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• 211. [Article] Phylogeography and population genetic structure of double-crested cormorants (Phalacrocorax auritus)

  The Double-crested Cormorant (Phalacrocorax auritus) is a widespread, colonial, North American waterbird with bicoastal and inland distributions. Four subspecies have been described within North America ...

  Citation × Citation Citation Abstract Copy Title: Phylogeography and population genetic structure of double-crested cormorants (Phalacrocorax auritus) Author: Mercer, Dacey M. The Double-crested Cormorant (Phalacrocorax auritus) is a widespread, colonial, North American waterbird with bicoastal and inland distributions. Four subspecies have been described within North America corresponding to five geographic breeding regions: Interior and North Atlantic cormorants (P. a. auritus); Southeastern cormorants (P. a. floridanus); Alaskan cormorants (P. a. cincinnatus); and Pacific cormorants (P. a. albociliatus). Management strategies vary widely across the species' range according to local perceptions rather than relative population status. An understanding of population genetic structure is necessary for delineating appropriate management units. We examined the genetic structure of Double-crested Cormorants across their range in the United States and Canada to quantify variation within and among breeding sites and to assess the status of traditional geographically defined subspecies. Sequences (700bp) from domains I and II of the mitochondrial control region were analyzed for 234 Double-crested Cormorants from 23 breeding sites. Variation was also examined at 8 microsatellite loci for 395 cormorants from the same 23 breeding sites. The mtDNA and microsatellite data provided strong evidence that the Alaskan subspecies is genetically divergent from other populations in North America (net sequence divergence = 6.72%; ΦST for mtDNA control region = 0.738; FST for microsatellite loci = 0.05). Our data also suggested strong genetic divergence in the southwestern U.S.; southern California may represent a zone of introgression resulting from a northward expansion of a unique lineage from the species' range in northwestern Mexico. In contrast, there was little support for recognition of subspecies within the conterminous U.S. and Canada, outside of Alaska. Rather than genetically distinct regions corresponding to the putative subspecies, we observed a distribution of genetic variation consistent with a pattern of gradual isolation by distance. This pattern implies that genetic differences across the range are due to geographic distance rather than discrete subspecific breaks. Although three of the four subspecies were not genetically distinct, potential demographic separation, habitat differences, and recent declines at some colonies within the regions, suggests that the Pacific and possibly the North Atlantic breeding regions may still warrant consideration as distinct populations. This thesis provides the first species-wide assessment of the phylogeography and population genetic structure of the Double-crested Cormorant. It further resulted in the first microsatellite markers developed specifically for a North American pelecaniform. The mitochondrial and microsatellite data provide a comprehensive assessment of the four putative subspecies described for the species. Given the highly varying conservation status of Double-crested Cormorants throughout their range, results of this study provide guidance for conservation and management practices on their behalf in North America. Title: Phylogeography and population genetic structure of double-crested cormorants (Phalacrocorax auritus) Author: Mercer, Dacey M. The Double-crested Cormorant (Phalacrocorax auritus) is a widespread, colonial, North American waterbird with bicoastal and inland distributions. Four subspecies have been described within North America corresponding to five geographic breeding regions: Interior and North Atlantic cormorants (P. a. auritus); Southeastern cormorants (P. a. floridanus); Alaskan cormorants (P. a. cincinnatus); and Pacific cormorants (P. a. albociliatus). Management strategies vary widely across the species' range according to local perceptions rather than relative population status. An understanding of population genetic structure is necessary for delineating appropriate management units. We examined the genetic structure of Double-crested Cormorants across their range in the United States and Canada to quantify variation within and among breeding sites and to assess the status of traditional geographically defined subspecies. Sequences (700bp) from domains I and II of the mitochondrial control region were analyzed for 234 Double-crested Cormorants from 23 breeding sites. Variation was also examined at 8 microsatellite loci for 395 cormorants from the same 23 breeding sites. The mtDNA and microsatellite data provided strong evidence that the Alaskan subspecies is genetically divergent from other populations in North America (net sequence divergence = 6.72%; ΦST for mtDNA control region = 0.738; FST for microsatellite loci = 0.05). Our data also suggested strong genetic divergence in the southwestern U.S.; southern California may represent a zone of introgression resulting from a northward expansion of a unique lineage from the species' range in northwestern Mexico. In contrast, there was little support for recognition of subspecies within the conterminous U.S. and Canada, outside of Alaska. Rather than genetically distinct regions corresponding to the putative subspecies, we observed a distribution of genetic variation consistent with a pattern of gradual isolation by distance. This pattern implies that genetic differences across the range are due to geographic distance rather than discrete subspecific breaks. Although three of the four subspecies were not genetically distinct, potential demographic separation, habitat differences, and recent declines at some colonies within the regions, suggests that the Pacific and possibly the North Atlantic breeding regions may still warrant consideration as distinct populations. This thesis provides the first species-wide assessment of the phylogeography and population genetic structure of the Double-crested Cormorant. It further resulted in the first microsatellite markers developed specifically for a North American pelecaniform. The mitochondrial and microsatellite data provide a comprehensive assessment of the four putative subspecies described for the species. Given the highly varying conservation status of Double-crested Cormorants throughout their range, results of this study provide guidance for conservation and management practices on their behalf in North America. Close

• 212. [Article] Traditional ecological knowledge to develop and maintain fire regimes in northwestern California, Klamath-Siskiyou bioregion : management and restoration of culturally significant habitats

  The use of Native American fire regimes evolved in the Klamath-Siskiyou bioregion over millennia. A mixture of Native American and Euro-American sociocultural management has developed from adaptations ...

