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• 11. [Article] The economics of forest-dependent regions

  This dissertation explores two economic phenomena involving forest-dependent areas: wage distribution and migration pattern of individuals. Are forest-dependent rural areas less desirable for workers from ...

  Citation × Citation Citation Abstract Copy Title: The economics of forest-dependent regions Author: Biswas, Smita This dissertation explores two economic phenomena involving forest-dependent areas: wage distribution and migration pattern of individuals. Are forest-dependent rural areas less desirable for workers from the standpoint of labor market returns? Are different skills (e.g. education, experience) rewarded differently in these areas? If there are interregional wage differences, would that influence a working-age individual's migration decision and residential location choice? These questions are examined here with data from Public Use Microdata Survey (PUMS) of the United States 2000 decennial census. I focus my inquiry on the socio-economic characteristics of forest and non forest-dependent areas, the interregional difference in labor market outcomes, and the influence of wage differential and other factors on the migration decisions and residential location choice of working-age individuals. Reduced form log wage equations are estimated for individuals, which incorporate explanatory variables related to both skill factors (such as years of schooling and potential experience) and to non-skill factors (such as minority status) potentially influencing wage. Variations in the interregional wage distribution resulting from differences in skill mix of workers are removed by using a standardized skill distribution. The results indicate that average wages and variation in wage distribution are lower in the forest-dependent areas than other areas. For migration analysis, a Partially Degenerate Nested Logit (PDNL) model is used to model migration decisions and location choice of individuals in the Northwest between 1995 and 2000. Migration decision is modelled as a two stage process: first an individual decides whether to move or stay in his/her original location. Conditional on migration, the individual next chooses his/her destination location from a set of alternative areas. Empirical results indicate that educational attainment and labor market outcomes influence individual's migration decision. Conditional on moving, non-forest dependent areas are more attractive to individuals as residential destinations. Title: The economics of forest-dependent regions Author: Biswas, Smita This dissertation explores two economic phenomena involving forest-dependent areas: wage distribution and migration pattern of individuals. Are forest-dependent rural areas less desirable for workers from the standpoint of labor market returns? Are different skills (e.g. education, experience) rewarded differently in these areas? If there are interregional wage differences, would that influence a working-age individual's migration decision and residential location choice? These questions are examined here with data from Public Use Microdata Survey (PUMS) of the United States 2000 decennial census. I focus my inquiry on the socio-economic characteristics of forest and non forest-dependent areas, the interregional difference in labor market outcomes, and the influence of wage differential and other factors on the migration decisions and residential location choice of working-age individuals. Reduced form log wage equations are estimated for individuals, which incorporate explanatory variables related to both skill factors (such as years of schooling and potential experience) and to non-skill factors (such as minority status) potentially influencing wage. Variations in the interregional wage distribution resulting from differences in skill mix of workers are removed by using a standardized skill distribution. The results indicate that average wages and variation in wage distribution are lower in the forest-dependent areas than other areas. For migration analysis, a Partially Degenerate Nested Logit (PDNL) model is used to model migration decisions and location choice of individuals in the Northwest between 1995 and 2000. Migration decision is modelled as a two stage process: first an individual decides whether to move or stay in his/her original location. Conditional on migration, the individual next chooses his/her destination location from a set of alternative areas. Empirical results indicate that educational attainment and labor market outcomes influence individual's migration decision. Conditional on moving, non-forest dependent areas are more attractive to individuals as residential destinations. Close

• 12. [Article] Internal Migration : The Role of Discrimination and Regionalism in Southern Italians' Self Construction of Identity

  Italian nationalism and an ‘Italian’ identity were constructed during Italy’s unification movement in the mid 1800’s. However, consensus on a national identity is still weak across Italy today. Instead, ...

