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• 51. [Article] Evaluation of Large‑Scale Meteorological Patterns Associated with Temperature Extremes in the NARCCAP Regional Climate Model Simulations

  Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate ...

  Citation × Citation Citation Abstract Copy Title: Evaluation of Large‑Scale Meteorological Patterns Associated with Temperature Extremes in the NARCCAP Regional Climate Model Simulations Author: Loikith, Paul C., Waliser, Duane E., Lee, Huikyo, Neelin, J. David, Lintner, Benjamin, McGinnis, Seth, Mears, Linda, Kim, Jinwon Year: 2015 Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate Change Assessment Program. LSMPs are characterized through composites of surface air temperature, sea level pressure, and 500 hPa geopotential height anomalies concurrent with extreme temperature days. Six of the seventeen RCM simulations are driven by boundary conditions from reanalysis while the other eleven are driven by one of four global climate models (GCMs). Four illustrative case studies are analyzed in detail. Model fidelity in LSMP spatial representation is high for cold winter extremes near Chicago. Winter warm extremes are captured by most RCMs in northern California, with some notable exceptions. Model fidelity is lower for cool summer days near Houston and extreme summer heat events in the Ohio Valley. Physical interpretation of these patterns and identification of wellsimulated cases, such as for Chicago, boosts confidence in the ability of these models to simulate days in the tails of the temperature distribution. Results appear consistent with the expectation that the ability of an RCM to reproduce a realistically shaped frequency distribution for temperature, especially at the tails, is related to its fidelity in simulating LMSPs. Each ensemble member is ranked for its ability to reproduce LSMPs associated with observed warm and cold extremes, identifying systematically high performing RCMs and the GCMs that provide superior boundary forcing. The methodology developed here provides a framework for identifying regions where further process-based evaluation would improve the understanding of simulation error and help guide future model improvement and downscaling efforts. Title: Evaluation of Large‑Scale Meteorological Patterns Associated with Temperature Extremes in the NARCCAP Regional Climate Model Simulations Author: Loikith, Paul C., Waliser, Duane E., Lee, Huikyo, Neelin, J. David, Lintner, Benjamin, McGinnis, Seth, Mears, Linda, Kim, Jinwon Year: 2015 Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate Change Assessment Program. LSMPs are characterized through composites of surface air temperature, sea level pressure, and 500 hPa geopotential height anomalies concurrent with extreme temperature days. Six of the seventeen RCM simulations are driven by boundary conditions from reanalysis while the other eleven are driven by one of four global climate models (GCMs). Four illustrative case studies are analyzed in detail. Model fidelity in LSMP spatial representation is high for cold winter extremes near Chicago. Winter warm extremes are captured by most RCMs in northern California, with some notable exceptions. Model fidelity is lower for cool summer days near Houston and extreme summer heat events in the Ohio Valley. Physical interpretation of these patterns and identification of wellsimulated cases, such as for Chicago, boosts confidence in the ability of these models to simulate days in the tails of the temperature distribution. Results appear consistent with the expectation that the ability of an RCM to reproduce a realistically shaped frequency distribution for temperature, especially at the tails, is related to its fidelity in simulating LMSPs. Each ensemble member is ranked for its ability to reproduce LSMPs associated with observed warm and cold extremes, identifying systematically high performing RCMs and the GCMs that provide superior boundary forcing. The methodology developed here provides a framework for identifying regions where further process-based evaluation would improve the understanding of simulation error and help guide future model improvement and downscaling efforts. Close

• 52. [Article] A Metabolic Hypothesis for the Evolution of Temperature Effects on the Arterial PCO2 and pH of Vertebrate Ectotherms

  Body temperature increases in ectothermic vertebrates characteristically lead to both increases in arterial PCO2 (PaCO2) and declines in resting arterial pH (pHa) of about 0.017 pH units/°C increase in ...