  Citation × Citation Citation Abstract Copy Title: Traditional ecological knowledge to develop and maintain fire regimes in northwestern California, Klamath-Siskiyou bioregion : management and restoration of culturally significant habitats Author: Lake, Frank K. The use of Native American fire regimes evolved in the Klamath-Siskiyou bioregion over millennia. A mixture of Native American and Euro-American sociocultural management has developed from adaptations to climate, topography, ecological processes, and land use practices. This research incorporates Traditional Ecological Knowledge (TEK) to partially examine the role of tribal fire uses and ethnobotany. Research methods use an interdisciplinary approach to characterize fuels and fire management issues in culturally significant riparian and terrestrial habitats. Tribal fuels and fire management practices were investigated. Understanding past tribal fire management systems is needed to place contemporary Native American fuels and fire management issues in to context for government agencies and private interest that have altered tribal opportunities to continue fire uses. This study examined fire effects on sandbar willow (Salix exigua) in valley riparian zones along the lower mid-Klamath River. Prescribed fire was used to induce sprouting of sandbar willow and reduce insect populations to improve basket material quantity and quality. Results indicate that flooding had greater affects on the structure, composition, and abundance of vegetation and fuels than prescribed fire. A second experiment to compare the effect of propane burning and pruning sandbar willow indicated that propane burning was less effective than pruning to improve stem morphology for basket weaving. Consultation with tribal basket weavers and research of the proportion of useable willow shoots, amount of insect damage and the relationship of stem diameter and length revealed these attributes were important criteria for determining usability for weaving. This research also included other basketry plants. TEK is used to better understand fire effects on culturally significant resources and the consequences of fire suppression on terrestrial and riparian habitats. The mechanisms of how fire suppression impacts tribes, resources and tribal land uses are presented. Recommendations are presented for additional research to improve collaboration with tribes, tribal organizations and communities based on contemporary tribal values and priorities for fuels and fire management. Title: Traditional ecological knowledge to develop and maintain fire regimes in northwestern California, Klamath-Siskiyou bioregion : management and restoration of culturally significant habitats Author: Lake, Frank K. The use of Native American fire regimes evolved in the Klamath-Siskiyou bioregion over millennia. A mixture of Native American and Euro-American sociocultural management has developed from adaptations to climate, topography, ecological processes, and land use practices. This research incorporates Traditional Ecological Knowledge (TEK) to partially examine the role of tribal fire uses and ethnobotany. Research methods use an interdisciplinary approach to characterize fuels and fire management issues in culturally significant riparian and terrestrial habitats. Tribal fuels and fire management practices were investigated. Understanding past tribal fire management systems is needed to place contemporary Native American fuels and fire management issues in to context for government agencies and private interest that have altered tribal opportunities to continue fire uses. This study examined fire effects on sandbar willow (Salix exigua) in valley riparian zones along the lower mid-Klamath River. Prescribed fire was used to induce sprouting of sandbar willow and reduce insect populations to improve basket material quantity and quality. Results indicate that flooding had greater affects on the structure, composition, and abundance of vegetation and fuels than prescribed fire. A second experiment to compare the effect of propane burning and pruning sandbar willow indicated that propane burning was less effective than pruning to improve stem morphology for basket weaving. Consultation with tribal basket weavers and research of the proportion of useable willow shoots, amount of insect damage and the relationship of stem diameter and length revealed these attributes were important criteria for determining usability for weaving. This research also included other basketry plants. TEK is used to better understand fire effects on culturally significant resources and the consequences of fire suppression on terrestrial and riparian habitats. The mechanisms of how fire suppression impacts tribes, resources and tribal land uses are presented. Recommendations are presented for additional research to improve collaboration with tribes, tribal organizations and communities based on contemporary tribal values and priorities for fuels and fire management. Close

• 213. [Article] The slow emergence of the "new father" : understanding fathers' perceptions of messages about fatherhood

  The concept of the "new father" has been discussed in the literature and popular media for over 25 years. Yet current studies regarding father involvement continue to show that fathers do not contribute ...