  Citation × Citation Citation Abstract Copy Title: Internal Migration : The Role of Discrimination and Regionalism in Southern Italians' Self Construction of Identity Author: Spiese, Caroline E. Italian nationalism and an ‘Italian’ identity were constructed during Italy’s unification movement in the mid 1800’s. However, consensus on a national identity is still weak across Italy today. Instead, a polarization of Northern and Southern regions have contributed to discrimination, institutional racism and exclusion. This thesis demonstrates the multifaceted aspects of regionalism and internal migration, and their effects on Southern Italians’ view of identity, regionalism, and how their position as the ‘other’ contributes to their lived experience. This is supported by historical and political background information on Italy and the Emilia-Romagna region, relevant newspaper articles and political cartoons as well as qualitative fieldwork with Southern Italian migrants living in the northern city of Ferrara. This ethnographic case study highlights the growing global trends of regionalism and migration, in order to discover how migrants shape their regional identities. Title: Internal Migration : The Role of Discrimination and Regionalism in Southern Italians' Self Construction of Identity Author: Spiese, Caroline E. Italian nationalism and an ‘Italian’ identity were constructed during Italy’s unification movement in the mid 1800’s. However, consensus on a national identity is still weak across Italy today. Instead, a polarization of Northern and Southern regions have contributed to discrimination, institutional racism and exclusion. This thesis demonstrates the multifaceted aspects of regionalism and internal migration, and their effects on Southern Italians’ view of identity, regionalism, and how their position as the ‘other’ contributes to their lived experience. This is supported by historical and political background information on Italy and the Emilia-Romagna region, relevant newspaper articles and political cartoons as well as qualitative fieldwork with Southern Italian migrants living in the northern city of Ferrara. This ethnographic case study highlights the growing global trends of regionalism and migration, in order to discover how migrants shape their regional identities. Close

• 13. [Article] Fish or Flight: The Impact of Transferable Permits on the Migration Decisions of Rural Alaskan Salmon Harvesters

  This research incorporates unique household survey data and a discrete shift in fisheries management into a model of migration in order to analyze the drivers of outmigration in rural Alaskan communities ...

  Citation × Citation Citation Abstract Copy Title: Fish or Flight: The Impact of Transferable Permits on the Migration Decisions of Rural Alaskan Salmon Harvesters Author: Meredith, Jennifer This research incorporates unique household survey data and a discrete shift in fisheries management into a model of migration in order to analyze the drivers of outmigration in rural Alaskan communities that traditionally depend on fisheries for income. Although there is evidence that a transition to rights-based management decreases the degree of local participation in fisheries as rural residents sell their allocations to outsiders with higher capital endowments, little is known about how these large lump-sum payments affect migration and assets. The implementation of a limited entry permit system in the Alaska salmon fishery allows us to examine how harvesters who reside in rural Alaskan communities respond to such allocations and to test whether these management shifts generate an outflow of migration, potentially undermining the resilience of small communities. A model of migration that integrates fluctuations in fishery returns and transactions within permit markets is tested using individual responses to a household survey conducted with randomly sampled respondents from 10 communities around Bristol Bay.  Although the immediate impact of permit sales on migration appears to be negligible, there is evidence of intergenerational spillovers with descendants being less likely to reside in the region, participate in the fishery, and own durable assets. Title: Fish or Flight: The Impact of Transferable Permits on the Migration Decisions of Rural Alaskan Salmon Harvesters Author: Meredith, Jennifer This research incorporates unique household survey data and a discrete shift in fisheries management into a model of migration in order to analyze the drivers of outmigration in rural Alaskan communities that traditionally depend on fisheries for income. Although there is evidence that a transition to rights-based management decreases the degree of local participation in fisheries as rural residents sell their allocations to outsiders with higher capital endowments, little is known about how these large lump-sum payments affect migration and assets. The implementation of a limited entry permit system in the Alaska salmon fishery allows us to examine how harvesters who reside in rural Alaskan communities respond to such allocations and to test whether these management shifts generate an outflow of migration, potentially undermining the resilience of small communities. A model of migration that integrates fluctuations in fishery returns and transactions within permit markets is tested using individual responses to a household survey conducted with randomly sampled respondents from 10 communities around Bristol Bay.  Although the immediate impact of permit sales on migration appears to be negligible, there is evidence of intergenerational spillovers with descendants being less likely to reside in the region, participate in the fishery, and own durable assets. Close

• 14. [Article] Migration, movement, and habitat use of humpback whitefish (Coregonus pidschian) in the Copper River Delta, Alaska

  Research conducted on humpback whitefish Coregonus pidschian in the Copper River Delta, Alaska has revealed a complex life history involving seasonal migrations and the occupation of a variety of freshwater ...

