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• 131. [Article] Bound by Blackness: African Migration, Black Identity, and Linked Fate in Post-Civil Rights America

  This dissertation explores the identity formation of Ethiopian and Nigerian immigrants, their second generation children, and native born African Americans who reside in the Seattle metropolitan area. ...

  Citation × Citation Citation Abstract Copy Title: Bound by Blackness: African Migration, Black Identity, and Linked Fate in Post-Civil Rights America Author: Abedi-Anim, MeCherri Year: 2017 This dissertation explores the identity formation of Ethiopian and Nigerian immigrants, their second generation children, and native born African Americans who reside in the Seattle metropolitan area. Using boundary formation theory, I argue that African immigrants and their second generation children are developing a shared sense of Black identity and racial solidarity (linked fate) with native born African Americans. This shared Black identity is illustrated through both Africans and African Americans’ recognition of one another as racial group members, the constraints on their Black identities, and their navigation of similar institutional and political contexts. I argue that this is highly suggestive of an expansion of the Black racial boundary, and the reconstitution of Black identity in the post-Civil Rights Era. Despite some boundary contraction within the Black racial category by some 1st generation Africans, the African 1.5 and second generation are engaging in boundary crossing particularly with African Americans through their bicultural identities. This process appears to be leading to the blurring of boundaries between the children of African immigrants and native born African Americans, especially through the 1.5 and second generations involvement and integration into African American social and professional organizations. Evidence presented in this dissertation suggests that there is a weakening of ethnic identity among the African 1.5 and second generation. This weakening of ethnic identity among the children of Ethiopians and Nigerians suggest subsequent generations of Africans born here in the United States will eventually be absorbed into an undifferentiated African American/Black category. Keywords: Ethiopians, Nigerians, African Americans, linked fate, Black identity, Africans Title: Bound by Blackness: African Migration, Black Identity, and Linked Fate in Post-Civil Rights America Author: Abedi-Anim, MeCherri Year: 2017 This dissertation explores the identity formation of Ethiopian and Nigerian immigrants, their second generation children, and native born African Americans who reside in the Seattle metropolitan area. Using boundary formation theory, I argue that African immigrants and their second generation children are developing a shared sense of Black identity and racial solidarity (linked fate) with native born African Americans. This shared Black identity is illustrated through both Africans and African Americans’ recognition of one another as racial group members, the constraints on their Black identities, and their navigation of similar institutional and political contexts. I argue that this is highly suggestive of an expansion of the Black racial boundary, and the reconstitution of Black identity in the post-Civil Rights Era. Despite some boundary contraction within the Black racial category by some 1st generation Africans, the African 1.5 and second generation are engaging in boundary crossing particularly with African Americans through their bicultural identities. This process appears to be leading to the blurring of boundaries between the children of African immigrants and native born African Americans, especially through the 1.5 and second generations involvement and integration into African American social and professional organizations. Evidence presented in this dissertation suggests that there is a weakening of ethnic identity among the African 1.5 and second generation. This weakening of ethnic identity among the children of Ethiopians and Nigerians suggest subsequent generations of Africans born here in the United States will eventually be absorbed into an undifferentiated African American/Black category. Keywords: Ethiopians, Nigerians, African Americans, linked fate, Black identity, Africans Close

• 132. [Article] LRIG1 Localization within the Colonic Crypt of Lrig3 Double Null Mice

  46 pages. A thesis presented to the Department of Biology and the Department of Chemistry and Biochemistry and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements ...

  Citation × Citation Citation Abstract Copy Title: LRIG1 Localization within the Colonic Crypt of Lrig3 Double Null Mice Author: Taylor, Ainsley Lorraine Year: 2017 46 pages. A thesis presented to the Department of Biology and the Department of Chemistry and Biochemistry and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2017 Title: LRIG1 Localization within the Colonic Crypt of Lrig3 Double Null Mice Author: Taylor, Ainsley Lorraine Year: 2017 46 pages. A thesis presented to the Department of Biology and the Department of Chemistry and Biochemistry and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2017 Close

• 133. [Article] Perceived Risk, Stigma, and Potential Economic Impacts of a High-Level Nuclear Waste Repository in Nevada

