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• 7291. [Article] The Roles of Dietary Nitrate in Bone and the Gut in an Ovarian Hormone-deficient Rodent Model

  Osteoporosis is a common metabolic bone disease, affecting a third of women and a fifth of men over age 65. In the US, annual health care costs associated with osteoporosis are estimated to be over $20 ...

  Citation × Citation Citation Abstract Copy Title: The Roles of Dietary Nitrate in Bone and the Gut in an Ovarian Hormone-deficient Rodent Model Author: Conley, Melissa N. Osteoporosis is a common metabolic bone disease, affecting a third of women and a fifth of men over age 65. In the US, annual health care costs associated with osteoporosis are estimated to be over $20 billion. Osteoporosis is associated with increased fracture risk, which has been demonstrated to predict mortality rates and nursing home admittance. Altered bone remodeling, defined by excessive bone resorption and/or impaired bone formation, is a major risk factor for osteoporotic fracture. In menopause-induced ovarian hormone deficiency, bone resorption exceeds formation. Menopause-induced bone resorption is associated with a reduced bone mineral density (BMD), and there is a relationship between low BMD and increased fracture risk. Given the importance of bone remodeling and fracture risk, there have been significant efforts to understand the ability of dietary components to slow bone loss. Some observational studies report that fruit and vegetable consumption is associated with an increase in bone mineral content (BMC) and BMD. Dietary nitrates, present in high concentrations in leafy green vegetables, may serve as a dietary component that supports bone health. Vegetable intake accounts for ~80% of dietary nitrate consumption in the typical human diet. Dietary nitrates can be reduced to nitric oxide (NO) via non-enzymatic reduction by lingual bacteria and a variety of mammalian reductases through the nitrate-nitrite-NO pathway. There is evidence suggesting that strategies to increase NO bioavailability using organic nitrates (i.e., nitroglycerin) as an NO donor may decrease bone turnover and loss in ovariectomized (OVX) animals, which are animals that have had their ovaries surgically removed to induce a postmenopausal-like state, defined by diminished ovarian production of female hormones, particularly estrogen and progesterone. Some follow up trials in postmenopausal women have demonstrated similar results. Since non-enzymatic reduction of dietary nitrate can account for up to 50% of NO production, this provides a biologically plausible link between dietary nitrate and bone health and suggests that dietary nitrate, as an alternate NO donor, may offer efficacious means of decreasing bone loss in postmenopausal women. Here, using an in vivo approach, we examined the dose-response relationship between dietary nitrates and bone density, microarchitecture, and turnover in OVX rats. We show that dietary nitrates do not improve bone density, microarchitecture, or turnover. Further, dietary nitrate had no beneficial effect on mineral apposition rate, bone formation rate, or bone volume/tissue volume in OVX rats. Our novel findings demonstrate dietary nitrate does not slow ovx-induced bone loss. This knowledge clarified the relationship between a dietary compound found in large quantities in leafy greens and bone loss in an OVX model. As an exploratory component of this study, we used 16S rRNA gene sequencing to profile the composition of fecal microbiota associated with sham surgical controls, OVX, and nitrate-treated groups to evaluate the ability of OVX or dietary nitrate to modulate the gut microbiome in OVX mammals. While dietary nitrate did not alter the gut microbiome in the context of OVX, we did observe gut microbiome changes in structure and composition associated with OVX status and identified specific phylotypes whose abundance stratify sham and OVX rats, including Proteobacteria, Firmicutes, and Bacteroidetes. These results add to the growing body of evidence that there is an association between the gut microbiome and sex steroid deficiency. Our use of the OVX model also provided an important added opportunity to further our understanding of the tissue effects of sex steroid deficiency observed in menopause. While both progesterone and estrogen influence metabolism, most attention has been given to the effects of ovarian hormone deficiency. Complex interactions between estrogen and host metabolism suggest that tissues in addition to serum and urine must be examined to clarify the mechanistic underpinnings of ovarian hormone deficiency and associated disease risk. Insufficient data are available from tissue-based studies using NMR-based platforms in estrogen-deficient models. Metabolomic studies in OVX rats, a model for osteoporosis, and postmenopausal women have demonstrated major metabolic shifts in serum, plasma, and urine as a result of ovarian hormone deficiency. To our knowledge, metabolomics has not been used for investigating the metabolic phenotype observed in the postmenopausal colon. Metabolomic studies of ovarian hormone deficiency is limited to bone, adipose, skeletal muscle, serum, plasma, and urine. Further, while it is established that ovarian hormone deficiency causes metabolic dysregulation, and the gut is associated with metabolic diseases and bone metabolism, there is also limited information available on the effects of estrogen loss on both gut tissue and gut microbiota. In light of this and our observed gut microbiome differences in OVX rats, we evaluated the effects of OVX on the colon using a metabolomics approach. We found the OVX colon is characterized by elevated levels of antioxidants, such as taurine and hypotaurine, and osmolytes, such as glycerophospholine, glycine, and glutamate. These novel findings suggest alterations to the colonic transsulfuration and methylation pathways, and they are suggestive of hyperosmotic and oxidative stress in the OVX colon. Previous work has associated hyperosmotic and oxidative stress with inflammation and intestinal permeability. These processes may also be present in the OVX colon; however, we did not quantify either inflammation or intestinal permeability in the current body of work. This dissertation takes advantage of a postmenopausal osteoporosis animal model and integrative techniques, such as osteologic, immunological, metabonomic, microbiomic and bioinformatic methods, to evaluate different metrics of osteoporosis, including physiological determinants influencing the rate of bone loss and gut-associated changes in ovarian hormone deficiency. The central findings of this dissertation show that dietary nitrate does not slow bone loss in ovarian hormone deficiency-induced rat model of bone loss. Further, dietary nitrate does not appear to influence the gut microbiome in the context of OVX. This is important in furthering our understanding of the relationship between the consumption of this ubiquitous component of fruit and vegetables and bone health. We also demonstrate that OVX is associated with shifts in gut microbiome structure and composition. Finally, we show OVX influences the colon metabolic phenotype, inducing the upregulation of metabolites involved with hyperosmotic and oxidative stress. Since estrogen protects against oxidative stress in many other tissues, we hypothesize that ovarian hormone deficiency promotes oxidative and hyperosmotic stress in the colon, promoting intestinal permeability and elevating the inflammatory response. In response, the colonic transsulfuration and methylation pathways may adapt by upregulating osmolytes and antioxidants. However, the specific causative agents of oxidative stress cannot be derived from our current work. Further investigation of the role these metabolites and processes play in the development of inflammation and metabolic dysregulation will yield insights into the physiological effects of ovarian hormone deficiency in postmenopausal women, allowing for more informed diagnosis and treatment of susceptible individuals. Title: The Roles of Dietary Nitrate in Bone and the Gut in an Ovarian Hormone-deficient Rodent Model Author: Conley, Melissa N. Osteoporosis is a common metabolic bone disease, affecting a third of women and a fifth of men over age 65. In the US, annual health care costs associated with osteoporosis are estimated to be over $20 billion. Osteoporosis is associated with increased fracture risk, which has been demonstrated to predict mortality rates and nursing home admittance. Altered bone remodeling, defined by excessive bone resorption and/or impaired bone formation, is a major risk factor for osteoporotic fracture. In menopause-induced ovarian hormone deficiency, bone resorption exceeds formation. Menopause-induced bone resorption is associated with a reduced bone mineral density (BMD), and there is a relationship between low BMD and increased fracture risk. Given the importance of bone remodeling and fracture risk, there have been significant efforts to understand the ability of dietary components to slow bone loss. Some observational studies report that fruit and vegetable consumption is associated with an increase in bone mineral content (BMC) and BMD. Dietary nitrates, present in high concentrations in leafy green vegetables, may serve as a dietary component that supports bone health. Vegetable intake accounts for ~80% of dietary nitrate consumption in the typical human diet. Dietary nitrates can be reduced to nitric oxide (NO) via non-enzymatic reduction by lingual bacteria and a variety of mammalian reductases through the nitrate-nitrite-NO pathway. There is evidence suggesting that strategies to increase NO bioavailability using organic nitrates (i.e., nitroglycerin) as an NO donor may decrease bone turnover and loss in ovariectomized (OVX) animals, which are animals that have had their ovaries surgically removed to induce a postmenopausal-like state, defined by diminished ovarian production of female hormones, particularly estrogen and progesterone. Some follow up trials in postmenopausal women have demonstrated similar results. Since non-enzymatic reduction of dietary nitrate can account for up to 50% of NO production, this provides a biologically plausible link between dietary nitrate and bone health and suggests that dietary nitrate, as an alternate NO donor, may offer efficacious means of decreasing bone loss in postmenopausal women. Here, using an in vivo approach, we examined the dose-response relationship between dietary nitrates and bone density, microarchitecture, and turnover in OVX rats. We show that dietary nitrates do not improve bone density, microarchitecture, or turnover. Further, dietary nitrate had no beneficial effect on mineral apposition rate, bone formation rate, or bone volume/tissue volume in OVX rats. Our novel findings demonstrate dietary nitrate does not slow ovx-induced bone loss. This knowledge clarified the relationship between a dietary compound found in large quantities in leafy greens and bone loss in an OVX model. As an exploratory component of this study, we used 16S rRNA gene sequencing to profile the composition of fecal microbiota associated with sham surgical controls, OVX, and nitrate-treated groups to evaluate the ability of OVX or dietary nitrate to modulate the gut microbiome in OVX mammals. While dietary nitrate did not alter the gut microbiome in the context of OVX, we did observe gut microbiome changes in structure and composition associated with OVX status and identified specific phylotypes whose abundance stratify sham and OVX rats, including Proteobacteria, Firmicutes, and Bacteroidetes. These results add to the growing body of evidence that there is an association between the gut microbiome and sex steroid deficiency. Our use of the OVX model also provided an important added opportunity to further our understanding of the tissue effects of sex steroid deficiency observed in menopause. While both progesterone and estrogen influence metabolism, most attention has been given to the effects of ovarian hormone deficiency. Complex interactions between estrogen and host metabolism suggest that tissues in addition to serum and urine must be examined to clarify the mechanistic underpinnings of ovarian hormone deficiency and associated disease risk. Insufficient data are available from tissue-based studies using NMR-based platforms in estrogen-deficient models. Metabolomic studies in OVX rats, a model for osteoporosis, and postmenopausal women have demonstrated major metabolic shifts in serum, plasma, and urine as a result of ovarian hormone deficiency. To our knowledge, metabolomics has not been used for investigating the metabolic phenotype observed in the postmenopausal colon. Metabolomic studies of ovarian hormone deficiency is limited to bone, adipose, skeletal muscle, serum, plasma, and urine. Further, while it is established that ovarian hormone deficiency causes metabolic dysregulation, and the gut is associated with metabolic diseases and bone metabolism, there is also limited information available on the effects of estrogen loss on both gut tissue and gut microbiota. In light of this and our observed gut microbiome differences in OVX rats, we evaluated the effects of OVX on the colon using a metabolomics approach. We found the OVX colon is characterized by elevated levels of antioxidants, such as taurine and hypotaurine, and osmolytes, such as glycerophospholine, glycine, and glutamate. These novel findings suggest alterations to the colonic transsulfuration and methylation pathways, and they are suggestive of hyperosmotic and oxidative stress in the OVX colon. Previous work has associated hyperosmotic and oxidative stress with inflammation and intestinal permeability. These processes may also be present in the OVX colon; however, we did not quantify either inflammation or intestinal permeability in the current body of work. This dissertation takes advantage of a postmenopausal osteoporosis animal model and integrative techniques, such as osteologic, immunological, metabonomic, microbiomic and bioinformatic methods, to evaluate different metrics of osteoporosis, including physiological determinants influencing the rate of bone loss and gut-associated changes in ovarian hormone deficiency. The central findings of this dissertation show that dietary nitrate does not slow bone loss in ovarian hormone deficiency-induced rat model of bone loss. Further, dietary nitrate does not appear to influence the gut microbiome in the context of OVX. This is important in furthering our understanding of the relationship between the consumption of this ubiquitous component of fruit and vegetables and bone health. We also demonstrate that OVX is associated with shifts in gut microbiome structure and composition. Finally, we show OVX influences the colon metabolic phenotype, inducing the upregulation of metabolites involved with hyperosmotic and oxidative stress. Since estrogen protects against oxidative stress in many other tissues, we hypothesize that ovarian hormone deficiency promotes oxidative and hyperosmotic stress in the colon, promoting intestinal permeability and elevating the inflammatory response. In response, the colonic transsulfuration and methylation pathways may adapt by upregulating osmolytes and antioxidants. However, the specific causative agents of oxidative stress cannot be derived from our current work. Further investigation of the role these metabolites and processes play in the development of inflammation and metabolic dysregulation will yield insights into the physiological effects of ovarian hormone deficiency in postmenopausal women, allowing for more informed diagnosis and treatment of susceptible individuals. Close

• 7292. [Article] Physiological Responses of Loblolly Pine and Douglas-fir Seedlings from Various Provenances to Timing and Frequency of Drought Stress

  Drought is expected to increase in many parts of the world and has been shown to affect tree physiology and growth, with seedlings being particularly vulnerable. Seedling drought responses are often species ...

