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

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

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

• 382. [Article] Coastal sand dunes of Oregon and Washington

  In Part I the environment of the coastal dunes of Oregon and Washington is analyzed. Most of the substratum is a narrow foreland or terrace, in part submerged, that borders the mountain front. Temperature ...

  Citation × Citation Citation Abstract Copy Title: Coastal sand dunes of Oregon and Washington Author: Cooper, William Skinner, 1884- In Part I the environment of the coastal dunes of Oregon and Washington is analyzed. Most of the substratum is a narrow foreland or terrace, in part submerged, that borders the mountain front. Temperature is relatively low in summer and rarely reaches the freezing point in winter. Winter precipitation is heavy, and there is almost no snow; there is a pronounced deficiency in precipitation in summer. The summer wind is a very constant afternoon sea breeze from north to northwest; winter winds are variable but include frequent southwest gales. Longshore currents are governed by the seasonal winds, moving southward in summer and northward in winter. The regional vegetation is dense, tall conifer forest. The influence of man has been comparatively slight: in prehistoric times the starting of forest fires; in historic time moderate disturbance due to grazing and recent efforts to control the movement of the sand. Part II deals with forms and processes. The simplest combination of elements comprises sand, wind, and water. Interaction of these produces two patterns. In the transverse-ridge pattern the individual unit is a ridge essentially normal to the summer wind and moving with it; it is asymmetric in profile with gentle windward slope and steep leeward slope (slipface). Origin and maintenance of this profile are explained in accordance with principles developed in the field of aerodynamics, and conclusions arrived at deductively are confirmed by slow-motion photography of smoke streams on the dunes. The oblique-ridge pattern occurs only where there is full exposure to both seasonal winds, plenty of space, and plenty of sand. These conditions are met only in Region III (Coos Bay dune sheet). The units are much more massive than the transverse ridges and are essentially stationary. Their trend lies between the means of summer and winter winds. A theoretical explanation of their origin and maintenance is presented, and the oblique ridges and the "longitudinal dunes" of certain desert regions are compared. Neither transverse nor oblique ridge is found in stabilized condition. The factor vegetation added to the other three-sand, wind, and water-promotes stabilization. On a prograding shore, successive beach ridges are quickly captured and fixed, and retain their initial form indefinitely. On a retrograding shore the processes are exceedingly complex and involve repeated stabilization and rejuvenation. Two cases are presented: flat shore, with and without abundant sand supply; stabilized dune masses undergoing erosion. In the latter case, the commoner, development involves the following phases: trough blowout, merging of troughs, reduction to deflation base, and precipitation ridge, which may in time become completely stabilized while still retaining its characteristic form. In places sheltered from one or the other of the seasonal winds, usually the summer wind, giant parabola dunes, which may likewise become fixed by vegetation, develop. Part III is a description of the dune localities of the Oregon-Washington coast and an account of their history. Forty per cent of this coast bears dunes of greater or lesser magnitude. Thirty dune localities are grouped in four regions. Region I includes four localities north of Tillamook Head, Oregon, making a continuous strip 53 km long, that bears the parallel beach-dune-ridge pattern associated with progradation. The forms in Regions II, III, and IV, heterogeneous and complex, are those characteristic of retrograding shores. The two principal stabilized forms are the precipitation ridge and the parabola dune. In Regions II, III, and IV the existing features came into being mainly during the last grand period of sea-level rise, and the seaward portions of massive parabola complexes have been sliced away in varying degree by the advancing sea. The beach-ridge dunes of Region I were formed during the period of comparatively stable sea level, with a probable small net lowering, which followed the maximum of sea advance and has extended to the present. Progradation here during this period, in contrast with almost none south of Tillamook Head, has been possible because of the ample bed load carried to the coast by the Columbia River. South of Tillamook Head there is, in a number of well-distributed localities, evidence of three episodes of advance. The first is represented by the strip of thoroughly stabilized dunes that nearly everywhere forms the inner marginal part of the dune complexes. This episode reached its culmination before the sea had attained its maximum of advance-attested by the slicing away of portions of completely stabilized masses. The second advance for the most part fell short of the first, though in a few places it overpassed the limits of the latter; present condition ranges from complete stabilization to vigorous activity. The third episode is represented by active dunes with open access to the shore. In certain localities there are only an inner strip of stabilized dunes and an outer zone of active dunes. It is assumed that in these the visible effects of the second and third episodes have merged. An earlier cycle of dune development, similar to the modern one in character and extent, is proved by eolian sediments containing altered podzolic soils, which make a minor part of the mantle of unconsolidated materials that lies upon the rock platform of the 30-m terrace. The dunes of which these masses are remnants were formed during the next-to-the-last grand period of submergence. Development of the dunes of Regions II, III, and IV, associated with the grand period of submergence, is assigned to the period of deglaciation that followed the Wisconsin maximum, and mainly to the period of rapid deglaciation that began after the Valders-Mankato advance. The beach-ridge dunes of Region I, on the other hand, have developed in their entirety in the time since sea-level rise was succeeded