  41 pages

  Citation × Citation Citation Abstract Copy Title: Perceived Risk, Stigma, and Potential Economic Impacts of a High-Level Nuclear Waste Repository in Nevada Author: Slovic, Paul, Layman, Mark, Kraus, Nancy, Flynn, James, Chalmers, James, Gesell, Gail Year: 2017, 1991 41 pages Title: Perceived Risk, Stigma, and Potential Economic Impacts of a High-Level Nuclear Waste Repository in Nevada Author: Slovic, Paul, Layman, Mark, Kraus, Nancy, Flynn, James, Chalmers, James, Gesell, Gail Year: 2017, 1991 41 pages Close

• 134. [Article] Reflexive gentrification of working lands in the American West : contesting the 'Middle Landscape'

  16 pages

  Citation × Citation Citation Abstract Copy Title: Reflexive gentrification of working lands in the American West : contesting the 'Middle Landscape' Author: Abrams, Jesse, Bliss, John Caswell, Gosnell, Hannah Year: 2017, 2013 16 pages Title: Reflexive gentrification of working lands in the American West : contesting the 'Middle Landscape' Author: Abrams, Jesse, Bliss, John Caswell, Gosnell, Hannah Year: 2017, 2013 16 pages Close

• 135. [Article] Latino Small-Town Revitalization as “Blight”:

  Examining committee: Gerardo Sandoval, chair, Howard Davis

  Citation × Citation Citation Abstract Copy Title: Latino Small-Town Revitalization as “Blight”: Author: Herrera, Roanel Year: 2014, 2013 Examining committee: Gerardo Sandoval, chair, Howard Davis Title: Latino Small-Town Revitalization as “Blight”: Author: Herrera, Roanel Year: 2014, 2013 Examining committee: Gerardo Sandoval, chair, Howard Davis Close

• 136. [Article] Understanding the Importance of Intermittently Fragmented Stream Habitat for Isolated Westslope Cutthroat Trout (<i>Oncorhynchus clarki lewisi</i>) in the Colville National Forest, Washington

  Climate change and anthropogenic effects have vastly reduced Westslope Cutthroat Trout (Oncorhynchus clarki lewisi, WCT) habitat throughout their range, including the Colville National Forest in northeastern ...