  Citation × Citation Citation Abstract Copy Title: A Metabolic Hypothesis for the Evolution of Temperature Effects on the Arterial PCO2 and pH of Vertebrate Ectotherms Author: Hillman, Stanley S., Hedrick, Michael Scott Year: 2017 Body temperature increases in ectothermic vertebrates characteristically lead to both increases in arterial PCO2 (PaCO2) and declines in resting arterial pH (pHa) of about 0.017 pH units/°C increase in temperature. This ‘alphastat’ pH pattern has previously been interpreted as being evolutionarily-driven by the maintenance of a constant protonation state on the imidazole moiety of histidine protein residues, hence stabilizing protein structure-function. Analysis of the existing data for interclass responses of ectothermic vertebrates show different degrees of PaCO2 increases and pH declines with temperature between the classes with reptiles>amphibians>fish. The PaCO2 at the temperature where maximal aerobic metabolism (VO2max) is achieved is significantly and positively correlated with temperature for all vertebrate classes. For ectotherms, the PaCO2 where VO2max is greatest is also correlated with VO2max indicating there is an increased driving force for CO2 efflux that is lowest in fish, intermediate in amphibians and highest in reptiles. The pattern of increased PaCO2 and the resultant reduction of pHa to increased body temperature would serve to increase CO2 efflux, O2 delivery, blood buffering capacity and maintain ventilatory scope. This represents a new hypothesis for the selective advantage of arterial pH regulation from a systems physiology perspective in addition to the advantages of maintenance of protein structure-function. Title: A Metabolic Hypothesis for the Evolution of Temperature Effects on the Arterial PCO2 and pH of Vertebrate Ectotherms Author: Hillman, Stanley S., Hedrick, Michael Scott Year: 2017 Body temperature increases in ectothermic vertebrates characteristically lead to both increases in arterial PCO2 (PaCO2) and declines in resting arterial pH (pHa) of about 0.017 pH units/°C increase in temperature. This ‘alphastat’ pH pattern has previously been interpreted as being evolutionarily-driven by the maintenance of a constant protonation state on the imidazole moiety of histidine protein residues, hence stabilizing protein structure-function. Analysis of the existing data for interclass responses of ectothermic vertebrates show different degrees of PaCO2 increases and pH declines with temperature between the classes with reptiles>amphibians>fish. The PaCO2 at the temperature where maximal aerobic metabolism (VO2max) is achieved is significantly and positively correlated with temperature for all vertebrate classes. For ectotherms, the PaCO2 where VO2max is greatest is also correlated with VO2max indicating there is an increased driving force for CO2 efflux that is lowest in fish, intermediate in amphibians and highest in reptiles. The pattern of increased PaCO2 and the resultant reduction of pHa to increased body temperature would serve to increase CO2 efflux, O2 delivery, blood buffering capacity and maintain ventilatory scope. This represents a new hypothesis for the selective advantage of arterial pH regulation from a systems physiology perspective in addition to the advantages of maintenance of protein structure-function. Close

• 53. [Article] Estimation of Surface Water Temperature of the Tigris River System in Iraq

  Monitoring surface water temperatures (Tw) in lakes, rivers, and reservoirs is a key component of environmental management and influences water quality by affecting bio-geo chemical reaction rates, altering ...

  Citation × Citation Citation Abstract Copy Title: Estimation of Surface Water Temperature of the Tigris River System in Iraq Author: Al-Murib, M., Wells, Scott A., Talke, Stefan A. Year: 2017 Monitoring surface water temperatures (Tw) in lakes, rivers, and reservoirs is a key component of environmental management and influences water quality by affecting bio-geo chemical reaction rates, altering the saturation concentration of dissolved oxygen (DO), and influencing the susceptibility of fish to disease. Temperatures in the Tigris River, one of the largest rivers in the Middle East, are influenced by factors such as heat fluxes at the air-water and human activities such as direct discharge of water to the river. However, modeling and management of water temperature is limited by a paucity of in-situ data, which prevents calibration of models. In this study, we infill data gaps by estimating Tw using the thermal bands of both the Landsat 5 TM and Landsat 7 ETM+ sensors. These satellite-based estimates, typically measured once or twice a month with 60-120m resolution, are then used to develop a regression model that relates daily water temperature to daily air temperature and river flow. These estimates are used to define the Tw boundary conditions for a hydrodynamic and water quality model of the Tigris River based on a 2D implementation of the CE-QUAL-W2 (W2) numerical model. Initial results suggest that there is a significant agreement between modeled and remotely estimated data of Tw. Results suggest that short-wave solar radiation is the most important factor that controls seasonal Tw variations. However, anthropogenic influence is observed as a result of return irrigation flows and flows from Tharthar Lake. Title: Estimation of Surface Water Temperature of the Tigris River System in Iraq Author: Al-Murib, M., Wells, Scott A., Talke, Stefan A. Year: 2017 Monitoring surface water temperatures (Tw) in lakes, rivers, and reservoirs is a key component of environmental management and influences water quality by affecting bio-geo chemical reaction rates, altering the saturation concentration of dissolved oxygen (DO), and influencing the susceptibility of fish to disease. Temperatures in the Tigris River, one of the largest rivers in the Middle East, are influenced by factors such as heat fluxes at the air-water and human activities such as direct discharge of water to the river. However, modeling and management of water temperature is limited by a paucity of in-situ data, which prevents calibration of models. In this study, we infill data gaps by estimating Tw using the thermal bands of both the Landsat 5 TM and Landsat 7 ETM+ sensors. These satellite-based estimates, typically measured once or twice a month with 60-120m resolution, are then used to develop a regression model that relates daily water temperature to daily air temperature and river flow. These estimates are used to define the Tw boundary conditions for a hydrodynamic and water quality model of the Tigris River based on a 2D implementation of the CE-QUAL-W2 (W2) numerical model. Initial results suggest that there is a significant agreement between modeled and remotely estimated data of Tw. Results suggest that short-wave solar radiation is the most important factor that controls seasonal Tw variations. However, anthropogenic influence is observed as a result of return irrigation flows and flows from Tharthar Lake. Close