by stability. By analogy, the earlier cycle of dune development was associated with the waning phase of Illinoian glaciation, and it may be assumed that similar dune cycles were associated with the earlier glaciations of the Pleistocene. Title: Coastal sand dunes of Oregon and Washington Author: Cooper, William Skinner, 1884- In Part I the environment of the coastal dunes of Oregon and Washington is analyzed. Most of the substratum is a narrow foreland or terrace, in part submerged, that borders the mountain front. Temperature is relatively low in summer and rarely reaches the freezing point in winter. Winter precipitation is heavy, and there is almost no snow; there is a pronounced deficiency in precipitation in summer. The summer wind is a very constant afternoon sea breeze from north to northwest; winter winds are variable but include frequent southwest gales. Longshore currents are governed by the seasonal winds, moving southward in summer and northward in winter. The regional vegetation is dense, tall conifer forest. The influence of man has been comparatively slight: in prehistoric times the starting of forest fires; in historic time moderate disturbance due to grazing and recent efforts to control the movement of the sand. Part II deals with forms and processes. The simplest combination of elements comprises sand, wind, and water. Interaction of these produces two patterns. In the transverse-ridge pattern the individual unit is a ridge essentially normal to the summer wind and moving with it; it is asymmetric in profile with gentle windward slope and steep leeward slope (slipface). Origin and maintenance of this profile are explained in accordance with principles developed in the field of aerodynamics, and conclusions arrived at deductively are confirmed by slow-motion photography of smoke streams on the dunes. The oblique-ridge pattern occurs only where there is full exposure to both seasonal winds, plenty of space, and plenty of sand. These conditions are met only in Region III (Coos Bay dune sheet). The units are much more massive than the transverse ridges and are essentially stationary. Their trend lies between the means of summer and winter winds. A theoretical explanation of their origin and maintenance is presented, and the oblique ridges and the "longitudinal dunes" of certain desert regions are compared. Neither transverse nor oblique ridge is found in stabilized condition. The factor vegetation added to the other three-sand, wind, and water-promotes stabilization. On a prograding shore, successive beach ridges are quickly captured and fixed, and retain their initial form indefinitely. On a retrograding shore the processes are exceedingly complex and involve repeated stabilization and rejuvenation. Two cases are presented: flat shore, with and without abundant sand supply; stabilized dune masses undergoing erosion. In the latter case, the commoner, development involves the following phases: trough blowout, merging of troughs, reduction to deflation base, and precipitation ridge, which may in time become completely stabilized while still retaining its characteristic form. In places sheltered from one or the other of the seasonal winds, usually the summer wind, giant parabola dunes, which may likewise become fixed by vegetation, develop. Part III is a description of the dune localities of the Oregon-Washington coast and an account of their history. Forty per cent of this coast bears dunes of greater or lesser magnitude. Thirty dune localities are grouped in four regions. Region I includes four localities north of Tillamook Head, Oregon, making a continuous strip 53 km long, that bears the parallel beach-dune-ridge pattern associated with progradation. The forms in Regions II, III, and IV, heterogeneous and complex, are those characteristic of retrograding shores. The two principal stabilized forms are the precipitation ridge and the parabola dune. In Regions II, III, and IV the existing features came into being mainly during the last grand period of sea-level rise, and the seaward portions of massive parabola complexes have been sliced away in varying degree by the advancing sea. The beach-ridge dunes of Region I were formed during the period of comparatively stable sea level, with a probable small net lowering, which followed the maximum of sea advance and has extended to the present. Progradation here during this period, in contrast with almost none south of Tillamook Head, has been possible because of the ample bed load carried to the coast by the Columbia River. South of Tillamook Head there is, in a number of well-distributed localities, evidence of three episodes of advance. The first is represented by the strip of thoroughly stabilized dunes that nearly everywhere forms the inner marginal part of the dune complexes. This episode reached its culmination before the sea had attained its maximum of advance-attested by the slicing away of portions of completely stabilized masses. The second advance for the most part fell short of the first, though in a few places it overpassed the limits of the latter; present condition ranges from complete stabilization to vigorous activity. The third episode is represented by active dunes with open access to the shore. In certain localities there are only an inner strip of stabilized dunes and an outer zone of active dunes. It is assumed that in these the visible effects of the second and third episodes have merged. An earlier cycle of dune development, similar to the modern one in character and extent, is proved by eolian sediments containing altered podzolic soils, which make a minor part of the mantle of unconsolidated materials that lies upon the rock platform of the 30-m terrace. The dunes of which these masses are remnants were formed during the next-to-the-last grand period of submergence. Development of the dunes of Regions II, III, and IV, associated with the grand period of submergence, is assigned to the period of deglaciation that followed the Wisconsin maximum, and mainly to the period of rapid deglaciation that began after the Valders-Mankato advance. The beach-ridge dunes of Region I, on the other hand, have developed in their entirety in the time since sea-level rise was succeeded by stability. By analogy, the earlier cycle of dune development was associated with the waning phase of Illinoian glaciation, and it may be assumed that similar dune cycles were associated with the earlier glaciations of the Pleistocene. Close