  Citation × Citation Citation Abstract Copy Title: Understanding the Importance of Intermittently Fragmented Stream Habitat for Isolated Westslope Cutthroat Trout (<i>Oncorhynchus clarki lewisi</i>) in the Colville National Forest, Washington Author: Carpenter, Forrest Michael Year: 2016 Climate change and anthropogenic effects have vastly reduced Westslope Cutthroat Trout (Oncorhynchus clarki lewisi, WCT) habitat throughout their range, including the Colville National Forest in northeastern Washington where this study was conducted. Many native salmonid populations have declined in abundance since the early 1900s due to a variety of climate- and human-driven forces. Westslope Cutthroat Trout are especially sensitive to habitat loss or degradation and to climate change. Together, climate change, habitat degradation, and non-native salmonid invasions are contributing to increasingly fragmented WCT populations. Ongoing and predicted future warming trends are expected to further fragment these populations and isolate them in headwater stream reaches, with populations in the spatial margins of their distributions facing greater risk. Native salmonid populations are often separated or isolated by natural or artificial upstream migration barriers (i.e., waterfalls, culverts, etc.). Prior to continuing conservation and management actions targeting WCT, it is imperative to understand habitat requirements of this keystone species in fragmented areas. Field survey data were collected in the summer of 2015 on channel geomorphic characteristics and WCT presence/absence in 26 streams located in the Colville National Forest. A clear spatial separation was observed between Eastern Brook Trout (Salvenius fontinalis, EBT) and WCT above four culvert road crossings and the habitat in both of these areas was compared statistically to identify explicit differences. This dataset was also analyzed using logistic regression modeling to determine the best habitat predictors of the presence of isolated WCT populations existing upstream of these crossing. In general, stream habitat in the Middle and South Forks of Mill Creek had low large substrate, high fine sediments, and exhibited pool-riffle channel morphology. Pool habitat supporting isolated WCT was significantly smaller, in terms of volume and surface area, than pool habitat supporting sympatric populations of WCT and EBT, largely due to the headwater nature of channel units supporting isolated WCT populations. Additionally, due to the extreme drought conditions during 2015, stream flow was substantially diminished in the study area causing these reaches to be highly fragmented and largely disconnected from the rest of the stream channel. Fine sediments were generally higher in headwater reaches supporting isolated WCT, including in pools and riffles, which was unexpected, mainly because they exist above sediment delivery points in the longitudinal extent of the system. Logistic regression analysis indicated that the presence of isolated WCT populations was primarily positively associated with an increase in large wood and boulders, and negatively associated with increasing gravel, bedrock, habitat unit length, depth, and width (Significant x2, R2=0.174, misclassification rate = 14.9%, α=0.05). The final model correctly predicted 37.5% of isolated WCT presence observations and 96.5% of the WCT/EBT presence observations significantly better than by chance alone (k=0.81). This model, in fact, may be useful in identifying limited habitat due to the fragmented nature of the channel units supporting IWCT. Large wood and boulders were positively correlated to WCT presence, likely because both are important in the formation of pools and cascades. Channel unit length, width, depth, active channel width as well as gravel and bedrock substrates, were all negatively associated with WCT presence. This suggests that isolated WCT are primarily associated with small headwater cascades with complex shelter, which may provide greater thermal and predation refuge compared to shallow glide or large pool habitats. Future model analysis should include additional habitat variables such as water temperature, stream gradient, and species interactions to strengthen the prediction of Westslope Cutthroat Trout presence. Overall, I concluded that differences in stream habitat above and below blocking culverts are not driving Westslope Cutthroat Trout distributions in the study area due to confounding factors such as the presence of problematic barriers and small sample size. I also conclude that future conservation and management decisions specific to WCT should prioritize complex cascade habitat in headwater stream reaches because of the type and quantity of habitat they may provide, especially during severe drought or