  Citation × Citation Citation Abstract Copy Title: Migration, movement, and habitat use of humpback whitefish (Coregonus pidschian) in the Copper River Delta, Alaska Author: Neilson, Brian J. Research conducted on humpback whitefish Coregonus pidschian in the Copper River Delta, Alaska has revealed a complex life history involving seasonal migrations and the occupation of a variety of freshwater and marine habitats including lacustrine, riverine, estuarine, and marine. Forty-five whitefish were tagged with radio transmitters in 2006 and 2007, and another 29 whitefish were tagged with acoustic tags in 2008. In addition, otolith chemistry was used to evaluate marine habitat use of humpback whitefish sampled from McKinley Lake in the Copper River Delta, Alaska. Movements and migration of tagged fish were tracked using biotelemetry techniques from boats, airplanes, and fixed receiver stations throughout the spring, summer, and fall. Sagittal otoliths were extracted from 20 humpback whitefish and a chemical analysis was performed to evaluate levels of Sr:Ca. Biotelemetry and sampling results revealed seasonal migrations where humpback whitefish migrated into McKinley Lake in mid to late spring and left the lake by late summer and early fall. Fish migrated to the Copper River in the fall by traveling down Alaganik Slough and then to the Copper River by traveling through Pete Dahl Cutoff Slough or the Gulf of Alaska. Fish travel up the Copper River presumably to their spawning grounds. Nine tagged fish returned to McKinley Lake in 2007 and four tagged fish in 2008, indicating some fidelity to the summer feeding site. Otolith chemistry detected marine migrations in 45% of the samples. Three migratory behaviors were observed, while some individuals inhabited only freshwater environments, some individuals made single migrations to marine habitats, and other individuals made multiple migrations to marine habitats. Age of whitefish ranged from 2 to 9 years. Analysis of small-scale movement of humpback whitefish in McKinley Lake found movement rates to be significantly higher at dusk compared to night in one sampling period. However, diel movement activity in all other diel periods did not significantly differ, suggesting arrhythmic diel movement. A large portion of the lake was occupied at any given time, but not all areas were used equally. Activity levels, measured by change in zones, were variable between dates and indicated that fish often moved between detection zones. An increase in activity was observed in individuals 48 h prior to migration from the lake. This study provides the first documentation of migration, movement, and habitat use of humpback whitefish in the Copper River Delta, Alaska. Results of this study will help inform management of humpback whitefish in order to sustain populations into the future. This information should be considered in land use and species management planning in the Copper River basin including fish passage and harvest regulations. Title: Migration, movement, and habitat use of humpback whitefish (Coregonus pidschian) in the Copper River Delta, Alaska Author: Neilson, Brian J. Research conducted on humpback whitefish Coregonus pidschian in the Copper River Delta, Alaska has revealed a complex life history involving seasonal migrations and the occupation of a variety of freshwater and marine habitats including lacustrine, riverine, estuarine, and marine. Forty-five whitefish were tagged with radio transmitters in 2006 and 2007, and another 29 whitefish were tagged with acoustic tags in 2008. In addition, otolith chemistry was used to evaluate marine habitat use of humpback whitefish sampled from McKinley Lake in the Copper River Delta, Alaska. Movements and migration of tagged fish were tracked using biotelemetry techniques from boats, airplanes, and fixed receiver stations throughout the spring, summer, and fall. Sagittal otoliths were extracted from 20 humpback whitefish and a chemical analysis was performed to evaluate levels of Sr:Ca. Biotelemetry and sampling results revealed seasonal migrations where humpback whitefish migrated into McKinley Lake in mid to late spring and left the lake by late summer and early fall. Fish migrated to the Copper River in the fall by traveling down Alaganik Slough and then to the Copper River by traveling through Pete Dahl Cutoff Slough or the Gulf of Alaska. Fish travel up the Copper River presumably to their spawning grounds. Nine tagged fish returned to McKinley Lake in 2007 and four tagged fish in 2008, indicating some fidelity to the summer feeding site. Otolith chemistry detected marine migrations in 45% of the samples. Three migratory behaviors were observed, while some individuals inhabited only freshwater environments, some individuals made single migrations to marine habitats, and other individuals made multiple migrations to marine habitats. Age of whitefish ranged from 2 to 9 years. Analysis of small-scale movement of humpback whitefish in McKinley Lake found movement rates to be significantly higher at dusk compared to night in one sampling period. However, diel movement activity in all other diel periods did not significantly differ, suggesting arrhythmic diel movement. A large portion of the lake was occupied at any given time, but not all areas were used equally. Activity levels, measured by change in zones, were variable between dates and indicated that fish often moved between detection zones. An increase in activity was observed in individuals 48 h prior to migration from the lake. This study provides the first documentation of migration, movement, and habitat use of humpback whitefish in the Copper River Delta, Alaska. Results of this study will help inform management of humpback whitefish in order to sustain populations into the future. This information should be considered in land use and species management planning in the Copper River basin including fish passage and harvest regulations. Close

