Structural damage detection for in-service highway bridge under operational and environmental variability

NASA Astrophysics Data System (ADS)

Jin, Chenhao; Li, Jingcheng; Jang, Shinae; Sun, Xiaorong; Christenson, Richard

2015-03-01

Structural health monitoring has drawn significant attention in the past decades with numerous methodologies and applications for civil structural systems. Although many researchers have developed analytical and experimental damage detection algorithms through vibration-based methods, these methods are not widely accepted for practical structural systems because of their sensitivity to uncertain environmental and operational conditions. The primary environmental factor that influences the structural modal properties is temperature. The goal of this article is to analyze the natural frequency-temperature relationships and detect structural damage in the presence of operational and environmental variations using modal-based method. For this purpose, correlations between natural frequency and temperature are analyzed to select proper independent variables and inputs for the multiple linear regression model and neural network model. In order to capture the changes of natural frequency, confidence intervals to detect the damages for both models are generated. A long-term structural health monitoring system was installed on an in-service highway bridge located in Meriden, Connecticut to obtain vibration and environmental data. Experimental testing results show that the variability of measured natural frequencies due to temperature is captured, and the temperature-induced changes in natural frequencies have been considered prior to the establishment of the threshold in the damage warning system. This novel approach is applicable for structural health monitoring system and helpful to assess the performance of the structure for bridge management and maintenance.

A review of precipitation and temperature control on seedling emergence and establishment for ponderosa and lodgepole pine forest regeneration

USGS Publications Warehouse

Petrie, Matthew; Wildeman, A.M.; Bradford, John B.; Hubbard, R.M.; Lauenroth, W.K.

2016-01-01

The persistence of ponderosa pine and lodgepole pine forests in the 21st century depends to a large extent on how seedling emergence and establishment are influenced by driving climate and environmental variables, which largely govern forest regeneration. We surveyed the literature, and identified 96 publications that reported data on dependent variables of seedling emergence and/or establishment and one or more independent variables of air temperature, soil temperature, precipitation and moisture availability. Our review suggests that seedling emergence and establishment for both species is highest at intermediate temperatures (20 to 25 °C), and higher precipitation and higher moisture availability support a higher percentage of seedling emergence and establishment at daily, monthly and annual timescales. We found that ponderosa pine seedlings may be more sensitive to temperature fluctuations whereas lodgepole pine seedlings may be more sensitive to moisture fluctuations. In a changing climate, increasing temperatures and declining moisture availability may hinder forest persistence by limiting seedling processes. Yet, only 23 studies in our review investigated the effects of driving climate and environmental variables directly. Furthermore, 74 studies occurred in a laboratory or greenhouse, which do not often replicate the conditions experienced by tree seedlings in a field setting. It is therefore difficult to provide strong conclusions on how sensitive emergence and establishment in ponderosa and lodgepole pine are to these specific driving variables, or to investigate their potential aggregate effects. Thus, the effects of many driving variables on seedling processes remain largely inconclusive. Our review stresses the need for additional field and laboratory studies to better elucidate the effects of driving climate and environmental variables on seedling emergence and establishment for ponderosa and lodgepole pine.

Variation in the thermal parameters of Odontophrynus occidentalis in the Monte desert, Argentina: response to the environmental constraints.

PubMed

Sanabria, Eduardo Alfredo; Quiroga, Lorena Beatriz; Martino, Adolfo Ludovico

2012-03-01

We studied the variation of thermal parameters of Odontophrynus occidentalis between season (wet and dry) in the Monte desert (Argentina). We measured body temperatures, microhabitat temperatures, and operative temperatures; while in the laboratory, we measured the selected body temperatures. Our results show a change in the thermal parameters of O. occidentalis that is related to environmental constraints of their thermal niche. Environmental thermal constraints are present in both seasons (dry and wet), showing variations in thermal parameters studied. Apparently imposed environmental restrictions, the toads in nature always show body temperatures below the set point. Acclimatization is an advantage for toads because it allows them to bring more frequent body temperatures to the set point. The selected body temperature has seasonal intraindividual variability. These variations can be due to thermo-sensitivity of toads and life histories of individuals that limits their allocation and acquisition of resources. Possibly the range of variation found in selected body temperature is a consequence of the thermal environmental variation along the year. These variations of thermal parameters are commonly found in deserts and thermal bodies of nocturnal ectotherms. The plasticity of selected body temperature allows O. occidentales to have longer periods of activity for foraging and reproduction, while maintaining reasonable high performance at different temperatures. The plasticity in seasonal variation of the thermal parameters has been poorly studied, and is greatly advantageous to desert species during changes in both seasonal and daily temperature, as these environments are known for their high environmental variability. © 2012 WILEY PERIODICALS, INC.

The Relative Importance of Spatial and Local Environmental Factors in Determining Beetle Assemblages in the Inner Mongolia Grassland.

PubMed

Yu, Xiao-Dong; Lü, Liang; Wang, Feng-Yan; Luo, Tian-Hong; Zou, Si-Si; Wang, Cheng-Bin; Song, Ting-Ting; Zhou, Hong-Zhang

2016-01-01

The aim of this paper is to increase understanding of the relative importance of the input of geographic and local environmental factors on richness and composition of epigaeic steppe beetles (Coleoptera: Carabidae and Tenebrionidae) along a geographic (longitudinal/precipitation) gradient in the Inner Mongolia grassland. Specifically, we evaluate the associations of environmental variables representing climate and environmental heterogeneity with beetle assemblages. Beetles were sampled using pitfall traps at 25 sites scattered across the full geographic extent of the study biome in 2011-2012. We used variance partitioning techniques and multi-model selection based on the Akaike information criterion to assess the relative importance of the spatial and environmental variables on beetle assemblages. Species richness and abundance showed unimodal patterns along the geographic gradient. Together with space, climate variables associated with precipitation, water-energy balance and harshness of climate had strong explanatory power in richness pattern. Abundance pattern showed strongest association with variation in temperature and environmental heterogeneity. Climatic factors associated with temperature and precipitation variables and the interaction between climate with space were able to explain a substantial amount of variation in community structure. In addition, the turnover of species increased significantly as geographic distances increased. We confirmed that spatial and local environmental factors worked together to shape epigaeic beetle communities along the geographic gradient in the Inner Mongolia grassland. Moreover, the climate features, especially precipitation, water-energy balance and temperature, and the interaction between climate with space and environmental heterogeneity appeared to play important roles on controlling richness and abundance, and species compositions of epigaeic beetles.

Cold-Blooded Attention: Finger Temperature Predicts Attentional Performance.

PubMed

Vergara, Rodrigo C; Moënne-Loccoz, Cristóbal; Maldonado, Pedro E

2017-01-01

Thermal stress has been shown to increase the chances of unsafe behavior during industrial and driving performances due to reductions in mental and attentional resources. Nonetheless, establishing appropriate safety standards regarding environmental temperature has been a major problem, as modulations are also be affected by the task type, complexity, workload, duration, and previous experience with the task. To bypass this attentional and thermoregulatory problem, we focused on the body rather than environmental temperature. Specifically, we measured tympanic, forehead, finger and environmental temperatures accompanied by a battery of attentional tasks. We considered a 10 min baseline period wherein subjects were instructed to sit and relax, followed by three attentional tasks: a continuous performance task (CPT), a flanker task (FT) and a counting task (CT). Using multiple linear regression models, we evaluated which variable(s) were the best predictors of performance. The results showed a decrement in finger temperature due to instruction and task engagement that was absent when the subject was instructed to relax. No changes were observed in tympanic or forehead temperatures, while the environmental temperature remained almost constant for each subject. Specifically, the magnitude of the change in finger temperature was the best predictor of performance in all three attentional tasks. The results presented here suggest that finger temperature can be used as a predictor of alertness, as it predicted performance in attentional tasks better than environmental temperature. These findings strongly support that peripheral temperature can be used as a tool to prevent unsafe behaviors and accidents.

Multiple stressors, nonlinear effects and the implications of climate change impacts on marine coastal ecosystems.

PubMed

Hewitt, Judi E; Ellis, Joanne I; Thrush, Simon F

2016-08-01

Global climate change will undoubtedly be a pressure on coastal marine ecosystems, affecting not only species distributions and physiology but also ecosystem functioning. In the coastal zone, the environmental variables that may drive ecological responses to climate change include temperature, wave energy, upwelling events and freshwater inputs, and all act and interact at a variety of spatial and temporal scales. To date, we have a poor understanding of how climate-related environmental changes may affect coastal marine ecosystems or which environmental variables are likely to produce priority effects. Here we use time series data (17 years) of coastal benthic macrofauna to investigate responses to a range of climate-influenced variables including sea-surface temperature, southern oscillation indices (SOI, Z4), wind-wave exposure, freshwater inputs and rainfall. We investigate responses from the abundances of individual species to abundances of functional traits and test whether species that are near the edge of their tolerance to another stressor (in this case sedimentation) may exhibit stronger responses. The responses we observed were all nonlinear and some exhibited thresholds. While temperature was most frequently an important predictor, wave exposure and ENSO-related variables were also frequently important and most ecological variables responded to interactions between environmental variables. There were also indications that species sensitive to another stressor responded more strongly to weaker climate-related environmental change at the stressed site than the unstressed site. The observed interactions between climate variables, effects on key species or functional traits, and synergistic effects of additional anthropogenic stressors have important implications for understanding and predicting the ecological consequences of climate change to coastal ecosystems. © 2015 John Wiley & Sons Ltd.

Appraisal of Environmental Influence on Radon Variability in 10 m deep Borehole at Ghuttu, Northwest Himalaya, India

NASA Astrophysics Data System (ADS)

Arora, B.. R.; Choubey, V. M.; Barbosa, S. M.

2009-04-01

Wadia Institute of Himalayan Geology (WIHG) has recently established the first Indian Multi-Parametric Geophysical Observatory (MPGO) at Ghuttu (30.53 N, 78.74 E) in Garhwal Himalayas (Uttarakhand), India to study the earthquake precursors in integrated manner. Given the rationale and significance of this inter-disciplinary approach, the paper with the help of recorded radon time series shall illustrate the complex time variability that needs to be quantified in terms of influencing environmental factors before residual field can be used to search anticipated earthquake precursory signals. Monitoring of 222radon (Rn) is carried out using a gamma ray radon monitoring probe based on 1.5" x 1.5" NaI scintillation. Measurement of radon concentration at 15 min interval has been done at 10m depth in air column above the variable water level in a 68m deep borehole together with simultaneous recordings of ground water level and environmental variables such as atmospheric pressure, temperature, rain fall etc. Apart from strong seasonal cycle in Rn concentration, with high values in summer (July to September) and low values in the winter months (January to March), the most obvious feature in the time series is the distinct nature of daily variation pattern. Four types of daily variations observed are a) positive peaks, b) negative peaks and c) sinusoidal peaks and d) long intervals when daily variations are conspicuously absent, particularly in winter and rainy season. Examination and correlation with environmental factors has revealed that when surface atmospheric temperature is well below the water temperature in borehole (later is constant around 19oC in all seasons) temperature gradients are not conducive to set up the convection currents for the emanation of radon to surface, thus explaining the absence of daily variation in radon concentration in winter. During the rainy season, following continuous rainfalls, once the soil/rocks are saturated with water radon concentrations show fair stability. Long pauses in rainfall give jerky variability during rainy season with no clear pattern of daily variation. During rest of the seasons when surface temperature are always higher that water temperature, the nature of observed pattern can be reconciled in terms of the form and amplitude of daily progression in temperature gradient. An accurate description of the effect of environmental variables is essential if we to wish decipher information related to stress/strain accumulation.

Genome scanning for detecting adaptive genes along environmental gradients in the Japanese conifer, Cryptomeria japonica.

PubMed

Tsumura, Y; Uchiyama, K; Moriguchi, Y; Ueno, S; Ihara-Ujino, T

2012-12-01

Local adaptation is important in evolutionary processes and speciation. We used multiple tests to identify several candidate genes that may be involved in local adaptation from 1026 loci in 14 natural populations of Cryptomeria japonica, the most economically important forestry tree in Japan. We also studied the relationships between genotypes and environmental variables to obtain information on the selective pressures acting on individual populations. Outlier loci were mapped onto a linkage map, and the positions of loci associated with specific environmental variables are considered. The outlier loci were not randomly distributed on the linkage map; linkage group 11 was identified as a genomic island of divergence. Three loci in this region were also associated with environmental variables such as mean annual temperature, daily maximum temperature, maximum snow depth, and so on. Outlier loci identified with high significance levels will be essential for conservation purposes and for future work on molecular breeding.

Effects of environmental variables on invasive amphibian activity: Using model selection on quantiles for counts

USGS Publications Warehouse

Muller, Benjamin J.; Cade, Brian S.; Schwarzkoph, Lin

2018-01-01

Many different factors influence animal activity. Often, the value of an environmental variable may influence significantly the upper or lower tails of the activity distribution. For describing relationships with heterogeneous boundaries, quantile regressions predict a quantile of the conditional distribution of the dependent variable. A quantile count model extends linear quantile regression methods to discrete response variables, and is useful if activity is quantified by trapping, where there may be many tied (equal) values in the activity distribution, over a small range of discrete values. Additionally, different environmental variables in combination may have synergistic or antagonistic effects on activity, so examining their effects together, in a modeling framework, is a useful approach. Thus, model selection on quantile counts can be used to determine the relative importance of different variables in determining activity, across the entire distribution of capture results. We conducted model selection on quantile count models to describe the factors affecting activity (numbers of captures) of cane toads (Rhinella marina) in response to several environmental variables (humidity, temperature, rainfall, wind speed, and moon luminosity) over eleven months of trapping. Environmental effects on activity are understudied in this pest animal. In the dry season, model selection on quantile count models suggested that rainfall positively affected activity, especially near the lower tails of the activity distribution. In the wet season, wind speed limited activity near the maximum of the distribution, while minimum activity increased with minimum temperature. This statistical methodology allowed us to explore, in depth, how environmental factors influenced activity across the entire distribution, and is applicable to any survey or trapping regime, in which environmental variables affect activity.

Environmental criteria for human comfort. A study of the related literature

NASA Technical Reports Server (NTRS)

Jacobson, I. D.

1974-01-01

The data presented has for the most part been extracted from existing in-house and memoranda reports. The variables considered are motion, noise, temperature and pressure. The report is broken down into chapters for each of the environmental variables and criteria proposed based on the existing literature.

Solar array model corrections from Mars Pathfinder lander data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ewell, R.C.; Burger, D.R.

1997-12-31

The MESUR solar array power model initially assumed values for input variables. After landing early surface variables such as array tilt and azimuth or early environmental variables such as array temperature can be corrected. Correction of later environmental variables such as tau versus time, spectral shift, dust deposition, and UV darkening is dependent upon time, on-board science instruments, and ability to separate effects of variables. Engineering estimates had to be made for additional shadow losses and Voc sensor temperature corrections. Some variations had not been expected such as tau versus time of day, and spectral shift versus time of day.more » Additions needed to the model are thermal mass of lander petal and correction between Voc sensor and temperature sensor. Conclusions are: the model works well; good battery predictions are difficult; inclusion of Isc and Voc sensors was valuable; and the IMP and MAE science experiments greatly assisted the data analysis and model correction.« less

[Effects of environmental factors on β diversity of zooplankton community in thermal discharge seawaters near Guohua Power Plant in Xiangshan Bay, Zhejiang, China].

PubMed

Zhu, Yi-feng; Dai, Mei-xia; Zhou, Xiao-hong; Lin, Xia; Mao, Shuo-qian; Yan, Xiao-jun

2015-08-01

Zooplankton samples were seasonally collected at 10 stations in thermal discharge seawaters near Guohua Power Plant in Xiangshan Bay. The abundance data from these samples were pooled and further combined with field environmental factors, then generalised dissimilarity modelling (GDM) was used to explore the effects of environmental factors on β diversity of zooplankton community. The results showed that altogether 95 species of zooplankton belonging to 14 taxa were found. In these taxa, small zooplankton with 62.6% of abundance was the main taxa, while copepods dominated in adult groups, which abundance accounted for 35.3%. According to Whittaker's definition and additive partition, a diversity accounted for 36.3% and β diversity 63.7%. Environmental factors explained 43.8% of β diversity, and geographical distance between sampling sites had no effect on β diversity. However, there were still 19.9% of β diversity remained to be explained. After GDM fitting, there were nine environmental variables affecting zooplankton β diversity and explaining 68.8% of β diversity. The variables contributing to β diversity from high to low were seasonal water temperature, dissolved oxygen, seawater temperature increment, conductivity, suspended particulate matter, salinity, transparency, water depth and redox potential, respectively. Seasonal water temperature, dissolved oxygen and seawater temperature increment were the most important factors for driving β diversity changes, and accounted for 23.9%, 13.7% and 9.7% of absolute contribution to the interpretable portion of the β diversity, respectively. When seasonal water temperature, dissolved oxygen and seawater temperature increment were below 25 °C, greater than 5 mg · L(-1) and over 1 °C, respectively, β diversity rapidly increased with the increasing variable gradients. Furthermore, other predictors had little effect on β diversity.

Statistical modelling for precision agriculture: A case study in optimal environmental schedules for Agaricus Bisporus production via variable domain functional regression.

PubMed

Panayi, Efstathios; Peters, Gareth W; Kyriakides, George

2017-01-01

Quantifying the effects of environmental factors over the duration of the growing process on Agaricus Bisporus (button mushroom) yields has been difficult, as common functional data analysis approaches require fixed length functional data. The data available from commercial growers, however, is of variable duration, due to commercial considerations. We employ a recently proposed regression technique termed Variable-Domain Functional Regression in order to be able to accommodate these irregular-length datasets. In this way, we are able to quantify the contribution of covariates such as temperature, humidity and water spraying volumes across the growing process, and for different lengths of growing processes. Our results indicate that optimal oxygen and temperature levels vary across the growing cycle and we propose environmental schedules for these covariates to optimise overall yields.

Statistical modelling for precision agriculture: A case study in optimal environmental schedules for Agaricus Bisporus production via variable domain functional regression

PubMed Central

Panayi, Efstathios; Kyriakides, George

2017-01-01

Quantifying the effects of environmental factors over the duration of the growing process on Agaricus Bisporus (button mushroom) yields has been difficult, as common functional data analysis approaches require fixed length functional data. The data available from commercial growers, however, is of variable duration, due to commercial considerations. We employ a recently proposed regression technique termed Variable-Domain Functional Regression in order to be able to accommodate these irregular-length datasets. In this way, we are able to quantify the contribution of covariates such as temperature, humidity and water spraying volumes across the growing process, and for different lengths of growing processes. Our results indicate that optimal oxygen and temperature levels vary across the growing cycle and we propose environmental schedules for these covariates to optimise overall yields. PMID:28961254

Effect of the environmental stimuli upon the human body in winter outdoor thermal environment.

PubMed

Kurazumi, Yoshihito; Kondo, Emi; Ishii, Jin; Sakoi, Tomonori; Fukagawa, Kenta; Bolashikov, Zhecho Dimitrov; Tsuchikawa, Tadahiro; Matsubara, Naoki; Horikoshi, Tetsumi

2013-01-01

In order to manage the outdoor thermal environment with regard to human health and the environmental impact of waste heat, quantitative evaluations are indispensable. It is necessary to use a thermal environment evaluation index. The purpose of this paper is to clarify the relationship between the psychological thermal responses of the human body and winter outdoor thermal environment variables. Subjective experiments were conducted in the winter outdoor environment. Environmental factors and human psychological responses were measured. The relationship between the psychological thermal responses of the human body and the outdoor thermal environment index ETFe (enhanced conduction-corrected modified effective temperature) in winter was shown. The variables which influence the thermal sensation vote of the human body are air temperature, long-wave thermal radiation and short-wave solar radiation. The variables that influence the thermal comfort vote of the human body are air temperature, humidity, short-wave solar radiation, long-wave thermal radiation, and heat conduction. Short-wave solar radiation, and heat conduction are among the winter outdoor thermal environment variables that affect psychological responses to heat. The use of thermal environment evaluation indices that comprise short-wave solar radiation and heat conduction in winter outdoor spaces is a valid approach.

Statistical analysis of environmental variability within the CELSS breadboard project's biomass production chamber

NASA Technical Reports Server (NTRS)

Stutte, G. W.; Chetirkin, P. V.; Mackowiak, C. L.; Fortson, R. E.

1993-01-01

Variability in the aerial and root environments of NASA's Breadboard Project's Biomass Production Chamber (BPC) was determined. Data from two lettuce and two potato growouts were utilized. One growout of each crop was conducted prior to separating the upper and lower chambers; the other was subsequent to separation. There were little or no differences in pH, EC, or solution temperature between the upper and lower chamber or within a chamber. Variation in the aerial environment within a chamber was two to three times greater than variation between chambers for air temperature, relative humidity, and PPF. High variability in air velocity, relative to tray position, was observed. Separating the BPC had no effect on PPF, air velocity, solution temperature, pH, or EC. Separation reduced the gradient in air temperature and relative humidity between the upper and lower chambers, but increased the variability within a chamber. Variation between upper and lower chambers was within 5 percent of environmental set-points and of little or no physiological significance. In contrast, the variability within a chamber limits the capability of the BPC to generate statistically reliable data from individual tray treatments at this time.

Compensating for environmental variability in the thermal inertia approach to remote sensing of soil moisture

NASA Technical Reports Server (NTRS)

Idso, S. B.; Jackson, R. D.; Reginato, R. J.

1976-01-01

A procedure is developed for removing data scatter in the thermal-inertia approach to remote sensing of soil moisture which arises from environmental variability in time and space. It entails the utilization of nearby National Weather Service air temperature measurements to normalize measured diurnal surface temperature variations to what they would have been for a day of standard diurnal air temperature variation, arbitrarily assigned to be 18 C. Tests of the procedure's basic premise on a bare loam soil and a crop of alfalfa indicate it to be conceptually sound. It is possible that the technique could also be useful in other thermal-inertia applications, such as lithographic mapping.

Comparison of three models predicting developmental milestones given environmental and individual variation

Treesearch

Estella Gilbert; James A. Powell; Jesse A. Logan; Barbara J. Bentz

2004-01-01

In all organisms, phenotypic variability is an evolutionary stipulation. Because the development of poikilothermic organisms depends directly on the temperature of their habitat, environmental variability is also an integral factor in models of their phenology. In this paper we present two existing phenology models, the distributed delay model and the Sharpe and...

Advances in satellite remote sensing of environmental variables for epidemiological applications.

PubMed

Goetz, S J; Prince, S D; Small, J

2000-01-01

Earth-observing satellites have provided an unprecedented view of the land surface but have been exploited relatively little for the measurement of environmental variables of particular relevance to epidemiology. Recent advances in techniques to recover continuous fields of air temperature, humidity, and vapour pressure deficit from remotely sensed observations have significant potential for disease vector monitoring and related epidemiological applications. We report on the development of techniques to map environmental variables with relevance to the prediction of the relative abundance of disease vectors and intermediate hosts. Improvements to current methods of obtaining information on vegetation properties, canopy and surface temperature and soil moisture over large areas are also discussed. Algorithms used to measure these variables incorporate visible, near-infrared and thermal infrared radiation observations derived from time series of satellite-based sensors, focused here primarily but not exclusively on the Advanced Very High Resolution Radiometer (AVHRR) instruments. The variables compare favourably with surface measurements over a broad array of conditions at several study sites, and maps of retrieved variables captured patterns of spatial variability comparable to, and locally more accurate than, spatially interpolated meteorological observations. Application of multi-temporal maps of these variables are discussed in relation to current epidemiological research on the distribution and abundance of some common disease vectors.

What do foraging wasps optimize in a variable environment, energy investment or body temperature?

PubMed

Kovac, Helmut; Stabentheiner, Anton; Brodschneider, Robert

2015-11-01

Vespine wasps (Vespula sp.) are endowed with a pronounced ability of endothermic heat production. To show how they balance energetics and thermoregulation under variable environmental conditions, we measured the body temperature and respiration of sucrose foragers (1.5 M, unlimited flow) under variable ambient temperature (T a = 20-35 °C) and solar radiation (20-570 W m(-2)). Results revealed a graduated balancing of metabolic efforts with thermoregulatory needs. The thoracic temperature in the shade depended on ambient temperature, increasing from ~37 to 39 °C. However, wasps used solar heat gain to regulate their thorax temperature at a rather high level at low T a (mean T thorax ~ 39 °C). Only at high T a they used solar heat to reduce their metabolic rate remarkably. A high body temperature accelerated the suction speed and shortened foraging time. As the costs of foraging strongly depended on duration, the efficiency could be significantly increased with a high body temperature. Heat gain from solar radiation enabled the wasps to enhance foraging efficiency at high ambient temperature (T a = 30 °C) by up to 63 %. The well-balanced change of economic strategies in response to environmental conditions minimized costs of foraging and optimized energetic efficiency.

Daily rhythmicity of the thermoregulatory responses of locally adapted Brazilian sheep in a semiarid environment.

PubMed

da Silva, Wilma Emanuela; Leite, Jacinara Hody Gurgel Morais; de Sousa, José Ernandes Rufino; Costa, Wirton Peixoto; da Silva, Wallace Sostene Tavares; Guilhermino, Magda Maria; Asensio, Luis Alberto Bermejo; Façanha, Débora Andréa Evangelista

2017-07-01

The goal of this study was to evaluate the daily rhythmicity of the thermoregulatory responses of Morada Nova ewes that were raised in a semiarid environment. The experiment was conducted during the dry season. Data were collected from 5:00 a.m. to 4:00 a.m.. Samples were taken over the course of 8 days, with a 1-week interval between sampling periods. During each day that the data were collected, animals were measured once an hour for 24 h in an area directly exposed to solar radiation. The environment was characterized by measuring the following variables: air temperature (TA), relative humidity (RH), Black Globe Humidity Index (BGHI), radiant heat load (RHL), and wind speed (WS). Physiological variables that were measured included rectal temperature (RT, °C), respiratory rate (RR, breaths/min), surface temperature (ST, °C), and sweating rate (SR, g m 2  h -1 ). We observed that RT, RR, and ST increased as environmental conditions became more stressful. Specifically, environmental conditions became more stressful as RHL, air temperature, and BGHI increased, while RH decreased. All physiological variables of the animals were strongly affected by the time of the day: environmental variables changed drastically between nighttime and noon. Physiological parameters increased sharply from the morning (7:00 a.m.-10:00 a.m.) until noon (11:00 a.m.-2:00 p.m.), except for sweating rate. After noon, these variables began to drop until nighttime (11:00 p.m.-6:00 am), and values of the main physiological indexes were stable during this period. The Morada Nova breed exhibited daily cyclic variations in thermoregulatory responses. Evaporative heat loss mechanisms were triggered during the most stressful times of the day. The first mechanism that animals used was panting, which was an immediate response to environmental heat stress. Cutaneous evaporation had a slower response mechanism to environmental heat stress. Homeothermy conditions were restored to the animals at approximately 5:00 p.m.; however, these findings confirm the importance of providing environmental protection during critical periods of the day, even for locally adapted breeds. These responses suggest that the use of thermal storage allowed the animals to achieve equilibrium with the environment and maintain a stable body temperature.

Daily rhythmicity of the thermoregulatory responses of locally adapted Brazilian sheep in a semiarid environment

NASA Astrophysics Data System (ADS)

da Silva, Wilma Emanuela; Leite, Jacinara Hody Gurgel Morais; de Sousa, José Ernandes Rufino; Costa, Wirton Peixoto; da Silva, Wallace Sostene Tavares; Guilhermino, Magda Maria; Asensio, Luis Alberto Bermejo; Façanha, Débora Andréa Evangelista

2017-07-01

The goal of this study was to evaluate the daily rhythmicity of the thermoregulatory responses of Morada Nova ewes that were raised in a semiarid environment. The experiment was conducted during the dry season. Data were collected from 5:00 a.m. to 4:00 a.m.. Samples were taken over the course of 8 days, with a 1-week interval between sampling periods. During each day that the data were collected, animals were measured once an hour for 24 h in an area directly exposed to solar radiation. The environment was characterized by measuring the following variables: air temperature (TA), relative humidity (RH), Black Globe Humidity Index (BGHI), radiant heat load (RHL), and wind speed (WS). Physiological variables that were measured included rectal temperature (RT, °C), respiratory rate (RR, breaths/min), surface temperature (ST, °C), and sweating rate (SR, g m2 h-1). We observed that RT, RR, and ST increased as environmental conditions became more stressful. Specifically, environmental conditions became more stressful as RHL, air temperature, and BGHI increased, while RH decreased. All physiological variables of the animals were strongly affected by the time of the day: environmental variables changed drastically between nighttime and noon. Physiological parameters increased sharply from the morning (7:00 a.m.-10:00 a.m.) until noon (11:00 a.m.-2:00 p.m.), except for sweating rate. After noon, these variables began to drop until nighttime (11:00 p.m.-6:00 am), and values of the main physiological indexes were stable during this period. The Morada Nova breed exhibited daily cyclic variations in thermoregulatory responses. Evaporative heat loss mechanisms were triggered during the most stressful times of the day. The first mechanism that animals used was panting, which was an immediate response to environmental heat stress. Cutaneous evaporation had a slower response mechanism to environmental heat stress. Homeothermy conditions were restored to the animals at approximately 5:00 p.m.; however, these findings confirm the importance of providing environmental protection during critical periods of the day, even for locally adapted breeds. These responses suggest that the use of thermal storage allowed the animals to achieve equilibrium with the environment and maintain a stable body temperature.

Remotely-sensed, nocturnal, dew point correlates with malaria transmission in Southern Province, Zambia: a time-series study

PubMed Central

2014-01-01

Background Plasmodium falciparum transmission has decreased significantly in Zambia in the last decade. The malaria transmission is influenced by environmental variables. Incorporation of environmental variables in models of malaria transmission likely improves model fit and predicts probable trends in malaria disease. This work is based on the hypothesis that remotely-sensed environmental factors, including nocturnal dew point, are associated with malaria transmission and sustain foci of transmission during the low transmission season in the Southern Province of Zambia. Methods Thirty-eight rural health centres in Southern Province, Zambia were divided into three zones based on transmission patterns. Correlations between weekly malaria cases and remotely-sensed nocturnal dew point, nocturnal land surface temperature as well as vegetation indices and rainfall were evaluated in time-series analyses from 2012 week 19 to 2013 week 36. Zonal as well as clinic-based, multivariate, autoregressive, integrated, moving average (ARIMAX) models implementing environmental variables were developed to model transmission in 2011 week 19 to 2012 week 18 and forecast transmission in 2013 week 37 to week 41. Results During the dry, low transmission season significantly higher vegetation indices, nocturnal land surface temperature and nocturnal dew point were associated with the areas of higher transmission. Environmental variables improved ARIMAX models. Dew point and normalized differentiated vegetation index were significant predictors and improved all zonal transmission models. In the high-transmission zone, this was also seen for land surface temperature. Clinic models were improved by adding dew point and land surface temperature as well as normalized differentiated vegetation index. The mean average error of prediction for ARIMAX models ranged from 0.7 to 33.5%. Forecasts of malaria incidence were valid for three out of five rural health centres; however, with poor results at the zonal level. Conclusions In this study, the fit of ARIMAX models improves when environmental variables are included. There is a significant association of remotely-sensed nocturnal dew point with malaria transmission. Interestingly, dew point might be one of the factors sustaining malaria transmission in areas of general aridity during the dry season. PMID:24927747

Remotely-sensed, nocturnal, dew point correlates with malaria transmission in Southern Province, Zambia: a time-series study.

PubMed

Nygren, David; Stoyanov, Cristina; Lewold, Clemens; Månsson, Fredrik; Miller, John; Kamanga, Aniset; Shiff, Clive J

2014-06-13

Plasmodium falciparum transmission has decreased significantly in Zambia in the last decade. The malaria transmission is influenced by environmental variables. Incorporation of environmental variables in models of malaria transmission likely improves model fit and predicts probable trends in malaria disease. This work is based on the hypothesis that remotely-sensed environmental factors, including nocturnal dew point, are associated with malaria transmission and sustain foci of transmission during the low transmission season in the Southern Province of Zambia. Thirty-eight rural health centres in Southern Province, Zambia were divided into three zones based on transmission patterns. Correlations between weekly malaria cases and remotely-sensed nocturnal dew point, nocturnal land surface temperature as well as vegetation indices and rainfall were evaluated in time-series analyses from 2012 week 19 to 2013 week 36. Zonal as well as clinic-based, multivariate, autoregressive, integrated, moving average (ARIMAX) models implementing environmental variables were developed to model transmission in 2011 week 19 to 2012 week 18 and forecast transmission in 2013 week 37 to week 41. During the dry, low transmission season significantly higher vegetation indices, nocturnal land surface temperature and nocturnal dew point were associated with the areas of higher transmission. Environmental variables improved ARIMAX models. Dew point and normalized differentiated vegetation index were significant predictors and improved all zonal transmission models. In the high-transmission zone, this was also seen for land surface temperature. Clinic models were improved by adding dew point and land surface temperature as well as normalized differentiated vegetation index. The mean average error of prediction for ARIMAX models ranged from 0.7 to 33.5%. Forecasts of malaria incidence were valid for three out of five rural health centres; however, with poor results at the zonal level. In this study, the fit of ARIMAX models improves when environmental variables are included. There is a significant association of remotely-sensed nocturnal dew point with malaria transmission. Interestingly, dew point might be one of the factors sustaining malaria transmission in areas of general aridity during the dry season.

Living Membranes as Environmental Detectors

DTIC Science & Technology

2016-02-19

followed. Initial studies were conducted for 30 days of storage at room temperature and 4⁰C. Results indicate that the living membrane is stable...4⁰C or room temperature in wet or lyophilized form. Freeze-dried mat Wet pellicle 4oC RT 4oC RT Figure 13: Stability of RFP Living Membrane...physically robust format able to withstand extremes of temperature , humidity, and other environmental variables The living membrane systems under

Impact of change in climate and policy from 1988 to 2007 on environmental and microbial variables at the time series station Boknis Eck, Baltic Sea

NASA Astrophysics Data System (ADS)

Hoppe, H.-G.; Giesenhagen, H. C.; Koppe, R.; Hansen, H.-P.; Gocke, K.

2012-12-01

Phytoplankton and bacteria are sensitive indicators of environmental change. The temporal development of these key organisms was monitored from 1988 to the end of 2007 at the time series station Boknis Eck in the Western Baltic Sea. This period was characterized by the adaption of the Baltic Sea ecosystem to changes in the environmental conditions caused by the collapse and conversion of the political system in the Southern and Eastern Border States, accompanied by the general effects of global climate change. Measured variables were chlorophyll, primary production, bacteria number, -biomass and -production, glucose turnover rate, macro-nutrients, pH, temperature and salinity. Negative trends with time were recorded for chlorophyll, the bacterial variables, nitrate, ammonia, phosphate, silicate, oxygen and salinity while temperature, pH, and the ratio between bacteria numbers and chlorophyll increased. The strongest reductions with time occurred for the annual maximum values, e.g. for chlorophyll during the spring bloom or for nitrate during winter, while the annual minimum values remained more stable. In deep water above sediment the negative trends of oxygen, nitrate, phosphate and bacterial variables as well as the positive trend of temperature were similar to those in the surface while the trends of salinity, ammonia and silicate were opposite to those in the surface. Decreasing oxygen even in the surface layer was of particular interest because it suggested enhanced recycling of nutrients from the deep hypoxic zones to the surface by vertical mixing. In the long run all variables correlated positively with temperature, except chlorophyll and salinity. Salinity correlated negatively with all bacterial variables as well as precipitation and positively with chlorophyll. Surprisingly, bacterial variables did not correlate with chlorophyll which may be inherent with the time lag between the peaks of phytoplankton and bacteria during spring. Compared to the 20-yr averages of the environmental and microbial variables, the strongest negative deviations of corresponding annual averages were measured about ten years after political change for nitrate and bacterial secondary production (~ -60%), followed by chlorophyll (-50%) and bacterial biomass (-40%). Considering the circulation of surface currents in the Baltic Sea we conclude that the improved management of water resources after 1989 together with the trends of the climate variables salinity and temperature were responsible for the observed patterns of the microbial variables at the Boknis Eck time series station.

Gross mismatch between thermal tolerances and environmental temperatures in a tropical freshwater snail: climate warming and evolutionary implications.

PubMed

Polgar, Gianluca; Khang, Tsung Fei; Chua, Teddy; Marshall, David J

2015-01-01

The relationship between acute thermal tolerance and habitat temperature in ectotherm animals informs about their thermal adaptation and is used to assess thermal safety margins and sensitivity to climate warming. We studied this relationship in an equatorial freshwater snail (Clea nigricans), belonging to a predominantly marine gastropod lineage (Neogastropoda, Buccinidae). We found that tolerance of heating and cooling exceeded average daily maximum and minimum temperatures, by roughly 20°C in each case. Because habitat temperature is generally assumed to be the main selective factor acting on the fundamental thermal niche, the discordance between thermal tolerance and environmental temperature implies trait conservation following 'in situ' environmental change, or following novel colonisation of a thermally less-variable habitat. Whereas heat tolerance could relate to an historical association with the thermally variable and extreme marine intertidal fringe zone, cold tolerance could associate with either an ancestral life at higher latitudes, or represent adaptation to cooler, higher-altitudinal, tropical lotic systems. The broad upper thermal safety margin (difference between heat tolerance and maximum environmental temperature) observed in this snail is grossly incompatible with the very narrow safety margins typically found in most terrestrial tropical ectotherms (insects and lizards), and hence with the emerging prediction that tropical ectotherms, are especially vulnerable to environmental warming. A more comprehensive understanding of climatic vulnerability of animal ectotherms thus requires greater consideration of taxonomic diversity, ecological transition and evolutionary history. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effects of environment on Arctica islandica shell formation and architecture

NASA Astrophysics Data System (ADS)

Milano, Stefania; Nehrke, Gernot; Wanamaker, Alan D., Jr.; Ballesta-Artero, Irene; Brey, Thomas; Schöne, Bernd R.

2017-03-01

Mollusks record valuable information in their hard parts that reflect ambient environmental conditions. For this reason, shells can serve as excellent archives to reconstruct past climate and environmental variability. However, animal physiology and biomineralization, which are often poorly understood, can make the decoding of environmental signals a challenging task. Many of the routinely used shell-based proxies are sensitive to multiple different environmental and physiological variables. Therefore, the identification and interpretation of individual environmental signals (e.g., water temperature) often is particularly difficult. Additional proxies not influenced by multiple environmental variables or animal physiology would be a great asset in the field of paleoclimatology. The aim of this study is to investigate the potential use of structural properties of Arctica islandica shells as an environmental proxy. A total of 11 specimens were analyzed to study if changes of the microstructural organization of this marine bivalve are related to environmental conditions. In order to limit the interference of multiple parameters, the samples were cultured under controlled conditions. Three specimens presented here were grown at two different water temperatures (10 and 15 °C) for multiple weeks and exposed only to ambient food conditions. An additional eight specimens were reared under three different dietary regimes. Shell material was analyzed with two techniques; (1) confocal Raman microscopy (CRM) was used to quantify changes of the orientation of microstructural units and pigment distribution, and (2) scanning electron microscopy (SEM) was used to detect changes in microstructural organization. Our results indicate that A. islandica microstructure is not sensitive to changes in the food source and, likely, shell pigment are not altered by diet. However, seawater temperature had a statistically significant effect on the orientation of the biomineral. Although additional work is required, the results presented here suggest that the crystallographic orientation of biomineral units of A. islandica may serve as an alternative and independent proxy for seawater temperature.

40 CFR 53.55 - Test for effect of variations in power line voltage and ambient temperature.

Code of Federal Regulations, 2010 CFR

2010-07-01

... measurement accuracy. (iv) Coefficient of variability measurement accuracy. (v) Ambient air temperature... line voltage and ambient temperature. 53.55 Section 53.55 Protection of Environment ENVIRONMENTAL... power line voltage and ambient temperature. (a) Overview. (1) This test procedure is a combined...

Can temperature explain the latitudinal gradient of ulcerative colitis? Cohort of Norway

PubMed Central

2013-01-01

Background Incidence and prevalence of ulcerative colitis follow a north–south (latitudinal) gradient and increases northwards at the northern hemisphere or southwards at the southern hemisphere. The disease has increased during the last decades. The temporal trend has been explained by the hygiene hypothesis, but few parallel explanations exist for the spatial variability. Many factors are linked to latitude such as climate. Our purpose was to investigate the association between variables governing the climate and prospectively identified patients. Methods In this study, we used a subset of the population-based Cohort of Norway (n = 80412) where 370 prevalent cases of ulcerative colitis were identified through self-reported medication. The meteorological and climatic variables temperature, precipitation, and altitude were recorded from weather stations of the Norwegian Meteorological Institute. Summer temperature was used to capture environmental temperature. Results Summer temperature was significantly related to the prevalence of ulcerative colitis. For each one-degree increase in temperature the odds for ulcerative colitis decreased with about 9% (95% CI: 3%-15%). None of the other climatic factors were significantly associated to the risk of ulcerative colitis. Contextual variables did not change the association to the prevalence of ulcerative colitis. Conclusions The present results show that the prevalence of ulcerative colitis is associated to summer temperature. Our speculation is that summer temperature works as an instrumental variable for the effect of microbial species richness on the development of ulcerative colitis. Environmental temperature is one of the main forces governing microbial species richness and the microbial composition of the commensal gut flora is known to be an important part in the process leading to ulcerative colitis. PMID:23724802

Genetic variation in heat-stress tolerance among South American Drosophila populations.

PubMed

Fallis, Lindsey C; Fanara, Juan Jose; Morgan, Theodore J

2011-10-01

Spatial or temporal differences in environmental variables, such as temperature, are ubiquitous in nature and impose stress on organisms. This is especially true for organisms that are isothermal with the environment, such as insects. Understanding the means by which insects respond to temperature and how they will react to novel changes in environmental temperature is important for understanding the adaptive capacity of populations and to predict future trajectories of evolutionary change. The organismal response to heat has been identified as an important environmental variable for insects that can dramatically influence life history characters and geographic range. In the current study we surveyed the amount of variation in heat tolerance among Drosophila melanogaster populations collected at diverse sites along a latitudinal gradient in Argentina (24°-38°S). This is the first study to quantify heat tolerance in South American populations and our work demonstrates that most of the populations surveyed have abundant within-population phenotypic variation, while still exhibiting significant variation among populations. The one exception was the most heat tolerant population that comes from a climate exhibiting the warmest annual mean temperature. All together our results suggest there is abundant genetic variation for heat-tolerance phenotypes within and among natural populations of Drosophila and this variation has likely been shaped by environmental temperature.

Ecological determinants of mean family age of angiosperm trees in forest communities in China

NASA Astrophysics Data System (ADS)

Qian, Hong; Chen, Shengbin

2016-06-01

Species assemblage in a local community is determined by the interplay of evolutionary and ecological processes. The Tropical Niche Conservatism hypothesis proposes mechanisms underlying patterns of biodiversity in biological communities along environmental gradients. This hypothesis predicts that, among other things, clades in areas with warm or wet environments are, on average, older than those in areas with cold or dry environments. Focusing on angiosperm trees in forests, this study tested the age-related prediction of the Tropical Niche Conservatism hypothesis. We related the mean family age of angiosperm trees in 57 local forests from across China with 23 current and paleo-environmental variables, which included all major temperature- and precipitation-related variables. Our study shows that the mean family age of angiosperm trees in local forests was positively correlated with temperature and precipitation. This finding is consistent with the age-related prediction of the Tropical Niche Conservatism hypothesis. Approximately 85% of the variance in the mean family age of angiosperm trees was explained by temperature-related variables, and 81% of the variance in the mean family age of angiosperm trees was explained by precipitation-related variables. Climatic conditions at the Last Glacial Maximum did not explain additional variation in mean family age after accounting for current environmental conditions.

Landscape genomics of Sphaeralcea ambigua in the Mojave Desert: a multivariate, spatially-explicit approach to guide ecological restoration

USGS Publications Warehouse

Shryock, Daniel F.; Havrilla, Caroline A.; DeFalco, Lesley; Esque, Todd C.; Custer, Nathan; Wood, Troy E.

2015-01-01

Local adaptation influences plant species’ responses to climate change and their performance in ecological restoration. Fine-scale physiological or phenological adaptations that direct demographic processes may drive intraspecific variability when baseline environmental conditions change. Landscape genomics characterize adaptive differentiation by identifying environmental drivers of adaptive genetic variability and mapping the associated landscape patterns. We applied such an approach to Sphaeralcea ambigua, an important restoration plant in the arid southwestern United States, by analyzing variation at 153 amplified fragment length polymorphism loci in the context of environmental gradients separating 47 Mojave Desert populations. We identified 37 potentially adaptive loci through a combination of genome scan approaches. We then used a generalized dissimilarity model (GDM) to relate variability in potentially adaptive loci with spatial gradients in temperature, precipitation, and topography. We identified non-linear thresholds in loci frequencies driven by summer maximum temperature and water stress, along with continuous variation corresponding to temperature seasonality. Two GDM-based approaches for mapping predicted patterns of local adaptation are compared. Additionally, we assess uncertainty in spatial interpolations through a novel spatial bootstrapping approach. Our study presents robust, accessible methods for deriving spatially-explicit models of adaptive genetic variability in non-model species that will inform climate change modelling and ecological restoration.

Effect of the Environmental Stimuli upon the Human Body in Winter Outdoor Thermal Environment

PubMed Central

Kurazumi, Yoshihito; Kondo, Emi; Ishii, Jin; Sakoi, Tomonori; Fukagawa, Kenta; Bolashikov, Zhecho Dimitrov; Tsuchikawa, Tadahiro; Matsubara, Naoki; Horikoshi, Tetsumi

2013-01-01

In order to manage the outdoor thermal environment with regard to human health and the environmental impact of waste heat, quantitative evaluations are indispensable. It is necessary to use a thermal environment evaluation index. The purpose of this paper is to clarify the relationship between the psychological thermal responses of the human body and winter outdoor thermal environment variables. Subjective experiments were conducted in the winter outdoor environment. Environmental factors and human psychological responses were measured. The relationship between the psychological thermal responses of the human body and the outdoor thermal environment index ETFe (enhanced conduction-corrected modified effective temperature) in winter was shown. The variables which influence the thermal sensation vote of the human body are air temperature, long-wave thermal radiation and short-wave solar radiation. The variables that influence the thermal comfort vote of the human body are air temperature, humidity, short-wave solar radiation, long-wave thermal radiation, and heat conduction. Short-wave solar radiation, and heat conduction are among the winter outdoor thermal environment variables that affect psychological responses to heat. The use of thermal environment evaluation indices that comprise short-wave solar radiation and heat conduction in winter outdoor spaces is a valid approach. PMID:23861691

A multi-scale comparison of trait linkages to environmental and spatial variables in fish communities across a large freshwater lake.

PubMed

Strecker, Angela L; Casselman, John M; Fortin, Marie-Josée; Jackson, Donald A; Ridgway, Mark S; Abrams, Peter A; Shuter, Brian J

2011-07-01

Species present in communities are affected by the prevailing environmental conditions, and the traits that these species display may be sensitive indicators of community responses to environmental change. However, interpretation of community responses may be confounded by environmental variation at different spatial scales. Using a hierarchical approach, we assessed the spatial and temporal variation of traits in coastal fish communities in Lake Huron over a 5-year time period (2001-2005) in response to biotic and abiotic environmental factors. The association of environmental and spatial variables with trophic, life-history, and thermal traits at two spatial scales (regional basin-scale, local site-scale) was quantified using multivariate statistics and variation partitioning. We defined these two scales (regional, local) on which to measure variation and then applied this measurement framework identically in all 5 study years. With this framework, we found that there was no change in the spatial scales of fish community traits over the course of the study, although there were small inter-annual shifts in the importance of regional basin- and local site-scale variables in determining community trait composition (e.g., life-history, trophic, and thermal). The overriding effects of regional-scale variables may be related to inter-annual variation in average summer temperature. Additionally, drivers of fish community traits were highly variable among study years, with some years dominated by environmental variation and others dominated by spatially structured variation. The influence of spatial factors on trait composition was dynamic, which suggests that spatial patterns in fish communities over large landscapes are transient. Air temperature and vegetation were significant variables in most years, underscoring the importance of future climate change and shoreline development as drivers of fish community structure. Overall, a trait-based hierarchical framework may be a useful conservation tool, as it highlights the multi-scaled interactive effect of variables over a large landscape.

Assessment of high to low frequency variations of isoprene emission rates using a neural network approach

NASA Astrophysics Data System (ADS)

Boissard, C.; Chervier, F.; Dutot, A. L.

2007-08-01

Using a statistical approach based on artificial neural networks, an emission algorithm (ISO_LF) accounting for high (instantaneous) to low (seasonal) frequency variations was developed for isoprene. ISO_LF was optimised using an isoprene emission data base (ISO-DB) specifically designed for this work. ISO-DB consists of 1321 emission rates collected in the literature, together with 34 environmental variables, measured or assessed using NCDC (National Climatic Data Center) or NCEP (National Centers for Environmental Predictions) meteorological databases. ISO-DB covers a large variety of emitters (25 species) and environmental conditions (10° S to 60° N). When only instantaneous environmental regressors (air temperature and photosynthetic active radiation, PAR) were used, a maximum of 60% of the overall isoprene variability was assessed and the highest emissions were underestimated. Considering a total of 9 high (instantaneous) to low (up to 3 weeks) frequency regressors, ISO_LF accounts for up to 91% of the isoprene emission variability, whatever the emission range, species or climate. Diurnal and seasonal variations are correctly reproduced for textit{Ulex europaeus} with a maximum factor of discrepancy of 4. ISO-LF was found to be mainly sensitive to air temperature cumulated over 3 weeks T21 and to instantaneous light L0 and air temperature T0 variations. T21, T0 and L0 only accounts for 76% of the overall variability. The use of ISO-LF for non stored monoterpene emissions was shown to give poor results.

Impact of change in climate and policy from 1988 to 2007 on environmental and microbial variables at the time series station Boknis Eck, Baltic Sea

NASA Astrophysics Data System (ADS)

Hoppe, H.-G.; Giesenhagen, H. C.; Koppe, R.; Hansen, H.-P.; Gocke, K.

2013-07-01

Phytoplankton and bacteria are sensitive indicators of environmental change. The temporal development of these key organisms was monitored from 1988 to the end of 2007 at the time series station Boknis Eck in the western Baltic Sea. This period was characterized by the adaption of the Baltic Sea ecosystem to changes in the environmental conditions caused by the conversion of the political system in the southern and eastern border states, accompanied by the general effects of global climate change. Measured variables were chlorophyll, primary production, bacteria number, -biomass and -production, glucose turnover rate, macro-nutrients, pH, temperature and salinity. Negative trends with time were recorded for chlorophyll, bacteria number, bacterial biomass and bacterial production, nitrate, ammonia, phosphate, silicate, oxygen and salinity while temperature, pH, and the ratio between bacteria numbers and chlorophyll increased. Strongest reductions with time occurred for the annual maximum values, e.g. for chlorophyll during the spring bloom or for nitrate during winter, while the annual minimum values remained more stable. In deep water above sediment the negative trends of oxygen, nitrate, phosphate and bacterial variables as well as the positive trend of temperature were similar to those in the surface while the trends of salinity, ammonia and silicate were opposite to those in the surface. Decreasing oxygen, even in the surface layer, was of particular interest because it suggested enhanced recycling of nutrients from the deep hypoxic zones to the surface by vertical mixing. The long-term seasonal patterns of all variables correlated positively with temperature, except chlorophyll and salinity. Salinity correlated negatively with all bacterial variables (as well as precipitation) and positively with chlorophyll. Surprisingly, bacterial variables did not correlate with chlorophyll, which may be inherent with the time lag between the peaks of phytoplankton and bacteria during spring. Compared to the 20-yr averages of the environmental and microbial variables, the strongest negative deviations of corresponding annual averages were measured about ten years after political change for nitrate and bacterial secondary production (~ -60%), followed by chlorophyll (-50%) and bacterial biomass (-40%). Considering the circulation of surface currents in the Baltic Sea we interpret the observed patterns of the microbial variables at the Boknis Eck time series station as a consequence of the improved management of water resources after 1989 and - to a minor extent - the trends of the climate variables salinity and temperature.