low flow conditions. Title: Understanding the Importance of Intermittently Fragmented Stream Habitat for Isolated Westslope Cutthroat Trout (<i>Oncorhynchus clarki lewisi</i>) in the Colville National Forest, Washington Author: Carpenter, Forrest Michael Year: 2016 Climate change and anthropogenic effects have vastly reduced Westslope Cutthroat Trout (Oncorhynchus clarki lewisi, WCT) habitat throughout their range, including the Colville National Forest in northeastern Washington where this study was conducted. Many native salmonid populations have declined in abundance since the early 1900s due to a variety of climate- and human-driven forces. Westslope Cutthroat Trout are especially sensitive to habitat loss or degradation and to climate change. Together, climate change, habitat degradation, and non-native salmonid invasions are contributing to increasingly fragmented WCT populations. Ongoing and predicted future warming trends are expected to further fragment these populations and isolate them in headwater stream reaches, with populations in the spatial margins of their distributions facing greater risk. Native salmonid populations are often separated or isolated by natural or artificial upstream migration barriers (i.e., waterfalls, culverts, etc.). Prior to continuing conservation and management actions targeting WCT, it is imperative to understand habitat requirements of this keystone species in fragmented areas. Field survey data were collected in the summer of 2015 on channel geomorphic characteristics and WCT presence/absence in 26 streams located in the Colville National Forest. A clear spatial separation was observed between Eastern Brook Trout (Salvenius fontinalis, EBT) and WCT above four culvert road crossings and the habitat in both of these areas was compared statistically to identify explicit differences. This dataset was also analyzed using logistic regression modeling to determine the best habitat predictors of the presence of isolated WCT populations existing upstream of these crossing. In general, stream habitat in the Middle and South Forks of Mill Creek had low large substrate, high fine sediments, and exhibited pool-riffle channel morphology. Pool habitat supporting isolated WCT was significantly smaller, in terms of volume and surface area, than pool habitat supporting sympatric populations of WCT and EBT, largely due to the headwater nature of channel units supporting isolated WCT populations. Additionally, due to the extreme drought conditions during 2015, stream flow was substantially diminished in the study area causing these reaches to be highly fragmented and largely disconnected from the rest of the stream channel. Fine sediments were generally higher in headwater reaches supporting isolated WCT, including in pools and riffles, which was unexpected, mainly because they exist above sediment delivery points in the longitudinal extent of the system. Logistic regression analysis indicated that the presence of isolated WCT populations was primarily positively associated with an increase in large wood and boulders, and negatively associated with increasing gravel, bedrock, habitat unit length, depth, and width (Significant x2, R2=0.174, misclassification rate = 14.9%, α=0.05). The final model correctly predicted 37.5% of isolated WCT presence observations and 96.5% of the WCT/EBT presence observations significantly better than by chance alone (k=0.81). This model, in fact, may be useful in identifying limited habitat due to the fragmented nature of the channel units supporting IWCT. Large wood and boulders were positively correlated to WCT presence, likely because both are important in the formation of pools and cascades. Channel unit length, width, depth, active channel width as well as gravel and bedrock substrates, were all negatively associated with WCT presence. This suggests that isolated WCT are primarily associated with small headwater cascades with complex shelter, which may provide greater thermal and predation refuge compared to shallow glide or large pool habitats. Future model analysis should include additional habitat variables such as water temperature, stream gradient, and species interactions to strengthen the prediction of Westslope Cutthroat Trout presence. Overall, I concluded that differences in stream habitat above and below blocking culverts are not driving Westslope Cutthroat Trout distributions in the study area due to confounding factors such as the presence of problematic barriers and small sample size. I also conclude that future conservation and management decisions specific to WCT should prioritize complex cascade habitat in headwater stream reaches because of the type and quantity of habitat they may provide, especially during severe drought or low flow conditions. Close

