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• 2741. [Article] Developmental toxicity of polycyclic aromatic hydrocarbons : defining mechanisms with systems-based transcriptional profiling

  Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components of fossil fuels and by-products of combustion. Defining toxicity mechanisms for this large family of multi-ring structures ...

  Citation × Citation Citation Abstract Copy Title: Developmental toxicity of polycyclic aromatic hydrocarbons : defining mechanisms with systems-based transcriptional profiling Author: Goodale, Britton C. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components of fossil fuels and by-products of combustion. Defining toxicity mechanisms for this large family of multi-ring structures and substituted derivatives is a substantial challenge. Several PAHs, such as benzo(a)pyrene (BaP), are mutagenic, toxic to wildlife, and classified as probable carcinogens to humans. PAHs are present in the environment both in the gaseous phase as well as associated with particulates, and exposures occur via complex mixtures; combustion emissions contain PAHs along with many other contaminants. Cardiac dysfunction and adverse birth outcomes associated with exposure to airborne PAHs suggest that this family of compounds may have non-mutagenic biological activities that affect human health. Some PAHs exert toxic effects via binding the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor that mediates transcription of many downstream target genes, including cytochrome P450 metabolizing enzymes. Unlike planar halogenated hydrocarbons, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), PAHs are readily metabolized by CYP1A, CYP1B1 and other enzymes, which create reactive intermediates and/or facilitate excretion. Mechanisms of PAH toxicity therefore include canonical AHR signaling, induction of oxidative stress, and other lesser-understood activities that do not require the AHR. We employed zebrafish as a model to rapidly assess developmental toxicity, global transcriptional responses and AHR activation in embryos exposed to parent and oxygenated PAHs (OPAHs). Using comparative analysis of mRNA expression profiles from microarrays with embryos exposed to benz(a)anthracene (BAA), dibenzothiophene (DBT) and pyrene (PYR), we identified expression biomarkers and disrupted biological processes that precede developmental abnormalities. These transcriptional responses were associated with PAH body burdens in the embryos detected by GC-MS. We found that uptake data were essential for discerning molecular pathways from dose-related differences, and identified two primary toxicity profiles. While BAA disrupted transcripts involved in vasculogenesis, DBT and PYR misregulated ion homeostasis and muscle-related genes. NfKB signaling was predicted to be involved in both responses, but canonical AHR signaling was only activated by BAA. In order to study the role of the AHR in mediating toxicity of PAHs, we developed an AHR2 mutant zebrafish line, which has a mutation in the transactivation domain of AHR2. We used AHR agonists TCDD and leflunomide as toxicological probes to characterize AHR activity in the mutant line, and determined that the mutants were functionally null. Finally, we used AHR2 deficient zebrafish embryos to investigate mechanisms by which two four-ring OPAHs induced developmental effects. 1,9 benz-10-anthrone (BEZO) and benz(a)anthracene-7,12-dione (7,12-B[a]AQ) both caused malformations in developing embryos, but they differentially induced CYP1A expression. Despite this difference, the toxicity produced from both compounds was AHR2-dependent. We used mRNA-seq to compare the transcriptional profiles of BEZO and 7,12-B[a]AQ, and identified transcriptional networks that will be investigated further to determine how ligands differentially modulate AHR activity. We also discovered novel transcripts that are potentially important mediators of AHR toxic effects. Comparison across all five parent and OPAHs highlighted clusters of genes that, surprisingly, were similarly expressed in response to the OPAHs, DBT and PYR. These commonly-regulated transcripts may be important to consider when investigating toxicity of PAH mixtures. Together, these studies show that PAHs act via different transcriptional mechanisms, but can be categorized based on transcriptional profiles and differential AHR activation. The clusters of transcripts identified may be involved in common pathways; further investigation of transcription factors and coactivators that interact with mixexpressed genes is a promising area of research for elucidating diverse functions of the AHR. Title: Developmental toxicity of polycyclic aromatic hydrocarbons : defining mechanisms with systems-based transcriptional profiling Author: Goodale, Britton C. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment as components of fossil fuels and by-products of combustion. Defining toxicity mechanisms for this large family of multi-ring structures and substituted derivatives is a substantial challenge. Several PAHs, such as benzo(a)pyrene (BaP), are mutagenic, toxic to wildlife, and classified as probable carcinogens to humans. PAHs are present in the environment both in the gaseous phase as well as associated with particulates, and exposures occur via complex mixtures; combustion emissions contain PAHs along with many other contaminants. Cardiac dysfunction and adverse birth outcomes associated with exposure to airborne PAHs suggest that this family of compounds may have non-mutagenic biological activities that affect human health. Some PAHs exert toxic effects via binding the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor that mediates transcription of many downstream target genes, including cytochrome P450 metabolizing enzymes. Unlike planar halogenated hydrocarbons, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), PAHs are readily metabolized by CYP1A, CYP1B1 and other enzymes, which create reactive intermediates and/or facilitate excretion. Mechanisms of PAH toxicity therefore include canonical AHR signaling, induction of oxidative stress, and other lesser-understood activities that do not require the AHR. We employed zebrafish as a model to rapidly assess developmental toxicity, global transcriptional responses and AHR activation in embryos exposed to parent and oxygenated PAHs (OPAHs). Using comparative analysis of mRNA expression profiles from microarrays with embryos exposed to benz(a)anthracene (BAA), dibenzothiophene (DBT) and pyrene (PYR), we identified expression biomarkers and disrupted biological processes that precede developmental abnormalities. These transcriptional responses were associated with PAH body burdens in the embryos detected by GC-MS. We found that uptake data were essential for discerning molecular pathways from dose-related differences, and identified two primary toxicity profiles. While BAA disrupted transcripts involved in vasculogenesis, DBT and PYR misregulated ion homeostasis and muscle-related genes. NfKB signaling was predicted to be involved in both responses, but canonical AHR signaling was only activated by BAA. In order to study the role of the AHR in mediating toxicity of PAHs, we developed an AHR2 mutant zebrafish line, which has a mutation in the transactivation domain of AHR2. We used AHR agonists TCDD and leflunomide as toxicological probes to characterize AHR activity in the mutant line, and determined that the mutants were functionally null. Finally, we used AHR2 deficient zebrafish embryos to investigate mechanisms by which two four-ring OPAHs induced developmental effects. 1,9 benz-10-anthrone (BEZO) and benz(a)anthracene-7,12-dione (7,12-B[a]AQ) both caused malformations in developing embryos, but they differentially induced CYP1A expression. Despite this difference, the toxicity produced from both compounds was AHR2-dependent. We used mRNA-seq to compare the transcriptional profiles of BEZO and 7,12-B[a]AQ, and identified transcriptional networks that will be investigated further to determine how ligands differentially modulate AHR activity. We also discovered novel transcripts that are potentially important mediators of AHR toxic effects. Comparison across all five parent and OPAHs highlighted clusters of genes that, surprisingly, were similarly expressed in response to the OPAHs, DBT and PYR. These commonly-regulated transcripts may be important to consider when investigating toxicity of PAH mixtures. Together, these studies show that PAHs act via different transcriptional mechanisms, but can be categorized based on transcriptional profiles and differential AHR activation. The clusters of transcripts identified may be involved in common pathways; further investigation of transcription factors and coactivators that interact with mixexpressed genes is a promising area of research for elucidating diverse functions of the AHR. Close

• 2742. [Article] California condors in the Pacific Northwest : integrating history, molecular ecology, and spatial modeling for reintroduction planning

  Reintroduction programs are increasingly being used to save animals from extinction and aid in their recovery. The California Condor (Gymnogyps californianus), one of the most endangered birds in the ...