Disruption, not displacement: Environmental variability and temporary migration in Bangladesh

PubMed Central

Gray, Clark; Yunus, Mohammad; Emch, Michael

2018-01-01

Mass migration is one of the most concerning potential outcomes of global climate change. Recent research into environmentally induced migration suggests that relationship is much more complicated than originally posited by the ‘environmental refugee’ hypothesis. Climate change is likely to increase migration in some cases and reduce it in others, and these movements will more often be temporary and short term than permanent and long term. However, few large-sample studies have examined the evolution of temporary migration under changing environmental conditions. To address this gap, we measure the extent to which temperature, precipitation, and flooding can predict temporary migration in Matlab, Bangladesh. Our analysis incorporates high-frequency demographic surveillance data, a discrete time event history approach, and a range of sociodemographic and contextual controls. This approach reveals that migration declines immediately after flooding but quickly returns to normal. In contrast, optimal precipitation and high temperatures have sustained positive effects on temporary migration that persist over one to two year periods. Building on previous studies of long-term migration, these results challenge the common assumption that flooding, precipitation extremes and high temperatures will consistently increase temporary migration. Instead, our results are consistent with a livelihoods interpretation of environmental migration in which households draw on a range of strategies to cope with environmental variability. PMID:29375196

Disruption, not displacement: Environmental variability and temporary migration in Bangladesh.

PubMed

Call, Maia A; Gray, Clark; Yunus, Mohammad; Emch, Michael

2017-09-01

Mass migration is one of the most concerning potential outcomes of global climate change. Recent research into environmentally induced migration suggests that relationship is much more complicated than originally posited by the 'environmental refugee' hypothesis. Climate change is likely to increase migration in some cases and reduce it in others, and these movements will more often be temporary and short term than permanent and long term. However, few large-sample studies have examined the evolution of temporary migration under changing environmental conditions. To address this gap, we measure the extent to which temperature, precipitation, and flooding can predict temporary migration in Matlab, Bangladesh. Our analysis incorporates high-frequency demographic surveillance data, a discrete time event history approach, and a range of sociodemographic and contextual controls. This approach reveals that migration declines immediately after flooding but quickly returns to normal. In contrast, optimal precipitation and high temperatures have sustained positive effects on temporary migration that persist over one to two year periods. Building on previous studies of long-term migration, these results challenge the common assumption that flooding, precipitation extremes and high temperatures will consistently increase temporary migration. Instead, our results are consistent with a livelihoods interpretation of environmental migration in which households draw on a range of strategies to cope with environmental variability.

Self-discharge analysis and characterization of supercapacitors for environmentally powered wireless sensor network applications

NASA Astrophysics Data System (ADS)

Yang, Hengzhao; Zhang, Ying

2011-10-01

A new approach is presented to characterize the variable leakage resistance, a parameter in the variable leakage resistance model we developed to model supercapacitors used in environmentally powered wireless sensor network applications. Based on an analysis of the supercapacitor terminal behavior during the self-discharge, the variable leakage resistance is modeled as a function of the supercapacitor terminal voltage instead of the self-discharge time, which is more practical for an environmentally powered wireless sensor node. The new characterization approach is implemented and validated using MATLAB Simulink with a 10 F supercapacitor as an example. In addition, effects of initial voltages and temperatures on the supercapacitor self-discharge rate and the variable leakage resistance value are explored.

Spatialization of Brazilian pig production: relationship between productive, physical, environmental, and socio-economic variables.

PubMed

da Silva, Isabel C M; Bremm, Bárbara; Teixeira, Jennifer L; Costa, Nathalia S; Barcellos, Júlio O J; Braccini, José; Cesconeto, Robson J; McManus, Concepta

2017-06-01

Brazilian pig production spans over a large territory encompassing regions of different climatic and socio-economic realities. Production, physical, socio-economic, and environmental data were used to characterize pig production in the country. Multivariate analysis evaluated indices including number productivity, production levels, and income from pigs, together with the average area of pig farm and socio-economic variables such as municipal human development index, technical guidance received from agricultural cooperatives and industrial companies, number of family farms, and offtake; and finally, environmental variables: latitude, longitude, annual temperature range, solar radiation index, as well as temperature and humidity index. The Southern region has the largest herd, number of pigs sold/sow, and offtake rate (p < 0.05), followed by the Midwest and Southeast. No significant correlations were seen between production rates and productivity with the socio-economic and environmental variables in the regions of Brazil. Production indexes, productivity, and offtake rate discriminated Northeast and Midwest and Northeast and Southeast regions. The Northern region, with a large area, has few and far-between farms that rear pigs for subsistence. The Northeast region has large herds, but low productivity. Number of slaughtered pigs has been variable over the past three decades, with few states responsible for maintaining high production in Brazil. However, the activity can be effective in any region of the country with technology and technical assistance adapted to regional characteristics.

Detection of genomic loci associated with environmental variables using generalized linear mixed models.

PubMed

Lobréaux, Stéphane; Melodelima, Christelle

2015-02-01

We tested the use of Generalized Linear Mixed Models to detect associations between genetic loci and environmental variables, taking into account the population structure of sampled individuals. We used a simulation approach to generate datasets under demographically and selectively explicit models. These datasets were used to analyze and optimize GLMM capacity to detect the association between markers and selective coefficients as environmental data in terms of false and true positive rates. Different sampling strategies were tested, maximizing the number of populations sampled, sites sampled per population, or individuals sampled per site, and the effect of different selective intensities on the efficiency of the method was determined. Finally, we apply these models to an Arabidopsis thaliana SNP dataset from different accessions, looking for loci associated with spring minimal temperature. We identified 25 regions that exhibit unusual correlations with the climatic variable and contain genes with functions related to temperature stress. Copyright © 2014 Elsevier Inc. All rights reserved.

Environmental Risk Factors for the Incidence of American Cutaneous Leishmaniasis in a Sub-Andean Zone of Colombia (Chaparral, Tolima)

PubMed Central

Valderrama-Ardila, Carlos; Alexander, Neal; Ferro, Cristina; Cadena, Horacio; Marín, Dairo; Holford, Theodore R.; Munstermann, Leonard E.; Ocampo, Clara B.

2010-01-01

Environmental risk factors for cutaneous leishmaniasis were investigated for the largest outbreak recorded in Colombia. The outbreak began in 2003 in Chaparral, and in the following five years produced 2,313 cases in a population of 56,228. Candidate predictor variables were land use, elevation, and climatic variables such as mean temperature and precipitation. Spatial analysis showed that incidence of cutaneous leishmaniasis was higher in townships with mean temperatures in the middle of the county's range. Incidence was independently associated with higher coverage with forest or shrubs (2.6% greater for each additional percent coverage, 95% credible interval [CI] = 0.5–4.9%), and lower population density (22% lower for each additional 100 persons/km2, 95% CI = 7–41%). The extent of forest or shrub coverage did not show major changes over time. These findings confirmed the roles of climate and land use in leishmaniasis transmission. However, environmental variables were not sufficient to explain the spatial variation in incidence. PMID:20134000

Effects of environmental variables on surface temperature of breeding adult female northern elephant seals, Mirounga angustirostris, and pups.

PubMed

Codde, Sarah A; Allen, Sarah G; Houser, Dorian S; Crocker, Daniel E

2016-10-01

Pinnipeds spend extended periods of time on shore during breeding, and some temperate species retreat to the water if exposed to high ambient temperatures. However, female northern elephant seals (Mirounga angustirostris) with pups generally avoid the water, presumably to minimize risks to pups or male harassment. Little is known about how ambient temperature affects thermoregulation of well insulated females while on shore. We used a thermographic camera to measure surface temperature (T s ) of 100 adult female elephant seals and their pups during the breeding season at Point Reyes National Seashore, yielding 782 thermograms. Environmental variables were measured by an onsite weather station. Environmental variables, especially solar radiation and ambient temperature, were the main determinants of mean and maximum T s of both females and pups. An average of 16% of the visible surface of both females and pups was used as thermal windows to facilitate heat loss and, for pups, this area increased with solar radiation. Thermal window area of females increased with mean T s until approximately 26°C and then declined. The T s of both age classes were warmer than ambient temperature and had a large thermal gradient with the environment (female mean 11.2±0.2°C; pup mean 14.2±0.2°C). This large gradient suggests that circulatory adjustments to bypass blubber layers were sufficient to allow seals to dissipate heat under most environmental conditions. We observed the previously undescribed behavior of females and pups in the water and determined that solar radiation affected this behavior. This may have been possible due to the calm waters at the study site, which reduced the risk of neonates drowning. These results may predict important breeding habitat features for elephant seals as solar radiation and ambient temperatures change in response to changing climate. Published by Elsevier Ltd.

Influence of environmental temperature on 40 km cycling time-trial performance.

PubMed

Peiffer, Jeremiah J; Abbiss, Chris R

2011-06-01

The purpose of this study was to examine the effect of environmental temperature on variability in power output, self-selected pacing strategies, and performance during a prolonged cycling time trial. Nine trained male cyclists randomly completed four 40 km cycling time trials in an environmental chamber at 17°C, 22°C, 27°C, and 32°C (40% RH). During the time trials, heart rate, core body temperature, and power output were recorded. The variability in power output was assessed with the use of exposure variation analysis. Mean 40 km power output was significantly lower during 32°C (309 ± 35 W) compared with 17°C (329 ± 31 W), 22°C (324 ± 34 W), and 27°C (322 ± 32 W). In addition, greater variability in power production was observed at 32°C compared with 17°C, as evidenced by a lower (P = .03) standard deviation of the exposure variation matrix (2.9 ± 0.5 vs 3.5 ± 0.4 units, respectively). Core temperature was greater (P < .05) at 32°C compared with 17°C and 22°C from 30 to 40 km, and the rate of rise in core temperature throughout the 40 km time trial was greater (P < .05) at 32°C (0.06 ± 0.04°C·km-1) compared with 17°C (0.05 ± 0.05°C·km-1). This study showed that time-trial performance is reduced under hot environmental conditions, and is associated with a shift in the composition of power output. These finding provide insight into the control of pacing strategies during exercise in the heat.

Multi-scale approach to the environmental factors effects on spatio-temporal variability of Chironomus salinarius (Diptera: Chironomidae) in a French coastal lagoon

NASA Astrophysics Data System (ADS)

Cartier, V.; Claret, C.; Garnier, R.; Fayolle, S.; Franquet, E.

2010-03-01

The complexity of the relationships between environmental factors and organisms can be revealed by sampling designs which consider the contribution to variability of different temporal and spatial scales, compared to total variability. From a management perspective, a multi-scale approach can lead to time-saving. Identifying environmental patterns that help maintain patchy distribution is fundamental in studying coastal lagoons, transition zones between continental and marine waters characterised by great environmental variability on spatial and temporal scales. They often present organic enrichment inducing decreased species richness and increased densities of opportunist species like C hironomus salinarius, a common species that tends to swarm and thus constitutes a nuisance for human populations. This species is dominant in the Bolmon lagoon, a French Mediterranean coastal lagoon under eutrophication. Our objective was to quantify variability due to both spatial and temporal scales and identify the contribution of different environmental factors to this variability. The population of C. salinarius was sampled from June 2007 to June 2008 every two months at 12 sites located in two areas of the Bolmon lagoon, at two different depths, with three sites per area-depth combination. Environmental factors (temperature, dissolved oxygen both in sediment and under water surface, sediment organic matter content and grain size) and microbial activities (i.e. hydrolase activities) were also considered as explanatory factors of chironomid densities and distribution. ANOVA analysis reveals significant spatial differences regarding the distribution of chironomid larvae for the area and the depth scales and their interaction. The spatial effect is also revealed for dissolved oxygen (water), salinity and fine particles (area scale), and for water column depth. All factors but water column depth show a temporal effect. Spearman's correlations highlight the seasonal effect (temperature, dissolved oxygen in sediment and water) as well as the effect of microbial activities on chironomid larvae. Our results show that a multi-scale approach identifies patchy distribution, even when there is relative environmental homogeneity.

Environmental variation, vegetation distribution, carbon dynamics and water/energy exchange at high latitudes

USGS Publications Warehouse

McGuire, A.D.; Wirth, C.; Apps, M.; Beringer, J.; Clein, J.; Epstein, H.; Kicklighter, D.W.; Bhatti, J.; Chapin, F. S.; De Groot, B.; Efremov, D.; Eugster, W.; Fukuda, M.; Gower, T.; Hinzman, L.; Huntley, B.; Jia, G.J.; Kasischke, E.; Melillo, J.; Romanovsky, V.; Shvidenko, A.; Vaganov, E.; Walker, D.

2002-01-01

The responses of high latitude ecosystems to global change involve complex interactions among environmental variables, vegetation distribution, carbon dynamics, and water and energy exchange. These responses may have important consequences for the earth system. In this study, we evaluated how vegetation distribution, carbon stocks and turnover, and water and energy exchange are related to environmental variation spanned by the network of the IGBP high latitude transects. While the most notable feature of the high latitude transects is that they generally span temperature gradients from southern to northern latitudes, there are substantial differences in temperature among the transects. Also, along each transect temperature co-varies with precipitation and photosynthetically active radiation, which are also variable among the transects. Both climate and disturbance interact to influence latitudinal patterns of vegetation and soil carbon storage among the transects, and vegetation distribution appears to interact with climate to determine exchanges of heat and moisture in high latitudes. Despite limitations imposed by the data we assembled, the analyses in this study have taken an important step toward clarifying the complexity of interactions among environmental variables, vegetation distribution, carbon stocks and turnover, and water and energy exchange in high latitude regions. This study reveals the need to conduct coordinated global change studies in high latitudes to further elucidate how interactions among climate, disturbance, and vegetation distribution influence carbon dynamics and water and energy exchange in high latitudes.

Below room temperature: How the photocatalytic activity of dense and mesoporous TiO2 coatings is affected

NASA Astrophysics Data System (ADS)

Cedillo-González, Erika Iveth; Riccò, Raffaele; Costacurta, Stefano; Siligardi, Cristina; Falcaro, Paolo

2018-03-01

Different parameters such as morphology, porosity, crystalline phase or doping agents affect the self-cleaning performance of photocatalytic TiO2-based coatings. However, also environmental conditions have been found to play a major role on the photocatalytic self-cleaning property. Substrate temperature is a significant environmental variable that can drastically affect this process. This variable becomes of great importance especially for outdoor applications: many self-cleaning photocatalytic materials have been designed to be exposed to outdoor environments and consequently, can be exposed to variable temperatures depending on the season of the year and the typical weather of the geographical zone. Thus, understanding the influence of the most common outdoor temperatures on the self-cleaning performance of TiO2-based coatings is essential for the fabrication of any kind of photocatalytic self-cleaning materials (fabricated by coating technology) that is expected to be subjected to outdoor environments. In this work, the photocatalytic activity was studied by Fourier Transformed Infrared (FTIR) Spectroscopy varying the temperature in the 0 to 30 °C range for dense and mesoporous TiO2 coatings. The temperature conditions at which these coatings present better performances were identified, providing a deeper insight for the practical application of TiO2-based self-cleaning coatings.

Ecology and geography of human monkeypox case occurrences across Africa.

PubMed

Ellis, Christine K; Carroll, Darin S; Lash, Ryan R; Peterson, A Townsend; Damon, Inger K; Malekani, Jean; Formenty, Pierre

2012-04-01

As ecologic niche modeling (ENM) evolves as a tool in spatial epidemiology and public health, selection of the most appropriate and informative environmental data sets becomes increasingly important. Here, we build on a previous ENM analysis of the potential distribution of human monkeypox in Africa by refining georeferencing criteria and using more-diverse environmental data to identify environmental parameters contributing to monkeypox distributional ecology. Significant environmental variables include annual precipitation, several temperature-related variables, primary productivity, evapotranspiration, soil moisture, and pH. The potential distribution identified with this set of variables was broader than that identified in previous analyses but does not include areas recently found to hold monkeypox in southern Sudan. Our results emphasize the importance of selecting the most appropriate and informative environmental data sets for ENM analyses in pathogen transmission mapping.

Application of factor analysis to the water quality in reservoirs

NASA Astrophysics Data System (ADS)

Silva, Eliana Costa e.; Lopes, Isabel Cristina; Correia, Aldina; Gonçalves, A. Manuela

2017-06-01

In this work we present a Factor Analysis of chemical and environmental variables of the water column and hydro-morphological features of several Portuguese reservoirs. The objective is to reduce the initial number of variables, keeping their common characteristics. Using the Factor Analysis, the environmental variables measured in the epilimnion and in the hypolimnion, together with the hydromorphological characteristics of the dams were reduced from 63 variables to only 13 factors, which explained a total of 83.348% of the variance in the original data. After performing rotation using the Varimax method, the relations between the factors and the original variables got clearer and more explainable, which provided a Factor Analysis model for these environmental variables using 13 varifactors: Water quality and distance to the source, Hypolimnion chemical composition, Sulfite-reducing bacteria and nutrients, Coliforms and faecal streptococci, Reservoir depth, Temperature, Location, among other factors.

Temperature-Dependent Growth Modeling of Environmental and Clinical Legionella pneumophila Multilocus Variable-Number Tandem-Repeat Analysis (MLVA) Genotypes

PubMed Central

Sharaby, Yehonatan; Rodríguez-Martínez, Sarah; Oks, Olga; Pecellin, Marina; Mizrahi, Hila; Peretz, Avi; Brettar, Ingrid; Höfle, Manfred G.

2017-01-01

ABSTRACT Legionella pneumophila causes waterborne infections resulting in severe pneumonia. High-resolution genotyping of L. pneumophila isolates can be achieved by multiple-locus variable-number tandem-repeat analysis (MLVA). Recently, we found that different MLVA genotypes of L. pneumophila dominated different sites in a small drinking-water network, with a genotype-related temperature and abundance regime. The present study focuses on understanding the temperature-dependent growth kinetics of the genotypes that dominated the water network. Our aim was to model mathematically the influence of temperature on the growth kinetics of different environmental and clinical L. pneumophila genotypes and to compare it with the influence of their ecological niches. Environmental strains showed a distinct temperature preference, with significant differences among the growth kinetics of the three studied genotypes (Gt4, Gt6, and Gt15). Gt4 strains exhibited superior growth at lower temperatures (25 and 30°C), while Gt15 strains appeared to be best adapted to relatively higher temperatures (42 and 45°C). The temperature-dependent growth traits of the environmental genotypes were consistent with their distribution and temperature preferences in the water network. Clinical isolates exhibited significantly higher growth rates and reached higher maximal cell densities at 37°C and 42°C than the environmental strains. Further research on the growth preferences of L. pneumophila clinical and environmental genotypes will result in a better understanding of their ecological niches in drinking-water systems as well as in the human body. IMPORTANCE Legionella pneumophila is a waterborne pathogen that threatens humans in developed countries. The bacteria inhabit natural and man-made freshwater environments. Here we demonstrate that different environmental L. pneumophila genotypes have different temperature-dependent growth kinetics. Moreover, Legionella strains that belong to the same species but were isolated from environmental and clinical sources possess adaptations for growth at different temperatures. These growth preferences may influence the bacterial colonization at specific ecological niches within the drinking-water network. Adaptations for growth at human body temperatures may facilitate the abilities of some L. pneumophila strains to infect and cause illness in humans. Our findings may be used as a tool to improve Legionella monitoring in drinking-water networks. Risk assessment models for predicting the risk of legionellosis should take into account not only Legionella concentrations but also the temperature-dependent growth kinetics of the isolates. PMID:28159784

Do walleye pollock exhibit flexibility in where or when they spawn based on variability in water temperature?

NASA Astrophysics Data System (ADS)

Bacheler, Nathan M.; Ciannelli, Lorenzo; Bailey, Kevin M.; Bartolino, Valerio

2012-06-01

Environmental variability is increasingly recognized as a primary determinant of year-class strength of marine fishes by directly or indirectly influencing egg and larval development, growth, and survival. Here we examined the role of annual water temperature variability in determining when and where walleye pollock (Theragra chalcogramma) spawn in the eastern Bering Sea. Walleye pollock spawning was examined using both long-term ichthyoplankton data (N=19 years), as well as with historical spatially explicit, foreign-reported, commercial catch data occurring during the primary walleye pollock spawning season (February-May) each year (N=22 years in total). We constructed variable-coefficient generalized additive models (GAMs) to relate the spatially explicit egg or adult catch-per-unit-effort (CPUE) to predictor variables including spawning stock biomass, season, position, and water temperature. The adjusted R2 value was 63.1% for the egg CPUE model and 35.5% for the adult CPUE model. Both egg and adult GAMs suggest that spawning progresses seasonally from Bogoslof Island in February and March to Outer Domain waters between the Pribilof and Unimak Islands by May. Most importantly, walleye pollock egg and adult CPUE was predicted to generally increase throughout the study area as mean annual water temperature increased. These results suggest low interannual variability in the spatial and temporal dynamics of walleye pollock spawning regardless of changes in environmental conditions, at least at the spatial scale examined in this study and within the time frame of decades.

Seasonal variation in the biocontrol efficiency of bacterial wilt is driven by temperature-mediated changes in bacterial competitive interactions.

PubMed

Wei, Zhong; Huang, Jianfeng; Yang, Tianjie; Jousset, Alexandre; Xu, Yangchun; Shen, Qirong; Friman, Ville-Petri

2017-10-01

Microbe-based biocontrol applications hold the potential to become an efficient way to control plant pathogen disease outbreaks in the future. However, their efficiency is still very variable, which could be due to their sensitivity to the abiotic environmental conditions.Here, we assessed how environmental temperature variation correlates with ability of Ralstonia pickettii , an endophytic bacterial biocontrol agent, to suppress the Ralstonia solanacearum pathogen during different tomato crop seasons in China.We found that suppression of the pathogen was highest when the seasonal mean temperatures were around 20 °C and rapidly decreased with increasing mean crop season temperatures. Interestingly, low levels of disease incidence did not correlate with low pathogen or high biocontrol agent absolute densities. Instead, the biocontrol to pathogen density ratio was a more important predictor of disease incidence levels between different crop seasons. To understand this mechanistically, we measured the growth and strength of competition between the biocontrol agent and the pathogen over a naturally occurring temperature gradient in vitro . We found that the biocontrol strain grew relatively faster at low temperature ranges, and the pathogen at high temperature ranges, and that similar to field experiments, pathogen suppression peaked at 20 °C.Together, our results suggest that temperature-mediated changes in the strength of bacterial competition could potentially explain the variable R. solanacearum biocontrol outcomes between different crop seasons in China. Synthesis and applications . Our results suggest that abiotic environmental conditions, such as temperature, can affect the efficacy of biocontrol applications. Thus, in order to develop more consistent biocontrol applications in the future, we might need to find and isolate bacterial strains that can retain their functionality regardless of the changing environmental conditions.

Host tolerance, not symbiont tolerance, determines the distribution of coral species in relation to their environment at a Central Pacific atoll

NASA Astrophysics Data System (ADS)

Wicks, L. C.; Gardner, J. P. A.; Davy, S. K.

2012-06-01

Tolerance of environmental variables differs between corals and their dinoflagellate symbionts ( Symbiodinium spp.), controlling the holobiont's (host and symbiont combined) resilience to environmental stress. However, the ecological role that environmental variables play in holobiont distribution remains poorly understood. We compared the drivers of symbiont and coral species distributions at Palmyra Atoll, a location with a range of reef environments from low to high sediment concentrations (1-52 g dry weight m-2 day-1). We observed uniform holobiont partnerships across the atoll (e.g. Montipora spp. with Symbiodinium type C15 at all sites). Multivariate analysis revealed that field-based estimates of settling sediment predominantly explained the spatial variation of coral species among sites ( P < 0.01). However, none of the environmental variables measured (sedimentation, temperature, chlorophyll concentration, salinity) affected symbiont distribution. The discord between environmental variables and symbiont distributions suggests that the symbionts are physiologically tolerant of the variable environmental regime across this location and that the distribution of different host-symbiont combinations present is largely dependent on coral rather than Symbiodinium physiology. The data highlight the importance of host tolerance to environmental stressors, which should be considered simultaneously with symbiont sensitivity when considering the impact of variations in environmental conditions on coral communities.

Effects of environmental temperature on the gut microbial communities of tadpoles.

PubMed

Kohl, Kevin D; Yahn, Jeremiah

2016-05-01

Numerous studies have investigated the effects of diet, phylogeny and immune status on the gut microbial communities of animals. Most of these studies are conducted on endotherms, especially mammals, which maintain constant body temperature in the face of environmental temperature variability. However, the majority of animals and vertebrates are ectotherms, which often experience fluctuations in body temperature as a result of their environment. While there have been several studies investigating the gut microbial diversity of ectotherms, we lack an understanding of how environmental temperature affects these communities. Here, we used high-throughput sequencing to inventory the gut microbial communities of tadpoles exposed to cool (18°C) or warm (28°C) temperature treatments. We found that temperature significantly impacted the community structure and membership of the tadpole gut. Specifically, tadpoles in the warm treatment exhibited higher abundances of the phylum Planctomycetes and the genus Mycobacterium. These results may be due to the direct effects of temperature, or mediated through changes in host physiology. Given that environmental temperatures are expected to increase due to global climate change, understanding the effects of temperature on the diversity and function of gut microbial communities is critical. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

The role of environmental variables on Aedes albopictus biology and chikungunya epidemiology

PubMed Central

Waldock, Joanna; Chandra, Nastassya L; Lelieveld, Jos; Proestos, Yiannis; Michael, Edwin; Christophides, George; Parham, Paul E

2013-01-01

Aedes albopictus is a vector of dengue and chikungunya viruses in the field, along with around 24 additional arboviruses under laboratory conditions. As an invasive mosquito species, Ae. albopictus has been expanding in geographical range over the past 20 years, although the poleward extent of mosquito populations is limited by winter temperatures. Nonetheless, population densities depend on environmental conditions and since global climate change projections indicate increasing temperatures and altered patterns of rainfall, geographic distributions of previously tropical mosquito species may change. Although mathematical models can provide explanatory insight into observed patterns of disease prevalence in terms of epidemiological and entomological processes, understanding how environmental variables affect transmission is possible only with reliable model parameterisation, which, in turn, is obtained only through a thorough understanding of the relationship between mosquito biology and environmental variables. Thus, in order to assess the impact of climate change on mosquito population distribution and regions threatened by vector-borne disease, a detailed understanding (through a synthesis of current knowledge) of the relationship between climate, mosquito biology, and disease transmission is required, but this process has not yet been undertaken for Ae. albopictus. In this review, the impact of temperature, rainfall, and relative humidity on Ae. albopictus development and survival are considered. Existing Ae. albopictus populations across Europe are mapped with current climatic conditions, considering whether estimates of climatic cutoffs for Ae. albopictus are accurate, and suggesting that environmental thresholds must be calibrated according to the scale and resolution of climate model outputs and mosquito presence data. PMID:23916332

Impact of patient and environmental factors on capillary refill time in adults.

PubMed

Anderson, Bronwyn; Kelly, Anne-Maree; Kerr, Debra; Clooney, Megan; Jolley, Damien

2008-01-01

Capillary refill time (CRT) has been taught as a rapid indicator of circulatory status. The aim of this study was to define normal CRT in the Australian context and the environmental, patient, and drug factors that influence it. This prospective observational study included healthy adults at hospital clinics, workplaces, universities, and community groups. Volunteer participants provided their age, sex, ethnic group, and use of hypertensive or cardiac medications. Capillary refill time, ambient temperature, and patient temperature were recorded in a standard manner. Data were analyzed using descriptive statistics and regression analyses. The 95th percentile was used to define the upper limit of normal. One thousand participants were included; 57% were women, 90% were white, and 21% were taking cardiac medications. The median CRT was 1.9 seconds (95th percentile, 3.5 seconds). The CRT increased 3.3% for each additional decade of age. The CRT was also on average 7% lower in men than in women. The CRT decreased by 1.2% per degree-Celsius rise of ambient temperature, independently of patient's temperature, and decreased by 5% for each degree-Celsius rise in patient temperature, independently of ambient temperature. On multivariant analysis, age, sex, ambient temperature, and patient temperature were statistically significant predictors of CRT, but together explain only 8% of the observed variability. Capillary refill time varies with environmental and patient factors, but these account for only a small proportion of the variability observed. Its suitability as a reliable clinical test is doubtful.

Historical Temperature Variability Affects Coral Response to Heat Stress

PubMed Central

Carilli, Jessica; Donner, Simon D.; Hartmann, Aaron C.

2012-01-01

Coral bleaching is the breakdown of symbiosis between coral animal hosts and their dinoflagellate algae symbionts in response to environmental stress. On large spatial scales, heat stress is the most common factor causing bleaching, which is predicted to increase in frequency and severity as the climate warms. There is evidence that the temperature threshold at which bleaching occurs varies with local environmental conditions and background climate conditions. We investigated the influence of past temperature variability on coral susceptibility to bleaching, using the natural gradient in peak temperature variability in the Gilbert Islands, Republic of Kiribati. The spatial pattern in skeletal growth rates and partial mortality scars found in massive Porites sp. across the central and northern islands suggests that corals subject to larger year-to-year fluctuations in maximum ocean temperature were more resistant to a 2004 warm-water event. In addition, a subsequent 2009 warm event had a disproportionately larger impact on those corals from the island with lower historical heat stress, as indicated by lower concentrations of triacylglycerol, a lipid utilized for energy, as well as thinner tissue in those corals. This study indicates that coral reefs in locations with more frequent warm events may be more resilient to future warming, and protection measures may be more effective in these regions. PMID:22479626

Relating annual increments of the endangered Blanding's turtle plastron growth to climate

PubMed Central

Richard, Monik G; Laroque, Colin P; Herman, Thomas B

2014-01-01

This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration. PMID:24963390

Relating annual increments of the endangered Blanding's turtle plastron growth to climate.

PubMed

Richard, Monik G; Laroque, Colin P; Herman, Thomas B

2014-05-01

This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration.

Coping with daily thermal variability: behavioural performance of an ectotherm model in a warming world.

PubMed

Rojas, José M; Castillo, Simón B; Folguera, Guillermo; Abades, Sebastián; Bozinovic, Francisco

2014-01-01

Global climate change poses one of the greatest threats to species persistence. Most analyses of the potential biological impacts have focused on changes in mean temperature, but changes in thermal variance will also impact organisms and populations. We assessed the effects of acclimation to daily variance of temperature on dispersal and exploratory behavior in the terrestrial isopod Porcellio laevis in an open field. Acclimation treatments were 24 ± 0, 24 ± 4 and 24 ± 8 °C. Because the performance of ectotherms relates nonlinearly to temperature, we predicted that animals acclimated to a higher daily thermal variation should minimize the time exposed in the centre of open field, --i.e. increase the linearity of displacements. Consistent with our prediction, isopods acclimated to a thermally variable environment reduce their exploratory behaviour, hypothetically to minimize their exposure to adverse environmental conditions. This scenario as well as the long latency of animals after releases acclimated to variable environments is consistent with this idea. We suggested that to develop more realistic predictions about the biological impacts of climate change, one must consider the interactions between the mean and variance of environmental temperature on animals' performance.

Coping with Daily Thermal Variability: Behavioural Performance of an Ectotherm Model in a Warming World

PubMed Central

Rojas, José M.; Castillo, Simón B.; Folguera, Guillermo; Abades, Sebastián; Bozinovic, Francisco

2014-01-01

Global climate change poses one of the greatest threats to species persistence. Most analyses of the potential biological impacts have focused on changes in mean temperature, but changes in thermal variance will also impact organisms and populations. We assessed the effects of acclimation to daily variance of temperature on dispersal and exploratory behavior in the terrestrial isopod Porcellio laevis in an open field. Acclimation treatments were 24±0, 24±4 and 24±8°C. Because the performance of ectotherms relates nonlinearly to temperature, we predicted that animals acclimated to a higher daily thermal variation should minimize the time exposed in the centre of open field, – i.e. increase the linearity of displacements. Consistent with our prediction, isopods acclimated to a thermally variable environment reduce their exploratory behaviour, hypothetically to minimize their exposure to adverse environmental conditions. This scenario as well as the long latency of animals after releases acclimated to variable environments is consistent with this idea. We suggested that to develop more realistic predictions about the biological impacts of climate change, one must consider the interactions between the mean and variance of environmental temperature on animals' performance. PMID:25207653

Disentangling the drivers of taxonomic and phylogenetic beta diversities in disturbed and undisturbed subtropical forests

NASA Astrophysics Data System (ADS)

Liu, Jinliang; Qian, Hong; Jin, Yi; Wu, Chuping; Chen, Jianhua; Yu, Shuquan; Wei, Xinliang; Jin, Xiaofeng; Liu, Jiajia; Yu, Mingjian

2016-10-01

Understanding the relative importance of dispersal limitation and environmental filtering processes in structuring the beta diversities of subtropical forests in human disturbed landscapes is still limited. Here we used taxonomic (TBD) and phylogenetic (PBD), including terminal PBD (PBDt) and basal PBD (PBDb), beta diversity indices to quantify the taxonomic and phylogenetic turnovers at different depths of evolutionary history in disturbed and undisturbed subtropical forests. Multiple linear regression model and distance-based redundancy analysis were used to disentangle the relative importance of environmental and spatial variables. Environmental variables were significantly correlated with TBD and PBDt metrics. Temperature and precipitation were major environmental drivers of beta diversity patterns, which explained 7-27% of the variance in TBD and PBDt, whereas the spatial variables independently explained less than 1% of the variation for all forests. The relative importance of environmental and spatial variables differed between disturbed and undisturbed forests (e.g., when Bray-Curtis was used as a beta diversity metric, environmental variable had a significant effect on beta diversity for disturbed forests but had no effect on undisturbed forests). We conclude that environmental filtering plays a more important role than geographical limitation and disturbance history in driving taxonomic and terminal phylogenetic beta diversity.

Disentangling the drivers of taxonomic and phylogenetic beta diversities in disturbed and undisturbed subtropical forests

PubMed Central

Liu, Jinliang; Qian, Hong; Jin, Yi; Wu, Chuping; Chen, Jianhua; Yu, Shuquan; Wei, Xinliang; Jin, Xiaofeng; Liu, Jiajia; Yu, Mingjian

2016-01-01

Understanding the relative importance of dispersal limitation and environmental filtering processes in structuring the beta diversities of subtropical forests in human disturbed landscapes is still limited. Here we used taxonomic (TBD) and phylogenetic (PBD), including terminal PBD (PBDt) and basal PBD (PBDb), beta diversity indices to quantify the taxonomic and phylogenetic turnovers at different depths of evolutionary history in disturbed and undisturbed subtropical forests. Multiple linear regression model and distance-based redundancy analysis were used to disentangle the relative importance of environmental and spatial variables. Environmental variables were significantly correlated with TBD and PBDt metrics. Temperature and precipitation were major environmental drivers of beta diversity patterns, which explained 7–27% of the variance in TBD and PBDt, whereas the spatial variables independently explained less than 1% of the variation for all forests. The relative importance of environmental and spatial variables differed between disturbed and undisturbed forests (e.g., when Bray-Curtis was used as a beta diversity metric, environmental variable had a significant effect on beta diversity for disturbed forests but had no effect on undisturbed forests). We conclude that environmental filtering plays a more important role than geographical limitation and disturbance history in driving taxonomic and terminal phylogenetic beta diversity. PMID:27775021

Environmental factors prevail over dispersal constraints in determining the distribution and assembly of Trichoptera species in mountain lakes.

PubMed

de Mendoza, Guillermo; Ventura, Marc; Catalan, Jordi

2015-07-01

Aiming to elucidate whether large-scale dispersal factors or environmental species sorting prevail in determining patterns of Trichoptera species composition in mountain lakes, we analyzed the distribution and assembly of the most common Trichoptera (Plectrocnemia laetabilis, Polycentropus flavomaculatus, Drusus rectus, Annitella pyrenaea, and Mystacides azurea) in the mountain lakes of the Pyrenees (Spain, France, Andorra) based on a survey of 82 lakes covering the geographical and environmental extremes of the lake district. Spatial autocorrelation in species composition was determined using Moran's eigenvector maps (MEM). Redundancy analysis (RDA) was applied to explore the influence of MEM variables and in-lake, and catchment environmental variables on Trichoptera assemblages. Variance partitioning analysis (partial RDA) revealed the fraction of species composition variation that could be attributed uniquely to either environmental variability or MEM variables. Finally, the distribution of individual species was analyzed in relation to specific environmental factors using binomial generalized linear models (GLM). Trichoptera assemblages showed spatial structure. However, the most relevant environmental variables in the RDA (i.e., temperature and woody vegetation in-lake catchments) were also related with spatial variables (i.e., altitude and longitude). Partial RDA revealed that the fraction of variation in species composition that was uniquely explained by environmental variability was larger than that uniquely explained by MEM variables. GLM results showed that the distribution of species with longitudinal bias is related to specific environmental factors with geographical trend. The environmental dependence found agrees with the particular traits of each species. We conclude that Trichoptera species distribution and composition in the lakes of the Pyrenees are governed predominantly by local environmental factors, rather than by dispersal constraints. For boreal lakes, with similar environmental conditions, a strong role of dispersal capacity has been suggested. Further investigation should address the role of spatial scaling, namely absolute geographical distances constraining dispersal and steepness of environmental gradients at short distances.

Environmental factors prevail over dispersal constraints in determining the distribution and assembly of Trichoptera species in mountain lakes

PubMed Central

de Mendoza, Guillermo; Ventura, Marc; Catalan, Jordi

2015-01-01

Aiming to elucidate whether large-scale dispersal factors or environmental species sorting prevail in determining patterns of Trichoptera species composition in mountain lakes, we analyzed the distribution and assembly of the most common Trichoptera (Plectrocnemia laetabilis, Polycentropus flavomaculatus, Drusus rectus, Annitella pyrenaea, and Mystacides azurea) in the mountain lakes of the Pyrenees (Spain, France, Andorra) based on a survey of 82 lakes covering the geographical and environmental extremes of the lake district. Spatial autocorrelation in species composition was determined using Moran’s eigenvector maps (MEM). Redundancy analysis (RDA) was applied to explore the influence of MEM variables and in-lake, and catchment environmental variables on Trichoptera assemblages. Variance partitioning analysis (partial RDA) revealed the fraction of species composition variation that could be attributed uniquely to either environmental variability or MEM variables. Finally, the distribution of individual species was analyzed in relation to specific environmental factors using binomial generalized linear models (GLM). Trichoptera assemblages showed spatial structure. However, the most relevant environmental variables in the RDA (i.e., temperature and woody vegetation in-lake catchments) were also related with spatial variables (i.e., altitude and longitude). Partial RDA revealed that the fraction of variation in species composition that was uniquely explained by environmental variability was larger than that uniquely explained by MEM variables. GLM results showed that the distribution of species with longitudinal bias is related to specific environmental factors with geographical trend. The environmental dependence found agrees with the particular traits of each species. We conclude that Trichoptera species distribution and composition in the lakes of the Pyrenees are governed predominantly by local environmental factors, rather than by dispersal constraints. For boreal lakes, with similar environmental conditions, a strong role of dispersal capacity has been suggested. Further investigation should address the role of spatial scaling, namely absolute geographical distances constraining dispersal and steepness of environmental gradients at short distances. PMID:26257867

Effect of nesting environment on incubation temperature and hatching success of Morelet's crocodile (Crocodylus moreletii) in an urban lake of Southeastern Mexico.

PubMed

López-Luna, Marco A; Hidalgo-Mihart, Mircea G; Aguirre-León, Gustavo; González-Ramón, Mariana Del C; Rangel-Mendoza, Judith A

2015-01-01

Incubation temperature is an important aspect in terms of biological performance among crocodiles, and several controlled experiments have demonstrated a significant relationship between incubation temperature, success in hatching and survival of hatchlings. However, a few studies have tested these relationships in the wild. The objective of this study was to determine the relationship of nest characteristics and environment (hatch year, nest basal area and height, clutch size, distance to shore line, and vegetation cover), to incubation temperature and hatching success among Morelet's crocodile (Crocodylus moreletii). The study was carried out during the nesting seasons of Morelet's crocodile, from 2007 to 2009 in the Laguna de Las Ilusiones, an urban lake located in Villahermosa, Tabasco, Mexico. We physically characterized 18 nests and inserted a temperature data logger in each nest chamber. At the end of the nesting season and prior to hatching, we recovered the crocodile eggs and data loggers and calculated hatching success, under laboratory conditions. We related the environmental variables of the nest with the mean and fluctuation (standard deviation) of nest temperature, using linear models. We also related the environmental variables affecting the nest, to mean nest temperature and fluctuation in incubation temperature and to hatching success, using linear models. Although we found differences in incubation temperature between nests, mean incubation temperature did not differ between years, but there were differences in nest thermal fluctuation between years. The mean incubation temperature for 11 nests (61.1%) was lower than the suggested Female-Male pivotal temperature (producing 50% of each sex) for this species, and all hatchlings obtained were males. There were no differences in clutch size between years, but hatching success varied. Our study indicates that hatching success depends on certain environmental variables and nest conditions to which the eggs are subjected, including season, nest size and clutch size. We also discuss the importance of the fluctuation of incubation temperature on hatching success and sex determination. Copyright © 2015 Elsevier Ltd. All rights reserved.

Environmental Factors Correlated with the Metabolite Profile of Vitis vinifera cv. Pinot Noir Berry Skins along a European Latitudinal Gradient.

PubMed

Del-Castillo-Alonso, María Ángeles; Castagna, Antonella; Csepregi, Kristóf; Hideg, Éva; Jakab, Gabor; Jansen, Marcel A K; Jug, Tjaša; Llorens, Laura; Mátai, Anikó; Martínez-Lüscher, Johann; Monforte, Laura; Neugart, Susanne; Olejnickova, Julie; Ranieri, Annamaria; Schödl-Hummel, Katharina; Schreiner, Monika; Soriano, Gonzalo; Teszlák, Péter; Tittmann, Susanne; Urban, Otmar; Verdaguer, Dolors; Zipoli, Gaetano; Martínez-Abaigar, Javier; Núñez-Olivera, Encarnación

2016-11-23

Mature berries of Pinot Noir grapevines were sampled across a latitudinal gradient in Europe, from southern Spain to central Germany. Our aim was to study the influence of latitude-dependent environmental factors on the metabolite composition (mainly phenolic compounds) of berry skins. Solar radiation variables were positively correlated with flavonols and flavanonols and, to a lesser extent, with stilbenes and cinnamic acids. The daily means of global and erythematic UV solar radiation over long periods (bud break-veraison, bud break-harvest, and veraison-harvest), and the doses and daily means in shorter development periods (5-10 days before veraison and harvest) were the variables best correlated with the phenolic profile. The ratio between trihydroxylated and monohydroxylated flavonols, which was positively correlated with antioxidant capacity, was the berry skin variable best correlated with those radiation variables. Total flavanols and total anthocyanins did not show any correlation with radiation variables. Air temperature, degree days, rainfall, and aridity indices showed fewer correlations with metabolite contents than radiation. Moreover, the latter correlations were restricted to the period veraison-harvest, where radiation, temperature, and water availability variables were correlated, making it difficult to separate the possible individual effects of each type of variable. The data show that managing environmental factors, in particular global and UV radiation, through cultural practices during specific development periods, can be useful to promote the synthesis of valuable nutraceuticals and metabolites that influence wine quality.

Interaction of temperature and an environmental stressor: Moina macrocopa responds with increased body size, increased lifespan, and increased offspring numbers slightly above its temperature optimum.

PubMed

Engert, Antonia; Chakrabarti, Shumon; Saul, Nadine; Bittner, Michal; Menzel, Ralph; Steinberg, Christian E W

2013-02-01

For organisms, temperature is one of the most important environmental factors and gains increasing importance due to global warming, since increasing temperatures may pose organisms close to their environmental tolerance limits and, thus, they may become more vulnerable to environmental stressors. We analyzed the temperature-dependence of the water-soluble antioxidant capacity of the cladoceran Moina macrocopa and evaluated its life trait variables with temperature (15, 20, 25, 30°C) and humic substance (HS) concentrations (0, 0.18, 0.36, 0.90, 1.79 mM DOC) as stressors. Temperatures below and above the apparent optimum (20°C) reduced the antioxidative capacity. Additions of HSs increased body length, but decreased mean lifespan at 15 and 20°C. There was no clear HS-effect on offspring numbers at 15, 20, and 30°C. At 25°C with increasing HS-concentration, lifespan was extended and offspring numbers increased tremendously, reaching 250% of the control. Although the applied HS preparation possesses estrogenic and antiandrogenic activities, a xenohormone mechanism does not seem plausible for the reproductive increase, because comparable effects did not occur at other temperatures. A more convincing explanation appears to be the mitohormesis hypothesis which states that a certain increase of reactive oxygen production leads to improved health and longevity and, with Moina, also to increased offspring numbers. Our results suggest that at least with the eurythermic M. macrocopa, a temperature above the optimum can be beneficial for several life trait variables, even when combined with a chemical stressor. Temperatures approximately 10°C above its optimum appear to adversely affect the lifespan and reproduction of M. macrocopa. This indicates that this cladoceran species seems to be able to utilize temperature as an ecological resource in a range slightly above its thermal optimum. Copyright © 2012 Elsevier Ltd. All rights reserved.

Association of Day Length and Weather Conditions with Physical Activity Levels in Older Community Dwelling People

PubMed Central

Witham, Miles D.; Donnan, Peter T.; Vadiveloo, Thenmalar; Sniehotta, Falko F.; Crombie, Iain K.; Feng, Zhiqiang; McMurdo, Marion E. T.

2014-01-01

Background Weather is a potentially important determinant of physical activity. Little work has been done examining the relationship between weather and physical activity, and potential modifiers of any relationship in older people. We therefore examined the relationship between weather and physical activity in a cohort of older community-dwelling people. Methods We analysed prospectively collected cross-sectional activity data from community-dwelling people aged 65 and over in the Physical Activity Cohort Scotland. We correlated seven day triaxial accelerometry data with daily weather data (temperature, day length, sunshine, snow, rain), and a series of potential effect modifiers were tested in mixed models: environmental variables (urban vs rural dwelling, percentage of green space), psychological variables (anxiety, depression, perceived behavioural control), social variables (number of close contacts) and health status measured using the SF-36 questionnaire. Results 547 participants, mean age 78.5 years, were included in this analysis. Higher minimum daily temperature and longer day length were associated with higher activity levels; these associations remained robust to adjustment for other significant associates of activity: age, perceived behavioural control, number of social contacts and physical function. Of the potential effect modifier variables, only urban vs rural dwelling and the SF-36 measure of social functioning enhanced the association between day length and activity; no variable modified the association between minimum temperature and activity. Conclusions In older community dwelling people, minimum temperature and day length were associated with objectively measured activity. There was little evidence for moderation of these associations through potentially modifiable health, environmental, social or psychological variables. PMID:24497925

Association of day length and weather conditions with physical activity levels in older community dwelling people.

PubMed

Witham, Miles D; Donnan, Peter T; Vadiveloo, Thenmalar; Sniehotta, Falko F; Crombie, Iain K; Feng, Zhiqiang; McMurdo, Marion E T

2014-01-01

Weather is a potentially important determinant of physical activity. Little work has been done examining the relationship between weather and physical activity, and potential modifiers of any relationship in older people. We therefore examined the relationship between weather and physical activity in a cohort of older community-dwelling people. We analysed prospectively collected cross-sectional activity data from community-dwelling people aged 65 and over in the Physical Activity Cohort Scotland. We correlated seven day triaxial accelerometry data with daily weather data (temperature, day length, sunshine, snow, rain), and a series of potential effect modifiers were tested in mixed models: environmental variables (urban vs rural dwelling, percentage of green space), psychological variables (anxiety, depression, perceived behavioural control), social variables (number of close contacts) and health status measured using the SF-36 questionnaire. 547 participants, mean age 78.5 years, were included in this analysis. Higher minimum daily temperature and longer day length were associated with higher activity levels; these associations remained robust to adjustment for other significant associates of activity: age, perceived behavioural control, number of social contacts and physical function. Of the potential effect modifier variables, only urban vs rural dwelling and the SF-36 measure of social functioning enhanced the association between day length and activity; no variable modified the association between minimum temperature and activity. In older community dwelling people, minimum temperature and day length were associated with objectively measured activity. There was little evidence for moderation of these associations through potentially modifiable health, environmental, social or psychological variables.

Environment, Migratory Tendency, Phylogeny and Basal Metabolic Rate in Birds

PubMed Central

Jetz, Walter; Freckleton, Robert P.; McKechnie, Andrew E.

2008-01-01

Basal metabolic rate (BMR) represents the minimum maintenance energy requirement of an endotherm and has far-reaching consequences for interactions between animals and their environments. Avian BMR exhibits considerable variation that is independent of body mass. Some long-distance migrants have been found to exhibit particularly high BMR, traditionally interpreted as being related to the energetic demands of long-distance migration. Here we use a global dataset to evaluate differences in BMR between migrants and non-migrants, and to examine the effects of environmental variables. The BMR of migrant species is significantly higher than that of non-migrants. Intriguingly, while the elevated BMR of migrants on their breeding grounds may reflect the metabolic machinery required for long-distance movements, an alternative (and statistically stronger) explanation is their occupation of predominantly cold high-latitude breeding areas. Among several environmental predictors, average annual temperature has the strongest effect on BMR, with a 50% reduction associated with a 20°C gradient. The negative effects of temperature variables on BMR hold separately for migrants and non-migrants and are not due their different climatic associations. BMR in migrants shows a much lower degree of phylogenetic inertia. Our findings indicate that migratory tendency need not necessarily be invoked to explain the higher BMR of migrants. A weaker phylogenetic signal observed in migrants supports the notion of strong phenotypic flexibility in this group which facilitates migration-related BMR adjustments that occur above and beyond environmental conditions. In contrast to the findings of previous analyses of mammalian BMR, primary productivity, aridity or precipitation variability do not appear to be important environmental correlates of avian BMR. The strong effects of temperature-related variables and varying phylogenetic effects reiterate the importance of addressing both broad-scale and individual-scale variation for understanding the determinants of BMR. PMID:18810267

Mass mortality of eastern box turtles with upper respiratory disease following atypical cold weather.