• 137. [Article] Intestinal Microbiota Diversity of Pre-Smolt Steelhead (Oncorhynchus mykiss) Across Six Oregon and Washington Hatcheries

  The Pacific Northwest is known for its once-abundant wild salmonid populations that have been in decline for more than 50 years due to habitat destruction and commercial overexploitation. To compensate, ...

  Citation × Citation Citation Abstract Copy Title: Intestinal Microbiota Diversity of Pre-Smolt Steelhead (Oncorhynchus mykiss) Across Six Oregon and Washington Hatcheries Author: Yildirimer, Christina Carrell Year: 2017 The Pacific Northwest is known for its once-abundant wild salmonid populations that have been in decline for more than 50 years due to habitat destruction and commercial overexploitation. To compensate, federal and state agencies annually release hundreds of thousands of hatchery-reared fish into the wild. However, accumulating data indicate that hatchery fish have lower fitness in natural environments, and that hatchery rearing negatively influences return rates of anadromous salmonids. Recently, mounting evidence revealed that the richness and diversity of intestinal microbial species influence host health. We examined the gut microbiota of pre-migratory hatchery-reared steelhead (Oncorhynchus mykiss) to assess microbial community diversity. The Cascade Mountains serve as an allopatric border between two distinct clades of steelhead that show significant differences in genomic and mitochondrial diversity. We identified differences in core microbiota of hatchery-reared fish that correlate with this divergent phylogeographic distribution. Steelhead sampled from hatcheries east of the Cascades had overall greater core gut microbiota diversity. These differences were found despite similarities in diet and rearing conditions. In addition to taxonomic variation across the geographic divide, we identified significant differences in metabolic pathways using PICRUSt gene prediction software. Our analysis revealed significant enrichment of genes associated with lipid metabolism in the gut microbiome of western fish. 8 of 19 individual lipid metabolism pathways were more prominent in western populations. Lipids are a vital nutritional component for teleost species involved in migration and subsequent return for spawning in natal environments. We hypothesize that the observed differences in lipid metabolism across this phylogenetic divide results from an increased ability of eastern Cascade (O. m. gairdneri) fish to utilize lipids taken in via the diet. This increased absorption and utilization would make lipids less available for the intestinal microbiota of the eastern fish, as evidenced by the lower abundance of lipid metabolism genes in the east. Our research utilizes information from the microbiome to understand the phenotypic implications occurring in segregated populations of hatchery-reared steelhead, further confirming elements of coevolution between an organism and its internal environment. Title: Intestinal Microbiota Diversity of Pre-Smolt Steelhead (Oncorhynchus mykiss) Across Six Oregon and Washington Hatcheries Author: Yildirimer, Christina Carrell Year: 2017 The Pacific Northwest is known for its once-abundant wild salmonid populations that have been in decline for more than 50 years due to habitat destruction and commercial overexploitation. To compensate, federal and state agencies annually release hundreds of thousands of hatchery-reared fish into the wild. However, accumulating data indicate that hatchery fish have lower fitness in natural environments, and that hatchery rearing negatively influences return rates of anadromous salmonids. Recently, mounting evidence revealed that the richness and diversity of intestinal microbial species influence host health. We examined the gut microbiota of pre-migratory hatchery-reared steelhead (Oncorhynchus mykiss) to assess microbial community diversity. The Cascade Mountains serve as an allopatric border between two distinct clades of steelhead that show significant differences in genomic and mitochondrial diversity. We identified differences in core microbiota of hatchery-reared fish that correlate with this divergent phylogeographic distribution. Steelhead sampled from hatcheries east of the Cascades had overall greater core gut microbiota diversity. These differences were found despite similarities in diet and rearing conditions. In addition to taxonomic variation across the geographic divide, we identified significant differences in metabolic pathways using PICRUSt gene prediction software. Our analysis revealed significant enrichment of genes associated with lipid metabolism in the gut microbiome of western fish. 8 of 19 individual lipid metabolism pathways were more prominent in western populations. Lipids are a vital nutritional component for teleost species involved in migration and subsequent return for spawning in natal environments. We hypothesize that the observed differences in lipid metabolism across this phylogenetic divide results from an increased ability of eastern Cascade (O. m. gairdneri) fish to utilize lipids taken in via the diet. This increased absorption and utilization would make lipids less available for the intestinal microbiota of the eastern fish, as evidenced by the lower abundance of lipid metabolism genes in the east. Our research utilizes information from the microbiome to understand the phenotypic implications occurring in segregated populations of hatchery-reared steelhead, further confirming elements of coevolution between an organism and its internal environment. Close