  Citation × Citation Citation Abstract Copy Title: The slow emergence of the "new father" : understanding fathers' perceptions of messages about fatherhood Author: Day, Jack K. The concept of the "new father" has been discussed in the literature and popular media for over 25 years. Yet current studies regarding father involvement continue to show that fathers do not contribute equally to childcare and domestic labor, even among parents in dual-income families. Furthermore, as roles within families become less differentiated by gender, fathers' roles remain ambiguous. This study investigates fathers' perceptions of social expectations related to fatherhood, and how expectations inform their roles and identities as fathers. This study uses qualitative data to address three central research questions: (a) Where do men receive messages about expectations of them as fathers? (b) What specific messages do fathers receive? (c) Which messages are most meaningful to fathers? Focus groups were conducted with middle-class fathers (n = 17) in dual-income families from a small college community in the northwestern United States. The findings suggest that messages about fatherhood conveyed through television programs are not meaningful to fathers, even though television often reflects cultural norms and social changes in family life. Many fathers in the study also do not identify with many fathers within their own community. Instead, they largely define their roles based on negotiations with their wives, and they emphasize their desire to participate equally in caring for their children. They also turn to fathers in their most inner circles as important anchors for setting their own expectations and judging their own performance as fathers. Yet fathers suggest that other fathers in their community do not display the same level of commitment to fathering as themselves, and they identify persistent low social expectations for fathers as a culprit in men's failure to fully participate in family life. The problem of low expectations is also connected to what fathers see as a larger problem: one in which there are no larger social expectations or scripts to clarify what it is that men should be doing as fathers besides being much more than providers. This study illustrates the importance of understanding how men construct their identities and make meaning of their roles in relation to other fathers, especially those within their communities, a topic that has received little attention in the literature. It also raises questions about the "new father," a concept that is no longer new but for which progress has clearly been slow. The study offers future directions for research on fatherhood, emphasizing the importance of explaining why fathers' involvement, especially in dual-income families, continues to be unequal relative to mothers. Future research also must account for how a variety of reference groups either support fathers in being more involved or, in contrast, simply perpetuate low-expectations for fathers. Title: The slow emergence of the "new father" : understanding fathers' perceptions of messages about fatherhood Author: Day, Jack K. The concept of the "new father" has been discussed in the literature and popular media for over 25 years. Yet current studies regarding father involvement continue to show that fathers do not contribute equally to childcare and domestic labor, even among parents in dual-income families. Furthermore, as roles within families become less differentiated by gender, fathers' roles remain ambiguous. This study investigates fathers' perceptions of social expectations related to fatherhood, and how expectations inform their roles and identities as fathers. This study uses qualitative data to address three central research questions: (a) Where do men receive messages about expectations of them as fathers? (b) What specific messages do fathers receive? (c) Which messages are most meaningful to fathers? Focus groups were conducted with middle-class fathers (n = 17) in dual-income families from a small college community in the northwestern United States. The findings suggest that messages about fatherhood conveyed through television programs are not meaningful to fathers, even though television often reflects cultural norms and social changes in family life. Many fathers in the study also do not identify with many fathers within their own community. Instead, they largely define their roles based on negotiations with their wives, and they emphasize their desire to participate equally in caring for their children. They also turn to fathers in their most inner circles as important anchors for setting their own expectations and judging their own performance as fathers. Yet fathers suggest that other fathers in their community do not display the same level of commitment to fathering as themselves, and they identify persistent low social expectations for fathers as a culprit in men's failure to fully participate in family life. The problem of low expectations is also connected to what fathers see as a larger problem: one in which there are no larger social expectations or scripts to clarify what it is that men should be doing as fathers besides being much more than providers. This study illustrates the importance of understanding how men construct their identities and make meaning of their roles in relation to other fathers, especially those within their communities, a topic that has received little attention in the literature. It also raises questions about the "new father," a concept that is no longer new but for which progress has clearly been slow. The study offers future directions for research on fatherhood, emphasizing the importance of explaining why fathers' involvement, especially in dual-income families, continues to be unequal relative to mothers. Future research also must account for how a variety of reference groups either support fathers in being more involved or, in contrast, simply perpetuate low-expectations for fathers. Close

• 214. [Article] Detailed Morphology and Structure of an Active Submarine Arc Caldera: Brothers Volcano, Kermadec Arc

  This is a scanned version of a published article. The original can be found at: http://econgeol.geoscienceworld.org/. To the best of our knowledge, one or more authors of this paper were federal employees ...

  Citation × Citation Citation Abstract Copy Title: Detailed Morphology and Structure of an Active Submarine Arc Caldera: Brothers Volcano, Kermadec Arc Author: Tontini, F. Caratobi, Davy, B., Merle, S. G., de Ronde, C. E. J., Embley, R. W. This is a scanned version of a published article. The original can be found at: http://econgeol.geoscienceworld.org/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. Title: Detailed Morphology and Structure of an Active Submarine Arc Caldera: Brothers Volcano, Kermadec Arc Author: Tontini, F. Caratobi, Davy, B., Merle, S. G., de Ronde, C. E. J., Embley, R. W. This is a scanned version of a published article. The original can be found at: http://econgeol.geoscienceworld.org/. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. Close

• 215. [Article] Sociability, constraints, network involvement, and the self-esteem of older women

  The major purpose of this exploratory study was to develop an explanatory model of self-esteem and to interpret the model using the Social Exchange framework. To this end, a main effects and an interaction ...