PubMed

Agha, Mickey; Price, Steven J; Nowakowski, A Justin; Augustine, Ben; Todd, Brian D

2017-04-20

Emerging infectious diseases cause population declines in many ectotherms, with outbreaks frequently punctuated by periods of mass mortality. It remains unclear, however, whether thermoregulation by ectotherms and variation in environmental temperature is associated with mortality risk and disease progression, especially in wild populations. Here, we examined environmental and body temperatures of free-ranging eastern box turtles Terrapene carolina during a mass die-off coincident with upper respiratory disease. We recorded deaths of 17 turtles that showed clinical signs of upper respiratory disease among 76 adult turtles encountered in Berea, Kentucky (USA), in 2014. Of the 17 mortalities, 11 occurred approximately 14 d after mean environmental temperature dropped 2.5 SD below the 3 mo mean. Partial genomic sequencing of the major capsid protein from 1 sick turtle identified a ranavirus isolate similar to frog virus 3. Turtles that lacked clinical signs of disease had significantly higher body temperatures (23°C) than sick turtles (21°C) during the mass mortality, but sick turtles that survived and recovered eventually warmed (measured by temperature loggers). Finally, there was a significant negative effect of daily environmental temperature deviation from the 3 mo mean on survival, suggesting that rapid decreases in environmental temperature were correlated with mortality. Our results point to a potential role for environmental temperature variation and body temperature in disease progression and mortality risk of eastern box turtles affected by upper respiratory disease. Given our findings, it is possible that colder or more variable environmental temperatures and an inability to effectively thermoregulate are associated with poorer disease outcomes in eastern box turtles.

Evaluating within-population variability in behavior and demography for the adaptive potential of a dispersal-limited species to climate change

USGS Publications Warehouse

Muñoz, David J.; Miller Hesed, Kyle; Grant, Evan H. Campbell; Miller, David A.W.

2016-01-01

Multiple pathways exist for species to respond to changing climates. However, responses of dispersal-limited species will be more strongly tied to ability to adapt within existing populations as rates of environmental change will likely exceed movement rates. Here, we assess adaptive capacity in Plethodon cinereus, a dispersal-limited woodland salamander. We quantify plasticity in behavior and variation in demography to observed variation in environmental variables over a 5-year period. We found strong evidence that temperature and rainfall influence P. cinereus surface presence, indicating changes in climate are likely to affect seasonal activity patterns. We also found that warmer summer temperatures reduced individual growth rates into the autumn, which is likely to have negative demographic consequences. Reduced growth rates may delay reproductive maturity and lead to reductions in size-specific fecundity, potentially reducing population-level persistence. To better understand within-population variability in responses, we examined differences between two common color morphs. Previous evidence suggests that the color polymorphism may be linked to physiological differences in heat and moisture tolerance. We found only moderate support for morph-specific differences for the relationship between individual growth and temperature. Measuring environmental sensitivity to climatic variability is the first step in predicting species' responses to climate change. Our results suggest phenological shifts and changes in growth rates are likely responses under scenarios where further warming occurs, and we discuss possible adaptive strategies for resulting selective pressures.

Environmental Control for Regional Library Facilities. RR-80-3.

ERIC Educational Resources Information Center

King, Richard G., Jr.

This report presents an overview of the damage to library materials caused by uncontrollable environmental variables. The control of atmospheric pollutants, temperature, and humidity are discussed with regard to damage, standards, and the costs of deterioration due to these factors. Twelve references are listed. (FM)

Effects of temporal variation in temperature and density dependence on insect population dynamics

USDA-ARS?s Scientific Manuscript database

Understanding effects of environmental variation on insect populations is important in light of predictions about increasing future climatic variability. In order to understand the effects of changing environmental variation on population dynamics and life history evolution in insects one would need...

Impacts of temperature and lunar day on gene expression profiles during a monthly reproductive cycle in the brooding coral Pocillopora damicornis.

PubMed

Crowder, Camerron M; Meyer, Eli; Fan, Tung-Yung; Weis, Virginia M

2017-08-01

Reproductive timing in brooding corals has been correlated to temperature and lunar irradiance, but the mechanisms by which corals transduce these environmental variables into molecular signals are unknown. To gain insight into these processes, global gene expression profiles in the coral Pocillopora damicornis were examined (via RNA-Seq) across lunar phases and between temperature treatments, during a monthly planulation cycle. The interaction of temperature and lunar day together had the largest influence on gene expression. Mean timing of planulation, which occurred at lunar days 7.4 and 12.5 for 28- and 23°C-treated corals, respectively, was associated with an upregulation of transcripts in individual temperature treatments. Expression profiles of planulation-associated genes were compared between temperature treatments, revealing that elevated temperatures disrupted expression profiles associated with planulation. Gene functions inferred from homologous matches to online databases suggest complex neuropeptide signalling, with calcium as a central mediator, acting through tyrosine kinase and G protein-coupled receptor pathways. This work contributes to our understanding of coral reproductive physiology and the impacts of environmental variables on coral reproductive pathways. © 2017 John Wiley & Sons Ltd.

The impact of environmental factors on marine turtle stranding rates

PubMed Central

Flint, Mark; Limpus, Colin J.; Mills, Paul C.

2017-01-01

Globally, tropical and subtropical regions have experienced an increased frequency and intensity in extreme weather events, ranging from severe drought to protracted rain depressions and cyclones, these coincided with an increased number of marine turtles subsequently reported stranded. This study investigated the relationship between environmental variables and marine turtle stranding. The environmental variables examined in this study, in descending order of importance, were freshwater discharge, monthly mean maximum and minimum air temperatures, monthly average daily diurnal air temperature difference and rainfall for the latitudinal hotspots (-27°, -25°, -23°, -19°) along the Queensland coast as well as for major embayments within these blocks. This study found that marine turtle strandings can be linked to these environmental variables at different lag times (3–12 months), and that cumulative (months added together for maximum lag) and non-cumulative (single month only) effects cause different responses. Different latitudes also showed different responses of marine turtle strandings, both in response direction and timing.Cumulative effects of freshwater discharge in all latitudes resulted in increased strandings 10–12 months later. For latitudes -27°, -25° and -23° non-cumulative effects for discharge resulted in increased strandings 7–12 months later. Latitude -19° had different results for the non-cumulative bay with strandings reported earlier (3–6 months). Monthly mean maximum and minimum air temperatures, monthly average daily diurnal air temperature difference and rainfall had varying results for each examined latitude. This study will allow first responders and resource managers to be better equipped to deal with increased marine turtle stranding rates following extreme weather events. PMID:28771635

Climate and soil attributes determine plant species turnover in global drylands.

PubMed

Ulrich, Werner; Soliveres, Santiago; Maestre, Fernando T; Gotelli, Nicholas J; Quero, José L; Delgado-Baquerizo, Manuel; Bowker, Matthew A; Eldridge, David J; Ochoa, Victoria; Gozalo, Beatriz; Valencia, Enrique; Berdugo, Miguel; Escolar, Cristina; García-Gómez, Miguel; Escudero, Adrián; Prina, Aníbal; Alfonso, Graciela; Arredondo, Tulio; Bran, Donaldo; Cabrera, Omar; Cea, Alex; Chaieb, Mohamed; Contreras, Jorge; Derak, Mchich; Espinosa, Carlos I; Florentino, Adriana; Gaitán, Juan; Muro, Victoria García; Ghiloufi, Wahida; Gómez-González, Susana; Gutiérrez, Julio R; Hernández, Rosa M; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Mau, Rebecca L; Hughes, Frederic Mendes; Miriti, Maria; Monerris, Jorge; Muchane, Muchai; Naseri, Kamal; Pucheta, Eduardo; Ramírez-Collantes, David A; Raveh, Eran; Romão, Roberto L; Torres-Díaz, Cristian; Val, James; Veiga, José Pablo; Wang, Deli; Yuan, Xia; Zaady, Eli

2014-12-01

Geographic, climatic, and soil factors are major drivers of plant beta diversity, but their importance for dryland plant communities is poorly known. This study aims to: i) characterize patterns of beta diversity in global drylands, ii) detect common environmental drivers of beta diversity, and iii) test for thresholds in environmental conditions driving potential shifts in plant species composition. 224 sites in diverse dryland plant communities from 22 geographical regions in six continents. Beta diversity was quantified with four complementary measures: the percentage of singletons (species occurring at only one site), Whittake's beta diversity (β(W)), a directional beta diversity metric based on the correlation in species occurrences among spatially contiguous sites (β(R 2 )), and a multivariate abundance-based metric (β(MV)). We used linear modelling to quantify the relationships between these metrics of beta diversity and geographic, climatic, and soil variables. Soil fertility and variability in temperature and rainfall, and to a lesser extent latitude, were the most important environmental predictors of beta diversity. Metrics related to species identity (percentage of singletons and β(W)) were most sensitive to soil fertility, whereas those metrics related to environmental gradients and abundance ((β(R 2 )) and β(MV)) were more associated with climate variability. Interactions among soil variables, climatic factors, and plant cover were not important determinants of beta diversity. Sites receiving less than 178 mm of annual rainfall differed sharply in species composition from more mesic sites (> 200 mm). Soil fertility and variability in temperature and rainfall are the most important environmental predictors of variation in plant beta diversity in global drylands. Our results suggest that those sites annually receiving ~ 178 mm of rainfall will be especially sensitive to future climate changes. These findings may help to define appropriate conservation strategies for mitigating effects of climate change on dryland vegetation.

A spatial model for a stream networks of Citarik River with the environmental variables: potential of hydrogen (PH) and temperature

NASA Astrophysics Data System (ADS)

Bachrudin, A.; Mohamed, N. B.; Supian, S.; Sukono; Hidayat, Y.

2018-03-01

Application of existing geostatistical theory of stream networks provides a number of interesting and challenging problems. Most of statistical tools in the traditional geostatistics have been based on a Euclidean distance such as autocovariance functions, but for stream data is not permissible since it deals with a stream distance. To overcome this autocovariance developed a model based on the distance the flow with using convolution kernel approach (moving average construction). Spatial model for a stream networks is widely used to monitor environmental on a river networks. In a case study of a river in province of West Java, the objective of this paper is to analyze a capability of a predictive on two environmental variables, potential of hydrogen (PH) and temperature using ordinary kriging. Several the empirical results show: (1) The best fit of autocovariance functions for temperature and potential hydrogen (ph) of Citarik River is linear which also yields the smallest root mean squared prediction error (RMSPE), (2) the spatial correlation values between the locations on upstream and on downstream of Citarik river exhibit decreasingly

Reassessing the role of temperature in precipitation oxygen isotopes across the eastern and central United States through weekly precipitation-day data

NASA Astrophysics Data System (ADS)

Akers, Pete D.; Welker, Jeffrey M.; Brook, George A.

2017-09-01

Air temperature is correlated with precipitation oxygen isotope (δ18Oprcp) variability for much of the eastern and central United States, but the nature of this δ18Oprcp-temperature relationship is largely based on data coarsely aggregated at a monthly resolution. We constructed a database of 6177 weeks of isotope and precipitation-day air temperature data from 25 sites to determine how more precise data change our understanding of this classic relationship. Because the δ18Oprcp-temperature relationship is not perfectly linear, trends in the regression residuals suggest the influence of additional environmental factors such as moisture recycling and extratropical cyclone interactions. Additionally, the temporal relationships between δ18Oprcp and temperature observed in the weekly data at individual sites can explain broader spatial patterns observed across the study region. For 20 of 25 sites, the δ18Oprcp-temperature relationship slope is higher for colder precipitation than for warmer precipitation. Accordingly, northern and western sites with relatively more cold precipitation events have steeper overall relationships with higher slope values than southeastern sites that have more warm precipitation events. Although the magnitude of δ18Oprcp variability increases to the north and west, the fraction of δ18Oprcp variability explained by temperature increases due to wider annual temperature ranges, producing stronger relationships in these regions. When our δ18Oprcp-temperature data are grouped by month, we observe significant variations in the relationship from month to month. This argues against a principal causative role for temperature and suggests the existence of an alternative environmental control on δ18Oprcp values that simply covaries seasonally with temperature.

The effects of season and sand mining activities on thermal regime and water quality in a large shallow tropical lake.

PubMed

Sharip, Zati; Zaki, Ahmad Taqiyuddin Ahmad

2014-08-01

Thermal structure and water quality in a large and shallow lake in Malaysia were studied between January 2012 and June 2013 in order to understand variations in relation to water level fluctuations and in-stream mining activities. Environmental variables, namely temperature, turbidity, dissolved oxygen, pH, electrical conductivity, chlorophyll-A and transparency, were measured using a multi-parameter probe and a Secchi disk. Measurements of environmental variables were performed at 0.1 m intervals from the surface to the bottom of the lake during the dry and wet seasons. High water level and strong solar radiation increased temperature stratification. River discharges during the wet season, and unsustainable sand mining activities led to an increased turbidity exceeding 100 NTU, and reduced transparency, which changed the temperature variation and subsequently altered the water quality pattern.

Improving the use of environmental diversity as a surrogate for species representation.

PubMed

Albuquerque, Fabio; Beier, Paul

2018-01-01

The continuous p-median approach to environmental diversity (ED) is a reliable way to identify sites that efficiently represent species. A recently developed maximum dispersion (maxdisp) approach to ED is computationally simpler, does not require the user to reduce environmental space to two dimensions, and performed better than continuous p-median for datasets of South African animals. We tested whether maxdisp performs as well as continuous p-median for 12 datasets that included plants and other continents, and whether particular types of environmental variables produced consistently better models of ED. We selected 12 species inventories and atlases to span a broad range of taxa (plants, birds, mammals, reptiles, and amphibians), spatial extents, and resolutions. For each dataset, we used continuous p-median ED and maxdisp ED in combination with five sets of environmental variables (five combinations of temperature, precipitation, insolation, NDVI, and topographic variables) to select environmentally diverse sites. We used the species accumulation index (SAI) to evaluate the efficiency of ED in representing species for each approach and set of environmental variables. Maxdisp ED represented species better than continuous p-median ED in five of 12 biodiversity datasets, and about the same for the other seven biodiversity datasets. Efficiency of ED also varied with type of variables used to define environmental space, but no particular combination of variables consistently performed best. We conclude that maxdisp ED performs at least as well as continuous p-median ED, and has the advantage of faster and simpler computation. Surprisingly, using all 38 environmental variables was not consistently better than using subsets of variables, nor did any subset emerge as consistently best or worst; further work is needed to identify the best variables to define environmental space. Results can help ecologists and conservationists select sites for species representation and assist in conservation planning.

Probabilistic Thermal Analysis During Mars Reconnaissance Orbiter Aerobraking

NASA Technical Reports Server (NTRS)

Dec, John A.

2007-01-01

A method for performing a probabilistic thermal analysis during aerobraking has been developed. The analysis is performed on the Mars Reconnaissance Orbiter solar array during aerobraking. The methodology makes use of a response surface model derived from a more complex finite element thermal model of the solar array. The response surface is a quadratic equation which calculates the peak temperature for a given orbit drag pass at a specific location on the solar panel. Five different response surface equations are used, one of which predicts the overall maximum solar panel temperature, and the remaining four predict the temperatures of the solar panel thermal sensors. The variables used to define the response surface can be characterized as either environmental, material property, or modeling variables. Response surface variables are statistically varied in a Monte Carlo simulation. The Monte Carlo simulation produces mean temperatures and 3 sigma bounds as well as the probability of exceeding the designated flight allowable temperature for a given orbit. Response surface temperature predictions are compared with the Mars Reconnaissance Orbiter flight temperature data.

A Pathway-based Approach to Predicting Interactions between Chemical and Non-chemical Stressors: Applications to Global Climate Change

EPA Science Inventory

A variety of environmental variables influenced by global climate change (GCC) can directly or indirectly affect the health of organisms. These variables may include temperature, salinity, pH, and penetration of ultraviolet radiation (UVR) in aquatic environments, and water shor...

Environmental and Spatial Influences on Biogeography and Community Structure of Benthic Diatoms

NASA Astrophysics Data System (ADS)

Plante, C.; Hill-Spanik, K.; Lowry, J.

2016-02-01

Several theoretical and practical reasons suggest that benthic microalgae could be useful bioindicators. For instance, an ideal indicator species or community would be associated with a given habitat due to local physical conditions or biotic interactions (i.e., `environmental filtering'), not due to dispersal limitation. Due to their small size, immense abundances, and reliance on passive dispersal, the popular notion about micro-organisms is that `Everything is everywhere, but, the environment selects' (Baas-Becking 1934). Although much recent research concerning planktonic bacteria and dispersal limitation has been conducted, very little in this regard is known about microeukaryotes, especially benthic microbes. The purpose of our study was to identify and compare spatial and environmental influences on benthic diatom community structure and biogeography. In summer 2015, sediment was sampled at various spatial scales from four barrier island beaches in South Carolina, USA, and high-throughput (Ion Torrent) DNA sequencing was used to characterize diatom assemblages. ANOSIM and principal coordinates analysis revealed that communities were statistically distinct on the four islands. Community dissimilarity was compared to both spatial distance and environmental differences to determine potential influences of these variables on community structure. We found that geographic distance had the strongest correlation with community similarity, with and without one anomalous location, while differences in temperature (air, water, and sediment), nutrients, organic matter, and turbidity also had significant but weaker relationships with community structure. Surprisingly, air temperature, which changes on very short time scales, appeared to be the environmental factor most strongly related to diatom species composition, potentially implicating some unmeasured variable (e.g., cloud cover). However, we also found that temperature and geographic distance were strongly correlated. Future research will expand the spatial scope of this preliminary study and employ techniques (partial Mantel tests) to control for co-variation among variables.

An environmental tolerance index for ostracodes as indicators of physical and chemical factors in aquatic habitats

USGS Publications Warehouse

Curry, B. Brandon

1999-01-01

Continental ostracode occurrences reflect salinity, solute composition, temperature, flow conditions, and other environmental properties of the water they inhabit. Their occurrences also reflect the variability of many of these environmental parameters. Environmental tolerance indices (ETIs) offer a new way to express the nature of an ostracode's environment. As defined herein, ETIs range in value from zero to one, and may be calculated for continuous and binary variables. For continuous variables such as salinity, the ETI is the ratio of the range of values of salinity tolerated by an ostracode to the total range of salinity values from a representative database. In this investigation, the database of continuous variables consists of information from 341 sites located throughout the United States. Binary ETIs indicate whether an environmental variable such as flowing water affects ostracode presence or absence. The binary database consists of information from 784 sites primarily from Illinois, USA. ETIs were developed in this investigation to interpret paleohydrological changes implied by fossil ostracode successions. ETI profiles may be cast in terms of a weighted average, or on presence/absence. The profiles express ostracode tolerance of environmental parameters such as salinity or currents. Tolerance of a wide range of values is taken to indicate shallow water because shallow environments are conducive to thermal variability, short-term water residence, and the development of currents from wind-driven waves.

Neighbouring populations, opposite dynamics: influence of body size and environmental variation on the demography of stream-resident brown trout (Salmo trutta).

PubMed

Fernández-Chacón, Albert; Genovart, Meritxell; Álvarez, David; Cano, José M; Ojanguren, Alfredo F; Rodriguez-Muñoz, Rolando; Nicieza, Alfredo G

2015-06-01

In organisms such as fish, where body size is considered an important state variable for the study of their population dynamics, size-specific growth and survival rates can be influenced by local variation in both biotic and abiotic factors, but few studies have evaluated the complex relationships between environmental variability and size-dependent processes. We analysed a 6-year capture-recapture dataset of brown trout (Salmo trutta) collected at 3 neighbouring but heterogeneous mountain streams in northern Spain with the aim of investigating the factors shaping the dynamics of local populations. The influence of body size and water temperature on survival and individual growth was assessed under a multi-state modelling framework, an extension of classical capture-recapture models that considers the state (i.e. body size) of the individual in each capture occasion and allows us to obtain state-specific demographic rates and link them to continuous environmental variables. Individual survival and growth patterns varied over space and time, and evidence of size-dependent survival was found in all but the smallest stream. At this stream, the probability of reaching larger sizes was lower compared to the other wider and deeper streams. Water temperature variables performed better in the modelling of the highest-altitude population, explaining over a 99 % of the variability in maturation transitions and survival of large fish. The relationships between body size, temperature and fitness components found in this study highlight the utility of multi-state approaches to investigate small-scale demographic processes in heterogeneous environments, and to provide reliable ecological knowledge for management purposes.

ANALYSIS OF BIOTIC AND ABIOTIC FACTORS INFLUENCING THE OCCURRENCE OF WEST NILE VIRUS INFECTION IN TUNISIA.

PubMed

Ben Hassine, Th; Calistri, P; Ippoliti, C; Conte, A; Danzetta, M L; Bruno, R; Lelli, R; Bejaoui, M; Hammami, S

2014-01-01

Eco-climatic conditions are often associated with the occurrence of West Nile Disease (WND) cases. Among the complex set of biotic and abiotic factors influencing the emergence and spread of this vector-borne disease, two main variables have been considered to have a great influence on the probability of West Nile Virus (WNV) introduction and circulation in Tunisia: the presence of susceptible bird populations and the existence of geographical areas where the environmental and climatic conditions are more favourable to mosquito multiplications. The aim of this study was to identify and classify the climatic and environmental variables possibly associated with the occurrence of WNVhuman cases in Tunisia. The following environmental and climatic variables have been considered: wetlands and humid areas, Normalised Difference Vegetation Index (NDVI), temperatures and elevation. A preliminary analysis for the characterization of main variables associated with areas with a history of WNV human cases in Tunisia between 1997 and 2011 has been made. This preliminary analysis clearly indicates the closeness to marshes ecosystem, where migratory bird populations are located, as an important risk factor for WNV infection. On the contrary the temperature absolute seems to be not a significant factor in Tunisian epidemiological situation. In relation to NDVI values, more complex considerations should be made.

Predicting the unpredictable: potential climate change impacts on vegetation in the Pacific Northwest

Treesearch

Marie Oliver; David W. Peterson; Becky Kerns

2016-01-01

Earth's climate is changing, as evidenced by warming temperatures, increased temperature variability, fluctuating precipitation patterns, and climate-related environmental disturbances. And with considerable uncertainty about the future, Forest Service land managers are now considering climate change adaptation in their planning efforts. They want practical...

Relationship among environmental quality variables, housing variables, and residential needs: a secondary analysis of the relationship among indoor, outdoor, and personal air (RIOPA) concentrations database

NASA Astrophysics Data System (ADS)

Garcia, Fausto; Shendell, Derek G.; Madrigano, Jaime

2017-03-01

Retrospective descriptive secondary analyses of data from relationships of indoor, outdoor, and personal air (RIOPA) study homes (in Houston, Texas; Los Angeles County, California; and, Elizabeth, New Jersey May 1999-February 2001) were conducted. Data included air exchange rates, associations between indoor and outdoor temperature and humidity, and calculated apparent temperature and humidex. Analyses examined if study homes provided optimum thermal comfort for residents during both heating and cooling seasons when compared to current American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standards 62/62.1 and 55. Results suggested outdoor temperature, humidex, and apparent temperature during the cooling season potentially served as indicators of indoor personal exposure to parameters of thermal comfort. Outdoor temperatures, humidex, and apparent temperature during the cooling season had statistically significant predictive abilities in predicting indoor temperature. During the heating season, only humidex in Texas and combined data across study states were statistically significant, but with weaker to moderate predicative ability. The high degree of correlation between outdoor and indoor environmental variables provided support for the validity of epidemiologic studies of weather relying on temporal comparisons. Results indicated most RIOPA study residents experienced thermal comfort; however, many values indicated how several residents may have experienced some discomfort depending on clothing and indoor activities. With climate change, increases in temperature are expected, with more days of extreme heat and humidity and, potentially harsher, longer winters. Homes being built or modernized should be created with the appropriate guidelines to provide comfort for residents daily and in extreme weather events.

Relationship among environmental quality variables, housing variables, and residential needs: a secondary analysis of the relationship among indoor, outdoor, and personal air (RIOPA) concentrations database.

PubMed

Garcia, Fausto; Shendell, Derek G; Madrigano, Jaime

2017-03-01

Retrospective descriptive secondary analyses of data from relationships of indoor, outdoor, and personal air (RIOPA) study homes (in Houston, Texas; Los Angeles County, California; and, Elizabeth, New Jersey May 1999-February 2001) were conducted. Data included air exchange rates, associations between indoor and outdoor temperature and humidity, and calculated apparent temperature and humidex. Analyses examined if study homes provided optimum thermal comfort for residents during both heating and cooling seasons when compared to current American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standards 62/62.1 and 55. Results suggested outdoor temperature, humidex, and apparent temperature during the cooling season potentially served as indicators of indoor personal exposure to parameters of thermal comfort. Outdoor temperatures, humidex, and apparent temperature during the cooling season had statistically significant predictive abilities in predicting indoor temperature. During the heating season, only humidex in Texas and combined data across study states were statistically significant, but with weaker to moderate predicative ability. The high degree of correlation between outdoor and indoor environmental variables provided support for the validity of epidemiologic studies of weather relying on temporal comparisons. Results indicated most RIOPA study residents experienced thermal comfort; however, many values indicated how several residents may have experienced some discomfort depending on clothing and indoor activities. With climate change, increases in temperature are expected, with more days of extreme heat and humidity and, potentially harsher, longer winters. Homes being built or modernized should be created with the appropriate guidelines to provide comfort for residents daily and in extreme weather events.

Loggerhead sea turtle environmental sex determination: implications of moisture and temperature for climate change based predictions for species survival.

PubMed

Wyneken, Jeanette; Lolavar, Alexandra

2015-05-01

It has been proposed that because marine turtles have environmentally determined sex by incubation temperature, elevated temperatures might skew sex ratios to unsustainable levels, leading to extinction. Elevated temperatures may also reduce availability of suitable nesting sites via sea level rise. Increased tropical storm activity can directly affect nest site moisture, embryonic development, and the probability that nests will survive. Here, we question some of these assumptions and review the limits of sex ratio estimates. Sea turtles may be more resilient to climate change than previously thought, in part because of hitherto unappreciated mechanisms for coping with variable incubation conditions. © 2015 Wiley Periodicals, Inc.

Distribution of sea anemones (Cnidaria, Actiniaria) in Korea analyzed by environmental clustering

USGS Publications Warehouse

Cha, H.-R.; Buddemeier, R.W.; Fautin, D.G.; Sandhei, P.

2004-01-01

Using environmental data and the geospatial clustering tools LOICZView and DISCO, we empirically tested the postulated existence and boundaries of four biogeographic regions in the southern part of the Korean peninsula. Environmental variables used included wind speed, sea surface temperature (SST), salinity, tidal amplitude, and the chlorophyll spectral signal. Our analysis confirmed the existence of four biogeographic regions, but the details of the borders between them differ from those previously postulated. Specimen-level distribution records of intertidal sea anemones were mapped; their distribution relative to the environmental data supported the importance of the environmental parameters we selected in defining suitable habitats. From the geographic coincidence between anemone distribution and the clusters based on environmental variables, we infer that geospatial clustering has the power to delimit ranges for marine organisms within relatively small geographical areas.

Optimisation of contained Nicotiana tabacum cultivation for the production of recombinant protein pharmaceuticals.

PubMed

Colgan, Richard; Atkinson, Christopher J; Paul, Matthew; Hassan, Sally; Drake, Pascal M W; Sexton, Amy L; Santa-Cruz, Simon; James, David; Hamp, Keith; Gutteridge, Colin; Ma, Julian K-C

2010-04-01

Nicotiana tabacum is emerging as a crop of choice for production of recombinant protein pharmaceuticals. Although there is significant commercial expertise in tobacco farming, different cultivation practices are likely to be needed when the objective is to optimise protein expression, yield and extraction, rather than the traditional focus on biomass and alkaloid production. Moreover, pharmaceutical transgenic tobacco plants are likely to be grown initially within a controlled environment, the parameters for which have yet to be established. Here, the growth characteristics and functional recombinant protein yields for two separate transgenic tobacco plant lines were investigated. The impacts of temperature, day-length, compost nitrogen content, radiation and plant density were examined. Temperature was the only environmental variable to affect IgG concentration in the plants, with higher yields observed in plants grown at lower temperature. In contrast, temperature, supplementary radiation and plant density all affected the total soluble protein yield in the same plants. Transgenic plants expressing a second recombinant protein (cyanovirin-N) responded differently to IgG transgenic plants to elevated temperature, with an increase in cyanovirin-N concentration, although the effect of the environmental variables on total soluble protein yields was the same as the IgG plants. Planting density and radiation levels were important factors affecting variability of the two recombinant protein yields in transgenic plants. Phenotypic differences were observed between the two transgenic plant lines and non-transformed N. tabacum, but the effect of different growing conditions was consistent between the three lines. Temperature, day length, radiation intensity and planting density all had a significant impact on biomass production. Taken together, the data suggest that recombinant protein yield is not affected substantially by environmental factors other than growth temperature. Overall productivity is therefore correlated to biomass production, although other factors such as purification burden, extractability protein stability and quality also need to be considered in the optimal design of cultivation conditions.

Assessing the Habitat of Coccidioides posadasii, the Valley Fever Pathogen: A Study of Environmental Variables and Human Incidence Data in Arizona

NASA Astrophysics Data System (ADS)

Mann, Sarina N.

Coccidioidomycosis, or Valley Fever, is an infectious disease caused by inhalation of soil-dwelling fungus Coccidioides posadasii spores in the Lower Sonoran Life Zone (LSLZ) in Arizona. In the context of climate change, the habitat of environmentally-mediated infectious diseases, such as Valley Fever, are expected to change. Connections have been drawn between climate and Valley Fever infection. The operational scale of the organism is still unknown. Here, we use climatic variables, including precipitation, soil moisture, and temperature. We use PRISM precipitation and temperature data, and Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) as a measure of soil moisture for the entire state of Arizona, divided into 126 primary care areas (PCA). These data are analyzed and regressed with Valley Fever incidence to determine the effects of climatic variability on disease distribution and timing. This study confirms that Valley Fever occurrence is clustered in the LSLZ. Seasonal Valley Fever outbreak was found to be variable year-to-year based on climatic variability. The inconclusive regression analyses indicate that the operational scale of Coccidioides is smaller than the PCA region. All variables are related to Valley Fever infection, but one variable was not found to hold more predictive power than others.

Inter-annual dynamics of the Barents Sea red king crab (Paralithodes camtschaticus) stock indices in relation to environmental factors

NASA Astrophysics Data System (ADS)

Dvoretsky, Alexander G.; Dvoretsky, Vladimir G.

2016-12-01

Knowledge of relationships between environmental variables and biological processes can greatly improve fisheries assessment and management in commercially important species. We analyzed the effects of environmental factors (climatic indices and water temperature) on the stock characteristics (total population number, number of pre-recruits and number of legal males) of the red king crab (Paralithodes camtschaticus), an introduced species in the Barents Sea. Stock trends in red king crab appear to be related to decadal climate shifts. Abundances were negatively related to the North Atlantic Oscillation index (NAO) in August and positively related to water temperature in late winter-early summer. Total and commercial stock abundance were negatively correlated with the lag-1 Arctic Oscillation index (AO) in August and the lag-2 winter NAO index. The total number of P. camtschaticus was most strongly associated with water temperature in spring and summer and NAO/AO indices in April and May. Lagged NAO indices in February and August (9 or 10 yr) had a positive relationship to the commercial stock of P. camtschaticus. These findings suggest that temperature conditions of current and previous year affect natural mortality of larvae and juvenile red king crabs. Warmer temperature conditions lead to increased biomass of red king crab food items. Negative correlations between climatic indices and the red king crab stocks may be associated with predator pressure on juvenile red king crabs or higher mortality because of predator or parasite pressure and diseases. The associations between stock indices and environmental variables could help better predict recruitment patterns of P. camtschaticus.

Using NASA Remotely Sensed Data to Help Characterize Environmental Risk Factors for National Public Health Applications

NASA Technical Reports Server (NTRS)

Al-Hamdan, Mohammad; Crosson, William; Estes, Maury; Estes, Sue; Hemmings, Sarah; Quattrochi, Dale; McClure, Keslie; Kent, Shia; Economou, Sigrid; Puckett, Mark;

Relating large-scale climate variability to local species abundance: ENSO forcing and shrimp in Breton Sound, Louisiana, USA

USGS Publications Warehouse

Piazza, Bryan P.; LaPeyre, Megan K.; Keim, B.D.

2010-01-01

Climate creates environmental constraints (filters) that affect the abundance and distribution of species. In estuaries, these constraints often result from variability in water flow properties and environmental conditions (i.e. water flow, salinity, water temperature) and can have significant effects on the abundance and distribution of commercially important nekton species. We investigated links between large-scale climate variability and juvenile brown shrimp Farfantepenaeus aztecus abundance in Breton Sound estuary, Louisiana (USA). Our goals were to (1) determine if a teleconnection exists between local juvenile brown shrimp abundance and the El Niño Southern Oscillation (ENSO) and (2) relate that linkage to environmental constraints that may affect juvenile brown shrimp recruitment to, and survival in, the estuary. Our results identified a teleconnection between winter ENSO conditions and juvenile brown shrimp abundance in Breton Sound estuary the following spring. The physical connection results from the impact of ENSO on winter weather conditions in Breton Sound (air pressure, temperature, and precipitation). Juvenile brown shrimp abundance effects lagged ENSO by 3 mo: lower than average abundances of juvenile brown shrimp were caught in springs following winter El Niño events, and higher than average abundances of brown shrimp were caught in springs following La Niña winters. Salinity was the dominant ENSO-forced environmental filter for juvenile brown shrimp. Spring salinity was cumulatively forced by winter river discharge, winter wind forcing, and spring precipitation. Thus, predicting brown shrimp abundance requires incorporating climate variability into models.

GIS-based environmental analysis of fox and canine lungworm distribution: an epidemiological study of Angiostrongylus vasorum and Crenosoma vulpis in red foxes from Slovakia.

PubMed

Čabanová, Viktória; Miterpáková, Martina; Druga, Michal; Hurníková, Zuzana; Valentová, Daniela

2018-02-01

Over a period of intervening years, the distribution of two canine cardiopulmonary metastrongylid nematodes, Angiostrongylus vasorum and Crenosoma vulpis, has been recognised in Central Europe. Here, we report the first epidemiological research conducted in red foxes from Slovakia and the potential influence of selected environmental variables on the parasites' occurrence, quantified by logistic regression. The environmental models revealed that distribution of C. vulpis is not significantly influenced by any environmental variables, and the parasite is present in the whole area under study. Models for A. vasorum revealed some weak influence of environmental variables, as it tends to occur in drier areas with lower proportion of forest. Moreover, A. vasorum shows a typical spatial clustering and occurs in endemic foci identified mainly in the eastern part of Slovakia. A cluster of A. vasorum infection foci was also found in the north-eastern region, where the average winter air temperature regularly falls below - 10 °C.

Seasonal patterns of body temperature and microhabitat selection in a lacertid lizard

NASA Astrophysics Data System (ADS)

Ortega, Zaida; Pérez-Mellado, Valentín

2016-11-01

In temperate areas, seasonal changes entail a source of environmental variation potentially important for organisms. Temperate ectotherms may be adapted to the seasonal fluctuations in environmental traits. For lizards, behavioural adaptations regarding microhabitat selection could arise to improve thermoregulation during the different seasons. However, little is still known about which traits influence microhabitat selection of lizards and their adaptation to seasonality. Here we used Podarcis guadarramae to study the role of potential intrinsic (body size, sex, age) and environmental traits (air and substrate temperatures, wind speed, and sunlight) in the seasonal changes of body temperatures and microhabitat selection of lizards. We measured body temperatures of lizards in the same habitat during the four seasons and compared the climatic variables of the microhabitats selected by lizards with the mean climatic conditions available in their habitat. Body temperatures were similar for adult males, adult females, and juveniles within each season, being significantly higher in summer than in the other seasons, and in spring than in winter. The same pattern was found regarding substrate and air temperatures of the selected microhabitats. Wind speed and air temperature did not affect body temperatures, while body length was marginally significant and substrate temperatures and season did affect the body temperatures of lizards. Our results during the whole year support the idea that the seasonality could be the most important factor affecting body temperatures of these temperate species. Regarding microhabitat selection, environmental constraints, as environmental temperatures and wind speed, affected the seasonal changes on behavioural thermoregulation of lizards. This effect was similar between sexes and age classes, and was independent of body size. In addition, importance of sunlight exposure of the selected microhabitats (full sun, filtered sun, or shade) also changed between seasons. Hence, environmental constraints were the main forces driving seasonal changes in microhabitat selection.

The bivalve Glycymeris longior as an environmental archive for the Mar Argentino, southern South Atlantic

NASA Astrophysics Data System (ADS)

del Socorro Doldan, María; Morsan, Enrique Mario; Giménez, Lucas; Zaidman, Paula Cecilia

2017-04-01

Southern Hemisphere lacks of suitable high-resolution long datasets for the marine environment. This is translated in poor understanding of climate dynamics and processes at regional and continental-scale. We assessed the potential of Glycymeris longior as an environmental indicator for the mid-latitudes of South Atlantic by applying sclerochronological techniques on sample sets collected from San Matías Gulf, Mar Argentino, southern South Atlantic. We present a reconstruction of marine environmental variability of SMG for the period 1890-2016, covering 125 years. The reconstruction is based on the growth increment series for the first absolutely-dated annually-resolved multi-decadal G. longior bivalve on Sothern Atlantic. Shells were collected in 1918, 1933, 1945, 1983, 1989, 2009, 2011, 2015 and 2016. Sample depth varies between collection years. Age of the individuals was estimated from the hinge region of the shell. G. longior forms an annual narrow growth line. Maximal longevity was 40 years old. A strong common environmental signal is apparent in the increment widths. Correlations between the growth increment indices and regional temperature series (sea surface temperatures, continental temperatures) and other proxies were made. Preliminary results indicate that G.longior sclerochronologies, combined with low-frequency proxies can facilitate reconstructions of oceanographic variability. We discuss multi-decadal climate variability. Given the ability to generate annually-resolved chronologies G. longior is likely to be used as a climate recorder in southern South America. Hence, G. longior shells from Pleistocene marine deposits from Patagonia, Argentina, have a considerable potential to contain information of past climate for mid-latitudes of South Atlantic.

Environmental variables and levels of exhaled carbon monoxide and carboxyhemoglobin in elderly people taking exercise.

PubMed

Salicio, Marcos Adriano; Mana, Viviane Aparecida Martins; Fett, Waléria Christiane Rezende; Gomes, Luciano Teixeira; Botelho, Clovis

2016-04-01

This article aims to analyze levels of exhaled carbon monoxide, carboxyhemoglobinand cardiopulmonary variables in old people practicing exercise in external environments, and correlate them with climate and pollution factors. Temporal ecological study with118 active elderly people in the city of Cuiabá, in the state of Mato Grosso, Brazil. Data were obtained on use of medication, smoking, anthropometric measurements, spirometry, peak flow, oxygen saturation, heart rate, exhaled carbon monoxide, carboxyhemoglobin, climate, number of farm fires and pollution. Correlations were found between on the one hand environmental temperature, relative humidity of the air and number of farmers' fires, and on the other hand levels of carbon monoxide exhaled and carboxyhemoglobin (p < 0.05).There was a correlation between heart rate and changes in environmental temperature, time of exposure to the sun and relative humidity (p < 0.05). In elderly people, environmental factors influence levels of exhaled carbon monoxide, carboxyhemoglobin and heart rate. There is thus a need for these to be monitored during exercise. The use of a carbon monoxide monitor to evaluate exposure to pollutants is suggested.

Incorporating temporal heterogeneity in environmental conditions into a somatic growth model

USGS Publications Warehouse

Dzul, Maria C.; Yackulic, Charles B.; Korman, Josh; Yard, Michael D.; Muehlbauer, Jeffrey D.

2017-01-01

Evaluating environmental effects on fish growth can be challenging because environmental conditions may vary at relatively fine temporal scales compared to sampling occasions. Here we develop a Bayesian state-space growth model to evaluate effects of monthly environmental data on growth of fish that are observed less frequently (e.g., from mark-recapture data where time between captures can range from months to years). We assess effects of temperature, turbidity duration, food availability, flow variability, and trout abundance on subadult humpback chub (Gila cypha) growth in two rivers, the Colorado River (CR) and the Little Colorado River (LCR), and we use out-of-sample prediction to rank competing models. Environmental covariates explained a high proportion of the variation in growth in both rivers; however, the best growth models were river-specific and included either positive temperature and turbidity duration effects (CR) or positive temperature and food availability effects (LCR). Our approach to analyzing environmental controls on growth should be applicable in other systems where environmental data vary over relatively short time scales compared to animal observations.

Design of a WSN for the Sampling of Environmental Variability in Complex Terrain

PubMed Central

Martín-Tardío, Miguel A.; Felicísimo, Ángel M.

2014-01-01

In-situ environmental parameter measurements using sensor systems connected to a wireless network have become widespread, but the problem of monitoring large and mountainous areas by means of a wireless sensor network (WSN) is not well resolved. The main reasons for this are: (1) the environmental variability distribution is unknown in the field; (2) without this knowledge, a huge number of sensors would be necessary to ensure the complete coverage of the environmental variability and (3) WSN design requirements, for example, effective connectivity (intervisibility), limiting distances and controlled redundancy, are usually solved by trial and error. Using temperature as the target environmental variable, we propose: (1) a method to determine the homogeneous environmental classes to be sampled using the digital elevation model (DEM) and geometric simulations and (2) a procedure to determine an effective WSN design in complex terrain in terms of the number of sensors, redundancy, cost and spatial distribution. The proposed methodology, based on geographic information systems and binary integer programming can be easily adapted to a wide range of applications that need exhaustive and continuous environmental monitoring with high spatial resolution. The results show that the WSN design is perfectly suited to the topography and the technical specifications of the sensors, and provides a complete coverage of the environmental variability in terms of Sun exposure. However these results still need be validated in the field and the proposed procedure must be refined. PMID:25412218

Variable intertidal temperature explains why disease endangers black abalone

USGS Publications Warehouse

Ben-Horin, Tal; Lenihan, Hunter S.; Lafferty, Kevin D.

2013-01-01

Epidemiological theory suggests that pathogens will not cause host extinctions because agents of disease should fade out when the host population is driven below a threshold density. Nevertheless, infectious diseases have threatened species with extinction on local scales by maintaining high incidence and the ability to spread efficiently even as host populations decline. Intertidal black abalone (Haliotis cracherodii), but not other abalone species, went extinct locally throughout much of southern California following the emergence of a Rickettsiales-like pathogen in the mid-1980s. The rickettsial disease, a condition known as withering syndrome (WS), and associated mortality occur at elevated water temperatures. We measured abalone body temperatures in the field and experimentally manipulated intertidal environmental conditions in the laboratory, testing the influence of mean temperature and daily temperature variability on key epizootiological processes of WS. Daily temperature variability increased the susceptibility of black abalone to infection, but disease expression occurred only at warm water temperatures and was independent of temperature variability. These results imply that high thermal variation of the marine intertidal zone allows the pathogen to readily infect black abalone, but infected individuals remain asymptomatic until water temperatures periodically exceed thresholds modulating WS. Mass mortalities can therefore occur before pathogen transmission is limited by density-dependent factors.

Modelling the breeding of Aedes Albopictus species in an urban area in Pulau Pinang using polynomial regression

NASA Astrophysics Data System (ADS)

Salleh, Nur Hanim Mohd; Ali, Zalila; Noor, Norlida Mohd.; Baharum, Adam; Saad, Ahmad Ramli; Sulaiman, Husna Mahirah; Ahmad, Wan Muhamad Amir W.

2014-07-01

Polynomial regression is used to model a curvilinear relationship between a response variable and one or more predictor variables. It is a form of a least squares linear regression model that predicts a single response variable by decomposing the predictor variables into an nth order polynomial. In a curvilinear relationship, each curve has a number of extreme points equal to the highest order term in the polynomial. A quadratic model will have either a single maximum or minimum, whereas a cubic model has both a relative maximum and a minimum. This study used quadratic modeling techniques to analyze the effects of environmental factors: temperature, relative humidity, and rainfall distribution on the breeding of Aedes albopictus, a type of Aedes mosquito. Data were collected at an urban area in south-west Penang from September 2010 until January 2011. The results indicated that the breeding of Aedes albopictus in the urban area is influenced by all three environmental characteristics. The number of mosquito eggs is estimated to reach a maximum value at a medium temperature, a medium relative humidity and a high rainfall distribution.

Experimental evolution across different thermal regimes yields genetic divergence in recombination fraction but no divergence in temperature associated plastic recombination.

PubMed

Kohl, Kathryn P; Singh, Nadia D

2018-04-01

Phenotypic plasticity is pervasive in nature. One mechanism underlying the evolution and maintenance of such plasticity is environmental heterogeneity. Indeed, theory indicates that both spatial and temporal variation in the environment should favor the evolution of phenotypic plasticity under a variety of conditions. Cyclical environmental conditions have also been shown to yield evolved increases in recombination frequency. Here, we use a panel of replicated experimental evolution populations of D. melanogaster to test whether variable environments favor enhanced plasticity in recombination rate and/or increased recombination rate in response to temperature. In contrast to expectation, we find no evidence for either enhanced plasticity in recombination or increased rates of recombination in the variable environment lines. Our data confirm a role of temperature in mediating recombination fraction in D. melanogaster, and indicate that recombination is genetically and plastically depressed under lower temperatures. Our data further suggest that the genetic architectures underlying plastic recombination and population-level variation in recombination rate are likely to be distinct. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Comparison of the Effects of Environmental Parameters on the Growth Variability of Vibrio parahaemolyticus Coupled with Strain Sources and Genotypes Analyses.

PubMed

Liu, Bingxuan; Liu, Haiquan; Pan, Yingjie; Xie, Jing; Zhao, Yong

2016-01-01

Microbial growth variability plays an important role on food safety risk assessment. In this study, the growth kinetic characteristics corresponding to maximum specific growth rate (μmax) of 50 V. parahaemolyticus isolates from different sources and genotypes were evaluated at different temperatures (10, 20, 30, and 37°C) and salinity (0.5, 3, 5, 7, and 9%) using the automated turbidimetric system Bioscreen C. The results demonstrated that strain growth variability increased as the growth conditions became more stressful both in terms of temperature and salinity. The coefficient of variation (CV) of μmax for temperature was larger than that for salinity, indicating that the impact of temperature on strain growth variability was greater than that of salinity. The strains isolated from freshwater aquatic products had more conspicuous growth variations than those from seawater. Moreover, the strains with tlh (+) /tdh (+) /trh (-) exhibited higher growth variability than tlh (+) /tdh (-) /trh (-) or tlh (+) /tdh (-) /trh (+), revealing that gene heterogeneity might have possible relations with the growth variability. This research illustrates that the growth environments, strain sources as well as genotypes have impacts on strain growth variability of V. parahaemolyticus, which can be helpful for incorporating strain variability in predictive microbiology and microbial risk assessment.

Comparison of the Effects of Environmental Parameters on the Growth Variability of Vibrio parahaemolyticus Coupled with Strain Sources and Genotypes Analyses

PubMed Central

Liu, Bingxuan; Liu, Haiquan; Pan, Yingjie; Xie, Jing; Zhao, Yong

2016-01-01

Microbial growth variability plays an important role on food safety risk assessment. In this study, the growth kinetic characteristics corresponding to maximum specific growth rate (μmax) of 50 V. parahaemolyticus isolates from different sources and genotypes were evaluated at different temperatures (10, 20, 30, and 37°C) and salinity (0.5, 3, 5, 7, and 9%) using the automated turbidimetric system Bioscreen C. The results demonstrated that strain growth variability increased as the growth conditions became more stressful both in terms of temperature and salinity. The coefficient of variation (CV) of μmax for temperature was larger than that for salinity, indicating that the impact of temperature on strain growth variability was greater than that of salinity. The strains isolated from freshwater aquatic products had more conspicuous growth variations than those from seawater. Moreover, the strains with tlh+/tdh+/trh− exhibited higher growth variability than tlh+/tdh−/trh− or tlh+/tdh−/trh+, revealing that gene heterogeneity might have possible relations with the growth variability. This research illustrates that the growth environments, strain sources as well as genotypes have impacts on strain growth variability of V. parahaemolyticus, which can be helpful for incorporating strain variability in predictive microbiology and microbial risk assessment. PMID:27446034

Role of functionally dominant species in varying environmental regimes: evidence for the performance-enhancing effect of biodiversity.

PubMed

Langenheder, Silke; Bulling, Mark T; Prosser, James I; Solan, Martin

2012-07-30

Theory suggests that biodiversity can act as a buffer against disturbances and environmental variability via two major mechanisms: Firstly, a stabilising effect by decreasing the temporal variance in ecosystem functioning due to compensatory processes; and secondly, a performance enhancing effect by raising the level of community response through the selection of better performing species. Empirical evidence for the stabilizing effect of biodiversity is readily available, whereas experimental confirmation of the performance-enhancing effect of biodiversity is sparse. Here, we test the effect of different environmental regimes (constant versus fluctuating temperature) on bacterial biodiversity-ecosystem functioning relations. We show that positive effects of species richness on ecosystem functioning are enhanced by stronger temperature fluctuations due to the increased performance of individual species. Our results provide evidence for the performance enhancing effect and suggest that selection towards functionally dominant species is likely to benefit the maintenance of ecosystem functioning under more variable conditions.

Forecasting malaria incidence based on monthly case reports and environmental factors in Karuzi, Burundi, 1997–2003

PubMed Central

Gomez-Elipe, Alberto; Otero, Angel; van Herp, Michel; Aguirre-Jaime, Armando

2007-01-01

Background The objective of this work was to develop a model to predict malaria incidence in an area of unstable transmission by studying the association between environmental variables and disease dynamics. Methods The study was carried out in Karuzi, a province in the Burundi highlands, using time series of monthly notifications of malaria cases from local health facilities, data from rain and temperature records, and the normalized difference vegetation index (NDVI). Using autoregressive integrated moving average (ARIMA) methodology, a model showing the relation between monthly notifications of malaria cases and the environmental variables was developed. Results The best forecasting model (R2adj = 82%, p < 0.0001 and 93% forecasting accuracy in the range ± 4 cases per 100 inhabitants) included the NDVI, mean maximum temperature, rainfall and number of malaria cases in the preceding month. Conclusion This model is a simple and useful tool for producing reasonably reliable forecasts of the malaria incidence rate in the study area. PMID:17892540

Relationships between environmental conditions and the morphological variability of planktonic testate amoeba in four neotropical floodplains.

PubMed

Arrieira, Rodrigo Leite; Schwind, Leilane Talita Fatoreto; Joko, Ciro Yoshio; Alves, Geziele Mucio; Velho, Luiz Felipe Machado; Lansac-Tôha, Fábio Amodêo

2016-10-01

Planktonic testate amoebae in floodplains exhibit a broad-range of morphological variability. The variation size is already known, but it is necessary to know how this is for morphological variables. This study aimed to identify the relationships between testate amoebae morphology and environmental factors in four neotropical floodplains. We conducted detailed morphometric analyses on 27 common species of planktonic testate amoebae from genera Arcella, Centropyxis, Cucurbitella, Suiadifflugia, Difflugia, Lesquereusia and Netzelia. We sampled subsurface water from each lake in 72 lakes in four Brazilian floodplain lakes. Our goals were to assess: (1) the range of their morphological variability (a) over space within each floodplain, and (b) among the four floodplains, and (c) over time, and (2) which environmental factors explained this variation. Mean shell height and breadth varied considerably among the different floodplain lakes, especially in the Pantanal and Amazonian floodplains. The morphological variability of testate amoeba was correlated to environmental conditions (ammonia, nitrate, phosphate, chlorophyll-a, turbidity, temperature, and depth). Thus, understanding the morphological variation of the testate amoeba species can elucidate many questions involving the ecology of these organisms. Furthermore, could help molecular studies, bioindicator role of these organisations, environmental reconstruction, among others. Copyright © 2016 Elsevier GmbH. All rights reserved.