• 138. [Article] Stewarding Our Mountains: A Program Evaluation of Place-Based Service Learning on the Appalachian Trail

  Appalachians’ relationships with the environment alter over time due to political, economic, and ecological factors. These changing relationships, for instance rural agrarian livelihoods shifting to urban ...

  Citation × Citation Citation Abstract Copy Title: Stewarding Our Mountains: A Program Evaluation of Place-Based Service Learning on the Appalachian Trail Author: Harvey, Bonnie Jean Year: 2016 Appalachians’ relationships with the environment alter over time due to political, economic, and ecological factors. These changing relationships, for instance rural agrarian livelihoods shifting to urban contexts, can influence how an individual perceives personal responsibility in regional environmental stewardship, such as caring for and preserving local ecology. Observing that recent shifts resulted in less perceived youth stewardship for the Appalachian Trail (AT), the Appalachian Trail Conservancy (ATC) created the Trail to Every Classroom (TTEC) program in 2006. The TTEC program attempts to foster stewardship through the practice of place-based service learning - a diversification of education where youth learn through community integrated lessons and local service projects. To date, the ATC had not completed an evaluation of their ability to engender stewardship in its participants. I interned with the ATC for ten weeks and conducted a utilization-focused program evaluation, framing my research questions within the ATC’s Theory of Change model and their organizational goal of creating AT stewardship in TTEC teachers, students, and trail partners. For my analysis I utilized a political ecology theoretical lens to place individuals within their political, economic, and ecological contexts which influence human-environment relationships and potentially individual levels of stewardship. My fieldwork utilized the following techniques: participant observation in TTEC communities (11 total); focus groups with TTEC teachers trained in 2015 (n=16), ATC staff (n=2), TTEC teacher alumni (n=3), and TTEC trail partners from local trail clubs (n=3); surveys from TTEC teachers trained in 2015 (n= 38); semi-structured/structured interviews with alumni TTEC teachers (n=28) and TTEC students (n=124); and TTEC trail partner surveys with local trail clubs and park employees (n=11). Based on the results, I argue that AT stewardship has yet to occur in research participants for three primary reasons: (1) TTEC participants face political, economic, and ecological barriers against accessing public lands and engaging in active, physical outdoor recreation; (2) TTEC participant communities are experiencing socio-economic transitions due to changing industries and migration patterns altering regional land values and human-environment relationships; and (3) the ATC employs an ecocentric (environmental sustainability) model for change while the communities operate within an anthrocentric (human development) model. This project serves as a program evaluation for TTEC’s ongoing organizational development and as a case study example of place-based service learning and environmental stewardship within changing Appalachian communities. Title: Stewarding Our Mountains: A Program Evaluation of Place-Based Service Learning on the Appalachian Trail Author: Harvey, Bonnie Jean Year: 2016 Appalachians’ relationships with the environment alter over time due to political, economic, and ecological factors. These changing relationships, for instance rural agrarian livelihoods shifting to urban contexts, can influence how an individual perceives personal responsibility in regional environmental stewardship, such as caring for and preserving local ecology. Observing that recent shifts resulted in less perceived youth stewardship for the Appalachian Trail (AT), the Appalachian Trail Conservancy (ATC) created the Trail to Every Classroom (TTEC) program in 2006. The TTEC program attempts to foster stewardship through the practice of place-based service learning - a diversification of education where youth learn through community integrated lessons and local service projects. To date, the ATC had not completed an evaluation of their ability to engender stewardship in its participants. I interned with the ATC for ten weeks and conducted a utilization-focused program evaluation, framing my research questions within the ATC’s Theory of Change model and their organizational goal of creating AT stewardship in TTEC teachers, students, and trail partners. For my analysis I utilized a political ecology theoretical lens to place individuals within their political, economic, and ecological contexts which influence human-environment relationships and potentially individual levels of stewardship. My fieldwork utilized the following techniques: participant observation in TTEC communities (11 total); focus groups with TTEC teachers trained in 2015 (n=16), ATC staff (n=2), TTEC teacher alumni (n=3), and TTEC trail partners from local trail clubs (n=3); surveys from TTEC teachers trained in 2015 (n= 38); semi-structured/structured interviews with alumni TTEC teachers (n=28) and TTEC students (n=124); and TTEC trail partner surveys with local trail clubs and park employees (n=11). Based on the results, I argue that AT stewardship has yet to occur in research participants for three primary reasons: (1) TTEC participants face political, economic, and ecological barriers against accessing public lands and engaging in active, physical outdoor recreation; (2) TTEC participant communities are experiencing socio-economic transitions due to changing industries and migration patterns altering regional land values and human-environment relationships; and (3) the ATC employs an ecocentric (environmental sustainability) model for change while the communities operate within an anthrocentric (human development) model. This project serves as a program evaluation for TTEC’s ongoing organizational development and as a case study example of place-based service learning and environmental stewardship within changing Appalachian communities. Close