  Citation × Citation Citation Abstract Copy Title: Sociability, constraints, network involvement, and the self-esteem of older women Author: Ames, Sheila A. (Sheila Ann) The major purpose of this exploratory study was to develop an explanatory model of self-esteem and to interpret the model using the Social Exchange framework. To this end, a main effects and an interaction model emerged which offer promise toward understanding the components of self-esteem. This study examined 325 individual variables which served validity and/or descriptive purposes or joined together to form the main variables under investigation. The study extensively interviewed 70 unmarried, white older women who lived alone in age-peer homogeneous residences within the same Northwestern community. Stepwise regression analysis explained 65 percent of the variance in the self-esteem of these older women. In descending order of explained variance, the main effects model revealed that those respondents who felt of little worth -- ... Less often strove to express themselves in meaningful projects ... Were more reluctant to mobilize needed social support in times of undue stress ... Were more intensely involved in family activities, especially advice, than with friends ... Expressed less over-all satisfaction with their network activities, and ... Felt more depressed than those who reported higher self-esteem. The interaction model further disclosed that"when being without a meaningful project" joined with either "family advice" or "reluctance to seek needed help", either combination more negatively correlated with self-esteem than did each variable separately. Three variables, financial adequacy, physical health capacity, and sociability, positively correlated with self-esteem as hypothesized but did not enter the final models. Apparently, the lack of variability of financial adequacy and physical health capacity and the close association between being without a project and sociability prevented these three variables from entering the final equations. However, the respondents' degree of sociability was instrumental in interpreting the results. Specifically, those respondents endowed with a more gregarious nature evidenced higher financial adequacy, greater physical health capacity, more satisfying network activities, and felt less depressed than did the more reserved isolates. Even when constrained by financial, physical health, or relationship losses, the constrained gregarious still maintained higher self-esteem than did the unconstrained isolates. Finally, by being more self-initiating than the isolates, the gregarious respondents sustained their self-esteem by expressing themselves in meaningful projects and by being willing to seek others out for help when their own efforts were insufficient. By more readily substituting feasible opportunities for those they could no longer pursue successfully, the gregarious, more than the isolates, appeared better able to transcend their losses. The isolates, on the other hand, lacked sufficient access to these resources to mobilize the corrective processes that might have enabled them to cope more effectively, and through the process, maintain a positive self-esteem. The study discussed possible implications of this research for influencing the self-esteem of older women and suggested potential directions for future research which might more fully develop the model and expand its application. Title: Sociability, constraints, network involvement, and the self-esteem of older women Author: Ames, Sheila A. (Sheila Ann) The major purpose of this exploratory study was to develop an explanatory model of self-esteem and to interpret the model using the Social Exchange framework. To this end, a main effects and an interaction model emerged which offer promise toward understanding the components of self-esteem. This study examined 325 individual variables which served validity and/or descriptive purposes or joined together to form the main variables under investigation. The study extensively interviewed 70 unmarried, white older women who lived alone in age-peer homogeneous residences within the same Northwestern community. Stepwise regression analysis explained 65 percent of the variance in the self-esteem of these older women. In descending order of explained variance, the main effects model revealed that those respondents who felt of little worth -- ... Less often strove to express themselves in meaningful projects ... Were more reluctant to mobilize needed social support in times of undue stress ... Were more intensely involved in family activities, especially advice, than with friends ... Expressed less over-all satisfaction with their network activities, and ... Felt more depressed than those who reported higher self-esteem. The interaction model further disclosed that"when being without a meaningful project" joined with either "family advice" or "reluctance to seek needed help", either combination more negatively correlated with self-esteem than did each variable separately. Three variables, financial adequacy, physical health capacity, and sociability, positively correlated with self-esteem as hypothesized but did not enter the final models. Apparently, the lack of variability of financial adequacy and physical health capacity and the close association between being without a project and sociability prevented these three variables from entering the final equations. However, the respondents' degree of sociability was instrumental in interpreting the results. Specifically, those respondents endowed with a more gregarious nature evidenced higher financial adequacy, greater physical health capacity, more satisfying network activities, and felt less depressed than did the more reserved isolates. Even when constrained by financial, physical health, or relationship losses, the constrained gregarious still maintained higher self-esteem than did the unconstrained isolates. Finally, by being more self-initiating than the isolates, the gregarious respondents sustained their self-esteem by expressing themselves in meaningful projects and by being willing to seek others out for help when their own efforts were insufficient. By more readily substituting feasible opportunities for those they could no longer pursue successfully, the gregarious, more than the isolates, appeared better able to transcend their losses. The isolates, on the other hand, lacked sufficient access to these resources to mobilize the corrective processes that might have enabled them to cope more effectively, and through the process, maintain a positive self-esteem. The study discussed possible implications of this research for influencing the self-esteem of older women and suggested potential directions for future research which might more fully develop the model and expand its application. Close

• 216. [Article] Silicon biogeochemistry in the open-ocean surface waters : insights from the Sargasso Sea and equatorial Pacific

  Diatoms are a ubiquitous group of plankton responsible for 20-40% of oceanic primary production, and a higher fraction of organic matter export to the ocean interior. Diatoms actively transport dissolved ...