  Citation × Citation Citation Abstract Copy Title: Physiological Responses of Loblolly Pine and Douglas-fir Seedlings from Various Provenances to Timing and Frequency of Drought Stress Author: Mosel, Jamie E. Drought is expected to increase in many parts of the world and has been shown to affect tree physiology and growth, with seedlings being particularly vulnerable. Seedling drought responses are often species dependent, and even within species different populations may demonstrate a spectrum of responses to drought, from susceptibility to resistance. As both loblolly pine (Pinus taeda) and Douglas-fir (Pseudotsuga menziesii) have broad geographic ranges, they provide an opportunity to assess drought resistances of provenances associated with a variety of site climate conditions across their ranges. Furthermore, while studies of singular drought events have revealed important information about seedling stress responses, it has been shown that drought may impart effects even following the release from drought. In some cases, effects of drought exposure can be detrimental or lethal; however, exposure to non-lethal drought may also lead to drought acclimation, which could potentially enhance seedling functioning under subsequent droughts. This potential phenotypic plasticity, i.e. the extent to which a seedling can acclimate to drought conditions, may vary across species and across provenances within a species. This study used physiological (electron transport rate, fluorescence, and water potentials) and growth (biomass accumulation and height increment) responses for two goals: 1) to assess the drought resistances of three provenances of loblolly pine and three provenances of Douglas-fir associated with varying site climate conditions, and 2) to investigate whether previous exposure to a drought results in acclimation to a second drought. We hypothesized that: 1) drought responses would differ among the provenances in accordance with associated site climate conditions (i.e., provenances associated with mesic site climates as characterized by low climatic moisture deficit and high mean annual precipitation would be drought susceptible, and more xeric site climates as characterized by high climatic moisture deficit and low mean annual precipitation would be more drought resistant) as evidenced by physiological measures of electron transport rate, fluorescence, water potentials and growth; and 2) previous exposure to drought would result in acclimation to drought as evidenced by maintenance of physiological function (i.e., higher levels of electron transport and fluorescence) in previously drought exposed seedlings compared to previously unexposed seedlings. We also hypothesized that levels of acclimation would vary among provenances. The study yielded some evidence to support the first hypothesis regarding provenance differences in drought resistances in both species. Provenance drought resistances conformed largely to expectations, though differences were less than expected. In loblolly pine, although not statistically significant, during the second drought there was a pattern of lower maximum electron transport rates, which appeared sooner in the more mesic provenance than in the other two provenances. There were also provenance differences in seedling heights, with the most xeric of the three provenances being shorter at the beginning and the end of the study. In Douglas-fir, there were significant differences in provenance and in the interaction of treatment and provenance for maximum electron rates and fluorescence. Dark-adapted fluorescence was lower in the Coos Bay (mesic site climate) provenance during drought than in the Cascades (mesic site climate) and New Mexico (xeric site climate) provenances. The New Mexico provenance showed the least differences in fluorescence between droughted and watered treatments. The study also yielded some evidence to support the second hypothesis regarding drought acclimation in both species and among provenances. During the second drought, there was a pattern of higher maximum electron transport rates and fluorescence in previously drought exposed seedlings as compared to seedlings previously unexposed to drought. This difference was significant in the mesic provenance (North Carolina) of loblolly pine, with maximum electron transport rates significantly higher in the previously drought exposed treatment compared to the newly exposed treatment during and following the second drought. Patterns of lower electron transport rates in seedlings previously unexposed to drought compared to seedlings previously exposed to drought also appeared in Douglas-fir during the second drought, though not with statistical significance. However, the most xeric provenance showed the reverse pattern during and following the second drought, with lower maximum electron transport rates in the previously drought exposed treatment compared to the treatment previously unexposed to drought. Chlorophyll fluorescence values were significantly higher during the second drought in the previously droughted treatments compared to newly drought-exposed treatments in some provenances of loblolly pine and Douglas-fir. Lastly, seedlings exposed to an early drought had significantly lower final heights than seedlings unexposed to an early drought in both species, although the differences were greater in loblolly pine than Douglas-fir. It may be that growth acclimation, especially in the form of height reductions, influenced physiological responses during a second drought. Further studies are necessary to provide more conclusive evidence in support or against the two hypotheses. Nonetheless, this study provides valuable information on the drought responses of young, greenhouse-grown seedlings of two species that are widespread in North America and that are economically important throughout the world. Further studies in a wider range of age classes, incorporating field studies or more natural settings, may help better predict plant responses in the face of changing climate. Title: Physiological Responses of Loblolly Pine and Douglas-fir Seedlings from Various Provenances to Timing and Frequency of Drought Stress Author: Mosel, Jamie E. Drought is expected to increase in many parts of the world and has been shown to affect tree physiology and growth, with seedlings being particularly vulnerable. Seedling drought responses are often species dependent, and even within species different populations may demonstrate a spectrum of responses to drought, from susceptibility to resistance. As both loblolly pine (Pinus taeda) and Douglas-fir (Pseudotsuga menziesii) have broad geographic ranges, they provide an opportunity to assess drought resistances of provenances associated with a variety of site climate conditions across their ranges. Furthermore, while studies of singular drought events have revealed important information about seedling stress responses, it has been shown that drought may impart effects even following the release from drought. In some cases, effects of drought exposure can be detrimental or lethal; however, exposure to non-lethal drought may also lead to drought acclimation, which could potentially enhance seedling functioning under subsequent droughts. This potential phenotypic plasticity, i.e. the extent to which a seedling can acclimate to drought conditions, may vary across species and across provenances within a species. This study used physiological (electron transport rate, fluorescence, and water potentials) and growth (biomass accumulation and height increment) responses for two goals: 1) to assess the drought resistances of three provenances of loblolly pine and three provenances of Douglas-fir associated with varying site climate conditions, and 2) to investigate whether previous exposure to a drought results in acclimation to a second drought. We hypothesized that: 1) drought responses would differ among the provenances in accordance with associated site climate conditions (i.e., provenances associated with mesic site climates as characterized by low climatic moisture deficit and high mean annual precipitation would be drought susceptible, and more xeric site climates as characterized by high climatic moisture deficit and low mean annual precipitation would be more drought resistant) as evidenced by physiological measures of electron transport rate, fluorescence, water potentials and growth; and 2) previous exposure to drought would result in acclimation to drought as evidenced by maintenance of physiological function (i.e., higher levels of electron transport and fluorescence) in previously drought exposed seedlings compared to previously unexposed seedlings. We also hypothesized that levels of acclimation would vary among provenances. The study yielded some evidence to support the first hypothesis regarding provenance differences in drought resistances in both species. Provenance drought resistances conformed largely to expectations, though differences were less than expected. In loblolly pine, although not statistically significant, during the second drought there was a pattern of lower maximum electron transport rates, which appeared sooner in the more mesic provenance than in the other two provenances. There were also provenance differences in seedling heights, with the most xeric of the three provenances being shorter at the beginning and the end of the study. In Douglas-fir, there were significant differences in provenance and in the interaction of treatment and provenance for maximum electron rates and fluorescence. Dark-adapted fluorescence was lower in the Coos Bay (mesic site climate) provenance during drought than in the Cascades (mesic site climate) and New Mexico (xeric site climate) provenances. The New Mexico provenance showed the least differences in fluorescence between droughted and watered treatments. The study also yielded some evidence to support the second hypothesis regarding drought acclimation in both species and among provenances. During the second drought, there was a pattern of higher maximum electron transport rates and fluorescence in previously drought exposed seedlings as compared to seedlings previously unexposed to drought. This difference was significant in the mesic provenance (North Carolina) of loblolly pine, with maximum electron transport rates significantly higher in the previously drought exposed treatment compared to the newly exposed treatment during and following the second drought. Patterns of lower electron transport rates in seedlings previously unexposed to drought compared to seedlings previously exposed to drought also appeared in Douglas-fir during the second drought, though not with statistical significance. However, the most xeric provenance showed the reverse pattern during and following the second drought, with lower maximum electron transport rates in the previously drought exposed treatment compared to the treatment previously unexposed to drought. Chlorophyll fluorescence values were significantly higher during the second drought in the previously droughted treatments compared to newly drought-exposed treatments in some provenances of loblolly pine and Douglas-fir. Lastly, seedlings exposed to an early drought had significantly lower final heights than seedlings unexposed to an early drought in both species, although the differences were greater in loblolly pine than Douglas-fir. It may be that growth acclimation, especially in the form of height reductions, influenced physiological responses during a second drought. Further studies are necessary to provide more conclusive evidence in support or against the two hypotheses. Nonetheless, this study provides valuable information on the drought responses of young, greenhouse-grown seedlings of two species that are widespread in North America and that are economically important throughout the world. Further studies in a wider range of age classes, incorporating field studies or more natural settings, may help better predict plant responses in the face of changing climate. Close

• 7293. [Article] Northern fur seal reproductive rates and early maternal care

  The majority of the world's breeding population of northern fur seals (Callorhinus ursinus) is found on the Pribilof Islands (St. Paul and St. George) in the Bering Sea, Alaska. Pup production on these ...