• 139. [Article] Applications of Remote Sensing to the Study of Estuarine Physics: Suspended Sediment Dynamics in the Columbia River Estuary

  Estuarine circulation and its associated transport processes drive the environmental integrity of many near-shore habitats (the coastal ocean, rivers, estuaries and emergent wetlands). A thorough understanding ...

  Citation × Citation Citation Abstract Copy Title: Applications of Remote Sensing to the Study of Estuarine Physics: Suspended Sediment Dynamics in the Columbia River Estuary Author: Hudson, Austin Scott Year: 2014 Estuarine circulation and its associated transport processes drive the environmental integrity of many near-shore habitats (the coastal ocean, rivers, estuaries and emergent wetlands). A thorough understanding and consideration of this circulation is, therefore, vital in the proper management of these habitats. The aim of this study is to bring together theory and new satellite observations in the Columbia River Estuary to increase our understanding of estuarine circulation and transport. Surface reflectance measurements gathered by the Moderate Imaging Spectroradiometer (MODIS) are first compared to in situ observations to develop an empirical model for remotely derived surface turbidity. Results indicate that MODIS data significantly correlate with in situ measurements of turbidity throughout the CRE (R2 = 0.96). Remote estimates of turbidity are then used to explore the physical processes that drive their spatial distribution. Although the response to different hydrodynamic conditions varies throughout the system, global levels of turbidity are most sensitive to fluvial and tidal inputs and increase during spring tides and high river flow. As a result, the turbidity field has temporal cycles that are consistent with the frequency of these processes. The location of the estuarine turbidity maximum (ETM) is highly dynamic and typically migrates downstream as the tidal velocity or river flow increases. The ETM becomes trapped near the Megler Bridge (river kilometer 20), however, and the presence of strong topography in this region suggests there exists an interaction between bottom topography and sediment transport. A 2-D semi-analytical model, developed herein from the simplified Navier-Stokes equations, confirms that topographic features exhibit substantial influence on longitudinal turbidity distributions. The model considers the coupled, tidally-averaged velocity (composed of gravitational circulation, internal tidal asymmetry, and river flow) and salinity fields and assumes a condition of morphodynamic equilibrium to estimate the distribution of sediment for arbitrary channel configurations. Model simulations demonstrate that topographic highs tend to increase local seaward sediment fluxes, and that topographic lows increase local landward sediment fluxes. Sediment flux convergence near topographic highs compresses the local turbidity distribution, whereas flux divergence near topographic lows dilates the distribution and, under appropriate conditions, produces multiple ETMs. In summary a combination of the model and satellite data has given valuable new insights into the sediment dynamics of estuarine environments; in particular, both show that turbidity distribution and ETM location vary considerably with tidal and river flow conditions, fluctuating on a variety of timescales, and are heavily influenced by bottom topography. Title: Applications of Remote Sensing to the Study of Estuarine Physics: Suspended Sediment Dynamics in the Columbia River Estuary Author: Hudson, Austin Scott Year: 2014 Estuarine circulation and its associated transport processes drive the environmental integrity of many near-shore habitats (the coastal ocean, rivers, estuaries and emergent wetlands). A thorough understanding and consideration of this circulation is, therefore, vital in the proper management of these habitats. The aim of this study is to bring together theory and new satellite observations in the Columbia River Estuary to increase our understanding of estuarine circulation and transport. Surface reflectance measurements gathered by the Moderate Imaging Spectroradiometer (MODIS) are first compared to in situ observations to develop an empirical model for remotely derived surface turbidity. Results indicate that MODIS data significantly correlate with in situ measurements of turbidity throughout the CRE (R2 = 0.96). Remote estimates of turbidity are then used to explore the physical processes that drive their spatial distribution. Although the response to different hydrodynamic conditions varies throughout the system, global levels of turbidity are most sensitive to fluvial and tidal inputs and increase during spring tides and high river flow. As a result, the turbidity field has temporal cycles that are consistent with the frequency of these processes. The location of the estuarine turbidity maximum (ETM) is highly dynamic and typically migrates downstream as the tidal velocity or river flow increases. The ETM becomes trapped near the Megler Bridge (river kilometer 20), however, and the presence of strong topography in this region suggests there exists an interaction between bottom topography and sediment transport. A 2-D semi-analytical model, developed herein from the simplified Navier-Stokes equations, confirms that topographic features exhibit substantial influence on longitudinal turbidity distributions. The model considers the coupled, tidally-averaged velocity (composed of gravitational circulation, internal tidal asymmetry, and river flow) and salinity fields and assumes a condition of morphodynamic equilibrium to estimate the distribution of sediment for arbitrary channel configurations. Model simulations demonstrate that topographic highs tend to increase local seaward sediment fluxes, and that topographic lows increase local landward sediment fluxes. Sediment flux convergence near topographic highs compresses the local turbidity distribution, whereas flux divergence near topographic lows dilates the distribution and, under appropriate conditions, produces multiple ETMs. In summary a combination of the model and satellite data has given valuable new insights into the sediment dynamics of estuarine environments; in particular, both show that turbidity distribution and ETM location vary considerably with tidal and river flow conditions, fluctuating on a variety of timescales, and are heavily influenced by bottom topography. Close