Climate and environmental change drives Ixodes ricinus geographical expansion at the northern range margin.

PubMed

Jore, Solveig; Vanwambeke, Sophie O; Viljugrein, Hildegunn; Isaksen, Ketil; Kristoffersen, Anja B; Woldehiwet, Zerai; Johansen, Bernt; Brun, Edgar; Brun-Hansen, Hege; Westermann, Sebastian; Larsen, Inger-Lise; Ytrehus, Bjørnar; Hofshagen, Merete

2014-01-08

Global environmental change is causing spatial and temporal shifts in the distribution of species and the associated diseases of humans, domesticated animals and wildlife. In the on-going debate on the influence of climate change on vectors and vector-borne diseases, there is a lack of a comprehensive interdisciplinary multi-factorial approach utilizing high quality spatial and temporal data. We explored biotic and abiotic factors associated with the latitudinal and altitudinal shifts in the distribution of Ixodes ricinus observed during the last three decades in Norway using antibodies against Anaplasma phagocytophilum in sheep as indicators for tick presence. Samples obtained from 2963 sheep from 90 farms in 3 ecologically different districts during 1978 - 2008 were analysed. We modelled the presence of antibodies against A. phagocytophilum to climatic-, environmental and demographic variables, and abundance of wild cervids and domestic animals, using mixed effect logistic regressions. Significant predictors were large diurnal fluctuations in ground surface temperature, spring precipitation, duration of snow cover, abundance of red deer and farm animals and bush encroachment/ecotones. The length of the growth season, mean temperature and the abundance of roe deer were not significant in the model. Our results highlight the need to consider climatic variables year-round to disentangle important seasonal variation, climatic threshold changes, climate variability and to consider the broader environmental change, including abiotic and biotic factors. The results offer novel insight in how tick and tick-borne disease distribution might be modified by future climate and environmental change.

Contemporary group estimates adjusted for climatic effects provide a finer definition of the unknown environmental challenges experienced by growing pigs.

PubMed

Guy, S Z Y; Li, L; Thomson, P C; Hermesch, S

2017-12-01

Environmental descriptors derived from mean performances of contemporary groups (CGs) are assumed to capture any known and unknown environmental challenges. The objective of this paper was to obtain a finer definition of the unknown challenges, by adjusting CG estimates for the known climatic effects of monthly maximum air temperature (MaxT), minimum air temperature (MinT) and monthly rainfall (Rain). As the unknown component could include infection challenges, these refined descriptors may help to better model varying responses of sire progeny to environmental infection challenges for the definition of disease resilience. Data were recorded from 1999 to 2013 at a piggery in south-east Queensland, Australia (n = 31,230). Firstly, CG estimates of average daily gain (ADG) and backfat (BF) were adjusted for MaxT, MinT and Rain, which were fitted as splines. In the models used to derive CG estimates for ADG, MaxT and MinT were significant variables. The models that contained these significant climatic variables had CG estimates with a lower variance compared to models without significant climatic variables. Variance component estimates were similar across all models, suggesting that these significant climatic variables accounted for some known environmental variation captured in CG estimates. No climatic variables were significant in the models used to derive the CG estimates for BF. These CG estimates were used to categorize environments. There was no observable sire by environment interaction (Sire×E) for ADG when using the environmental descriptors based on CG estimates on BF. For the environmental descriptors based on CG estimates of ADG, there was significant Sire×E only when MinT was included in the model (p = .01). Therefore, this new definition of the environment, preadjusted by MinT, increased the ability to detect Sire×E. While the unknown challenges captured in refined CG estimates need verification for infection challenges, this may provide a practical approach for the genetic improvement of disease resilience. © 2017 Blackwell Verlag GmbH.

Comparative Study of Drift Compensation Methods for Environmental Gas Sensors

NASA Astrophysics Data System (ADS)

Abidin, M. Z.; Asmat, Arnis; Hamidon, M. N.

2018-02-01

Most drift compensation attempts in environmental gas sensors are only emphasize on the “already-known” drift-causing parameter (i.e., ambient temperature, relative humidity) in compensating the sensor drift. Less consideration is taken to another parameter (i.e., baseline responses) that might have affected indirectly with the promotion of drift-causing parameter variable (in this context, is ambient temperature variable). In this study, the “indirect” drift-causing parameter (drifted baseline responses) has been taken into consideration in compensating the sensor drift caused by ambient temperature variable, by means of a proposed drift compensation method (named as RT-method). The effectiveness of this method in its efficacy of compensating drift was analysed and compared with the common method that used the “already-known” drift-causing parameter (named as T-method), using drift reduction percentage. From the results analysis, the RT-method has outperformed T- method in the drift reduction percentage, with its ability to reduce drift up to 64% rather than the T-method which only able to reduce up to 45% for TGS2600 sensor. It has proven that the inclusion of drifted baseline responses into drift compensation attempt would resulted to an improved drift compensation efficiency.

Testing the Effectiveness of Environmental Variables to Explain European Terrestrial Vertebrate Species Richness across Biogeographical Scales

PubMed Central

Mouchet, Maud; Levers, Christian; Zupan, Laure; Kuemmerle, Tobias; Plutzar, Christoph; Erb, Karlheinz; Lavorel, Sandra; Thuiller, Wilfried; Haberl, Helmut

2015-01-01

We compared the effectiveness of environmental variables, and in particular of land-use indicators, to explain species richness patterns across taxonomic groups and biogeographical scales (i.e. overall pan-Europe and ecoregions within pan-Europe). Using boosted regression trees that handle non-linear relationships, we compared the relative influence (as a measure of effectiveness) of environmental variables related to climate, landscape (or habitat heterogeneity), land-use intensity or energy availability to explain European vertebrate species richness (birds, amphibians, and mammals) at the continental and ecoregion scales. We found that dominant land cover and actual evapotranspiration that relate to energy availability were the main correlates of vertebrate species richness over Europe. At the ecoregion scale, we identified four distinct groups of ecoregions where species richness was essentially associated to (i) seasonality of temperature, (ii) actual evapotranspiration and/or mean annual temperature, (iii) seasonality of precipitation, actual evapotranspiration and land cover) and (iv) and an even combination of the environmental variables. This typology of ecoregions remained valid for total vertebrate richness and the three vertebrate groups taken separately. Despite the overwhelming influence of land cover and actual evapotranspiration to explain vertebrate species richness patterns at European scale, the ranking of the main correlates of species richness varied between regions. Interestingly, landscape and land-use indicators did not stand out at the continental scale but their influence greatly increased in southern ecoregions, revealing the long-lasting human footprint on land-use–land-cover changes. Our study provides one of the first multi-scale descriptions of the variability in the ranking of correlates across several taxa. PMID:26161981

The second Southern African Bird Atlas Project: Causes and consequences of geographical sampling bias.

PubMed

Hugo, Sanet; Altwegg, Res

2017-09-01

Using the Southern African Bird Atlas Project (SABAP2) as a case study, we examine the possible determinants of spatial bias in volunteer sampling effort and how well such biased data represent environmental gradients across the area covered by the atlas. For each province in South Africa, we used generalized linear mixed models to determine the combination of variables that explain spatial variation in sampling effort (number of visits per 5' × 5' grid cell, or "pentad"). The explanatory variables were distance to major road and exceptional birding locations or "sampling hubs," percentage cover of protected, urban, and cultivated area, and the climate variables mean annual precipitation, winter temperatures, and summer temperatures. Further, we used the climate variables and plant biomes to define subsets of pentads representing environmental zones across South Africa, Lesotho, and Swaziland. For each environmental zone, we quantified sampling intensity, and we assessed sampling completeness with species accumulation curves fitted to the asymptotic Lomolino model. Sampling effort was highest close to sampling hubs, major roads, urban areas, and protected areas. Cultivated area and the climate variables were less important. Further, environmental zones were not evenly represented by current data and the zones varied in the amount of sampling required representing the species that are present. SABAP2 volunteers' preferences in birding locations cause spatial bias in the dataset that should be taken into account when analyzing these data. Large parts of South Africa remain underrepresented, which may restrict the kind of ecological questions that may be addressed. However, sampling bias may be improved by directing volunteers toward undersampled regions while taking into account volunteer preferences.

Species composition of sand flies and bionomics of Phlebotomus papatasi and P. sergenti (Diptera: Psychodidae) in cutaneous leishmaniasis endemic foci, Morocco.

PubMed

Boussaa, Samia; Kahime, Kholoud; Samy, Abdallah M; Salem, Abdelkrim Ben; Boumezzough, Ali

2016-02-02

Cutaneous Leishmaniasis (CL) is one of the most neglected tropical diseases in Morocco. Leishmania major and L. tropica are the main culprits identified in all endemic foci across the country. These two etiological agents are transmitted by Phlebotomus papatasi and P. sergenti, the two most prevalent sand fly species in Morocco. Previous studies reflected gaps of knowledge regarding the environmental fingerprints that affect the distribution of these two potential vectors across Morocco. The sand flies were collected from 48 districts across Morocco using sticky paper traps. Collected specimens were preserved in 70% ethanol for further processing and identification. Male and female densities were calculated in each site to examine their relations to the environmental conditions across these sites. The study used 19 environmental variables including precipitation, aridity, elevation, soil variables and a composite representing maximum, minimum and mean of day- and night-time Land Surface Temperature (LST), and Normalized Difference Vegetation Index (NDVI). A total of 11,717 specimens were collected during this entomological survey. These specimens represented 11 species of two genera; Phlebotomus and Sergentomyia. Correlations of the sand fly densities with the environmental variables were estimated to identify the variables which influence the distribution of the two potential vectors, Phlebotomus papatasi and P. sergenti, associated with all CL endemic foci across the country. The density of P. papatasi was most affected by temperature changes. The study showed a significant positive correlation between the densities of both sexes of P. papatasi and night-time temperatures. Both P. papatasi and P. sergenti showed a negative correlation with aridity, but, such correlation was only significant in case of P. papatasi. NDVI showed a positive correlation only with densities of P. sergenti, while, soil PH and soil water stress were negatively correlated with the densities of both males and females of only P. papatasi. Our results identified the sand fly species across all CL endemic sites and underlined the influences of night-time temperature, soil water stress and NDVI as the most important variables affecting the sand fly distribution in all sampled sites. This preliminary study considered the importance of these covariates to anticipate the potential distribution of P. papatasi and P. sergenti in Morocco.

Spatio-temporal analysis of preterm birth in Portugal and its relation with environmental variables

NASA Astrophysics Data System (ADS)

Oliveira, M.; Teodoro, Ana C.; Freitas, A.; Bernardes, J.; Gonçalves, H.

2016-10-01

Preterm birth (PTB), one of the major concerns in obstetrics, is conventionally defined as the delivery of a live infant before 37 completed weeks of gestation, and one of its causes may be environmental factors. Remote sensing is a valuable approach for monitoring environmental variables, including in health sciences. In this work, remote sensing data were used to explore the relation of the environment with PTB. Time-series with monthly rates of male/female ratio and PTB were obtained from Portugal in 2000-2014. The environmental variables included in this study were monthly mean temperatures (T), relative humidity (RH), NDVI, concentrations of NO2 and PM10 in 2003-2008. A temporal and spatial analysis of each health-related and environmental variable was performed, as well as their correlation. PTB has been increasing over time, from below 5% in 2000 to around 7% in 2014, with predominance of higher rates in districts with larger population. From 2003 to 2008, T and PM10 decreased significantly. A positive and significant correlation was found between male/female ratio and NO2 and RH, and to a lesser extent with PM10 and NDVI. PTB was also positively and significantly correlated with NO2 and T, and to a lesser extent with RH and PM10. These preliminary results suggest an association of PTB with most of the environmental variables studied, showing that more polluted and populated districts have higher rates of PTB. Further studies are warranted to explore interaction between the considered environmental factors and other variables related with risk for PTB.

Computer analysis of environmental temperature, light and noise in intensive care: chaos or chronome nurseries?

PubMed

Ardura, J; Andrés, J; Aldana, J; Revilla, M A; Cornélissen, G; Halberg, F

1997-09-01

Lighting, noise and temperature were monitored in two perinatal nurseries. Rhythms of several frequencies were found, including prominent 24-hour rhythms with acrophases around 13:00 (light intensity) and 16:00 (noise). For light and noise, the ratio formed by dividing the amplitude of a 1-week (circaseptan) or half-week (circasemiseptan) fitted cosine curve by the amplitude of a 24-hour fitted cosine curve is smaller than unity, since 24-hour rhythms are prominent for these variables. The amplitude ratios are larger than unity for temperature in the newborns' unit but not in the infants' unit. Earlier, the origin of the about-7-day rhythms of neonatal physiologic variables was demonstrated to have, in addition to a major endogenous, also a minor exogenous component. Hence, the possibility of optimizing maturation by manipulating environmental changes can be considered, using, as gauges of development, previously mapped chronomes (time structures of biologic multifrequency rhythms, trends and noise).

Factors influencing spatial variability in nitrogen processing in nitrogen-saturated soils

Treesearch

Frank S. Gilliam; Charles C. Somerville; Nikki L. Lyttle; Mary Beth Adams

2001-01-01

Nitrogen (N) saturation is an environmental concern for forests in the eastern U.S. Although several watersheds of the Fernow Experimental Forest (FEF), West Virginia exhibit symptoms of N saturation, many watersheds display a high degree of spatial variability in soil N processing. This study examined the effects of temperature on net N mineralization and...

Climate and soil attributes determine plant species turnover in global drylands

PubMed Central

Maestre, Fernando T.; Gotelli, Nicholas J.; Quero, José L.; Delgado-Baquerizo, Manuel; Bowker, Matthew A.; Eldridge, David J.; Ochoa, Victoria; Gozalo, Beatriz; Valencia, Enrique; Berdugo, Miguel; Escolar, Cristina; García-Gómez, Miguel; Escudero, Adrián; Prina, Aníbal; Alfonso, Graciela; Arredondo, Tulio; Bran, Donaldo; Cabrera, Omar; Cea, Alex; Chaieb, Mohamed; Contreras, Jorge; Derak, Mchich; Espinosa, Carlos I.; Florentino, Adriana; Gaitán, Juan; Muro, Victoria García; Ghiloufi, Wahida; Gómez-González, Susana; Gutiérrez, Julio R.; Hernández, Rosa M.; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Mau, Rebecca L.; Hughes, Frederic Mendes; Miriti, Maria; Monerris, Jorge; Muchane, Muchai; Naseri, Kamal; Pucheta, Eduardo; Ramírez-Collantes, David A.; Raveh, Eran; Romão, Roberto L.; Torres-Díaz, Cristian; Val, James; Veiga, José Pablo; Wang, Deli; Yuan, Xia; Zaady, Eli

2015-01-01

Aim Geographic, climatic, and soil factors are major drivers of plant beta diversity, but their importance for dryland plant communities is poorly known. This study aims to: i) characterize patterns of beta diversity in global drylands, ii) detect common environmental drivers of beta diversity, and iii) test for thresholds in environmental conditions driving potential shifts in plant species composition. Location 224 sites in diverse dryland plant communities from 22 geographical regions in six continents. Methods Beta diversity was quantified with four complementary measures: the percentage of singletons (species occurring at only one site), Whittake’s beta diversity (β(W)), a directional beta diversity metric based on the correlation in species occurrences among spatially contiguous sites (β(R2)), and a multivariate abundance-based metric (β(MV)). We used linear modelling to quantify the relationships between these metrics of beta diversity and geographic, climatic, and soil variables. Results Soil fertility and variability in temperature and rainfall, and to a lesser extent latitude, were the most important environmental predictors of beta diversity. Metrics related to species identity (percentage of singletons and β(W)) were most sensitive to soil fertility, whereas those metrics related to environmental gradients and abundance ((β(R2)) and β(MV)) were more associated with climate variability. Interactions among soil variables, climatic factors, and plant cover were not important determinants of beta diversity. Sites receiving less than 178 mm of annual rainfall differed sharply in species composition from more mesic sites (> 200 mm). Main conclusions Soil fertility and variability in temperature and rainfall are the most important environmental predictors of variation in plant beta diversity in global drylands. Our results suggest that those sites annually receiving ~ 178 mm of rainfall will be especially sensitive to future climate changes. These findings may help to define appropriate conservation strategies for mitigating effects of climate change on dryland vegetation. PMID:25914437

Environmental factors associated with long-term changes in chlorophyll concentration in the Sacramento-San Joaquin delta and Suisun Bay, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehman, P.W.

Long-term changes in chlorophyll concentration were predicted from environmental variables using Box-Jenkins transfer function models for the Sacramento and San Joaquin rivers and Suisun Bay. The indication that oceanic phytoplankton biomass for the California regions is associated with climatic phenomena produced by El Nino and the Southern Oscillation (ENSO) was one of several factors used to standardize the dataset. Data used for the analyses were collected continuously on a semimonthly or monthly basis over the 17-yr period between 1971 and 1987. Groups of highly correlated environmental variables were summarized along three environmental axes using principal component analysis. The first environmentalmore » axis summarized river flow and specific conductance. The second environmental axis summarized water transparency and the third environmental axis summarized air and water temperature. Chlorophyll concentration was significantly cross-correlated with environmental axes and individual environmental variables. Transfer function models developed to describe changes in chlorophyll concentration over time were characterized by lag responses and described between 41% and 51% of the data variation. Significant cross-correlations between environmental axes and the California climate index (CA SLP) were used to develop a conceptual model of the link between regional climate and estuarine production. 50 refs., 5 figs.« less

Environmental forcing on jellyfish communities in a small temperate estuary.

PubMed

Primo, Ana Lígia; Marques, Sónia C; Falcão, Joana; Crespo, Daniel; Pardal, Miguel A; Azeiteiro, Ulisses M

2012-08-01

The impact of biological, hydrodynamic and large scale climatic variables on the jellyfish community of Mondego estuary was evaluated from 2003 to 2010. Plankton samples were collected at the downstream part of the estuary. Siphonophora Muggiaea atlantica and Diphyes spp. were the main jellyfish species. Jellyfish density was generally higher in summer and since 2005 densities had increased. Summer community analysis pointed out Acartia clausi, estuarine temperature and salinity as the main driven forces for the assemblage's structure. Also, Chl a, estuarine salinity, runoff and SST were identified as the major environmental factors influencing the siphonophores summer interannual variability. Temperature influenced directly and indirectly the community and fluctuation of jellyfish blooms in the Mondego estuary. This study represents a contribution to a better knowledge of the gelatinous plankton communities in small temperate estuaries. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Temperature Sensitivity (Q10) of Soil Respiration: Controlling Factors and Spatial Prediction at Regional Scale Based on Environmental Soil Classes

NASA Astrophysics Data System (ADS)

Meyer, N.; Welp, G.; Amelung, W.

2018-02-01

The temperature sensitivity of heterotrophic soil respiration is crucial for modeling carbon dynamics but it is variable. Presently, however, most models employ a fixed value of 1.5 or 2.0 for the increase of soil respiration per 10°C increase in temperature (Q10). Here we identified the variability of Q10 at a regional scale (Rur catchment, Germany/Belgium/Netherlands). We divided the study catchment into environmental soil classes (ESCs), which we define as unique combinations of land use, aggregated soil groups, and texture. We took nine soil samples from each ESC (108 samples) and incubated them at four soil moisture levels and five temperatures (5-25°C). We hypothesized that Q10 variability is controlled by soil organic carbon (SOC) degradability and soil moisture and that ESC can be used as a widely available proxy for Q10, owing to differences in SOC degradability. Measured Q10 values ranged from 1.2 to 2.8 and were correlated with indicators of SOC degradability (e.g., pH, r = -0.52). The effect of soil moisture on Q10 was variable: Q10 increased with moisture in croplands but decreased in forests. The ESC captured significant parts of Q10 variability under dry (R2 = 0.44) and intermediate (R2 = 0.36) moisture conditions, where Q10 increased in the order cropland

Spatially-Resolved Influence of Temperature and Salinity on Stock and Recruitment Variability of Commercially Important Fishes in the North Sea

PubMed Central

Akimova, Anna; Núñez-Riboni, Ismael; Kempf, Alexander; Taylor, Marc H.

2016-01-01

Understanding of the processes affecting recruitment of commercially important fish species is one of the major challenges in fisheries science. Towards this aim, we investigated the relation between North Sea hydrography (temperature and salinity) and fish stock variables (recruitment, spawning stock biomass and pre-recruitment survival index) for 9 commercially important fishes using spatially-resolved cross-correlation analysis. We used high-resolution (0.2° × 0.2°) hydrographic data fields matching the maximal temporal extent of the fish population assessments (1948–2013). Our approach allowed for the identification of regions in the North Sea where environmental variables seem to be more influential on the fish stocks, as well as the regions of a lesser or nil influence. Our results confirmed previously demonstrated negative correlations between temperature and recruitment of cod and plaice and identified regions of the strongest correlations (German Bight for plaice and north-western North Sea for cod). We also revealed a positive correlation between herring spawning stock biomass and temperature in the Orkney-Shetland area, as well as a negative correlation between sole pre-recruitment survival index and temperature in the German Bight. A strong positive correlation between sprat stock variables and salinity in the central North Sea was also found. To our knowledge the results concerning correlations between North Sea hydrography and stocks’ dynamics of herring, sole and sprat are novel. The new information about spatial distribution of the correlation provides an additional help to identify mechanisms underlying these correlations. As an illustration of the utility of these results for fishery management, an example is provided that incorporates the identified environmental covariates in stock-recruitment models. PMID:27584155

Responses of plant growth and metabolism to environmental variables predicted from laboratory measurements

Treesearch

Lee D. Hansen; Bruce N. Smith; Richard S. Criddle; J. N. Church

2001-01-01

The Arrhenius activation energies, and therefore temperature coefficients, for rates of catabolic production of ATP and for anabolic use of ATP differ. Because the intracellular concentration of ATP and the phosphorylation potential must be controlled within a narrow range for cell survival, a mechanism must exist to balance these rates during temperature variation in...

Elevated surface temperature depresses survival of banner-tailed kangaroo rats: will climate change cook a desert icon?

PubMed

Moses, Martin R; Frey, Jennifer K; Roemer, Gary W

2012-01-01

Modest increases in global temperature have been implicated in causing population extirpations and range shifts in taxa inhabiting colder environs and in ectotherms whose thermoregulation is more closely tied to environmental conditions. Many arid-adapted endotherms already experience conditions at their physiological limits, so it is conceivable that they could be similarly affected by warming temperatures. We explored how climatic variables might influence the apparent survival of the banner-tailed kangaroo rat (Dipodomys spectabilis), a rodent endemic to the Chihuahuan Desert of North America and renowned for its behavioral and physiological adaptations to arid environments. Relative variable weight, strength of variable relationships, and other criteria indicated that summer, diurnal land surface temperature (SD_LST) was the primary environmental driver of apparent survival in these arid-adapted rodents. Higher temperatures had a negative effect on apparent survival, which ranged from 0.15 (SE = 0.04) for subadults to 0.50 (SE = 0.07) for adults. Elevated SD_LST may negatively influence survival through multiple pathways, including increased water loss and energy expenditure that could lead to chronic stress and/or hyperthermia that could cause direct mortality. Land surface temperatures are predicted to increase by as much 6.5°C by 2099, reducing apparent survival of adults to ~0.15 in some regions of the species' range, possibly causing a shift in their distribution. The relationship between SD_LST and survival suggests a mechanism whereby physiological tolerances are exceeded resulting in a reduction to individual fitness that may ultimately cause a shift in the species' range over time.

Environmental Variability in the Florida Keys: Impacts on Coral Reef Resilience and Health

NASA Astrophysics Data System (ADS)

Soto, I. M.; Muller-Karger, F. E.

2005-12-01

Environmental variability contributes to both mass mortality and resilience in tropical coral reef communities. We assess variations in sea surface temperature (SST) and ocean color in the Florida Keys using satellite imagery, and provide insight into how this variability is associated with locations of resilient coral communities (those unaffected by or able to recover from major events). The project tests the hypothesis that areas with historically low environmental variability promote lower levels of coral reef resilience. Time series of SST from the Advanced Very High Resolution Radiometer (AVHRR) sensors and ocean color derived quantities (e.g., turbidity and chlorophyll) from the Sea-viewing Wide Field of View Sensor (SeaWiFS) are being constructed over the entire Florida Keys region for a period of twelve and nine years, respectively. These data will be compared with historical coral cover data derived from Landsat imagery (1984-2002). Improved understanding of the causes of coral reef decline or resilience will help protect and manage these natural treasures.

An Alexandrium Spp. Cyst Record from Sequim Bay, Washington State, USA, and its Relation to Past Climate Variability(1).

PubMed

Feifel, Kirsten M; Moore, Stephanie K; Horner, Rita A

2012-06-01

Since the 1970s, Puget Sound, Washington State, USA, has experienced an increase in detections of paralytic shellfish toxins (PSTs) in shellfish due to blooms of the harmful dinoflagellate Alexandrium. Natural patterns of climate variability, such as the Pacific Decadal Oscillation (PDO), and changes in local environmental factors, such as sea surface temperature (SST) and air temperature, have been linked to the observed increase in PSTs. However, the lack of observations of PSTs in shellfish prior to the 1950s has inhibited statistical assessments of longer-term trends in climate and environmental conditions on Alexandrium blooms. After a bloom, Alexandrium cells can enter a dormant cyst stage, which settles on the seafloor and then becomes entrained into the sedimentary record. In this study, we created a record of Alexandrium spp. cysts from a sediment core obtained from Sequim Bay, Puget Sound. Cyst abundances ranged from 0 to 400 cysts · cm(-3) and were detected down-core to a depth of 100 cm, indicating that Alexandrium has been present in Sequim Bay since at least the late 1800s. The cyst record allowed us to statistically examine relationships with available environmental parameters over the past century. Local air temperature and sea surface temperature were positively and significantly correlated with cyst abundances from the late 1800s to 2005; no significant relationship was found between PDO and cyst abundances. This finding suggests that local environmental variations more strongly influence Alexandrium population dynamics in Puget Sound when compared to large-scale changes. © 2012 Phycological Society of America.

A panel study in congestive heart failure to estimate the short-term effects from personal factors and environmental conditions on oxygen saturation and pulse rate.

PubMed

Goldberg, M S; Giannetti, N; Burnett, R T; Mayo, N E; Valois, M-F; Brophy, J M

2008-10-01

Recent studies suggest that persons with congestive heart failure (CHF) may be at higher risk for short-term effects of air pollution. This daily diary panel study in Montreal, Quebec, was carried out to determine whether oxygen saturation and pulse rate were associated with selected personal factors, weather conditions and air pollution. Thirty-one subjects with CHF participated in this study in 2002 and 2003. Over a 2-month period, the investigators measured their oxygen saturation, pulse rate, weight and temperature each morning and recorded these and other data in a daily diary. Air pollution and weather conditions were obtained from fixed-site monitoring stations. The study made use of mixed regression models, adjusting for within-subject serial correlation and temporal trends, to determine the association between oxygen saturation and pulse rate and personal and environmental variables. Depending on the model, we accounted for the effects of a variety of personal variables (eg, body temperature, salt consumption) as well as nitrogen dioxide (NO2), ozone, maximum temperature and change in barometric pressure at 8:00 from the previous day. In multivariable analyses, the study found that oxygen saturation was reduced when subjects reported that they were ill, consumed salt, or drank liquids on the previous day and had higher body temperatures on the concurrent day (only the latter was statistically significant). Relative humidity and decreased atmospheric pressure from the previous day were associated with oxygen saturation. In univariate analyses, there was negative associations with concentrations of fine particulates, ozone, and sulphur dioxide (SO2), but only SO2 was significant after adjustment for the effects of weather. For pulse rate, no associations were found for the personal variables and in univariate analyses the study found positive associations with NO(2), fine particulates (aerodynamic diameter of 2.5 microm or under, PM(2.5)), SO2, and maximum temperature, although only the latter two were significant after adjustment for environmental effects. The findings from the present investigation suggest that personal and environmental conditions affect intermediate physiological parameters that may affect the health of CHF patients.

Temperature and relative humidity estimation and prediction in the tobacco drying process using Artificial Neural Networks.

PubMed

Martínez-Martínez, Víctor; Baladrón, Carlos; Gomez-Gil, Jaime; Ruiz-Ruiz, Gonzalo; Navas-Gracia, Luis M; Aguiar, Javier M; Carro, Belén

2012-10-17

This paper presents a system based on an Artificial Neural Network (ANN) for estimating and predicting environmental variables related to tobacco drying processes. This system has been validated with temperature and relative humidity data obtained from a real tobacco dryer with a Wireless Sensor Network (WSN). A fitting ANN was used to estimate temperature and relative humidity in different locations inside the tobacco dryer and to predict them with different time horizons. An error under 2% can be achieved when estimating temperature as a function of temperature and relative humidity in other locations. Moreover, an error around 1.5 times lower than that obtained with an interpolation method can be achieved when predicting the temperature inside the tobacco mass as a function of its present and past values with time horizons over 150 minutes. These results show that the tobacco drying process can be improved taking into account the predicted future value of the monitored variables and the estimated actual value of other variables using a fitting ANN as proposed.

Temperature and Relative Humidity Estimation and Prediction in the Tobacco Drying Process Using Artificial Neural Networks

PubMed Central

Martínez-Martínez, Víctor; Baladrón, Carlos; Gomez-Gil, Jaime; Ruiz-Ruiz, Gonzalo; Navas-Gracia, Luis M.; Aguiar, Javier M.; Carro, Belén

2012-01-01

This paper presents a system based on an Artificial Neural Network (ANN) for estimating and predicting environmental variables related to tobacco drying processes. This system has been validated with temperature and relative humidity data obtained from a real tobacco dryer with a Wireless Sensor Network (WSN). A fitting ANN was used to estimate temperature and relative humidity in different locations inside the tobacco dryer and to predict them with different time horizons. An error under 2% can be achieved when estimating temperature as a function of temperature and relative humidity in other locations. Moreover, an error around 1.5 times lower than that obtained with an interpolation method can be achieved when predicting the temperature inside the tobacco mass as a function of its present and past values with time horizons over 150 minutes. These results show that the tobacco drying process can be improved taking into account the predicted future value of the monitored variables and the estimated actual value of other variables using a fitting ANN as proposed. PMID:23202032

Influence of environmental variables on diffusive greenhouse gas fluxes at hydroelectric reservoirs in Brazil.

PubMed

Rogério, J P; Santos, M A; Santos, E O

2013-11-01

For almost two decades, studies have been under way in Brazil, showing how hydroelectric reservoirs produce biogenic gases, mainly methane (CH4) and carbon dioxide (CO2), through the organic decomposition of flooded biomass. This somewhat complex phenomenon is due to a set of variables with differing levels of interdependence that directly or indirectly affect greenhouse gas (GHG) emissions. The purpose of this paper is to determine, through a statistical data analysis, the relation between CO2, CH4 diffusive fluxes and environmental variables at the Furnas, Itumbiara and Serra da Mesa hydroelectric reservoirs, located in the Cerrado biome on Brazil's high central plateau. The choice of this region was prompted by its importance in the national context, covering an area of some two million square kilometers, encompassing two major river basins (Paraná and Tocantins-Araguaia), with the largest installed power generation capacity in Brazil, together accounting for around 23% of Brazilian territory. This study shows that CH4 presented a moderate negative correlation between CO2 and depth. Additionally, a moderate positive correlation was noted for pH, water temperature and wind. The CO2 presented a moderate negative correlation for pH, wind speed, water temperature and air temperature. Additionally, a moderate positive correlation was noted for CO2 and water temperature. The complexity of the emission phenomenon is unlikely to occur through a simultaneous understanding of all the factors, due to difficulties in accessing and analyzing all the variables that have real, direct effects on GHG production and emission.

[Spatio-temporal analysis of the biophysical and ecological conditions of Triatoma dimidiata (Hemiptera: Reduviidae: Triatominae) in the northeast region of Colombia].

PubMed

Badel-Mogollón, Jaime; Rodríguez-Figueroa, Laura; Parra-Henao, Gabriel

2017-03-29

Due to the lack of information regarding biophysical and spatio-temporal conditions (hydrometheorologic and vegetal coverage density) in areas with Triatoma dimidiata in the Colombian departments of Santander and Boyacá, there is a need to elucidate the association patterns of these variables to determine the distribution and control of this species. To make a spatio-temporal analysis of biophysical variables related to the distribution of T. dimidiate observed in the northeast region of Colombia. We used the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) data bases registering vector presence and hydrometheorologic data. We studied the variables of environmental temperature, relative humidity, rainfall and vegetal coverage density at regional and local levels, and we conducted spatial geostatistic, descriptive statistical and Fourier temporal series analyses. Temperatures two meters above the ground and on covered surface ranged from 14,5°C to 18,8°C in the areas with the higher density of T. dimidiata. The environmental temperature fluctuated between 30 and 32°C. Vegetal coverage density and rainfall showed patterns of annual and biannual peaks. Relative humidity values fluctuated from 66,8 to 85,1%. Surface temperature and soil coverage were the variables that better explained the life cycle of T. dimidiata in the area. High relative humidity promoted the seek of shelters and an increase of the geographic distribution in the annual and biannual peaks of regional rainfall. The ecologic and anthropic conditions suggest that T. dimidiata is a highly resilient species.

Environmental factors affecting feed intake of steers in different housing systems in the summer

NASA Astrophysics Data System (ADS)

Koknaroglu, H.; Otles, Z.; Mader, T.; Hoffman, M. P.

2008-07-01

A total of 188 yearling steers of predominantly Angus and Hereford breeds, with mean body weight of 299 kg, were used in this study, which started on 8 April and finished on 3 October, to assess the effects of environmental factors on feed intake of steers in various housing systems. Housing consisted of outside lots with access to overhead shelter, outside lots with no overhead shelter and a cold confinement building. Ad libitum corn, 2.27 kg of 35% dry matter whole plant sorghum silage and 0.68 kg of a 61% protein-vitamin-mineral supplement was offered. Feed that was not consumed was measured to determine feed intake. The temperature data were recorded by hygro-thermographs. Hourly temperatures and humidity were used to develop weather variables. Regression analysis was used and weather variables were regressed on dry matter intake (DMI). When addition of a new variable did not improve R 2 more than one unit, then the number of variables in the model was truncated. Cattle in confinement had lower DMI than those in open lots and those in open lots with access to an overhead shelter ( P < 0.05). Cattle in outside lots with access to overhead shelter had similar DMI compared to those in open lots ( P = 0.065). Effect of heat was predominantly displayed in August in the three housing systems. In terms of explaining variation in DMI, in outside lots with access to overhead shelter, average and daytime temperatures were important factors, whereas in open lots, nocturnal, peak and average temperatures were important factors. In confinement buildings, the previous day’s temperature and humidity index were the most important factors explaining variation in DMI. Results show the effect of housing and weather variables on DMI in summer and when considering these results, cattle producers wishing to improve cattle feedlot performance should consider housing conditions providing less stress or more comfort.

Interannual, seasonal and diurnal Mars surface environmental cycles observed from Viking to Curiosity

NASA Astrophysics Data System (ADS)

Martinez, German; Vicente-Retortillo, Álvaro; Kemppinen, Osku; Fischer, Erik; Fairen, Alberto G.; Guzewich, Scott David; Haberle, Robert; Lemmon, Mark T.; Newman, Claire E.; Renno, Nilton O.; Richardson, Mark I.; Smith, Michael D.; De la Torre, Manuel; Vasavada, Ashwin R.

2016-10-01

We analyze in-situ environmental data from the Viking landers to the Curiosity rover to estimate atmospheric pressure, near-surface air and ground temperature, relative humidity, wind speed and dust opacity with the highest confidence possible. We study the interannual, seasonal and diurnal variability of these quantities at the various landing sites over a span of more than twenty Martian years to characterize the climate on Mars and its variability. Additionally, we characterize the radiative environment at the various landing sites by estimating the daily UV irradiation (also called insolation and defined as the total amount of solar UV energy received on flat surface during one sol) and by analyzing its interannual and seasonal variability.In this study we use measurements conducted by the Viking Meteorology Instrument System (VMIS) and Viking lander camera onboard the Viking landers (VL); the Atmospheric Structure Instrument/Meteorology (ASIMET) package and the Imager for Mars Pathfinder (IMP) onboard the Mars Pathfinder (MPF) lander; the Miniature Thermal Emission Spectrometer (Mini-TES) and Pancam instruments onboard the Mars Exploration Rovers (MER); the Meteorological Station (MET), Thermal Electrical Conductivity Probe (TECP) and Phoenix Surface Stereo Imager (SSI) onboard the Phoenix (PHX) lander; and the Rover Environmental Monitoring Station (REMS) and Mastcam instrument onboard the Mars Science Laboratory (MSL) rover.A thorough analysis of in-situ environmental data from past and present missions is important to aid in the selection of the Mars 2020 landing site. We plan to extend our analysis of Mars surface environmental cycles by using upcoming data from the Temperature and Wind sensors (TWINS) instrument onboard the InSight mission and the Mars Environmental Dynamics Analyzer (MEDA) instrument onboard the Mars 2020 mission.

Variable cycle engines for advanced supersonic transports

NASA Technical Reports Server (NTRS)

Howlett, R. A.; Kozlowski, H.

1975-01-01

Variable Cycle Engines being studied for advanced commercial supersonic transports show potential for significant environmental and economic improvements relative to 1st generation SST engines. The two most promising concepts are: a Variable Stream Control Engine and a Variable Cycle Engine with a rear flow-control valve. Each concept utilizes variable components and separate burners to provide independent temperature and velocity control for two coannular flow streams. Unique fuel control techniques are combined with cycle characteristics that provide low fuel consumption, similar to a turbojet engine, for supersonic operation. This is accomplished while retaining the good subsonic performance features of a turbofan engine. A two-stream coannular nozzle shows potential to reduce jet noise to below FAR Part 36 without suppressors. Advanced burner concepts have the potential for significant reductions in exhaust emissions. In total, these unique engine concepts have the potential for significant overall improvements to the environmental and economic characteristics of advanced supersonic transports.

Impacts of Climate Trends and Variability on Livestock Production in Brazil

NASA Astrophysics Data System (ADS)

Cohn, A.; Munger, J.; Gibbs, H.

2015-12-01

Cattle systems of Brazil are of major economic and environmental importance. They occupy ¼ of the land surface of the country, account for over 15 billion USD of annual revenue through the sale of beef, leather, and milk, are closely associated with deforestation, and have been projected to substantially grow in the coming decades. Sustainable intensification of production in the sector could help to limit environmental harm from increased production, but productivity growth could be inhibited by climate change. Gauging the potential future impacts of climate change on the Brazilian livestock sector can be aided by examining past evidence of the link between climate and cattle production and productivity. We use statistical techniques to investigate the contribution of climate variability and climate change to variability in cattle system output in Brazil's municipalities over the period 1974 to 2013. We find significant impacts of both temperature and precipitation variability and temperature trends on municipality-level exports and the production of both milk and beef. Pasture productivity, represented by a vegetation index, also varies significantly with climate shocks. In some regions, losses from exposure to climate trends were of comparable magnitude to technology and/or market-driven productivity gains over the study period.

Environmental Predictors of Diversity in Recent Planktonic Foraminifera as Recorded in Marine Sediments

PubMed Central

Pearson, Paul N.; Dunkley Jones, Tom; Purvis, Andy

2016-01-01

Global diversity patterns are thought to result from a combination of environmental and historical factors. This study tests the set of ecological and evolutionary hypotheses proposed to explain the global variation in present-day coretop diversity in the macroperforate planktonic foraminifera, a clade with an exceptional fossil record. Within this group, marine surface sediment assemblages are thought to represent an accurate, although centennial to millennial time-averaged, representation of recent diversity patterns. Environmental variables chosen to capture ocean temperature, structure, productivity and seasonality were used to model a range of diversity measures across the world’s oceans. Spatial autoregressive models showed that the same broad suite of environmental variables were important in shaping each of the four largely independent diversity measures (rarefied species richness, Simpson’s evenness, functional richness and mean evolutionary age). Sea-surface temperature explains the largest portion of diversity in all four diversity measures, but not in the way predicted by the metabolic theory of ecology. Vertical structure could be linked to increased diversity through the strength of stratification, but not through the depth of the mixed layer. There is limited evidence that seasonal turnover explains diversity patterns. There is evidence for functional redundancy in the low-latitude sites. The evolutionary mechanism of deep-time stability finds mixed support whilst there is relatively little evidence for an out-of-the-tropics model. These results suggest the diversity patterns of planktonic foraminifera cannot be explained by any one environmental variable or proposed mechanism, but instead reflect multiple processes acting in concert. PMID:27851751

Environmental Predictors of Diversity in Recent Planktonic Foraminifera as Recorded in Marine Sediments.

PubMed

Fenton, Isabel S; Pearson, Paul N; Dunkley Jones, Tom; Purvis, Andy

2016-01-01

Global diversity patterns are thought to result from a combination of environmental and historical factors. This study tests the set of ecological and evolutionary hypotheses proposed to explain the global variation in present-day coretop diversity in the macroperforate planktonic foraminifera, a clade with an exceptional fossil record. Within this group, marine surface sediment assemblages are thought to represent an accurate, although centennial to millennial time-averaged, representation of recent diversity patterns. Environmental variables chosen to capture ocean temperature, structure, productivity and seasonality were used to model a range of diversity measures across the world's oceans. Spatial autoregressive models showed that the same broad suite of environmental variables were important in shaping each of the four largely independent diversity measures (rarefied species richness, Simpson's evenness, functional richness and mean evolutionary age). Sea-surface temperature explains the largest portion of diversity in all four diversity measures, but not in the way predicted by the metabolic theory of ecology. Vertical structure could be linked to increased diversity through the strength of stratification, but not through the depth of the mixed layer. There is limited evidence that seasonal turnover explains diversity patterns. There is evidence for functional redundancy in the low-latitude sites. The evolutionary mechanism of deep-time stability finds mixed support whilst there is relatively little evidence for an out-of-the-tropics model. These results suggest the diversity patterns of planktonic foraminifera cannot be explained by any one environmental variable or proposed mechanism, but instead reflect multiple processes acting in concert.

Modelling spatio-temporal variability of Mytilus edulis (L.) growth by forcing a dynamic energy budget model with satellite-derived environmental data

NASA Astrophysics Data System (ADS)

Thomas, Yoann; Mazurié, Joseph; Alunno-Bruscia, Marianne; Bacher, Cédric; Bouget, Jean-François; Gohin, Francis; Pouvreau, Stéphane; Struski, Caroline

2011-11-01

In order to assess the potential of various marine ecosystems for shellfish aquaculture and to evaluate their carrying capacities, there is a need to clarify the response of exploited species to environmental variations using robust ecophysiological models and available environmental data. For a large range of applications and comparison purposes, a non-specific approach based on 'generic' individual growth models offers many advantages. In this context, we simulated the response of blue mussel ( Mytilus edulis L.) to the spatio-temporal fluctuations of the environment in Mont Saint-Michel Bay (North Brittany) by forcing a generic growth model based on Dynamic Energy Budgets with satellite-derived environmental data (i.e. temperature and food). After a calibration step based on data from mussel growth surveys, the model was applied over nine years on a large area covering the entire bay. These simulations provide an evaluation of the spatio-temporal variability in mussel growth and also show the ability of the DEB model to integrate satellite-derived data and to predict spatial and temporal growth variability of mussels. Observed seasonal, inter-annual and spatial growth variations are well simulated. The large-scale application highlights the strong link between food and mussel growth. The methodology described in this study may be considered as a suitable approach to account for environmental effects (food and temperature variations) on physiological responses (growth and reproduction) of filter feeders in varying environments. Such physiological responses may then be useful for evaluating the suitability of coastal ecosystems for shellfish aquaculture.

Climate and environmental change drives Ixodes ricinus geographical expansion at the northern range margin

PubMed Central

2014-01-01

Background Global environmental change is causing spatial and temporal shifts in the distribution of species and the associated diseases of humans, domesticated animals and wildlife. In the on-going debate on the influence of climate change on vectors and vector-borne diseases, there is a lack of a comprehensive interdisciplinary multi-factorial approach utilizing high quality spatial and temporal data. Methods We explored biotic and abiotic factors associated with the latitudinal and altitudinal shifts in the distribution of Ixodes ricinus observed during the last three decades in Norway using antibodies against Anaplasma phagocytophilum in sheep as indicators for tick presence. Samples obtained from 2963 sheep from 90 farms in 3 ecologically different districts during 1978 – 2008 were analysed. We modelled the presence of antibodies against A. phagocytophilum to climatic-, environmental and demographic variables, and abundance of wild cervids and domestic animals, using mixed effect logistic regressions. Results Significant predictors were large diurnal fluctuations in ground surface temperature, spring precipitation, duration of snow cover, abundance of red deer and farm animals and bush encroachment/ecotones. The length of the growth season, mean temperature and the abundance of roe deer were not significant in the model. Conclusions Our results highlight the need to consider climatic variables year-round to disentangle important seasonal variation, climatic threshold changes, climate variability and to consider the broader environmental change, including abiotic and biotic factors. The results offer novel insight in how tick and tick-borne disease distribution might be modified by future climate and environmental change. PMID:24401487

Lowering Temperature is the Trigger for Glycogen Build-Up and Winter Fasting in Crucian Carp (Carassius carassius).

PubMed

Varis, Joonas; Haverinen, Jaakko; Vornanen, Matti

2016-02-01

Seasonal changes in physiology of vertebrate animals are triggered by environmental cues including temperature, day-length and oxygen availability. Crucian carp (Carassius carassius) tolerate prolonged anoxia in winter by using several physiological adaptations that are seasonally activated. This study examines which environmental cues are required to trigger physiological adjustments for winter dormancy in crucian carp. To this end, crucian carp were exposed to changing environmental factors under laboratory conditions: effects of declining water temperature, shortening day-length and reduced oxygen availability, separately and in different combinations, were examined on glycogen content and enzyme activities involved in feeding (alkaline phosphatase, AP) and glycogen metabolism (glycogen synthase, GyS; glycogen phosphorylase, GP). Lowering temperature induced a fall in activity of AP and a rise in glycogen content and rate of glycogen synthesis. Relative mass of the liver, and glycogen concentration of liver, muscle and brain increased with lowering temperature. Similarly activity of GyS in muscle and expression of GyS transcripts in brain were up-regulated by lowering temperature. Shortened day-length and oxygen availability had practically no effects on measured variables. We conclude that lowering temperature is the main trigger in preparation for winter anoxia in crucian carp.

The evolution of phenotypic plasticity in fish swimming

PubMed Central

Oufiero, Christopher E.; Whitlow, Katrina R.

2016-01-01

Abstract Fish have a remarkable amount of variation in their swimming performance, from within species differences to diversity among major taxonomic groups. Fish swimming is a complex, integrative phenotype and has the ability to plastically respond to a myriad of environmental changes. The plasticity of fish swimming has been observed on whole-organismal traits such as burst speed or critical swimming speed, as well as underlying phenotypes such as muscle fiber types, kinematics, cardiovascular system, and neuronal processes. Whether the plastic responses of fish swimming are beneficial seems to depend on the environmental variable that is changing. For example, because of the effects of temperature on biochemical processes, alterations of fish swimming in response to temperature do not seem to be beneficial. In contrast, changes in fish swimming in response to variation in flow may benefit the fish to maintain position in the water column. In this paper, we examine how this plasticity in fish swimming might evolve, focusing on environmental variables that have received the most attention: temperature, habitat, dissolved oxygen, and carbon dioxide variation. Using examples from previous research, we highlight many of the ways fish swimming can plastically respond to environmental variation and discuss potential avenues of future research aimed at understanding how plasticity of fish swimming might evolve. We consider the direct and indirect effects of environmental variation on swimming performance, including changes in swimming kinematics and suborganismal traits thought to predict swimming performance. We also discuss the role of the evolution of plasticity in shaping macroevolutionary patterns of diversity in fish swimming. PMID:29491937

Inter-Annual Variability of the Acoustic Propagation in the Mediterranean Sea Identified from a Synoptic Monthly Gridded Database as Compared with GDEM

DTIC Science & Technology

2016-12-01

VARIABILITY OF THE ACOUSTIC PROPAGATION IN THE MEDITERRANEAN SEA IDENTIFIED FROM A SYNOPTIC MONTHLY GRIDDED DATABASE AS COMPARED WITH GDEM by...ANNUAL VARIABILITY OF THE ACOUSTIC PROPAGATION IN THE MEDITERRANEAN SEA IDENTIFIED FROM A SYNOPTIC MONTHLY GRIDDED DATABASE AS COMPARED WITH GDEM 5...profiles obtained from the synoptic monthly gridded World Ocean Database (SMD-WOD) and Generalized Digital Environmental Model (GDEM) temperature (T

Evolutionary potential of upper thermal tolerance: biogeographic patterns and expectations under climate change.

PubMed

Diamond, Sarah E

2017-02-01

How will organisms respond to climate change? The rapid changes in global climate are expected to impose strong directional selection on fitness-related traits. A major open question then is the potential for adaptive evolutionary change under these shifting climates. At the most basic level, evolutionary change requires the presence of heritable variation and natural selection. Because organismal tolerances of high temperature place an upper bound on responding to temperature change, there has been a surge of research effort on the evolutionary potential of upper thermal tolerance traits. Here, I review the available evidence on heritable variation in upper thermal tolerance traits, adopting a biogeographic perspective to understand how heritability of tolerance varies across space. Specifically, I use meta-analytical models to explore the relationship between upper thermal tolerance heritability and environmental variability in temperature. I also explore how variation in the methods used to obtain these thermal tolerance heritabilities influences the estimation of heritable variation in tolerance. I conclude by discussing the implications of a positive relationship between thermal tolerance heritability and environmental variability in temperature and how this might influence responses to future changes in climate. © 2016 New York Academy of Sciences.

Cold Regions Environmental Considerations

DTIC Science & Technology

2009-02-03

braided streams, variable discharge, seasonal breakup) limited seasonally limited abundant Hydrology (frozen lakes and bogs) not present seasonally...fuel hoses may crack increasing the potential for fuel spills. Extreme care must be used when handling cables at cold temperatures, protecting the

Modelling the effects of environmental conditions on the acoustic occurrence and behaviour of Antarctic blue whales

PubMed Central

Shabangu, Fannie W.; Yemane, Dawit; Stafford, Kathleen M.; Ensor, Paul; Findlay, Ken P.

2017-01-01

Harvested to perilously low numbers by commercial whaling during the past century, the large scale response of Antarctic blue whales Balaenoptera musculus intermedia to environmental variability is poorly understood. This study uses acoustic data collected from 586 sonobuoys deployed in the austral summers of 1997 through 2009, south of 38°S, coupled with visual observations of blue whales during the IWC SOWER line-transect surveys. The characteristic Z-call and D-call of Antarctic blue whales were detected using an automated detection template and visual verification method. Using a random forest model, we showed the environmental preferences pattern, spatial occurrence and acoustic behaviour of Antarctic blue whales. Distance to the southern boundary of the Antarctic Circumpolar Current (SBACC), latitude and distance from the nearest Antarctic shores were the main geographic predictors of blue whale call occurrence. Satellite-derived sea surface height, sea surface temperature, and productivity (chlorophyll-a) were the most important environmental predictors of blue whale call occurrence. Call rates of D-calls were strongly predicted by the location of the SBACC, latitude and visually detected number of whales in an area while call rates of Z-call were predicted by the SBACC, latitude and longitude. Satellite-derived sea surface height, wind stress, wind direction, water depth, sea surface temperatures, chlorophyll-a and wind speed were important environmental predictors of blue whale call rates in the Southern Ocean. Blue whale call occurrence and call rates varied significantly in response to inter-annual and long term variability of those environmental predictors. Our results identify the response of Antarctic blue whales to inter-annual variability in environmental conditions and highlighted potential suitable habitats for this population. Such emerging knowledge about the acoustic behaviour, environmental and habitat preferences of Antarctic blue whales is important in improving the management and conservation of this highly depleted species. PMID:28222124

Modelling the effects of environmental conditions on the acoustic occurrence and behaviour of Antarctic blue whales.