• 15. [Article] The morphological events during the self-reassembly of the sea urchin embryo in culture

  The gastrula of the sea urchin Strongylocentrotus purpuratus was dissociated into single cells. In culture these cells appeared apolar, but reassembled into quasi-normal embryos composed of structures ...

  Citation × Citation Citation Abstract Copy Title: The morphological events during the self-reassembly of the sea urchin embryo in culture Author: Hamada, Spencer Hiroshi The gastrula of the sea urchin Strongylocentrotus purpuratus was dissociated into single cells. In culture these cells appeared apolar, but reassembled into quasi-normal embryos composed of structures with polarized cells. In this study emphasis was placed on those morphological events coincident with the reestablishment of a polar orientation within the epithelial cells. Using both time-lapse dark-field-phase microscopy and electron microscopy, the major morphological events followed in detail include: (a) the migration of lysosome-like vesicles to specific margins within the epithelial cells; (b) the migration of the epithelial cells during the re-construction of the epithelium: and (c) the reformation of the cell junctions between the epithelial cells. Evidence indicates that: (1) The orientation resulting from the migration of the lysosome-like vesicles is transient and may not determine any lasting polarity of the epithelial cell. The sequential migration of the lysosome-like vesicles first to the epithelial cell to cell interface, then to the basal margin and finally to the apical margin of the epithelial cell was coincident with and apparently in response to the presence of cell debris often trapped at these sites. The Lysosome-like vesicles formed tight clusters along the epithelial cellular margins where phagocytosis of cell debris and resorption of specialized structures occurred. In contrast, the mesenchyme cell had smaller numbers of phagosomes and lysosome-like vesicles and was observed to participate to a more limited degree in phagocytosis and resorption. (2) The orientation resulting from the formation of a leading edge during the migration of the epithelial cell is transient. The sequence of cytological events associated with epithelial cell migration included the formation of: (a) hyaloplasmic blebs along the cell free margin; (b) filopodia and microvilli; and (c) lamellae with a number of lamellipodia at the leading edge. In contrast, the mesenchyme cell formed filopodia on a smaller scale and was observed to participate in migration only to a limited degree. Coincident with the cessation of epithelial cell migration was the enlargement of the lamella between the epithelial cells into a hyaloplasmic sheet which forms the blastocoel wall. Embryonic cells from reassembling aggregates were cultured as monolayers on glass treated with an adhesion enhancing factor derived from the incubation medium. Cords of cells, composed of both epithelial and mesenchyme cells migrate away from the aggregate and leave in their wake clusters of cells. Epithelial cells were found at the leading margins of these cell cords and were observed forming cytoplasmic blebs, filopodia and hyaloplasmic leading edges during the migration of the cell cord. No apparent coordinate orientation was detectable within the epithelial cells of the migrating cell cord or stationary cell cluster. A hypothesis is presented suggesting a role for resorption during epithelial cell migration. (3) Cell contacts formed during reaggregation become more adhesive as development proceeds. The sequence of fine structural events associated with cell contact formation include the formation of (a) a non--junctional cell apposition, which was characterized by parallel apposed membranes; (b) an incipient continuous junction, which was characterized by parallel apposed membranes; and (c) a continuous junction, which was characterized by the presence of an electron dense region both superjacent and subjacent to the plasma membrane at the site of the junction. The cell appositions between premigratory cells were easier to disrupt mechanically than the later forming continuous junctions. The forming continuous junction was first focal in extent and later zonal in girth around the apical margin of the epithelial cell. Concurrent with the formation of the strongly adhesive continuous junction by the lamella was a cessation of epithelial cell migration, followed by an expression of an apical-basal polarity within the