androgens, which, in LPS-treated males, were only one third as high as androgen levels in control males. Thus, the observed immune-reproduction tradeoff appeared to be hormonally-mediated. Indeed, the low breeding season androgen levels characteristic of this dissociated breeder may have relaxed testosterone-mediated immunosuppression and so facilitate immune-induced suppression of reproductive behaviors. The results of this study highlight the influence of host life history on the consequences of immune activation and also emphasize the complex interactions between the immune, reproductive and endocrine systems. In chapter 5, "Implications of repeated immune challenges in a capital breeder with prolonged hibernation", I again utilized LPS as a means of investigating the implications of immune activation. In this study, I administered a series of LPS injections to male and mated female snakes throughout the summer feeding season, and, for males, into the autumn. Females give birth during the summer and males undergo testicular recrudescence and spermatogenesis during summer and into autumn so these seasons represent important reproductive periods for red-sided garter snakes. Also, as capital breeders, it is during the summer feeding season that snakes of both sexes accumulate the resources upon which they will rely throughout hibernation and the subsequent breeding season. For the most part, my results did not demonstrate clear immune-reproductive tradeoffs. It appears that the absence of tradeoffs may be due to immune-challenged males and gravid female compensating for the immune challenge and maintaining reproductive processes by increasing their food intake, which was not limited during the study. Indeed, LPS-treated gravid females actually had more offspring per litter compared to gravid control females, suggesting that the immune challenge led to greater investment in offspring. In contrast to gravid females, non-gravid females treated with LPS exhibited reduced food intake which may reflect a survival strategy as anorexia during infections tends to be beneficial for survival. Interestingly, the increased food consumption of males did not translate into greater fat stores, but rather higher liver masses which may be indicative of immunopathological changes which should be explored in future studies. Close

• 2350. [Article] Restoring the Columbia River Estuary : Chinook Salmon Recovery and Invasive Species Management

  As highlighted in this study, shallow-water habitats and the prey they provide are important for juvenile salmon in the Columbia River estuary, but the spread of invasive species and large-scale changes ...