• 383. [Article] The Japanese beef market in a disequilibrium econometrics framework : implications for the U.S. - Japan beef market access agreement

  The success of the U.S. government in persuading Japan to liberalize the beef market is viewed as a relief to the U.S. beef industry. The economic benefit (to the U.S. beef producers!) of the trade liberalization ...

  Citation × Citation Citation Abstract Copy Title: The Japanese beef market in a disequilibrium econometrics framework : implications for the U.S. - Japan beef market access agreement Author: Anteneh, Berhanu The success of the U.S. government in persuading Japan to liberalize the beef market is viewed as a relief to the U.S. beef industry. The economic benefit (to the U.S. beef producers!) of the trade liberalization however is yet to be seen. The size of this benefit is determined, among others, by (a) the net change in Japan's retail price due to the liberalization, (b) the price elasticity of demand for the U.S. beef in Japan, (c) the degree of price rise in the world market, and (d) the export capacity of the domestic sector. Availability of alternative beef sources and the degree of substitutability between the U.S. beef and those alternatives affect factor (b) and factor (d) depends on the extent to which beef and other meat products substitute each other in the domestic market both in production and consumption. Evaluation of the U.S. - Japan Beef Market Access Agreement (BMAA) therefore has become a high policy profile. In the interest of assessing possible policy effects of BMAA, several researchers have attempted to parameterize and quantify the Japanese demand for beef. The fact that this market is (a) semi-isolated from the rest of the world by restrictive import quota, (b) managed domestically by government parastatal, and (c) characterized by multi- and intensely differentiated beef with no parallel historical data has made the choice of economic theory and methodology difficult. While most researchers (Group 1) relied on conventional method [e.g. 55; 125], others (Group 2) [2] contend that managed import market may better be explained by a model of political nature. By assuming the usual competitive market behavior, Group 1 underestimates possible implications of existing market structure for building and estimating conventional econometric models. Group 2, on the other hand, limits itself to normative analysis. Due to the absence of consensus among researchers regarding implications of policy-relevant parameters, the desirability of the BMAA is still an unsettled policy issue. The general purpose of this study has been to generate some further information on Japan's beef market. In pursuant of this objective, an attempt is made to (a) show how significant the beef quality issue is in evaluating that market, (b) test the market equilibrium hypothesis, and (c) upon the acceptance of the alternative (disequilibrium) hypothesis, estimate the structural parameters from a model specified in the light of imperfections in the market. This fills the void in previous studies. Drawing on existing literature, the beef quality categories are shown to have been narrowing and, in fact, converging to the two middle categories, medium and common grades. It is suggested that future market studies may benefit from concentrating on these two grades in assessing competitiveness and substitutability with domestic beef. Understanding the nature of this convergence (i.e whether the shift is attributable to changes in cost or preference structure) may contribute to sound policy making. Based on (a) increased concentration in production and distribution sectors, (b) government intervention in beef and related markets, (c) high degree heterogeneity in beef, and (d) short-run supply inflexibility due to long fattening period and restrictive import policy, the Japanese beef market was hypothesized to have been in disequilibria due to incomplete market information. In testing this hypothesis, two data sets were used -Statistical Yearbook and the Family Income and Expenditure Survey. For reference purposes, they are referred to as Market I and Market II respectively. The equilibrium hypothesis was tested for uniform and upward and downward differential adjustment speeds. The uniform adjustment rate estimated from the reduced form price equation supports the hypothesis in both markets. The structural equations were then adjusted in the light of the imperfections in the market and structural parameters estimated using non-linear three stage least squares. Both upward and downward adjustment speeds in Market I suggest perfect flexibility in prices on annual basis. In Market II, prices are found to have been flexible downward but rigid otherwise. The upward rigidity in prices suggest excess demand. Perfect flexibility in prices on annual basis however may not suggest market equilibrium in a period less than a year. Consumers are found to be more price responsive than in previous studies implying a greater response of the demand for beef imports to changes in prices due to the liberalization than envisaged by previous studies. The demand for beef however is income inelastic suggesting a partial offsetting in the incremental demand for imports. Finally, consumers respond to changes in beef retail prices by consuming less fish and poultry. Title: The Japanese beef market in a disequilibrium econometrics framework : implications for the U.S. - Japan beef market access agreement Author: Anteneh, Berhanu The success of the U.S. government in persuading Japan to liberalize the beef market is viewed as a relief to the U.S. beef industry. The economic benefit (to the U.S. beef producers!) of the trade liberalization however is yet to be seen. The size of this benefit is determined, among others, by (a) the net change in Japan's retail price due to the liberalization, (b) the price elasticity of demand for the U.S. beef in Japan, (c) the degree of price rise in the world market, and (d) the export capacity of the domestic sector. Availability of alternative beef sources and the degree of substitutability between the U.S. beef and those alternatives affect factor (b) and factor (d) depends on the extent to which beef and other meat products substitute each other in the domestic market both in production and consumption. Evaluation of the U.S. - Japan Beef Market Access Agreement (BMAA) therefore has become a high policy profile. In the interest of assessing possible policy effects of BMAA, several researchers have attempted to parameterize and quantify the Japanese demand for beef. The fact that this market is (a) semi-isolated from the rest of the world by restrictive import quota, (b) managed domestically by government parastatal, and (c) characterized by multi- and intensely differentiated beef with no parallel historical data has made the choice of economic theory and methodology difficult. While most researchers (Group 1) relied on conventional method [e.g. 55; 125], others (Group 2) [2] contend that managed import market may better be explained by a model of political nature. By assuming the usual competitive market behavior, Group 1 underestimates possible implications of existing market structure for building and estimating conventional econometric models. Group 2, on the other hand, limits itself to normative analysis. Due to the absence of consensus among researchers regarding implications of policy-relevant parameters, the desirability of the BMAA is still an unsettled policy issue. The general purpose of this study has been to generate some further information on Japan's beef market. In pursuant of this objective, an attempt is made to (a) show how significant the beef quality issue is in evaluating that market, (b) test the market equilibrium hypothesis, and (c) upon the acceptance of the alternative (disequilibrium) hypothesis, estimate the structural parameters from a model specified in the light of imperfections in the market. This fills the void in previous studies. Drawing on existing literature, the beef quality categories are shown to have been narrowing and, in fact, converging to the two middle categories, medium and common grades. It is suggested that future market studies may benefit from concentrating on these two grades in assessing competitiveness and substitutability with domestic beef. Understanding the nature of this convergence (i.e whether the shift is attributable to changes in cost or preference structure) may contribute to sound policy making. Based on (a) increased concentration in production and distribution sectors, (b) government intervention in beef and related markets, (c) high degree heterogeneity in beef, and (d) short-run supply inflexibility due to long fattening period and restrictive import policy, the Japanese beef market was hypothesized to have been in disequilibria due to incomplete market information. In testing this hypothesis, two data sets were used -Statistical Yearbook and the Family Income and Expenditure Survey. For reference purposes, they are referred to as Market I and Market II respectively. The equilibrium hypothesis was tested for uniform and upward and downward differential adjustment speeds. The uniform adjustment rate estimated from the reduced form price equation supports the hypothesis in both markets. The structural equations were then adjusted in the light of the imperfections in the market and structural parameters estimated using non-linear three stage least squares. Both upward and downward adjustment speeds in Market I suggest perfect flexibility in prices on annual basis. In Market II, prices are found to have been flexible downward but rigid otherwise. The upward rigidity in prices suggest excess demand. Perfect flexibility in prices on annual basis however may not suggest market equilibrium in a period less than a year. Consumers are found to be more price responsive than in previous studies implying a greater response of the demand for beef imports to changes in prices due to the liberalization than envisaged by previous studies. The demand for beef however is income inelastic suggesting a partial offsetting in the incremental demand for imports. Finally, consumers respond to changes in beef retail prices by consuming less fish and poultry. Close