  Citation × Citation Citation Abstract Copy Title: Northern fur seal reproductive rates and early maternal care Author: Kunisch, E. (Erin) The majority of the world's breeding population of northern fur seals (Callorhinus ursinus) is found on the Pribilof Islands (St. Paul and St. George) in the Bering Sea, Alaska. Pup production on these islands experienced an irregular but overall decline since the early 1970's. Between 1998 and 2010, pup production declined precipitously at an annual rate of 4.9% on the Pribilof Islands, and 5.5% on St. Paul Island. Specific reasons for this decline remain unknown, and contemporary estimates for many vital rate parameters including reproductive rates are unavailable. This study determined a contemporary estimate of natality and fertility rates, as well as reproductive timing on the Polovina Cliffs rookery of St. Paul Island during the 2008 (30 June-31 August) and 2009 (1 July-25 August) breeding seasons. Natality rate (defined as the number of pups born divided by the number of reproductively mature females) was determined from visual observations of parturition or associated maternal behavior in 208 and 217 individually marked females (via flipper tags) in 2008 and 2009, respectively. Data yielded observed natality estimates of 0.79 in 2008 and 0.88 in 2009. The fertility rate (defined as the number of pups born divided by the total number of females present, irrespective of reproductive maturity/age) was determined for the 2008 breeding season only. This ratio of total pup to female counts was derived from adjusted daily cross-sectional counts conducted through the breeding season. Maximum pup and female counts were derived as asymptotes of sigmoid growth models fitted to corrected daily counts. Live pup counts were corrected for mortalities by estimates of cumulative pup mortalities. Daily counts of females present in the rookery were corrected for reduced detection probabilities resulting from increased maternal foraging trip durations through the season, typical of attendance patterns associated with colonial, income breeders. Daily detection probabilities for individually marked females were generated from Cormack-Jolly-Seber (CJS) open population models using maximum likelihood estimators (MLE) in Program MARK. Multiple a priori models accounting for the effects of possible covariates on detection probabilities were evaluated in an information-theoretic approach using Akaike's Information Criterion (AIC) and AICc model weights. Data yielded a minimum fertility rate estimate of 0.60 in 2008. Detection probabilities derived from the top CJS model for dual flipper-tagged females only were used to adjust the daily cross-section counts of all (marked and unmarked) females. Therefore, the actual fertility rate is probably higher than the estimate presented here, which should be regarded as the lowest likely value for 2008. However, AICc model weights also demonstrated the absence of density effects on detection probability estimates. This supports the applicability of marked female-based detection probabilities for correcting cross-sectional counts of all females and further suggests that the actual fertility estimate likely does not differ much from the presented estimate. Median dates of birth were calculated as the date closest to 50% of modeled corrected pup count asymptotes, yielding median dates of 17 July in 2008 and 15 July in 2009. Pregnant females are highly consistent in their arrival dates, with parturition occurring approximately 1 day after arrival. Median observed dates of arrival from individually marked females resulted in dates of 16 July in 2008 and 15 July in 2009. These dates occurred 5 to 13 days later than historic reports from 1951 through 1995. With median arrival dates 1 day prior to parturition, the observed match between birth dates derived from pup counts and from observed arrival dates of marked females supports the finding of a contemporary delay in the timing of parturition. Median arrival derived as the date closest to 50% of the asymptote from corrected and modeled female counts yielded 13 July in 2008. This earlier data is likely an effect of the inclusion of immature and nulli-parous females. In a subset of 62 females with pregnancy confirmed through a trans-rectal ultrasonography procedure in November 2007 and 29 females in 2008, the return rate for the following reproductive season was 0.92 and 0.76, respectively. In 2008, the return and natality rate was measured by radiotelemetry data, detected from females outfitted with VHF-radio transmitter. In 2009 both rates were determined by observational data. Observed natality rates for returned females of a known pregnancy status were 0.95 in 2008 and 0.96 in 2009. Radiotelemetry data from 76 females was analyzed for early maternal attendance patterns (duration and ratio of presences and absences) in 2008. The mean date of detected return was 18 July. The mean duration of the perinatal period was 7.5 days (+/- 1.3 SD). Excluding the perinatal period, the mean duration of presence on shore for the first five visits was 1.47 days (+/- 0.21 SD). The mean duration of absence at sea for the first five trips was 7.07 days (+/- 0.42 SD). Results presented from this study do not provide any direct evidence of a contemporary reduction in natality or fertility rates in northern fur seals. Since observed rates were comparably high and consistent between 2008 and 2009, it is unlikely that reduced natality rates are contributing to the current population trajectory. Attendance patterns do not provide any evidence of increased maternal foraging effort or secondarily, reduced prey availability. Interestingly, median pupping dates were found to occur significantly later than historical estimates. Potential reasons for this shift could be an increase in younger females within the reproductive female population at this rookery, or a shift in the timing of ocean climate conditions and peak prey availability during the breeding season. Title: Northern fur seal reproductive rates and early maternal care Author: Kunisch, E. (Erin) The majority of the world's breeding population of northern fur seals (Callorhinus ursinus) is found on the Pribilof Islands (St. Paul and St. George) in the Bering Sea, Alaska. Pup production on these islands experienced an irregular but overall decline since the early 1970's. Between 1998 and 2010, pup production declined precipitously at an annual rate of 4.9% on the Pribilof Islands, and 5.5% on St. Paul Island. Specific reasons for this decline remain unknown, and contemporary estimates for many vital rate parameters including reproductive rates are unavailable. This study determined a contemporary estimate of natality and fertility rates, as well as reproductive timing on the Polovina Cliffs rookery of St. Paul Island during the 2008 (30 June-31 August) and 2009 (1 July-25 August) breeding seasons. Natality rate (defined as the number of pups born divided by the number of reproductively mature females) was determined from visual observations of parturition or associated maternal behavior in 208 and 217 individually marked females (via flipper tags) in 2008 and 2009, respectively. Data yielded observed natality estimates of 0.79 in 2008 and 0.88 in 2009. The fertility rate (defined as the number of pups born divided by the total number of females present, irrespective of reproductive maturity/age) was determined for the 2008 breeding season only. This ratio of total pup to female counts was derived from adjusted daily cross-sectional counts conducted through the breeding season. Maximum pup and female counts were derived as asymptotes of sigmoid growth models fitted to corrected daily counts. Live pup counts were corrected for mortalities by estimates of cumulative pup mortalities. Daily counts of females present in the rookery were corrected for reduced detection probabilities resulting from increased maternal foraging trip durations through the season, typical of attendance patterns associated with colonial, income breeders. Daily detection probabilities for individually marked females were generated from Cormack-Jolly-Seber (CJS) open population models using maximum likelihood estimators (MLE) in Program MARK. Multiple a priori models accounting for the effects of possible covariates on detection probabilities were evaluated in an information-theoretic approach using Akaike's Information Criterion (AIC) and AICc model weights. Data yielded a minimum fertility rate estimate of 0.60 in 2008. Detection probabilities derived from the top CJS model for dual flipper-tagged females only were used to adjust the daily cross-section counts of all (marked and unmarked) females. Therefore, the actual fertility rate is probably higher than the estimate presented here, which should be regarded as the lowest likely value for 2008. However, AICc model weights also demonstrated the absence of density effects on detection probability estimates. This supports the applicability of marked female-based detection probabilities for correcting cross-sectional counts of all females and further suggests that the actual fertility estimate likely does not differ much from the presented estimate. Median dates of birth were calculated as the date closest to 50% of modeled corrected pup count asymptotes, yielding median dates of 17 July in 2008 and 15 July in 2009. Pregnant females are highly consistent in their arrival dates, with parturition occurring approximately 1 day after arrival. Median observed dates of arrival from individually marked females resulted in dates of 16 July in 2008 and 15 July in 2009. These dates occurred 5 to 13 days later than historic reports from 1951 through 1995. With median arrival dates 1 day prior to parturition, the observed match between birth dates derived from pup counts and from observed arrival dates of marked females supports the finding of a contemporary delay in the timing of parturition. Median arrival derived as the date closest to 50% of the asymptote from corrected and modeled female counts yielded 13 July in 2008. This earlier data is likely an effect of the inclusion of immature and nulli-parous females. In a subset of 62 females with pregnancy confirmed through a trans-rectal ultrasonography procedure in November 2007 and 29 females in 2008, the return rate for the following reproductive season was 0.92 and 0.76, respectively. In 2008, the return and natality rate was measured by radiotelemetry data, detected from females outfitted with VHF-radio transmitter. In 2009 both rates were determined by observational data. Observed natality rates for returned females of a known pregnancy status were 0.95 in 2008 and 0.96 in 2009. Radiotelemetry data from 76 females was analyzed for early maternal attendance patterns (duration and ratio of presences and absences) in 2008. The mean date of detected return was 18 July. The mean duration of the perinatal period was 7.5 days (+/- 1.3 SD). Excluding the perinatal period, the mean duration of presence on shore for the first five visits was 1.47 days (+/- 0.21 SD). The mean duration of absence at sea for the first five trips was 7.07 days (+/- 0.42 SD). Results presented from this study do not provide any direct evidence of a contemporary reduction in natality or fertility rates in northern fur seals. Since observed rates were comparably high and consistent between 2008 and 2009, it is unlikely that reduced natality rates are contributing to the current population trajectory. Attendance patterns do not provide any evidence of increased maternal foraging effort or secondarily, reduced prey availability. Interestingly, median pupping dates were found to occur significantly later than historical estimates. Potential reasons for this shift could be an increase in younger females within the reproductive female population at this rookery, or a shift in the timing of ocean climate conditions and peak prey availability during the breeding season. Close

• 7294. [Article] Wildlife Health in Managed Forests : Immunity and Infectious Diseases in Wild Rodents of Oregon

  With continual and worldwide human population growth, our impact on the natural environment expands and intensifies every day. We consume natural resources, burn fossil fuels, and release toxic compounds ...

  Citation × Citation Citation Abstract Copy Title: Wildlife Health in Managed Forests : Immunity and Infectious Diseases in Wild Rodents of Oregon Author: Hanselmann, Rhea With continual and worldwide human population growth, our impact on the natural environment expands and intensifies every day. We consume natural resources, burn fossil fuels, and release toxic compounds into the air, water, and earth. We build roads that fragment the landscape, construct new settlements, and develop agricultural lands in previously undisturbed areas. And, we introduce non-native species, which compete with and/or prey on native ones. Our actions change the composition of ecosystems by effacing natural environments and decimating plant and animal populations. We have reached a time of unprecedented anthropogenic environmental change. And, while we recognize, and work feverishly to mitigate, countless consequences of our actions, we still lack a profound understanding of just as many of the corollaries of the environmental changes we provoke. One thing we do know is that human-induced changes in environmental conditions can affect health – from individual organisms, to plant and animal populations, all the way to the level of the ecosystem. Yet, the mechanisms underlying such adverse health outcomes are only partially understood. For instance, we know that alterations in the structure of plant and animal communities, the distribution and demographics of populations, and the abundance of individuals can influence the emergence or re-emergence of infectious diseases. Which species are present in a community, where, when, and in what numbers can all determine the dynamics of pathogens, lead to disease outbreaks, and provide opportunities for spillover into new species. However, given the many environmental-, population-, and organism-level factors involved, and the complexity by which these variables interact, detecting and predicting the ultimate consequences for the health of animal, including human, populations remains difficult. Wild animals play important roles in numerous infectious disease cycles, many of which are shared with humans. Considering this and the well-documented effects that human activity can have on wildlife populations, studying the impacts of anthropogenic environmental change on health in wildlife is highly relevant. To understand how human-induced environmental changes affect wildlife health and to make predictions about potential regional or even global consequences for the dynamics of infectious diseases, however, we first need to understand patterns at a local scale. Here, I describe variation in immune function in captive and wild rodent species native to managed forests in northwestern Oregon, and examine how intensive forest management practices affect these and other physiological processes, and the prevalence of infectious diseases, in a large-scale field experiment. In Chapter 2 of this dissertation, I present baseline data on simple immune parameters in an iconic inhabitant of old-growth forests in the Pacific Northwest, the red tree vole (Arborimus longicaudus). I show that both body condition and age are important for immune defenses in this species. Translating these findings to wild populations leads me to predict that degradation of habitat may affect red tree voles not only at the population scale, as is currently the case, but that less obvious consequences for the health of individuals surviving in disturbed or suboptimal habitat are also possible. It is important, therefore, that efforts to conserve this species consider adverse effects of present forest management practices on red tree vole health, as potentially increased disease susceptibility could have detrimental outcomes for this species. In Chapters 3 and 4, I took advantage of a rare and large-scale experiment to test my predictions regarding the negative consequences of habitat degradation for individual animals in more ubiquitous rodent species known for their resilience to environmental disturbance. I investigated the effects of intensive forest management on stress, health, and immunity (Chapter 3), and on the prevalence of infectious diseases transmissible to humans (Chapter 4) in deer mice (Peromyscus maniculatus), Townsend chipmunks (Tamias townsendii), and creeping voles (Microtus oregoni) inhabiting managed forest plots in northwestern Oregon. The experimental design employed allowed me to test the effect of regionally representative forest management practices on health and disease outcomes with important implications for public health. In Chapter 3, I present results which suggest that intensive forest management can have complex, but highly context-dependent effects on the health of wild deer mice. Intensive forest management can shape animals’ condition and reproductive activity, increase levels of stress hormone, and stimulate some but depress other immune responses. However, deer mice are only able to respond to the extreme stressor of this disturbance when underlying environmental conditions are favorable. When inhabiting inherently harsh habitat, mice appear unable to cope with additional disturbance imposed by intensive forest management, and only the fittest mice survive. Finally, in Chapter 4, I identify moderate prevalence of two important and potentially fatal human infections in rodents inhabiting managed forests in northwestern Oregon. In deer mouse populations, Sin Nombre virus was clustered spatially, and prevalence varied between years. But, in the focus of highest infection, the proportion of infected mice, albeit low, appeared to increase with intensity of forest management. For Leptospirosis, I found a similar pattern in creeping voles, but did not observe an association between infection prevalence and forest management in deer mice or chipmunks. I conclude that forest management may drive infectious disease patterns, but that the direction and magnitude of such effects depends on the host-pathogen system. Taken together, my findings indicate that wild animal health can suffer from declines in habitat quality associated with forest management. For a near-threatened species such as the red tree vole, decreases in the availability of food and nesting habitat have the potential to change susceptibility to infection, which could facilitate disease invasion and further threaten populations. For wild animals that serve as reservoirs for human infections, especially abundant and apparently resilient species, impaired health can drive the dynamics of pathogens and increase the risk of transmission to humans and other animals. Although many more questions remain, my work contributes to our understanding of the effects of anthropogenic environmental change for wildlife and human health. Title: Wildlife Health in Managed Forests : Immunity and Infectious Diseases in Wild Rodents of Oregon Author: Hanselmann, Rhea With continual and worldwide human population growth, our impact on the natural environment expands and intensifies every day. We consume natural resources, burn fossil fuels, and release toxic compounds into the air, water, and earth. We build roads that fragment the landscape, construct new settlements, and develop agricultural lands in previously undisturbed areas. And, we introduce non-native species, which compete with and/or prey on native ones. Our actions change the composition of ecosystems by effacing natural environments and decimating plant and animal populations. We have reached a time of unprecedented anthropogenic environmental change. And, while we recognize, and work feverishly to mitigate, countless consequences of our actions, we still lack a profound understanding of just as many of the corollaries of the environmental changes we provoke. One thing we do know is that human-induced changes in environmental conditions can affect health – from individual organisms, to plant and animal populations, all the way to the level of the ecosystem. Yet, the mechanisms underlying such adverse health outcomes are only partially understood. For instance, we know that alterations in the structure of plant and animal communities, the distribution and demographics of populations, and the abundance of individuals can influence the emergence or re-emergence of infectious diseases. Which species are present in a community, where, when, and in what numbers can all determine the dynamics of pathogens, lead to disease outbreaks, and provide opportunities for spillover into new species. However, given the many environmental-, population-, and organism-level factors involved, and the complexity by which these variables interact, detecting and predicting the ultimate consequences for the health of animal, including human, populations remains difficult. Wild animals play important roles in numerous infectious disease cycles, many of which are shared with humans. Considering this and the well-documented effects that human activity can have on wildlife populations, studying the impacts of anthropogenic environmental change on health in wildlife is highly relevant. To understand how human-induced environmental changes affect wildlife health and to make predictions about potential regional or even global consequences for the dynamics of infectious diseases, however, we first need to understand patterns at a local scale. Here, I describe variation in immune function in captive and wild rodent species native to managed forests in northwestern Oregon, and examine how intensive forest management practices affect these and other physiological processes, and the prevalence of infectious diseases, in a large-scale field experiment. In Chapter 2 of this dissertation, I present baseline data on simple immune parameters in an iconic inhabitant of old-growth forests in the Pacific Northwest, the red tree vole (Arborimus longicaudus). I show that both body condition and age are important for immune defenses in this species. Translating these findings to wild populations leads me to predict that degradation of habitat may affect red tree voles not only at the population scale, as is currently the case, but that less obvious consequences for the health of individuals surviving in disturbed or suboptimal habitat are also possible. It is important, therefore, that efforts to conserve this species consider adverse effects of present forest management practices on red tree vole health, as potentially increased disease susceptibility could have detrimental outcomes for this species. In Chapters 3 and 4, I took advantage of a rare and large-scale experiment to test my predictions regarding the negative consequences of habitat degradation for individual animals in more ubiquitous rodent species known for their resilience to environmental disturbance. I investigated the effects of intensive forest management on stress, health, and immunity (Chapter 3), and on the prevalence of infectious diseases transmissible to humans (Chapter 4) in deer mice (Peromyscus maniculatus), Townsend chipmunks (Tamias townsendii), and creeping voles (Microtus oregoni) inhabiting managed forest plots in northwestern Oregon. The experimental design employed allowed me to test the effect of regionally representative forest management practices on health and disease outcomes with important implications for public health. In Chapter 3, I present results which suggest that intensive forest management can have complex, but highly context-dependent effects on the health of wild deer mice. Intensive forest management can shape animals’ condition and reproductive activity, increase levels of stress hormone, and stimulate some but depress other immune responses. However, deer mice are only able to respond to the extreme stressor of this disturbance when underlying environmental conditions are favorable. When inhabiting inherently harsh habitat, mice appear unable to cope with additional disturbance imposed by intensive forest management, and only the fittest mice survive. Finally, in Chapter 4, I identify moderate prevalence of two important and potentially fatal human infections in rodents inhabiting managed forests in northwestern Oregon. In deer mouse populations, Sin Nombre virus was clustered spatially, and prevalence varied between years. But, in the focus of highest infection, the proportion of infected mice, albeit low, appeared to increase with intensity of forest management. For Leptospirosis, I found a similar pattern in creeping voles, but did not observe an association between infection prevalence and forest management in deer mice or chipmunks. I conclude that forest management may drive infectious disease patterns, but that the direction and magnitude of such effects depends on the host-pathogen system. Taken together, my findings indicate that wild animal health can suffer from declines in habitat quality associated with forest management. For a near-threatened species such as the red tree vole, decreases in the availability of food and nesting habitat have the potential to change susceptibility to infection, which could facilitate disease invasion and further threaten populations. For wild animals that serve as reservoirs for human infections, especially abundant and apparently resilient species, impaired health can drive the dynamics of pathogens and increase the risk of transmission to humans and other animals. Although many more questions remain, my work contributes to our understanding of the effects of anthropogenic environmental change for wildlife and human health. Close