  Citation × Citation Citation Abstract Copy Title: California condors in the Pacific Northwest : integrating history, molecular ecology, and spatial modeling for reintroduction planning Author: D'Elia, Jesse Reintroduction programs are increasingly being used to save animals from extinction and aid in their recovery. The California Condor (Gymnogyps californianus), one of the most endangered birds in the world, is a remarkable example of how reintroduction programs can help rapidly increase a species' population numbers and range following a population bottleneck. Despite these gains, condors remain a critically endangered species and are absent from the northern half of their historical range. Here I evaluated questions concerning the biological feasibility of reintroducing California Condors to their former range in the Pacific Northwest using a multidisciplinary approach, employing the fields of history, molecular ecology, and spatial modeling. A review of the historical evidence, including the archeological and paleontological record, use of condors in Native American culture, and early historical accounts of explorers and naturalists, suggest that condors were once widely distributed and likely abundant in the Pacific Northwest. It is also likely that they were breeding birds in the region, rather than seasonal migrants. Examination of 526 base pairs from the control region of mitochondrial DNA (mtDNA) harvested from California Condor museum samples (n = 67) and genetic founders of the captive population (n =14) revealed 18 haplotypes in the historical population, 14 of which have not been reported previously. Only three of these haplotypes survived the genetic bottleneck, indicating > 80% reduction in haplotype richness. This substantial loss of genetic diversity is consistent with the hypothesis that condor populations were relatively abundant at the time of Euro-American contact, but declined rapidly as a result of human causes. I found no spatial sorting of haplotypes in the historical population, which suggests historical gene flow between the Pacific Northwest and southern and central California. Therefore, conservation strategies should consider restoring rangewide metapopulation connectivity when planning future reintroductions. Finally, I developed and tested activity-specific ecological niche models (nesting, roosting, and feeding) to identify areas in the Pacific Northwest that have retained ecological characteristics similar to those where condors have been observed in the last several decades. These models were integrated with information on condor movement ecology and biology to produce predictive maps of reintroduction site suitability across California, Oregon, and Washington. Ecological niche models were consistent with published knowledge of California Condor ecology, had good predictive performance when tested with data withheld from model development, and identified several candidate reintroduction areas. Results suggest that > 70% of the modeled nesting habitat and > 60% of the modeled roosting and foraging habitat in Washington, Oregon, and California is currently unoccupied. Thus, there are large unoccupied regions of the California Condor’s historical range in the Pacific Northwest that still possess relevant ecological features similar to currently occupied habitats, and therefore warrant consideration for future reintroduction efforts. In summary, this study provides foundational information to inform condor reintroductions to the Pacific Northwest. Key findings include: (1) extensive evidence that condors previously occupied the Pacific Northwest, likely in large numbers, prior to Euro-American expansion; (2) the lack of historical population structure, suggestive of historical gene flow between condor populations in the Pacific Northwest and elsewhere in the range; and, (3) identification of several candidate reintroduction areas in the Pacific Northwest that have retained environmental conditions that appear suitable for condor recovery. Title: California condors in the Pacific Northwest : integrating history, molecular ecology, and spatial modeling for reintroduction planning Author: D'Elia, Jesse Reintroduction programs are increasingly being used to save animals from extinction and aid in their recovery. The California Condor (Gymnogyps californianus), one of the most endangered birds in the world, is a remarkable example of how reintroduction programs can help rapidly increase a species' population numbers and range following a population bottleneck. Despite these gains, condors remain a critically endangered species and are absent from the northern half of their historical range. Here I evaluated questions concerning the biological feasibility of reintroducing California Condors to their former range in the Pacific Northwest using a multidisciplinary approach, employing the fields of history, molecular ecology, and spatial modeling. A review of the historical evidence, including the archeological and paleontological record, use of condors in Native American culture, and early historical accounts of explorers and naturalists, suggest that condors were once widely distributed and likely abundant in the Pacific Northwest. It is also likely that they were breeding birds in the region, rather than seasonal migrants. Examination of 526 base pairs from the control region of mitochondrial DNA (mtDNA) harvested from California Condor museum samples (n = 67) and genetic founders of the captive population (n =14) revealed 18 haplotypes in the historical population, 14 of which have not been reported previously. Only three of these haplotypes survived the genetic bottleneck, indicating > 80% reduction in haplotype richness. This substantial loss of genetic diversity is consistent with the hypothesis that condor populations were relatively abundant at the time of Euro-American contact, but declined rapidly as a result of human causes. I found no spatial sorting of haplotypes in the historical population, which suggests historical gene flow between the Pacific Northwest and southern and central California. Therefore, conservation strategies should consider restoring rangewide metapopulation connectivity when planning future reintroductions. Finally, I developed and tested activity-specific ecological niche models (nesting, roosting, and feeding) to identify areas in the Pacific Northwest that have retained ecological characteristics similar to those where condors have been observed in the last several decades. These models were integrated with information on condor movement ecology and biology to produce predictive maps of reintroduction site suitability across California, Oregon, and Washington. Ecological niche models were consistent with published knowledge of California Condor ecology, had good predictive performance when tested with data withheld from model development, and identified several candidate reintroduction areas. Results suggest that > 70% of the modeled nesting habitat and > 60% of the modeled roosting and foraging habitat in Washington, Oregon, and California is currently unoccupied. Thus, there are large unoccupied regions of the California Condor’s historical range in the Pacific Northwest that still possess relevant ecological features similar to currently occupied habitats, and therefore warrant consideration for future reintroduction efforts. In summary, this study provides foundational information to inform condor reintroductions to the Pacific Northwest. Key findings include: (1) extensive evidence that condors previously occupied the Pacific Northwest, likely in large numbers, prior to Euro-American expansion; (2) the lack of historical population structure, suggestive of historical gene flow between condor populations in the Pacific Northwest and elsewhere in the range; and, (3) identification of several candidate reintroduction areas in the Pacific Northwest that have retained environmental conditions that appear suitable for condor recovery. Close

• 2743. [Article] Worldwide phylogeography and local population structure of the rough-toothed dolphin (Steno bredanensis)

  Several dolphin species have global distributions. The extent of their radiation and limits to gene flow are presumably a product of oceanographic features both recent and historical, behavioral specializations ...