• 54. [Article] Can Significant Trends be Detected in Surface Air Temperature and Precipitation Over South America in Recent Decades?

  Trends in near-surface air temperature and precipitation over South America are examined for the periods 1975–2004 and 1955–2004, respectively, using multiple observational and climate model data sets. ...

  Citation × Citation Citation Abstract Copy Title: Can Significant Trends be Detected in Surface Air Temperature and Precipitation Over South America in Recent Decades? Author: de Barros Soares, Daniel, Lee, Huikyo, Loikith, Paul C., Barkhordarian, Armineh, Mechoso, Carlos R. Year: 2016 Trends in near-surface air temperature and precipitation over South America are examined for the periods 1975–2004 and 1955–2004, respectively, using multiple observational and climate model data sets. The results for observed near-surface air temperature show an overall warming trend over much of the continent, with the largest magnitudes over central Brazil. These observed trends are found to be statistically significant using pre-industrial control simulations from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) as the baseline to estimate natural climate variability. The observed trends are compared with those obtained in natural-only CMIP5 simulations, in which only natural forcings (i.e. volcanoes and solar variability) are included, and in historical CMIP5 simulations, in which anthropogenic forcings (i.e. changes in the atmospheric composition) are further incorporated. The historical CMIP5 simulations are more successful in capturing the observed temperature trends than the simulations with natural forcings only. It is suggested that anthropogenic warming is already evident over much of South America. Unlike the warming trends, observed precipitation trends over South America are less spatially coherent with both negative and positive values across the continent. Significant positive trends are found over South America in only one of the data sets used, and over a region that roughly encompasses the southern part of La Plata Basin (southern Brazil, Uruguay, and northeastern Argentina) in all data sets used. The historical CMIP5 simulations do not capture this feature. No firm conclusions are reached, therefore, for anthropogenic influences on precipitation changes in the period selected for study. Title: Can Significant Trends be Detected in Surface Air Temperature and Precipitation Over South America in Recent Decades? Author: de Barros Soares, Daniel, Lee, Huikyo, Loikith, Paul C., Barkhordarian, Armineh, Mechoso, Carlos R. Year: 2016 Trends in near-surface air temperature and precipitation over South America are examined for the periods 1975–2004 and 1955–2004, respectively, using multiple observational and climate model data sets. The results for observed near-surface air temperature show an overall warming trend over much of the continent, with the largest magnitudes over central Brazil. These observed trends are found to be statistically significant using pre-industrial control simulations from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) as the baseline to estimate natural climate variability. The observed trends are compared with those obtained in natural-only CMIP5 simulations, in which only natural forcings (i.e. volcanoes and solar variability) are included, and in historical CMIP5 simulations, in which anthropogenic forcings (i.e. changes in the atmospheric composition) are further incorporated. The historical CMIP5 simulations are more successful in capturing the observed temperature trends than the simulations with natural forcings only. It is suggested that anthropogenic warming is already evident over much of South America. Unlike the warming trends, observed precipitation trends over South America are less spatially coherent with both negative and positive values across the continent. Significant positive trends are found over South America in only one of the data sets used, and over a region that roughly encompasses the southern part of La Plata Basin (southern Brazil, Uruguay, and northeastern Argentina) in all data sets used. The historical CMIP5 simulations do not capture this feature. No firm conclusions are reached, therefore, for anthropogenic influences on precipitation changes in the period selected for study. Close