• 7295. [Article] Effects of Altered Habitats and Fishing Practices in Wind and Wave Farms

  Offshore renewable energy development (ORED) could induce local ecological changes, negatively affecting species of conservation interest. If well planned and coordinated, on the other hand, ORED could ...

  Citation × Citation Citation Abstract Copy Title: Effects of Altered Habitats and Fishing Practices in Wind and Wave Farms Author: Wilhelmsson, Dan Offshore renewable energy development (ORED) could induce local ecological changes, negatively affecting species of conservation interest. If well planned and coordinated, on the other hand, ORED could be beneficial to the marine environment in the region of device deployment in several respects. Because of the current scale and pace of offshore renewable energy development, interest is growing in the opportunities offered by the changes in fishing patterns that could result. Trawling, one of the most severe threats to the marine environment, particularly to fish and benthic invertebrate assemblages, will be prohibited or limited inside wind and wave farms. Areas of several square kilometres may therefore, in some important respects, resemble Marine Protected Areas; for areas that were previously trawled this exclusion could lead to average increases in biomass of motile organisms. Primary data from wind and wave farms are still scarce, but results to date from surveys targeting fish assemblages within offshore wind farms in Denmark, the Netherlands, and Sweden basically indicate either increased abundance of some fish species (e.g., sand eels (Ammodytidae), cod (Gadus morhua), whiting (Merlangius merlangus), sole (Solea solea)) or no effect compared to conditions before construction of the wind farm. Effects are likely to be most prominent for species that had been heavily exploited in the area prior to the wind or wave farm establishment. It is believed that a relatively large area of exclusion is required to enhance biodiversity and generate spill-over effects. Construction and deployment of artificial reefs (AR) in coastal waters is practiced worldwide to manage fisheries, mitigate damage to the environment, protect (i.e., from trawling) and facilitate the rehabilitation of certain habitats (e.g., spawning sites) or water bodies, or to increase the recreational value of an area (e.g., by providing opportunities for recreational diving and fishing). Unless animals are deterred by potential disturbances, such as noise, maintenance work, and electromagnetic fields from turbines, it is reasonable to expect offshore wind energy structures, and also foundations of some types of wave energy devices, to function as artificial reef modules and enhance local abundance of marine organisms, including commercially important fish and crustaceans. However, taxon- and age-specific responses of fishes to ARs vary greatly with AR design and position as well as by region and latitude. It can therefore be difficult to predict the structure of fish and crustacean assemblages associated with the submerged parts of wind and wave energy devices, as well as the radius of influence. Nevertheless, relatively recent studies targeting the potential for wind turbines and wave energy foundations to aggregate fish and motile invertebrates in Sweden, the Netherlands, Belgium, and Denmark suggest that densities of a number of fish and decapod species increase with proximity to these structures. Another category of artificial habitat is a Fish Aggregation Device (FAD), a floating structure deliberately placed on the surface or suspended in the water column to attract fish and enhance fishing efficiency. FADs are widely used in Asia and the western Indian Ocean. It has been suggested that floating offshore energy devices may function as FADs for pelagic fish, which could provide additional opportunities for fisheries management. Both ARs and FADs can have negative environmental and social effects if not properly planned and/or used. If ARs only aggregate fish from surrounding areas and do not contribute to added production, enhanced fishing efficiency in the AR area may aggravate overfishing if the new circumstances are not managed with caution. Similarly, increasing catchability, the main purpose of an FAD, may exacerbate the problem of overfishing on commercial species that are already at risk. ARs can also give rise to conflicts over user rights among fisher groups, and between recreational divers and fishers. Further, densities of benthic prey items have been shown to decrease with proximity to ARs due to predation by fish residing on the structures. FADs have been suggested as potential “ecological traps,” meaning that their presence could lure fish into remaining near the structures under non-optimal local feeding conditions, affecting physical condition and growth. Artificial structures may also provide habitats suitable for establishment of non-indigenous species; deployment of clusters of artificial structures may facilitate the establishment of new taxa in the recipient region by providing “beach heads” and stepping-stones. Non-indigenous sessile invertebrates have already been recorded at wind farms in the North Sea and the Baltic Sea. A range of design and location factors may influence the fish community structure on artificial reefs, such as height, size, inclination, protuberance, surface structure, void space and number of interior hollows, shade effects, distance between modules, isolation, and composition of the surrounding seabed. Research is underway to evaluate species-specific habitat preferences in the design of offshore energy foundations to optimize biomass of desired species, or alternatively, minimize artificial reef effects where desired. For example, in an experiment with wave energy foundations on the west coast of Sweden the potential for enhancing the abundance of associated fish and crustaceans through low-cost manipulations of the structural complexity of foundations was examined. Additional experiments will provide further guidance on the influence of different designs of foundations on commercially important fish and shellfish. This presentation will focus on the potential influence of offshore wind and wave farms on fish and commercially important crustaceans. The uncertainties with regard to positive and negative effects of on benthic and pelagic assemblages and specific species will also be discussed. The presentation will draw on results from a number of field studies and experiments conducted in offshore wind and wave farms, as well as on secondary literature on the influence of differently designed artificial habitats on benthic fauna. Title: Effects of Altered Habitats and Fishing Practices in Wind and Wave Farms Author: Wilhelmsson, Dan Offshore renewable energy development (ORED) could induce local ecological changes, negatively affecting species of conservation interest. If well planned and coordinated, on the other hand, ORED could be beneficial to the marine environment in the region of device deployment in several respects. Because of the current scale and pace of offshore renewable energy development, interest is growing in the opportunities offered by the changes in fishing patterns that could result. Trawling, one of the most severe threats to the marine environment, particularly to fish and benthic invertebrate assemblages, will be prohibited or limited inside wind and wave farms. Areas of several square kilometres may therefore, in some important respects, resemble Marine Protected Areas; for areas that were previously trawled this exclusion could lead to average increases in biomass of motile organisms. Primary data from wind and wave farms are still scarce, but results to date from surveys targeting fish assemblages within offshore wind farms in Denmark, the Netherlands, and Sweden basically indicate either increased abundance of some fish species (e.g., sand eels (Ammodytidae), cod (Gadus morhua), whiting (Merlangius merlangus), sole (Solea solea)) or no effect compared to conditions before construction of the wind farm. Effects are likely to be most prominent for species that had been heavily exploited in the area prior to the wind or wave farm establishment. It is believed that a relatively large area of exclusion is required to enhance biodiversity and generate spill-over effects. Construction and deployment of artificial reefs (AR) in coastal waters is practiced worldwide to manage fisheries, mitigate damage to the environment, protect (i.e., from trawling) and facilitate the rehabilitation of certain habitats (e.g., spawning sites) or water bodies, or to increase the recreational value of an area (e.g., by providing opportunities for recreational diving and fishing). Unless animals are deterred by potential disturbances, such as noise, maintenance work, and electromagnetic fields from turbines, it is reasonable to expect offshore wind energy structures, and also foundations of some types of wave energy devices, to function as artificial reef modules and enhance local abundance of marine organisms, including commercially important fish and crustaceans. However, taxon- and age-specific responses of fishes to ARs vary greatly with AR design and position as well as by region and latitude. It can therefore be difficult to predict the structure of fish and crustacean assemblages associated with the submerged parts of wind and wave energy devices, as well as the radius of influence. Nevertheless, relatively recent studies targeting the potential for wind turbines and wave energy foundations to aggregate fish and motile invertebrates in Sweden, the Netherlands, Belgium, and Denmark suggest that densities of a number of fish and decapod species increase with proximity to these structures. Another category of artificial habitat is a Fish Aggregation Device (FAD), a floating structure deliberately placed on the surface or suspended in the water column to attract fish and enhance fishing efficiency. FADs are widely used in Asia and the western Indian Ocean. It has been suggested that floating offshore energy devices may function as FADs for pelagic fish, which could provide additional opportunities for fisheries management. Both ARs and FADs can have negative environmental and social effects if not properly planned and/or used. If ARs only aggregate fish from surrounding areas and do not contribute to added production, enhanced fishing efficiency in the AR area may aggravate overfishing if the new circumstances are not managed with caution. Similarly, increasing catchability, the main purpose of an FAD, may exacerbate the problem of overfishing on commercial species that are already at risk. ARs can also give rise to conflicts over user rights among fisher groups, and between recreational divers and fishers. Further, densities of benthic prey items have been shown to decrease with proximity to ARs due to predation by fish residing on the structures. FADs have been suggested as potential “ecological traps,” meaning that their presence could lure fish into remaining near the structures under non-optimal local feeding conditions, affecting physical condition and growth. Artificial structures may also provide habitats suitable for establishment of non-indigenous species; deployment of clusters of artificial structures may facilitate the establishment of new taxa in the recipient region by providing “beach heads” and stepping-stones. Non-indigenous sessile invertebrates have already been recorded at wind farms in the North Sea and the Baltic Sea. A range of design and location factors may influence the fish community structure on artificial reefs, such as height, size, inclination, protuberance, surface structure, void space and number of interior hollows, shade effects, distance between modules, isolation, and composition of the surrounding seabed. Research is underway to evaluate species-specific habitat preferences in the design of offshore energy foundations to optimize biomass of desired species, or alternatively, minimize artificial reef effects where desired. For example, in an experiment with wave energy foundations on the west coast of Sweden the potential for enhancing the abundance of associated fish and crustaceans through low-cost manipulations of the structural complexity of foundations was examined. Additional experiments will provide further guidance on the influence of different designs of foundations on commercially important fish and shellfish. This presentation will focus on the potential influence of offshore wind and wave farms on fish and commercially important crustaceans. The uncertainties with regard to positive and negative effects of on benthic and pelagic assemblages and specific species will also be discussed. The presentation will draw on results from a number of field studies and experiments conducted in offshore wind and wave farms, as well as on secondary literature on the influence of differently designed artificial habitats on benthic fauna. Close

• 7296. [Article] Breeding ecology and nest site selection of Kittlitz's murrelets on Kodiak Island, Alaska

  The Kittlitz's murrelet (Brachyramphus brevirostris) is a rare member of the seabird family Alcidae that breeds in coastal areas of Alaska and Beringian Russia. The species belongs to the genus Brachyramphus, ...