  Citation × Citation Citation Abstract Copy Title: Worldwide phylogeography and local population structure of the rough-toothed dolphin (Steno bredanensis) Author: Albertson, G. Renee Several dolphin species have global distributions. The extent of their radiation and limits to gene flow are presumably a product of oceanographic features both recent and historical, behavioral specializations and social organization. Rough-toothed dolphins (Steno bredanensis) are globally distributed in tropical and subtropical waters and are generally found in depths greater than 1,500 meters making them challenging to comprehensively sample. Although it has been assumed that pelagic dolphins range widely due to the lack of apparent barriers and unpredictable prey distribution, recent evidence suggests rough-toothed dolphins exhibit fidelity to some oceanic islands. A small number of photo-identification and genetic studies conducted to date on rough-toothed dolphins show regional population structure and stable associations in groups, with some individuals observed repeatedly in the same groups over several years. The aim of this dissertation is to describe patterns of phylogeography over evolutionary time on a global scale and expand studies of population and social structure on a regional level. The dataset contains 351 rough-toothed dolphin biopsies, tissue and teeth samples collected from the Pacific and Atlantic Oceans and limited samples from the Indian Ocean. To evaluate the phylogeography and test for possible species or subspecies level delineation between oceans, I used mitochondrial DNA sequences from the control region (350 bp) and 12 concatenated protein-coding genes from the whole mitogenome, as well as six nuclear introns. Although I found support for two Pacific clades and a private North Atlantic clade in the whole mitogenome, there were no genealogical patterns consistent across multiple loci, allowing me to reject species level delineation. To further evaluate the amount of gene flow and test for divisions below the species level, I used population level indices and found significant genetic differentiation for rough-toothed dolphins between the Atlantic Ocean with both the Indian/Western Pacific and Central/Eastern Pacific for both the mitochondrial datasets and the intron dataset. Significant differentiation between the Indian/Western Pacific Ocean and Eastern Pacific Ocean was found for the mitochondrial but not nuclear datasets. From these results I recommended the Atlantic Ocean basin be considered a separate evolutionary significant unit. This reflects that these populations are on independent evolutionary trajectories, but are not diagnosable species or subspecies. To further evaluate population structure on a regional scale, I used a subset of these samples from three archipelagos in the Central Pacific Ocean including the Hawaiian Islands, the Society Island of French Polynesia and the Samoan Islands. Using a 450bp portion of the mtDNA control region and 15 microsatellite loci, an overall AMOVA indicated strong genetic differentiation among islands within the main Hawaiian Islands (mtDNA F[subscript ST]=0.165; p<0.001; microsatellite F[subscript ST]=0.043 p<0.001) and the Society Islands of French Polynesia (F[subscript ST]=0.499; p<0.001; microsatellite F[subscript ST]=0.079 p<0.001) as well as among the three archipelagos (mtDNA F[subscript ST]=0.299; p<0.001; microsatellite F[subscript ST]=0.055 p<0.001). My results corroborate the photo-identification and the genetic studies for three archipelagos, confirming population structure on the regional level. Lastly, to test the hypothesis that social structure observed in rough-toothed dolphins is kinship based, as in other delphinid species such as killer whales, I used a subset of the main dataset from groups of living and mass stranded dolphins. I found multiple matrilines in more than half the groups, allowing me to reject a strictly matrilineal group structure, such as that observed in some killer whales. Instead I found rough-toothed dolphin groups showed weak matrilineality, where some groups are more matrilineal than expected by chance. Although group structure is stable, is not determined primarily by kin-based relationships. These analyses provide new insights into a little studied species. The use of worldwide datasets allowed me to evaluate population structure on different temporal, spatial and regional scales and delineate populations for future conservation and management. Title: Worldwide phylogeography and local population structure of the rough-toothed dolphin (Steno bredanensis) Author: Albertson, G. Renee Several dolphin species have global distributions. The extent of their radiation and limits to gene flow are presumably a product of oceanographic features both recent and historical, behavioral specializations and social organization. Rough-toothed dolphins (Steno bredanensis) are globally distributed in tropical and subtropical waters and are generally found in depths greater than 1,500 meters making them challenging to comprehensively sample. Although it has been assumed that pelagic dolphins range widely due to the lack of apparent barriers and unpredictable prey distribution, recent evidence suggests rough-toothed dolphins exhibit fidelity to some oceanic islands. A small number of photo-identification and genetic studies conducted to date on rough-toothed dolphins show regional population structure and stable associations in groups, with some individuals observed repeatedly in the same groups over several years. The aim of this dissertation is to describe patterns of phylogeography over evolutionary time on a global scale and expand studies of population and social structure on a regional level. The dataset contains 351 rough-toothed dolphin biopsies, tissue and teeth samples collected from the Pacific and Atlantic Oceans and limited samples from the Indian Ocean. To evaluate the phylogeography and test for possible species or subspecies level delineation between oceans, I used mitochondrial DNA sequences from the control region (350 bp) and 12 concatenated protein-coding genes from the whole mitogenome, as well as six nuclear introns. Although I found support for two Pacific clades and a private North Atlantic clade in the whole mitogenome, there were no genealogical patterns consistent across multiple loci, allowing me to reject species level delineation. To further evaluate the amount of gene flow and test for divisions below the species level, I used population level indices and found significant genetic differentiation for rough-toothed dolphins between the Atlantic Ocean with both the Indian/Western Pacific and Central/Eastern Pacific for both the mitochondrial datasets and the intron dataset. Significant differentiation between the Indian/Western Pacific Ocean and Eastern Pacific Ocean was found for the mitochondrial but not nuclear datasets. From these results I recommended the Atlantic Ocean basin be considered a separate evolutionary significant unit. This reflects that these populations are on independent evolutionary trajectories, but are not diagnosable species or subspecies. To further evaluate population structure on a regional scale, I used a subset of these samples from three archipelagos in the Central Pacific Ocean including the Hawaiian Islands, the Society Island of French Polynesia and the Samoan Islands. Using a 450bp portion of the mtDNA control region and 15 microsatellite loci, an overall AMOVA indicated strong genetic differentiation among islands within the main Hawaiian Islands (mtDNA F[subscript ST]=0.165; p<0.001; microsatellite F[subscript ST]=0.043 p<0.001) and the Society Islands of French Polynesia (F[subscript ST]=0.499; p<0.001; microsatellite F[subscript ST]=0.079 p<0.001) as well as among the three archipelagos (mtDNA F[subscript ST]=0.299; p<0.001; microsatellite F[subscript ST]=0.055 p<0.001). My results corroborate the photo-identification and the genetic studies for three archipelagos, confirming population structure on the regional level. Lastly, to test the hypothesis that social structure observed in rough-toothed dolphins is kinship based, as in other delphinid species such as killer whales, I used a subset of the main dataset from groups of living and mass stranded dolphins. I found multiple matrilines in more than half the groups, allowing me to reject a strictly matrilineal group structure, such as that observed in some killer whales. Instead I found rough-toothed dolphin groups showed weak matrilineality, where some groups are more matrilineal than expected by chance. Although group structure is stable, is not determined primarily by kin-based relationships. These analyses provide new insights into a little studied species. The use of worldwide datasets allowed me to evaluate population structure on different temporal, spatial and regional scales and delineate populations for future conservation and management. Close

• 2744. [Article] Dispersal Behavior in African Buffalo (Syncerus caffer) : Tradeoffs Between Nutritional Resources and Disease Exposure

  Dispersal facilitates population health and maintains resilience in species via gene flow. Adult dispersal occurs in some species, is often facultative, and is poorly understood, but has important management ...