• 55. [Article] Towards Systematic Prediction of Urban Heat Islands: Grounding Measurements, Assessing Modeling Techniques

  While there exists extensive assessment of urban heat, we observe myriad methods for describing thermal distribution, factors that mediate temperatures, and potential impacts on urban populations. In addition, ...

  Citation × Citation Citation Abstract Copy Title: Towards Systematic Prediction of Urban Heat Islands: Grounding Measurements, Assessing Modeling Techniques Author: Voelkel, Jackson, Shandas, Vivek Year: 2017 While there exists extensive assessment of urban heat, we observe myriad methods for describing thermal distribution, factors that mediate temperatures, and potential impacts on urban populations. In addition, the limited spatial and temporal resolution of satellite-derived heat measurements may limit the capacity of decision makers to take effective actions for reducing mortalities in vulnerable populations whose locations require highly-refined measurements. Needed are high resolution spatial and temporal information for urban heat. In this study, we ask three questions: (1) how do urban heat islands vary throughout the day? (2) what statistical methods best explain the presence of temperatures at sub-meter spatial scales; and (3) what landscape features help to explain variation in urban heat islands? Using vehicle-based temperature measurements at three periods of the day in the Pacific Northwest city of Portland, Oregon (USA), we incorporate LiDAR-derived datasets, and evaluate three statistical techniques for modeling and predicting variation in temperatures during a heat wave. Our results indicate that the random forest technique best predicts temperatures, and that the evening model best explains the variation in temperature. The results suggest that ground-based measurements provide high levels of accuracy for describing the distribution of urban heat, its temporal variation, and specific locations where targeted interventions with communities can reduce mortalities from heat events. Title: Towards Systematic Prediction of Urban Heat Islands: Grounding Measurements, Assessing Modeling Techniques Author: Voelkel, Jackson, Shandas, Vivek Year: 2017 While there exists extensive assessment of urban heat, we observe myriad methods for describing thermal distribution, factors that mediate temperatures, and potential impacts on urban populations. In addition, the limited spatial and temporal resolution of satellite-derived heat measurements may limit the capacity of decision makers to take effective actions for reducing mortalities in vulnerable populations whose locations require highly-refined measurements. Needed are high resolution spatial and temporal information for urban heat. In this study, we ask three questions: (1) how do urban heat islands vary throughout the day? (2) what statistical methods best explain the presence of temperatures at sub-meter spatial scales; and (3) what landscape features help to explain variation in urban heat islands? Using vehicle-based temperature measurements at three periods of the day in the Pacific Northwest city of Portland, Oregon (USA), we incorporate LiDAR-derived datasets, and evaluate three statistical techniques for modeling and predicting variation in temperatures during a heat wave. Our results indicate that the random forest technique best predicts temperatures, and that the evening model best explains the variation in temperature. The results suggest that ground-based measurements provide high levels of accuracy for describing the distribution of urban heat, its temporal variation, and specific locations where targeted interventions with communities can reduce mortalities from heat events. Close

• 56. [Article] Electrical Detection of the Temperature Induced Melting Transition of a DNA Hairpin Covalently Attached to Gold Interdigitated Microelectrodes

  The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, ...