  Citation × Citation Citation Abstract Copy Title: Silicon biogeochemistry in the open-ocean surface waters : insights from the Sargasso Sea and equatorial Pacific Author: Krause, Jeffrey W. Diatoms are a ubiquitous group of plankton responsible for 20-40% of oceanic primary production, and a higher fraction of organic matter export to the ocean interior. Diatoms actively transport dissolved inorganic silicon into their cells, and through the process of silicification (i.e. biogenic silica production) they build tough and intricate shells, known as frustules. With a global distribution and the ability to persist in high numerical abundances, diatoms dominate the biological cycling of Si in the oceans. The biogeochemical cycling of Si has been well studied in the coastal ocean, specifically in upwelling regions where diatoms are generally the dominant phytoplankton group. However, much less is known about the role diatoms play in the open ocean; which comprises the vast majority of the oceanic surface area. Outside of the Southern Ocean, only 11 studies (prior to 2003) directly examined surface-water Si biogeochemistry in the open ocean. Current knowledge about Si biogeochemistry in the open ocean suffers from what can only be described as gross under-sampling. This dissertation reports on the surface-water Si biogeochemistry in two open-ocean regions: the northwestern Sargasso Sea and the eastern equatorial Pacific. The three research chapters are linked by the examination of spatial or temporal variability in surface-water Si biogeochemistry. Chapters 2 and 4 examine scales of temporal variability in Si biogeochemistry in the Sargasso Sea. The results demonstrate that biogenic silica concentrations, and presumably Si biogeochemical processes, vary on daily, seasonal, multi-year (e.g. ~3-4 years), and decadal time scales. In Chapter 3 data were gathered over a ~2.6x106 km2 area (i.e. larger than the Bering Sea) in the equatorial Pacific. Within that area biogenic silica production showed little spatial or temporal variability. Additionally, the estimated contribution to new production (productivity supporting the export of organic matter to the ocean interior) by diatoms in this region was 4-10 times higher than the diatom contribution to total autotrophic biomass. Title: Silicon biogeochemistry in the open-ocean surface waters : insights from the Sargasso Sea and equatorial Pacific Author: Krause, Jeffrey W. Diatoms are a ubiquitous group of plankton responsible for 20-40% of oceanic primary production, and a higher fraction of organic matter export to the ocean interior. Diatoms actively transport dissolved inorganic silicon into their cells, and through the process of silicification (i.e. biogenic silica production) they build tough and intricate shells, known as frustules. With a global distribution and the ability to persist in high numerical abundances, diatoms dominate the biological cycling of Si in the oceans. The biogeochemical cycling of Si has been well studied in the coastal ocean, specifically in upwelling regions where diatoms are generally the dominant phytoplankton group. However, much less is known about the role diatoms play in the open ocean; which comprises the vast majority of the oceanic surface area. Outside of the Southern Ocean, only 11 studies (prior to 2003) directly examined surface-water Si biogeochemistry in the open ocean. Current knowledge about Si biogeochemistry in the open ocean suffers from what can only be described as gross under-sampling. This dissertation reports on the surface-water Si biogeochemistry in two open-ocean regions: the northwestern Sargasso Sea and the eastern equatorial Pacific. The three research chapters are linked by the examination of spatial or temporal variability in surface-water Si biogeochemistry. Chapters 2 and 4 examine scales of temporal variability in Si biogeochemistry in the Sargasso Sea. The results demonstrate that biogenic silica concentrations, and presumably Si biogeochemical processes, vary on daily, seasonal, multi-year (e.g. ~3-4 years), and decadal time scales. In Chapter 3 data were gathered over a ~2.6x106 km2 area (i.e. larger than the Bering Sea) in the equatorial Pacific. Within that area biogenic silica production showed little spatial or temporal variability. Additionally, the estimated contribution to new production (productivity supporting the export of organic matter to the ocean interior) by diatoms in this region was 4-10 times higher than the diatom contribution to total autotrophic biomass. Close

• 217. [Article] Factors affecting the Ceratomyxa shasta infectious cycle and transmission between polychaete and salmonid hosts

  Ceratomyxa shasta is a myxozoan parasite that infects salmonid fishes causing the disease ceratomyxosis that is characterized by severe hemorrhage and necrosis of the intestine and death of the fish host. ...

  Citation × Citation Citation Abstract Copy Title: Factors affecting the Ceratomyxa shasta infectious cycle and transmission between polychaete and salmonid hosts Author: Bjork, Sarah J. Ceratomyxa shasta is a myxozoan parasite that infects salmonid fishes causing the disease ceratomyxosis that is characterized by severe hemorrhage and necrosis of the intestine and death of the fish host. Ceratomyxa shasta is endemic to the Pacific Northwestern United States and Canada, where epizootics are reported for both wild and hatchery reared fish. Identification of factors affecting the infectious cycle of C. shasta is complicated by its obligate two host lifecycle. The parasite infects the fish as an actinospore and develops into a myxospore in the fish host. The myxospore infects the freshwater polychaete, Manayunkia speciosa where the actinospore develops. A system for maintaining and infecting M. speciosa in the laboratory was developed and a series of laboratory studies tested the effects of temperature on polychaete survival, actinospore release and longevity. Temperature did not affect polychaete survival, but actinospore release occurred earlier and in greater abundance at the higher temperature, whereas actinospore longevity and temperature had an inverse relationship. A laboratory flow experiment tested the effects of two flow rates on M. speciosa survival, infection prevalence and fish infection. Polychaetes had higher survival at the fast flow with low infection prevalences compared to polychaetes held in the slow flow treatment. Susceptible rainbow trout became infected when exposed to just 1 actinospore per fish. Fatal infections in these fish were documented at 5 actinospores per fish. Infection prevalence and mean day to death increased with increasing actinospore dose. Fish size did not affect the infective dose; however, parasite dilution did have an effect. Actinospores were labeled with a fluorescent stain and C. shasta attachment to the gills was identified. In situ hybridization of histological sections was used to locate the parasite as it migrated from the gill epithelium, to proliferation in the blood vessel, and migration to the intestine. Quantitative PCR was used to quantify the abundance of the parasite in the blood. When the infection of susceptible and Resistant Chinook salmon were compared, there were no differences in actinospore penetration into the gills but resistant Chinook salmon did eliminate parasites in the blood after 2 weeks and isolate parasites in foci of inflammation in the intestine. Resistant Chinook salmon more effectively regulated an immune response to infection, effectively cleared the parasite showed evidence of recovery after infection. The research presented here has been fundamental in performing C. shasta infection studies in the laboratory in the fish and polychaete hosts. It has greatly affected our understanding of host parasite interactions including the infective dose for rainbow trout and the recognition of the gills and blood as early sites of C. shasta infection. It has also revealed differences in fish host response to infection including the characterization of a recovery from C. shasta infection. Title: Factors affecting the Ceratomyxa shasta infectious cycle and transmission between polychaete and salmonid hosts Author: Bjork, Sarah J. Ceratomyxa shasta is a myxozoan parasite that infects salmonid fishes causing the disease ceratomyxosis that is characterized by severe hemorrhage and necrosis of the intestine and death of the fish host. Ceratomyxa shasta is endemic to the Pacific Northwestern United States and Canada, where epizootics are reported for both wild and hatchery reared fish. Identification of factors affecting the infectious cycle of C. shasta is complicated by its obligate two host lifecycle. The parasite infects the fish as an actinospore and develops into a myxospore in the fish host. The myxospore infects the freshwater polychaete, Manayunkia speciosa where the actinospore develops. A system for maintaining and infecting M. speciosa in the laboratory was developed and a series of laboratory studies tested the effects of temperature on polychaete survival, actinospore release and longevity. Temperature did not affect polychaete survival, but actinospore release occurred earlier and in greater abundance at the higher temperature, whereas actinospore longevity and temperature had an inverse relationship. A laboratory flow experiment tested the effects of two flow rates on M. speciosa survival, infection prevalence and fish infection. Polychaetes had higher survival at the fast flow with low infection prevalences compared to polychaetes held in the slow flow treatment. Susceptible rainbow trout became infected when exposed to just 1 actinospore per fish. Fatal infections in these fish were documented at 5 actinospores per fish. Infection prevalence and mean day to death increased with increasing actinospore dose. Fish size did not affect the infective dose; however, parasite dilution did have an effect. Actinospores were labeled with a fluorescent stain and C. shasta attachment to the gills was identified. In situ hybridization of histological sections was used to locate the parasite as it migrated from the gill epithelium, to proliferation in the blood vessel, and migration to the intestine. Quantitative PCR was used to quantify the abundance of the parasite in the blood. When the infection of susceptible and Resistant Chinook salmon were compared, there were no differences in actinospore penetration into the gills but resistant Chinook salmon did eliminate parasites in the blood after 2 weeks and isolate parasites in foci of inflammation in the intestine. Resistant Chinook salmon more effectively regulated an immune response to infection, effectively cleared the parasite showed evidence of recovery after infection. The research presented here has been fundamental in performing C. shasta infection studies in the laboratory in the fish and polychaete hosts. It has greatly affected our understanding of host parasite interactions including the infective dose for rainbow trout and the recognition of the gills and blood as early sites of C. shasta infection. It has also revealed differences in fish host response to infection including the characterization of a recovery from C. shasta infection. Close