epithelial cell. A hypothesis is presented suggesting a role for cell contacts during the coordinated orientation of the epithelia during the formation of the blastocoel wall. Title: The morphological events during the self-reassembly of the sea urchin embryo in culture Author: Hamada, Spencer Hiroshi The gastrula of the sea urchin Strongylocentrotus purpuratus was dissociated into single cells. In culture these cells appeared apolar, but reassembled into quasi-normal embryos composed of structures with polarized cells. In this study emphasis was placed on those morphological events coincident with the reestablishment of a polar orientation within the epithelial cells. Using both time-lapse dark-field-phase microscopy and electron microscopy, the major morphological events followed in detail include: (a) the migration of lysosome-like vesicles to specific margins within the epithelial cells; (b) the migration of the epithelial cells during the re-construction of the epithelium: and (c) the reformation of the cell junctions between the epithelial cells. Evidence indicates that: (1) The orientation resulting from the migration of the lysosome-like vesicles is transient and may not determine any lasting polarity of the epithelial cell. The sequential migration of the lysosome-like vesicles first to the epithelial cell to cell interface, then to the basal margin and finally to the apical margin of the epithelial cell was coincident with and apparently in response to the presence of cell debris often trapped at these sites. The Lysosome-like vesicles formed tight clusters along the epithelial cellular margins where phagocytosis of cell debris and resorption of specialized structures occurred. In contrast, the mesenchyme cell had smaller numbers of phagosomes and lysosome-like vesicles and was observed to participate to a more limited degree in phagocytosis and resorption. (2) The orientation resulting from the formation of a leading edge during the migration of the epithelial cell is transient. The sequence of cytological events associated with epithelial cell migration included the formation of: (a) hyaloplasmic blebs along the cell free margin; (b) filopodia and microvilli; and (c) lamellae with a number of lamellipodia at the leading edge. In contrast, the mesenchyme cell formed filopodia on a smaller scale and was observed to participate in migration only to a limited degree. Coincident with the cessation of epithelial cell migration was the enlargement of the lamella between the epithelial cells into a hyaloplasmic sheet which forms the blastocoel wall. Embryonic cells from reassembling aggregates were cultured as monolayers on glass treated with an adhesion enhancing factor derived from the incubation medium. Cords of cells, composed of both epithelial and mesenchyme cells migrate away from the aggregate and leave in their wake clusters of cells. Epithelial cells were found at the leading margins of these cell cords and were observed forming cytoplasmic blebs, filopodia and hyaloplasmic leading edges during the migration of the cell cord. No apparent coordinate orientation was detectable within the epithelial cells of the migrating cell cord or stationary cell cluster. A hypothesis is presented suggesting a role for resorption during epithelial cell migration. (3) Cell contacts formed during reaggregation become more adhesive as development proceeds. The sequence of fine structural events associated with cell contact formation include the formation of (a) a non--junctional cell apposition, which was characterized by parallel apposed membranes; (b) an incipient continuous junction, which was characterized by parallel apposed membranes; and (c) a continuous junction, which was characterized by the presence of an electron dense region both superjacent and subjacent to the plasma membrane at the site of the junction. The cell appositions between premigratory cells were easier to disrupt mechanically than the later forming continuous junctions. The forming continuous junction was first focal in extent and later zonal in girth around the apical margin of the epithelial cell. Concurrent with the formation of the strongly adhesive continuous junction by the lamella was a cessation of epithelial cell migration, followed by an expression of an apical-basal polarity within the epithelial cell. A hypothesis is presented suggesting a role for cell contacts during the coordinated orientation of the epithelia during the formation of the blastocoel wall. Close