  Citation × Citation Citation Abstract Copy Title: Electrical Detection of the Temperature Induced Melting Transition of a DNA Hairpin Covalently Attached to Gold Interdigitated Microelectrodes Author: Brewood, Greg P., Rangineni, Yaswanth, Fish, Daniel J., Bhandiwad, Ashwini, Evans, David R., Solanki, Raj, Benight, Albert S. Year: 2008 The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, manner. The structural state of the hairpin was assessed by measuring four different electronic properties of the GIME (capacitance, impedance, dissipation factor and phase angle) as a function of temperature from 25 degrees C to 80 degrees C. Consistent changes in all four electronic properties of the GIME were observed over this temperature range, and attributed to the transition of the attached single-stranded DNA (ssDNA) from an intramolecular, folded hairpin structure to a melted ssDNA. The melting curve of the self-complementary single strand was also measured in solution using differential scanning calorimetry (DSC) and UV absorbance spectroscopy. Temperature dependent electronic measurements on the surface and absorbance versus temperature values measured in solution experiments were analyzed assuming a two-state process. The model analysis provided estimates of the thermodynamic transition parameters of the hairpin on the surface. Two-state analyses of optical melting data and DSC measurements provided evaluations of the thermodynamic transition parameters of the hairpin in solution. Comparison of surface and solution measurements provided quantitative evaluation of the effect of the surface on the thermodynamics of the melting transition of the DNA hairpin. Title: Electrical Detection of the Temperature Induced Melting Transition of a DNA Hairpin Covalently Attached to Gold Interdigitated Microelectrodes Author: Brewood, Greg P., Rangineni, Yaswanth, Fish, Daniel J., Bhandiwad, Ashwini, Evans, David R., Solanki, Raj, Benight, Albert S. Year: 2008 The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, manner. The structural state of the hairpin was assessed by measuring four different electronic properties of the GIME (capacitance, impedance, dissipation factor and phase angle) as a function of temperature from 25 degrees C to 80 degrees C. Consistent changes in all four electronic properties of the GIME were observed over this temperature range, and attributed to the transition of the attached single-stranded DNA (ssDNA) from an intramolecular, folded hairpin structure to a melted ssDNA. The melting curve of the self-complementary single strand was also measured in solution using differential scanning calorimetry (DSC) and UV absorbance spectroscopy. Temperature dependent electronic measurements on the surface and absorbance versus temperature values measured in solution experiments were analyzed assuming a two-state process. The model analysis provided estimates of the thermodynamic transition parameters of the hairpin on the surface. Two-state analyses of optical melting data and DSC measurements provided evaluations of the thermodynamic transition parameters of the hairpin in solution. Comparison of surface and solution measurements provided quantitative evaluation of the effect of the surface on the thermodynamics of the melting transition of the DNA hairpin. Close

• 57. [Article] The Effects of Anthropogenic Stressors on Mercury Concentrations and Community Composition of Freshwater Zooplankton

  Methylmercury (MeHg) bioaccumulation in freshwater aquatic systems is impacted by anthropogenic stressors, including climate change and excess nutrients. The goal of this study was to determine how warmer ...

  Citation × Citation Citation Abstract Copy Title: The Effects of Anthropogenic Stressors on Mercury Concentrations and Community Composition of Freshwater Zooplankton Author: Jordan, Meredith Powers Year: 2016 Methylmercury (MeHg) bioaccumulation in freshwater aquatic systems is impacted by anthropogenic stressors, including climate change and excess nutrients. The goal of this study was to determine how warmer water temperatures and excess nutrients would impact zooplankton communities and phytoplankton concentrations, and in turn increase or decrease MeHg concentrations in freshwater zooplankton. I used a 2x2 factorial design to determine if the interaction of temperature and nutrients would impact plankton metrics and zooplankton MeHg concentrations. Mesocosms were filled with Hg-contaminated water and plankton from Cottage Grove Reservoir, Oregon, U.S.A, a waterbody that has experienced decades of elevated MeHg concentrations and corresponding fish consumption advisories due to run-off from Black Butte Mine tailings, located within the watershed. Treatment combinations of warmer temperature (increased by 0.5°C) and nutrient addition (a single pulse of excess nitrogen and phosphorous), control, and a combination of temperature and nutrients were applied to mesocosms. While plankton did respond to treatments, zooplankton biomass and phytoplankton concentrations did not have significant relationships to MeHg concentrations. However, a significant interactive effect of nutrients and temperature was present: nutrients appeared to buffer against increased MeHg concentrations when temperature was elevated. The mechanisms for this interaction appear to be related to a shift to larger body size and an increase in abundance of Daphnia over copepods. Findings suggest that community composition and species-specific differences in both zooplankton and phytoplankton could play a role in MeHg transfer to higher trophic levels. Title: The Effects of Anthropogenic Stressors on Mercury Concentrations and Community Composition of Freshwater Zooplankton Author: Jordan, Meredith Powers Year: 2016 Methylmercury (MeHg) bioaccumulation in freshwater aquatic systems is impacted by anthropogenic stressors, including climate change and excess nutrients. The goal of this study was to determine how warmer water temperatures and excess nutrients would impact zooplankton communities and phytoplankton concentrations, and in turn increase or decrease MeHg concentrations in freshwater zooplankton. I used a 2x2 factorial design to determine if the interaction of temperature and nutrients would impact plankton metrics and zooplankton MeHg concentrations. Mesocosms were filled with Hg-contaminated water and plankton from Cottage Grove Reservoir, Oregon, U.S.A, a waterbody that has experienced decades of elevated MeHg concentrations and corresponding fish consumption advisories due to run-off from Black Butte Mine tailings, located within the watershed. Treatment combinations of warmer temperature (increased by 0.5°C) and nutrient addition (a single pulse of excess nitrogen and phosphorous), control, and a combination of temperature and nutrients were applied to mesocosms. While plankton did respond to treatments, zooplankton biomass and phytoplankton concentrations did not have significant relationships to MeHg concentrations. However, a significant interactive effect of nutrients and temperature was present: nutrients appeared to buffer against increased MeHg concentrations when temperature was elevated. The mechanisms for this interaction appear to be related to a shift to larger body size and an increase in abundance of Daphnia over copepods. Findings suggest that community composition and species-specific differences in both zooplankton and phytoplankton could play a role in MeHg transfer to higher trophic levels. Close