• 384. [Article] White-breasted nuthatch density and nesting ecology in oak woodlands of the Willamette Valley, Oregon

  Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) ...

  Citation × Citation Citation Abstract Copy Title: White-breasted nuthatch density and nesting ecology in oak woodlands of the Willamette Valley, Oregon Author: Viste-Sparkman, Karen Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may be limited by the availability of existing cavities for nesting and roosting. Oak vegetation in the Willamette Valley has changed since European-American settlement times from vast areas of open oak savanna to isolated closed-canopy stands separated by agricultural fields. We examined nuthatch density, nest cavity selection, and nest success in relation to oak woodland structure and landscape context. We conducted point transect surveys in 3 strata: woodland interiors, large woodland edges, and small woodlands. We located and monitored nuthatch nests and sampled vegetation at nest locations and matching random locations around each nest. Woodland structure and edge density were measured at a 178-m radius (home range) scale, and landscape context was measured using vegetation cover within a 1-km radius around point transects and nests. We used program DISTANCE to fit detection functions and calculate nuthatch densities. We used conditional logistic regression to compare nest locations with random locations, and analyzed nest success with Mayfield logistic regression. White-breasted nuthatch density was significantly higher in small woodlands than in edges of large woodlands, which had higher nuthatch density than woodland interiors. Density of nuthatches increased with a combination of oak cover within a 1-km radius of the point, edge density within a 178-m radius, and number of oak trees >50 cm diameter at breast height (dbh) within a 100-m radius. Nest cavities were situated in oak trees containing more cavities than random oak trees that had cavities, and oak trees used as nest trees had a larger dbh than oak trees within random plots. Local woodland structure at nest locations was characterized by larger trees, measured by greater mean dbh, canopy cover, and basal area of oaks than random locations within the home range. Nest success in natural cavities was 71% and was not predicted by attributes of nest cavities, nest trees, local woodland structure at nests, woodland structure at the home range scale, or landscape context. These results suggest that the most suitable habitat for white-breasted nuthatches in the Willamette Valley includes oak woodlands in close proximity to one another with a high proportion of edge and mature oak trees. Managers should preserve trees containing cavities and large oak trees whenever possible. Thinning of small oaks and removal of conifers in oak woodlands to create more open, savanna-like conditions may also promote the development of larger oaks with more spreading branches, providing more opportunities for cavities to form and more foraging surface area for nuthatches. Title: White-breasted nuthatch density and nesting ecology in oak woodlands of the Willamette Valley, Oregon Author: Viste-Sparkman, Karen Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may be limited by the availability of existing cavities for nesting and roosting. Oak vegetation in the Willamette Valley has changed since European-American settlement times from vast areas of open oak savanna to isolated closed-canopy stands separated by agricultural fields. We examined nuthatch density, nest cavity selection, and nest success in relation to oak woodland structure and landscape context. We conducted point transect surveys in 3 strata: woodland interiors, large woodland edges, and small woodlands. We located and monitored nuthatch nests and sampled vegetation at nest locations and matching random locations around each nest. Woodland structure and edge density were measured at a 178-m radius (home range) scale, and landscape context was measured using vegetation cover within a 1-km radius around point transects and nests. We used program DISTANCE to fit detection functions and calculate nuthatch densities. We used conditional logistic regression to compare nest locations with random locations, and analyzed nest success with Mayfield logistic regression. White-breasted nuthatch density was significantly higher in small woodlands than in edges of large woodlands, which had higher nuthatch density than woodland interiors. Density of nuthatches increased with a combination of oak cover within a 1-km radius of the point, edge density within a 178-m radius, and number of oak trees >50 cm diameter at breast height (dbh) within a 100-m radius. Nest cavities were situated in oak trees containing more cavities than random oak trees that had cavities, and oak trees used as nest trees had a larger dbh than oak trees within random plots. Local woodland structure at nest locations was characterized by larger trees, measured by greater mean dbh, canopy cover, and basal area of oaks than random locations within the home range. Nest success in natural cavities was 71% and was not predicted by attributes of nest cavities, nest trees, local woodland structure at nests, woodland structure at the home range scale, or landscape context. These results suggest that the most suitable habitat for white-breasted nuthatches in the Willamette Valley includes oak woodlands in close proximity to one another with a high proportion of edge and mature oak trees. Managers should preserve trees containing cavities and large oak trees whenever possible. Thinning of small oaks and removal of conifers in oak woodlands to create more open, savanna-like conditions may also promote the development of larger oaks with more spreading branches, providing more opportunities for cavities to form and more foraging surface area for nuthatches. Close

• 385. [Article] An investigation into modeling snow cover elements at Crater Lake National Park and surrounding environs as an improved "ground truth" method for satellite snow observations

  Streamflow forecasts are essential to the optimal operation of hydroelectric and irrigation reservoirs in the Pacific Northwest. Satellite snow cover observations would aid in these streamflow forecasts by ...