• 140. [Article] Seasonal and Sex Differences in the Effects of Melatonin on Brain Arginine Vasotocin in Green Treefrogs (Hyla cinerea): Relationship to Melatonin Receptor 1a

  Critical life history events such as breeding, migration and hibernation must take place in the correct environmental context to minimize deleterious consequences on survival and reproductive fitness. ...

  Citation × Citation Citation Abstract Copy Title: Seasonal and Sex Differences in the Effects of Melatonin on Brain Arginine Vasotocin in Green Treefrogs (Hyla cinerea): Relationship to Melatonin Receptor 1a Author: Howard, Christina Marie Year: 2014 Critical life history events such as breeding, migration and hibernation must take place in the correct environmental context to minimize deleterious consequences on survival and reproductive fitness. Neuroendocrine mechanisms synchronizing internal physiological states with extrinsic environmental cues are vital to timing life history events appropriately. Secretion of the pineal hormone melatonin is sensitive to light and temperature cues, which provides a physiological indicator of time of day and time of year for organisms. Melatonin influences seasonal reproduction in a variety of vertebrates, likely by altering the synthesis and/or release of reproductive neuropeptides in the brain. The neuropeptides arginine vasotocin and its mammalian homologue, arginine vasopressin, are well-known modulators of reproductive and sociosexual behavior across vertebrate taxa, and are likely targets of melatonin in the context of seasonal reproduction. There is extensive evidence that vasotocin/vasopressin innervation in the brain is subject to seasonal variation, and that this variation is frequently sexually dimorphic. However, evidence that melatonin directly modulates this important neuropeptide system is lacking. Melatonin receptor 1a (MT1 in mammals) may be responsible for mediating melatonin's influence on brain vasotocin, as it is known to regulate seasonal reproduction in a variety of vertebrates. In the present study, I asked whether melatonin influences brain vasotocin in male green treefrogs (Hyla cinerea), and compared the distribution of melatonin receptor 1a in the brain of green treefrogs between sexes and seasons. Adult male and female green treefrogs were collected from field sites in Louisiana during the summer breeding season. Summer animals were acclimated to lab conditions for 3 weeks, then euthanized and their brains collected. Winter animals were maintained in the lab for four months under incrementally changing photo-, thermo-, and hygroperiod regimes that mimicked the transition to winter in their natural habitat, followed by euthanasia and brain collection. A subset of winter males (Experiment 1) were implanted with melatonin-filled or blank silastic capsules for a period of one month prior to euthanasia and brain collection. Brains of these males were processed for vasotocin immunohistochemistry. I quantified AVT-ir cell number in Experiment 1 males in the nucleus accumbens (NAcc), amygdala and caudal striatum (AMG), preoptic area (POA), suprachaismatic nucleus (SCN), and ventral hypothalamus (VH). Melatonin did not influence brain vasotocin-ir cell number in any brain region. Brains from untreated summer and winter males and females were collected and processed for MT1 immunohistochemistry. MT1-ir cells were quantified in the NAcc, striatum (STR), AMG, POA, SCN, and VH. In all regions quantified, reproductively active males had significantly more MT1-ir cells than nonreproductive males. Within the summer breeding season, males had significantly more MT1-ir cells in the NAcc than did reproductively active females. In all other regions there was no significant difference in MT1-ir cell number between reproductively active males and females. Collectively, these data suggest that melatonin modulates vasotocin via MT1. These findings assist in elucidating the neuroendocrine mechanisms by which vertebrates integrate seasonal cues with physiology to correctly time critical life history events. Title: Seasonal and Sex Differences in the Effects of Melatonin on Brain Arginine Vasotocin in Green Treefrogs (Hyla cinerea): Relationship to Melatonin Receptor 1a Author: Howard, Christina Marie Year: 2014 Critical life history events such as breeding, migration and hibernation must take place in the correct environmental context to minimize deleterious consequences on survival and reproductive fitness. Neuroendocrine mechanisms synchronizing internal physiological states with extrinsic environmental cues are vital to timing life history events appropriately. Secretion of the pineal hormone melatonin is sensitive to light and temperature cues, which provides a physiological indicator of time of day and time of year for organisms. Melatonin influences seasonal reproduction in a variety of vertebrates, likely by altering the synthesis and/or release of reproductive neuropeptides in the brain. The neuropeptides arginine vasotocin and its mammalian homologue, arginine vasopressin, are well-known modulators of reproductive and sociosexual behavior across vertebrate taxa, and are likely targets of melatonin in the context of seasonal reproduction. There is extensive evidence that vasotocin/vasopressin innervation in the brain is subject to seasonal variation, and that this variation is frequently sexually dimorphic. However, evidence that melatonin directly modulates this important neuropeptide system is lacking. Melatonin receptor 1a (MT1 in mammals) may be responsible for mediating melatonin's influence on brain vasotocin, as it is known to regulate seasonal reproduction in a variety of vertebrates. In the present study, I asked whether melatonin influences brain vasotocin in male green treefrogs (Hyla cinerea), and compared the distribution of melatonin receptor 1a in the brain of green treefrogs between sexes and seasons. Adult male and female green treefrogs were collected from field sites in Louisiana during the summer breeding season. Summer animals were acclimated to lab conditions for 3 weeks, then euthanized and their brains collected. Winter animals were maintained in the lab for four months under incrementally changing photo-, thermo-, and hygroperiod regimes that mimicked the transition to winter in their natural habitat, followed by euthanasia and brain collection. A subset of winter males (Experiment 1) were implanted with melatonin-filled or blank silastic capsules for a period of one month prior to euthanasia and brain collection. Brains of these males were processed for vasotocin immunohistochemistry. I quantified AVT-ir cell number in Experiment 1 males in the nucleus accumbens (NAcc), amygdala and caudal striatum (AMG), preoptic area (POA), suprachaismatic nucleus (SCN), and ventral hypothalamus (VH). Melatonin did not influence brain vasotocin-ir cell number in any brain region. Brains from untreated summer and winter males and females were collected and processed for MT1 immunohistochemistry. MT1-ir cells were quantified in the NAcc, striatum (STR), AMG, POA, SCN, and VH. In all regions quantified, reproductively active males had significantly more MT1-ir cells than nonreproductive males. Within the summer breeding season, males had significantly more MT1-ir cells in the NAcc than did reproductively active females. In all other regions there was no significant difference in MT1-ir cell number between reproductively active males and females. Collectively, these data suggest that melatonin modulates vasotocin via MT1. These findings assist in elucidating the neuroendocrine mechanisms by which vertebrates integrate seasonal cues with physiology to correctly time critical life history events. Close