• 58. [Article] The Effects of Hypoxia and Temperature on Developing Embryos of the Annual Killifish Austrofundulus limnaeus

  Little is known about the physiology or biochemistry of hypoxia (reduced levels of oxygen) tolerance during development in vertebrate embryos. In most species, relatively brief bouts of severe hypoxia ...

  Citation × Citation Citation Abstract Copy Title: The Effects of Hypoxia and Temperature on Developing Embryos of the Annual Killifish Austrofundulus limnaeus Author: Anderson, Skye N. Year: 2012 Little is known about the physiology or biochemistry of hypoxia (reduced levels of oxygen) tolerance during development in vertebrate embryos. In most species, relatively brief bouts of severe hypoxia are lethal or teratogenic. An exception to such hypoxia intolerance is the annual killifish Austrofundulus limnaeus, in which populations persist in hypoxic environments. This species inhabits seasonal ponds in Venezuela, surviving through the dry season in the form of diapausing embryos. Embedded in the pond sediment, embryos of A. limnaeus are routinely exposed to hypoxia and anoxia (lack of oxygen) as part of their normal development. Here, we exposed embryos to various levels of PO2 (21.2, 15.6, 10.8, 8.4, 6.1, 3.6, and 2.2 kPa) at two different temperatures (25°C and 30°C) to study the effects on developmental rate and heart rate. We also measured enzyme activity and quantified DNA content of individual embryos to compare differences among the varying levels of hypoxia and temperature. Hypoxia caused a significant decline in developmental rate and caused a stage-specific decline in heart rate. Higher temperature caused an increase in the developmental rate for those embryos incubated at PO2 of 6.1 kPa and greater. Temperature had a negative effect by hindering development below a PO2 of 6.1 kPa. Total embryonic DNA content was reduced at low partial pressures (15.6, 10.8, 8.4, 6.1, 3.6, and 2.2 kPa) of oxygen. Citrate synthase, lactate dehydrogenase, and phosphoenolpyruvate carboxykinase were all down-regulated indicating a complete lack of enzymatic metabolic compensation to combat reduced oxygen levels. Title: The Effects of Hypoxia and Temperature on Developing Embryos of the Annual Killifish Austrofundulus limnaeus Author: Anderson, Skye N. Year: 2012 Little is known about the physiology or biochemistry of hypoxia (reduced levels of oxygen) tolerance during development in vertebrate embryos. In most species, relatively brief bouts of severe hypoxia are lethal or teratogenic. An exception to such hypoxia intolerance is the annual killifish Austrofundulus limnaeus, in which populations persist in hypoxic environments. This species inhabits seasonal ponds in Venezuela, surviving through the dry season in the form of diapausing embryos. Embedded in the pond sediment, embryos of A. limnaeus are routinely exposed to hypoxia and anoxia (lack of oxygen) as part of their normal development. Here, we exposed embryos to various levels of PO2 (21.2, 15.6, 10.8, 8.4, 6.1, 3.6, and 2.2 kPa) at two different temperatures (25°C and 30°C) to study the effects on developmental rate and heart rate. We also measured enzyme activity and quantified DNA content of individual embryos to compare differences among the varying levels of hypoxia and temperature. Hypoxia caused a significant decline in developmental rate and caused a stage-specific decline in heart rate. Higher temperature caused an increase in the developmental rate for those embryos incubated at PO2 of 6.1 kPa and greater. Temperature had a negative effect by hindering development below a PO2 of 6.1 kPa. Total embryonic DNA content was reduced at low partial pressures (15.6, 10.8, 8.4, 6.1, 3.6, and 2.2 kPa) of oxygen. Citrate synthase, lactate dehydrogenase, and phosphoenolpyruvate carboxykinase were all down-regulated indicating a complete lack of enzymatic metabolic compensation to combat reduced oxygen levels. Close