  Citation × Citation Citation Abstract Copy Title: An investigation into modeling snow cover elements at Crater Lake National Park and surrounding environs as an improved "ground truth" method for satellite snow observations Author: Hamilton, William L. Streamflow forecasts are essential to the optimal operation of hydroelectric and irrigation reservoirs in the Pacific Northwest. Satellite snow cover observations would aid in these streamflow forecasts by providing snow cover data at regular time intervals. Unfortunately, satellite capability to remotely sense mountain snow cover conditions is indeterminate due to lack of "ground truth." This study focuses on the development of a mountain snow cover model capable of generating snow cover data at a scale useful as "ground truth" for operational satellite snow cover observations. The study area used to develop the snow cover model was Crater Lake National Park and its surrounding environs. Both the physiography (topography and vegetation) and snow climate of the study area were analyzed and found to be quite dynamic. In order to take into account the affects of the dynamic snow climate and physiography upon snow cover conditions, multiple regression analysis was used to create the Crater Lake Snow Model. Forty-five snow core sites were located within the study area. Snow depth and snow water equivalent values were recorded at each site. Eighteen sites located within Crater Lake National Park were sampled on a weekly basis for the 1977-1978 snow year. An additional 16 sites were sampled at high elevations in the Park on a weekly basis from April through June, 1978. The remaining 11 sites comprised the historical snow core data set collected by Soil Conservation Service (S.C.S.) on a monthly basis, January through June, 1948 through 1978. These data sets were statistically reduced using the quasi-constant ratio theory to synthesize values for missing data to temporally unify the data sets. Also the physiographic elements of slope, aspect, elevation, percentage of forest canopy cover, and regional aspect were recorded for each snow core site. The physiographic elements (independent variables) were regressed against the snow core data (dependent variables) to produce snow model equations. Three different Temporal-Spatial Situations (T.S.S. 1, 2, 3) of data were entered into regression analysis. T.S.S. 1 and 2 models were generated from the 11 S.C.S. snow core sites, T.S.S. 1 from 1978 data and T.S.S. 2 for 1948 -1978 data. The T.S.S. 3 model was generated from the 45 snow core site data for 1978. Using the theory of the quasiconstant ratio it was possible to combine the T.S.S. 1, 2, and 3 sets of regression equations to produce a T.S.S. 4 snow model ( a model based upon the 45 sites for the 1948-1978 snow seasons). Subsequently the T.S.S. 1 and 2 snow models were utilized with this derived T.S.S. 4 snow model to produce T.S.S. 3 snow cover models for any month of any year for the 1948 through 1978 period. Validity testing of the model indicates that it has an average error of ± 15.7" for modeled snow depth values and ± 8.2" for modeled snow water equivalent values. The Crater Lake Snow Model has a combined spatial, annual, and long term resolution unequaled in previous snow cover models. The Model's combined high resolving properties give it capabilities of generating mountain snow cover "ground truth." Current studies are being conducted to couple dynamic snow meteorology and LANDSAT digital data to the Model to increase its accuracy and reduce its dependency on snow core data. Also, output of the Model can be used for studies on snow cover affect upon wildlife movement and survival and the determination of source regions of relative runoff from snow melt. Title: An investigation into modeling snow cover elements at Crater Lake National Park and surrounding environs as an improved "ground truth" method for satellite snow observations Author: Hamilton, William L. Streamflow forecasts are essential to the optimal operation of hydroelectric and irrigation reservoirs in the Pacific Northwest. Satellite snow cover observations would aid in these streamflow forecasts by providing snow cover data at regular time intervals. Unfortunately, satellite capability to remotely sense mountain snow cover conditions is indeterminate due to lack of "ground truth." This study focuses on the development of a mountain snow cover model capable of generating snow cover data at a scale useful as "ground truth" for operational satellite snow cover observations. The study area used to develop the snow cover model was Crater Lake National Park and its surrounding environs. Both the physiography (topography and vegetation) and snow climate of the study area were analyzed and found to be quite dynamic. In order to take into account the affects of the dynamic snow climate and physiography upon snow cover conditions, multiple regression analysis was used to create the Crater Lake Snow Model. Forty-five snow core sites were located within the study area. Snow depth and snow water equivalent values were recorded at each site. Eighteen sites located within Crater Lake National Park were sampled on a weekly basis for the 1977-1978 snow year. An additional 16 sites were sampled at high elevations in the Park on a weekly basis from April through June, 1978. The remaining 11 sites comprised the historical snow core data set collected by Soil Conservation Service (S.C.S.) on a monthly basis, January through June, 1948 through 1978. These data sets were statistically reduced using the quasi-constant ratio theory to synthesize values for missing data to temporally unify the data sets. Also the physiographic elements of slope, aspect, elevation, percentage of forest canopy cover, and regional aspect were recorded for each snow core site. The physiographic elements (independent variables) were regressed against the snow core data (dependent variables) to produce snow model equations. Three different Temporal-Spatial Situations (T.S.S. 1, 2, 3) of data were entered into regression analysis. T.S.S. 1 and 2 models were generated from the 11 S.C.S. snow core sites, T.S.S. 1 from 1978 data and T.S.S. 2 for 1948 -1978 data. The T.S.S. 3 model was generated from the 45 snow core site data for 1978. Using the theory of the quasiconstant ratio it was possible to combine the T.S.S. 1, 2, and 3 sets of regression equations to produce a T.S.S. 4 snow model ( a model based upon the 45 sites for the 1948-1978 snow seasons). Subsequently the T.S.S. 1 and 2 snow models were utilized with this derived T.S.S. 4 snow model to produce T.S.S. 3 snow cover models for any month of any year for the 1948 through 1978 period. Validity testing of the model indicates that it has an average error of ± 15.7" for modeled snow depth values and ± 8.2" for modeled snow water equivalent values. The Crater Lake Snow Model has a combined spatial, annual, and long term resolution unequaled in previous snow cover models. The Model's combined high resolving properties give it capabilities of generating mountain snow cover "ground truth." Current studies are being conducted to couple dynamic snow meteorology and LANDSAT digital data to the Model to increase its accuracy and reduce its dependency on snow core data. Also, output of the Model can be used for studies on snow cover affect upon wildlife movement and survival and the determination of source regions of relative runoff from snow melt. Close