  Citation × Citation Citation Abstract Copy Title: Dispersal Behavior in African Buffalo (Syncerus caffer) : Tradeoffs Between Nutritional Resources and Disease Exposure Author: Spaan, Robert Steven Dispersal facilitates population health and maintains resilience in species via gene flow. Adult dispersal occurs in some species, is often facultative, and is poorly understood, but has important management implications, particularly with respect to disease spread. Although the role of adult dispersal in spreading disease has been documented, the potential influence of disease on dispersal has received little attention. African buffalo (Syncerus caffer) are wide ranging and harbor many pathogens that can affect nearby livestock. Dispersal of adult buffalo has been well documented, but ecological and social drivers of buffalo dispersal are poorly understood. At the individual level, animals must balance the potential benefits of dispersal against its costs. Costs may be incurred in the form of risk, such as mortality or potential injury while dispersing, energetic and time costs associated with the energy and time invested in dispersing, and costs associated with lost opportunities, e.g. reduced fecundity due to unfamiliar surroundings and social groups. Disease in particular is another poorly-understood but potentially important factor influencing costs and benefits of dispersal. Dispersal from a crowded habitat may offer an escape from high pathogen and parasite exposure risk, conversely dispersing individuals in this stressful period may have reduced immunity and consequently be more susceptible to infections. In addition, if pathogen exposure profiles differ among social groups, dispersing animals may face new pathogen challenges to which they are immunologically naïve to, when they arrive at a new social group. However, few studies have estimated dispersal costs of large mammals, particularly those with facultative adult dispersal. First, we investigated drivers of adult buffalo dispersal to determine whether likelihood of dispersal for individual female buffalo was influenced by (1) animal traits, including age, condition, and reproductive status (2) herd membership, (3) environmental variables - season and year, (4) gastro-intestinal parasites - strongyles, coccidia and schistosomes and (5) microparasite infections - bovine tuberculosis (Mycobacterium bovis) and brucellosis (Brucella abortus). The likelihood and drivers of buffalo dispersal varied by herd, area and year. In the Lower Sabie herd younger individuals were more likely to disperse, with most dispersal occurring in the early wet season and during an unusually dry year, 2009. In the Crocodile Bridge area buffalo in poor condition were most likely to disperse. Our findings suggest that dispersal of female buffalo is driven by either seasonal (Lower Sabie), or perhaps social (Crocodile Bridge) resource restriction. We found no direct effects of infections on buffalo dispersal, assuaging fears that highly infectious individuals might be more prone to dispersing, which could accelerate the spatial spread of infectious diseases. Second, we investigated: (1) effects of dispersal on fitness, by comparing survival, and fecundity of dispersing and philopatric (control) buffalo, as well as comparing the difference in pre and post dispersal body condition of dispersers with the change of body condition of philopatric control animals for the same period; (2) disease risks associated with dispersal, by determining whether burdens of gastro-intestinal parasites and the incidence of bacterial and viral infections changed during dispersal. No significant difference in mortality risk or fecundity was observed between dispersing and philopatric control animals, nor did change in body condition differ. However, we detected disease consequences of dispersal that varied by location. Dispersers from the resource-limited herd suffered more bovine tuberculosis and brucellosis infections after dispersal, both of which are chronic infections with clear, long term effects on survival and fecundity, when compared to controls from the same location. Dispersers from the less resource-limited herds had increases in schistosome burdens. Schistosomes are parasitic worms with relatively minor health effects; relatively long-lived but not as long as the life of the host (i.e., buffalo can reduce their burdens). Previous work has shown that adult buffalo disperse in response to resource limitation due to seasonal forage shortages or density dependent Title: Dispersal Behavior in African Buffalo (Syncerus caffer) : Tradeoffs Between Nutritional Resources and Disease Exposure Author: Spaan, Robert Steven Dispersal facilitates population health and maintains resilience in species via gene flow. Adult dispersal occurs in some species, is often facultative, and is poorly understood, but has important management implications, particularly with respect to disease spread. Although the role of adult dispersal in spreading disease has been documented, the potential influence of disease on dispersal has received little attention. African buffalo (Syncerus caffer) are wide ranging and harbor many pathogens that can affect nearby livestock. Dispersal of adult buffalo has been well documented, but ecological and social drivers of buffalo dispersal are poorly understood. At the individual level, animals must balance the potential benefits of dispersal against its costs. Costs may be incurred in the form of risk, such as mortality or potential injury while dispersing, energetic and time costs associated with the energy and time invested in dispersing, and costs associated with lost opportunities, e.g. reduced fecundity due to unfamiliar surroundings and social groups. Disease in particular is another poorly-understood but potentially important factor influencing costs and benefits of dispersal. Dispersal from a crowded habitat may offer an escape from high pathogen and parasite exposure risk, conversely dispersing individuals in this stressful period may have reduced immunity and consequently be more susceptible to infections. In addition, if pathogen exposure profiles differ among social groups, dispersing animals may face new pathogen challenges to which they are immunologically naïve to, when they arrive at a new social group. However, few studies have estimated dispersal costs of large mammals, particularly those with facultative adult dispersal. First, we investigated drivers of adult buffalo dispersal to determine whether likelihood of dispersal for individual female buffalo was influenced by (1) animal traits, including age, condition, and reproductive status (2) herd membership, (3) environmental variables - season and year, (4) gastro-intestinal parasites - strongyles, coccidia and schistosomes and (5) microparasite infections - bovine tuberculosis (Mycobacterium bovis) and brucellosis (Brucella abortus). The likelihood and drivers of buffalo dispersal varied by herd, area and year. In the Lower Sabie herd younger individuals were more likely to disperse, with most dispersal occurring in the early wet season and during an unusually dry year, 2009. In the Crocodile Bridge area buffalo in poor condition were most likely to disperse. Our findings suggest that dispersal of female buffalo is driven by either seasonal (Lower Sabie), or perhaps social (Crocodile Bridge) resource restriction. We found no direct effects of infections on buffalo dispersal, assuaging fears that highly infectious individuals might be more prone to dispersing, which could accelerate the spatial spread of infectious diseases. Second, we investigated: (1) effects of dispersal on fitness, by comparing survival, and fecundity of dispersing and philopatric (control) buffalo, as well as comparing the difference in pre and post dispersal body condition of dispersers with the change of body condition of philopatric control animals for the same period; (2) disease risks associated with dispersal, by determining whether burdens of gastro-intestinal parasites and the incidence of bacterial and viral infections changed during dispersal. No significant difference in mortality risk or fecundity was observed between dispersing and philopatric control animals, nor did change in body condition differ. However, we detected disease consequences of dispersal that varied by location. Dispersers from the resource-limited herd suffered more bovine tuberculosis and brucellosis infections after dispersal, both of which are chronic infections with clear, long term effects on survival and fecundity, when compared to controls from the same location. Dispersers from the less resource-limited herds had increases in schistosome burdens. Schistosomes are parasitic worms with relatively minor health effects; relatively long-lived but not as long as the life of the host (i.e., buffalo can reduce their burdens). Previous work has shown that adult buffalo disperse in response to resource limitation due to seasonal forage shortages or density dependent Close

• 2745. [Article] A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Royal Society ...