  Citation × Citation Citation Abstract Copy Title: Breeding ecology and nest site selection of Kittlitz's murrelets on Kodiak Island, Alaska Author: Lawonn, Matthew James The Kittlitz's murrelet (Brachyramphus brevirostris) is a rare member of the seabird family Alcidae that breeds in coastal areas of Alaska and Beringian Russia. The species belongs to the genus Brachyramphus, an unusual seabird taxon in which all three extant species nest non-colonially, situating their nests up to 75 km inland from coastal marine waters. This nesting strategy is different from that of most seabird species, which tend to nest colonially on remote islands or sea cliffs, where terrestrial predators are generally absent or cannot easily access nests. Within the genus Brachyramphus, Kittlitz's murrelet is notable because a majority of the global population appears to nest on the surface of the ground in rocky alpine habitat near inland or tidewater glaciers, foraging in adjacent marine waters influenced by glacial outflows. The unusual nesting habits of Kittlitz's murrelet have made the study of its nesting ecology difficult, and gaps therefore exist in our understanding of the species' breeding biology. Kittlitz's murrelet populations have declined substantially in core areas of its range, causing the U. S. Fish and Wildlife Service to designate the species as a candidate for protection under the Endangered Species Act. A better understanding of Kittlitz's murrelet nesting ecology is crucial for determining potential causes of these declines and for future management of the species. To this end, I studied Kittlitz's murrelet breeding ecology and nest site selection during 2008-2011 on Kodiak Island, Alaska, in an unglaciated area that was recently found to have large numbers of accessible nests. I and my colleagues found 53 active Kittlitz's murrelet nests in inland scree-dominated habitats and placed remote, motion-sensing cameras at 33 nests. Adults exchanged incubation duties at the nest every 24 or 48 h, almost exclusively during early morning twilight. Following hatching of eggs, parents provisioned their single nestling with an average of 3.9 to 4.8 fish per day, depending on the year. Parental visits to the nest during chick-rearing occurred primarily after sunrise in the early to mid-morning hours, and during evening twilight. Fish were delivered singly to the chick, and Pacific sand lance (Ammodytes hexapterus), a high-lipid forage fish, accounted for about 92% of all identifiable chick meal deliveries. Chick growth rates were high relative to confamilial species, consistent with the high quality of chick diets; the logistic growth rate constant (K) was 0.291, greater than that for any other semi-precocial alcid. Chicks fledged an average of 24.8 d after hatching and asymptotic chick body mass averaged about 135.5 g, approximately 58% of adult body mass. Age at fledging, asymptotic chick body mass (% adult mass), and the number of meal deliveries required to fledge a chick were all lower than or as low as any other species of semi-precocial alcid. The average estimated nest survival rate during 2008-2011 was 0.093 (95% CI = 0.01–0.30), which is extremely low compared to other species in the family Alcidae, and is almost certainly insufficient to sustain a stable population. The primary causes of nest failure were depredation (47% of total nest fates), mostly by red foxes (Vulpes vulpes), and unexplained nestling mortality on the nest (21% of nest fates). Saxitoxin and/or pathogenic endoparasite burdens were observed in five of six necropsied chick carcasses, suggesting possible causes for chick mortality not directly attributable to predation. Habitat characteristics of Kittlitz's murrelet nest sites differed significantly from unused sites at several scales. At a small scale (within 5 m of the nest), nest sites had a lower percent coverage of vegetation and higher percent coverage of intermediate-sized rocks (5–30 cm diameter), compared to randomly selected unused sites. Nest sites were also located on steeper, more north-facing slopes compared to randomly selected sites. Nest sites also had a lower percent coverage of vegetation than randomly-selected sites at larger scales (within 25 m and 50 m of the nest site). Nest sites were located significantly farther from the edge of densely-vegetated habitats than random sites. There was no evidence that nest sites were different from randomly-selected sites in terms of elevation, proximity to ridgelines, or proximity to the open ocean, although a low degree of variation within the study area for these habitat characteristics may have precluded detection of potential differences. Nest survival rates did not co-vary with slope, percent vegetation coverage, distance from vegetated edges, or percent cover of intermediate-sized rocks; however, this result may be an artifact of a limited sample size. The results of this thesis will provide managers with a better understanding of the factors that may limit Kittlitz's murrelet nesting success, such as nest predation and forage fish availability, as well as factors that may influence the quality and distribution of Kittlitz’s murrelet nesting habitat in the future, given on-going and progressive climate change. Title: Breeding ecology and nest site selection of Kittlitz's murrelets on Kodiak Island, Alaska Author: Lawonn, Matthew James The Kittlitz's murrelet (Brachyramphus brevirostris) is a rare member of the seabird family Alcidae that breeds in coastal areas of Alaska and Beringian Russia. The species belongs to the genus Brachyramphus, an unusual seabird taxon in which all three extant species nest non-colonially, situating their nests up to 75 km inland from coastal marine waters. This nesting strategy is different from that of most seabird species, which tend to nest colonially on remote islands or sea cliffs, where terrestrial predators are generally absent or cannot easily access nests. Within the genus Brachyramphus, Kittlitz's murrelet is notable because a majority of the global population appears to nest on the surface of the ground in rocky alpine habitat near inland or tidewater glaciers, foraging in adjacent marine waters influenced by glacial outflows. The unusual nesting habits of Kittlitz's murrelet have made the study of its nesting ecology difficult, and gaps therefore exist in our understanding of the species' breeding biology. Kittlitz's murrelet populations have declined substantially in core areas of its range, causing the U. S. Fish and Wildlife Service to designate the species as a candidate for protection under the Endangered Species Act. A better understanding of Kittlitz's murrelet nesting ecology is crucial for determining potential causes of these declines and for future management of the species. To this end, I studied Kittlitz's murrelet breeding ecology and nest site selection during 2008-2011 on Kodiak Island, Alaska, in an unglaciated area that was recently found to have large numbers of accessible nests. I and my colleagues found 53 active Kittlitz's murrelet nests in inland scree-dominated habitats and placed remote, motion-sensing cameras at 33 nests. Adults exchanged incubation duties at the nest every 24 or 48 h, almost exclusively during early morning twilight. Following hatching of eggs, parents provisioned their single nestling with an average of 3.9 to 4.8 fish per day, depending on the year. Parental visits to the nest during chick-rearing occurred primarily after sunrise in the early to mid-morning hours, and during evening twilight. Fish were delivered singly to the chick, and Pacific sand lance (Ammodytes hexapterus), a high-lipid forage fish, accounted for about 92% of all identifiable chick meal deliveries. Chick growth rates were high relative to confamilial species, consistent with the high quality of chick diets; the logistic growth rate constant (K) was 0.291, greater than that for any other semi-precocial alcid. Chicks fledged an average of 24.8 d after hatching and asymptotic chick body mass averaged about 135.5 g, approximately 58% of adult body mass. Age at fledging, asymptotic chick body mass (% adult mass), and the number of meal deliveries required to fledge a chick were all lower than or as low as any other species of semi-precocial alcid. The average estimated nest survival rate during 2008-2011 was 0.093 (95% CI = 0.01–0.30), which is extremely low compared to other species in the family Alcidae, and is almost certainly insufficient to sustain a stable population. The primary causes of nest failure were depredation (47% of total nest fates), mostly by red foxes (Vulpes vulpes), and unexplained nestling mortality on the nest (21% of nest fates). Saxitoxin and/or pathogenic endoparasite burdens were observed in five of six necropsied chick carcasses, suggesting possible causes for chick mortality not directly attributable to predation. Habitat characteristics of Kittlitz's murrelet nest sites differed significantly from unused sites at several scales. At a small scale (within 5 m of the nest), nest sites had a lower percent coverage of vegetation and higher percent coverage of intermediate-sized rocks (5–30 cm diameter), compared to randomly selected unused sites. Nest sites were also located on steeper, more north-facing slopes compared to randomly selected sites. Nest sites also had a lower percent coverage of vegetation than randomly-selected sites at larger scales (within 25 m and 50 m of the nest site). Nest sites were located significantly farther from the edge of densely-vegetated habitats than random sites. There was no evidence that nest sites were different from randomly-selected sites in terms of elevation, proximity to ridgelines, or proximity to the open ocean, although a low degree of variation within the study area for these habitat characteristics may have precluded detection of potential differences. Nest survival rates did not co-vary with slope, percent vegetation coverage, distance from vegetated edges, or percent cover of intermediate-sized rocks; however, this result may be an artifact of a limited sample size. The results of this thesis will provide managers with a better understanding of the factors that may limit Kittlitz's murrelet nesting success, such as nest predation and forage fish availability, as well as factors that may influence the quality and distribution of Kittlitz’s murrelet nesting habitat in the future, given on-going and progressive climate change. Close

• 7297. [Article] Conserving energy by environmentally acceptable practices in maintaining and procuring transmission poles for long service ; October 1996

  The Cooperative continues to actively address a diverse array of issues related to the effective use of wood utility poles. The trials to evaluate the effectiveness of MITC-Fume are now in their seventh ...