• 386. [Article] Emergency contraceptive pills and college women : factors influencing intention and use

  Approximately half of the 6.4 million pregnancies occurring each year in the United States are unintended (Finer & Henshaw, 2006). Unintended pregnancies, defined as pregnancies not wanted at the time ...

  Citation × Citation Citation Abstract Copy Title: Emergency contraceptive pills and college women : factors influencing intention and use Author: Nelson, Heather A. Approximately half of the 6.4 million pregnancies occurring each year in the United States are unintended (Finer & Henshaw, 2006). Unintended pregnancies, defined as pregnancies not wanted at the time conception occurs, regardless of contraceptive use (Chandra, Martinez, Mosher, Abma, & Jones, 2005) can have serious repercussions on women, children, and society. For decades, women facing the possibility of an unintended pregnancy following unprotected intercourse, birth control method failure, or sexual assault, have had no choices outside of abortion. Since 1997 however, another option has become available to American women making unintended pregnancy decisions – emergency contraceptive pills (ECPs). Research has indicated that widespread use of ECPs has the potential to prevent 1.5 million of the approximate 3 million unintended pregnancies occurring each year in the US, including as many as 700,000 pregnancies that now result in abortion (Trussell, Stewart, Guest, & Hatcher, 1992). Although 84% of American women have heard of ECPs, only 6% claim to have ever used them (Hoff, Miller, Barefoot, & Greene, 2003). Despite their effectiveness and the public’s awareness of them, ECPs still remain underutilized in many high-risk populations. Explanations for this discrepancy are not readily available. In particular, young adult women attending college are at risk for unintended pregnancy yet we know little about their relationship with ECPs. Although extensive ECP use could have a profound effect on unintended pregnancy rates, we have limited information about the factors that influence a woman's decision to use ECPs. Furthermore, with the US Food and Drug Administration's approval of behind the counter status for the emergency contraceptive Plan B on August 24, 2006, one of the last major external hurdles for women accessing emergency contraceptive pills appears to have been removed. However, it is unknown whether prescription-free availability will be the final factor in women's predisposition to use ECPs or if other intrinsic factors, may in fact, override use. The purpose of this study was to determine the nature and extent of college women's knowledge, self-efficacy, attitudes, perceived social norms, and use related to emergency contraceptive pills. Additional goals included: using a conceptual framework to determine which social and behavioral constructs suggested by the contraceptive literature best predict intention to use ECPs and ECP use. Data were collected via an online survey designed by the lead author. A sample of 4,219 female students was drawn from a directory list of students enrolled at Oregon State University during the Spring Quarter of 2004. A total of 1718 women returned usable questionnaires. Key findings were that the majority of sexually active participants (68%, n = 871) had experienced a pregnancy scare in the past yet only 28.3% (n = 362) had ever used ECPs. Further, women had insufficient knowledge about ECPs in order to make informed decisions. Male partners were the most influential social reference in ECP decision-making. Although prescription-free access to ECPs is an historical milestone for reproductive health in the US, this policy change may not be the final step in ensuring that women access and use ECPs when they need them. Intrinsic factors including: knowledge that ECPs prevent pregnancy by interfering with ovulation, knowledge that ECPs are not a form of abortion, and confidence in accessing ECPs in time if needed seem to influence ECP use. In order for ECPs to impact unintended pregnancy rates to the extent research has demonstrated, strategies addressing these internal factors are warranted and must target both women and men. Title: Emergency contraceptive pills and college women : factors influencing intention and use Author: Nelson, Heather A. Approximately half of the 6.4 million pregnancies occurring each year in the United States are unintended (Finer & Henshaw, 2006). Unintended pregnancies, defined as pregnancies not wanted at the time conception occurs, regardless of contraceptive use (Chandra, Martinez, Mosher, Abma, & Jones, 2005) can have serious repercussions on women, children, and society. For decades, women facing the possibility of an unintended pregnancy following unprotected intercourse, birth control method failure, or sexual assault, have had no choices outside of abortion. Since 1997 however, another option has become available to American women making unintended pregnancy decisions – emergency contraceptive pills (ECPs). Research has indicated that widespread use of ECPs has the potential to prevent 1.5 million of the approximate 3 million unintended pregnancies occurring each year in the US, including as many as 700,000 pregnancies that now result in abortion (Trussell, Stewart, Guest, & Hatcher, 1992). Although 84% of American women have heard of ECPs, only 6% claim to have ever used them (Hoff, Miller, Barefoot, & Greene, 2003). Despite their effectiveness and the public’s awareness of them, ECPs still remain underutilized in many high-risk populations. Explanations for this discrepancy are not readily available. In particular, young adult women attending college are at risk for unintended pregnancy yet we know little about their relationship with ECPs. Although extensive ECP use could have a profound effect on unintended pregnancy rates, we have limited information about the factors that influence a woman's decision to use ECPs. Furthermore, with the US Food and Drug Administration's approval of behind the counter status for the emergency contraceptive Plan B on August 24, 2006, one of the last major external hurdles for women accessing emergency contraceptive pills appears to have been removed. However, it is unknown whether prescription-free availability will be the final factor in women's predisposition to use ECPs or if other intrinsic factors, may in fact, override use. The purpose of this study was to determine the nature and extent of college women's knowledge, self-efficacy, attitudes, perceived social norms, and use related to emergency contraceptive pills. Additional goals included: using a conceptual framework to determine which social and behavioral constructs suggested by the contraceptive literature best predict intention to use ECPs and ECP use. Data were collected via an online survey designed by the lead author. A sample of 4,219 female students was drawn from a directory list of students enrolled at Oregon State University during the Spring Quarter of 2004. A total of 1718 women returned usable questionnaires. Key findings were that the majority of sexually active participants (68%, n = 871) had experienced a pregnancy scare in the past yet only 28.3% (n = 362) had ever used ECPs. Further, women had insufficient knowledge about ECPs in order to make informed decisions. Male partners were the most influential social reference in ECP decision-making. Although prescription-free access to ECPs is an historical milestone for reproductive health in the US, this policy change may not be the final step in ensuring that women access and use ECPs when they need them. Intrinsic factors including: knowledge that ECPs prevent pregnancy by interfering with ovulation, knowledge that ECPs are not a form of abortion, and confidence in accessing ECPs in time if needed seem to influence ECP use. In order for ECPs to impact unintended pregnancy rates to the extent research has demonstrated, strategies addressing these internal factors are warranted and must target both women and men. Close