PubMed

Shabangu, Fannie W; Yemane, Dawit; Stafford, Kathleen M; Ensor, Paul; Findlay, Ken P

2017-01-01

Harvested to perilously low numbers by commercial whaling during the past century, the large scale response of Antarctic blue whales Balaenoptera musculus intermedia to environmental variability is poorly understood. This study uses acoustic data collected from 586 sonobuoys deployed in the austral summers of 1997 through 2009, south of 38°S, coupled with visual observations of blue whales during the IWC SOWER line-transect surveys. The characteristic Z-call and D-call of Antarctic blue whales were detected using an automated detection template and visual verification method. Using a random forest model, we showed the environmental preferences pattern, spatial occurrence and acoustic behaviour of Antarctic blue whales. Distance to the southern boundary of the Antarctic Circumpolar Current (SBACC), latitude and distance from the nearest Antarctic shores were the main geographic predictors of blue whale call occurrence. Satellite-derived sea surface height, sea surface temperature, and productivity (chlorophyll-a) were the most important environmental predictors of blue whale call occurrence. Call rates of D-calls were strongly predicted by the location of the SBACC, latitude and visually detected number of whales in an area while call rates of Z-call were predicted by the SBACC, latitude and longitude. Satellite-derived sea surface height, wind stress, wind direction, water depth, sea surface temperatures, chlorophyll-a and wind speed were important environmental predictors of blue whale call rates in the Southern Ocean. Blue whale call occurrence and call rates varied significantly in response to inter-annual and long term variability of those environmental predictors. Our results identify the response of Antarctic blue whales to inter-annual variability in environmental conditions and highlighted potential suitable habitats for this population. Such emerging knowledge about the acoustic behaviour, environmental and habitat preferences of Antarctic blue whales is important in improving the management and conservation of this highly depleted species.

Predictions of avian Plasmodium expansion under climate change.

PubMed

Loiseau, Claire; Harrigan, Ryan J; Bichet, Coraline; Julliard, Romain; Garnier, Stéphane; Lendvai, Adám Z; Chastel, Olivier; Sorci, Gabriele

2013-01-01

Vector-borne diseases are particularly responsive to changing environmental conditions. Diurnal temperature variation has been identified as a particularly important factor for the development of malaria parasites within vectors. Here, we conducted a survey across France, screening populations of the house sparrow (Passer domesticus) for malaria (Plasmodium relictum). We investigated whether variation in remotely-sensed environmental variables accounted for the spatial variation observed in prevalence and parasitemia. While prevalence was highly correlated to diurnal temperature range and other measures of temperature variation, environmental conditions could not predict spatial variation in parasitemia. Based on our empirical data, we mapped malaria distribution under climate change scenarios and predicted that Plasmodium occurrence will spread to regions in northern France, and that prevalence levels are likely to increase in locations where transmission already occurs. Our findings, based on remote sensing tools coupled with empirical data suggest that climatic change will significantly alter transmission of malaria parasites.

Photosynthetic parameters in the Beaufort Sea in relation to the phytoplankton community structure

NASA Astrophysics Data System (ADS)

Huot, Y.; Babin, M.; Bruyant, F.

2013-05-01

To model phytoplankton primary production from remotely sensed data, a method to estimate photosynthetic parameters describing the photosynthetic rates per unit biomass is required. Variability in these parameters must be related to environmental variables that are measurable remotely. In the Arctic, a limited number of measurements of photosynthetic parameters have been carried out with the concurrent environmental variables needed. Such measurements and their relationship to environmental variables will be required to improve the accuracy of remotely sensed estimates of phytoplankton primary production and our ability to predict future changes. During the MALINA cruise, a large dataset of these parameters was obtained. Together with previously published datasets, we use environmental and trophic variables to provide functional relationships for these parameters. In particular, we describe several specific aspects: the maximum rate of photosynthesis (Pmaxchl) normalized to chlorophyll decreases with depth and is higher for communities composed of large cells; the saturation parameter (Ek) decreases with depth but is independent of the community structure; and the initial slope of the photosynthesis versus irradiance curve (αchl) normalized to chlorophyll is independent of depth but is higher for communities composed of larger cells. The photosynthetic parameters were not influenced by temperature over the range encountered during the cruise (-2 to 8 °C).

Photosynthetic parameters in the Beaufort Sea in relation to the phytoplankton community structure

NASA Astrophysics Data System (ADS)

Huot, Y.; Babin, M.; Bruyant, F.

2013-01-01

To model phytoplankton primary production from remotely sensed data a method to estimate photosynthetic parameters describing the photosynthetic rates per unit biomass is required. Variability in these parameters must be related to environmental variables that are measurable remotely. In the Arctic, a limited number of measurements of photosynthetic parameter have been carried out with the concurrent environmental variables needed. Therefore, to improve the accuracy of remote estimates of phytoplankton primary production as well as our ability to predict changes in the future such measurements and relationship to environmental variables are required. During the MALINA cruise, a large dataset of these parameters were obtained. Together with previously published datasets, we use environmental and trophic variables to provide functional relationships for these parameters. In particular, we describe several specific aspects: the maximum rate of photosynthesis (Pmaxchl) normalized to chlorophyll decreases with depth and is higher for communities composed of large cells; the saturation parameter (Ek) decreases with depth but is independent of the community structure; and the initial slope of the photosynthesis versus irradiance curve (αchl) normalized to chlorophyll is independent of depth but is higher for communities composed of larger cells. The photosynthetic parameters were not influenced by temperature over the range encountered during the cruise (-2 to 8 °C).

High Performance CMOS Light Detector with Dark Current Suppression in Variable-Temperature Systems.

PubMed

Lin, Wen-Sheng; Sung, Guo-Ming; Lin, Jyun-Long

2016-12-23

This paper presents a dark current suppression technique for a light detector in a variable-temperature system. The light detector architecture comprises a photodiode for sensing the ambient light, a dark current diode for conducting dark current suppression, and a current subtractor that is embedded in the current amplifier with enhanced dark current cancellation. The measured dark current of the proposed light detector is lower than that of the epichlorohydrin photoresistor or cadmium sulphide photoresistor. This is advantageous in variable-temperature systems, especially for those with many infrared light-emitting diodes. Experimental results indicate that the maximum dark current of the proposed current amplifier is approximately 135 nA at 125 °C, a near zero dark current is achieved at temperatures lower than 50 °C, and dark current and temperature exhibit an exponential relation at temperatures higher than 50 °C. The dark current of the proposed light detector is lower than 9.23 nA and the linearity is approximately 1.15 μA/lux at an external resistance R SS = 10 kΩ and environmental temperatures from 25 °C to 85 °C.

High Performance CMOS Light Detector with Dark Current Suppression in Variable-Temperature Systems

PubMed Central

Lin, Wen-Sheng; Sung, Guo-Ming; Lin, Jyun-Long

2016-01-01

This paper presents a dark current suppression technique for a light detector in a variable-temperature system. The light detector architecture comprises a photodiode for sensing the ambient light, a dark current diode for conducting dark current suppression, and a current subtractor that is embedded in the current amplifier with enhanced dark current cancellation. The measured dark current of the proposed light detector is lower than that of the epichlorohydrin photoresistor or cadmium sulphide photoresistor. This is advantageous in variable-temperature systems, especially for those with many infrared light-emitting diodes. Experimental results indicate that the maximum dark current of the proposed current amplifier is approximately 135 nA at 125 °C, a near zero dark current is achieved at temperatures lower than 50 °C, and dark current and temperature exhibit an exponential relation at temperatures higher than 50 °C. The dark current of the proposed light detector is lower than 9.23 nA and the linearity is approximately 1.15 μA/lux at an external resistance RSS = 10 kΩ and environmental temperatures from 25 °C to 85 °C. PMID:28025530

Heterogeneous Multi-Robot System for Mapping Environmental Variables of Greenhouses

PubMed Central

Roldán, Juan Jesús; Garcia-Aunon, Pablo; Garzón, Mario; de León, Jorge; del Cerro, Jaime; Barrientos, Antonio

2016-01-01

The productivity of greenhouses highly depends on the environmental conditions of crops, such as temperature and humidity. The control and monitoring might need large sensor networks, and as a consequence, mobile sensory systems might be a more suitable solution. This paper describes the application of a heterogeneous robot team to monitor environmental variables of greenhouses. The multi-robot system includes both ground and aerial vehicles, looking to provide flexibility and improve performance. The multi-robot sensory system measures the temperature, humidity, luminosity and carbon dioxide concentration in the ground and at different heights. Nevertheless, these measurements can be complemented with other ones (e.g., the concentration of various gases or images of crops) without a considerable effort. Additionally, this work addresses some relevant challenges of multi-robot sensory systems, such as the mission planning and task allocation, the guidance, navigation and control of robots in greenhouses and the coordination among ground and aerial vehicles. This work has an eminently practical approach, and therefore, the system has been extensively tested both in simulations and field experiments. PMID:27376297

Relationship between the fungal complex causing Fusarium head blight of wheat and environmental conditions.

PubMed

Xu, X-M; Nicholson, P; Thomsett, M A; Simpson, D; Cooke, B M; Doohan, F M; Brennan, J; Monaghan, S; Moretti, A; Mule, G; Hornok, L; Beki, E; Tatnell, J; Ritieni, A; Edwards, S G

2008-01-01

ABSTRACT Over 4 years, the environmental conditions and the causal agents of Fusarium head blight (FHB) disease of wheat were determined in field sites in four European countries: Hungary, Ireland, Italy, and the United Kingdom. Polymerase chain reaction-based methods were used to detect each species causing FHB and quantify its DNA (as a measurement of fungal abundance) in the samples. Canonical correspondence analysis (CCA) was used to determine the relationship of the incidence and abundance of each species with weather variables. CCA indicated that little variability in the species prevalence data was explained by the weather variables. In contrast, a greater proportion of variability in abundance data was accounted for by the weather variables. Most samples contained two or more species and statistical analysis suggested that these species tended to coexist at field sites. CCA also indicated that there were differences in the relationships of the prevalence and abundance of the six FHB species with environmental variables. Fusarium poae was associated with relatively drier and warmer conditions, whereas F. graminearum was associated with warmer/humid conditions. F. avenaceum and F. culmorum were both associated with niches of cooler/wet/humid conditions. Two Microdochium species were associated with regions of relatively cool/moderate temperatures and frequent rainfalls of short duration. The results also suggested that environmental conditions differentially affect the infection and colonization processes, and the comparative abundance of the six species.

Resource Utilization and Environmental and Spatio-Temporal Overlap of a Hilltopping Lycaenid Butterfly Community in the Colombian Andes

PubMed Central

Prieto, Carlos; Dahners, Hans W.

2009-01-01

Coexistence by a great number of species could reflect niche segregation at several resource axes. Differences in the use of a hilltop as mating site for a Eumaeini (Lycaenidae) community were measured to test whether niche segregation exists within this group. Specimens were collected throughout 21 samplings between July-October of 2004 and July-October of 2005. Two environmental variables and three temporal-spacial variables were analyzed utilizing null models with three randomization algorithms. Significant differences were found among the species with respect to utilization of vertical space, horizontal space, temporary distribution and environmental temperature. The species did not show significant differences with respect to light intensity. For all samplings, the niche overlap observed in the two environmental variables were higher or significantly higher than expected by chance, suggesting that niche segregation does not exist due to competition within these variables. Similar results were observed for temporal distribution. Some evidence of niche segregation was found in vertical space and horizontal space variables where some samples presented lower overlap than expected by chance. The results pointed out that community's assemblage could be mainly shaped in two ways. The first is that species with determined habitat requirements fit into unoccupied niche spaces. The second is by niche segregation in the vertical space distribution variable. PMID:19613456

Environmental Influences on the Fish Assemblage of the Humber Estuary, U.K.

NASA Astrophysics Data System (ADS)

Marshall, S.; Elliott, M.

1998-02-01

Salinity, temperature, turbidity and dissolved oxygen were measured in conjunction with a series of fish samples taken by a 2 m beam trawl from 14 sites throughout the Humber estuary, U.K., over the period April 1992 to November 1994. Sediment type was not measured as the literature indicates that the area is homogeneous. The influences of environmental factors and the characteristics of the fish assemblage were analysed using a range of multivariate techniques, including two-way indicator species analysis, canonical correspondence analysis, principal components analysis and Spearman rank correlation. The analyses indicate that salinity is the dominant factor influencing the distribution of the species, with temperature also having a major influence. Of the species examined, whiting (Merlangius merlangus), sole (Solea solea), flounder (Pleuronectes flesus), sprat (Sprattus sprattus) and herring (Clupea harengus) showed a correlation in distribution to temperature, sole, plaice (Pleuronectes platessa), pogge (Agonus cataphractus) and stickleback (Gasterosteus aculeatus) to salinity, and whiting, flounder, pogge and stickleback to dissolved oxygen. Only cod (Gadus morhua) showed a correlation with tidal state, while whiting, pogge and stickleback were correlated to depth. Unlike in some other estuaries, turbidity did not influence the composition of the fish assemblage. Temperature and salinity fluctuations appear to influence different aspects of the community, with temperature proving to be the best predictor of total abundance, while salinity influenced the species richness and total biomass. The analyses demonstrate the most important variables with regard to environmental-biotic interactions, although they also indicate that the variables measured do not account for all of the observed variation in fish biomass and abundance.

Topographic heterogeneity and temperature amplitude explain species richness patterns of birds in the Qinghai-Tibetan Plateau.

PubMed

Zhang, Chunlan; Quan, Qing; Wu, Yongjie; Chen, Youhua; He, Peng; Qu, Yanhua; Lei, Fumin

2017-04-01

Large-scale patterns of species richness have gained much attention in recent years; however, the factors that drive high species richness are still controversial in local regions, especially in highly diversified montane regions. The Qinghai-Tibetan Plateau (QTP) and the surrounding mountains are biodiversity hot spots due to a high number of endemic montane species. Here, we explored the factors underlying this high level of diversity by studying the relationship between species richness and environmental variables. The richness patterns of 758 resident bird species were summarized at the scale of 1°×1° grid cell at different taxonomic levels (order, family, genus, and species) and in different taxonomic groups (Passeriformes, Galliformes, Falconiformes, and Columbiformes). These richness patterns were subsequently analyzed against habitat heterogeneity (topographical heterogeneity and land cover), temperature amplitude (annual temperature, annual precipitation, precipitation seasonality, and temperature seasonality) and a vegetation index (net primary productivity). Our results showed that the highest richness was found in the southeastern part of the QTP, the eastern Himalayas. The lowest richness was observed in the central plateau of the QTP. Topographical heterogeneity and temperature amplitude are the primary factors that explain overall patterns of species richness in the QTP, although the specific effect of each environmental variable varies between the different taxonomic groups depending on their own evolutionary histories and ecological requirements. High species richness in the southeastern QTP is mostly due to highly diversified habitat types and temperature zones along elevation gradients, whereas the low species richness in the central plateau of the QTP may be due to environmental and energetic constraints, as the central plateau is harsh environment.

How important are coastal fronts to albacore tuna (Thunnus alalunga) habitat in the Northeast Pacific Ocean?

NASA Astrophysics Data System (ADS)

Nieto, Karen; Xu, Yi; Teo, Steven L. H.; McClatchie, Sam; Holmes, John

2017-01-01

We used satellite sea surface temperature (SST) data to characterize coastal fronts and then tested the effects of the fronts and other environmental variables on the distribution of the albacore tuna (Thunnus alalunga) catches in the coastal areas (from the coast to 200 nm offshore) of the Northeast Pacific Ocean. A boosted regression tree (BRT) model was used to explain the spatial and temporal patterns in albacore tuna catch per unit effort (CPUE) (1988-2011), using frontal features (distance to the front and temperature gradient), and other environmental variables like SST, surface chlorophyll concentration (chlorophyll), and geostrophic currents as explanatory variables. Based on over two decades of high-resolution data, the modeled results confirmed previous findings that albacore CPUE distribution is strongly influenced by SST and chlorophyll at fishing locations, and the distance of fronts from the coast (DFRONT-COAST), albeit with substantial seasonal and interannual variation. Albacore CPUEs were higher near warm, low chlorophyll oceanic waters, and near SST fronts. We performed sequential leave-one-year-out cross-validations for all years and found that the relationships in the BRT models were robust for the entire study period. Spatial distributions of model-predicted albacore CPUE were similar to observations, but the model was unable to predict very high CPUEs in some areas. These results help to explain previously observed variability in albacore CPUE and will likely help improve international fisheries management in the face of environmental changes.

Remotely Sensed Environmental Conditions and Malaria Mortality in Three Malaria Endemic Regions in Western Kenya.

PubMed

Sewe, Maquins Odhiambo; Ahlm, Clas; Rocklöv, Joacim

2016-01-01

Malaria is an important cause of morbidity and mortality in malaria endemic countries. The malaria mosquito vectors depend on environmental conditions, such as temperature and rainfall, for reproduction and survival. To investigate the potential for weather driven early warning systems to prevent disease occurrence, the disease relationship to weather conditions need to be carefully investigated. Where meteorological observations are scarce, satellite derived products provide new opportunities to study the disease patterns depending on remotely sensed variables. In this study, we explored the lagged association of Normalized Difference Vegetation Index (NVDI), day Land Surface Temperature (LST) and precipitation on malaria mortality in three areas in Western Kenya. The lagged effect of each environmental variable on weekly malaria mortality was modeled using a Distributed Lag Non Linear Modeling approach. For each variable we constructed a natural spline basis with 3 degrees of freedom for both the lag dimension and the variable. Lag periods up to 12 weeks were considered. The effect of day LST varied between the areas with longer lags. In all the three areas, malaria mortality was associated with precipitation. The risk increased with increasing weekly total precipitation above 20 mm and peaking at 80 mm. The NDVI threshold for increased mortality risk was between 0.3 and 0.4 at shorter lags. This study identified lag patterns and association of remote- sensing environmental factors and malaria mortality in three malaria endemic regions in Western Kenya. Our results show that rainfall has the most consistent predictive pattern to malaria transmission in the endemic study area. Results highlight a potential for development of locally based early warning forecasts that could potentially reduce the disease burden by enabling timely control actions.

Relative Linkages of Stream Dissolved Oxygen with the Hydroclimatic and Biogeochemical Drivers across the Gulf Coast of U.S.A.

NASA Astrophysics Data System (ADS)

Gebreslase, A. K.; Abdul-Aziz, O. I.

2017-12-01

Dynamics of coastal stream water quality is influenced by a multitude of interacting environmental drivers. A systematic data analytics approach was employed to determine the relative linkages of stream dissolved oxygen (DO) with the hydroclimatic and biogeochemical variables across the Gulf Coast of U.S.A. Multivariate pattern recognition techniques of PCA and FA, alongside Pearson's correlation matrix, were utilized to examine the interrelation of variables at 36 water quality monitoring stations from USGS NWIS and EPA STORET databases. Power-law based partial least square regression models with a bootstrap Monte Carlo procedure (1000 iterations) were developed to estimate the relative linkages of dissolved oxygen with the hydroclimatic and biogeochemical variables by appropriately resolving multicollinearity (Nash-Sutcliffe efficiency = 0.58-0.94). Based on the dominant drivers, stations were divided into four environmental regimes. Water temperature was the dominant driver of DO in the majority of streams, representing most the northern part of Gulf Coast states. However, streams in the southern part of Texas and Florida showed a dominant pH control on stream DO. Further, streams representing the transition zone of the two environmental regimes showed notable controls of multiple drivers (i.e., water temperature, stream flow, and specific conductance) on the stream DO. The data analytics research provided profound insight to understand the dynamics of stream DO with the hydroclimatic and biogeochemical variables. The knowledge can help water quality managers in formulating plans for effective stream water quality and watershed management in the U.S. Gulf Coast. Keywords Data analytics, coastal streams, relative linkages, dissolved oxygen, environmental regimes, Gulf Coast, United States.

An analysis of controls on fire activity in boreal Canada: comparing models built with different temporal resolutions

Treesearch

Marc-Andre Parisien; Sean A. Parks; Meg A. Krawchuk; John M. Little; Mike D. Flannigan; Lynn M. Gowman; Max A. Moritz

2014-01-01

Fire regimes of the Canadian boreal forest are driven by certain environmental factors that are highly variable from year to year (e.g., temperature, precipitation) and others that are relatively stable (e.g., land cover, topography). Studies examining the relative influence of these environmental drivers on fire activity suggest that models making explicit use of...

Thermal conditions within tree cavities in ponderosa pine (Pinus ponderosa) forests: potential implications for cavity users.

PubMed

Vierling, Kerri T; Lorenz, Teresa J; Cunningham, Patrick; Potterf, Kelsi

2018-04-01

Tree cavities provide critical roosting and breeding sites for multiple species, and thermal environments in these cavities are important to understand. Our objectives were to (1) describe thermal characteristics in cavities between June 3 and August 9, 2014, and (2) investigate the environmental factors that influence cavity temperatures. We placed iButtons in 84 different cavities in ponderosa pine (Pinus ponderosa) forests in central Washington, and took hourly measurements for at least 8 days in each cavity. Temperatures above 40 °C are generally lethal to developing avian embryos, and ~ 18% of the cavities had internal temperatures of ≥ 40 °C for at least 1 h of each day. We modeled daily maximum cavity temperature, the amplitude of daily cavity temperatures, and the difference between the mean internal cavity and mean ambient temperatures as a function of several environmental variables. These variables included canopy cover, tree diameter at cavity height, cavity volume, entrance area, the hardness of the cavity body, the hardness of the cavity sill (which is the wood below the cavity entrance which forms the barrier between the cavity and the external environment), and sill width. Ambient temperature had the largest effect size for maximum cavity temperature and amplitude. Larger trees with harder sills may provide more thermally stable cavity environments, and decayed sills were positively associated with maximum cavity temperatures. Summer temperatures are projected to increase in this region, and additional research is needed to determine how the thermal environments of cavities will influence species occupancy, breeding, and survival.

Thermal conditions within tree cavities in ponderosa pine (Pinus ponderosa) forests: potential implications for cavity users

NASA Astrophysics Data System (ADS)

Vierling, Kerri T.; Lorenz, Teresa J.; Cunningham, Patrick; Potterf, Kelsi

2017-11-01

Tree cavities provide critical roosting and breeding sites for multiple species, and thermal environments in these cavities are important to understand. Our objectives were to (1) describe thermal characteristics in cavities between June 3 and August 9, 2014, and (2) investigate the environmental factors that influence cavity temperatures. We placed iButtons in 84 different cavities in ponderosa pine (Pinus ponderosa) forests in central Washington, and took hourly measurements for at least 8 days in each cavity. Temperatures above 40 °C are generally lethal to developing avian embryos, and 18% of the cavities had internal temperatures of ≥ 40 °C for at least 1 h of each day. We modeled daily maximum cavity temperature, the amplitude of daily cavity temperatures, and the difference between the mean internal cavity and mean ambient temperatures as a function of several environmental variables. These variables included canopy cover, tree diameter at cavity height, cavity volume, entrance area, the hardness of the cavity body, the hardness of the cavity sill (which is the wood below the cavity entrance which forms the barrier between the cavity and the external environment), and sill width. Ambient temperature had the largest effect size for maximum cavity temperature and amplitude. Larger trees with harder sills may provide more thermally stable cavity environments, and decayed sills were positively associated with maximum cavity temperatures. Summer temperatures are projected to increase in this region, and additional research is needed to determine how the thermal environments of cavities will influence species occupancy, breeding, and survival.

Stress modulation of cellular metabolic sensors: interaction of stress from temperature and rainfall on the intertidal limpet Cellana toreuma.

PubMed

Dong, Yun-Wei; Han, Guo-Dong; Huang, Xiong-Wei

2014-09-01

In the natural environment, organisms are exposed to large variations in physical conditions. Quantifying such physiological responses is, however, often performed in laboratory acclimation studies, in which usually only a single factor is varied. In contrast, field acclimatization may expose organisms to concurrent changes in several environmental variables. The interactions of these factors may have strong effects on organismal function. In particular, rare events that occur stochastically and have relatively short duration may have strong effects. The present experiments studied levels of expression of several genes associated with cellular stress and metabolic regulation in a field population of limpet Cellana toreuma that encountered a wide range of temperatures plus periodic rain events. Physiological responses to these variable conditions were quantified by measuring levels of mRNA of genes encoding heat-shock proteins (Hsps) and metabolic sensors (AMPKs and Sirtuin 1). Our results reveal high ratios of individuals in upregulation group of stress-related gene expression at high temperature and rainy days, indicating the occurrence of stress from both prevailing high summer temperatures and occasional rainfall during periods of emersion. At high temperature, stress due to exposure to rainfall may be more challenging than heat stress alone. The highly variable physiological performances of limpets in their natural habitats indicate the possible differences in capability for physiological regulation among individuals. Our results emphasize the importance of studies of field acclimatization in unravelling the effects of environmental change on organisms, notably in the context of multiple changes in abiotic factors that are accompanying global change. © 2014 John Wiley & Sons Ltd.

Physiological and perceived health effects from daily changes in air pollution and weather among persons with heart failure: a panel study.

PubMed

Goldberg, Mark S; Wheeler, Amanda J; Burnett, Richard T; Mayo, Nancy E; Valois, Marie-France; Brophy, James M; Giannetti, Nadia

2015-01-01

We carried out this daily diary panel study in Montreal, Quebec, to determine whether oxygen saturation, pulse rate, blood pressure, self-rated health, and shortness of breath at night were associated with concentrations of indoor carbon monoxide (CO), and indoor and outdoor fine particles (PM2.5), temperature, and relative humidity. Over a 2-month consecutive period between 2008 and 2010, we measured daily indoor and outdoor levels of the air pollutants and weather variables and 55 subjects measured their daily health and other variables. To estimate the associations between the health outcomes and the environmental exposures, we used a mixed effects regression model using an autoregressive model of order-one and we adjusted for month and day and personal variables. The general pattern of associations can be summarized as follows: oxygen saturation was reduced for increases in indoor- and outdoor-PM2.5 and temperature. Pulse rate increased on the concurrent day for increases in indoor CO and PM2.5. Diastolic blood pressure increased with increasing indoor and outdoor PM2.5 and relative humidity. Systolic blood pressure increased with indoor PM2.5 and decreased with increasing indoor and outdoor temperature. Self-rated health diminished with increases in outdoor PM2.5 and indoor and outdoor temperature. Self-reported shortness of breath at night increased with increasing indoor and outdoor temperatures. Health in heart failure is affected in the short term by personal and environmental conditions that are manifest in intermediate physiological parameters.

Shell architecture: a novel proxy for paleotemperature reconstructions?

NASA Astrophysics Data System (ADS)

Milano, Stefania; Nehrke, Gernot; Wanamaker, Alan D., Jr.; Witbaard, Rob; Schöne, Bernd R.

2017-04-01

Mollusk shells are unique high-resolution paleoenvironmental archives. Their geochemical properties, such as oxygen isotope composition (δ18Oshell) and element-to-calcium ratios, are routinely used to estimate past environmental conditions. However, the existing proxies have certain drawbacks that can affect paleoreconstruction robustness. For instance, the estimation of water temperature of brackish and near-shore environments can be biased by the interdependency of δ18Oshell from multiple environmental variables (water temperature and δ18Owater). Likely, the environmental signature can be masked by physiological processes responsible for the incorporation of trace elements into the shell. The present study evaluated the use of shell structural properties as alternative environmental proxies. The sensitivity of shell architecture at µm and nm-scale to the environment was tested. In particular, the relationship between water temperature and microstructure formation was investigated. To enable the detection of potential structural changes, the shells of the marine bivalves Cerastoderma edule and Arctica islandica were analyzed with Scanning Electron Microscopy (SEM), nanoindentation and Confocal Raman Microscopy (CRM). These techniques allow a quantitative approach to the microstructural analysis. Our results show that water temperature induces a clear response in shell microstructure. A significant alteration in the morphometric characteristics and crystallographic orientation of the structural units was observed. Our pilot study suggests that shell architecture records environmental information and it has potential to be used as novel temperature proxy in near-shore and open ocean habitats.

Organismal versus Environmental Control of the Carbon Isotope Composition of Dicot Angiosperm Pollen: Implications for Paleoenvironmental Reconstruction

NASA Astrophysics Data System (ADS)

King, D. P.; Schubert, B.; Foelber, K.; Jahren, H.

2011-12-01

The prevalence and diagenetic resilience of palynomorphs in Proterozoic and Phanerozoic sediments has led researchers to investigate its potential as an environmental proxy based on its stable isotope composition. Towards this, Loader and Hemming (2001), noted that the carbon isotope composition (δ13C) of modern Pinus sylvestris pollen exine correlates with the developmental period temperature (°C) of the pollen (R2=0.68), implying that the δ13C of gymnosperm pollen could be quantitatively utilized as a paleotemperature proxy. However, the majority of pollen-producing organisms during the last ~120 million years have been angiosperms, which are subject to complex internal signaling for reproduction, in addition to environmental triggers. Because these internal signals control the relative proportion of lipids, long-chain fatty acids, and polysaccharides within pollen grains, we hypothesized that the δ13C variability in pollen (δ13Cpollen) from several plants subject to the same external environmental parameters is of the same magnitude as the amount attributed to the environment for gymnosperms. Within growth chambers, the test organism (Brassica rapa) was cultivated under constant light, water, pCO2, and nutrient supply, but exhibited average δ13Cpollen variability = 4.35% within any chamber (n = 6 to 8 plants per chamber). Field experiments were also conducted in which the pollen from the test organism (Hibiscus spp.) was sampled from several botanical gardens within the state of Hawaii. Pollen collected from any one botanical garden exhibited an average δ13Cpollen variability = 4.5% (up to 5 plants per garden). Upon comparing chambers operating at different temperatures (17°C to 32°C), we discovered no correlation (R2=0.01) between the developmental period temperature (°C) and the δ13C of B. rapa pollen; similarly, no correlation was found between the δ13C of Hibiscus pollen and its developmental period temperature (°C) (R2=0.12). This work underscores the lack of consistent environmental control over the δ13C value of pollen, and suggests that the carbon isotope composition of dicot pollen cannot be used to determine paleotemperatures. Future work centers on our hypothesis that the δ13C variability in angiosperm pollen results from differential reproductive potency and associated differences in the percentages of lipids, long-chain fatty acids, and polysaccharides within pollen. Towards this we will quantify the relationship between the chemical composition of flower-aggregate pollen and its δ13C value, given the δ13C value of isolated end-member constituents.

A review of precipitation and temperature control on seedling emergence and establishment for ponderosa and lodgepole pine forest regeneration

Treesearch

M. D. Petrie; A. M. Wildeman; J. B. Bradford; Robert Hubbard; W. K. Lauenroth

2016-01-01

The persistence of ponderosa pine and lodgepole pine forests in the 21st century depends to a large extent on how seedling emergence and establishment are influenced by driving climate and environmental variables, which largely govern forest regeneration. We surveyed the literature, and identified 96 publications that reported data on dependent variables of seedling...

The Role of Ocean Currents in the Temperature Selection of Plankton: Insights from an Individual-Based Model

PubMed Central

Hellweger, Ferdi L.; van Sebille, Erik; Calfee, Benjamin C.; Chandler, Jeremy W.; Zinser, Erik R.; Swan, Brandon K.; Fredrick, Neil D.

2016-01-01

Biogeography studies that correlate the observed distribution of organisms to environmental variables are typically based on local conditions. However, in cases with substantial translocation, like planktonic organisms carried by ocean currents, selection may happen upstream and local environmental factors may not be representative of those that shaped the local population. Here we use an individual-based model of microbes in the global surface ocean to explore this effect for temperature. We simulate up to 25 million individual cells belonging to up to 50 species with different temperature optima. Microbes are moved around the globe based on a hydrodynamic model, and grow and die based on local temperature. We quantify the role of currents using the “advective temperature differential” metric, which is the optimum temperature of the most abundant species from the model with advection minus that from the model without advection. This differential depends on the location and can be up to 4°C. Poleward-flowing currents, like the Gulf Stream, generally experience cooling and the differential is positive. We apply our results to three global datasets. For observations of optimum growth temperature of phytoplankton, accounting for the effect of currents leads to a slightly better agreement with observations, but there is large variability and the improvement is not statistically significant. For observed Prochlorococcus ecotype ratios and metagenome nucleotide divergence, accounting for advection improves the correlation significantly, especially in areas with relatively strong poleward or equatorward currents. PMID:27907181

Regional comparison of tundra carbon budget response over the Alaska North Slope to varying environmental conditions as informed by in situ and flux tower measurements, remote sensing and biophysical modeling

NASA Astrophysics Data System (ADS)

Shirley, S.; Watts, J. D.; Kimball, J. S.; Zhang, Z.; Poulter, B.; Klene, A. E.; Jones, L. A.; Kim, Y.; Oechel, W. C.; Zona, D.; Euskirchen, E. S.

2017-12-01

A warming Arctic climate is contributing to shifts in landscape moisture and temperature regimes, a shortening of the non-frozen season, and increases in the depth of annual active layer. The changing environmental conditions make it difficult to determine whether tundra ecosystems are a carbon sink or source. At present, eddy covariance flux towers and biophysical measurements within the tower footprint provide the most direct assessment of change to the tundra carbon balance. However, these measurements have a limited spatial footprint and exist over relatively short timescales. Thus, terrestrial ecosystem models are needed to provide an improved understanding of how changes in landscape environmental conditions impact regional carbon fluxes. This study examines the primary drivers thought to affect the magnitude and variability of tundra-atmosphere CO2 and CH4 fluxes over the Alaska North Slope. Also investigated is the ability of biophysical models to capture seasonal flux characteristics over the 9 tundra tower sites examined. First, we apply a regression tree approach to ascertain which remotely sensed environmental variables best explain observed variability in the tower fluxes. Next, we compare flux estimates obtained from multiple process models including Terrestrial Carbon Flux (TCF) and the Lund-Potsdam-Jena Wald Schnee und Landschaft (LPJ-wsl), and Soil Moisture Active Passive Level 4 Carbon (SMAP L4_C) products. Our results indicate that out of 7 variables examined vegetation greenness, temperature, and moisture are more significant predictors of carbon flux magnitude over the tundra tower sites. This study found that satellite data-driven models, due to the ability of remote sensing instruments to capture the physical principles and processes driving tundra carbon flux, are more effective at estimating the magnitude and spatiotemporal variability of CO2 and CH4 fluxes in northern high latitude ecosystems.

[Influence of road on breeding habitat of Nipponia nippon based on MaxEnt model].

PubMed

Zhang, Hui; Gao, Ji Xi; Ma, Meng Xiao; Shao, Fang Ze; Wang, Qiao; Li, Guang Yu; Qiu, Jie; Zhou, Ke Xin

2017-04-18

Quantitative study on effects of roads on suitable breeding habitats of wildlife is one of topics that need in-depth research in road ecology. Crested ibis (Nipponia nippon), a first class nationally protected bird species, is the species of interest in this research. Using the Maximum Entropy Models (MaxEnt) in the Species Distribution Model (SDM) toolbox of ArcGIS, autocorrelation of environmental variables were analyzed and environmental variables with r>0.8 were removed. Ten environmental variables were chosen as impact factors for the breeding habitat of crested ibis, including mean temperature of coldest quarter, landscape type, normalized difference vegetation index(NDVI), slope, aspect, distance to waters, distance to paddy field, distance to high-grade roads (expressway, national way, provincial way), and distance to low-grade roads (country road). By analyzing the contribution rate of each environmental variable, the results showed that the mean temperature of coldest quarter, landscape type, distance to paddy field, and distance to high-grade roads were the main factors determining breeding habitat of crested ibis. The suitable distribution of crested ibis' nesting area was under the following scenarios: variable road present (scenario1), high-grade road absent (scenario2), and low-grade road absent (scenario 3). The results showed that the presence of roads affected suitable nesting areas of crested ibis with high-grade roads showing a larger influence than low-grade roads. The presence of high-grade roads and low-grade roads decreased the suitable nesting areas of crested ibis by 66.23 and 35.69 km 2 , respectively. The crested ibis preferred to nest in areas distant from high-grade roads, with an average road avoidance distance of 1500 m. This study was of great significance for formulating management measures to protect crested ibis and provide a reference for quantitative assessment on impacts of engineering and construction projects on wildlife.

Discerning environmental factors affecting current tree growth in Central Europe.

PubMed

Cienciala, Emil; Russ, Radek; Šantrůčková, Hana; Altman, Jan; Kopáček, Jiří; Hůnová, Iva; Štěpánek, Petr; Oulehle, Filip; Tumajer, Jan; Ståhl, Göran

2016-12-15

We examined the effect of individual environmental factors on the current spruce tree growth assessed from a repeated country-level statistical landscape (incl. forest) survey in the Czech Republic. An extensive set of variables related to tree size, competition, site characteristics including soil texture, chemistry, N deposition and climate was tested within a random-effect model to explain growth in the conditions of dominantly managed forest ecosystems. The current spruce basal area increment was assessed from two consecutive landscape surveys conducted in 2008/2009 and six years later in 2014/2015. Tree size, age and competition within forest stands were found to be the dominant explanatory variables, whereas the expression of site characteristics, environmental and climatic drives was weaker. The significant site variables affecting growth included soil C/N ratio and soil exchangeable acidity (pH KCl; positive response) reflecting soil chemistry, long-term N-deposition (averaged since 1975) in combination with soil texture (clay content) and Standardized Precipitation Index (SPI), a drought index expressing moisture conditions. Sensitivity of growth to N-deposition was positive, although weak. SPI was positively related to and significant in explaining tree growth when expressed for the growth season. Except SPI, no significant relation of growth was determined to altitude-related variables (temperature, growth season length). We identified the current spruce growth optimum at elevations about 800ma.s.l. or higher in the conditions of the country. This suggests that at lower elevations, limitation by a more pronounced water deficit dominates, whereas direct temperature limitation may concern the less frequent higher elevations. The mixed linear model of spruce tree growth explained 55 and 65% of the variability with fixed and random effects included, respectively, and provided new insights on the current spruce tree growth and factors affecting it within the environmental gradients of the country. Copyright © 2016 Elsevier B.V. All rights reserved.

Potential distribution of the viral haemorrhagic septicaemia virus in the Great Lakes region

USGS Publications Warehouse

Escobar, Luis E.; Kurath, Gael; Escobar-Dodero, Joaquim; Craft, Meggan E.; Phelps, Nicholas B.D.

2017-01-01

Viral haemorrhagic septicaemia virus (VHSV) genotype IVb has been responsible for large-scale fish mortality events in the Great Lakes of North America. Anticipating the areas of potential VHSV occurrence is key to designing epidemiological surveillance and disease prevention strategies in the Great Lakes basin. We explored the environmental features that could shape the distribution of VHSV, based on remote sensing and climate data via ecological niche modelling. Variables included temperature measured during the day and night, precipitation, vegetation, bathymetry, solar radiation and topographic wetness. VHSV occurrences were obtained from available reports of virus confirmation in laboratory facilities. We fit a Maxent model using VHSV-IVb reports and environmental variables under different parameterizations to identify the best model to determine potential VHSV occurrence based on environmental suitability. VHSV reports were generated from both passive and active surveillance. VHSV occurrences were most abundant near shore sites. We were, however, able to capture the environmental signature of VHSV based on the environmental variables employed in our model, allowing us to identify patterns of VHSV potential occurrence. Our findings suggest that VHSV is not at an ecological equilibrium and more areas could be affected, including areas not in close geographic proximity to past VHSV reports.

Mapping the potential distribution of the invasive Red Shiner, Cyprinella lutrensis (Teleostei: Cyprinidae) across waterways of the conterminous United States

USGS Publications Warehouse

Poulos, Helen M.; Chernoff, Barry; Fuller, Pam L.; Butman, David

2012-01-01

Predicting the future spread of non-native aquatic species continues to be a high priority for natural resource managers striving to maintain biodiversity and ecosystem function. Modeling the potential distributions of alien aquatic species through spatially explicit mapping is an increasingly important tool for risk assessment and prediction. Habitat modeling also facilitates the identification of key environmental variables influencing species distributions. We modeled the potential distribution of an aggressive invasive minnow, the red shiner (Cyprinella lutrensis), in waterways of the conterminous United States using maximum entropy (Maxent). We used inventory records from the USGS Nonindigenous Aquatic Species Database, native records for C. lutrensis from museum collections, and a geographic information system of 20 raster climatic and environmental variables to produce a map of potential red shiner habitat. Summer climatic variables were the most important environmental predictors of C. lutrensis distribution, which was consistent with the high temperature tolerance of this species. Results from this study provide insights into the locations and environmental conditions in the US that are susceptible to red shiner invasion.

Climate variability, social and environmental factors, and ross river virus transmission: research development and future research needs.

PubMed

Tong, Shilu; Dale, Pat; Nicholls, Neville; Mackenzie, John S; Wolff, Rodney; McMichael, Anthony J

2008-12-01

Arbovirus diseases have emerged as a global public health concern. However, the impact of climatic, social, and environmental variability on the transmission of arbovirus diseases remains to be determined. Our goal for this study was to provide an overview of research development and future research directions about the interrelationship between climate variability, social and environmental factors, and the transmission of Ross River virus (RRV), the most common and widespread arbovirus disease in Australia. We conducted a systematic literature search on climatic, social, and environmental factors and RRV disease. Potentially relevant studies were identified from a series of electronic searches. The body of evidence revealed that the transmission cycles of RRV disease appear to be sensitive to climate and tidal variability. Rainfall, temperature, and high tides were among major determinants of the transmission of RRV disease at the macro level. However, the nature and magnitude of the interrelationship between climate variability, mosquito density, and the transmission of RRV disease varied with geographic area and socioenvironmental condition. Projected anthropogenic global climatic change may result in an increase in RRV infections, and the key determinants of RRV transmission we have identified here may be useful in the development of an early warning system. The analysis indicates that there is a complex relationship between climate variability, social and environmental factors, and RRV transmission. Different strategies may be needed for the control and prevention of RRV disease at different levels. These research findings could be used as an additional tool to support decision making in disease control/surveillance and risk management.

Effects of abiotic factors on the nanostructure of diatom frustules-ranges and variability.

PubMed

Su, Yanyan; Lundholm, Nina; Ellegaard, Marianne

2018-05-26

The intricate patterning of diatom silica frustules at nanometer-to-micrometer scales makes them of interest for a wide range of industrial applications. For some of these applications, a specific size range in nanostructure is required and may be achieved by selecting species with the desired properties. However, as all biological materials, diatom frustules exhibit variability in their morphological parameters and this variability can to some extent be affected and controlled by environmental conditions. In this review, we explore the effects of different environmental factors including salinity, heavy metals, temperature, pH, extracellular Si(OH) 4 or Ge(OH) 4 concentration, light regime, UV irradiance, long-term cultivation, and biotic factors on the nanostructure of diatom frustules. This compilation of studies illustrates that it is possible to affect the nanostructure of diatom frustules in vivo by controlling different environmental factors as well as by direct chemical modification of frustules. We compare these methods and present examples of how these changes affect the range of variability as well as comparing the magnitude of size changes of the most promising methods.

Plant growth modeling at the JSC variable pressure growth chamber - An application of experimental design

NASA Technical Reports Server (NTRS)

Miller, Adam M.; Edeen, Marybeth; Sirko, Robert J.

1992-01-01

This paper describes the approach and results of an effort to characterize plant growth under various environmental conditions at the Johnson Space Center variable pressure growth chamber. Using a field of applied mathematics and statistics known as design of experiments (DOE), we developed a test plan for varying environmental parameters during a lettuce growth experiment. The test plan was developed using a Box-Behnken approach to DOE. As a result of the experimental runs, we have developed empirical models of both the transpiration process and carbon dioxide assimilation for Waldman's Green lettuce over specified ranges of environmental parameters including carbon dioxide concentration, light intensity, dew-point temperature, and air velocity. This model also predicts transpiration and carbon dioxide assimilation for different ages of the plant canopy.

Sensitivity of cell-based biosensors to environmental variables.

PubMed

Gilchrist, Kristin H; Giovangrandi, Laurent; Whittington, R Hollis; Kovacs, Gregory T A

2005-01-15

Electrically active living cells cultured on extracellular electrode arrays are utilized to detect biologically active agents. Because cells are highly sensitive to environmental conditions, environmental fluctuations can elicit cellular responses that contribute to the noise in a cell-based biosensor system. Therefore, the characterization and control of environmental factors such as temperature, pH, and osmolarity is critical in such a system. The cell-based biosensor platform described here utilizes the measurement of action potentials from cardiac cells cultured on electrode arrays. A recirculating fluid flow system is presented for use in dose-response experiments that regulates temperature within +/-0.2 degrees C, pH to within +/-0.05 units, and allows no significant change in osmolarity. Using this system, the relationship between the sensor output parameters and environmental variation was quantified. Under typical experimental conditions, beat rate varied approximately 10% per degree change in temperature or per 0.1 unit change in pH. Similar relationships were measured for action potential amplitude, duration, and conduction velocity. For the specific flow system used in this work, the measured environmental sensitivity resulted in an overall beat rate variation of +/-4.7% and an overall amplitude variation of +/-3.3%. The magnitude of the noise due to environmental sensitivity has a large impact on the detection capability of the cell-based system. The significant responses to temperature, pH, and osmolarity have important implications for the use of living cells in detection systems and should be considered in the design and evaluation of such systems.

Reconstruction of Centennial and Millennial-scale Climate and Environmental Variability during the Holocene in the Central Canadian Arctic

NASA Astrophysics Data System (ADS)

Rolland, N.; Porinchu, D.; MacDonald, G.; Moser, K.

2007-12-01

The Arctic and sub-Arctic regions are experiencing dramatic changes in surface temperature, sea-ice extent, glacial melt, river discharge, soil carbon storage and snow cover. According to the IPCC high latitude regions are expected to warm between 4°C and 7°C over the next 100 years. The magnitude of warming and the rate at which it occurs will dwarf any previous warming episodes experienced by latitude regions over the last 11,000 years. It is critical that we improve our understanding of how the Arctic and sub-Arctic regions responded to past periods of warming, especially in light of the changes these regions will be experiencing over the next 100 years. One of the lines of evidence increasingly utilized in multi-proxy paleolimnological research is the Chironomidae (Insecta: Diptera). Also known as non-biting midge flies, chironomids are ubiquitous, frequently the most abundant insects found in freshwater ecosystems and very sensitive to environmental conditions. This research uses Chironomidae to quantitatively characterize climate and environmental conditions of the continental interior of Arctic Canada during the Holocene. Spanning four major vegetation zones (boreal forest, forest-tundra, birch tundra and herb tundra), the surface samples of 80 lakes recovered from the central Canadian Arctic were used to assess the relationship of 22 environmental variables with the chironomid distribution. Redundancy analysis (RDA) identified four variables, total Kjeldahl nitrogen (TKN), pH, summer surface water temperature (SSWT) and depth, which best explain the variance in the distribution of chironomids within these ecoregions. In order to provide new quantitative estimates of SSWT, a 1-component weighted average partial least square (WA-PLS) model was developed (r2jack = 0.76, RMSEP = 1.42°C) and applied downcore in two low arctic continental Nunavut lakes located approximately 50 km and 200 km north of modern treeline. This robust midge-inferred temperature reconstruction of the Holocene thermal conditions will then be compared with previous research describing vegetation development in this region. This study provides new and important data which helps to further resolve millennial and centennial-scale climate variability in the central Canadian Arctic during the Holocene.

Integration of oceanographic data with fin whale calling presence in the Bering Sea

NASA Astrophysics Data System (ADS)

Dasarathy, S.; Berchok, C.; Stabeno, P. J.; Crance, J.

2016-02-01

Through the integration of environmental data with passive acoustic monitoring, it is possible to investigate whether fin whale (Balaenoptera physalus) presence is influenced by environmental factors. Fin whale calling activity and concurrent environmental variables were analyzed from May 2012 to September 2013. These data were collected from passive acoustic and oceanographic moorings located in the Bering Sea. Fin whale calling presence was strongly correlated with three of the eight parameters analyzed: ice concentration, chlorophyll (a proxy for primary production), and temperature. Fin whale calling was negatively correlated with ice concentration; as ice concentration increased, fin whale calling decreased. A strong positive correlation was observed between fin whale calling and chlorophyll. A large spike in chlorophyll concentration in July 2013 preceded fin whale calling at the northern location. Fin whale calling also increased concurrently with a mixing of the water column (evidenced in the temperature data) at a depth of 30 to 50m. Peaks in chlorophyll concentration occurred after the mixing of the water column, and followed an increase in fin whale calling. These data illustrate the relationship between fin whale presence and environmental variables in the Bering Sea. These correlations may be used to predict the impact of climate change on fin whale populations in the rapidly changing environment of the Bering Sea.

Niche partitioning and biogeography of high light adapted Prochlorococcus across taxonomic ranks in the North Pacific

PubMed Central

Larkin, Alyse A; Blinebry, Sara K; Howes, Caroline; Lin, Yajuan; Loftus, Sarah E; Schmaus, Carrie A; Zinser, Erik R; Johnson, Zackary I

2016-01-01

The distribution of major clades of Prochlorococcus tracks light, temperature and other environmental variables; yet, the drivers of genomic diversity within these ecotypes and the net effect on biodiversity of the larger community are poorly understood. We examined high light (HL) adapted Prochlorococcus communities across spatial and temporal environmental gradients in the Pacific Ocean to determine the ecological drivers of population structure and diversity across taxonomic ranks. We show that the Prochlorococcus community has the highest diversity at low latitudes, but seasonality driven by temperature, day length and nutrients adds complexity. At finer taxonomic resolution, some ‘sub-ecotype' clades have unique, cohesive responses to environmental variables and distinct biogeographies, suggesting that presently defined ecotypes can be further partitioned into ecologically meaningful units. Intriguingly, biogeographies of the HL-I sub-ecotypes are driven by unique combinations of environmental traits, rather than through trait hierarchy, while the HL-II sub-ecotypes appear ecologically similar, thus demonstrating differences among these dominant HL ecotypes. Examining biodiversity across taxonomic ranks reveals high-resolution dynamics of Prochlorococcus evolution and ecology that are masked at phylogenetically coarse resolution. Spatial and seasonal trends of Prochlorococcus communities suggest that the future ocean may be comprised of different populations, with implications for ecosystem structure and function. PMID:26800235

A Unimodal Species Response Model Relating Traits to Environment with Application to Phytoplankton Communities

PubMed Central

Jamil, Tahira; Kruk, Carla; ter Braak, Cajo J. F.