  Citation × Citation Citation Abstract Copy Title: Conserving energy by environmentally acceptable practices in maintaining and procuring transmission poles for long service ; October 1996 Author: Morrell, Jeffrey J., Oregon State University. Dept. of Forest Products, Corden, M. E. (Malcolm E.) The Cooperative continues to actively address a diverse array of issues related to the effective use of wood utility poles. The trials to evaluate the effectiveness of MITC-Fume are now in their seventh year and continue to show that methylisothiocyanate (MITC) levels in MITC-Fume treatments remain higher than comparable metham sodium treatments. The levels of chemical are, however, declining, suggesting that this treatment may need replenishment in 3 to 5 years. Trials with the solid wood fumigant Basamid continue to show that MITC release can be enhanced by addition of small amounts of copper. Field trials suggest that these additives become less important with time. As a result, unamended Basamid may be suitable for treatment where the risk of immediate decay is not high, but the utility wishes to protect against future attack. Field trials with various water-diffusible internal treatments continue to show that these treatments move more slowly through Douglas-fir heartwood than do fumigants. Boron levels in pole sections treated with fused borate rods remain at levels that will protect against fungal attack 6 years after treatment. Similar trials with a boron/ fluoride rod indicate that neither fluoride or boron levels in the poles are adequate for wood protection 2 years after treatment. While the dosages tested were relatively low, the volumes of chemical were similar to the liquid volumes normally applied during internal remedial treatment. We will sample these poles next year to ensure that our measurements accurately reflect the chemical levels present. Trials to evaluate the effects of glycol on boron movement from fused borate rods suggest that glycol enhanced boron diffusion to only a slight extent. This effect was most pronounced at lower moisture contents. This trial was established to identify methods for improving boron movement in drier wood. In addition, moisture measurements in these poles suggest the internal wood moisture content varies widely both seasonally and positionally. While elevated moisture levels can negatively affect the movement of gaseous fumigants, excess moisture is critical for diffusion of boron or fluoride and its absence around the treatment site can markedly reduce the efficacy of rod treatments. These poles will continue to be monitored to assess both boron movement and seasonal changes in moisture content. Trials to identify safe, effective and easily used systems for protecting wood exposed during field fabrication are continuing. Boron and fluoride continue to provide excellent protection to field drilled bolt holes. These treatments are safe and easy to apply, and have provided protection in our field test for 14 years. Trials of similar formulations on simulated decking are also reported to provide additional information on the ability of boron and fluoride to protect exposed Douglas-fir heartwood. Efforts to improve the effectiveness of through boring as a method for enhancing the treatment of Douglas-fir poles are continuing. This past year, we evaluated preservative distribution around through bored holes as a means of developing optimum through boring patterns that maximized treatment while minimizing potential strength effects. These trials suggest the diamond shaped through boring zone of effect is relatively narrow. This information will be used in the coming year to construct optimum patterns for poles of various classes. The goal of this project is to develop a standard through boring pattern that would permit automation of the process. This would create the potential for cost savings on new poles. Trials to evaluate the durability of western redcedar are nearly complete. These trials were initiated because of concerns that second growth western redcedar might be less durable than poles cut from older trees. As expected, cedar varied widely in its resistance to fungal attack. This resistance, however, was not related to tree age, suggesting that there might not be a difference between so-called "old-growth" and "second growth" material. These data will be more thoroughly analyzed once the final set of trials are completed. In addition, we are evaluating more rapid methods for assessing cedar durability by measuring tropolone content. Tropolones are an important component of the extractives that make cedar heartwood so durable. Field trials of various externally applied supplemental groundline treatments are continuing at sites in Oregon, California, and New York. Trials in Corvallis, Oregon, have shown that various copper naphthenate, fluoride or boron based systems are at least as effective as the pentachlorophenol (penta) based systems that were formerly used for this purpose. Penta concentrations in one system have now declined below a protective level, while the copper based systems continue to remain at a protective level. Field trials in California are following similar trends and indicate that the alternative systems will provide comparable performance. Fungus cellar trials of copper naphthenate treated western redcedar stakes continue to show that this chemical provides excellent protection to cedar sapwood. Weathered wood that was treated with copper naphthenate continues to perform more poorly than freshly sawn wood treated to similar retention levels. Variations in permeability likely account for these differences. A new Wood Pole Maintenance Manual has been completed and is now ready for distribution. This update of the 1979 publication includes more information on initial pole procurement and closely follows the video by the same name that we produced in 1994. Title: Conserving energy by environmentally acceptable practices in maintaining and procuring transmission poles for long service ; October 1996 Author: Morrell, Jeffrey J., Oregon State University. Dept. of Forest Products, Corden, M. E. (Malcolm E.) The Cooperative continues to actively address a diverse array of issues related to the effective use of wood utility poles. The trials to evaluate the effectiveness of MITC-Fume are now in their seventh year and continue to show that methylisothiocyanate (MITC) levels in MITC-Fume treatments remain higher than comparable metham sodium treatments. The levels of chemical are, however, declining, suggesting that this treatment may need replenishment in 3 to 5 years. Trials with the solid wood fumigant Basamid continue to show that MITC release can be enhanced by addition of small amounts of copper. Field trials suggest that these additives become less important with time. As a result, unamended Basamid may be suitable for treatment where the risk of immediate decay is not high, but the utility wishes to protect against future attack. Field trials with various water-diffusible internal treatments continue to show that these treatments move more slowly through Douglas-fir heartwood than do fumigants. Boron levels in pole sections treated with fused borate rods remain at levels that will protect against fungal attack 6 years after treatment. Similar trials with a boron/ fluoride rod indicate that neither fluoride or boron levels in the poles are adequate for wood protection 2 years after treatment. While the dosages tested were relatively low, the volumes of chemical were similar to the liquid volumes normally applied during internal remedial treatment. We will sample these poles next year to ensure that our measurements accurately reflect the chemical levels present. Trials to evaluate the effects of glycol on boron movement from fused borate rods suggest that glycol enhanced boron diffusion to only a slight extent. This effect was most pronounced at lower moisture contents. This trial was established to identify methods for improving boron movement in drier wood. In addition, moisture measurements in these poles suggest the internal wood moisture content varies widely both seasonally and positionally. While elevated moisture levels can negatively affect the movement of gaseous fumigants, excess moisture is critical for diffusion of boron or fluoride and its absence around the treatment site can markedly reduce the efficacy of rod treatments. These poles will continue to be monitored to assess both boron movement and seasonal changes in moisture content. Trials to identify safe, effective and easily used systems for protecting wood exposed during field fabrication are continuing. Boron and fluoride continue to provide excellent protection to field drilled bolt holes. These treatments are safe and easy to apply, and have provided protection in our field test for 14 years. Trials of similar formulations on simulated decking are also reported to provide additional information on the ability of boron and fluoride to protect exposed Douglas-fir heartwood. Efforts to improve the effectiveness of through boring as a method for enhancing the treatment of Douglas-fir poles are continuing. This past year, we evaluated preservative distribution around through bored holes as a means of developing optimum through boring patterns that maximized treatment while minimizing potential strength effects. These trials suggest the diamond shaped through boring zone of effect is relatively narrow. This information will be used in the coming year to construct optimum patterns for poles of various classes. The goal of this project is to develop a standard through boring pattern that would permit automation of the process. This would create the potential for cost savings on new poles. Trials to evaluate the durability of western redcedar are nearly complete. These trials were initiated because of concerns that second growth western redcedar might be less durable than poles cut from older trees. As expected, cedar varied widely in its resistance to fungal attack. This resistance, however, was not related to tree age, suggesting that there might not be a difference between so-called "old-growth" and "second growth" material. These data will be more thoroughly analyzed once the final set of trials are completed. In addition, we are evaluating more rapid methods for assessing cedar durability by measuring tropolone content. Tropolones are an important component of the extractives that make cedar heartwood so durable. Field trials of various externally applied supplemental groundline treatments are continuing at sites in Oregon, California, and New York. Trials in Corvallis, Oregon, have shown that various copper naphthenate, fluoride or boron based systems are at least as effective as the pentachlorophenol (penta) based systems that were formerly used for this purpose. Penta concentrations in one system have now declined below a protective level, while the copper based systems continue to remain at a protective level. Field trials in California are following similar trends and indicate that the alternative systems will provide comparable performance. Fungus cellar trials of copper naphthenate treated western redcedar stakes continue to show that this chemical provides excellent protection to cedar sapwood. Weathered wood that was treated with copper naphthenate continues to perform more poorly than freshly sawn wood treated to similar retention levels. Variations in permeability likely account for these differences. A new Wood Pole Maintenance Manual has been completed and is now ready for distribution. This update of the 1979 publication includes more information on initial pole procurement and closely follows the video by the same name that we produced in 1994. Close

• 7298. [Article] Patterns of crown damage within a large wildfire in the Klamath-Siskiyou bioregion

  The 2002 Biscuit Fire burned through more than 200,000 ha of mixed conifer/ evergreen hardwood forests in southwestern Oregon and northwestern California. The remarkable size of the fire and the diversity ...

  Citation × Citation Citation Abstract Copy Title: Patterns of crown damage within a large wildfire in the Klamath-Siskiyou bioregion Author: Thompson, Jonathan R. The 2002 Biscuit Fire burned through more than 200,000 ha of mixed conifer/ evergreen hardwood forests in southwestern Oregon and northwestern California. The remarkable size of the fire and the diversity of conditions through which it burned provided an opportunity to analyze the correlates of burn severity across vegetation types and disturbance histories and to describe the weather, topographical, and fuel conditions that gave rise to the mosaic of crown damage. In chapter two, I focused on a region that had burned previously by the 1987 Silver Fire then was subject, in part, to salvage-logging and conifer planting before being reburned by the Biscuit Fire. I used the Landsat-based differenced normalized burn ratio (dNBR) to quantify severity in both fires and took a hypothesis-testing approach to answering two questions: First, was severity in the Biscuit Fire associated with severity in the Silver Fire in unmanaged areas? And second, did areas that were salvaged-logged and planted with conifers after the Silver Fire burn more or less severely in the Biscuit Fire than comparable unmanaged areas? I found that areas that burned severely in 1987 tended to re-burn at high severity in 2002, after controlling for the influence of several topographical and biophysical covariates. Areas unaffected by the initial fire tended to burn at the lowest severities in 2002. In addition, areas that were salvage-logged and planted after the initial fire burned more severely than comparable unmanaged areas, suggesting that post-fire logging and planting did not reduce future fire severity as had been suggested by some. In chapter three, I again focused on the twice-burned landscape, but this time I used a temporal sequence of digital aerial photography plots (6.25 ha) to measure changes in shrub-stratum, hardwood, and conifer cover. I estimated the strength and nature of relationships between crown damage and several fuel, topographical, weather, and management variables. Median crown damage, including damage to the shrub-stratum, on unmanaged plots was 63% after the Biscuit Fire and was most strongly related to damage in the Silver Fire. Plots that burned severely in the Silver Fire and had succeeded to a mix of shrubs and tree regeneration experienced high levels of Biscuit Fire damage. Plots dominated by large conifer cover after the Silver Fire had the lowest levels of Biscuit Fire canopy damage. Median crown damage was 39% for conifer cover and 85% for hardwood cover, and was most strongly related to daily average temperature and "burn period," an index of fire weather and fire suppression effort. Damage in the tree-stratum was largely independent of Silver Fire severity. Plots that had experienced stand replacing fire in 1987 and then were logged and planted with conifers had median crown damage of 100%. Plots that experienced a stand replacing fire but were unmanaged had median crown damage of 95%. The managed areas were at higher topographical positions and had greater total pre-fire cover, which may explain the small difference. These results suggest that in productive, fire-prone landscapes, the patch mosaic of young regenerating forest created by mixed-severity fire can structure the severity pattern of future wildfires occurring at short intervals and support the previous studies findings that post-fire logging and planting did not reduce fire severity. In Chapter four, I expanded my focus to include the entire region burned by the Biscuit Fire and again used digital aerial photos taken before and after the fire to interpret patterns of crown damage and relate them to several fuel, topographical, weather, and management variables. Ninety-eight percent of plots experienced some level of crown damage, but only 10% experienced complete crown damage. The median level of crown damage on unmanaged plots was 74%. Median conifer damage was 52%. The most important predictors of total crown damage were the percentage of pre-fire shrub-stratum vegetation cover and average daily temperature. The most important predictors of conifer damage were average daily temperature and burn period. Increasing levels of shrub-stratum cover were associated with increasing levels of conifer damage and hardwood damage. Large conifers had 32% median crown damage while small conifers had 62% median crown damage. Owing largely to widespread shrub-stratum cover, low-productivity ultramafic soils had 92% median crown damage compared to 59% on non-ultramafic sites. Patterns of damage were similar within the area that burned previously in the 1987 Silver Fire and edaphically comparable areas without a recently history of fire. Median crown damage in conifer plantations was 89% and plantation age was, by far, the most important predictor of the level of damage. Plantations under 20 years old experienced the highest rates of damage. I conclude that weather and vegetation conditions--not topography--were the primary determinants of Biscuit Fire crown damage. These findings suggest that in productive fire-prone ecosystems, fuel treatments that open tree canopies and stimulate shrub-stratum development may be counterproductive. Title: Patterns of crown damage within a large wildfire in the Klamath-Siskiyou bioregion Author: Thompson, Jonathan R. The 2002 Biscuit Fire burned through more than 200,000 ha of mixed conifer/ evergreen hardwood forests in southwestern Oregon and northwestern California. The remarkable size of the fire and the diversity of conditions through which it burned provided an opportunity to analyze the correlates of burn severity across vegetation types and disturbance histories and to describe the weather, topographical, and fuel conditions that gave rise to the mosaic of crown damage. In chapter two, I focused on a region that had burned previously by the 1987 Silver Fire then was subject, in part, to salvage-logging and conifer planting before being reburned by the Biscuit Fire. I used the Landsat-based differenced normalized burn ratio (dNBR) to quantify severity in both fires and took a hypothesis-testing approach to answering two questions: First, was severity in the Biscuit Fire associated with severity in the Silver Fire in unmanaged areas? And second, did areas that were salvaged-logged and planted with conifers after the Silver Fire burn more or less severely in the Biscuit Fire than comparable unmanaged areas? I found that areas that burned severely in 1987 tended to re-burn at high severity in 2002, after controlling for the influence of several topographical and biophysical covariates. Areas unaffected by the initial fire tended to burn at the lowest severities in 2002. In addition, areas that were salvage-logged and planted after the initial fire burned more severely than comparable unmanaged areas, suggesting that post-fire logging and planting did not reduce future fire severity as had been suggested by some. In chapter three, I again focused on the twice-burned landscape, but this time I used a temporal sequence of digital aerial photography plots (6.25 ha) to measure changes in shrub-stratum, hardwood, and conifer cover. I estimated the strength and nature of relationships between crown damage and several fuel, topographical, weather, and management variables. Median crown damage, including damage to the shrub-stratum, on unmanaged plots was 63% after the Biscuit Fire and was most strongly related to damage in the Silver Fire. Plots that burned severely in the Silver Fire and had succeeded to a mix of shrubs and tree regeneration experienced high levels of Biscuit Fire damage. Plots dominated by large conifer cover after the Silver Fire had the lowest levels of Biscuit Fire canopy damage. Median crown damage was 39% for conifer cover and 85% for hardwood cover, and was most strongly related to daily average temperature and "burn period," an index of fire weather and fire suppression effort. Damage in the tree-stratum was largely independent of Silver Fire severity. Plots that had experienced stand replacing fire in 1987 and then were logged and planted with conifers had median crown damage of 100%. Plots that experienced a stand replacing fire but were unmanaged had median crown damage of 95%. The managed areas were at higher topographical positions and had greater total pre-fire cover, which may explain the small difference. These results suggest that in productive, fire-prone landscapes, the patch mosaic of young regenerating forest created by mixed-severity fire can structure the severity pattern of future wildfires occurring at short intervals and support the previous studies findings that post-fire logging and planting did not reduce fire severity. In Chapter four, I expanded my focus to include the entire region burned by the Biscuit Fire and again used digital aerial photos taken before and after the fire to interpret patterns of crown damage and relate them to several fuel, topographical, weather, and management variables. Ninety-eight percent of plots experienced some level of crown damage, but only 10% experienced complete crown damage. The median level of crown damage on unmanaged plots was 74%. Median conifer damage was 52%. The most important predictors of total crown damage were the percentage of pre-fire shrub-stratum vegetation cover and average daily temperature. The most important predictors of conifer damage were average daily temperature and burn period. Increasing levels of shrub-stratum cover were associated with increasing levels of conifer damage and hardwood damage. Large conifers had 32% median crown damage while small conifers had 62% median crown damage. Owing largely to widespread shrub-stratum cover, low-productivity ultramafic soils had 92% median crown damage compared to 59% on non-ultramafic sites. Patterns of damage were similar within the area that burned previously in the 1987 Silver Fire and edaphically comparable areas without a recently history of fire. Median crown damage in conifer plantations was 89% and plantation age was, by far, the most important predictor of the level of damage. Plantations under 20 years old experienced the highest rates of damage. I conclude that weather and vegetation conditions--not topography--were the primary determinants of Biscuit Fire crown damage. These findings suggest that in productive fire-prone ecosystems, fuel treatments that open tree canopies and stimulate shrub-stratum development may be counterproductive. Close

• 7299. [Article] The oligocene and miocene geology of the Tillamook embayment Tillamook County, northwest Oregon

  Eleven sedimentary and volcanic rock units are mapped and described in the thesis area, and chronicle the dynamic geologic history of the Tillamook embayment from the Oligocene through the middle Mlocene. ...