• 16. [Article] Contribution of subyearling estuarine migrant coho salmon (Oncorhynchus kisutch) to spawning populations on the southern Oregon coast

  The typical coho salmon life history has been characterized by juvenile fish that spend their entire first year in freshwater habitats before migrating into estuaries as smolts. However, reports of early ...

  Citation × Citation Citation Abstract Copy Title: Contribution of subyearling estuarine migrant coho salmon (Oncorhynchus kisutch) to spawning populations on the southern Oregon coast Author: Nordholm, Katherine E. The typical coho salmon life history has been characterized by juvenile fish that spend their entire first year in freshwater habitats before migrating into estuaries as smolts. However, reports of early migrating coho fry (age 0), including migration downstream to estuarine habitats, date back to the 1960s. Until a few years ago, these individuals were considered to be displaced surplus fish with low chances of survival. Recent studies have suggested that subyearling estuarine migrating coho salmon could be an alternative life history in coastal populations, but their return as jacks or mature adults needed to be documented for this life history to be considered a viable strategy. The goal of our study was to track the return of spawning coho salmon that had been individually tagged in either estuarine or riverine nursery habitats, and determine return percentages for each life history strategy as well as independently verify the presence of subyearling estuarine migrating coho salmon through otolith analysis on spawning populations. We used Passive Integrated Transponder (PIT) tags to identify individual fish as they passed through a series of antennas deployed in two coastal lowland streams on the southern Oregon coast. Percentage return of estuary tagged parr (fish ≥ 60 mm tagged in spring and summer of their first year) was variable between years and streams. For the 2010 return year, subyearling estuarine migrants was 2.5 times higher than stream residents in Palouse Creek. Fork length at estuary entrance was reconstructed for one return year of spawning fish based on otolith Sr:Ca and Br:Ca. Four main life history strategies were identified based on their fork length at time of estuary/ocean entrance: early migrating fry (< 60 mm fork length), early migrating parr (60 - 70 mm fork length), early migrating parr that returned to freshwater before migrating as yearlings ("nomads"), and yearling migrating smolts (> 70 mm fork length). Overall, 30% (Larson Creek) to 42% (Palouse Creek) of the 2009 spawning run was made up of fish that displayed evidence of estuarine residence during their first year. This study confirms that subyearling estuarine migrating coho salmon survive to reproductive age and contribute to subsequent generations. The survival of this life history type likely varies between years with changing ocean and stream conditions. It is hypothesized that their life history serves as a "bet hedging" strategy that supports coastal populations in years of poor stream conditions. In the face of rising sea levels, this life history may represent a key to the future viability of coho salmon stocks in coastal watersheds. Title: Contribution of subyearling estuarine migrant coho salmon (Oncorhynchus kisutch) to spawning populations on the southern Oregon coast Author: Nordholm, Katherine E. The typical coho salmon life history has been characterized by juvenile fish that spend their entire first year in freshwater habitats before migrating into estuaries as smolts. However, reports of early migrating coho fry (age 0), including migration downstream to estuarine habitats, date back to the 1960s. Until a few years ago, these individuals were considered to be displaced surplus fish with low chances of survival. Recent studies have suggested that subyearling estuarine migrating coho salmon could be an alternative life history in coastal populations, but their return as jacks or mature adults needed to be documented for this life history to be considered a viable strategy. The goal of our study was to track the return of spawning coho salmon that had been individually tagged in either estuarine or riverine nursery habitats, and determine return percentages for each life history strategy as well as independently verify the presence of subyearling estuarine migrating coho salmon through otolith analysis on spawning populations. We used Passive Integrated Transponder (PIT) tags to identify individual fish as they passed through a series of antennas deployed in two coastal lowland streams on the southern Oregon coast. Percentage return of estuary tagged parr (fish ≥ 60 mm tagged in spring and summer of their first year) was variable between years and streams. For the 2010 return year, subyearling estuarine migrants was 2.5 times higher than stream residents in Palouse Creek. Fork length at estuary entrance was reconstructed for one return year of spawning fish based on otolith Sr:Ca and Br:Ca. Four main life history strategies were identified based on their fork length at time of estuary/ocean entrance: early migrating fry (< 60 mm fork length), early migrating parr (60 - 70 mm fork length), early migrating parr that returned to freshwater before migrating as yearlings ("nomads"), and yearling migrating smolts (> 70 mm fork length). Overall, 30% (Larson Creek) to 42% (Palouse Creek) of the 2009 spawning run was made up of fish that displayed evidence of estuarine residence during their first year. This study confirms that subyearling estuarine migrating coho salmon survive to reproductive age and contribute to subsequent generations. The survival of this life history type likely varies between years with changing ocean and stream conditions. It is hypothesized that their life history serves as a "bet hedging" strategy that supports coastal populations in years of poor stream conditions. In the face of rising sea levels, this life history may represent a key to the future viability of coho salmon stocks in coastal watersheds. Close