• 218. [Article] Community gradients of Arctic macrolichens in relation to succession, grazing and the environment

  The purpose of this dissertation was to define macrolichen community gradients in relation to succession, grazing and the environment. First, species scores indicating when macrolichen species appeared ...

  Citation × Citation Citation Abstract Copy Title: Community gradients of Arctic macrolichens in relation to succession, grazing and the environment Author: Holt, Emily A. The purpose of this dissertation was to define macrolichen community gradients in relation to succession, grazing and the environment. First, species scores indicating when macrolichen species appeared following disturbance were derived from the literature. Weighted averaging of these data with a community matrix created a successional score for each sample unit of interest. These scores are surrogates for community age for subsequent analyses. I then described lichen community structure and its relation to the environment in the Bering Land Bridge National Preserve (BELA) in northwestern Alaska. Two primary gradients in lichen community composition were related to habitat rockiness and a substrate-topographic gradient. Next, I sought impacts of grazing by reindeer and caribou on lichen communities. I found lightly grazed areas had taller lichens, greater total lichen cover and minor but significant changes in community structure than heavily grazed sites. Lichen species richness, however, did not differ by grazing status. To create a generalized recovery model, I used plots in burned areas and found total lichen and bryophyte cover varied with time since fire (range 4-49 yrs since fire), while vascular plant cover showed no trend. I then compared these patterns to BELA, an area of unknown disturbance history. Low lichen cover in BELA may not necessarily reflect disturbance but rather site or climatic differences. Lastly, I found that all 17 GIS variables separated lichen communities to some degree. Separation of lichen communities by variable ranged from strong (Alaska Subsections, soil and surficial geology variables) to weak (Watersheds and Reindeer Ownership). The quality of the underlying relationships, how finely the groups are divided and the average patch size of each variable also contribute to differences in how clearly lichen communities were separated. This work will serve as a baseline for future comparisons to understand implications of climate and land use change on lichen communities. My grazing results may inform managers of the implications of heavy grazing and underscore protection and monitoring of prolific and diverse sites. In addition, this work contributes a new method to age tundra communities and a list of GIS variable successful at separating lichen communities. Title: Community gradients of Arctic macrolichens in relation to succession, grazing and the environment Author: Holt, Emily A. The purpose of this dissertation was to define macrolichen community gradients in relation to succession, grazing and the environment. First, species scores indicating when macrolichen species appeared following disturbance were derived from the literature. Weighted averaging of these data with a community matrix created a successional score for each sample unit of interest. These scores are surrogates for community age for subsequent analyses. I then described lichen community structure and its relation to the environment in the Bering Land Bridge National Preserve (BELA) in northwestern Alaska. Two primary gradients in lichen community composition were related to habitat rockiness and a substrate-topographic gradient. Next, I sought impacts of grazing by reindeer and caribou on lichen communities. I found lightly grazed areas had taller lichens, greater total lichen cover and minor but significant changes in community structure than heavily grazed sites. Lichen species richness, however, did not differ by grazing status. To create a generalized recovery model, I used plots in burned areas and found total lichen and bryophyte cover varied with time since fire (range 4-49 yrs since fire), while vascular plant cover showed no trend. I then compared these patterns to BELA, an area of unknown disturbance history. Low lichen cover in BELA may not necessarily reflect disturbance but rather site or climatic differences. Lastly, I found that all 17 GIS variables separated lichen communities to some degree. Separation of lichen communities by variable ranged from strong (Alaska Subsections, soil and surficial geology variables) to weak (Watersheds and Reindeer Ownership). The quality of the underlying relationships, how finely the groups are divided and the average patch size of each variable also contribute to differences in how clearly lichen communities were separated. This work will serve as a baseline for future comparisons to understand implications of climate and land use change on lichen communities. My grazing results may inform managers of the implications of heavy grazing and underscore protection and monitoring of prolific and diverse sites. In addition, this work contributes a new method to age tundra communities and a list of GIS variable successful at separating lichen communities. Close