  Citation × Citation Citation Abstract Copy Title: A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network Author: Torres, Patricia Carignano, Durigan, Mariana, Abramovay, Ricardo, dos Santos, Fabiane Campos, de Melo Ferreira, Amanda Estefania, Aleixo, Alexandre, de Camargo, Plinio Barbosa, Fonseca Oliveira, Victor Hugo, Gardner, Toby A., Zuanon, Jansen, Kaufmann, Phil, Korasaki, Vanesca, Hamada, Neusa, Lopes Almeida, Maria de Fatima, Braga, Rodrigo Fagundes, Solar, Ricardo R. C., Andretti, Christian, Lees, Alexander C., Beldini, Troy, Mario Chaul, Julio Cezar, Parry, Luke, Stulpen Veiga, Ruan Carlo, Lourival, Reinaldo, Moreira, Fatima M. S., Castelani, Sergio Andre, Coudel, Emilie, Barlow, Jos, Juen, Leandro, Viana, Cecilia, Thomson, James R., Gomes, Alessandra dos Santos, Junior, Miercio, Souza Junior, Carlos, de Barros Ferraz, Silvio Frosini, Dalla Mora Esquerdo, Julio Cesar, Batistella, Mateus, de Carvalho, Teotonio Soares, de Oliveira Junior, Jose Max Barbosa, de Avila, Williams Souza, de Blas, Driss Ezzine, Dias-Silva, Karina, Pompeu, Paulo Santos, Flores da Silva, Lenise Vargas, Nessimian, Jorge, Viana Martins da Silva, Regina Celia, Nunes Cordeiro, Amanda Cardoso, da Silva, Rodrigo, Leitao, Rafael, Begotti, Rodrigo Anzolin, Ferreira, Joice, Garrett, Rachel, Marchand, Sebastien, D'Antona, Alvaro, Leal, Cecilia Gontijo, Morsello, Carla, Lima, Natalia, Weinhold, Diana, Schmidt, Fernando Augusto, Hughes, Robert M., Cerri, Carlos Eduardo, Fiorini, Ana Carolina, Berenguer, Erika, de Carvalho, Deborah Reis, Aragao, Luiz E. O. C., Jesus, Ederson da Conceicao, Mac Nally, Ralph, de Oliveira, Vívian Campos, Venturieri, Adriano, Furtado da Costa, Carla Daniele, Holanda Tancredi, Nicola Saverio, Silveira, Juliana, Dezincourt, Joelma, de Oliveira Junior, Raimundo Cosme, Siqueira, Joao Victor, Braga, Danielle de Lima, Cardoso, Thiago Moreira, Zanetti, Ronald, Bardgett, Richard D., Guimaraes Vieira, Ima Celia, Feres, Jose, Rossetti, Felipe, Ribas, Carla Rodrigues, Nunes, Samia, Cunha, Denis, Morello Ramalho da Silva, Thiago Fonseca, de Brito, Janaina Gomes, Pardini, Renata, Coutinho, Alexandre Camargo, Goncalves, Karoline da Silva, Frazao, Fabio Soares, Igliori, Danilo Carmago, Araujo, Ivanei, Maues, Marcia Motta, Louzada, Julio, Vaz-de-Mello, Fernando Zagury, Moura, Nargila, Guerrero, Jose Benito, Costa, Francisco de Assis, Pereira, Heloisa Correia To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Royal Society Publishing and can be found at: http://royalsocietypublishing.org/journals. Title: A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network Author: Torres, Patricia Carignano, Durigan, Mariana, Abramovay, Ricardo, dos Santos, Fabiane Campos, de Melo Ferreira, Amanda Estefania, Aleixo, Alexandre, de Camargo, Plinio Barbosa, Fonseca Oliveira, Victor Hugo, Gardner, Toby A., Zuanon, Jansen, Kaufmann, Phil, Korasaki, Vanesca, Hamada, Neusa, Lopes Almeida, Maria de Fatima, Braga, Rodrigo Fagundes, Solar, Ricardo R. C., Andretti, Christian, Lees, Alexander C., Beldini, Troy, Mario Chaul, Julio Cezar, Parry, Luke, Stulpen Veiga, Ruan Carlo, Lourival, Reinaldo, Moreira, Fatima M. S., Castelani, Sergio Andre, Coudel, Emilie, Barlow, Jos, Juen, Leandro, Viana, Cecilia, Thomson, James R., Gomes, Alessandra dos Santos, Junior, Miercio, Souza Junior, Carlos, de Barros Ferraz, Silvio Frosini, Dalla Mora Esquerdo, Julio Cesar, Batistella, Mateus, de Carvalho, Teotonio Soares, de Oliveira Junior, Jose Max Barbosa, de Avila, Williams Souza, de Blas, Driss Ezzine, Dias-Silva, Karina, Pompeu, Paulo Santos, Flores da Silva, Lenise Vargas, Nessimian, Jorge, Viana Martins da Silva, Regina Celia, Nunes Cordeiro, Amanda Cardoso, da Silva, Rodrigo, Leitao, Rafael, Begotti, Rodrigo Anzolin, Ferreira, Joice, Garrett, Rachel, Marchand, Sebastien, D'Antona, Alvaro, Leal, Cecilia Gontijo, Morsello, Carla, Lima, Natalia, Weinhold, Diana, Schmidt, Fernando Augusto, Hughes, Robert M., Cerri, Carlos Eduardo, Fiorini, Ana Carolina, Berenguer, Erika, de Carvalho, Deborah Reis, Aragao, Luiz E. O. C., Jesus, Ederson da Conceicao, Mac Nally, Ralph, de Oliveira, Vívian Campos, Venturieri, Adriano, Furtado da Costa, Carla Daniele, Holanda Tancredi, Nicola Saverio, Silveira, Juliana, Dezincourt, Joelma, de Oliveira Junior, Raimundo Cosme, Siqueira, Joao Victor, Braga, Danielle de Lima, Cardoso, Thiago Moreira, Zanetti, Ronald, Bardgett, Richard D., Guimaraes Vieira, Ima Celia, Feres, Jose, Rossetti, Felipe, Ribas, Carla Rodrigues, Nunes, Samia, Cunha, Denis, Morello Ramalho da Silva, Thiago Fonseca, de Brito, Janaina Gomes, Pardini, Renata, Coutinho, Alexandre Camargo, Goncalves, Karoline da Silva, Frazao, Fabio Soares, Igliori, Danilo Carmago, Araujo, Ivanei, Maues, Marcia Motta, Louzada, Julio, Vaz-de-Mello, Fernando Zagury, Moura, Nargila, Guerrero, Jose Benito, Costa, Francisco de Assis, Pereira, Heloisa Correia To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Royal Society Publishing and can be found at: http://royalsocietypublishing.org/journals. Close

• 2746. [Article] The ecology of riparian ecosystems of Northeast Oregon : shrub recovery at Meadow Creek and the structure and biomass of headwater Upper Grande Ronde ecosystems

  Riparian ecosystems play numerous and essential roles related to the quality and flow of water, and food/habitat for fish, and varieties of wildlife. Due to lateral and linear linkages throughout the landscape, ...