  Citation × Citation Citation Abstract Copy Title: The oligocene and miocene geology of the Tillamook embayment Tillamook County, northwest Oregon Author: Parker, Michael J. (Michael John), 1958- Eleven sedimentary and volcanic rock units are mapped and described in the thesis area, and chronicle the dynamic geologic history of the Tillamook embayment from the Oligocene through the middle Mlocene. The oldest unit is the Zemorrian to early Saucesian Smuggler Cove formation, a bathyal tuffaceous mudstone with some thin- to thick-bedded tuff layers deposited on the middle to upper continental slope during a period of explosive silicic volcanism in the Western Cascade arc. Uppermost Smuggler Cove strata are coarser grained, grading upward to arkosic turbidite sandstone and mudstone and thick bloturbated silty sandstone deposited on the outer shelf during marine regression. This regression heralded the progradation of the overlying shallow-marine Bewley Creek formation (informal) depositional system. The Bewley Creek formation (informal) is proposed in this study for a sequence of pumiceous, volcaniclastic-rich lower Miocene feldspathic litharenites and lithic arkoses deposited during the Pillarlan-stage near the mouth of an ancestral Columbia River. The unit grades from bioturbated silty sandstone to fine-grained hummocky cross-stratified and coarser grained channelized sandstones deposited within, or peripheral to a wave-dominated delta or ebb tidal-delta channel complex. Progradatlon of the Bewley Creek formation may have been caused, in part, by increased volcaniclastic sedimentation attending a pulse of explosive volcanism in the adjacent Western Cascade arc. Reduced volcanic activity, possibly coupled with basin subsidence or eustatic sea level rise, resulted in deposition of mudstones of the Sutton Creek member (informal; proposed) of the Nye Mudstone. The Saucesian Sutton Creek member consists of bathyal, laminated, carbonaceous, and moderately tuffaceous mudstone deposited in an upper continental slope basin. The upper part of the unit contains common lithic to arkosic turbidite sandstone interbeds within nested channel-fill deposits. These strata represent a channelized shelf-slope break environment adjacent to the shallow-marine Angora Peak member of the Astoria Formation depositlonal system. Subsequent marine regression resulted in progradation of the Pillarian- to Newportian-stage arkosic-micaceous sandstone-rich Angora Peak member into the Tillamook embayment. Grainsize analysis, sandstone petrography, scanning electron microscopy, and heavy mineral analyses suggest these lower to middle Miocene mollusk-bearing, fine- to medium-grained sandstones were predominantly deposited near the mouth of an ancestral Columbia River. They accumulated on a high-energy Inner shelf within or down drift of a wave-dominated delta or ebb-tidal delta complex, evidenced by paleocurrent analyses, hummocky cross-stratification and trough cross-stratified submarine channel-fill sequences. The Angora Peak member disconformably overlies Zemorrian mudstones of the Smuggler Cove formation at Cape Kiwanda suggesting local uplift and erosion in that area, followed by Newportian stage transgression in the Tillamook embayment. Exotic cobbles and boulders of two mica granite and sedimentary quartzite at Cape Kiwanda were probably derived from the Idaho Batholith and Precambrian sandstone terrains in Montana, transported via an ancestral Columbia River and longshore current to the shelf possibly bound within tree root bundles. The Netarts Bay member (informal) of the Astoria Formation Is proposed In this study for a late Sauceslan package of fine-grained to pebbly amalgamated and interbedded turbidite, grainflow, and fluldized flow friable thick-bedded lithic arkoses. These massive sandstones contain large penecontemporaneously emplaced channel wall-blocks and naller slltstone rip-ups. These lower to middle Miocene strata were deposited in a submarine canyon head and channel complex offshore of the shallow-marine Angora Peak member depositlonal system. Netarts Bay strata cut Into the underlying Angora Peak shelf strata, and cut and Interfinger with bathyal slope mudstones of the Cannon Beach member of the Astoria Formation. The overlying lower Cannon Beach member Is composed of laminated bathyal mudstones with rare turbidite sandstone interbeds deposited in a coarse clastic-starved slope environment. Upper Cannon Beach member strata In the Tillamook area are characterized by micaceous arkosic and lithic arkosic turbidite sandstones that underlie and occur within nested channel-fill sequences. Bloturbated carbonaceous cross-bedded sandstone In the upper Cannon Beach member records shallowing of the Tillamook embayment to a channelized upper slope to shelf environment. The Tillamook embayment was uplifted and dissected prior to the arrival of six to ten Intracanyon subaerial and submarine lava flows of the Columbia River Basalt Group. These middle Miocene flows, delineatedon the basis of geochemical composition and magnetic polarity, Include (in stratigraphic order) the Grouse Creek (R2 low MgO-low T102), Winterwater (N2 low MgO-low Ti02), and Sentinel Bluffs (high MgO) units of the Grande Ronde Basalt, and the Ginkgo unit of the Frenchman Springs member of the Wanapum Basalt. Orientation of Grande Ponde Basalt foreset-bedded pillow palagonite complexes and lava delta sequences indicate that these Columbia River Basalt units flowed westward into the Tillainook embayment, possibly through a saddle in the ancestral Oregon Coast Range. Marine transgression and deposition of hummocky cross-stratified arkosic marine strata of the Sandstone of Whale Cove followed emplacement of the last Grande Ronde flows. This was succeeded by a regression, as Indicated by the overlying subaerial plagioclase-phyric Ginkgo Unit flow of the Frenchman Springs Basalt. Locally, Winterwater and Sentinel Bluffs unit basalt occur as brecciated peperitic sills and dikes. These were emplaced through the process of "auto-invasion" when dense lava injected downward Into semi-lithifled Tertiary strata under the influence of both a pressure head augmented by flashing steam, and steam blasting. The thesis area is crossed by a complex network of high-angle northwest- and northeast-tending normal and reverse faults, and both low and high-angle east-trending reverse and thrust faults. These faults may have developed through a north-south compressional tectonic regime, a dextral shear couple, or a combination of these two tectonic regimes. Many faults cut Columbia River Basalt units and are thus middle Miocene or younger in age. Tertiary strata including the Columbia River Basalts are also folded within a broad westward-plunging syncline which suggests a middle Miocene or younger compressional event. Source rock analyses indicate that the mudstones of the Cannon Beach member, Sutton Creek member, and Smuggler Cove formation contain type III kerogen capable of generating natural gas only. Although these rocks have thermally innature vitrinite reflectance values, they contain sufficiently high total organic carbon content to be considered potential lean source rocks. Arkosic sandstones of the Angora Peak and Netarts Bay members have fair to good reservoir rock characteristics, and may represent reservoirs offshore for matured hydrocarbons generated from deeply buried source rocks. Title: The oligocene and miocene geology of the Tillamook embayment Tillamook County, northwest Oregon Author: Parker, Michael J. (Michael John), 1958- Eleven sedimentary and volcanic rock units are mapped and described in the thesis area, and chronicle the dynamic geologic history of the Tillamook embayment from the Oligocene through the middle Mlocene. The oldest unit is the Zemorrian to early Saucesian Smuggler Cove formation, a bathyal tuffaceous mudstone with some thin- to thick-bedded tuff layers deposited on the middle to upper continental slope during a period of explosive silicic volcanism in the Western Cascade arc. Uppermost Smuggler Cove strata are coarser grained, grading upward to arkosic turbidite sandstone and mudstone and thick bloturbated silty sandstone deposited on the outer shelf during marine regression. This regression heralded the progradation of the overlying shallow-marine Bewley Creek formation (informal) depositional system. The Bewley Creek formation (informal) is proposed in this study for a sequence of pumiceous, volcaniclastic-rich lower Miocene feldspathic litharenites and lithic arkoses deposited during the Pillarlan-stage near the mouth of an ancestral Columbia River. The unit grades from bioturbated silty sandstone to fine-grained hummocky cross-stratified and coarser grained channelized sandstones deposited within, or peripheral to a wave-dominated delta or ebb tidal-delta channel complex. Progradatlon of the Bewley Creek formation may have been caused, in part, by increased volcaniclastic sedimentation attending a pulse of explosive volcanism in the adjacent Western Cascade arc. Reduced volcanic activity, possibly coupled with basin subsidence or eustatic sea level rise, resulted in deposition of mudstones of the Sutton Creek member (informal; proposed) of the Nye Mudstone. The Saucesian Sutton Creek member consists of bathyal, laminated, carbonaceous, and moderately tuffaceous mudstone deposited in an upper continental slope basin. The upper part of the unit contains common lithic to arkosic turbidite sandstone interbeds within nested channel-fill deposits. These strata represent a channelized shelf-slope break environment adjacent to the shallow-marine Angora Peak member of the Astoria Formation depositlonal system. Subsequent marine regression resulted in progradation of the Pillarian- to Newportian-stage arkosic-micaceous sandstone-rich Angora Peak member into the Tillamook embayment. Grainsize analysis, sandstone petrography, scanning electron microscopy, and heavy mineral analyses suggest these lower to middle Miocene mollusk-bearing, fine- to medium-grained sandstones were predominantly deposited near the mouth of an ancestral Columbia River. They accumulated on a high-energy Inner shelf within or down drift of a wave-dominated delta or ebb-tidal delta complex, evidenced by paleocurrent analyses, hummocky cross-stratification and trough cross-stratified submarine channel-fill sequences. The Angora Peak member disconformably overlies Zemorrian mudstones of the Smuggler Cove formation at Cape Kiwanda suggesting local uplift and erosion in that area, followed by Newportian stage transgression in the Tillamook embayment. Exotic cobbles and boulders of two mica granite and sedimentary quartzite at Cape Kiwanda were probably derived from the Idaho Batholith and Precambrian sandstone terrains in Montana, transported via an ancestral Columbia River and longshore current to the shelf possibly bound within tree root bundles. The Netarts Bay member (informal) of the Astoria Formation Is proposed In this study for a late Sauceslan package of fine-grained to pebbly amalgamated and interbedded turbidite, grainflow, and fluldized flow friable thick-bedded lithic arkoses. These massive sandstones contain large penecontemporaneously emplaced channel wall-blocks and naller slltstone rip-ups. These lower to middle Miocene strata were deposited in a submarine canyon head and channel complex offshore of the shallow-marine Angora Peak member depositlonal system. Netarts Bay strata cut Into the underlying Angora Peak shelf strata, and cut and Interfinger with bathyal slope mudstones of the Cannon Beach member of the Astoria Formation. The overlying lower Cannon Beach member Is composed of laminated bathyal mudstones with rare turbidite sandstone interbeds deposited in a coarse clastic-starved slope environment. Upper Cannon Beach member strata In the Tillamook area are characterized by micaceous arkosic and lithic arkosic turbidite sandstones that underlie and occur within nested channel-fill sequences. Bloturbated carbonaceous cross-bedded sandstone In the upper Cannon Beach member records shallowing of the Tillamook embayment to a channelized upper slope to shelf environment. The Tillamook embayment was uplifted and dissected prior to the arrival of six to ten Intracanyon subaerial and submarine lava flows of the Columbia River Basalt Group. These middle Miocene flows, delineatedon the basis of geochemical composition and magnetic polarity, Include (in stratigraphic order) the Grouse Creek (R2 low MgO-low T102), Winterwater (N2 low MgO-low Ti02), and Sentinel Bluffs (high MgO) units of the Grande Ronde Basalt, and the Ginkgo unit of the Frenchman Springs member of the Wanapum Basalt. Orientation of Grande Ponde Basalt foreset-bedded pillow palagonite complexes and lava delta sequences indicate that these Columbia River Basalt units flowed westward into the Tillainook embayment, possibly through a saddle in the ancestral Oregon Coast Range. Marine transgression and deposition of hummocky cross-stratified arkosic marine strata of the Sandstone of Whale Cove followed emplacement of the last Grande Ronde flows. This was succeeded by a regression, as Indicated by the overlying subaerial plagioclase-phyric Ginkgo Unit flow of the Frenchman Springs Basalt. Locally, Winterwater and Sentinel Bluffs unit basalt occur as brecciated peperitic sills and dikes. These were emplaced through the process of "auto-invasion" when dense lava injected downward Into semi-lithifled Tertiary strata under the influence of both a pressure head augmented by flashing steam, and steam blasting. The thesis area is crossed by a complex network of high-angle northwest- and northeast-tending normal and reverse faults, and both low and high-angle east-trending reverse and thrust faults. These faults may have developed through a north-south compressional tectonic regime, a dextral shear couple, or a combination of these two tectonic regimes. Many faults cut Columbia River Basalt units and are thus middle Miocene or younger in age. Tertiary strata including the Columbia River Basalts are also folded within a broad westward-plunging syncline which suggests a middle Miocene or younger compressional event. Source rock analyses indicate that the mudstones of the Cannon Beach member, Sutton Creek member, and Smuggler Cove formation contain type III kerogen capable of generating natural gas only. Although these rocks have thermally innature vitrinite reflectance values, they contain sufficiently high total organic carbon content to be considered potential lean source rocks. Arkosic sandstones of the Angora Peak and Netarts Bay members have fair to good reservoir rock characteristics, and may represent reservoirs offshore for matured hydrocarbons generated from deeply buried source rocks. Close