• 219. [Article] Small mammal and bird abundance in relation to post-fire habitat succession in mountain big sagebrush (Artemisia tridentata ssp. vaseyana) communities

  Fire is an important disturbance mechanism in big sagebrush (Artemisia tridentata) communities, yet little is known about wildlife population dynamics during post-fire habitat succession. I estimated the ...

  Citation × Citation Citation Abstract Copy Title: Small mammal and bird abundance in relation to post-fire habitat succession in mountain big sagebrush (Artemisia tridentata ssp. vaseyana) communities Author: Holmes, Aaron L. Fire is an important disturbance mechanism in big sagebrush (Artemisia tridentata) communities, yet little is known about wildlife population dynamics during post-fire habitat succession. I estimated the abundance of small mammals and birds in relation to fire history in mountain big sagebrush (A.t. spp. vaseyana) communities on the Sheldon National Wildlife Refuge in the northwestern Great Basin, USA. I employed a chronosequence approach that took advantage of multiple wildfires that had occurred in similar plant communities between 7 to 20 years prior to sampling. Belding’s ground squirrel (Spermophilus beldingii) were approximately 10 times as abundant in burned areas relative to adjacent unburned habitat regardless of the number of years since a burn occurred. Deer mouse (Peromyscus maniculatus) was more abundant on more recently burned sites, but not at sites closer to full vegetation recovery. Great basin pocket mouse (Perognathus parvus), sagebrush vole (Lemmiscus curtatus), and least chipmunk (Tamius minimus) abundance did not vary as a function of fire history, but some variance was explained by habitat features such as rocky areas and the canopy characteristics of sagebrush. Bird diversity was higher in unburned habitats irrespective of the number of years of recovery out to 20 years. Nine of the 12 most widely occurring species of birds in the study have population densities influenced by fire or post-fire habitat succession to at least 13 to 20 years following a burn. Sage Sparrow (Amphispiza belli), Black-throated Sparrow (Amphispiza bilineata), and Spotted Towhee (Pipilo maculatus) occurred at relatively low densities and were nearly restricted to unburned habitats. Green-tailed Towhee (Pipilo Chlorurus), Gray Flycatcher (Empidonax wrightii), American Robin (Turdus migratorius), and Brown-headed Cowbird (Molothus ater) occurred at lower densities in burned areas than adjacent unburned areas although the relationship was not strong for the latter two species. The magnitude of the difference in density between burned and unburned sites within a landscape diminished with the number of years of vegetation recovery for Green-tailed Towhee. Brewer’s Sparrow (Spizella brewerii) occurred at lower densities relative to adjacent habitat in the most recent burn, but occurred at higher densities after 20 years of habitat succession, suggesting a positive response with a multiple decade lag period. Horned Lark (Eremophila alpestris) and Vesper Sparrow (Pooecetes gramineus) respond positively to fire, but densities were similar to unburned areas after 20 years of habitat succession. An ordination analysis captured 86% of the variation in 12 bird species with 3 orthogonal axes. My research demonstrates that strong community structure exists for birds associated with mountain big sagebrush habitats, and that fire influences community structure for multiple decades. Title: Small mammal and bird abundance in relation to post-fire habitat succession in mountain big sagebrush (Artemisia tridentata ssp. vaseyana) communities Author: Holmes, Aaron L. Fire is an important disturbance mechanism in big sagebrush (Artemisia tridentata) communities, yet little is known about wildlife population dynamics during post-fire habitat succession. I estimated the abundance of small mammals and birds in relation to fire history in mountain big sagebrush (A.t. spp. vaseyana) communities on the Sheldon National Wildlife Refuge in the northwestern Great Basin, USA. I employed a chronosequence approach that took advantage of multiple wildfires that had occurred in similar plant communities between 7 to 20 years prior to sampling. Belding’s ground squirrel (Spermophilus beldingii) were approximately 10 times as abundant in burned areas relative to adjacent unburned habitat regardless of the number of years since a burn occurred. Deer mouse (Peromyscus maniculatus) was more abundant on more recently burned sites, but not at sites closer to full vegetation recovery. Great basin pocket mouse (Perognathus parvus), sagebrush vole (Lemmiscus curtatus), and least chipmunk (Tamius minimus) abundance did not vary as a function of fire history, but some variance was explained by habitat features such as rocky areas and the canopy characteristics of sagebrush. Bird diversity was higher in unburned habitats irrespective of the number of years of recovery out to 20 years. Nine of the 12 most widely occurring species of birds in the study have population densities influenced by fire or post-fire habitat succession to at least 13 to 20 years following a burn. Sage Sparrow (Amphispiza belli), Black-throated Sparrow (Amphispiza bilineata), and Spotted Towhee (Pipilo maculatus) occurred at relatively low densities and were nearly restricted to unburned habitats. Green-tailed Towhee (Pipilo Chlorurus), Gray Flycatcher (Empidonax wrightii), American Robin (Turdus migratorius), and Brown-headed Cowbird (Molothus ater) occurred at lower densities in burned areas than adjacent unburned areas although the relationship was not strong for the latter two species. The magnitude of the difference in density between burned and unburned sites within a landscape diminished with the number of years of vegetation recovery for Green-tailed Towhee. Brewer’s Sparrow (Spizella brewerii) occurred at lower densities relative to adjacent habitat in the most recent burn, but occurred at higher densities after 20 years of habitat succession, suggesting a positive response with a multiple decade lag period. Horned Lark (Eremophila alpestris) and Vesper Sparrow (Pooecetes gramineus) respond positively to fire, but densities were similar to unburned areas after 20 years of habitat succession. An ordination analysis captured 86% of the variation in 12 bird species with 3 orthogonal axes. My research demonstrates that strong community structure exists for birds associated with mountain big sagebrush habitats, and that fire influences community structure for multiple decades. Close