  Citation × Citation Citation Abstract Copy Title: The ecology of riparian ecosystems of Northeast Oregon : shrub recovery at Meadow Creek and the structure and biomass of headwater Upper Grande Ronde ecosystems Author: Case, Richard L. Riparian ecosystems play numerous and essential roles related to the quality and flow of water, and food/habitat for fish, and varieties of wildlife. Due to lateral and linear linkages throughout the landscape, these zones influence the integrity of the terrestrial as well as the entire aquatic-riverine ecosystem. Since Euro-American settlement in the West, the structure and condition of many riparian ecosystems has been significantly altered. To provide tools and an ecological perspective related to riparian restoration and management, and to document late 20th century headwater riparian structure and biomass in the Upper Grande Ronde Basin, this research project was undertaken. At Meadow Creek, the response of riparian hardwood species to the termination of livestock grazing was quantified. Regression equations were developed to predict shrub biomass. Permanently marked hardwood plants were measured annually to quantify parameters of growth (height, crown area, mainstem diameter, number of stems, biomass). Permanent belt transects on gravel bars were utilized to quantify rates of shrub establishment. Elk/deer-proof exclosures allowed the quantification of the browsing influence of wild ungulates. In 1991, initial shrub heights and densities reflected decades of grazing pressure. Mean heights of515 woody plants (14 species) was 47 cm and densities on gravel bars averaged 10.7 plants/100m². After two seasons without livestock grazing, mean crown volumes of willows (Salix spp.) increased 550% inside of wild ungulate exclosures and 195% outside, black cottonwood (Populus trichocarpa) 773% inside and 808% outside, and thin-leaf alder (Almis incana) 1046% inside and 198% outside, respectively. Willows were significantly impeded (p<0.Ol) mule deer and Rocky Mountain elk, alder samples were too small to statistically test, and cottonwood was not significantly impeded. However, impacts by deer and elk may be exaggerated due to high densities and the ungulate density-dynamics unique within the 77 km² Starkey Experimental Forest big-game enclosure surrounding the study site. Establishment rates are low at this time, i.e., only 10% of previously suppressed willows produced catkins. Although in transects densities increased by 5 new woody plants/lOOm² (50m of streambank). Other non-anthropogenic factors influencing the recovery of shrubs, included beaver which removed mainstems from 20% of willows, 11% of thin-leaf alder, and 4% of black cottonwood, and active insect defoliation which was noted on 16% of willows, 7% of thin-leaf alder, and 0% of black cottonwood. Crude protein levels measured in willow and alder leaves was relatively high (16.1 to 16.3%) helping to explain their palatability and use by wild and domestic herbivores. Few studies have quantified biomass, structure and composition of headwater riparian ecosystems. Data such as this are important given their dominant roles in ecosystem biodiversity, and aquatic function. To document relatively intact forested headwater ripanan conditions in the Upper Grande Ronde Basin, the biomass, structure and composition along six headwater reaches was quantified. Sampling was done using a nested belt transect/plot arrangement along 500 meter reaches. Total aboveground biomass (TAGB) ranged from 203 to 261 Mg/ha, with overstory conifers contributing 101 to 177 Mg/ha. Living understory components (saplings, seedlings, shrubs, and herbs) comprised 5 to 18 Mg/ha (2 to 9% of TAGB), while forest floor detrital accumulations comprised 65 to 101 Mg/ha (29 to 42% of TAGB). Average shade per day for July, 1993 ranged between 53% and 75%, reducing the unshaded solar energy potential of 2390 Mj/day to between 680 and 1280 Mj/day striking each m² of stream surface. This baseline reference information can serve in multi-disciplined research, as well as, be a basis for long term studies of natural systems responding to changing climate and different resource management scenarios. Title: The ecology of riparian ecosystems of Northeast Oregon : shrub recovery at Meadow Creek and the structure and biomass of headwater Upper Grande Ronde ecosystems Author: Case, Richard L. Riparian ecosystems play numerous and essential roles related to the quality and flow of water, and food/habitat for fish, and varieties of wildlife. Due to lateral and linear linkages throughout the landscape, these zones influence the integrity of the terrestrial as well as the entire aquatic-riverine ecosystem. Since Euro-American settlement in the West, the structure and condition of many riparian ecosystems has been significantly altered. To provide tools and an ecological perspective related to riparian restoration and management, and to document late 20th century headwater riparian structure and biomass in the Upper Grande Ronde Basin, this research project was undertaken. At Meadow Creek, the response of riparian hardwood species to the termination of livestock grazing was quantified. Regression equations were developed to predict shrub biomass. Permanently marked hardwood plants were measured annually to quantify parameters of growth (height, crown area, mainstem diameter, number of stems, biomass). Permanent belt transects on gravel bars were utilized to quantify rates of shrub establishment. Elk/deer-proof exclosures allowed the quantification of the browsing influence of wild ungulates. In 1991, initial shrub heights and densities reflected decades of grazing pressure. Mean heights of515 woody plants (14 species) was 47 cm and densities on gravel bars averaged 10.7 plants/100m². After two seasons without livestock grazing, mean crown volumes of willows (Salix spp.) increased 550% inside of wild ungulate exclosures and 195% outside, black cottonwood (Populus trichocarpa) 773% inside and 808% outside, and thin-leaf alder (Almis incana) 1046% inside and 198% outside, respectively. Willows were significantly impeded (p<0.Ol) mule deer and Rocky Mountain elk, alder samples were too small to statistically test, and cottonwood was not significantly impeded. However, impacts by deer and elk may be exaggerated due to high densities and the ungulate density-dynamics unique within the 77 km² Starkey Experimental Forest big-game enclosure surrounding the study site. Establishment rates are low at this time, i.e., only 10% of previously suppressed willows produced catkins. Although in transects densities increased by 5 new woody plants/lOOm² (50m of streambank). Other non-anthropogenic factors influencing the recovery of shrubs, included beaver which removed mainstems from 20% of willows, 11% of thin-leaf alder, and 4% of black cottonwood, and active insect defoliation which was noted on 16% of willows, 7% of thin-leaf alder, and 0% of black cottonwood. Crude protein levels measured in willow and alder leaves was relatively high (16.1 to 16.3%) helping to explain their palatability and use by wild and domestic herbivores. Few studies have quantified biomass, structure and composition of headwater riparian ecosystems. Data such as this are important given their dominant roles in ecosystem biodiversity, and aquatic function. To document relatively intact forested headwater ripanan conditions in the Upper Grande Ronde Basin, the biomass, structure and composition along six headwater reaches was quantified. Sampling was done using a nested belt transect/plot arrangement along 500 meter reaches. Total aboveground biomass (TAGB) ranged from 203 to 261 Mg/ha, with overstory conifers contributing 101 to 177 Mg/ha. Living understory components (saplings, seedlings, shrubs, and herbs) comprised 5 to 18 Mg/ha (2 to 9% of TAGB), while forest floor detrital accumulations comprised 65 to 101 Mg/ha (29 to 42% of TAGB). Average shade per day for July, 1993 ranged between 53% and 75%, reducing the unshaded solar energy potential of 2390 Mj/day to between 680 and 1280 Mj/day striking each m² of stream surface. This baseline reference information can serve in multi-disciplined research, as well as, be a basis for long term studies of natural systems responding to changing climate and different resource management scenarios. Close

• 2747. [Article] Juvenile survival and birth-site selection of Rocky Mountain elk in northeastern Oregon

  With declining populations and low calf recruitment in northeastern Oregon, much interest has been generated to study the survival rates and causes of mortality of Rocky Mountain elk (Cervus elaphus nelsoni). ...