• 59. [Article] The effects of temperature on the dispersion and reaggregation stages of development in the annual killifish, Austrofundulus limnaeus

  The dispersion and reaggreation [sic] stages have been described as a unique feature of embryonic development in annual killifish such as Austrofundulus limnaeus, a killifish that inhabits ephemeral ponds ...

  Citation × Citation Citation Abstract Copy Title: The effects of temperature on the dispersion and reaggregation stages of development in the annual killifish, Austrofundulus limnaeus Author: Cleaver, Timothy Grant Year: 2012 The dispersion and reaggreation [sic] stages have been described as a unique feature of embryonic development in annual killifish such as Austrofundulus limnaeus, a killifish that inhabits ephemeral ponds in the Maracaibo basin of Venezuela. These stages have previously been described as an atypical developmental progression in which blastomeres completely disperse on the surface of the yolk and then reaggregate into a mass of cells to form the embryo. Temperature affects the onset as well as the duration of this stage in related annual fishes. We have undertaken this study to show in detail the behavior of blastomere cells and their distributions as a function of developmental temperature. Embryos incubated at either 25 or 30°C were fixed and stained with Hoescht dye to allow visualization and quantification of cell number during the dispersion and reaggregation phases of development. The location of every cell nucleus on the embryo was assessed through photomicroscopy using inverted epifluorescent microsopy [sic]. This analysis revealed that the rate of cell division during the process of dispersion/reaggergation [sic] has a typical sensitivity to temperature with Q10 values of about 2-3. There is no indication that the pattern of blastomere movement and distribution is different in embryos incubated at 25°C versus 30°C. The primary developmental difference was observed as a temporary plateau in blastomere counts at 25°C followed by great variation of blastomere numbers in subsequent timepoints compared to the degree of variation observed in embryos incubated at 30°C. This trend fits the model that embryos developing at 25°C enter into a brief diapause-like event at the dispersion stage from which they emerge at a variable rate. Of great interest, at both temperatures examined, the majority of the dispersed blastomeres do not reaggregate and contribute to the formation of the primary embryonic axis. Prior studies have overemphasized blastomere reaggregation in A. limnaeus due to the limitations of the sampling methods used as well as overdependence upon a statistical test, the coefficient of dispersion. Thus, the present study sheds light on these early mischaracterizations of A. limnaeus development. Title: The effects of temperature on the dispersion and reaggregation stages of development in the annual killifish, Austrofundulus limnaeus Author: Cleaver, Timothy Grant Year: 2012 The dispersion and reaggreation [sic] stages have been described as a unique feature of embryonic development in annual killifish such as Austrofundulus limnaeus, a killifish that inhabits ephemeral ponds in the Maracaibo basin of Venezuela. These stages have previously been described as an atypical developmental progression in which blastomeres completely disperse on the surface of the yolk and then reaggregate into a mass of cells to form the embryo. Temperature affects the onset as well as the duration of this stage in related annual fishes. We have undertaken this study to show in detail the behavior of blastomere cells and their distributions as a function of developmental temperature. Embryos incubated at either 25 or 30°C were fixed and stained with Hoescht dye to allow visualization and quantification of cell number during the dispersion and reaggregation phases of development. The location of every cell nucleus on the embryo was assessed through photomicroscopy using inverted epifluorescent microsopy [sic]. This analysis revealed that the rate of cell division during the process of dispersion/reaggergation [sic] has a typical sensitivity to temperature with Q10 values of about 2-3. There is no indication that the pattern of blastomere movement and distribution is different in embryos incubated at 25°C versus 30°C. The primary developmental difference was observed as a temporary plateau in blastomere counts at 25°C followed by great variation of blastomere numbers in subsequent timepoints compared to the degree of variation observed in embryos incubated at 30°C. This trend fits the model that embryos developing at 25°C enter into a brief diapause-like event at the dispersion stage from which they emerge at a variable rate. Of great interest, at both temperatures examined, the majority of the dispersed blastomeres do not reaggregate and contribute to the formation of the primary embryonic axis. Prior studies have overemphasized blastomere reaggregation in A. limnaeus due to the limitations of the sampling methods used as well as overdependence upon a statistical test, the coefficient of dispersion. Thus, the present study sheds light on these early mischaracterizations of A. limnaeus development. Close