2014-01-01

In this paper we attempt to explain observed niche differences among species (i.e. differences in their distribution along environmental gradients) by differences in trait values (e.g. volume) in phytoplankton communities. For this, we propose the trait-modulated Gaussian logistic model in which the niche parameters (optimum, tolerance and maximum) are made linearly dependent on species traits. The model is fitted to data in the Bayesian framework using OpenBUGS (Bayesian inference Using Gibbs Sampling) to identify according to which environmental variables there is niche differentiation among species and traits. We illustrate the method with phytoplankton community data of 203 lakes located within four climate zones and associated measurements on 11 environmental variables and six morphological species traits of 60 species. Temperature and chlorophyll-a (with opposite signs) described well the niche structure of all species. Results showed that about 25% of the variance in the niche centres with respect to chlorophyll-a were accounted for by traits, whereas niche width and maximum could not be predicted by traits. Volume, mucilage, flagella and siliceous exoskeleton are found to be the most important traits to explain the niche centres. Species were clustered in two groups with different niches structures, group 1 high temperature-low chlorophyll-a species and group 2 low temperature-high chlorophyll-a species. Compared to group 2, species in group 1 had larger volume but lower surface area, had more often flagella but neither mucilage nor siliceous exoskeleton. These results might help in understanding the effect of environmental changes on phytoplankton community. The proposed method, therefore, can also apply to other aquatic or terrestrial communities for which individual traits and environmental conditioning factors are available. PMID:24835582

Influence of Environmental Variables on Gambierdiscus spp. (Dinophyceae) Growth and Distribution

PubMed Central

Xu, Yixiao; Richlen, Mindy L.; Liefer, Justin D.; Robertson, Alison; Kulis, David; Smith, Tyler B.; Parsons, Michael L.; Anderson, Donald M.

2016-01-01

Benthic dinoflagellates in the genus Gambierdiscus produce the ciguatoxin precursors responsible for the occurrence of ciguatera toxicity. The prevalence of ciguatera toxins in fish has been linked to the presence and distribution of toxin-producing species in coral reef ecosystems, which is largely determined by the presence of suitable benthic habitat and environmental conditions favorable for growth. Here using single factor experiments, we examined the effects of salinity, irradiance, and temperature on growth of 17 strains of Gambierdiscus representing eight species/phylotypes (G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri, G. pacificus, G. silvae, Gambierdiscus sp. type 4–5), most of which were established from either Marakei Island, Republic of Kiribati, or St. Thomas, United States Virgin Island (USVI). Comparable to prior studies, growth rates fell within the range of 0–0.48 divisions day-1. In the salinity and temperature studies, Gambierdiscus responded in a near Gaussian, non-linear manner typical for such studies, with optimal and suboptimal growth occurring in the range of salinities of 25 and 45 and 21.0 and 32.5°C. In the irradiance experiment, no mortality was observed; however, growth rates at 55μmol photons · m-2 · s-1 were lower than those at 110–400μmol photons · m-2 · s-1. At the extremes of the environmental conditions tested, growth rates were highly variable, evidenced by large coefficients of variability. However, significant differences in intraspecific growth rates were typically found only at optimal or near-optimal growth conditions. Polynomial regression analyses showed that maximum growth occurred at salinity and temperature levels of 30.1–38.5 and 23.8–29.2°C, respectively. Gambierdiscus growth patterns varied among species, and within individual species: G. belizeanus, G. caribaeus, G. carpenteri, and G. pacificus generally exhibited a wider range of tolerance to environmental conditions, which may explain their broad geographic distribution. In contrast, G. silvae and Gambierdiscus sp. types 4–5 all displayed a comparatively narrow range of tolerance to temperature, salinity, and irradiance. PMID:27074134

Environmental variables associated with vacationers' sun protection at warm weather resorts in North America

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersen, Peter A., E-mail: westone47@gmail.com; Buller, David B.; Walkosz, Barbara J.

Background: Vacationing at sunny, warm weather locations is a risk factor for excessive solar ultraviolet (UV) radiation exposure and skin cancer. Objectives: This study examined the association of environmental variables related to UV levels with vacationers' sun protection. Methods: Vacationers at 41 summer resorts in 17 states and 1 Canadian Province were interviewed (n=3531) and observed (N=4347) during 2012 and 2013. Clothing coverage, sunglasses, and shade use were observed. Use of sunscreen and sunburns were self-reported. Environmental information was recorded by research staff or acquired from ground stations and the weather service. Results: Temperature was positively associated with sun protectionmore » behaviors; however clothing coverage was negatively associated with temperature. Cloud cover was negatively associated with sun protection, with the exception of clothing coverage which was positively associated with it. Elevation showed a mixed pattern of associations with vacationer's sun protection. Latitude of a resort was negatively associated with most sun protection behaviors, such that sun protection increased at more southerly resorts. Similarly, the farther south a vacationer traveled to the resort, the less sun protection they employed. The UV index showed a weak, positive relationship with some sun protection behaviors even when controlling for temperature. Conclusions: Vacationers appeared aware that UV is higher at southern latitudes and may learn UV is intense when living in southern regions. However, many used temperature, an unreliable cue, to judge UV intensity and seemed to adjust clothing for warmth not UV protection. Efforts are needed to help individuals make more accurate sun safety decisions. - Highlights: • Vacationers poorly monitor and protect against environmental ultraviolet radiation (UVR). • On cloudy days vacationers fail to protect against UVR. • Temperature is erroneously used by vacationers as a marker for UVR. • Clothing is used primarily by vacationers for warmth, not UVR protection. • The farther south a vacationer travels, the more likely they are to sunburn.« less

Physical activity levels of older community-dwelling adults are influenced by summer weather variables.

PubMed

Brandon, Caitlin A; Gill, Dawn P; Speechley, Mark; Gilliland, Jason; Jones, Gareth R

2009-04-01

Adequate daily physical activity (PA) is important for maintaining functional capacity and independence in older adults. However, most older adults in Canada do not engage in enough PA to sustain fitness and functional independence. Environmental influences, such as warmer daytime temperatures, may influence PA participation; however, few studies have examined the effect of summertime temperatures on PA levels in older adults. This investigation measured the influence of summertime weather variables on PA in 48 community-dwelling older adults who were randomly recruited from a local seniors' community centre. Each participant wore an accelerometer for a single 7-consecutive-day period (between 30 May and 9 August 2006) during waking hours, and completed a PA logbook to remark on major daily PA events. Local weather variables were collected from a national weather service and compared with PA counts per minute. Regression analysis revealed a curvilinear relationship between log-transformed PA and mean daily temperature (r2 = 0.025; p < 0.05). Linear mixed effects models that accounted for repeated measures nested within individuals were performed for monthly periods, meteorological variables, sex, age, and estimated maximal oxygen consumption, with PA as the dependent variable. Age and Air Quality Index remained significant variables within the model. Higher fitness levels had no effect on allowing individuals to perform more vigorous PA in warmer temperatures.

The Watcombe housing study: the short-term effect of improving housing conditions on the indoor environment.

PubMed

Richardson, George; Barton, Andrew; Basham, Meryl; Foy, Chris; Eick, Susan Ann; Somerville, Margaret

2006-05-15

A three-year study (1999-2001) was initiated in the UK to assess the effect of improving housing conditions in 3-4 bedroom, single-family unit, social rented sector houses on the health of the occupants. The houses were randomised into two groups. Phase I houses received extensive upgrading including wet central heating, on demand ventilation, double-glazed doors, cavity wall and roof/loft insulation. An identical intervention for Phase II houses was delayed for one year. As part of this randomised waiting list study, discrete measurements were made of indoor environmental variables in each house, to assess the short-term effects of improving housing conditions on the indoor environment. Variables representative of indoor environmental conditions were measured in the living room, bedroom and outdoors in each of the three years of the study. In 2000, there was a significant difference between the changes from 1999 to 2000 between Phase I (upgraded) and II (not then upgraded) houses for bedroom temperatures (p=0.002). Changes in wall surface dampness and wall dampness in Phase I houses were also significantly different to the change in Phase II houses in 2000 (p=0.001), but by 2001 the Phase I houses had reverted to the same dampness levels they had before upgrading. The housing upgrades increased bedroom temperatures in all houses. Other indoor environmental variables were not affected.

Head space solid phase microextraction based on nano-structured lead dioxide: application to the speciation of volatile organoselenium in environmental and biological samples.

PubMed

Ghasemi, Ensieh; Farahani, Hadi

2012-10-05

A novel and efficient speciation method based on the nano-structured lead dioxide as stationary phase of head space solid phase microextraction combined with gas chromatography mass spectrometry (GC-MS) was developed for the determination of volatile organoselenium compounds (dimethylselenide (DMSe) and dimethyldiselenide (DMDSe)) in different biological and environmental samples. PbO(2) particles with a diameter in the range of 50-70 nm have been grown on platinum wire via elechtrochemical deposition. The effect of different variables on the extraction efficiency was studied simultaneously using an experimental design. The variables of interest in the HS-SPME were condition of coating preparation, desorption time, stirring rate, desorption temperature, ionic strength, time and temperature of extraction. A Plackett-Burman design was performed for screening in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by a Box-Behnken design (BBD) and the response surface equations were derived. The detection limit and relative standard deviation (RSD) (n=5, c=50 μgL(-1)) for DMSe were 16 ngL(-1) and 4.3%, respectively. They were also obtained for DMDSe as 11ngL(-1) and 4.6%, respectively. The developed technique was found to be applicable to spiked environmental and biological samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Complex interactions between climate change and toxicants: evidence that temperature variability increases sensitivity to cadmium.

PubMed

Kimberly, David A; Salice, Christopher J

2014-07-01

The Intergovernmental Panel on Climate Change projects that global climate change will have significant impacts on environmental conditions including potential effects on sensitivity of organisms to environmental contaminants. The objective of this study was to test the climate-induced toxicant sensitivity (CITS) hypothesis in which acclimation to altered climate parameters increases toxicant sensitivity. Adult Physa pomilia snails were acclimated to a near optimal 22 °C or a high-normal 28 °C for 28 days. After 28 days, snails from each temperature group were challenged with either low (150 μg/L) or high (300 μg/L) cadmium at each temperature (28 or 22 °C). In contrast to the CITS hypothesis, we found that acclimation temperature did not have a strong influence on cadmium sensitivity except at the high cadmium test concentration where snails acclimated to 28 °C were more cadmium tolerant. However, snails that experienced a switch in temperature for the cadmium challenge, regardless of the switch direction, were the most sensitive to cadmium. Within the snails that were switched between temperatures, snails acclimated at 28 °C and then exposed to high cadmium at 22 °C exhibited significantly greater mortality than those snails acclimated to 22 °C and then exposed to cadmium at 28 °C. Our results point to the importance of temperature variability in increasing toxicant sensitivity but also suggest a potentially complex cost of temperature acclimation. Broadly, the type of temporal stressor exposures we simulated may reduce overall plasticity in responses to stress ultimately rendering populations more vulnerable to adverse effects.

Effects of climate change and variability on population dynamics in a long-lived shorebird.

PubMed

van de Pol, Martijn; Vindenes, Yngvild; Saether, Bernt-Erik; Engen, Steinar; Ens, Bruno J; Oosterbeek, Kees; Tinbergen, Joost M

2010-04-01

Climate change affects both the mean and variability of climatic variables, but their relative impact on the dynamics of populations is still largely unexplored. Based on a long-term study of the demography of a declining Eurasian Oystercatcher (Haematopus ostralegus) population, we quantify the effect of changes in mean and variance of winter temperature on different vital rates across the life cycle. Subsequently, we quantify, using stochastic stage-structured models, how changes in the mean and variance of this environmental variable affect important characteristics of the future population dynamics, such as the time to extinction. Local mean winter temperature is predicted to strongly increase, and we show that this is likely to increase the population's persistence time via its positive effects on adult survival that outweigh the negative effects that higher temperatures have on fecundity. Interannual variation in winter temperature is predicted to decrease, which is also likely to increase persistence time via its positive effects on adult survival that outweigh the negative effects that lower temperature variability has on fecundity. Overall, a 0.1 degrees C change in mean temperature is predicted to alter median time to extinction by 1.5 times as many years as would a 0.1 degrees C change in the standard deviation in temperature, suggesting that the dynamics of oystercatchers are more sensitive to changes in the mean than in the interannual variability of this climatic variable. Moreover, as climate models predict larger changes in the mean than in the standard deviation of local winter temperature, the effects of future climatic variability on this population's time to extinction are expected to be overwhelmed by the effects of changes in climatic means. We discuss the mechanisms by which climatic variability can either increase or decrease population viability and how this might depend both on species' life histories and on the vital rates affected. This study illustrates that, for making reliable inferences about population consequences in species in which life history changes with age or stage, it is crucial to investigate the impact of climate change on vital rates across the entire life cycle. Disturbingly, such data are unavailable for most species of conservation concern.

Global potential distribution of Drosophila suzukii (Diptera, Drosophilidae)

PubMed Central

dos Santos, Luana A.; Mendes, Mayara F.; Krüger, Alexandra P.; Blauth, Monica L.; Gottschalk, Marco S.

2017-01-01

Drosophila suzukii (Matsumura) is a species native to Western Asia that is able to pierce intact fruit during egg laying, causing it to be considered a fruit crop pest in many countries. Drosophila suzukii have a rapid expansion worldwide; occurrences were recorded in North America and Europe in 2008, and South America in 2013. Due to this rapid expansion, we modeled the potential distribution of this species using the Maximum Entropy Modeling (MaxEnt) algorithm and the Genetic Algorithm for Ruleset Production (GARP) using 407 sites with known occurrences worldwide and 11 predictor variables. After 1000 replicates, the value of the average area under the curve (AUC) of the model predictions with 1000 replicates was 0.97 for MaxEnt and 0.87 for GARP, indicating that both models had optimal performances. The environmental variables that most influenced the prediction of the MaxEnt model were the annual mean temperature, the maximum temperature of the warmest month, the mean temperature of the coldest quarter and the annual precipitation. The models indicated high environmental suitability, mainly in temperate and subtropical areas in the continents of Asia, Europe and North and South America, where the species has already been recorded. The potential for further invasions of the African and Australian continents is predicted due to the environmental suitability of these areas for this species. PMID:28323903

Environmental preferences of tuna and non-tuna species associated with drifting fish aggregating devices (DFADs) in the Atlantic Ocean, ascertained through fishers' echo-sounder buoys

NASA Astrophysics Data System (ADS)

Lopez, Jon; Moreno, Gala; Lennert-Cody, Cleridy; Maunder, Mark; Sancristobal, Igor; Caballero, Ainhoa; Dagorn, Laurent

2017-06-01

Understanding the relationship between environmental variables and pelagic species concentrations and dynamics is helpful to improve fishery management, especially in a changing environment. Drifting fish aggregating device (DFAD)-associated tuna and non-tuna biomass data from the fishers' echo-sounder buoys operating in the Atlantic Ocean have been modelled as functions of oceanographic (Sea Surface Temperature, Chlorophyll-a, Salinity, Sea Level Anomaly, Thermocline depth and gradient, Geostrophic current, Total Current, Depth) and DFAD variables (DFAD speed, bearing and soak time) using Generalized Additive Mixed Models (GAMMs). Biological interaction (presence of non-tuna species at DFADs) was also included in the tuna model, and found to be significant at this time scale. All variables were included in the analyses but only some of them were highly significant, and variable significance differed among fish groups. In general, most of the fish biomass distribution was explained by the ocean productivity and DFAD-variables. Indeed, this study revealed different environmental preferences for tunas and non-tuna species and suggested the existence of active habitat selection. This improved assessment of environmental and DFAD effects on tuna and non-tuna catchability in the purse seine tuna fishery will contribute to transfer of better scientific advice to regional tuna commissions for the management and conservation of exploited resources.

Environmental triggers of Past Ebola Outbreaks in Africa, 1981 - 2014

NASA Astrophysics Data System (ADS)

Dartevelle, S.; NguyRobertson, A. L.

2016-12-01

Ebola virus, especially its most common and lethal form, Zaire Ebolavirus, has eluded scientists nearly 50 years. What is its primary host? Why does it go dormant to suddenly to reappear full force years later? What are the driving forces behind its intriguing dynamic? It has been surmised that local environmental factors (such as droughts, seasons) might be at play behind the on-and-off Ebola outbreak outbursts. However, so far, no clear lead has been demonstrated making Ebola a constant hidden lethal menace lurking in the environment for many African communities. We have analyzed long-term time-series of three environmental variables that influence the controlling factor behind the cycle of Ebola virus outbreaks: (i) vegetation health, as determined from the Normalized Difference Vegetation Index (NDVI) collected by AVHRR and MODIS satellite sensors, and the weather variables (ii) temperature and (iii) precipitation from the Climate Forecast System ver. 2. Time series data were averaged monthly and spatially over a 100 km grid around past known outbreak locations. Seasonal effects were removed from these time series before applying statistical analyses identifying causal linkages between NDVI, temperature, precipitation and Ebola outbreaks. Likewise, possible tipping-points prior to outbreaks (i.e., early warning signals of an upcoming outbreak) were identified. Our results indicate that there is a causal dynamic link between outbreaks and the three environmental variables examined months prior to an outbreak. This was likely due to an abnormal change in the local precipitation pattern which influence NDVI values and to a lesser extent temperature. Furthermore, our results provide evidence that these factors demonstrate early warning signals of a dynamical system at a tipping-point, prior to a future outbreak. These tipping-point or early warning models may open new ways to furthermore develop forecast models of future Ebola outbreaks. [US Government — Approved for Public Release 16-560].

Genome-Wide Analysis of Yield in Europe: Allelic Effects Vary with Drought and Heat Scenarios1[OPEN

PubMed Central

Millet, Emilie J.; Welcker, Claude; Kruijer, Willem; Negro, Sandra; Coupel-Ledru, Aude; Laborde, Jacques; Bauland, Cyril; Praud, Sebastien; Presterl, Thomas; Usadel, Björn; Charcosset, Alain; Van Eeuwijk, Fred; Tardieu, François

2016-01-01

Assessing the genetic variability of plant performance under heat and drought scenarios can contribute to reduce the negative effects of climate change. We propose here an approach that consisted of (1) clustering time courses of environmental variables simulated by a crop model in current (35 years × 55 sites) and future conditions into six scenarios of temperature and water deficit as experienced by maize (Zea mays L.) plants; (2) performing 29 field experiments in contrasting conditions across Europe with 244 maize hybrids; (3) assigning individual experiments to scenarios based on environmental conditions as measured in each field experiment; frequencies of temperature scenarios in our experiments corresponded to future heat scenarios (+5°C); (4) analyzing the genetic variation of plant performance for each environmental scenario. Forty-eight quantitative trait loci (QTLs) of yield were identified by association genetics using a multi-environment multi-locus model. Eight and twelve QTLs were associated to tolerances to heat and drought stresses because they were specific to hot and dry scenarios, respectively, with low or even negative allelic effects in favorable scenarios. Twenty-four QTLs improved yield in favorable conditions but showed nonsignificant effects under stress; they were therefore associated with higher sensitivity. Our approach showed a pattern of QTL effects expressed as functions of environmental variables and scenarios, allowing us to suggest hypotheses for mechanisms and candidate genes underlying each QTL. It can be used for assessing the performance of genotypes and the contribution of genomic regions under current and future stress situations and to accelerate breeding for drought-prone environments. PMID:27436830

Biodiversity enhances reef fish biomass and resistance to climate change.

PubMed

Duffy, J Emmett; Lefcheck, Jonathan S; Stuart-Smith, Rick D; Navarrete, Sergio A; Edgar, Graham J

2016-05-31

Fishes are the most diverse group of vertebrates, play key functional roles in aquatic ecosystems, and provide protein for a billion people, especially in the developing world. Those functions are compromised by mounting pressures on marine biodiversity and ecosystems. Because of its economic and food value, fish biomass production provides an unusually direct link from biodiversity to critical ecosystem services. We used the Reef Life Survey's global database of 4,556 standardized fish surveys to test the importance of biodiversity to fish production relative to 25 environmental drivers. Temperature, biodiversity, and human influence together explained 47% of the global variation in reef fish biomass among sites. Fish species richness and functional diversity were among the strongest predictors of fish biomass, particularly for the large-bodied species and carnivores preferred by fishers, and these biodiversity effects were robust to potentially confounding influences of sample abundance, scale, and environmental correlations. Warmer temperatures increased biomass directly, presumably by raising metabolism, and indirectly by increasing diversity, whereas temperature variability reduced biomass. Importantly, diversity and climate interact, with biomass of diverse communities less affected by rising and variable temperatures than species-poor communities. Biodiversity thus buffers global fish biomass from climate change, and conservation of marine biodiversity can stabilize fish production in a changing ocean.

Biodiversity enhances reef fish biomass and resistance to climate change

PubMed Central

Duffy, J. Emmett; Lefcheck, Jonathan S.; Navarrete, Sergio A.; Edgar, Graham J.

2016-01-01

Fishes are the most diverse group of vertebrates, play key functional roles in aquatic ecosystems, and provide protein for a billion people, especially in the developing world. Those functions are compromised by mounting pressures on marine biodiversity and ecosystems. Because of its economic and food value, fish biomass production provides an unusually direct link from biodiversity to critical ecosystem services. We used the Reef Life Survey’s global database of 4,556 standardized fish surveys to test the importance of biodiversity to fish production relative to 25 environmental drivers. Temperature, biodiversity, and human influence together explained 47% of the global variation in reef fish biomass among sites. Fish species richness and functional diversity were among the strongest predictors of fish biomass, particularly for the large-bodied species and carnivores preferred by fishers, and these biodiversity effects were robust to potentially confounding influences of sample abundance, scale, and environmental correlations. Warmer temperatures increased biomass directly, presumably by raising metabolism, and indirectly by increasing diversity, whereas temperature variability reduced biomass. Importantly, diversity and climate interact, with biomass of diverse communities less affected by rising and variable temperatures than species-poor communities. Biodiversity thus buffers global fish biomass from climate change, and conservation of marine biodiversity can stabilize fish production in a changing ocean. PMID:27185921

Seasonal patterns of body temperature daily rhythms in group-living Cape ground squirrels Xerus inauris.

PubMed

Scantlebury, Michael; Danek-Gontard, Marine; Bateman, Philip W; Bennett, Nigel C; Manjerovic, Mary Beth; Manjerovic, Mary-Beth; Joubert, Kenneth E; Waterman, Jane M

2012-01-01

Organisms respond to cyclical environmental conditions by entraining their endogenous biological rhythms. Such physiological responses are expected to be substantial for species inhabiting arid environments which incur large variations in daily and seasonal ambient temperature (T(a)). We measured core body temperature (T(b)) daily rhythms of Cape ground squirrels Xerus inauris inhabiting an area of Kalahari grassland for six months from the Austral winter through to the summer. Squirrels inhabited two different areas: an exposed flood plain and a nearby wooded, shady area, and occurred in different social group sizes, defined by the number of individuals that shared a sleeping burrow. Of a suite of environmental variables measured, maximal daily T(a) provided the greatest explanatory power for mean T(b) whereas sunrise had greatest power for T(b) acrophase. There were significant changes in mean T(b) and T(b) acrophase over time with mean T(b) increasing and T(b) acrophase becoming earlier as the season progressed. Squirrels also emerged from their burrows earlier and returned to them later over the measurement period. Greater increases in T(b), sometimes in excess of 5°C, were noted during the first hour post emergence, after which T(b) remained relatively constant. This is consistent with observations that squirrels entered their burrows during the day to 'offload' heat. In addition, greater T(b) amplitude values were noted in individuals inhabiting the flood plain compared with the woodland suggesting that squirrels dealt with increased environmental variability by attempting to reduce their T(a)-T(b) gradient. Finally, there were significant effects of age and group size on T(b) with a lower and less variable T(b) in younger individuals and those from larger group sizes. These data indicate that Cape ground squirrels have a labile T(b) which is sensitive to a number of abiotic and biotic factors and which enables them to be active in a harsh and variable environment.

Seasonal Patterns of Body Temperature Daily Rhythms in Group-Living Cape Ground Squirrels Xerus inauris

PubMed Central

Scantlebury, Michael; Danek-Gontard, Marine; Bateman, Philip W.; Bennett, Nigel C.; Manjerovic, Mary-Beth; Joubert, Kenneth E.; Waterman, Jane M.

2012-01-01

Organisms respond to cyclical environmental conditions by entraining their endogenous biological rhythms. Such physiological responses are expected to be substantial for species inhabiting arid environments which incur large variations in daily and seasonal ambient temperature (Ta). We measured core body temperature (Tb) daily rhythms of Cape ground squirrels Xerus inauris inhabiting an area of Kalahari grassland for six months from the Austral winter through to the summer. Squirrels inhabited two different areas: an exposed flood plain and a nearby wooded, shady area, and occurred in different social group sizes, defined by the number of individuals that shared a sleeping burrow. Of a suite of environmental variables measured, maximal daily Ta provided the greatest explanatory power for mean Tb whereas sunrise had greatest power for Tb acrophase. There were significant changes in mean Tb and Tb acrophase over time with mean Tb increasing and Tb acrophase becoming earlier as the season progressed. Squirrels also emerged from their burrows earlier and returned to them later over the measurement period. Greater increases in Tb, sometimes in excess of 5°C, were noted during the first hour post emergence, after which Tb remained relatively constant. This is consistent with observations that squirrels entered their burrows during the day to ‘offload’ heat. In addition, greater Tb amplitude values were noted in individuals inhabiting the flood plain compared with the woodland suggesting that squirrels dealt with increased environmental variability by attempting to reduce their Ta-Tb gradient. Finally, there were significant effects of age and group size on Tb with a lower and less variable Tb in younger individuals and those from larger group sizes. These data indicate that Cape ground squirrels have a labile Tb which is sensitive to a number of abiotic and biotic factors and which enables them to be active in a harsh and variable environment. PMID:22558324

Range expansion through fragmented landscapes under a variable climate

PubMed Central

Bennie, Jonathan; Hodgson, Jenny A; Lawson, Callum R; Holloway, Crispin TR; Roy, David B; Brereton, Tom; Thomas, Chris D; Wilson, Robert J

2013-01-01

Ecological responses to climate change may depend on complex patterns of variability in weather and local microclimate that overlay global increases in mean temperature. Here, we show that high-resolution temporal and spatial variability in temperature drives the dynamics of range expansion for an exemplar species, the butterfly Hesperia comma. Using fine-resolution (5 m) models of vegetation surface microclimate, we estimate the thermal suitability of 906 habitat patches at the species' range margin for 27 years. Population and metapopulation models that incorporate this dynamic microclimate surface improve predictions of observed annual changes to population density and patch occupancy dynamics during the species' range expansion from 1982 to 2009. Our findings reveal how fine-scale, short-term environmental variability drives rates and patterns of range expansion through spatially localised, intermittent episodes of expansion and contraction. Incorporating dynamic microclimates can thus improve models of species range shifts at spatial and temporal scales relevant to conservation interventions. PMID:23701124

Environmental and management factors affecting the welfare of chickens on commercial farms in the United Kingdom and Denmark stocked at five densities.

PubMed

Jones, T A; Donnelly, C A; Stamp Dawkins, M

2005-08-01

Data from a large commercial-scale experiment in which 10 major broiler producer companies stocked whole houses of birds at 30, 34, 38, 42, and 46 kg/m2 were analyzed to identify 1) temperature and humidity profiles achieved throughout the growth cycle, 2) management practices and equipment that contributed to observed variation in environmental conditions, and 3) the extent to which environmental variables affected bird welfare. The study involved a total of 2.7 million birds in 114 houses on commercial farms with measurement of a wide range of environmental and bird variables. Much of the variation in broiler health and welfare was associated with the percentage of time a company could maintain house temperature and RH within limits recommended by the breeder company. RH in the first week of life was particularly important to later health, suggesting that better control of humidity might lead to improved welfare. Key management factors affecting bird welfare were those relating to good ventilation and air control such as the type of ventilation, type of drinker, numbers of stockmen, and litter type. Controlling the environment, particularly temperature, humidity, and air and litter quality, is crucial to broiler chicken welfare. This does not mean that stocking density is unimportant, but lowering stocking density on its own, without regard to the environment the birds experience, is not sufficient. Genuine improvements in bird welfare will come from setting standards that combine stocking density, safeguards on the environment, and the genetic makeup of the birds.

Modelling dengue fever risk in the State of Yucatan, Mexico using regional-scale satellite-derived sea surface temperature.

PubMed

Laureano-Rosario, Abdiel E; Garcia-Rejon, Julian E; Gomez-Carro, Salvador; Farfan-Ale, Jose A; Muller-Karger, Frank E

2017-08-01

Accurately predicting vector-borne diseases, such as dengue fever, is essential for communities worldwide. Changes in environmental parameters such as precipitation, air temperature, and humidity are known to influence dengue fever dynamics. Furthermore, previous studies have shown how oceanographic variables, such as El Niño Southern Oscillation (ENSO)-related sea surface temperature from the Pacific Ocean, influences dengue fever in the Americas. However, literature is lacking on the use of regional-scale satellite-derived sea surface temperature (SST) to assess its relationship with dengue fever in coastal areas. Data on confirmed dengue cases, demographics, precipitation, and air temperature were collected. Incidence of weekly dengue cases was examined. Stepwise multiple regression analyses (AIC model selection) were used to assess which environmental variables best explained increased dengue incidence rates. SST, minimum air temperature, precipitation, and humidity substantially explained 42% of the observed variation (r 2 =0.42). Infectious diseases are characterized by the influence of past cases on current cases and results show that previous dengue cases alone explained 89% of the variation. Ordinary least-squares analyses showed a positive trend of 0.20±0.03°C in SST from 2006 to 2015. An important element of this study is to help develop strategic recommendations for public health officials in Mexico by providing a simple early warning capability for dengue incidence. Copyright © 2017 Elsevier B.V. All rights reserved.

Year-class formation of upper St. Lawrence River northern pike

USGS Publications Warehouse

Smith, B.M.; Farrell, J.M.; Underwood, H.B.; Smith, S.J.

2007-01-01

Variables associated with year-class formation in upper St. Lawrence River northern pike Esox lucius were examined to explore population trends. A partial least-squares (PLS) regression model (PLS 1) was used to relate a year-class strength index (YCSI; 1974-1997) to explanatory variables associated with spawning and nursery areas (seasonal water level and temperature and their variability, number of ice days, and last day of ice presence). A second model (PLS 2) incorporated four additional ecological variables: potential predators (abundance of double-crested cormorants Phalacrocorax auritus and yellow perch Perca flavescens), female northern pike biomass (as a measure of stock-recruitment effects), and total phosphorus (productivity). Trends in adult northern pike catch revealed a decline (1981-2005), and year-class strength was positively related to catch per unit effort (CPUE; R2 = 0.58). The YCSI exceeded the 23-year mean in only 2 of the last 10 years. Cyclic patterns in the YCSI time series (along with strong year-classes every 4-6 years) were apparent, as was a dampening effect of amplitude beginning around 1990. The PLS 1 model explained over 50% of variation in both explanatory variables and the dependent variable, YCSI first-order moving-average residuals. Variables retained (N = 10; Wold's statistic ??? 0.8) included negative YCSI associations with high summer water levels, high variability in spring and fall water levels, and variability in fall water temperature. The YCSI exhibited positive associations with high spring, summer, and fall water temperature, variability in spring temperature, and high winter and spring water level. The PLS 2 model led to positive YCSI associations with phosphorus and yellow perch CPUE and a negative correlation with double-crested cormorant abundance. Environmental variables (water level and temperature) are hypothesized to regulate northern pike YCSI cycles, and dampening in YCSI magnitude may be related to a combination of factors, including wetland habitat changes, reduced nutrient loading, and increased predation by double-crested cormorants. ?? Copyright by the American Fisheries Society 2007.

Environmental forcing on the flux of organic-walled dinoflagellate cysts in recent sediments from a subtropical lagoon in the Gulf of California.

PubMed

Cuellar-Martinez, Tomasa; Alonso-Rodríguez, Rosalba; Ruiz-Fernández, Ana Carolina; de Vernal, Anne; Morquecho, Lourdes; Limoges, Audrey; Henry, Maryse; Sanchez-Cabeza, Joan-Albert

2018-04-15

To evaluate the relationship of changes in organic-walled dinoflagellate cyst (dinocyst) fluxes to sediments with environmental variables (air and sea surface temperatures, El Niño conditions, rainfall, and terrigenous index), cyst assemblages were analyzed in a 210 Pb-dated sediment core (~100years) from the pristine San José Lagoon (San José Island, SW Gulf of California). The dinocyst abundance ranged from 3784 to 25,108cystsg -1 and fluxes were of the order of 10 3 -10 4 cystscm -2 yr -1 . Lingulodinium machaerophorum, Polysphaeridium zoharyi and Spiniferites taxa accounted for 96% of the total dinocyst assemblages, and the abundances of these species increased towards the core surface. P. zoharyi fluxes increased from about 1965 onwards. Redundancy analyses, showed that mean minimum air temperature and terrigenous index were the key factors governing dinocyst fluxes. In this study, dinocyst fluxes of dominant taxa had responded to changes in climate-dependent environmental variables during the past ~20years; this may also be the case in other subtropical coastal lagoons. Copyright © 2017 Elsevier B.V. All rights reserved.

Environmental variables associated with vacationers' sun protection at warm weather resorts in North America.

PubMed

Andersen, Peter A; Buller, David B; Walkosz, Barbara J; Scott, Michael D; Beck, Larry; Liu, Xia; Abbott, Allison; Eye, Rachel

2016-04-01

Vacationing at sunny, warm weather locations is a risk factor for excessive solar ultraviolet (UV) radiation exposure and skin cancer. This study examined the association of environmental variables related to UV levels with vacationers' sun protection. Vacationers at 41 summer resorts in 17 states and 1 Canadian Province were interviewed (n=3531) and observed (N=4347) during 2012 and 2013. Clothing coverage, sunglasses, and shade use were observed. Use of sunscreen and sunburns were self-reported. Environmental information was recorded by research staff or acquired from ground stations and the weather service. Temperature was positively associated with sun protection behaviors; however clothing coverage was negatively associated with temperature. Cloud cover was negatively associated with sun protection, with the exception of clothing coverage which was positively associated with it. Elevation showed a mixed pattern of associations with vacationer's sun protection. Latitude of a resort was negatively associated with most sun protection behaviors, such that sun protection increased at more southerly resorts. Similarly, the farther south a vacationer traveled to the resort, the less sun protection they employed. The UV index showed a weak, positive relationship with some sun protection behaviors even when controlling for temperature. Vacationers appeared aware that UV is higher at southern latitudes and may learn UV is intense when living in southern regions. However, many used temperature, an unreliable cue, to judge UV intensity and seemed to adjust clothing for warmth not UV protection. Efforts are needed to help individuals make more accurate sun safety decisions. Copyright © 2016. Published by Elsevier Inc.

Use of glacier river-fed estuary channels by juvenile coho salmon: transitional or rearing habitats?

USGS Publications Warehouse

Hoem Neher, Tammy D.; Rosenberger, Amanda E.; Zimmerman, Christian E.; Walker, Coowe M.; Baird, Steven J.

2014-01-01

Estuaries are among the most productive ecosystems in the world and provide important rearing environments for a variety of fish species. Though generally considered important transitional habitats for smolting salmon, little is known about the role that estuaries serve for rearing and the environmental conditions important for salmon. We illustrate how juvenile coho salmonOncorhynchus kisutch use a glacial river-fed estuary based on examination of spatial and seasonal variability in patterns of abundance, fish size, age structure, condition, and local habitat use. Fish abundance was greater in deeper channels with cooler and less variable temperatures, and these habitats were consistently occupied throughout the season. Variability in channel depth and water temperature was negatively associated with fish abundance. Fish size was negatively related to site distance from the upper extent of the tidal influence, while fish condition did not relate to channel location within the estuary ecotone. Our work demonstrates the potential this glacially-fed estuary serves as both transitional and rearing habitat for juvenile coho salmon during smolt emigration to the ocean, and patterns of fish distribution within the estuary correspond to environmental conditions.

Tolerance adaptation and precipitation changes complicate latitudinal patterns of climate change impacts.

PubMed

Bonebrake, Timothy C; Mastrandrea, Michael D

2010-07-13

Global patterns of biodiversity and comparisons between tropical and temperate ecosystems have pervaded ecology from its inception. However, the urgency in understanding these global patterns has been accentuated by the threat of rapid climate change. We apply an adaptive model of environmental tolerance evolution to global climate data and climate change model projections to examine the relative impacts of climate change on different regions of the globe. Our results project more adverse impacts of warming on tropical populations due to environmental tolerance adaptation to conditions of low interannual variability in temperature. When applied to present variability and future forecasts of precipitation data, the tolerance adaptation model found large reductions in fitness predicted for populations in high-latitude northern hemisphere regions, although some tropical regions had comparable reductions in fitness. We formulated an evolutionary regional climate change index (ERCCI) to additionally incorporate the predicted changes in the interannual variability of temperature and precipitation. Based on this index, we suggest that the magnitude of climate change impacts could be much more heterogeneous across latitude than previously thought. Specifically, tropical regions are likely to be just as affected as temperate regions and, in some regions under some circumstances, possibly more so.

[Dynamics of sap flow density in stems of typical desert shrub Calligonum mongolicum and its responses to environmental variables].

PubMed

Xu, Shi-qin; Ji, Xi-bin; Jin, Bo-wen

2016-02-01

Independent measurements of stem sap flow in stems of Calligonum mongolicum and environmental variables using commercial sap flow gauges and a micrometeorological monitoring system, respectively, were made to simulate the variation of sap flow density in the middle range of Hexi Corridor, Northwest China during June to September, 2014. The results showed that the diurnal process of sap flow density in C. mongolicum showed a broad unimodal change, and the maximum sap flow density reached about 30 minutes after the maximum of photosynthetically active radiation (PAR) , while about 120 minutes before the maximum of temperature and vapor pressure deficit (VPD). During the studying period, sap flow density closely related with atmosphere evapor-transpiration demand, and mainly affected by PAR, temperature and VPD. The model was developed which directly linked the sap flow density with climatic variables, and good correlation between measured and simulated sap flow density was observed in different climate conditions. The accuracy of simulation was significantly improved if the time-lag effect was taken into consideration, while this model underestimated low and nighttime sap flow densities, which was probably caused by plant physiological characteristics.

Avian predator buffers against variability in marine habitats with flexible foraging behavior

USGS Publications Warehouse

Schoen, Sarah K.; Piatt, John F.; Arimitsu, Mayumi L.; Heflin, Brielle; Madison, Erica N.; Drew, Gary S.; Renner, Martin; Rojek, Nora A.; Douglas, David C.; DeGange, Anthony R.

2018-01-01

How well seabirds compensate for variability in prey abundance and composition near their breeding colonies influences their distribution and reproductive success. We used tufted puffins (Fratercula cirrhata) as forage fish samplers to study marine food webs from the western Aleutian Islands (53°N, 173°E) to Kodiak Island (57°N, 153°W), Alaska, during August 2012–2014. Around each colony we obtained data on: environmental characteristics (sea surface temperature and salinity, seafloor depth and slope, tidal range, and chlorophyll-a), relative forage fish biomass (hydroacoustic backscatter), and seabird community composition and density at-sea. On colonies, we collected puffin chick-meals to characterize forage communities and determine meal energy density, and measured chicks to obtain a body condition index. There were distinct environmental gradients from west to east, and environmental variables differed by ecoregions: the (1) Western-Central Aleutians, (2) Eastern Aleutians, and, (3) Alaska Peninsula. Forage fish biomass, species richness, and community composition all differed markedly between ecoregions. Forage biomass was strongly correlated with environmental gradients, and environmental gradients and forage biomass accounted for ~ 50% of the variability in at-sea density of tufted puffins and all seabird taxa combined. Despite the local and regional variability in marine environments and forage, the mean biomass of prey delivered to puffin chicks did not differ significantly between ecoregions, nor did chick condition or puffin density at-sea. We conclude that puffins can adjust their foraging behavior to produce healthy chicks across a wide range of environmental conditions. This extraordinary flexibility enables their overall success and wide distribution across the North Pacific Ocean.

Status of vulnerable Cystoseira populations along the Italian infralittoral fringe, and relationships with environmental and anthropogenic variables.

PubMed

Mancuso, F P; Strain, E M A; Piccioni, E; De Clerck, O; Sarà, G; Airoldi, L

2018-04-01

We analyzed the occurrence and status of infralittoral fringe populations of Cystoseira spp. (Fucales) at thirteen rocky sites around the Italian coastline, and explored the relationships with relevant environmental and anthropogenic variables. We found Cystoseira populations at 11 sites: most were scattered and comprised monospecific stands of C. compressa, and only 6 sites also supported sparse specimens of either C. amentacea var. stricta or C. brachycarpa. Coastal human population density, Chlorophyll a seawater concentrations, sea surface temperature, annual range of sea surface temperature and wave fetch explained most of the variation of the status of C. compressa. We hypothesize a generally unhealthy state of the Italian Cystoseira infralittoral fringe populations and identify multiple co-occurring anthropogenic stressors as the likely drivers of these poor conditions. Extensive baseline monitoring is needed to describe how Cystoseira populations are changing, and implement a management framework for the conservation of these valuable but vulnerable habitats. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multimodel inference to quantify the relative importance of abiotic factors in the population dynamics of marine zooplankton

NASA Astrophysics Data System (ADS)

Everaert, Gert; Deschutter, Yana; De Troch, Marleen; Janssen, Colin R.; De Schamphelaere, Karel

2018-05-01

The effect of multiple stressors on marine ecosystems remains poorly understood and most of the knowledge available is related to phytoplankton. To partly address this knowledge gap, we tested if combining multimodel inference with generalized additive modelling could quantify the relative contribution of environmental variables on the population dynamics of a zooplankton species in the Belgian part of the North Sea. Hence, we have quantified the relative contribution of oceanographic variables (e.g. water temperature, salinity, nutrient concentrations, and chlorophyll a concentrations) and anthropogenic chemicals (i.e. polychlorinated biphenyls) to the density of Acartia clausi. We found that models with water temperature and chlorophyll a concentration explained ca. 73% of the population density of the marine copepod. Multimodel inference in combination with regression-based models are a generic way to disentangle and quantify multiple stressor-induced changes in marine ecosystems. Future-oriented simulations of copepod densities suggested increased copepod densities under predicted environmental changes.

Biological and environmental rhythms in (dark) deep-sea hydrothermal ecosystems

NASA Astrophysics Data System (ADS)

Cuvelier, Daphne; Legendre, Pierre; Laës-Huon, Agathe; Sarradin, Pierre-Marie; Sarrazin, Jozée

2017-06-01

During 2011, two deep-sea observatories focusing on hydrothermal vent ecology were up and running in the Atlantic (Eiffel Tower, Lucky Strike vent field) and the Northeast Pacific Ocean (NEP) (Grotto, Main Endeavour Field). Both ecological modules recorded imagery and environmental variables jointly for a time span of 23 days (7-30 October 2011) and environmental variables for up to 9 months (October 2011-June 2012). Community dynamics were assessed based on imagery analysis and rhythms in temporal variation for both fauna and environment were revealed. Tidal rhythms were found to be at play in the two settings and were most visible in temperature and tubeworm appearances (at NEP). A ˜ 6 h lag in tidal rhythm occurrence was observed between Pacific and Atlantic hydrothermal vents, which corresponds to the geographical distance and time delay between the two sites.

A temperature rise reduces trial-to-trial variability of locust auditory neuron responses.

PubMed

Eberhard, Monika J B; Schleimer, Jan-Hendrik; Schreiber, Susanne; Ronacher, Bernhard

2015-09-01

The neurophysiology of ectothermic animals, such as insects, is affected by environmental temperature, as their body temperature fluctuates with ambient conditions. Changes in temperature alter properties of neurons and, consequently, have an impact on the processing of information. Nevertheless, nervous system function is often maintained over a broad temperature range, exhibiting a surprising robustness to variations in temperature. A special problem arises for acoustically communicating insects, as in these animals mate recognition and mate localization typically rely on the decoding of fast amplitude modulations in calling and courtship songs. In the auditory periphery, however, temporal resolution is constrained by intrinsic neuronal noise. Such noise predominantly arises from the stochasticity of ion channel gating and potentially impairs the processing of sensory signals. On the basis of intracellular recordings of locust auditory neurons, we show that intrinsic neuronal variability on the level of spikes is reduced with increasing temperature. We use a detailed mathematical model including stochastic ion channel gating to shed light on the underlying biophysical mechanisms in auditory receptor neurons: because of a redistribution of channel-induced current noise toward higher frequencies and specifics of the temperature dependence of the membrane impedance, membrane potential noise is indeed reduced at higher temperatures. This finding holds under generic conditions and physiologically plausible assumptions on the temperature dependence of the channels' kinetics and peak conductances. We demonstrate that the identified mechanism also can explain the experimentally observed reduction of spike timing variability at higher temperatures. Copyright © 2015 the American Physiological Society.

Elevated temperature alters the lunar timing of Planulation in the brooding coral Pocillopora damicornis.

PubMed

Crowder, Camerron M; Liang, Wei-Lo; Weis, Virginia M; Fan, Tung-Yung

2014-01-01

Reproductive timing in corals is associated with environmental variables including temperature, lunar periodicity, and seasonality. Although it is clear that these variables are interrelated, it remains unknown if one variable in particular acts as the proximate signaler for gamete and or larval release. Furthermore, in an era of global warming, the degree to which increases in ocean temperatures will disrupt normal reproductive patterns in corals remains unknown. Pocillopora damicornis, a brooding coral widely distributed in the Indo-Pacific, has been the subject of multiple reproductive ecology studies that show correlations between temperature, lunar periodicity, and reproductive timing. However, to date, no study has empirically measured changes in reproductive timing associated with increased seawater temperature. In this study, the effect of increased seawater temperature on the timing of planula release was examined during the lunar cycles of March and June 2012. Twelve brooding corals were removed from Hobihu reef in Nanwan Bay, southern Taiwan and placed in 23 and 28°C controlled temperature treatment tanks. For both seasons, the timing of planulation was found to be plastic, with the high temperature treatment resulting in significantly earlier peaks of planula release compared to the low temperature treatment. This suggests that temperature alone can influence the timing of larval release in Pocillopora damicornis in Nanwan Bay. Therefore, it is expected that continued increases in ocean temperature will result in earlier timing of reproductive events in corals, which may lead to either variations in reproductive success or phenotypic acclimatization.

Elevated Temperature Alters the Lunar Timing of Planulation in the Brooding Coral Pocillopora damicornis

PubMed Central

Crowder, Camerron M.; Liang, Wei-Lo; Weis, Virginia M.; Fan, Tung-Yung

2014-01-01

Reproductive timing in corals is associated with environmental variables including temperature, lunar periodicity, and seasonality. Although it is clear that these variables are interrelated, it remains unknown if one variable in particular acts as the proximate signaler for gamete and or larval release. Furthermore, in an era of global warming, the degree to which increases in ocean temperatures will disrupt normal reproductive patterns in corals remains unknown. Pocillopora damicornis, a brooding coral widely distributed in the Indo-Pacific, has been the subject of multiple reproductive ecology studies that show correlations between temperature, lunar periodicity, and reproductive timing. However, to date, no study has empirically measured changes in reproductive timing associated with increased seawater temperature. In this study, the effect of increased seawater temperature on the timing of planula release was examined during the lunar cycles of March and June 2012. Twelve brooding corals were removed from Hobihu reef in Nanwan Bay, southern Taiwan and placed in 23 and 28°C controlled temperature treatment tanks. For both seasons, the timing of planulation was found to be plastic, with the high temperature treatment resulting in significantly earlier peaks of planula release compared to the low temperature treatment. This suggests that temperature alone can influence the timing of larval release in Pocillopora damicornis in Nanwan Bay. Therefore, it is expected that continued increases in ocean temperature will result in earlier timing of reproductive events in corals, which may lead to either variations in reproductive success or phenotypic acclimatization. PMID:25329546

A temperature rise reduces trial-to-trial variability of locust auditory neuron responses

PubMed Central

Schleimer, Jan-Hendrik; Schreiber, Susanne; Ronacher, Bernhard

2015-01-01

The neurophysiology of ectothermic animals, such as insects, is affected by environmental temperature, as their body temperature fluctuates with ambient conditions. Changes in temperature alter properties of neurons and, consequently, have an impact on the processing of information. Nevertheless, nervous system function is often maintained over a broad temperature range, exhibiting a surprising robustness to variations in temperature. A special problem arises for acoustically communicating insects, as in these animals mate recognition and mate localization typically rely on the decoding of fast amplitude modulations in calling and courtship songs. In the auditory periphery, however, temporal resolution is constrained by intrinsic neuronal noise. Such noise predominantly arises from the stochasticity of ion channel gating and potentially impairs the processing of sensory signals. On the basis of intracellular recordings of locust auditory neurons, we show that intrinsic neuronal variability on the level of spikes is reduced with increasing temperature. We use a detailed mathematical model including stochastic ion channel gating to shed light on the underlying biophysical mechanisms in auditory receptor neurons: because of a redistribution of channel-induced current noise toward higher frequencies and specifics of the temperature dependence of the membrane impedance, membrane potential noise is indeed reduced at higher temperatures. This finding holds under generic conditions and physiologically plausible assumptions on the temperature dependence of the channels' kinetics and peak conductances. We demonstrate that the identified mechanism also can explain the experimentally observed reduction of spike timing variability at higher temperatures. PMID:26041833

Climate Variability, Social and Environmental Factors, and Ross River Virus Transmission: Research Development and Future Research Needs

PubMed Central

Tong, Shilu; Dale, Pat; Nicholls, Neville; Mackenzie, John S.; Wolff, Rodney; McMichael, Anthony J.

2008-01-01

Background Arbovirus diseases have emerged as a global public health concern. However, the impact of climatic, social, and environmental variability on the transmission of arbovirus diseases remains to be determined. Objective Our goal for this study was to provide an overview of research development and future research directions about the interrelationship between climate variability, social and environmental factors, and the transmission of Ross River virus (RRV), the most common and widespread arbovirus disease in Australia. Methods We conducted a systematic literature search on climatic, social, and environmental factors and RRV disease. Potentially relevant studies were identified from a series of electronic searches. Results The body of evidence revealed that the transmission cycles of RRV disease appear to be sensitive to climate and tidal variability. Rainfall, temperature, and high tides were among major determinants of the transmission of RRV disease at the macro level. However, the nature and magnitude of the interrelationship between climate variability, mosquito density, and the transmission of RRV disease varied with geographic area and socioenvironmental condition. Projected anthropogenic global climatic change may result in an increase in RRV infections, and the key determinants of RRV transmission we have identified here may be useful in the development of an early warning system. Conclusions The analysis indicates that there is a complex relationship between climate variability, social and environmental factors, and RRV transmission. Different strategies may be needed for the control and prevention of RRV disease at different levels. These research findings could be used as an additional tool to support decision making in disease control/surveillance and risk management. PMID:19079707

Effects of changing environmental conditions on synthetic aperture radar backscattering coefficient, scattering mechanisms, and class separability in a forest area

NASA Astrophysics Data System (ADS)

Mahdavi, Sahel; Maghsoudi, Yasser; Amani, Meisam

2017-07-01

Environmental conditions have considerable effects on synthetic aperture radar (SAR) imagery. Therefore, assessing these effects is important for obtaining accurate and reliable results. In this study, three series of RADARSAT-2 SAR images were evaluated. In each of these series, the sensor configuration was fixed, but the environmental conditions differed. The effects of variable environmental conditions were also investigated on co- and cross-polarized backscattering coefficients, Freeman-Durden scattering contributions, and the pedestal height in different classes of a forest area in Ottawa, Ontario. It was observed that the backscattering coefficient of wet snow was up to 2 dB more than that of dry snow. The absence of snow also caused a decrease of up to 3 dB in the surface scattering of ground and up to 5 dB in that of trees. In addition, the backscatter coefficients of ground vegetation, hardwood species, and softwood species were more similar at temperatures below 0°C than those at temperatures above 0°C. Moreover, the pedestal height was generally greater at temperatures above 0°C than at temperatures below 0°C. Finally, the highest class separability was observed when the temperature was at or above 0°C and there was no snow on the ground or trees.