• 220. [Article] Plate boundary deformation of the Pacific plate : two case studies

  Two examples of Pacific rim plate boundary deformation are presented. In the first part of the thesis crustal models are derived for the northwestern part of the Vizcaino block in California using marine ...

  Citation × Citation Citation Abstract Copy Title: Plate boundary deformation of the Pacific plate : two case studies Author: Leitner, Beate Two examples of Pacific rim plate boundary deformation are presented. In the first part of the thesis crustal models are derived for the northwestern part of the Vizcaino block in California using marine seismic and gravity data collected by the Mendocino Triple Junction Seismic Experiment. A northwest-southeast trending kink in the Moho is imaged and interpreted to have formed under compression by reactivation of preexisting thrust faults in the paleoaccretionary prism at the seaward margin of the Vizcaino block. The study suggests that the deformation resulted from mainly north-south compression between the Pacific-Juan de Fuca plates across the Mendocino transform fault and predates late Pliocene Pacific-North America plate convergence. In the second part, 195 earthquakes recorded during the duration of the Southern Alps Passive Seismic Experiment (SAPSE) are analysed. Precise earthquake locations and focal mechanisms provide unprecedented detail of the seismotectonics in the central South Island. The short term (6 month) SAPSE seismicity is compared with long term (8 years) seismicity recorded by the New Zealand National Seismic network and the Lake Pukaki network. The seismicity rate of the Alpine fault is low, but comparable to locked sections of the San Andreas fault, with large earthquakes expected. Changes of the depth of the seismogenic zone, generally uniform at about 10-12 km, occur only localised over distances smaller than 30 km, suggesting that thermal perturbations must be of similar scale. This implies that the thermal effects of the uplift of the Southern Alps do not change the seismogenic depth significantly and are not in accordance with most of the present thermal models. Both the Hope and Porters Pass fault zones are seismically active and deformation is accommodated near the fault zones and in the adjacent crust. North of Mt Cook, a triangular shaped region along the Alpine fault is characterised by absence of earthquakes. We interpret this as the result of the plate boundary shift from the Alpine fault to the Hope and Porters Pass fault zones. The study region shows distributed deformation in a 60-100 km wide zone on NNE-SSW trending thrust faults and strike-slip mechanisms on transfer faults. Title: Plate boundary deformation of the Pacific plate : two case studies Author: Leitner, Beate Two examples of Pacific rim plate boundary deformation are presented. In the first part of the thesis crustal models are derived for the northwestern part of the Vizcaino block in California using marine seismic and gravity data collected by the Mendocino Triple Junction Seismic Experiment. A northwest-southeast trending kink in the Moho is imaged and interpreted to have formed under compression by reactivation of preexisting thrust faults in the paleoaccretionary prism at the seaward margin of the Vizcaino block. The study suggests that the deformation resulted from mainly north-south compression between the Pacific-Juan de Fuca plates across the Mendocino transform fault and predates late Pliocene Pacific-North America plate convergence. In the second part, 195 earthquakes recorded during the duration of the Southern Alps Passive Seismic Experiment (SAPSE) are analysed. Precise earthquake locations and focal mechanisms provide unprecedented detail of the seismotectonics in the central South Island. The short term (6 month) SAPSE seismicity is compared with long term (8 years) seismicity recorded by the New Zealand National Seismic network and the Lake Pukaki network. The seismicity rate of the Alpine fault is low, but comparable to locked sections of the San Andreas fault, with large earthquakes expected. Changes of the depth of the seismogenic zone, generally uniform at about 10-12 km, occur only localised over distances smaller than 30 km, suggesting that thermal perturbations must be of similar scale. This implies that the thermal effects of the uplift of the Southern Alps do not change the seismogenic depth significantly and are not in accordance with most of the present thermal models. Both the Hope and Porters Pass fault zones are seismically active and deformation is accommodated near the fault zones and in the adjacent crust. North of Mt Cook, a triangular shaped region along the Alpine fault is characterised by absence of earthquakes. We interpret this as the result of the plate boundary shift from the Alpine fault to the Hope and Porters Pass fault zones. The study region shows distributed deformation in a 60-100 km wide zone on NNE-SSW trending thrust faults and strike-slip mechanisms on transfer faults. Close