• 60. [Article] Climate Change Assessment in Columbia River Basin (CRB) Using Copula Based on Coupling of Temperature and Precipitation

  The multi downscaled-scenario products allow us to better assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Joint Probability distribution functions ...

  Citation × Citation Citation Abstract Copy Title: Climate Change Assessment in Columbia River Basin (CRB) Using Copula Based on Coupling of Temperature and Precipitation Author: Qin, Yueyue Year: 2015 The multi downscaled-scenario products allow us to better assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Joint Probability distribution functions (PDFs), of both the climatic variables, might help better understand the interdependence of the two, and thus in-turn help in accessing the future with confidence. In the present study, we have used multi-modelled statistically downscaled ensemble of precipitation and temperature variables. The dataset used is multi-model ensemble of 10 Global Climate Models (GCMs) downscaled product from CMIP5 daily dataset, using the Bias Correction and Spatial Downscaling (BCSD) technique, generated at Portland State University. The multi-model ensemble PDFs of both precipitation and temperature is evaluated for summer (dry) and winter (wet) periods for 10 sub-basins across Columbia River Basin (CRB). Eventually, Copula is applied to establish the joint distribution of two variables on multi-model ensemble data. Results have indicated that the probabilistic distribution helps remove the limitations on marginal distributions of variables in question and helps in better prediction. The joint distribution is then used to estimate the change in trends of said variables in future, along with estimation of the probabilities of the given change. The joint distribution trends are varied, but certainly positive, for summer and winter time scales based on sub-basins. Dry season, generally, is indicating towards higher positive changes in precipitation than temperature (as compared to historical) across sub-basins with wet season inferring otherwise. Probabilities of changes in future, as estimated by the joint precipitation and temperature, also indicates varied degree and forms during dry season whereas the wet season is rather constant across all the sub-basins. Title: Climate Change Assessment in Columbia River Basin (CRB) Using Copula Based on Coupling of Temperature and Precipitation Author: Qin, Yueyue Year: 2015 The multi downscaled-scenario products allow us to better assess the uncertainty of the variations of precipitation and temperature in the current and future periods. Joint Probability distribution functions (PDFs), of both the climatic variables, might help better understand the interdependence of the two, and thus in-turn help in accessing the future with confidence. In the present study, we have used multi-modelled statistically downscaled ensemble of precipitation and temperature variables. The dataset used is multi-model ensemble of 10 Global Climate Models (GCMs) downscaled product from CMIP5 daily dataset, using the Bias Correction and Spatial Downscaling (BCSD) technique, generated at Portland State University. The multi-model ensemble PDFs of both precipitation and temperature is evaluated for summer (dry) and winter (wet) periods for 10 sub-basins across Columbia River Basin (CRB). Eventually, Copula is applied to establish the joint distribution of two variables on multi-model ensemble data. Results have indicated that the probabilistic distribution helps remove the limitations on marginal distributions of variables in question and helps in better prediction. The joint distribution is then used to estimate the change in trends of said variables in future, along with estimation of the probabilities of the given change. The joint distribution trends are varied, but certainly positive, for summer and winter time scales based on sub-basins. Dry season, generally, is indicating towards higher positive changes in precipitation than temperature (as compared to historical) across sub-basins with wet season inferring otherwise. Probabilities of changes in future, as estimated by the joint precipitation and temperature, also indicates varied degree and forms during dry season whereas the wet season is rather constant across all the sub-basins. Close