  Citation × Citation Citation Abstract Copy Title: Juvenile survival and birth-site selection of Rocky Mountain elk in northeastern Oregon Author: Rearden, Spencer N. With declining populations and low calf recruitment in northeastern Oregon, much interest has been generated to study the survival rates and causes of mortality of Rocky Mountain elk (Cervus elaphus nelsoni). I investigated the causes of elk calf mortality and the effects of predation risk on birth-site selection by cow elk. Cow elk were captured in March of 2002-2004 to determine their pregnancy status and condition (percent fat, mass, and age). Pregnant cows had temperature-sensitive vaginal implant transmitters inserted that were expelled at parturition in order to locate newborn calves and birth sites later during the calving season. Elk calves were captured in two adjacent study areas, the Wenaha and Sled Springs, with the use of vaginal implant transmitters, a helicopter and net gun, and ground searching. A total of 222 calves were captured during the spring and summer of 2002-2004. Calves were sexed, aged, weighed, and fitted with radio-transmitting collars that had mortality sensors integrated into the circuitry. Monitoring of the radio-collared calves was done from fixed-wing aircraft. Calf collars in mortality mode were located on foot to investigate and determine cause of death. Predator-related mortalities were marked with a global positioning unit and the most likely spot where the calf was killed was flagged. I took microhabitat measurements that described horizontal and vertical cover at each birth and predation site and 2 paired random sites. During the summers of 2003-2004, I measured 49 birth sites and 62 predation sites along with 2 paired random sites for each. Using a geographic information system (GIS) I obtained slope and aspect for each site. I also used GIS to obtain macrohabitat data on birth, predation, and 80 random sites (for comparison). For each site, I measured the percent canopy cover and the amount of forest edge within a 250, 500, and 1,000 m radius circle. In addition, I also obtained the distance from each site to the nearest edge. I found differences in annual survival rates between the two adjacent study areas, with calves in Wenaha having lower survival (0.26; 95% CI = 0.15 to 0.42) rates than calves in Sled Springs (0.52; 95% CI = 0.37 to 0.56). Overall, predation was the main proximate cause of death. In 2003-2004, cougars (Felis concolor) killed 54% and 35% of radio-collared calves in Wenaha and Sled Springs, respectively. Annual calf survival was influenced by birth date (13 -0.35; 95% CI = -0.64 to -0.06). Both birth date (13 = -0.25 3; 95% CI = -0.502 to -.0003) and birth weight (13 = 0.13; 95% CI = -0.14 to 0.39) influenced summer calf survival, with earlier and heavier-born calves having higher survival rates than late and light-born calves. I found no differences in annual survival rates between the sexes in this study. However, I did find differences in summer survival rates between the sexes depending on the area. In Wenaha, females (0.57; 95% CI = 0.42 to 0.72) had higher survival than males (0.42; 95% CI 0.27 to 0.59), and in Sled Springs, males (0.82; 95% CI = 0.66 to 0.91) had higher survival than females (0.46; 95% CI = 0.31 to 0.61). Preliminary analyses suggested that cow condition did not influence calf survival, nor was cow condition correlated with the estimated birth date and birth weight of calves. However, the analyses that examined the effects of cow condition on calf survival were preliminary and inconclusive due to small sample sizes. I found that birth-site selection of cow elk was influenced by predation risk at the microhabitat scale. Cow elk selected birth sites that had less horizontal cover (0.97 times the odds; 95% CI = 0.94 to 0.99) and more overhead density of vegetation (1.022 times the odds; 95% CI = 1.005 to 1.040) than paired-random sites. Although predation sites also had less horizontal cover (0.985 times the odds; 95% CI = 0.973 to 0.998) than random sites, birth sites had less horizontal cover (0.983 times the odds; 95% CI = 0.967 to 1.001) and more overhead density of vegetation (1.02 times the odds, 95% CI = 1.01 to 1.04) than predation sites. I found no evidence that cow elk were influenced by predation risk at the macrohabitat scale. Cow elk chose birth sites with less canopy cover than random sites within a 500 m-radius circle. Cow elk were likely more influenced by forage availability rather than predation risk when selecting a birth site at the macrohabitat scale. When birth sites were compared to predation sites at this scale, I found no differences, further suggesting that birth-site selection was not influenced by predation risk. Cow elk were likely selecting broad areas for parturition that had sufficient forage to meet high nutritional demands due to lactation. Within these areas, cow elk selected birth sites that had high visibility at the microhabitat scale, presumably to detect predators visually and to avoid predation on calves. Title: Juvenile survival and birth-site selection of Rocky Mountain elk in northeastern Oregon Author: Rearden, Spencer N. With declining populations and low calf recruitment in northeastern Oregon, much interest has been generated to study the survival rates and causes of mortality of Rocky Mountain elk (Cervus elaphus nelsoni). I investigated the causes of elk calf mortality and the effects of predation risk on birth-site selection by cow elk. Cow elk were captured in March of 2002-2004 to determine their pregnancy status and condition (percent fat, mass, and age). Pregnant cows had temperature-sensitive vaginal implant transmitters inserted that were expelled at parturition in order to locate newborn calves and birth sites later during the calving season. Elk calves were captured in two adjacent study areas, the Wenaha and Sled Springs, with the use of vaginal implant transmitters, a helicopter and net gun, and ground searching. A total of 222 calves were captured during the spring and summer of 2002-2004. Calves were sexed, aged, weighed, and fitted with radio-transmitting collars that had mortality sensors integrated into the circuitry. Monitoring of the radio-collared calves was done from fixed-wing aircraft. Calf collars in mortality mode were located on foot to investigate and determine cause of death. Predator-related mortalities were marked with a global positioning unit and the most likely spot where the calf was killed was flagged. I took microhabitat measurements that described horizontal and vertical cover at each birth and predation site and 2 paired random sites. During the summers of 2003-2004, I measured 49 birth sites and 62 predation sites along with 2 paired random sites for each. Using a geographic information system (GIS) I obtained slope and aspect for each site. I also used GIS to obtain macrohabitat data on birth, predation, and 80 random sites (for comparison). For each site, I measured the percent canopy cover and the amount of forest edge within a 250, 500, and 1,000 m radius circle. In addition, I also obtained the distance from each site to the nearest edge. I found differences in annual survival rates between the two adjacent study areas, with calves in Wenaha having lower survival (0.26; 95% CI = 0.15 to 0.42) rates than calves in Sled Springs (0.52; 95% CI = 0.37 to 0.56). Overall, predation was the main proximate cause of death. In 2003-2004, cougars (Felis concolor) killed 54% and 35% of radio-collared calves in Wenaha and Sled Springs, respectively. Annual calf survival was influenced by birth date (13 -0.35; 95% CI = -0.64 to -0.06). Both birth date (13 = -0.25 3; 95% CI = -0.502 to -.0003) and birth weight (13 = 0.13; 95% CI = -0.14 to 0.39) influenced summer calf survival, with earlier and heavier-born calves having higher survival rates than late and light-born calves. I found no differences in annual survival rates between the sexes in this study. However, I did find differences in summer survival rates between the sexes depending on the area. In Wenaha, females (0.57; 95% CI = 0.42 to 0.72) had higher survival than males (0.42; 95% CI 0.27 to 0.59), and in Sled Springs, males (0.82; 95% CI = 0.66 to 0.91) had higher survival than females (0.46; 95% CI = 0.31 to 0.61). Preliminary analyses suggested that cow condition did not influence calf survival, nor was cow condition correlated with the estimated birth date and birth weight of calves. However, the analyses that examined the effects of cow condition on calf survival were preliminary and inconclusive due to small sample sizes. I found that birth-site selection of cow elk was influenced by predation risk at the microhabitat scale. Cow elk selected birth sites that had less horizontal cover (0.97 times the odds; 95% CI = 0.94 to 0.99) and more overhead density of vegetation (1.022 times the odds; 95% CI = 1.005 to 1.040) than paired-random sites. Although predation sites also had less horizontal cover (0.985 times the odds; 95% CI = 0.973 to 0.998) than random sites, birth sites had less horizontal cover (0.983 times the odds; 95% CI = 0.967 to 1.001) and more overhead density of vegetation (1.02 times the odds, 95% CI = 1.01 to 1.04) than predation sites. I found no evidence that cow elk were influenced by predation risk at the macrohabitat scale. Cow elk chose birth sites with less canopy cover than random sites within a 500 m-radius circle. Cow elk were likely more influenced by forage availability rather than predation risk when selecting a birth site at the macrohabitat scale. When birth sites were compared to predation sites at this scale, I found no differences, further suggesting that birth-site selection was not influenced by predation risk. Cow elk were likely selecting broad areas for parturition that had sufficient forage to meet high nutritional demands due to lactation. Within these areas, cow elk selected birth sites that had high visibility at the microhabitat scale, presumably to detect predators visually and to avoid predation on calves. Close

• 2748. [Article] Seed and seedling ecology of Artemisia tridentata in a restoration context

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

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

• 2749. [Article] The physiology ecology and run diversity of adult Pacific lamprey, Entosphenus tridentatus, during the freshwater spawning migration

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

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

• 2750. [Article] Potential for dispersal of the non-native parasite Myxobolus cerebralis : qualitative risk assessments for the state of Alaska and the Willamette River Basin, Oregon

  First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations ...