• 7300. [Article] Structure of the southern Mormon Mountains, Clark County, Nevada and regional structural synthesis : fold-thrust and basin-range structure in southern Nevada, southwest Utah, and northwest Arizona

  Detailed geologic mapping in the Mormon Mountains and new geophysical data provide significant insight into contractional and extensional tectonics in southern Nevada, southwest Utah, and northwest Arizona. ...

  Citation × Citation Citation Abstract Copy Title: Structure of the southern Mormon Mountains, Clark County, Nevada and regional structural synthesis : fold-thrust and basin-range structure in southern Nevada, southwest Utah, and northwest Arizona Author: Carpenter, James Anthony Detailed geologic mapping in the Mormon Mountains and new geophysical data provide significant insight into contractional and extensional tectonics in southern Nevada, southwest Utah, and northwest Arizona. The rocks in the region were complexly deformed during two distinct tectonic episodes. Numerous interrelated events occurred within each episode. The first tectonic episode, related to the Sevier orogeny, was characterized by east-west crustal shortening which culminated in thin-skinned decollement style folding and thrusting during the Cretaceous. The Virgin-Beaver Dam Mountains anticline, a Laramide-type basement-involved uplift, represents the only thick-skinned contractional structure in the region. The second tectonic episode, related to basin-range rifting, was characterized by east-west crustal extension which was accommodated by high-angle normal faults, with dips averaging 60 degrees, in the brittle upper crust. In this area, basin-range rifting initiated in the Oligocene and continued to Recent time. Relations in the North Muddy Mountains in southern Nevada suggest that the Muddy Mountain thrust sheet advanced and overrode the Weiser syncline during the Cenomanian and may have continued to advance in Turonian time. In the southern Mormon Mountains, the Cambrian Bonanza King Formation lies in the hanging wall flat position in thrust contact with the overturned Petrified Forest Member of the Triassic Chinle Formation at the footwall ramp. The thrust sheet advanced eastward more than 30 km from the place of origin. Thrust imbrication, and probably the formation of hanging wall horses, likely occurred as the Muddy Mountain thrust sheet encountered and ascended up the footwall ramp zone (composed largely of competent carbonate rocks) where slices of the thrust sheet (hanging wall horses) splayed of f and accreted to the footwall ramp zone. A detailed retrodeformable (balanced) regional structure section suggests that fold-thrust shortening at the latitude of the Mormon Mountains is a minimum of about 26%. Extension-related structures overprint older fold-thrust structures in the Mormon Mountains. The west-plunging east-trending Candy Peak syncline is one of a family of fold structures related to basin-range rifting. The syncline formed in pre-Miocene time in association with the northeast-striking Reber Mountain normal fault directly north and the northeast-striking Dry Canyon right-lateral strike-slip fault directly south. The Tortoise Flat synform, which lies southeast of the Dry Canyon fault, developed in Miocene and possibly Pliocene time by right-lateral flexure of early Miocene Horse Spring beds as a result of drag associated with the Dry Canyon fault. The Dry Canyon fault and the Tortoise Flat synform are interpreted to be part of the right-lateral Moapa Peak-Reber Mountain shear zone system in the southern Mormon Mountains. Therefore, the time of formation of the Moapa Peak-Reber Mountain shear zone system is pre-Miocene to possibly Pliocene. The shear zone system formed in response to different amounts of west-directed extension-related movement of the hanging wall block of the high-angle Virgin Beaver Dam Mountains fault, which initiated in the Oligocene. From this, the timing of the Moapa Peak-Reber Mountain shear zone, system is interpreted as Oligocene to Miocene, and possibly Pliocene. The interpretation of 261 km of seismic reflection sections suggests that large-displacement high-angle normal faults, typically with 60 degrees of dip, control horst and graben structure and accommodate extension by simple shear in the upper brittle crust. Such faults likely extend to depths of 15 to 18 km. Below this depth extension is thought to be accommodated by penetrative ductile deformation. A detailed retrodeformable (balanced) regional structure section suggests that basin-range extension at the latitude of the Mormon Mountains is about 17%. The Virgin-Beaver Dam Mountains high-angle normal fault is a large-displacement master fault in the area, having more than 8,000 in of normal vertical separation at the latitude of the Virgin Valley basin depocenter. Miocene doming and uplift of the Mormon Mountains occurred in response to displacement on the Virgin-Beaver Dam Mountains fault. The Virgin Valley basin formed as the hanging wall block downdropped, and the Mormon Mountains dome formed by relative uplift at the opposite end of the hanging wall block. Half-grabens, and tilted, folded, and faulted range blocks characterize basin-range crustal structure. Depositional growth relations are interpreted in basins from fanning-upward reflector geometry, and the wedge-shape of Oligocene to Recent syntectonic basin-fill sediments. Non-overlapping opposing east- and west-tilted half-grabens compose the Meadow Valley-California Wash basin. Seismic sections, gravity data, well data, and geologic mapping demonstrate that the Mormon Peak, Tule Springs Hills, and Beaver Dam/Castle Cliff "detachments," which were thought to be rooted low-angle normal faults, do not exist. The Mormon Peak and Beaver Dam/Castle Cliff low-angle normal faults are denudational fault planes below gravity slid masses. The widely distributed translocated Paleozoic blocks, which were thought to be remnant pieces of large hanging wall sheets ("extensional allochthons"), are disjunct rootless gravity slide blocks of minor tectonic significance. A large number of these rootless slide blocks lie on Pliocene and Quaternary basin-fill deposits. The Muddy Mountain-Tule Springs thrust, of Sevier age, was not reactivated as a crustal penetrating Tule Springs Hills low-angle normal fault, but is affected by small-scale gravity slide features. Rootless gravity slide blocks, secondary features to high-angle normal faults, commonly occur from instability as a result of the loss of lateral support induced by block faulting and the associated erosion of range blocks. Title: Structure of the southern Mormon Mountains, Clark County, Nevada and regional structural synthesis : fold-thrust and basin-range structure in southern Nevada, southwest Utah, and northwest Arizona Author: Carpenter, James Anthony Detailed geologic mapping in the Mormon Mountains and new geophysical data provide significant insight into contractional and extensional tectonics in southern Nevada, southwest Utah, and northwest Arizona. The rocks in the region were complexly deformed during two distinct tectonic episodes. Numerous interrelated events occurred within each episode. The first tectonic episode, related to the Sevier orogeny, was characterized by east-west crustal shortening which culminated in thin-skinned decollement style folding and thrusting during the Cretaceous. The Virgin-Beaver Dam Mountains anticline, a Laramide-type basement-involved uplift, represents the only thick-skinned contractional structure in the region. The second tectonic episode, related to basin-range rifting, was characterized by east-west crustal extension which was accommodated by high-angle normal faults, with dips averaging 60 degrees, in the brittle upper crust. In this area, basin-range rifting initiated in the Oligocene and continued to Recent time. Relations in the North Muddy Mountains in southern Nevada suggest that the Muddy Mountain thrust sheet advanced and overrode the Weiser syncline during the Cenomanian and may have continued to advance in Turonian time. In the southern Mormon Mountains, the Cambrian Bonanza King Formation lies in the hanging wall flat position in thrust contact with the overturned Petrified Forest Member of the Triassic Chinle Formation at the footwall ramp. The thrust sheet advanced eastward more than 30 km from the place of origin. Thrust imbrication, and probably the formation of hanging wall horses, likely occurred as the Muddy Mountain thrust sheet encountered and ascended up the footwall ramp zone (composed largely of competent carbonate rocks) where slices of the thrust sheet (hanging wall horses) splayed of f and accreted to the footwall ramp zone. A detailed retrodeformable (balanced) regional structure section suggests that fold-thrust shortening at the latitude of the Mormon Mountains is a minimum of about 26%. Extension-related structures overprint older fold-thrust structures in the Mormon Mountains. The west-plunging east-trending Candy Peak syncline is one of a family of fold structures related to basin-range rifting. The syncline formed in pre-Miocene time in association with the northeast-striking Reber Mountain normal fault directly north and the northeast-striking Dry Canyon right-lateral strike-slip fault directly south. The Tortoise Flat synform, which lies southeast of the Dry Canyon fault, developed in Miocene and possibly Pliocene time by right-lateral flexure of early Miocene Horse Spring beds as a result of drag associated with the Dry Canyon fault. The Dry Canyon fault and the Tortoise Flat synform are interpreted to be part of the right-lateral Moapa Peak-Reber Mountain shear zone system in the southern Mormon Mountains. Therefore, the time of formation of the Moapa Peak-Reber Mountain shear zone system is pre-Miocene to possibly Pliocene. The shear zone system formed in response to different amounts of west-directed extension-related movement of the hanging wall block of the high-angle Virgin Beaver Dam Mountains fault, which initiated in the Oligocene. From this, the timing of the Moapa Peak-Reber Mountain shear zone, system is interpreted as Oligocene to Miocene, and possibly Pliocene. The interpretation of 261 km of seismic reflection sections suggests that large-displacement high-angle normal faults, typically with 60 degrees of dip, control horst and graben structure and accommodate extension by simple shear in the upper brittle crust. Such faults likely extend to depths of 15 to 18 km. Below this depth extension is thought to be accommodated by penetrative ductile deformation. A detailed retrodeformable (balanced) regional structure section suggests that basin-range extension at the latitude of the Mormon Mountains is about 17%. The Virgin-Beaver Dam Mountains high-angle normal fault is a large-displacement master fault in the area, having more than 8,000 in of normal vertical separation at the latitude of the Virgin Valley basin depocenter. Miocene doming and uplift of the Mormon Mountains occurred in response to displacement on the Virgin-Beaver Dam Mountains fault. The Virgin Valley basin formed as the hanging wall block downdropped, and the Mormon Mountains dome formed by relative uplift at the opposite end of the hanging wall block. Half-grabens, and tilted, folded, and faulted range blocks characterize basin-range crustal structure. Depositional growth relations are interpreted in basins from fanning-upward reflector geometry, and the wedge-shape of Oligocene to Recent syntectonic basin-fill sediments. Non-overlapping opposing east- and west-tilted half-grabens compose the Meadow Valley-California Wash basin. Seismic sections, gravity data, well data, and geologic mapping demonstrate that the Mormon Peak, Tule Springs Hills, and Beaver Dam/Castle Cliff "detachments," which were thought to be rooted low-angle normal faults, do not exist. The Mormon Peak and Beaver Dam/Castle Cliff low-angle normal faults are denudational fault planes below gravity slid masses. The widely distributed translocated Paleozoic blocks, which were thought to be remnant pieces of large hanging wall sheets ("extensional allochthons"), are disjunct rootless gravity slide blocks of minor tectonic significance. A large number of these rootless slide blocks lie on Pliocene and Quaternary basin-fill deposits. The Muddy Mountain-Tule Springs thrust, of Sevier age, was not reactivated as a crustal penetrating Tule Springs Hills low-angle normal fault, but is affected by small-scale gravity slide features. Rootless gravity slide blocks, secondary features to high-angle normal faults, commonly occur from instability as a result of the loss of lateral support induced by block faulting and the associated erosion of range blocks. Close