The Effects of Temperature and Hydrostatic Pressure on Metal Toxicity: Insights into Toxicity in the Deep Sea.

PubMed

Brown, Alastair; Thatje, Sven; Hauton, Chris

2017-09-05

Mineral prospecting in the deep sea is increasing, promoting concern regarding potential ecotoxicological impacts on deep-sea fauna. Technological difficulties in assessing toxicity in deep-sea species has promoted interest in developing shallow-water ecotoxicological proxy species. However, it is unclear how the low temperature and high hydrostatic pressure prevalent in the deep sea affect toxicity, and whether adaptation to deep-sea environmental conditions moderates any effects of these factors. To address these uncertainties we assessed the effects of temperature and hydrostatic pressure on lethal and sublethal (respiration rate, antioxidant enzyme activity) toxicity in acute (96 h) copper and cadmium exposures, using the shallow-water ecophysiological model organism Palaemon varians. Low temperature reduced toxicity in both metals, but reduced cadmium toxicity significantly more. In contrast, elevated hydrostatic pressure increased copper toxicity, but did not affect cadmium toxicity. The synergistic interaction between copper and cadmium was not affected by low temperature, but high hydrostatic pressure significantly enhanced the synergism. Differential environmental effects on toxicity suggest different mechanisms of action for copper and cadmium, and highlight that mechanistic understanding of toxicity is fundamental to predicting environmental effects on toxicity. Although results infer that sensitivity to toxicants differs across biogeographic ranges, shallow-water species may be suitable ecotoxicological proxies for deep-sea species, dependent on adaptation to habitats with similar environmental variability.

The effect of local environmental variables on the helminth parasite communities of the pointedbelly frog Leptodactylus podicipinus from ponds in the Pantanal wetlands.

PubMed

Campião, Karla Magalhães; Delatorre, Milena; Rodrigues, Rozangela Batista; da Silva, Reinaldo José; Ferreira, Vanda Lúcia

2012-04-01

Understanding the patterns of species distribution and abundance has been at the core of ecology. In general, these patterns are determined by species dispersion as well as by abiotic and biotic environmental conditions. Similarly, host-parasite relations and the structure of parasite assemblages are also shaped by environmental conditions and landscape composition. Herein, we assessed the influence of environmental variables and parasite species dispersion on the structure of helminth parasites communities in the frog Leptodactylus podicipinus. We sampled 10 ponds and recorded area, depth, altitude, pH, dissolved oxygen, salinity, temperature, and extent of soil, water, and vegetation cover as well as the distances between the ponds. We collected 121 frogs and found 9 helminth taxa; 2 of them were core species (prevalence higher than 50%), which contributed to the relatively high similarity observed among the ponds. Most of the helminths showed some variation in the frequencies of occurrence among communities from different ponds. The change in species composition among ponds was explained by the environmental variables but not by the distance between the ponds. Moreover, the results indicated that local processes (variation in environmental conditions) were more important than the regional processes (species distribution) in determining the structure of parasite communities. The variation in helminth communities among ponds in response to moderate differences in pond environmental characteristics points to the potential of helminth species as indicators of environmental conditions.

Present and future ecological niche modeling of garter snake species from the Trans-Mexican Volcanic Belt

PubMed Central

García-Vázquez, Uri; D’Addario, Maristella

2018-01-01

Land use and climate change are affecting the abundance and distribution of species. The Trans-Mexican Volcanic Belt (TMVB) is a very diverse region due to geological history, geographic position, and climate. It is also one of the most disturbed regions in Mexico. Reptiles are particularly sensitive to environmental changes due to their low dispersal capacity and thermal ecology. In this study, we define the important environmental variables (considering climate, topography, and land use) and potential distribution (present and future) of the five Thamnophis species present in TMVB. To do so, we used the maximum entropy modeling software (MAXENT). First, we modeled to select the most important variables to explain the distribution of each species, then we modeled again using only the most important variables and projected these models to the future considering a middle-moderate climate change scenario (rcp45), and land use and vegetation variables for the year 2050 (generated according to land use changes that occurred between years 2002 and 2011). Arid vegetation had an important negative effect on habitat suitability for all species, and minimum temperature of the coldest month was important for four of the five species. Thamnophis cyrtopsis was the species with the lowest tolerance to minimum temperatures. The maximum temperature of the warmest month was important for T. scalaris and T. cyrtopsis. Low percentages of agriculture were positive for T. eques and T. melanogaster but, at higher values, agriculture had a negative effect on habitat suitability for both species. Elevation was the most important variable to explain T. eques and T. melanogaster potential distribution while distance to Abies forests was the most important variable for T. scalaris and T. scaliger. All species had a high proportion of their potential distribution in the TMVB. However, according to our models, all Thamnophis species will experience reductions in their potential distribution in this region. T. scalaris will suffer the biggest reduction because this species is limited by high temperatures and will not be able to shift its distribution upward, as it is already present in the highest elevations of the TMVB. PMID:29666767

Seasonal, daily activity, and habitat use by three sympatric pit vipers (Serpentes, Viperidae) from southern Brazil.

PubMed

Rocha, Marcelo C; Hartmann, Paulo A; Winck, Gisele R; Cechin, Sonia Z

2014-04-25

Viperid snakes are widely distributed in the South America and the greater distribution range of the family is found at the Crotalinae subfamily. Despite the abundance of this snakes along their geographic distribution, some ecological aspects remain unknown, principally at subtropical areas. In the present study, we evaluated the activity (daily and seasonal) and the use of the habitat by Bothrops diporus, B. jararaca and B. jararacussu, in an Atlantic Forest area at southern Brazil. We observed higher incidence of viperid snakes during the months with higher temperatures, while no snakes were found during the months with lower temperatures. The data suggest the minimum temperature as environmental variable with the greatest influence on the seasonal activity of this species. Considering the daily activity, we observed a tendency of snakes to avoid the warmest hours. Bothrops jararacussu tend to avoid open areas, being registered only inside and at the edges of the forest. We compared our results with previous studies realized at tropical areas and we suggest the observed seasonal activity as an evolutive response, despite the influence of the different environmental variables, according to the occurence region.

Plastic and evolutionary responses of plankton to environmental change are influenced by drift in ocean currents

NASA Astrophysics Data System (ADS)

Doblin, M.; van Sebille, E.

2016-02-01

The analytical framework for understanding fluctuations in ocean habitats has typically involved a Eulerian view. However, for marine microbes, this framework does not take into account their transport in dynamic seascapes, implying that our current view of change for these critical organisms may be inaccurate. Using a modelling approach, we show that generations of upper ocean microbes experience along-trajectory temperature variability up to 10°C greater than seasonal fluctuations estimated in a static frame, and that this variability depends strongly on location. These findings demonstrate that drift in ocean currents contributes to environmental fluctuation experienced by microbes and suggests that microbial populations may be adapted to upstream rather than local conditions. In an empirical test, we demonstrate that microbes in a warm, poleward flowing western boundary current (East Australian Current) have a different thermal response curve to microbes in coastal water at the same latitude (p < 0.05). Our findings suggest that advection has the capacity to influence microbial community assemblies such that water masses with relatively small thermal fluctuations select for thermal specialists, and communities with broad temperature performance curves are found in locations where ocean currents are strong or along-trajectory temperature variation is high.

Environmental and biological characteristics of Atlantic bluefin tuna and albacore spawning habitats based on their egg distributions

NASA Astrophysics Data System (ADS)

Reglero, Patricia; Santos, Maria; Balbín, Rosa; Laíz-Carrión, Raul; Alvarez-Berastegui, Diego; Ciannelli, Lorenzo; Jiménez, Elisa; Alemany, Francisco

2017-06-01

Tuna spawning habitats are traditionally characterized using data sets of larvae or gonads from mature adults and concurrent environmental variables. Data on egg distributions have never previously been used since molecular analyses are mandatory to identify tuna eggs to species level. However, in this study we use molecularly derived egg distribution data, in addition to larval data, to characterize hydrographic and biological drivers of the spatial distribution of eggs and larvae of bluefin Thunnus thynnus and albacore tuna Thunnus alalunga in the Balearic Sea, a main spawning area of these species in the Mediterranean. The effects of the hydrography, characterized by salinity, temperature and geostrophic velocity, on the spatial distributions of the eggs and larvae are investigated. Three biological variables are used to describe the productivity in the area: chlorophyll a in the mixed layer, chlorophyll a in the deep chlorophyll maximum and mesozooplankton biomass in the mixed layer. Our results point to the importance of salinity fronts and temperatures above a minimum threshold in shaping the egg and larval distribution of both species. The spatial distribution of the biotic variables was very scattered, and they did not emerge as significant variables in the presence-absence models. However, they became significant when modeling egg and larval abundances. The lack of correlation between the three biotic variables challenges the use of chlorophyll a to describe trophic scenarios for the larvae and suggests that the spatial distribution of resources is not persistent in time. The different patterns in relation to biotic variables across species and stages found in this and other studies indicate a still elusive understanding of the link between trophic levels involving tuna early larval stages. Our ability to improve short-term forecasting and long-term predictions of climate effects on the egg and larval distributions is discussed based on the consistency of the environmentally driven spatial patterns for the two species.

Modeling the role of environmental variables on the population dynamics of the malaria vector Anopheles gambiae sensu stricto

PubMed Central

2012-01-01

Background The impact of weather and climate on malaria transmission has attracted considerable attention in recent years, yet uncertainties around future disease trends under climate change remain. Mathematical models provide powerful tools for addressing such questions and understanding the implications for interventions and eradication strategies, but these require realistic modeling of the vector population dynamics and its response to environmental variables. Methods Published and unpublished field and experimental data are used to develop new formulations for modeling the relationships between key aspects of vector ecology and environmental variables. These relationships are integrated within a validated deterministic model of Anopheles gambiae s.s. population dynamics to provide a valuable tool for understanding vector response to biotic and abiotic variables. Results A novel, parsimonious framework for assessing the effects of rainfall, cloudiness, wind speed, desiccation, temperature, relative humidity and density-dependence on vector abundance is developed, allowing ease of construction, analysis, and integration into malaria transmission models. Model validation shows good agreement with longitudinal vector abundance data from Tanzania, suggesting that recent malaria reductions in certain areas of Africa could be due to changing environmental conditions affecting vector populations. Conclusions Mathematical models provide a powerful, explanatory means of understanding the role of environmental variables on mosquito populations and hence for predicting future malaria transmission under global change. The framework developed provides a valuable advance in this respect, but also highlights key research gaps that need to be resolved if we are to better understand future malaria risk in vulnerable communities. PMID:22877154

Global variation of carbon use efficiency in terrestrial ecosystems

NASA Astrophysics Data System (ADS)

Tang, Xiaolu; Carvalhais, Nuno; Moura, Catarina; Reichstein, Markus

2017-04-01

Carbon use efficiency (CUE), defined as the ratio between net primary production (NPP) and gross primary production (GPP), is an emergent property of vegetation that describes its effectiveness in storing carbon (C) and is of significance for understanding C biosphere-atmosphere exchange dynamics. A constant CUE value of 0.5 has been widely used in terrestrial C-cycle models, such as the Carnegie-Ames-Stanford-Approach model, or the Marine Biological Laboratory/Soil Plant-Atmosphere Canopy Model, for regional or global modeling purposes. However, increasing evidence argues that CUE is not constant, but varies with ecosystem types, site fertility, climate, site management and forest age. Hence, the assumption of a constant CUE of 0.5 can produce great uncertainty in estimating global carbon dynamics between terrestrial ecosystems and the atmosphere. Here, in order to analyze the global variations in CUE and understand how CUE varies with environmental variables, a global database was constructed based on published data for crops, forests, grasslands, wetlands and tundra ecosystems. In addition to CUE data, were also collected: GPP and NPP; site variables (e.g. climate zone, site management and plant function type); climate variables (e.g. temperature and precipitation); additional carbon fluxes (e.g. soil respiration, autotrophic respiration and heterotrophic respiration); and carbon pools (e.g. stem, leaf and root biomass). Different climate metrics were derived to diagnose seasonal temperature (mean annual temperature, MAT, and maximum temperature, Tmax) and water availability proxies (mean annual precipitation, MAP, and Palmer Drought Severity Index), in order to improve the local representation of environmental variables. Additionally were also included vegetation phenology dynamics as observed by different vegetation indices from the MODIS satellite. The mean CUE of all terrestrial ecosystems was 0.45, 10% lower than the previous assumed constant CUE of 0.50. CUE varied significantly between sites - from 0.13 to 0.93 - and between ecosystem types, ranging between 0.41 and 0.60, decreasing from wetlands, to tundra, to croplands, to grasslands until the lower CUE found on average for forested ecosystems. Our analysis shows that ecosystem type was the most important predictor of CUE in terrestrial ecosystems, immediately followed by Tmax; MAT and management practices. For crop, forest and wetland ecosystems CUE varied with climate zones and a strong linear negative correlation was found between CUE and MAT and MAP for grassland ecosystems. Overall, the interaction between different environmental variables showed significant effects on CUE for all ecosystem types. Our results challenge the consideration of a constant value of 0.5 for modeling global purposes, and argue for a deeper understanding of environmental controls on CUE for different ecosystem types.

Predictability and environmental drivers of chlorophyll fluctuations vary across different time scales and regions of the North Sea

NASA Astrophysics Data System (ADS)

Blauw, Anouk N.; Benincà, Elisa; Laane, Remi W. P. M.; Greenwood, Naomi; Huisman, Jef

2018-02-01

Phytoplankton concentrations display strong temporal variability at different time scales. Recent advances in automated moorings enable detailed investigation of this variability. In this study, we analyzed phytoplankton fluctuations at four automated mooring stations in the North Sea, which measured phytoplankton abundance (chlorophyll) and several environmental variables at a temporal resolution of 12-30 min for two to nine years. The stations differed in tidal range, water depth and freshwater influence. This allowed comparison of the predictability and environmental drivers of phytoplankton variability across different time scales and geographical regions. We analyzed the time series using wavelet analysis, cross correlations and generalized additive models to quantify the response of chlorophyll fluorescence to various environmental variables (tidal and meteorological variables, salinity, suspended particulate matter, nitrate and sea surface temperature). Hour-to-hour and day-to-day fluctuations in chlorophyll fluorescence were substantial, and mainly driven by sinking and vertical mixing of phytoplankton cells, horizontal transport of different water masses, and non-photochemical quenching of the fluorescence signal. At the macro-tidal stations, these short-term phytoplankton fluctuations were strongly driven by the tides. Along the Dutch coast, variation in salinity associated with the freshwater influence of the river Rhine played an important role, while in the central North Sea variation in weather conditions was a major determinant of phytoplankton variability. At time scales of weeks to months, solar irradiance, nutrient conditions and thermal stratification were the dominant drivers of changes in chlorophyll concentrations. These results show that the dominant drivers of phytoplankton fluctuations differ across marine environments and time scales. Moreover, our findings show that phytoplankton variability on hourly to daily time scales should not be dismissed as environmental noise, but is related to vertical and horizontal particle transport driven by winds and tides. Quantification of these transport processes contributes to an improved predictability of marine phytoplankton concentrations.

The impact of background radiation, illumination and temperature on EMF-induced changes of aqua medium properties.

PubMed

Naira, Baghdasaryan; Yerazik, Mikayelyan; Anna, Nikoghosyan; Sinerik, Ayrapetyan

2013-09-01

The effects of extremely low frequency electromagnetic field (ELF EMF) on physicochemical properties of physiological solution at different environmental media were studied. The existence of frequency "windows" at 4 and 8 Hz frequencies of ELF EMF having effects on heat fusion period, hydrogen peroxide (H2O2) formation and oxygen (O2) content of water solution and different dependency on temperature, background radiation and illumination was shown. Obtained data allow us to suggest that EMF-induced effect on water physicochemical properties depends on abovementioned environmental factors. As cell bathing medium is a target for biological effects of ELF EMF, the variability of experimental data on biological effects of EMF, obtained in different laboratories, can be explained by different environmental conditions of experiments, which very often are not considered adequately.

Skin Temperature Measurement Using Contact Thermometry: A Systematic Review of Setup Variables and Their Effects on Measured Values

PubMed Central

MacRae, Braid A.; Annaheim, Simon; Spengler, Christina M.; Rossi, René M.

2018-01-01

Background: Skin temperature (Tskin) is commonly measured using Tskin sensors affixed directly to the skin surface, although the influence of setup variables on the measured outcome requires clarification. Objectives: The two distinct objectives of this systematic review were (1) to examine measurements from contact Tskin sensors considering equilibrium temperature and temperature disturbance, sensor attachments, pressure, environmental temperature, and sensor type, and (2) to characterise the contact Tskin sensors used, conditions of use, and subsequent reporting in studies investigating sports, exercise, and other physical activity. Data sources and study selection: For the measurement comparison objective, Ovid Medline and Scopus were used (1960 to July 2016) and studies comparing contact Tskin sensor measurements in vivo or using appropriate physical models were included. For the survey of use, Ovid Medline was used (2011 to July 2016) and studies using contact temperature sensors for the measurement of human Tskin in vivo during sport, exercise, and other physical activity were included. Study appraisal and synthesis methods: For measurement comparisons, assessments of risk of bias were made according to an adapted version of the Cochrane Collaboration's risk of bias tool. Comparisons of temperature measurements were expressed, where possible, as mean difference and 95% limits of agreement (LoA). Meta-analyses were not performed due to the lack of a common reference condition. For the survey of use, extracted information was summarised in text and tabular form. Results: For measurement comparisons, 21 studies were included. Results from these studies indicated minor (<0.5°C) to practically meaningful (>0.5°C) measurement bias within the subgroups of attachment type, applied pressure, environmental conditions, and sensor type. The 95% LoA were often within 1.0°C for in vivo studies and 0.5°C for physical models. For the survey of use, 172 studies were included. Details about Tskin sensor setup were often poorly reported and, from those reporting setup information, it was evident that setups widely varied in terms of type of sensors, attachments, and locations used. Conclusions: Setup variables and conditions of use can influence the measured temperature from contact Tskin sensors and thus key setup variables need to be appropriately considered and consistently reported. PMID:29441024

Skin Temperature Measurement Using Contact Thermometry: A Systematic Review of Setup Variables and Their Effects on Measured Values.

PubMed

MacRae, Braid A; Annaheim, Simon; Spengler, Christina M; Rossi, René M

2018-01-01

Background: Skin temperature ( T skin ) is commonly measured using T skin sensors affixed directly to the skin surface, although the influence of setup variables on the measured outcome requires clarification. Objectives: The two distinct objectives of this systematic review were (1) to examine measurements from contact T skin sensors considering equilibrium temperature and temperature disturbance, sensor attachments, pressure, environmental temperature, and sensor type, and (2) to characterise the contact T skin sensors used, conditions of use, and subsequent reporting in studies investigating sports, exercise, and other physical activity. Data sources and study selection: For the measurement comparison objective, Ovid Medline and Scopus were used (1960 to July 2016) and studies comparing contact T skin sensor measurements in vivo or using appropriate physical models were included. For the survey of use, Ovid Medline was used (2011 to July 2016) and studies using contact temperature sensors for the measurement of human T skin in vivo during sport, exercise, and other physical activity were included. Study appraisal and synthesis methods: For measurement comparisons, assessments of risk of bias were made according to an adapted version of the Cochrane Collaboration's risk of bias tool. Comparisons of temperature measurements were expressed, where possible, as mean difference and 95% limits of agreement (LoA). Meta-analyses were not performed due to the lack of a common reference condition. For the survey of use, extracted information was summarised in text and tabular form. Results: For measurement comparisons, 21 studies were included. Results from these studies indicated minor (<0.5°C) to practically meaningful (>0.5°C) measurement bias within the subgroups of attachment type, applied pressure, environmental conditions, and sensor type. The 95% LoA were often within 1.0°C for in vivo studies and 0.5°C for physical models. For the survey of use, 172 studies were included. Details about T skin sensor setup were often poorly reported and, from those reporting setup information, it was evident that setups widely varied in terms of type of sensors, attachments, and locations used. Conclusions: Setup variables and conditions of use can influence the measured temperature from contact T skin sensors and thus key setup variables need to be appropriately considered and consistently reported.

Transcriptomics of environmental acclimatization and survival in wild adult Pacific sockeye salmon (Oncorhynchus nerka) during spawning migration.

PubMed

Evans, Tyler G; Hammill, Edd; Kaukinen, Karia; Schulze, Angela D; Patterson, David A; English, Karl K; Curtis, Janelle M R; Miller, Kristina M

2011-11-01

Environmental shifts accompanying salmon spawning migrations from ocean feeding grounds to natal freshwater streams can be severe, with the underlying stress often cited as a cause of increased mortality. Here, a salmonid microarray was used to characterize changes in gene expression occurring between ocean and river habitats in gill and liver tissues of wild migrating sockeye salmon (Oncorhynchus nerka Walbaum) returning to spawn in the Fraser River, British Columbia, Canada. Expression profiles indicate that the transcriptome of migrating salmon is strongly affected by shifting abiotic and biotic conditions encountered along migration routes. Conspicuous shifts in gene expression associated with changing salinity, temperature, pathogen exposure and dissolved oxygen indicate that these environmental variables most strongly impact physiology during spawning migrations. Notably, transcriptional changes related to osmoregulation were largely preparatory and occurred well before salmon encountered freshwater. In the river environment, differential expression of genes linked with elevated temperatures indicated that thermal regimes within the Fraser River are approaching tolerance limits for adult salmon. To empirically correlate gene expression with survival, biopsy sampling of gill tissue and transcriptomic profiling were combined with telemetry. Many genes correlated with environmental variables were differentially expressed between premature mortalities and successful migrants. Parametric survival analyses demonstrated a broad-scale transcriptional regulator, cofactor required for Sp1 transcriptional activation (CRSP), to be significantly predictive of survival. As the environmental characteristics of salmon habitats continue to change, establishing how current environmental conditions influence salmon physiology under natural conditions is critical to conserving this ecologically and economically important fish species. © 2011 Blackwell Publishing Ltd.

Chemochromic detector for sensing gas leakage and process for producing the same

NASA Technical Reports Server (NTRS)

Roberson, Luke B. (Inventor); Williams, Martha K. (Inventor); Captain, Janine E. (Inventor); Smith, Trent M. (Inventor); Tate, LaNetra Clayton (Inventor)

2012-01-01

A chemochromic sensor for detecting a combustible gas, such as hydrogen, includes a chemochromic pigment mechanically mixed with a polymer and formed into a rigid or pliable material. In a preferred embodiment, the chemochromic detector includes aerogel material. The detector is robust and easily modifiable for a variety of applications and environmental conditions, such as atmospheres of inert gas, hydrogen gas, or mixtures of gases, or in environments that have variable temperature, including high temperatures such as above 100.degree. C. and low temperatures such as below -196.degree. C.

Interactions between chemical and climate stressors: A role for mechanistic toxicology in assessing climate change risks

EPA Science Inventory

Incorporation of global climate change (GCC) effects into regulatory assessments of chemical risk and injury requires an integrated examination of both chemical and non-chemical stressors. Environmental variables altered by GCC, such as temperature, precipitation, salinity and pH...

Microclimate in Forest Ecosystem and Landscape Ecology

Treesearch

Jiquan Chen; Sari C. Saunders; Thomas R. Crow; Robert J. Naiman; Kimberley D. Brosofske; Glenn D. Mroz; Brain L. Brookshire; Jerry F. Franklin

1999-01-01

Microclimate is the suite of climatic conditions measured in localized areas near the earth's surface (Geiger 1965). These environmental variables, which include temperature, light, windspeed, and moisture, have been critical throughout human history, providing meaningful indicators for habitat selection and other activities. For example, for 2600 years the...

Development of genetic programming-based model for predicting oyster norovirus outbreak risks.

PubMed

Chenar, Shima Shamkhali; Deng, Zhiqiang

2018-01-01

Oyster norovirus outbreaks pose increasing risks to human health and seafood industry worldwide but exact causes of the outbreaks are rarely identified, making it highly unlikely to reduce the risks. This paper presents a genetic programming (GP) based approach to identifying the primary cause of oyster norovirus outbreaks and predicting oyster norovirus outbreaks in order to reduce the risks. In terms of the primary cause, it was found that oyster norovirus outbreaks were controlled by cumulative effects of antecedent environmental conditions characterized by low solar radiation, low water temperature, low gage height (the height of water above a gage datum), low salinity, heavy rainfall, and strong offshore wind. The six environmental variables were determined by using Random Forest (RF) and Binary Logistic Regression (BLR) methods within the framework of the GP approach. In terms of predicting norovirus outbreaks, a risk-based GP model was developed using the six environmental variables and various combinations of the variables with different time lags. The results of local and global sensitivity analyses showed that gage height, temperature, and solar radiation were by far the three most important environmental predictors for oyster norovirus outbreaks, though other variables were also important. Specifically, very low temperature and gage height significantly increased the risk of norovirus outbreaks while high solar radiation markedly reduced the risk, suggesting that low temperature and gage height were associated with the norovirus source while solar radiation was the primary sink of norovirus. The GP model was utilized to hindcast daily risks of oyster norovirus outbreaks along the Northern Gulf of Mexico coast. The daily hindcasting results indicated that the GP model was capable of hindcasting all historical oyster norovirus outbreaks from January 2002 to June 2014 in the Gulf of Mexico with only two false positive outbreaks for the 12.5-year period. The performance of the GP model was characterized with the area under the Receiver Operating Characteristic curve of 0.86, the true positive rate (sensitivity) of 78.53% and the true negative rate (specificity) of 88.82%, respectively, demonstrating the efficacy of the GP model. The findings and results offered new insights into the oyster norovirus outbreaks in terms of source, sink, cause, and predictors. The GP model provided an efficient and effective tool for predicting potential oyster norovirus outbreaks and implementing management interventions to prevent or at least reduce norovirus risks to both the human health and the seafood industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Daily rhythms of physiological parameters in the dromedary camel under natural and laboratory conditions.

PubMed

Al-Haidary, Ahmed A; Abdoun, Khalid A; Samara, Emad M; Okab, Aly B; Sani, Mamane; Refinetti, Roberto

2016-08-01

Camels are well adapted to hot arid environments and can contribute significantly to the economy of developing countries in arid regions of the world. Full understanding of the physiology of camels requires understanding of the internal temporal order of the body, as reflected in daily or circadian rhythms. In the current study, we investigated the daily rhythmicity of 20 physiological variables in camels exposed to natural oscillations of ambient temperature in a desert environment and compared the daily temporal courses of the variables. We also studied the rhythm of core body temperature under experimental conditions with constant ambient temperature in the presence and absence of a light-dark cycle. The obtained results indicated that different physiological variables exhibit different degrees of daily rhythmicity and reach their daily peaks at different times of the day, starting with plasma cholesterol, which peaks 24min after midnight, and ending with plasma calcium, which peaks 3h before midnight. Furthermore, the rhythm of core body temperature persisted in the absence of environmental rhythmicity, thus confirming its endogenous nature. The observed delay in the acrophase of core body temperature rhythm under constant conditions suggests that the circadian period is longer than 24h. Further studies with more refined experimental manipulation of different variables are needed to fully elucidate the causal network of circadian rhythms in dromedary camels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Predicting the potential distribution of the amphibian pathogen Batrachochytrium dendrobatidis in East and Southeast Asia.

PubMed

Moriguchi, Sachiko; Tominaga, Atsushi; Irwin, Kelly J; Freake, Michael J; Suzuki, Kazutaka; Goka, Koichi

2015-04-08

Batrachochytrium dendrobatidis (Bd) is the pathogen responsible for chytridiomycosis, a disease that is associated with a worldwide amphibian population decline. In this study, we predicted the potential distribution of Bd in East and Southeast Asia based on limited occurrence data. Our goal was to design an effective survey area where efforts to detect the pathogen can be focused. We generated ecological niche models using the maximum-entropy approach, with alleviation of multicollinearity and spatial autocorrelation. We applied eigenvector-based spatial filters as independent variables, in addition to environmental variables, to resolve spatial autocorrelation, and compared the model's accuracy and the degree of spatial autocorrelation with those of a model estimated using only environmental variables. We were able to identify areas of high suitability for Bd with accuracy. Among the environmental variables, factors related to temperature and precipitation were more effective in predicting the potential distribution of Bd than factors related to land use and cover type. Our study successfully predicted the potential distribution of Bd in East and Southeast Asia. This information should now be used to prioritize survey areas and generate a surveillance program to detect the pathogen.

Identifying community thresholds for lotic benthic diatoms in response to human disturbance.

PubMed

Tang, Tao; Tang, Ting; Tan, Lu; Gu, Yuan; Jiang, Wanxiang; Cai, Qinghua

2017-06-23

Although human disturbance indirectly influences lotic assemblages through modifying physical and chemical conditions, identifying thresholds of human disturbance would provide direct evidence for preventing anthropogenic degradation of biological conditions. In the present study, we used data obtained from tributaries of the Three Gorges Reservoir in China to detect effects of human disturbance on streams and to identify disturbance thresholds for benthic diatoms. Diatom species composition was significantly affected by three in-stream stressors including TP, TN and pH. Diatoms were also influenced by watershed % farmland and natural environmental variables. Considering three in-stream stressors, TP was positively influenced by % farmland and % impervious surface area (ISA). In contrast, TN and pH were principally affected by natural environmental variables. Among measured natural environmental variables, average annual air temperature, average annual precipitation, and topsoil % CaCO 3 , % gravel, and total exchangeable bases had significant effects on study streams. When effects of natural variables were accounted for, substantial compositional changes in diatoms occurred when farmland or ISA land use exceeded 25% or 0.3%, respectively. Our study demonstrated the rationale for identifying thresholds of human disturbance for lotic assemblages and addressed the importance of accounting for effects of natural factors for accurate disturbance thresholds.

Effect of flow rate on environmental variables and phytoplankton dynamics: results from field enclosures

NASA Astrophysics Data System (ADS)

Zhang, Haiping; Chen, Ruihong; Li, Feipeng; Chen, Ling

2015-03-01

To investigate the effects of flow rate on phytoplankton dynamics and related environment variables, a set of enclosure experiments with different flow rates were conducted in an artificial lake. We monitored nutrients, temperature, dissolved oxygen, pH, conductivity, turbidity, chlorophyll- a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s, which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light, resulting in a dramatic shift in phytoplankton composition, from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However, flow rate significantly enhanced the inter-relationships among environmental variables, in particular by inducing higher water turbidity and vegetative reproduction of periphyton ( Spirogyra). These changes were accompanied by a decrease in underwater light intensity, which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist, because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.

UV reflectance is associated with environmental conditions in Palaearctic Pieris napi (Lepidoptera: Pieridae).

PubMed

Stella, David; Pecháček, Pavel; Meyer-Rochow, Victor Benno; Kleisner, Karel

2018-06-01

The subject of our investigation was the visual features of wing color with special focus on the UV reflectance in the green-veined white butterfly (Pieris napi). Previous studies had concluded that UV reflectance on dorsal wing surfaces is found only in the female P. napi. Based on UV sensitive photography, we analyzed a correlation between 12 geographic and environmental factors and UV reflectance patterns on 3 patches on the forewings of 407 P. napi specimens from the Palaearctic region. Results had shown that females significantly differ from males: they exhibit a 25% higher UV reflectance. To investigate whether and how UV reflectance levels on the forewings and hindwings of both sexes are influenced by the environment, we performed a principal component analysis (PCA) with several environmental variables. For several variables (in particular, latitude and longitude, mean annual temperature and precipitation, and temperature annual range and altitude), the generalized linear model (GLM) model revealed a significant correlation in both sexes. This suggests a link between UV reflectance levels and the environment and distribution of P. napi. We found that stronger UV reflectance is associated with generally more hostile environments and concluded that large-scale environmental factors influence the UV reflectance on the forewings of both male and female green-veined white butterflies. © 2016 Institute of Zoology, Chinese Academy of Sciences.

Connecting differential responses of native and invasive riparian plants to climate change and environmental alteration.

PubMed

Flanagan, Neal E; Richardson, Curtis J; Ho, Mengchi

2015-04-01

Climate change is predicted to impact river systems in the southeastern United States through alterations of temperature, patterns of precipitation and hydrology. Future climate scenarios for the southeastern United States predict (1) surface water temperatures will warm in concert with air temperature, (2) storm flows will increase and base flows will decrease, and (3) the annual pattern of synchronization between hydroperiod and water temperature will be altered. These alterations are expected to disturb floodplain plant communities, making them more vulnerable to establishment of invasive species. The primary objective of this study is to evaluate whether native and invasive riparian plant assemblages respond differently to alterations of climate and land use. To study the response of riparian wetlands to watershed and climate alterations, we utilized an existing natural experiment imbedded in gradients of temperature and hydrology-found among dammed and undammed rivers. We evaluated a suite of environmental variables related to water temperature, hydrology, watershed disturbance, and edaphic conditions to identify the strongest predictors of native and invasive species abundances. We found that native species abundance is strongly influenced by climate-driven variables such as temperature and hydrology, while invasive species abundance is more strongly influenced by site-specific factors such as land use and soil nutrient availability. The patterns of synchronization between plant phenology, annual hydrographs, and annual water temperature cycles may be key factors sustaining the viability of native riparian plant communities. Our results demonstrate the need to understand the interactions between climate, land use, and nutrient management in maintaining the species diversity of riparian plant communities. Future climate change is likely to result in diminished competitiveness of native plant species, while the competitiveness of invasive species will increase due to anthropogenic watershed disturbance and accelerated nutrient and sediment export.

The Immediacy of Arctic Change

NASA Astrophysics Data System (ADS)

Overland, J. E.; Wang, M.; Soreide, N. N.

2015-12-01

Ongoing temperature changes in the Arctic are large relative to lower latitudes; a process known as Arctic Amplification. Arctic temperatures have increased at least 3 times the rate of mid-latitude temperatures relative to the late 20th century, due to multiple interacting feedbacks driven by modest global change. Even if global temperature increases are contained to +2° C by 2040, Arctic (North of 60° N) monthly mean temperatures in fall will increase by +5° C. The Arctic is very likely to be sea ice free during summer before 2040, with the sea ice free duration limited to <5 months. Snow cover will be absent in May and June on most land masses. Whether these changes impact mid-latitude weather events is complex and controversial, as the time period for observing such linkages is short [<10 years] and involves understanding direct forcing by Arctic changes on a chaotic climatic system. Although chaotic internal variability dominates the dynamics of atmospheric circulation, Arctic thermodynamic influences can reinforce regional weather patterns. Extreme Arctic temperature events, as a combination of mean temperature increases combined with natural variability, will become common, nearing and exceeding previous thresholds. Such an event as an analog for the future was the +4° C anomalies for Alaska in November-December 2014 related to recent warm Pacific sea surface temperatures. Thus for the next few decades out to 2040, continuing rapid environmental changes in the Arctic are very likely, despite any mitigation activities, and the appropriate response is to plan for adaptation to meet these mean and extreme event changes. Mitigation is essential to forestall further disasters in the second half of the century. It is important to note such future rapid Arctic amplification, and the potential for environmental surprises, to support those making planning decisions and encourage action.

[Factors associated with incidence of dengue in Costa Rica].

PubMed

Mena, Nelson; Troyo, Adriana; Bonilla-Carrión, Roger; Calderón-Arguedas, Olger

2011-04-01

Determine the extent to which socioeconomic, demographic, geographic, and climate variables affected the incidence of dengue and dengue hemorrhagic fever (D/DH) in Costa Rica during the period 1999-2007. A correlational epidemiologic study was conducted that analyzed the cumulative incidence of D/DH from 1999 to 2007 and its association with different variables in the country's 81 cantons. Information was obtained from secondary sources, and the independent variables used for the analysis were selected on the basis of their representativeness in terms of sociodemographic, environmental, and health coverage factors that affect the epidemiology of D/DH. These variables were divided into four groups of indicators: demographic, socioeconomic, housing, and climate and geographical. The data were analyzed by means of simple and multiple Poisson regressions. The Costa Rican cantons with a higher incidence of D/DH were located primarily near the coast, coinciding with some of the variables studied. Temperature, altitude, and the human poverty index were the most relevant variables in explaining the incidence of D/DH, while temperature was the most significant variable in the multiple analyses. The analyses made it possible to correlate a higher incidence of D/DH with lower-altitude cantons, higher temperature, and a high human poverty index ranking. This information is relevant as a first step toward prioritizing and optimizing actions for the prevention and control of this disease.

Environmental and physical controls on northern terrestrial methane emissions across permafrost zones

USGS Publications Warehouse

Olefeldt, David; Turetsky, Merritt R.; Crill, Patrick M.; McGuire, A. David

2013-01-01

Methane (CH4) emissions from the northern high-latitude region represent potentially significant biogeochemical feedbacks to the climate system. We compiled a database of growing-season CH4 emissions from terrestrial ecosystems located across permafrost zones, including 303 sites described in 65 studies. Data on environmental and physical variables, including permafrost conditions, were used to assess controls on CH4 emissions. Water table position, soil temperature, and vegetation composition strongly influenced emissions and had interacting effects. Sites with a dense sedge cover had higher emissions than other sites at comparable water table positions, and this was an effect that was more pronounced at low soil temperatures. Sensitivity analysis suggested that CH4 emissions from ecosystems where the water table on average is at or above the soil surface (wet tundra, fen underlain by permafrost, and littoral ecosystems) are more sensitive to variability in soil temperature than drier ecosystems (palsa dry tundra, bog, and fen), whereas the latter ecosystems conversely are relatively more sensitive to changes of the water table position. Sites with near-surface permafrost had lower CH4 fluxes than sites without permafrost at comparable water table positions, a difference that was explained by lower soil temperatures. Neither the active layer depth nor the organic soil layer depth was related to CH4 emissions. Permafrost thaw in lowland regions is often associated with increased soil moisture, higher soil temperatures, and increased sedge cover. In our database, lowland thermokarst sites generally had higher emissions than adjacent sites with intact permafrost, but emissions from thermokarst sites were not statistically higher than emissions from permafrost-free sites with comparable environmental conditions. Overall, these results suggest that future changes to terrestrial high-latitude CH4 emissions will be more proximately related to changes in moisture, soil temperature, and vegetation composition than to increased availability of organic matter following permafrost thaw.

The ichthyoplankton assemblage and the environmental variables off the NW and N Iberian Peninsula coasts, in early spring

NASA Astrophysics Data System (ADS)

Rodriguez, J. M.; Gonzalez-Nuevo, G.; Gonzalez-Pola, C.; Cabal, J.

2009-05-01

Ichthyoplankton and mesozooplankton were sampled and fluorescence and physical environmental variables were measured off the NW and N Iberian Peninsula coasts, during April 2005. A total of 51 species of fish larvae, belonging to 26 families, were recorded. Sardina pilchardus, with 43.8% and 58.7% of the total fish egg and larval catches, respectively, dominated the ichthyoplankton assemblage. The study area was divided by a cross-shelf frontal structure into two hydrographic regions that coincided with the Atlantic and Cantabrian geographic regions. Ichthyoplankton abundance was higher in the Cantabrian region while larval diversity was higher in the Atlantic region. This was the main alongshore variability in the structure of the larval fish assemblage. Nevertheless, the stronger variability, related with the presence of a shelf-slope front, was found in the central-eastern Cantabrian region where two major larval fish assemblages, an "outer" and a "coastal", were distinguished. The Atlantic region, where the shelf-slope front was not found, was inhabited by a single larval fish assemblage. Canonical correspondence analysis revealed that, off the NW and N Iberian Peninsula coasts, the horizontal distribution of larval fish species in early spring may be explained by a limited number of environmental variables. Of these, the most important were the physical variables depth and sea surface temperature.

Century-scale Changes in Environmental Synchrony and Variability and their Effects on Populations of Birds and Reproduction of Trees

NASA Astrophysics Data System (ADS)

Koenig, W.

2016-12-01

The ecological impacts of modern global climate change are detectable in a wide variety of phenomena ranging from shifts in species ranges to changes in community composition and human disease dynamics. Thus far, however, little attention has been given to temporal changes in environmental spatial synchrony-the coincident change in abundance or value across the landscape-or environmental variability, despite the importance of these factors as drivers of population rescue and extinction and reproductive dynamics of both animal and plant populations. We quantified spatial synchrony of widespread North American wintering birds species using Audubon Christmas Bird Counts over the past 50 years and seed set variability (mast fruiting) among trees over the past century and found that both spatial synchrony of the birds and seed set variability have significantly increased over these time periods. The first of these results was mirrored by significant increases in spatial synchrony of mean maximum air temperature across North America, primarily during the summer, while the second is consistent with the hypothesis that climate change is resulting in greater seed set variability. These findings suggest the potential for temporal changes in envioronmental synchrony and variability to be affecting a wide range of ecological phenomena by influencing the probability of population rescue and extinction and by affecting ecosystem processes that rely on the resource pulses provided by mast fruiting plants.

Circadian rhythm of body temperature in an ectotherm (Iguana iguana).

PubMed

Tosini, G; Menaker, M

1995-09-01

Ectothermic animals regulate their body temperatures primarily by behavioral adjustment in relation to the thermal characteristics of the environment. Several studies have shown that some vertebrate ectotherms may show a daily pattern of body temperature selection when given a choice of environmental temperature. The pattern of body temperature selection free-runs when the animals are kept in constant darkness, demonstrating the existence of circadian regulation. To test whether there might also be a low amplitude circadian rhythm of body temperature itself, we examined the pattern of body temperature and locomotor activity of the lizard Iguana iguana held in a constant environmental temperature. Both variables were recorded for 3 days in a light:dark cycle and then for 10 days in constant dim light (0.1 lux). Under these conditions the body temperature of the lizard oscillates with a circadian period as does the locomotor behavior. These results demonstrate for the first time that ectothermic animals may display physiologically generated circadian rhythms of body temperature similar to those recorded in endotherms. In some animals the circadian rhythms of body temperature and locomotor activity showed different free-running periods, demonstrating that the body temperature rhythm was not caused by locomotor activity and suggesting internal desyncronization of the two rhythms.

Polynomial response of 2,4-D mineralization to temperature in soils at varying soil moisture contents, slope positions and depths.

PubMed

Shymko, Janna L; Farenhorst, Annemieke; Zvomuya, Francis

2011-01-01

The herbicide 2,4-D [2,4-(dichlorophenoxy) acetic acid] is a widely used broadleaf control agent in cereal production systems. Although 2,4-D soil-residual activity (half-lives) are typically less than 10 days, this herbicide also has as a short-term leaching potential due to its relatively weak retention by soil constituents. Herbicide residual effects and leaching are influenced by environmental variables such as soil moisture and temperature. The objective of this study was to determine impacts of these environmental variables on the magnitude and extent of 2,4-D mineralization in a cultivated undulating Manitoba prairie landscape. Microcosm incubation experiments were utilized to assess 2,4-D half-lives and total mineralization using a 4 × 4 × 3 × 2 factorial design (with soil temperature at 4 levels: 5, 10, 20 and 40°C; soil moisture at 4 levels: 60, 85, 110, 135 % of field capacity; slope position at 3 levels: upper-, mid- and lower-slopes; and soil depth at 2 levels: 0-5 cm and 5-15 cm). Half-lives (t(½)) varied from 3 days to 51 days with the total 2,4-D mineralization (M(T)) ranging from 5.8 to 50.9 %. The four-way interaction (temperature × moisture × slope × depth) significantly (p < 0.001) influenced both t(½) and M(T). Second-order polynomial equations best described the relations of temperature with t(½) and M(T) as was expected from a biological system. However, the interaction and variability of t(½) and M(T) among different temperatures, soil moistures, slope positions, and soil depth combinations indicates that the complex nature of these interacting factors should be considered when applying 2,4-D in agricultural fields and in utilizing these parameters in pesticide fate models.

Temporal Variability of Canopy Light Use Efficiency and its Environmental Controls in a Subtropical Mangrove Wetland

NASA Astrophysics Data System (ADS)

Zhu, X.

2016-12-01

Mangrove wetlands play an important role in global carbon cycle due to their strong carbon sequestration resulting from high plant carbon assimilation and low soil respiration. However, temporal variability of carbon sequestration in mangrove wetlands is less understood since carbon processes of mangrove wetlands are influenced by many complicated and concurrent environmental controls including tidal activities, site climate and soil conditions. Canopy light use efficiency (LUE), is the most important plant physiological parameter that can be used to describe the temporal dynamics of canopy photosynthesis, and therefore a better characterization of temporal variability of canopy LUE will improve our understanding in mangrove photosynthesis and carbon balance. One of our aims is to study the temporal variability of canopy LUE and its environmental controls in a subtropical mangrove wetland. Half-hourly canopy LUE is derived from eddy covariance (EC) carbon flux and photosynthesis active radiation observations, and half-hourly environmental controls we measure include temperature, humidity, precipitation, radiation, tidal height, salinity, etc. Another aim is to explore the links between canopy LUE and spectral indices derived from near-surface tower-based remote sensing (normalized difference vegetation index, enhanced vegetation index, photochemical reflectance index, solar-induced chlorophyll fluorescence, etc.), and then identify potential quantitative relationships for developing remote sensing-based estimation methods of canopy LUE. At present, some instruments in our in-situ observation system have not yet been installed (planned in next months) and therefore we don't have enough measurements to support our analysis. However, a preliminary analysis of our historical EC and climate observations in past several years indicates that canopy LUE shows strong temporal variability and is greatly affected by environmental factors such as tidal activity. Detailed and systematic analyses of temporal variability of canopy LUE and its environmental controls and potential remote sensing estimation methods will be conducted when our in-situ observation system is ready in near future.

Boundaries in ground beetle (Coleoptera: Carabidae) and environmental variables at the edges of forest patches with residential developments

PubMed Central

Davis, Doreen E.

2018-01-01

Background Few studies of edge effects on wildlife objectively identify habitat edges or explore non-linear responses. In this paper, we build on ground beetle (Coleoptera: Carabidae) research that has begun to address these domains by using triangulation wombling to identify boundaries in beetle community structure and composition at the edges of forest patches with residential developments. We hypothesized that edges are characterized by boundaries in environmental variables that correspond to marked discontinuities in vegetation structure between maintained yards and forest. We expected environmental boundaries to be associated with beetle boundaries. Methods We collected beetles and measured environmental variables in 200 m by 200 m sampling grids centered at the edges of three forest patches, each with a rural, suburban, or urban context, in Charlotte, North Carolina, USA. We identified boundaries within each grid at two spatial scales and tested their significance and overlap using boundary statistics and overlap statistics, respectively. We complemented boundary delineation with k-means clustering. Results Boundaries in environmental variables, such as temperature, grass cover, and leaf litter depth, occurred at or near the edges of all three sites, in many cases at both scales. The beetle variables that exhibited the most pronounced boundary structure in relation to edges were total species evenness, generalist abundance, generalist richness, generalist evenness, and Agonum punctiforme abundance. Environmental and beetle boundaries also occurred within forest patches and residential developments, indicating substantial localized spatial variation on either side of edges. Boundaries in beetle and environmental variables that displayed boundary structure at edges significantly overlapped, as did boundaries on either side of edges. The comparison of boundaries and clusters revealed that boundaries formed parts of the borders of patches of similar beetle or environmental condition. Discussion We show that edge effects on ground beetle community structure and composition and environmental variation at the intersection of forest patches and residential developments can be described by boundaries and that these boundaries overlap in space. However, our results also highlight the complexity of edge effects in our system: environmental boundaries were located at or near edges whereas beetle boundaries related to edges could be spatially disjunct from them; boundaries incompletely delineated edges such that only parts of edges were well-described by sharp transitions in beetle and/or environmental variables; and the occurrence of boundaries related to edges was apparently influenced by individual property management practices, site-specific characteristics such as development geometry, and spatial scale. PMID:29333346

Boundaries in ground beetle (Coleoptera: Carabidae) and environmental variables at the edges of forest patches with residential developments.

PubMed

Davis, Doreen E; Gagné, Sara A

2018-01-01

Few studies of edge effects on wildlife objectively identify habitat edges or explore non-linear responses. In this paper, we build on ground beetle (Coleoptera: Carabidae) research that has begun to address these domains by using triangulation wombling to identify boundaries in beetle community structure and composition at the edges of forest patches with residential developments. We hypothesized that edges are characterized by boundaries in environmental variables that correspond to marked discontinuities in vegetation structure between maintained yards and forest. We expected environmental boundaries to be associated with beetle boundaries. We collected beetles and measured environmental variables in 200 m by 200 m sampling grids centered at the edges of three forest patches, each with a rural, suburban, or urban context, in Charlotte, North Carolina, USA. We identified boundaries within each grid at two spatial scales and tested their significance and overlap using boundary statistics and overlap statistics, respectively. We complemented boundary delineation with k -means clustering. Boundaries in environmental variables, such as temperature, grass cover, and leaf litter depth, occurred at or near the edges of all three sites, in many cases at both scales. The beetle variables that exhibited the most pronounced boundary structure in relation to edges were total species evenness, generalist abundance, generalist richness, generalist evenness, and Agonum punctiforme abundance. Environmental and beetle boundaries also occurred within forest patches and residential developments, indicating substantial localized spatial variation on either side of edges. Boundaries in beetle and environmental variables that displayed boundary structure at edges significantly overlapped, as did boundaries on either side of edges. The comparison of boundaries and clusters revealed that boundaries formed parts of the borders of patches of similar beetle or environmental condition. We show that edge effects on ground beetle community structure and composition and environmental variation at the intersection of forest patches and residential developments can be described by boundaries and that these boundaries overlap in space. However, our results also highlight the complexity of edge effects in our system: environmental boundaries were located at or near edges whereas beetle boundaries related to edges could be spatially disjunct from them; boundaries incompletely delineated edges such that only parts of edges were well-described by sharp transitions in beetle and/or environmental variables; and the occurrence of boundaries related to edges was apparently influenced by individual property management practices, site-specific characteristics such as development geometry, and spatial scale.

Northern Russian chironomid-based modern summer temperature data set and inference models

NASA Astrophysics Data System (ADS)

Nazarova, Larisa; Self, Angela E.; Brooks, Stephen J.; van Hardenbroek, Maarten; Herzschuh, Ulrike; Diekmann, Bernhard

2015-11-01

West and East Siberian data sets and 55 new sites were merged based on the high taxonomic similarity, and the strong relationship between mean July air temperature and the distribution of chironomid taxa in both data sets compared with other environmental parameters. Multivariate statistical analysis of chironomid and environmental data from the combined data set consisting of 268 lakes, located in northern Russia, suggests that mean July air temperature explains the greatest amount of variance in chironomid distribution compared with other measured variables (latitude, longitude, altitude, water depth, lake surface area, pH, conductivity, mean January air temperature, mean July air temperature, and continentality). We established two robust inference models to reconstruct mean summer air temperatures from subfossil chironomids based on ecological and geographical approaches. The North Russian 2-component WA-PLS model (RMSEPJack = 1.35 °C, rJack2 = 0.87) can be recommended for application in palaeoclimatic studies in northern Russia. Based on distinctive chironomid fauna and climatic regimes of Kamchatka the Far East 2-component WAPLS model (RMSEPJack = 1.3 °C, rJack2 = 0.81) has potentially better applicability in Kamchatka.