• 17. [Article] Source of cobalt-60 and migrations of albacore off the west coast of north America

  Citation × Citation Citation Abstract Copy Title: Source of cobalt-60 and migrations of albacore off the west coast of north America Author: Pearcy, William G., Krygier, Earl E. Title: Source of cobalt-60 and migrations of albacore off the west coast of north America Author: Pearcy, William G., Krygier, Earl E. Close

• 18. [Article] Modeling carbohydrate ballasting by Trichodesmium spp.

  We report the development of a numerical model simulating vertical movement of the cyanobacterium Trichodesmium spp. Given a range of physiological parameters derived from the literature, resultant model ...

  Citation × Citation Citation Abstract Copy Title: Modeling carbohydrate ballasting by Trichodesmium spp. Author: Spitz, Yvette H., Letelier, Ricardo M., White, Angelicque E. We report the development of a numerical model simulating vertical movement of the cyanobacterium Trichodesmium spp. Given a range of physiological parameters derived from the literature, resultant model solutions allow us to explore the ecological significance of vertical migration by Trichodesmium colonies in a stratified oligotrophic oceanic system such as the North Pacific subtropical gyre (NPSG). Whereas the dominant type of model solution results in trapping of the migrating colony at the water surface, the next most frequent type of model solution is consistent with colony migration to the average depth of the phosphocline, followed by return to the upper euphotic zone, a scenario termed P-mining. Given the temporal phasing of these migrations, our results indicate that while Trichodesmium colonies could fulfill their entire P-quota in a single phosphoclinescale migration, the minimal colony size required for such a migration would be approximately 1000 μm in radius. Colonies of this size and larger have been observed in nature. However, neither the frequency of occurrence nor the relative size distributions of natural populations is known. Using published estimates of colony abundance at Station ALOHA (22° 45’ N, 158° 00’W, in the NPSG), we estimate that upward fluxes of P associated with Trichodesmium migration represent as much as 10% of the P-based export flux measured at this site. Inclusion of this simple model into coupled biophysical models should allow for better simulations of the vertical distribution of Trichodesmium biomass and thus improved representations of Trichodesmium productivity. Title: Modeling carbohydrate ballasting by Trichodesmium spp. Author: Spitz, Yvette H., Letelier, Ricardo M., White, Angelicque E. We report the development of a numerical model simulating vertical movement of the cyanobacterium Trichodesmium spp. Given a range of physiological parameters derived from the literature, resultant model solutions allow us to explore the ecological significance of vertical migration by Trichodesmium colonies in a stratified oligotrophic oceanic system such as the North Pacific subtropical gyre (NPSG). Whereas the dominant type of model solution results in trapping of the migrating colony at the water surface, the next most frequent type of model solution is consistent with colony migration to the average depth of the phosphocline, followed by return to the upper euphotic zone, a scenario termed P-mining. Given the temporal phasing of these migrations, our results indicate that while Trichodesmium colonies could fulfill their entire P-quota in a single phosphoclinescale migration, the minimal colony size required for such a migration would be approximately 1000 μm in radius. Colonies of this size and larger have been observed in nature. However, neither the frequency of occurrence nor the relative size distributions of natural populations is known. Using published estimates of colony abundance at Station ALOHA (22° 45’ N, 158° 00’W, in the NPSG), we estimate that upward fluxes of P associated with Trichodesmium migration represent as much as 10% of the P-based export flux measured at this site. Inclusion of this simple model into coupled biophysical models should allow for better simulations of the vertical distribution of Trichodesmium biomass and thus improved representations of Trichodesmium productivity. Close