• 387. [Article] Distribution, Abundance, and Settlement of Slope-spawning Flatfish during Early Life Stages in the Eastern Bering Sea

  Changes in environmental conditions in marine ecosystems could directly or indirectly influence distribution, abundance, settlement, and size at settlement of flatfish. Understanding species-specific and ...

  Citation × Citation Citation Abstract Copy Title: Distribution, Abundance, and Settlement of Slope-spawning Flatfish during Early Life Stages in the Eastern Bering Sea Author: Sohn, Dongwha Changes in environmental conditions in marine ecosystems could directly or indirectly influence distribution, abundance, settlement, and size at settlement of flatfish. Understanding species-specific and age-specific responses to environmental variability is important for managing commercially important flatfish stocks. Slope-spawning flatfish whose offspring rely on extensive drift from the slope (spawning) to the shelf (settlement) and which require specific habitat for settlement could be especially vulnerable to environmental variability. Arrowtooth flounder (ATF; Atheresthes stomias), Greenland halibut (GH; Reinhardtius hippoglossoides), and Pacific halibut (PH; Hippoglossus stenolepis) are commercially and ecologically important slope-spawning flatfish species in the eastern Bering Sea (EBS), which has experienced fluctuating warm and cold periods since 2000. Although the three species share many attributes, their population trajectories have fluctuated differently. This difference could result from contrasting responses to environmental variability during early life history. To understand how physical variability of the Bering Sea can differentially affect flatfish ecology from pre-settlement to post-settlement phases, I used a combination of field data, biophysical modeling, and statistical modeling to characterize early life stage attributes (chapter 2), settlement success (chapter 3), and size, abundance, and distribution at settlement (age-0) and age-1 (chapter 4). Based on historical ichthyoplankton survey data for GH and PH, I found that there were species-specific differences in the spatial distribution (vertically and horizontally) and juvenile nursery areas between the two species during early life stages in the EBS. Specifically, I found that PH larvae abruptly move to shallower water as they grow, and cross onto the shelf earlier than GH. This ontogenetic movement has the benefit of allowing PH larvae to take advantage of on-shelf transport to reach their settlement locations. However, an early transition from the slope to the shelf may not equally benefit GH, whose settlement locations are further from the spawning ground. Using a bio-physical modeling approach parameterized on the field data summarized in chapter 2, I found that species-specific variability of early life attributes causes interannual and species-specific variability of GH and PH settlement success in the EBS. GH settlement increased with increasing along-shelf (northwestward) flow whereas PH settlement decreased. GH that spawned in November and December were highly successful at settling while PH settlement was most successful when they spawned in January and February. Furthermore, GH settlement is affected by temperature dependence of pelagic larval duration, but not PH, indicating a strong resilience of PH to temperature induced variations in development and dispersal duration. Using otolith microstructure analysis, I found that variations in size at settlement for ATF are significantly correlated with latitude of sampling location. For GH, their size at settlement is associated with bottom water temperature and sea ice extent. Especially, sea ice coverage has a strong negative correlation with on-shelf winds, which drive along-shelf Ekman transport to southeast impacting dispersal pathways and duration. Size at settlement for ATF increased with increasing latitude of sampling location, which could be impacted by currents. For GH, size at settlement decreased with decreasing bottom water temperature and increasing sea ice extent. Also, my results showed that settlement habitat increases for GH in cold years whereas that of ATF increases in warm years. The bottom temperature of age-0 habitat for both ATF and GH affected on their age-1 abundance; GH age-1 abundance increased with decreasing bottom temperature of age-0 habitat, but no clear directionality was found for ATF. The findings from this study have implications for understanding settlement success and recruitment of slope-spawning flatfish in the EBS. In most cold years when along-shelf flow is generally strong, the level of larval supply of GH to their settlement areas is higher than in warm years. Size at settlement for GH decreased in cold years. The larger amount of suitable habitat for settlement and post-settlement stages could result in lower competition and less predation in comparison to warm years. In support of this hypothesis, I found greater age-1 abundance in cold years, indicating size at settlement in GH may not be critical compared to suitability of habitat features and larval supply to settlement grounds. On the other hand, in cold years with strong along-shelf transport to northwest, PH (or ATF), which settle in the southern part of the EBS, have lower numbers of successful settlers. Size at settlement for ATF increased in cold years, and I assumed that size at settlement for PH may have similar patterns. The amount of suitable habitat after settlement would be smaller, resulting in lower recruitment due to increased competition for limited resources. By studying how physical factors and their variability influence these three flatfish during early life