  Citation × Citation Citation Abstract Copy Title: Potential for dispersal of the non-native parasite Myxobolus cerebralis : qualitative risk assessments for the state of Alaska and the Willamette River Basin, Oregon Author: Arsan, E. Leyla First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite introduction, have strengthened the process of science-based decision-making in aquatic animal health. In the case of M. cerebralis, it is necessary to use a risk assessment model with two unique segments that clearly address the distinct life stages and respective hosts of the parasite separately. The studies described examine the probability of M. cerebralis introduction and establishment for two regions: the state of Alaska, and the Willamette River basin, Oregon. The Alaska risk assessment was based on the assumption that the parasite did not already occur in the state. However, in the process of validating this assumption, we documented the first polymerase chain reaction (PCR) detection of the parasite in the state. The pathogen was identified in hatchery rainbow trout (Oncorhynchus mykiss) from the Anchorage area. Although this is the first detection of the parasite in Alaska, clinical whirling disease has never been documented in the state. To qualitatively assess the risk of further spread of M. cerebralis in Alaska, four potential routes of dissemination were examined: movement of fish by humans, natural dispersal (via migratory birds and stray anadromous salmon), recreational activities, and commercial seafood processing. This research indicates the most likely pathway for M. cerebralis transport in Alaska is human movement of fish. In the Willamette River basin, Oregon, introduction of M. cerebralis has already occurred, though establishment appears limited to a single private hatchery. Introduction in this region was considered the most likely to occur as a result of human movements of fish. Straying anadromous salmonids were also assessed and were present in higher numbers than predicted. However, they were not infected with the parasite, and thus the probability for introduction by this route is low. The probability of introduction of the parasite varies throughout the Willamette River basin. Areas with the highest probability for M. cerebralis introduction were identified as the Clackamas and Santiam River subbasins. The Clackamas River has already experienced an introduction of the parasite, has the largest concentration of hatcheries (state, federal, and private), has a popular sport fishery, and is the closest major tributary to the enormous piscivorous bird-populations in the Columbia River estuary. The Santiam subbasin has a popular sport fishery, received the highest number of stray fish in the Willamette River basin, and has the second largest concentration of hatcheries in the Willamette River basin. Unique from introduction, establishment of the parasite is dependent upon several environmental and biological factors including: water temperatures, spatial/temporal overlap of hosts, and the distribution and genetic composition of the parasite’s invertebrate host, Tubifex tubifex. The distribution, genetic composition and susceptibility of T. tubifex, were considered the most important factor in the ability of M. cerebralis to establish in both systems. Surveys of oligochaete populations were conducted in both study regions. In Alaska, T. tubifex was not detected from the southeast region and the apparent lack of appropriate tubificid hosts may prevent establishment in that part of the state. However, 4 lineages (I, III, IV, and VI) of the species were identified from southcentral Alaska. Lineage IV has not been previously been described in North America and its susceptibility to M. cerebralis was unknown. When lineage IV T. tubifex and 3 mixed-lineage (I, III, IV and VI) groups were exposed to M. cerebralis, only lineage III became infected under our experimental conditions. Thus, if the parasite were dispersed, conditions are appropriate for establishment and propagation of the parasite life cycle in southcentral Alaska, although detrimental effects on fish populations may be reduced as a result of the presence of non-susceptible lineages of T. tubifex. The probability of further establishment in this area is greatest in Ship Creek, where the abundance of susceptible T. tubifex, the presence of susceptible rainbow trout (Oncorhynchus mykiss), and the proximity to the known area of infection make conditions particularly appropriate. Similar to findings in Alaska, the Willamette River basin, Oregon also supports populations of susceptible T. tubifex. If the pathogen were introduced, probability of establishment is high in certain areas of the basin as all conditions are appropriate for propagation of the parasite life cycle. Tributaries to the mainstem Willamette River have the highest probability of establishment as these areas have the greatest numbers of susceptible T. tubifex. However, the abundance of resistant strains of T. tubifex could mitigate the effects of M. cerebralis if introduced. Management recommendations to reduce the likelihood of parasite dissemination are similar for Oregon and Alaska since human movement of fish and angler activities were considered the most likely routes of introduction for both regions. Based on this research, steps should also be taken to limit human movement of fish, whether by restricting carcass planting for stream enrichment in Oregon, or by prohibiting use of fish heads as bait in southcentral Alaska. The states should also allot resources to angler education and awareness of the effects of angler activity and recreation on dispersal of M. cerebralis. This could be done using a combination of brochures and signage at boat ramps describing how to prevent spread of aquatic nuisance species. Title: Potential for dispersal of the non-native parasite Myxobolus cerebralis : qualitative risk assessments for the state of Alaska and the Willamette River Basin, Oregon Author: Arsan, E. Leyla First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite introduction, have strengthened the process of science-based decision-making in aquatic animal health. In the case of M. cerebralis, it is necessary to use a risk assessment model with two unique segments that clearly address the distinct life stages and respective hosts of the parasite separately. The studies described examine the probability of M. cerebralis introduction and establishment for two regions: the state of Alaska, and the Willamette River basin, Oregon. The Alaska risk assessment was based on the assumption that the parasite did not already occur in the state. However, in the process of validating this assumption, we documented the first polymerase chain reaction (PCR) detection of the parasite in the state. The pathogen was identified in hatchery rainbow trout (Oncorhynchus mykiss) from the Anchorage area. Although this is the first detection of the parasite in Alaska, clinical whirling disease has never been documented in the state. To qualitatively assess the risk of further spread of M. cerebralis in Alaska, four potential routes of dissemination were examined: movement of fish by humans, natural dispersal (via migratory birds and stray anadromous salmon), recreational activities, and commercial seafood processing. This research indicates the most likely pathway for M. cerebralis transport in Alaska is human movement of fish. In the Willamette River basin, Oregon, introduction of M. cerebralis has already occurred, though establishment appears limited to a single private hatchery. Introduction in this region was considered the most likely to occur as a result of human movements of fish. Straying anadromous salmonids were also assessed and were present in higher numbers than predicted. However, they were not infected with the parasite, and thus the probability for introduction by this route is low. The probability of introduction of the parasite varies throughout the Willamette River basin. Areas with the highest probability for M. cerebralis introduction were identified as the Clackamas and Santiam River subbasins. The Clackamas River has already experienced an introduction of the parasite, has the largest concentration of hatcheries (state, federal, and private), has a popular sport fishery, and is the closest major tributary to the enormous piscivorous bird-populations in the Columbia River estuary. The Santiam subbasin has a popular sport fishery, received the highest number of stray fish in the Willamette River basin, and has the second largest concentration of hatcheries in the Willamette River basin. Unique from introduction, establishment of the parasite is dependent upon several environmental and biological factors including: water temperatures, spatial/temporal overlap of hosts, and the distribution and genetic composition of the parasite’s invertebrate host, Tubifex tubifex. The distribution, genetic composition and susceptibility of T. tubifex, were considered the most important factor in the ability of M. cerebralis to establish in both systems. Surveys of oligochaete populations were conducted in both study regions. In Alaska, T. tubifex was not detected from the southeast region and the apparent lack of appropriate tubificid hosts may prevent establishment in that part of the state. However, 4 lineages (I, III, IV, and VI) of the species were identified from southcentral Alaska. Lineage IV has not been previously been described in North America and its susceptibility to M. cerebralis was unknown. When lineage IV T. tubifex and 3 mixed-lineage (I, III, IV and VI) groups were exposed to M. cerebralis, only lineage III became infected under our experimental conditions. Thus, if the parasite were dispersed, conditions are appropriate for establishment and propagation of the parasite life cycle in southcentral Alaska, although detrimental effects on fish populations may be reduced as a result of the presence of non-susceptible lineages of T. tubifex. The probability of further establishment in this area is greatest in Ship Creek, where the abundance of susceptible T. tubifex, the presence of susceptible rainbow trout (Oncorhynchus mykiss), and the proximity to the known area of infection make conditions particularly appropriate. Similar to findings in Alaska, the Willamette River basin, Oregon also supports populations of susceptible T. tubifex. If the pathogen were introduced, probability of establishment is high in certain areas of the basin as all conditions are appropriate for propagation of the parasite life cycle. Tributaries to the mainstem Willamette River have the highest probability of establishment as these areas have the greatest numbers of susceptible T. tubifex. However, the abundance of resistant strains of T. tubifex could mitigate the effects of M. cerebralis if introduced. Management recommendations to reduce the likelihood of parasite dissemination are similar for Oregon and Alaska since human movement of fish and angler activities were considered the most likely routes of introduction for both regions. Based on this research, steps should also be taken to limit human movement of fish, whether by restricting carcass planting for stream enrichment in Oregon, or by prohibiting use of fish heads as bait in southcentral Alaska. The states should also allot resources to angler education and awareness of the effects of angler activity and recreation on dispersal of M. cerebralis. This could be done using a combination of brochures and signage at boat ramps describing how to prevent spread of aquatic nuisance species. Close