• 19. [Article] Out-migration, income and poverty in nonmetropolitan America

  Why do rural households leave for urban places? And how does this decision affect their economic well-being? Rural places in the United States have higher poverty and unemployment rates and lower levels ...

  Citation × Citation Citation Abstract Copy Title: Out-migration, income and poverty in nonmetropolitan America Author: Marre, Alexander Why do rural households leave for urban places? And how does this decision affect their economic well-being? Rural places in the United States have higher poverty and unemployment rates and lower levels of educational attainment relative to urban places. Does leaving a rural place for a city offer a pathway out of poverty and to greater income? This dissertation examines these questions with data from the Panel Study of Income Dynamics. Four models of household economic outcomes are estimated for three periods: 1979 to 1985, 1985 to 1991, and 1991 to 1997. These models estimate the nonmetropolitan out-migration decision and the following economic outcomes: household poverty, cost-of-housing adjusted household poverty, household income, and cost-of-housing adjusted household income. All four models include an instrumental variable or variables to control for possible endogeneity between the migration decision and economic outcomes. Empirical results indicate that nonmetropolitan out-migration increased poverty risk in the 1979 to 1985 period, yet had no statistically significant effect on any economic outcome during the latter periods. Educational attainment was found to be a significant, in the statistical and economic sense, determinant of economic outcomes. These findings suggest that human capital and other individual and household characteristics explained household poverty risk and income from 1985 to 1997 and that migrating out of nonmetropolitan counties had no effect. The evidence from this study indicates that rural anti-poverty policy should focus on human capital development. It does not support place-based policy. Title: Out-migration, income and poverty in nonmetropolitan America Author: Marre, Alexander Why do rural households leave for urban places? And how does this decision affect their economic well-being? Rural places in the United States have higher poverty and unemployment rates and lower levels of educational attainment relative to urban places. Does leaving a rural place for a city offer a pathway out of poverty and to greater income? This dissertation examines these questions with data from the Panel Study of Income Dynamics. Four models of household economic outcomes are estimated for three periods: 1979 to 1985, 1985 to 1991, and 1991 to 1997. These models estimate the nonmetropolitan out-migration decision and the following economic outcomes: household poverty, cost-of-housing adjusted household poverty, household income, and cost-of-housing adjusted household income. All four models include an instrumental variable or variables to control for possible endogeneity between the migration decision and economic outcomes. Empirical results indicate that nonmetropolitan out-migration increased poverty risk in the 1979 to 1985 period, yet had no statistically significant effect on any economic outcome during the latter periods. Educational attainment was found to be a significant, in the statistical and economic sense, determinant of economic outcomes. These findings suggest that human capital and other individual and household characteristics explained household poverty risk and income from 1985 to 1997 and that migrating out of nonmetropolitan counties had no effect. The evidence from this study indicates that rural anti-poverty policy should focus on human capital development. It does not support place-based policy. Close

• 20. [Article] Passage of juvenile cutthroat trout and steelhead through retrofitted culverts

  Citation × Citation Citation Abstract Copy Title: Passage of juvenile cutthroat trout and steelhead through retrofitted culverts Author: McEnroe, Jeffrey R. Title: Passage of juvenile cutthroat trout and steelhead through retrofitted culverts Author: McEnroe, Jeffrey R. Close