stages, this study provides valuable insight into the response of flatfish stocks to past and future climate changes in the eastern Bering Sea – a system that is especially vulnerable to warming. Title: Distribution, Abundance, and Settlement of Slope-spawning Flatfish during Early Life Stages in the Eastern Bering Sea Author: Sohn, Dongwha Changes in environmental conditions in marine ecosystems could directly or indirectly influence distribution, abundance, settlement, and size at settlement of flatfish. Understanding species-specific and age-specific responses to environmental variability is important for managing commercially important flatfish stocks. Slope-spawning flatfish whose offspring rely on extensive drift from the slope (spawning) to the shelf (settlement) and which require specific habitat for settlement could be especially vulnerable to environmental variability. Arrowtooth flounder (ATF; Atheresthes stomias), Greenland halibut (GH; Reinhardtius hippoglossoides), and Pacific halibut (PH; Hippoglossus stenolepis) are commercially and ecologically important slope-spawning flatfish species in the eastern Bering Sea (EBS), which has experienced fluctuating warm and cold periods since 2000. Although the three species share many attributes, their population trajectories have fluctuated differently. This difference could result from contrasting responses to environmental variability during early life history. To understand how physical variability of the Bering Sea can differentially affect flatfish ecology from pre-settlement to post-settlement phases, I used a combination of field data, biophysical modeling, and statistical modeling to characterize early life stage attributes (chapter 2), settlement success (chapter 3), and size, abundance, and distribution at settlement (age-0) and age-1 (chapter 4). Based on historical ichthyoplankton survey data for GH and PH, I found that there were species-specific differences in the spatial distribution (vertically and horizontally) and juvenile nursery areas between the two species during early life stages in the EBS. Specifically, I found that PH larvae abruptly move to shallower water as they grow, and cross onto the shelf earlier than GH. This ontogenetic movement has the benefit of allowing PH larvae to take advantage of on-shelf transport to reach their settlement locations. However, an early transition from the slope to the shelf may not equally benefit GH, whose settlement locations are further from the spawning ground. Using a bio-physical modeling approach parameterized on the field data summarized in chapter 2, I found that species-specific variability of early life attributes causes interannual and species-specific variability of GH and PH settlement success in the EBS. GH settlement increased with increasing along-shelf (northwestward) flow whereas PH settlement decreased. GH that spawned in November and December were highly successful at settling while PH settlement was most successful when they spawned in January and February. Furthermore, GH settlement is affected by temperature dependence of pelagic larval duration, but not PH, indicating a strong resilience of PH to temperature induced variations in development and dispersal duration. Using otolith microstructure analysis, I found that variations in size at settlement for ATF are significantly correlated with latitude of sampling location. For GH, their size at settlement is associated with bottom water temperature and sea ice extent. Especially, sea ice coverage has a strong negative correlation with on-shelf winds, which drive along-shelf Ekman transport to southeast impacting dispersal pathways and duration. Size at settlement for ATF increased with increasing latitude of sampling location, which could be impacted by currents. For GH, size at settlement decreased with decreasing bottom water temperature and increasing sea ice extent. Also, my results showed that settlement habitat increases for GH in cold years whereas that of ATF increases in warm years. The bottom temperature of age-0 habitat for both ATF and GH affected on their age-1 abundance; GH age-1 abundance increased with decreasing bottom temperature of age-0 habitat, but no clear directionality was found for ATF. The findings from this study have implications for understanding settlement success and recruitment of slope-spawning flatfish in the EBS. In most cold years when along-shelf flow is generally strong, the level of larval supply of GH to their settlement areas is higher than in warm years. Size at settlement for GH decreased in cold years. The larger amount of suitable habitat for settlement and post-settlement stages could result in lower competition and less predation in comparison to warm years. In support of this hypothesis, I found greater age-1 abundance in cold years, indicating size at settlement in GH may not be critical compared to suitability of habitat features and larval supply to settlement grounds. On the other hand, in cold years with strong along-shelf transport to northwest, PH (or ATF), which settle in the southern part of the EBS, have lower numbers of successful settlers. Size at settlement for ATF increased in cold years, and I assumed that size at settlement for PH may have similar patterns. The amount of suitable habitat after settlement would be smaller, resulting in lower recruitment due to increased competition for limited resources. By studying how physical factors and their variability influence these three flatfish during early life stages, this study provides valuable insight into the response of flatfish stocks to past and future climate changes in the eastern Bering Sea – a system that is especially vulnerable to warming. Close