  Citation × Citation Citation Abstract Copy Title: Restoring the Columbia River Estuary : Chinook Salmon Recovery and Invasive Species Management Author: Klopfenstein, Rachael As highlighted in this study, shallow-water habitats and the prey they provide are important for juvenile salmon in the Columbia River estuary, but the spread of invasive species and large-scale changes to the estuary influence how these habitats are utilized. Reed canarygrass (Phalaris arundinacea) (“PHAR” hereafter) is a highly invasive aquatic plant species that affects a number of emergent wetland habitats in the upper Columbia River estuary, and is of concern to those trying to restore important shallow-water habitats for juvenile salmon. The presence of PHAR undoubtedly reduces plant diversity, but this study seeked to elucidate how PHAR affects juvenile Chinook Salmon rearing success relative to natural emergent vegetation. The study further evaluated the importance of wetland-deriver prey to juveniles found in shallow-water habitats along a habitat gradient (i.e., back-water channel, confluence, and main stem). We conducted research at a floodplain wetland restoration site in the tidal-fluvial portion of the estuary, where a water control structure is used to manage water levels and the spread of PHAR. The goal of the research was to compare two microhabitats within the floodplain: areas dominated by PHAR and areas dominated by natural emergent vegetation. Using hatchery-raised juvenile Chinook salmon, we designed a series of feeding experiments in artificial enclosures to determine whether invasive PHAR and natural emergent vegetation provide similar foraging and growth opportunities for juvenile salmon. We further identified differences in physical and biological parameters of each habitat (e.g., temperature, dissolved oxygen, and invertebrate community) and examined feeding characteristics (e.g., diet composition and modeled growth rates) for juveniles through a stomach content analysis. Additionally, we conducted beach seining and diet analysis for fish collected along a habitat gradient and compared the diet composition and modeled growth rates between the sample areas. In the floodplain wetland, invertebrate prey compositions from the 2015-2016 (March- June) fallout and emergence traps were similar, but prey abundances and diversity varied seasonally. Across both years, for emergence traps, the average total density (per m²) of invertebrates in the natural vegetation and in PHAR was 154±18 m² and 225±34 m², respectively, and for the fallout traps was 664±95 m² and 662±64 m², respectively. Salmon diets were mostly similar, and a large proportion of diets in both habitats were made up of Copepoda/Cladocera (60-98% composition by biomass). Growth during the net pen experiment differed significantly between the two vegetation types (Kruskal-Wallis: p<0.001), with fish growing more in the natural emergent vegetation. In 2015, juveniles grew an average 6.4 mm FL in the natural emergent vegetation, compared to 4.7 mm FL in PHAR, and consumed fewer Copepoda/Cladocera and more Diptera over the 10 days. In 2016, juveniles grew an average 9.2 mm FL in the natural emergent vegetation compared to 7.6 mm FL in PHAR. In 2016, fish from both habitats consumed a higher abundance of Copepoda/Cladocera and grew more, despite poor water quality conditions at the site. Of the subyearlings (n=170) and yearlings (n=14) collected in habitats adjacent to the floodplain wetland, 48% were of known hatchery origin. Modeled potential growth rates for subyearlings were similar on average between February and May in the back channel, confluence, and main stem, ranging from 0.067–0.07 g/g/d, but the rates varied seasonally. Growth potential was higher in the back channel habitat earlier in the sampling season (February-March), as the modeled daily growth rates were 0.08 g/g/d compared to 0.06 g/g/d in the main stem. All fish collected prior to May were relatively small and unclipped, highlighting the seasonal benefits of shallow-water habitats to support a variety of life-history traits. When comparing modeled growth rates of the juveniles reared at the floodplain wetland compared to the in adjacent habitats, estimates from the floodplain wetland were higher across all months. Restoration of shallow-water habitats is important for the overall health of the estuary, but the effects of large-scale ecosystem changes (e.g., flow regulation and spread invasive species) on salmon recovery and estuary-management decisions are uncertain. For example, water control structures to limit the spread of PHAR also reduce fish access to floodplain habitats, and fewer high-flow events further limit fish access and may facilitate the spread of invasive species. PHAR has been shown to reduce overall plant diversity and, as observed in this study, may provide habitat that is less suitable to juvenile Chinook Salmon. The high density of important prey for salmon found at the site, regardless of the presence of PHAR, and high potential growth measured at the site, emphasize the importance of restoring shallow-water habitats that are accessible to juvenile Chinook Salmon in the upper estuary. Title: Restoring the Columbia River Estuary : Chinook Salmon Recovery and Invasive Species Management Author: Klopfenstein, Rachael As highlighted in this study, shallow-water habitats and the prey they provide are important for juvenile salmon in the Columbia River estuary, but the spread of invasive species and large-scale changes to the estuary influence how these habitats are utilized. Reed canarygrass (Phalaris arundinacea) (“PHAR” hereafter) is a highly invasive aquatic plant species that affects a number of emergent wetland habitats in the upper Columbia River estuary, and is of concern to those trying to restore important shallow-water habitats for juvenile salmon. The presence of PHAR undoubtedly reduces plant diversity, but this study seeked to elucidate how PHAR affects juvenile Chinook Salmon rearing success relative to natural emergent vegetation. The study further evaluated the importance of wetland-deriver prey to juveniles found in shallow-water habitats along a habitat gradient (i.e., back-water channel, confluence, and main stem). We conducted research at a floodplain wetland restoration site in the tidal-fluvial portion of the estuary, where a water control structure is used to manage water levels and the spread of PHAR. The goal of the research was to compare two microhabitats within the floodplain: areas dominated by PHAR and areas dominated by natural emergent vegetation. Using hatchery-raised juvenile Chinook salmon, we designed a series of feeding experiments in artificial enclosures to determine whether invasive PHAR and natural emergent vegetation provide similar foraging and growth opportunities for juvenile salmon. We further identified differences in physical and biological parameters of each habitat (e.g., temperature, dissolved oxygen, and invertebrate community) and examined feeding characteristics (e.g., diet composition and modeled growth rates) for juveniles through a stomach content analysis. Additionally, we conducted beach seining and diet analysis for fish collected along a habitat gradient and compared the diet composition and modeled growth rates between the sample areas. In the floodplain wetland, invertebrate prey compositions from the 2015-2016 (March- June) fallout and emergence traps were similar, but prey abundances and diversity varied seasonally. Across both years, for emergence traps, the average total density (per m²) of invertebrates in the natural vegetation and in PHAR was 154±18 m² and 225±34 m², respectively, and for the fallout traps was 664±95 m² and 662±64 m², respectively. Salmon diets were mostly similar, and a large proportion of diets in both habitats were made up of Copepoda/Cladocera (60-98% composition by biomass). Growth during the net pen experiment differed significantly between the two vegetation types (Kruskal-Wallis: p<0.001), with fish growing more in the natural emergent vegetation. In 2015, juveniles grew an average 6.4 mm FL in the natural emergent vegetation, compared to 4.7 mm FL in PHAR, and consumed fewer Copepoda/Cladocera and more Diptera over the 10 days. In 2016, juveniles grew an average 9.2 mm FL in the natural emergent vegetation compared to 7.6 mm FL in PHAR. In 2016, fish from both habitats consumed a higher abundance of Copepoda/Cladocera and grew more, despite poor water quality conditions at the site. Of the subyearlings (n=170) and yearlings (n=14) collected in habitats adjacent to the floodplain wetland, 48% were of known hatchery origin. Modeled potential growth rates for subyearlings were similar on average between February and May in the back channel, confluence, and main stem, ranging from 0.067–0.07 g/g/d, but the rates varied seasonally. Growth potential was higher in the back channel habitat earlier in the sampling season (February-March), as the modeled daily growth rates were 0.08 g/g/d compared to 0.06 g/g/d in the main stem. All fish collected prior to May were relatively small and unclipped, highlighting the seasonal benefits of shallow-water habitats to support a variety of life-history traits. When comparing modeled growth rates of the juveniles reared at the floodplain wetland compared to the in adjacent habitats, estimates from the floodplain wetland were higher across all months. Restoration of shallow-water habitats is important for the overall health of the estuary, but the effects of large-scale ecosystem changes (e.g., flow regulation and spread invasive species) on salmon recovery and estuary-management decisions are uncertain. For example, water control structures to limit the spread of PHAR also reduce fish access to floodplain habitats, and fewer high-flow events further limit fish access and may facilitate the spread of invasive species. PHAR has been shown to reduce overall plant diversity and, as observed in this study, may provide habitat that is less suitable to juvenile Chinook Salmon. The high density of important prey for salmon found at the site, regardless of the presence of PHAR, and high potential growth measured at the site, emphasize the importance of restoring shallow-water habitats that are accessible to juvenile Chinook Salmon in the upper estuary. Close