FDR Soil Moisture Sensor for Environmental Testing and Evaluation

NASA Astrophysics Data System (ADS)

Linmao, Ye; longqin, Xue; guangzhou, Zhang; haibo, Chen; likuai, Shi; zhigang, Wu; gouhe, Yu; yanbin, Wang; sujun, Niu; Jin, Ye; Qi, Jin

To test the affect of environmental stresses on a adaptability of soil moisture capacitance sensor(FDR) a number of stresses were induced including vibrational shock as well as temperature and humidity through the use of a CH-I constant humidity chamber with variable temperature. A Vibrational platform was used to exam the resistance and structural integrity of the sensor after vibrations simulating the process of using, transporting and handling the sensor. A Impactive trial platform was used to test the resistance and structural integrity of the sensor after enduring repeated mechanical shocks. An CH-I constant humidity chamber with high-low temperature was used to test the adaptability of sensor in different environments with high temperature, low temperature and constant humidity. Otherwise, scope of magnetic force line of sensor was also tested in this paper. Test show:the capacitance type soil moisture sensor spread a feeling machine to bear heat, high wet and low temperature, at bear impact and vibration experiment in pass an examination, is a kind of environment to adapt to ability very strong instrument;Spread a feeling machine moreover electric field strength function radius scope 7 cms.

Seasonal changes in antioxidant enzyme activities of freshwater biofilms in a metal polluted Mediterranean stream.

PubMed

Bonet, Berta; Corcoll, Natàlia; Acuňa, Vicenç; Sigg, Laura; Behra, Renata; Guasch, Helena

2013-02-01

While seasonal variations in fluvial communities have been extensively investigated, effects of seasonality on community responses to environmental and/or chemical stress are poorly documented. The aim of this study was to describe antioxidant enzyme activity (AEA) variability in fluvial biofilms over an annual cycle, under multi-stress scenarios due to environmental variability (e.g., light intensity, water flow, and temperature) and metal pollution (Zn, Mn and Fe). The annual monitoring study was performed at three sites according to their water and biofilm metal concentrations. Metal concentration was affected by water flow due to dilution. Low flow led to higher dissolved Zn concentrations, and thus to higher Zn accumulation in the biofilm. Water temperature, light intensity and phosphate concentration were the environmental factors which determined the seasonality of biofilm responses, whereas dissolved Zn and Zn accumulation in biofilms were the parameters linked to sites and periods of highest metal pollution. Community algal succession, from diatoms in cold conditions to green algae in warm conditions, was clearer in the non metal-polluted site than in those metal-polluted, presumably due to the selection pressure exerted by metals. Most AEA were related with seasonal environmental variability at the sites with low or no-metal pollution, except glutathione-S-transferase (GST) which was related with Zn (dissolved and accumulated in biofilm) pollution occurring at the most polluted site. We can conclude that seasonal variations of community composition and function are masked by metal pollution. From this study we suggest the use of a multi-biomarker approach, including AEA and a set of biological and physicochemical parameters as an effect-based field tool to assess metal pollution. Copyright © 2012 Elsevier B.V. All rights reserved.

Legume-rhizobia signal exchange: promiscuity and environmental effects.

PubMed

Lira, Mario A; Nascimento, Luciana R S; Fracetto, Giselle G M

2015-01-01

Although signal exchange between legumes and their rhizobia is among the best-known examples of this biological process, most of the more characterized data comes from just a few legume species and environmental stresses. Although a relative wealth of information is available for some model legumes and some of the major pulses such as soybean, little is known about tropical legumes. This relative disparity in current knowledge is also apparent in the research on the effects of environmental stress on signal exchange; cool-climate stresses, such as low-soil temperature, comprise a relatively large body of research, whereas high-temperature stresses and drought are not nearly as well understood. Both tropical legumes and their environmental stress-induced effects are increasingly important due to global population growth (the demand for protein), climate change (increasing temperatures and more extreme climate behavior), and urbanization (and thus heavy metals). This knowledge gap for both legumes and their environmental stresses is compounded because whereas most temperate legume-rhizobia symbioses are relatively specific and cultivated under relatively stable environments, the converse is true for tropical legumes, which tend to be promiscuous, and grow in highly variable conditions. This review will clarify some of this missing information and highlight fields in which further research would benefit our current knowledge.

The evolution of environmental tolerance and range size: a comparison of geographically restricted and widespread Mimulus.

PubMed

Sheth, Seema N; Angert, Amy L

2014-10-01

The geographic ranges of closely related species can vary dramatically, yet we do not fully grasp the mechanisms underlying such variation. The niche breadth hypothesis posits that species that have evolved broad environmental tolerances can achieve larger geographic ranges than species with narrow environmental tolerances. In turn, plasticity and genetic variation in ecologically important traits and adaptation to environmentally variable areas can facilitate the evolution of broad environmental tolerance. We used five pairs of western North American monkeyflowers to experimentally test these ideas by quantifying performance across eight temperature regimes. In four species pairs, species with broader thermal tolerances had larger geographic ranges, supporting the niche breadth hypothesis. As predicted, species with broader thermal tolerances also had more within-population genetic variation in thermal reaction norms and experienced greater thermal variation across their geographic ranges than species with narrow thermal tolerances. Species with narrow thermal tolerance may be particularly vulnerable to changing climatic conditions due to lack of plasticity and insufficient genetic variation to respond to novel selection pressures. Conversely, species experiencing high variation in temperature across their ranges may be buffered against extinction due to climatic changes because they have evolved tolerance to a broad range of temperatures. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Validation of a biotelemetric technique, using ambulatory miniature black globe thermometers, to quantify thermoregulatory behaviour in ungulates.

PubMed

Hetem, Robyn S; Maloney, Shane K; Fuller, Andrea; Meyer, Leith C R; Mitchell, Duncan

2007-06-01

Behavioural thermoregulation is an animal's primary defence against changes in the thermal environment. We aimed to validate a remote technique to quantify the thermal environment behaviourally selected by free-ranging ungulates. First, we demonstrated that the temperature of miniature, 30 mm diameter, black globes (miniglobes) could be converted to standard, 150 mm diameter, black globe temperatures. Miniglobe temperature sensors subsequently were fitted to collars on three free-ranging ungulates, namely blue wildebeest (Connochaetes taurinus), impala (Aepyceros melampus) and horse (Equus caballus). Behavioural observations were reflected in animal miniglobe temperatures which differed from those recorded by an identical miniglobe on a nearby exposed weather station. The wildebeest often selected sites protected from the wind, whereas the impala and the horse sheltered from the sun. Nested analysis of variances revealed that the impala and horse selected significantly less variable environments than those recorded at the weather station (P<0.001) over a 20-min time interval, whereas, the microclimates selected by wildebeest tended to be more variable (P=0.08). Correlation of animal miniglobe against weather station miniglobe temperature resulted in regression slopes significantly less than one (P<0.001) for all species studied, implying that, overall, the animals selected cooler microclimates at high environmental heat loads and/or warmer microclimates at low environmental heat loads. We, therefore, have developed an ambulatory device, which can be attached to free-ranging animals, to remotely quantify thermoregulatory behaviour and selected microclimates. (c) 2007 Wiley-Liss, Inc.

Temporal dynamic of wood formation in Pinus cembra along the alpine treeline ecotone and the effect of climate variables.

PubMed

Gruber, Andreas; Baumgartner, Daniel; Zimmermann, Jolanda; Oberhuber, Walter

2009-06-01

We determined the temporal dynamic of cambial activity and xylem development of stone pine (Pinus cembra L.) throughout the treeline ecotone. Repeated micro-sampling of the developing tree ring was carried out during the growing seasons 2006 and 2007 at the timberline (1950 m a.s.l.), treeline (2110 m a.s.l.) and within the krummholz belt (2180 m a.s.l.) and the influence of climate variables on intra-annual wood formation was determined.At the beginning of both growing seasons, highest numbers of cambial and enlarging cells were observed at the treeline. Soil temperatures at time of initiation of cambial activity were c. 1.5 °C higher at treeline (open canopy) compared to timberline (closed canopy), suggesting that a threshold root-zone temperature is involved in triggering onset of above ground stem growth.The rate of xylem cell production determined in two weekly intervals during June through August 2006-2007 was significantly correlated with air temperature (temperature sums expressed as degree-days and mean daily maximum temperature) at the timberline only. Lack of significant relationships between tracheid production and temperature variables at the treeline and within the krummholz belt support past dendroclimatological studies that more extreme environmental conditions (e.g., wind exposure, frost desiccation, late frost) increasingly control tree growth above timberline.Results of this study revealed that spatial and temporal (i.e. year-to-year) variability in timing and dynamic of wood formation of Pinus cembra is strongly influenced by local site factors within the treeline ecotone and the dynamics of seasonal temperature variation, respectively.

40 CFR 63.137 - Process wastewater provisions-oil-water separators.

Code of Federal Regulations, 2010 CFR

2010-07-01

... separators. 63.137 Section 63.137 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... for other emission variables such as temperature and barometric pressure, or (ii) An engineering...)(1) and the schedule specified in paragraphs (c)(1) and (c)(2) of this section. (1) Measurement of...

TEMPERATURE EFFECTS ON THE SYNTHESIS OF SI-FERRIHYDRITE NANOPARTICLES OF VARIABLE SIZES IDENTIFIED BY MAGNETIC MEASUREMENTS

EPA Science Inventory

Ferrihydrite is an antiferromagnetic iron oxyhydroxide formed as an ubiquitous product of natural iron diagenesis, and found in iron-containing water, soil, river sediment and oceanic crust. As such, it is a sensitive indicator or proxy of environmental change. This iron phase ha...

Advanced Plant Habitat (APH)

NASA Technical Reports Server (NTRS)

Richards, Stephanie E. (Compiler); Levine, Howard G.; Reed, David W.

2016-01-01

The Advanced Plant Habitat (APH) hardware will be a large growth volume plant habitat, capable of hosting multigenerational studies, in which environmental variables (e.g., temperature, relative humidity, carbon dioxide level light intensity and spectral quality) can be tracked and controlled in support of whole plant physiological testing and Bio-regenerative Life Support System investigations.

Lab-scaled model to evaluate odor and gas production from cattle confinement facilities with deep bedded packs

USDA-ARS?s Scientific Manuscript database

A lab-scaled simulated bedded pack model was developed to study air quality and nutrient composition of deep-bedded packs found in cattle monoslope facilities. This protocol has been used to effectively evaluate many different bedding materials, environmental variables (temperature, humidity), and ...

Developmental phenotypic plasticity helps bridge stochastic weather events associated with climate change.

PubMed

Burggren, Warren

2018-05-10

The slow, inexorable rise in annual average global temperatures and acidification of the oceans are often advanced as consequences of global change. However, many environmental changes, especially those involving weather (as opposed to climate), are often stochastic, variable and extreme, particularly in temperate terrestrial or freshwater habitats. Moreover, few studies of animal and plant phenotypic plasticity employ realistic (i.e. short-term, stochastic) environmental change in their protocols. Here, I posit that the frequently abrupt environmental changes (days, weeks, months) accompanying much longer-term general climate change (e.g. global warming over decades or centuries) require consideration of the true nature of environmental change (as opposed to statistical means) coupled with an expansion of focus to consider developmental phenotypic plasticity. Such plasticity can be in multiple forms - obligatory/facultative, beneficial/deleterious - depending upon the degree and rate of environmental variability at specific points in organismal development. Essentially, adult phenotypic plasticity, as important as it is, will be irrelevant if developing offspring lack sufficient plasticity to create modified phenotypes necessary for survival. © 2018. Published by The Company of Biologists Ltd.

Integrated presentation of ecological risk from multiple stressors

NASA Astrophysics Data System (ADS)

Goussen, Benoit; Price, Oliver R.; Rendal, Cecilie; Ashauer, Roman

2016-10-01

Current environmental risk assessments (ERA) do not account explicitly for ecological factors (e.g. species composition, temperature or food availability) and multiple stressors. Assessing mixtures of chemical and ecological stressors is needed as well as accounting for variability in environmental conditions and uncertainty of data and models. Here we propose a novel probabilistic ERA framework to overcome these limitations, which focusses on visualising assessment outcomes by construct-ing and interpreting prevalence plots as a quantitative prediction of risk. Key components include environmental scenarios that integrate exposure and ecology, and ecological modelling of relevant endpoints to assess the effect of a combination of stressors. Our illustrative results demonstrate the importance of regional differences in environmental conditions and the confounding interactions of stressors. Using this framework and prevalence plots provides a risk-based approach that combines risk assessment and risk management in a meaningful way and presents a truly mechanistic alternative to the threshold approach. Even whilst research continues to improve the underlying models and data, regulators and decision makers can already use the framework and prevalence plots. The integration of multiple stressors, environmental conditions and variability makes ERA more relevant and realistic.

Integrated presentation of ecological risk from multiple stressors.

PubMed

Goussen, Benoit; Price, Oliver R; Rendal, Cecilie; Ashauer, Roman

2016-10-26

Current environmental risk assessments (ERA) do not account explicitly for ecological factors (e.g. species composition, temperature or food availability) and multiple stressors. Assessing mixtures of chemical and ecological stressors is needed as well as accounting for variability in environmental conditions and uncertainty of data and models. Here we propose a novel probabilistic ERA framework to overcome these limitations, which focusses on visualising assessment outcomes by construct-ing and interpreting prevalence plots as a quantitative prediction of risk. Key components include environmental scenarios that integrate exposure and ecology, and ecological modelling of relevant endpoints to assess the effect of a combination of stressors. Our illustrative results demonstrate the importance of regional differences in environmental conditions and the confounding interactions of stressors. Using this framework and prevalence plots provides a risk-based approach that combines risk assessment and risk management in a meaningful way and presents a truly mechanistic alternative to the threshold approach. Even whilst research continues to improve the underlying models and data, regulators and decision makers can already use the framework and prevalence plots. The integration of multiple stressors, environmental conditions and variability makes ERA more relevant and realistic.

Day-night contrast as source of health for the human circadian system.

PubMed

Martinez-Nicolas, Antonio; Madrid, Juan Antonio; Rol, Maria Angeles

2014-04-01

Modern societies are characterized by a 24/7 lifestyle (LS) with no environmental differences between day and night, resulting in weak zeitgebers (weak day light, absence of darkness during night, constant environmental temperature, sedentary LS and frequent snacking), and as a consequence, in an impaired circadian system (CS) through a process known as chronodisruption. Both weak zeitgebers and CS impairment are related to human pathologies (certain cancers, metabolic syndrome and affective and cognitive disorders), but little is known about how to chronoenhance the CS. The aim of this work is to propose practical strategies for chronoenhancement, based on accentuating the day/night contrast. For this, 131 young subjects were recruited, and their wrist temperature (WT), activity, body position, light exposure, environmental temperature and sleep were recorded under free-living conditions for 1 week. Subjects with high contrast (HC) and low contrast (LC) for each variable were selected to analyze the HC effect in activity, body position, environmental temperature, light exposure and sleep would have on WT. We found that HC showed better rhythms than LC for every variable except sleep. Subjects with HC and LC for WT also demonstrated differences in LS, where HC subjects had a slightly advanced night phase onset and a general increase in day/night contrast. In addition, theoretical high day/night contrast calculated using mathematical models suggests an improvement by means of LS contrast. Finally, some individuals classified as belonging to the HC group in terms of WT when they are exposed to the LS characteristic of the LC group, while others exhibit WT arrhythmicity despite their good LS habits, revealing two different WT components: an exogenous component modified by LS and another endogenous component that is refractory to it. Therefore, intensifying day/night contrast in subject's LS has proven to be a feasible measure to chronoenhance the CS.

Environmental drivers of cambial phenology in Great Basin bristlecone pine.

PubMed

Ziaco, Emanuele; Biondi, Franco; Rossi, Sergio; Deslauriers, Annie

2016-07-01

The timing of wood formation is crucial to determine how environmental factors affect tree growth. The long-lived bristlecone pine (Pinus longaeva D. K. Bailey) is a foundation treeline species in the Great Basin of North America reaching stem ages of about 5000 years. We investigated stem cambial phenology and radial size variability to quantify the relative influence of environmental variables on bristlecone pine growth. Repeated cellular measurements and half-hourly dendrometer records were obtained during 2013 and 2014 for two high-elevation stands included in the Nevada Climate-ecohydrological Assessment Network. Daily time series of stem radial variations showed rehydration and expansion starting in late April-early May, prior to the onset of wood formation at breast height. Formation of new xylem started in June and lasted until mid-September. There were no differences in phenological timing between the two stands, or in the air and soil temperature thresholds for the onset of xylogenesis. A multiple logistic regression model highlighted a separate effect of air and soil temperature on xylogenesis, the relevance of which was modulated by the interaction with vapor pressure and soil water content. While air temperature plays a key role in cambial resumption after winter dormancy, soil thermal conditions coupled with snowpack dynamics also influence the onset of wood formation by regulating plant-soil water exchanges. Our results help build a physiological understanding of climate-growth relationships in P. longaeva, the importance of which for dendroclimatic reconstructions can hardly be overstated. In addition, environmental drivers of xylogenesis at the treeline ecotone, by controlling the growth of dominant species, ultimately determine ecosystem responses to climatic change. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Baleen whale abundance and distribution in relation to environmental variables and prey density in the Eastern Bering Sea

NASA Astrophysics Data System (ADS)

Zerbini, Alexandre N.; Friday, Nancy A.; Palacios, Daniel M.; Waite, Janice M.; Ressler, Patrick H.; Rone, Brenda K.; Moore, Sue E.; Clapham, Phillip J.

2016-12-01

The Bering Sea is one of the most productive marine ecosystems in the world and an important habitat for various marine mammal species. Once abundant in this region, most baleen whale species were severely depleted by commercial whaling in the 19th and early 20th centuries. Since their protection in mid-20th century, baleen whale populations have been recovering and reoccupying their historical habitats. These species can consume large amounts of their prey and thus can modify the local structure of ecosystems. Characterizing the extent to which environmental conditions and prey density influence baleen whale abundance in the Eastern Bering Sea is essential to improve our understanding of ecosystem dynamics and to predict how these species might respond to ecosystem variability associated with climate changes. In this study, physiographic, oceanographic, and biological datasets from 2008 to 2010 were combined to model the habitat characteristics of fin whales, humpback whales, and minke whales in the EBS in early summer (June and July) using generalized additive models (GAMs). The explained deviances of the best-supported models were 54.9%, 20.6%, and 68.3% for minke, fin and humpback whales, respectively. Minke and fin whales had similar distribution patterns in the EBS but their abundance was predicted by different explanatory variables. Euphausiid and pollock biomasses, and depth were important predictors of minke whale numbers, while distance to shore, euphausiid biomass, distance to the 200 m isobath, and chlorophyll-a concentration better explained fin whale abundance. Humpback whales showed a preference for shallow, coastal waters north of the Alaska Peninsula. For this species, sea surface temperature, depth, chlorophyll-a concentration and euphausid biomass were important predictors of abundance. This study is the first to provide a habitat baseline for baleen whales in the EBS based on a quantitative assessment of the relationship between whale abundance, environmental variables, and density of euphausiids and age-1 pollock in early summer. Because this study was conducted during a cold temperature regime in the Bering Sea, additional research is needed to assess how whales respond to environmental variables and prey biomass in years with warm conditions.

Vegetative and reproductive phenology of a floodplain tree species Barringtonia acutangula from North East India.

PubMed

Nath, Shikhasmita; Nath, Arun Jyoti; Das, Ashesh Kumar

2016-03-01

Vegetative and reproductive phenology of Barringtonia acutangula, a floodplain tree species was studied at Chatla floodplain, Assam North East India with the aim to investigate vegetative and reproductive phenology under stressful environment of seasonal submergence and to assess the impact of environmental variables (temperature and precipitation) on tree phenophases. Quantitative assessment was made at 15 day interval for all the phenophases (leaf initiation, leaf-fall, flowering and fruiting) by tagging 40 (forty) trees over aperiod of two years (2012-14).To test seasonal influence on the phenology of Barringtonia acutangula different phenophases were correlated with environmental variables and statistical spearman's rank correlation coefficient was employed. Aridity index was computed that delineate influence of rainfall and temperature together on any phenophases. Leaf initiation showed positively significant correlation with temperature (r(s) = 0.601, p = < .05) during the year 2012-2013 whereas it was significantly correlated with rainfall (r(s) = 0.583, p = < .05) and aridity index (r(s) = 0.583, p = < .05) during the year 2013-2014. Leaf-fall was significant negatively correlated with temperature (r(s) = -0.623, p = < .05), rainfall (r(s) = -0.730, p = < .01) and aridity index (r(s) = -0.730, p = < .01) for both the studied years. Flowering was significantly influenced by temperature (r(s) = 0.639, p = < .05), rainfall (r(s) = 0.890, p = < .01) and aridity index (r(s) = 0.890, p = < .01) while in one month lag flowering was significantly correlated with rainfall (r(s) = 0.678, p = < .01) in 2012-13. Fruiting was also positively significant with temperature (r(s) = 0.795, P < .05), rainfall (r(s) = 0.835, P < .01) and aridity index (r(s) = 0.835, P < .01) for both the years. During one month lag period fruiting was positively correlated with temperature, rainfall and aridity index in both the years. Temperature, rainfall and aridity index were major determinants of the various vegetative and reproductive phenology of B. acutangula and any changes in these variables in future due to climate change, might have profound effect on phenophases of this tree species.

Integrating environmental variables and geospatial technologies in landscape scale habitat modelling of edible stink bugs in Zimbabwe

NASA Astrophysics Data System (ADS)

Masocha, Mhosisi; Dube, Timothy; Maziva, Tendai

2018-06-01

Encosternum delegorguei spinola (edible stink bugs) is renowned for its high protein and contribution to the local economies of the people in Africa. Although many studies have evaluated the economic and nutritional importance of E. delegorguei, little is known about its geographic distribution and habitat yet the insects are an important source of protein and money for many people in Southern Africa. In this study maximum entropy model was used to predict the probability of presence of E. delegorguei in southern Zimbabwe. The environmental factors governing its geographic distribution in Zimbabwe were also evaluated. Presence/absence data were selected along thirty-five randomly selected transects. The climatic and topographic variables used to predict the distribution of E. delegorguei were: maximum temperature of the warmest month; minimum temperature of the coldest month; the normalised difference vegetation index (NDVI); altitude; slope; and aspect. It was found that E. delegorguei is most likely to occur on steep slopes with high NDVI located at an altitude ranging of 856 and 1450 m above sea level. These suitable habitats are characterised by mild temperatures ranging from 17 °C to 28 °C. These results are in agreement with previous studies indicating that E. delegorguei is sensitive to temperature, as well as tree cover and may contribute towards conserving its habitat, which is being fragmented by anthropogenic disturbance.

Short-term association between environmental factors and hospital admissions due to dementia in Madrid.

PubMed

Linares, C; Culqui, D; Carmona, R; Ortiz, C; Díaz, J

2017-01-01

Spain has one of the highest proportions of dementia in the world among the population aged 60 years or over. Recent studies link various environmental factors to neurocognitive-type diseases. This study sought to analyse whether urban risk factors such as traffic noise, pollutants and heat waves might have a short-term impact on exacerbation of symptoms of dementia, leading to emergency hospital admission. We conducted a longitudinal ecological time-series study, with the dependent variable being the number of daily dementia-related emergency (DDE) hospital admissions to Madrid municipal hospitals (ICD-10 codes 290.0-290.2, 290.4-290.9, 294.1-294) from 01 to 01-2001 to 31-12-2009, as obtained from the Hospital Morbidity Survey (National Statistics Institute). The measures used were as follows: for noise pollution, Leqd, equivalent diurnal noise level (from 8 to 22h), and Leqn, equivalent nocturnal noise level (from 22 to 8h) in dB(A); for chemical pollution, mean daily NO2, PM2.5, PM1 as provided by the Madrid Municipal Air Quality Monitoring Grid; and lastly, maximum daily temperature (°C), as supplied by the State Meteorological Agency. Scatterplot diagrams were plotted to assess the type of functional relationship existing between the main variable of analysis and the environmental variables. The lags of the environmental variables were calculated to analyse the timing of the effect. Poisson regression models were fitted, controlling for trends and seasonalities, to quantify relative risk (RR). During the study period, there were 1175 DDE hospital admissions. These admissions displayed a linear functional relationship without a threshold in the case of Leqd. The RR of DDE admissions was 1.15 (1.11-1.20) for an increase of 1dB in Leqd, with impact at lag 0. In the case of maximum daily temperature, there was a threshold temperature of 34°C, with an increase of 1°C over this threshold posing an RR of 1.19 (1.09-1.30) at lag 1. The only pollutant to show an association with DDE hospital admissions was O3 at lag 5, with an RR of 1.09 (1.04-1.15) for an increase of 10µg/m 3 CONCLUSIONS: Diurnal traffic noise, heat waves and tropospheric ozone may exacerbate the symptoms of dementia to the point of requiring emergency admission to hospital. Lowering exposure levels to these environmental factors could reduce dementia-related admissions in Madrid. Copyright © 2016 Elsevier Inc. All rights reserved.

Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective

PubMed Central

Cruz-Motta, Juan José; Miloslavich, Patricia; Palomo, Gabriela; Iken, Katrin; Konar, Brenda; Pohle, Gerhard; Trott, Tom; Benedetti-Cecchi, Lisandro; Herrera, César; Hernández, Alejandra; Sardi, Adriana; Bueno, Andrea; Castillo, Julio; Klein, Eduardo; Guerra-Castro, Edlin; Gobin, Judith; Gómez, Diana Isabel; Riosmena-Rodríguez, Rafael; Mead, Angela; Bigatti, Gregorio; Knowlton, Ann; Shirayama, Yoshihisa

2010-01-01

Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses. PMID:21179546

Association between environmental factors and hospitalisations for bronchiectasis in Badalona, Barcelona, Spain (2007-2015).

PubMed

Garcia-Olivé, Ignasi; Radua, Joaquim; Sánchez-Berenguer, Dan; Hernández-Biette, Agnes; Raya-Márquez, Patricia; Stojanovic, Zoran; Martínez-Rivera, Carlos; Fernandez Serrano, Silvia; Ruiz Manzano, Juan

2018-04-13

The relationship between environmental factors and the exacerbation of respiratory diseases has been widely studied. However, there are no studies examining the relationship between these factors and bronchiectasis exacerbations. Our objective was to analyse the association between various environmental factors and hospitalisation for bronchiectasis. This was a retrospective observational study conducted at two hospitals in Badalona (Barcelona). The number of hospital admissions for exacerbation of bronchiectasis between 2007 and 2015 was obtained. Through multiple regression we analysed the relationship between the number of exacerbations and mean monthly values of temperature, SO 2 , NO, NO 2 , O 3 and CO. Temperature, SO 2 , NO, NO 2 , O 3 and CO were significantly associated with an increase in admissions due to exacerbation of bronchiectasis. By controlling the effect of temperature on the pollution variables, only SO 2 maintained statistical significance (P=.008). We have detected an increase in hospital admissions for exacerbation of bronchiectasis with increases in the atmospheric concentration of SO 2 and the decrease in temperature. Prospective studies with different geographical locations to confirm these results are needed. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

The Role of Auxiliary Variables in Deterministic and Deterministic-Stochastic Spatial Models of Air Temperature in Poland

NASA Astrophysics Data System (ADS)

Szymanowski, Mariusz; Kryza, Maciej

2017-02-01

Our study examines the role of auxiliary variables in the process of spatial modelling and mapping of climatological elements, with air temperature in Poland used as an example. The multivariable algorithms are the most frequently applied for spatialization of air temperature, and their results in many studies are proved to be better in comparison to those obtained by various one-dimensional techniques. In most of the previous studies, two main strategies were used to perform multidimensional spatial interpolation of air temperature. First, it was accepted that all variables significantly correlated with air temperature should be incorporated into the model. Second, it was assumed that the more spatial variation of air temperature was deterministically explained, the better was the quality of spatial interpolation. The main goal of the paper was to examine both above-mentioned assumptions. The analysis was performed using data from 250 meteorological stations and for 69 air temperature cases aggregated on different levels: from daily means to 10-year annual mean. Two cases were considered for detailed analysis. The set of potential auxiliary variables covered 11 environmental predictors of air temperature. Another purpose of the study was to compare the results of interpolation given by various multivariable methods using the same set of explanatory variables. Two regression models: multiple linear (MLR) and geographically weighted (GWR) method, as well as their extensions to the regression-kriging form, MLRK and GWRK, respectively, were examined. Stepwise regression was used to select variables for the individual models and the cross-validation method was used to validate the results with a special attention paid to statistically significant improvement of the model using the mean absolute error (MAE) criterion. The main results of this study led to rejection of both assumptions considered. Usually, including more than two or three of the most significantly correlated auxiliary variables does not improve the quality of the spatial model. The effects of introduction of certain variables into the model were not climatologically justified and were seen on maps as unexpected and undesired artefacts. The results confirm, in accordance with previous studies, that in the case of air temperature distribution, the spatial process is non-stationary; thus, the local GWR model performs better than the global MLR if they are specified using the same set of auxiliary variables. If only GWR residuals are autocorrelated, the geographically weighted regression-kriging (GWRK) model seems to be optimal for air temperature spatial interpolation.

Subsurface temperature estimation from climatology and satellite SST for the sea around Korean Peninsula 1Bong-Guk, Kim, 1Yang-Ki, Cho, 1Bong-Gwan, Kim, 1Young-Gi, Kim, 1Ji-Hoon, Jung 1School of Earth and Environmental Sciences, Seoul National University

NASA Astrophysics Data System (ADS)

Kim, Bong-Guk; Cho, Yang-Ki; Kim, Bong-Gwan; Kim, Young-Gi; Jung, Ji-Hoon

2015-04-01

Subsurface temperature plays an important role in determining heat contents in the upper ocean which are crucial in long-term and short-term weather systems. Furthermore, subsurface temperature affects significantly ocean ecology. In this study, a simple and practical algorithm has proposed. If we assume that subsurface temperature changes are proportional to surface heating or cooling, subsurface temperature at each depth (Sub_temp) can be estimated as follows PIC whereiis depth index, Clm_temp is temperature from climatology, dif0 is temperature difference between satellite and climatology in the surface, and ratio is ratio of temperature variability in each depth to surface temperature variability. Subsurface temperatures using this algorithm from climatology (WOA2013) and satellite SST (OSTIA) where calculated in the sea around Korean peninsula. Validation result with in-situ observation data show good agreement in the upper 50 m layer with RMSE (root mean square error) less than 2 K. The RMSE is smallest with less than 1 K in winter when surface mixed layer is thick, and largest with about 2~3 K in summer when surface mixed layer is shallow. The strong thermocline and large variability of the mixed layer depth might result in large RMSE in summer. Applying of mixed layer depth information for the algorithm may improve subsurface temperature estimation in summer. Spatial-temporal details on the improvement and its causes will be discussed.

Time series analysis of cholera in Matlab, Bangladesh, during 1988-2001.

PubMed

Ali, Mohammad; Kim, Deok Ryun; Yunus, Mohammad; Emch, Michael

2013-03-01

The study examined the impact of in-situ climatic and marine environmental variability on cholera incidence in an endemic area of Bangladesh and developed a forecasting model for understanding the magnitude of incidence. Diarrhoea surveillance data collected between 1988 and 2001 were obtained from a field research site in Matlab, Bangladesh. Cholera cases were defined as Vibrio cholerae O1 isolated from faecal specimens of patients who sought care at treatment centres serving the Matlab population. Cholera incidence for 168 months was correlated with remotely-sensed sea-surface temperature (SST) and in-situ environmental data, including rainfall and ambient temperature. A seasonal autoregressive integrated moving average (SARIMA) model was used for determining the impact of climatic and environmental variability on cholera incidence and evaluating the ability of the model to forecast the magnitude of cholera. There were 4,157 cholera cases during the study period, with an average of 1.4 cases per 1,000 people. Since monthly cholera cases varied significantly by month, it was necessary to stabilize the variance of cholera incidence by computing the natural logarithm to conduct the analysis. The SARIMA model shows temporal clustering of cholera at one- and 12-month lags. There was a 6% increase in cholera incidence with a minimum temperature increase of one degree celsius in the current month. For increase of SST by one degree celsius, there was a 25% increase in the cholera incidence at currrent month and 18% increase in the cholera incidence at two months. Rainfall did not influenc to cause variation in cholera incidence during the study period. The model forecast the fluctuation of cholera incidence in Matlab reasonably well (Root mean square error, RMSE: 0.108). Thus, the ambient and sea-surface temperature-based model could be used in forecasting cholera outbreaks in Matlab.

Climate Exposure of US National Parks in a New Era of Change

PubMed Central

Monahan, William B.; Fisichelli, Nicholas A.

2014-01-01

US national parks are challenged by climate and other forms of broad-scale environmental change that operate beyond administrative boundaries and in some instances are occurring at especially rapid rates. Here, we evaluate the climate change exposure of 289 natural resource parks administered by the US National Park Service (NPS), and ask which are presently (past 10 to 30 years) experiencing extreme (<5th percentile or >95th percentile) climates relative to their 1901–2012 historical range of variability (HRV). We consider parks in a landscape context (including surrounding 30 km) and evaluate both mean and inter-annual variation in 25 biologically relevant climate variables related to temperature, precipitation, frost and wet day frequencies, vapor pressure, cloud cover, and seasonality. We also consider sensitivity of findings to the moving time window of analysis (10, 20, and 30 year windows). Results show that parks are overwhelmingly at the extreme warm end of historical temperature distributions and this is true for several variables (e.g., annual mean temperature, minimum temperature of the coldest month, mean temperature of the warmest quarter). Precipitation and other moisture patterns are geographically more heterogeneous across parks and show greater variation among variables. Across climate variables, recent inter-annual variation is generally well within the range of variability observed since 1901. Moving window size has a measureable effect on these estimates, but parks with extreme climates also tend to exhibit low sensitivity to the time window of analysis. We highlight particular parks that illustrate different extremes and may facilitate understanding responses of park resources to ongoing climate change. We conclude with discussion of how results relate to anticipated future changes in climate, as well as how they can inform NPS and neighboring land management and planning in a new era of change. PMID:24988483

Climate exposure of US national parks in a new era of change.

PubMed

Monahan, William B; Fisichelli, Nicholas A

2014-01-01

US national parks are challenged by climate and other forms of broad-scale environmental change that operate beyond administrative boundaries and in some instances are occurring at especially rapid rates. Here, we evaluate the climate change exposure of 289 natural resource parks administered by the US National Park Service (NPS), and ask which are presently (past 10 to 30 years) experiencing extreme (<5th percentile or >95th percentile) climates relative to their 1901-2012 historical range of variability (HRV). We consider parks in a landscape context (including surrounding 30 km) and evaluate both mean and inter-annual variation in 25 biologically relevant climate variables related to temperature, precipitation, frost and wet day frequencies, vapor pressure, cloud cover, and seasonality. We also consider sensitivity of findings to the moving time window of analysis (10, 20, and 30 year windows). Results show that parks are overwhelmingly at the extreme warm end of historical temperature distributions and this is true for several variables (e.g., annual mean temperature, minimum temperature of the coldest month, mean temperature of the warmest quarter). Precipitation and other moisture patterns are geographically more heterogeneous across parks and show greater variation among variables. Across climate variables, recent inter-annual variation is generally well within the range of variability observed since 1901. Moving window size has a measureable effect on these estimates, but parks with extreme climates also tend to exhibit low sensitivity to the time window of analysis. We highlight particular parks that illustrate different extremes and may facilitate understanding responses of park resources to ongoing climate change. We conclude with discussion of how results relate to anticipated future changes in climate, as well as how they can inform NPS and neighboring land management and planning in a new era of change.

A new temperature profiling probe for investigating groundwater-surface water interaction

USGS Publications Warehouse

Naranjo, Ramon C.; Robert Turcotte,

2015-01-01

Measuring vertically nested temperatures at the streambed interface poses practical challenges that are addressed here with a new discrete subsurface temperature profiling probe. We describe a new temperature probe and its application for heat as a tracer investigations to demonstrate the probe's utility. Accuracy and response time of temperature measurements made at 6 discrete depths in the probe were analyzed in the laboratory using temperature bath experiments. We find the temperature probe to be an accurate and robust instrument that allows for easily installation and long-term monitoring in highly variable environments. Because the probe is inexpensive and versatile, it is useful for many environmental applications that require temperature data collection for periods of several months in environments that are difficult to access or require minimal disturbance.

Temperature Effects on Biomass and Regeneration of Vegetation in a Geothermal Area

PubMed Central

Nishar, Abdul; Bader, Martin K.-F.; O’Gorman, Eoin J.; Deng, Jieyu; Breen, Barbara; Leuzinger, Sebastian

2017-01-01

Understanding the effects of increasing temperature is central in explaining the effects of climate change on vegetation. Here, we investigate how warming affects vegetation regeneration and root biomass and if there is an interactive effect of warming with other environmental variables. We also examine if geothermal warming effects on vegetation regeneration and root biomass can be used in climate change experiments. Monitoring plots were arranged in a grid across the study area to cover a range of soil temperatures. The plots were cleared of vegetation and root-free ingrowth cores were installed to assess above and below-ground regeneration rates. Temperature sensors were buried in the plots for continued soil temperature monitoring. Soil moisture, pH, and soil chemistry of the plots were also recorded. Data were analyzed using least absolute shrinkage and selection operator and linear regression to identify the environmental variable with the greatest influence on vegetation regeneration and root biomass. There was lower root biomass and slower vegetation regeneration in high temperature plots. Soil temperature was positively correlated with soil moisture and negatively correlated with soil pH. Iron and sulfate were present in the soil in the highest quantities compared to other measured soil chemicals and had a strong positive relationship with soil temperature. Our findings suggest that soil temperature had a major impact on root biomass and vegetation regeneration. In geothermal fields, vegetation establishment and growth can be restricted by low soil moisture, low soil pH, and an imbalance in soil chemistry. The correlation between soil moisture, pH, chemistry, and plant regeneration was chiefly driven by soil temperature. Soil temperature was negatively correlated to the distance from the geothermal features. Apart from characterizing plant regeneration on geothermal soils, this study further demonstrates a novel approach to global warming experiments, which could be particularly useful in low heat flow geothermal systems that more realistically mimic soil warming. PMID:28326088

Temperature Effects on Biomass and Regeneration of Vegetation in a Geothermal Area.

PubMed

Nishar, Abdul; Bader, Martin K-F; O'Gorman, Eoin J; Deng, Jieyu; Breen, Barbara; Leuzinger, Sebastian

2017-01-01

Understanding the effects of increasing temperature is central in explaining the effects of climate change on vegetation. Here, we investigate how warming affects vegetation regeneration and root biomass and if there is an interactive effect of warming with other environmental variables. We also examine if geothermal warming effects on vegetation regeneration and root biomass can be used in climate change experiments. Monitoring plots were arranged in a grid across the study area to cover a range of soil temperatures. The plots were cleared of vegetation and root-free ingrowth cores were installed to assess above and below-ground regeneration rates. Temperature sensors were buried in the plots for continued soil temperature monitoring. Soil moisture, pH, and soil chemistry of the plots were also recorded. Data were analyzed using least absolute shrinkage and selection operator and linear regression to identify the environmental variable with the greatest influence on vegetation regeneration and root biomass. There was lower root biomass and slower vegetation regeneration in high temperature plots. Soil temperature was positively correlated with soil moisture and negatively correlated with soil pH. Iron and sulfate were present in the soil in the highest quantities compared to other measured soil chemicals and had a strong positive relationship with soil temperature. Our findings suggest that soil temperature had a major impact on root biomass and vegetation regeneration. In geothermal fields, vegetation establishment and growth can be restricted by low soil moisture, low soil pH, and an imbalance in soil chemistry. The correlation between soil moisture, pH, chemistry, and plant regeneration was chiefly driven by soil temperature. Soil temperature was negatively correlated to the distance from the geothermal features. Apart from characterizing plant regeneration on geothermal soils, this study further demonstrates a novel approach to global warming experiments, which could be particularly useful in low heat flow geothermal systems that more realistically mimic soil warming.

Conservatism of lizard thermal tolerances and body temperatures across evolutionary history and geography.

PubMed

Grigg, Joseph W; Buckley, Lauren B

2013-04-23

Species may exhibit similar thermal tolerances via either common ancestry or environmental filtering and local adaptation, if the species inhabit similar environments. We ask whether upper and lower thermal limits (critical thermal maxima and minima) and body temperatures are more strongly conserved across evolutionary history or geography for lizard populations distributed globally. We find that critical thermal maxima are highly conserved with location accounting for a higher proportion of the variation than phylogeny. Notably, thermal tolerance breadth is conserved across the phylogeny despite critical thermal minima showing little niche conservatism. Body temperatures observed during activity in the field show the greatest degree of conservatism, with phylogeny accounting for most of the variation. This suggests that propensities for thermoregulatory behaviour, which can buffer body temperatures from environmental variation, are similar within lineages. Phylogeny and geography constrain thermal tolerances similarly within continents, but variably within clades. Conservatism of thermal tolerances across lineages suggests that the potential for local adaptation to alleviate the impacts of climate change on lizards may be limited.

Caribbean coral growth influenced by anthropogenic aerosol emissions

NASA Astrophysics Data System (ADS)

Kwiatkowski, Lester; Cox, Peter M.; Economou, Theo; Halloran, Paul R.; Mumby, Peter J.; Booth, Ben B. B.; Carilli, Jessica; Guzman, Hector M.

2013-05-01

Coral growth rates are highly dependent on environmental variables such as sea surface temperature and solar irradiance. Multi-decadal variability in coral growth rates has been documented throughout the Caribbean over the past 150-200 years, and linked to variations in Atlantic sea surface temperatures. Multi-decadal variability in sea surface temperatures in the North Atlantic, in turn, has been linked to volcanic and anthropogenic aerosol forcing. Here, we examine the drivers of changes in coral growth rates in the western Caribbean between 1880 and 2000, using previously published coral growth chronologies from two sites in the region, and a numerical model. Changes in coral growth rates over this period coincided with variations in sea surface temperature and incoming short-wave radiation. Our model simulations show that variations in the concentration of anthropogenic aerosols caused variations in sea surface temperature and incoming radiation in the second half of the twentieth century. Before this, variations in volcanic aerosols may have played a more important role. With the exception of extreme mass bleaching events, we suggest that neither climate change from greenhouse-gas emissions nor ocean acidification is necessarily the driver of multi-decadal variations in growth rates at some Caribbean locations. Rather, the cause may be regional climate change due to volcanic and anthropogenic aerosol emissions.

Environmental physiology of a small marsupial inhabiting arid floodplains.

PubMed

Warnecke, L; Cooper, C E; Geiser, F; Withers, P C

2010-09-01

Giles' planigale (Planigale gilesi) is among the smallest extant marsupials and inhabits deep soil cracks in arid floodplains. We examined whether its physiology shows specific adaptations to its extreme habitat. Metabolic rate, body temperature, evaporative water loss and thermal conductance were measured for eight planigales (average mass 9 g) exposed to four different ambient temperatures ranging from 10 degrees C to 32 degrees C. Water economy and respiratory variables were measured for the first time in this species. All of these standard physiological variables conformed to allometrically-predicted values for a marsupial. All variables were significantly affected by ambient temperature, except tidal volume and dry thermal conductance. Metabolic rate increased substantially at low ambient temperatures, as required to maintain a relatively constant body temperature of about 32-34 degrees C. This increased oxygen demand was accommodated by increased ventilation rather than increased oxygen extraction. Planigales had a comparatively high point of relative water economy of 19.1 degrees C, consistent with their small body size and arid habitat. Torpor reduced energy expenditure by 79% and evaporative water loss by 62%. Our study suggests that torpor use, along with behavioural adaptations, suffice for P. gilesi to live underground in arid habitats without further physiological adaptations. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Realized niche width of a brackish water submerged aquatic vegetation under current environmental conditions and projected influences of climate change.

PubMed

Kotta, Jonne; Möller, Tiia; Orav-Kotta, Helen; Pärnoja, Merli

2014-12-01

Little is known about how organisms might respond to multiple climate stressors and this lack of knowledge limits our ability to manage coastal ecosystems under contemporary climate change. Ecological models provide managers and decision makers with greater certainty that the systems affected by their decisions are accurately represented. In this study Boosted Regression Trees modelling was used to relate the cover of submerged aquatic vegetation to the abiotic environment in the brackish Baltic Sea. The analyses showed that the majority of the studied submerged aquatic species are most sensitive to changes in water temperature, current velocity and winter ice scour. Surprisingly, water salinity, turbidity and eutrophication have little impact on the distributional pattern of the studied biota. Both small and large scale environmental variability contributes to the variability of submerged aquatic vegetation. When modelling species distribution under the projected influences of climate change, all of the studied submerged aquatic species appear to be very resilient to a broad range of environmental perturbation and biomass gains are expected when seawater temperature increases. This is mainly because vegetation develops faster in spring and has a longer growing season under the projected climate change scenario. Copyright © 2014 Elsevier Ltd. All rights reserved.

Environmental factors controlling fluxes of dimethyl sulfide in a New Hampshire fen

NASA Technical Reports Server (NTRS)

Demello, William Zamboni; Hines, Mark E.

1992-01-01

The major environmental factors controlling fluxes of dimethyl sulfide (DMS) in a Sphagnum-dominated peatland were investigated in a poor fen in New Hampshire. DMS emissions from the surface of the peatland varied greatly over 24 hours and seasonally. Maximum DMS emissions occurred in summer with minima in the late fall. Temperature was the major environmental factor controlling these variabilities. There was also some evidence that the changes in water table height might have contributed to the seasonable variability in DMS emission. The influence of the water table was greater during periods of elevated temperature. DMS and MSH were the most abundant dissolved volatile sulfur compound (VSC) in the surface of the water table. Concentrations of dissolved VSC's varied with time and space throughout the fen. Dissolved MDS, MSH, and OCS in the surface of the water table were supersaturated with respect to their concentrations in the atmosphere suggesting that the peat surface was a source of VSC's in the peatland. VCS in peatlands seemed to be produced primarily by microbial processes in the anoxic surface layers of the peat rich in organic matter and inorganic sulfide. Sphagnum mosses were not a direct source of VSC's. However, they increased transport of DMS from the peat surface to the atmosphere.

A dynamic aerodynamic resistance approach to calculate high resolution sensible heat fluxes in urban areas

NASA Astrophysics Data System (ADS)

Crawford, Ben; Grimmond, Sue; Kent, Christoph; Gabey, Andrew; Ward, Helen; Sun, Ting; Morrison, William

2017-04-01

Remotely sensed data from satellites have potential to enable high-resolution, automated calculation of urban surface energy balance terms and inform decisions about urban adaptations to environmental change. However, aerodynamic resistance methods to estimate sensible heat flux (QH) in cities using satellite-derived observations of surface temperature are difficult in part due to spatial and temporal variability of the thermal aerodynamic resistance term (rah). In this work, we extend an empirical function to estimate rah using observational data from several cities with a broad range of surface vegetation land cover properties. We then use this function to calculate spatially and temporally variable rah in London based on high-resolution (100 m) land cover datasets and in situ meteorological observations. In order to calculate high-resolution QH based on satellite-observed land surface temperatures, we also develop and employ novel methods to i) apply source area-weighted averaging of surface and meteorological variables across the study spatial domain, ii) calculate spatially variable, high-resolution meteorological variables (wind speed, friction velocity, and Obukhov length), iii) incorporate spatially interpolated urban air temperatures from a distributed sensor network, and iv) apply a modified Monte Carlo approach to assess uncertainties with our results, methods, and input variables. Modeled QH using the aerodynamic resistance method is then compared to in situ observations in central London from a unique network of scintillometers and eddy-covariance measurements.

Historical Arctic Logbooks Provide Insights into Past Diets and Climatic Responses of Cod

PubMed Central

Townhill, Bryony L.; Maxwell, David; Engelhard, Georg H.; Simpson, Stephen D.; Pinnegar, John K.

2015-01-01

Gadus morhua (Atlantic cod) stocks in the Barents Sea are currently at levels not seen since the 1950s. Causes for the population increase last century, and understanding of whether such large numbers will be maintained in the future, are unclear. To explore this, we digitised and interrogated historical cod catch and diet datasets from the Barents Sea. Seventeen years of catch data and 12 years of prey data spanning 1930–1959 cover unexplored spatial and temporal ranges, and importantly capture the end of a previous warm period, when temperatures were similar to those currently being experienced. This study aimed to evaluate cod catch per unit effort and prey frequency in relation to spatial, temporal and environmental variables. There was substantial spatio-temporal heterogeneity in catches through the time series. The highest catches were generally in the 1930s and 1940s, although at some localities more cod were recorded late in the 1950s. Generalized Additive Models showed that environmental, spatial and temporal variables are all valuable descriptors of cod catches, with the highest occurring from 15–45°E longitude and 73–77°N latitude, at bottom temperatures between 2 and 4°C and at depths between 150 and 250 m. Cod diets were highly variable during the study period, with frequent changes in the relative frequencies of different prey species, particularly Mallotus villosus (capelin). Environmental variables were particularly good at describing the importance of capelin and Clupea harengus (herring) in the diet. These new analyses support existing knowledge about how the ecology of the region is controlled by climatic variability. When viewed in combination with more recent data, these historical relationships will be valuable in forecasting the future of Barents Sea fisheries, and in understanding how environments and ecosystems may respond. PMID:26331271

Control of thermal balance by a liquid circulating garment based on a mathematical representation of the human thermoregulatory system. Ph.D. Thesis - California Univ., Berkeley

NASA Technical Reports Server (NTRS)

Kuznetz, L. H.

1976-01-01

Test data and a mathematical model of the human thermoregulatory system were used to investigate control of thermal balance by means of a liquid circulating garment (LCG). The test data were derived from five series of experiments in which environmental and metabolic conditions were varied parametrically as a function of several independent variables, including LCG flowrate, LCG inlet temperature, net environmental heat exchange, surrounding gas ventilation rate, ambient pressure, metabolic rate, and subjective/obligatory cooling control. The resultant data were used to relate skin temperature to LCG water temperature and flowrate, to assess a thermal comfort band, to demonstrate the relationship between metabolic rate and LCG heat dissipation, and so forth. The usefulness of the mathematical model as a tool for data interpretation and for generation of trends and relationships among the various physiological parameters was also investigated and verified.

Multiple environmental factors regulate the expression of the carbohydrate-selective OprB porin of Pseudomonas aeruginosa.

PubMed

Adewoye, L O; Worobec, E A

1999-12-01

In response to low extracellular glucose concentration, Pseudomonas aeruginosa induces the expression of the outer membrane carbohydrate-selective OprB porin. The promoter region of the oprB gene was cloned into a lacZ transcriptional fusion vector, and the construct was mobilized into P. aeruginosa OprB-deficient strain, WW100, to evaluate additional environmental factors that influence OprB porin gene expression. Growth temperature, pH of the growth medium, salicylate concentration, and carbohydrate source were found to differentially influence porin expression. This expression pattern was compared to those of whole-cell [14C]glucose uptake under conditions of high osmolarity, ionicity, variable pH, growth temperatures, and carbohydrate source. These studies revealed that the high-affinity glucose transport genes are down-regulated by salicylic acid, differentially regulated by pH and temperature, and are specifically responsive to exogenous glucose induction.

A simple method to predict body temperature of small reptiles from environmental temperature.

PubMed

Vickers, Mathew; Schwarzkopf, Lin

2016-05-01

To study behavioral thermoregulation, it is useful to use thermal sensors and physical models to collect environmental temperatures that are used to predict organism body temperature. Many techniques involve expensive or numerous types of sensors (cast copper models, or temperature, humidity, radiation, and wind speed sensors) to collect the microhabitat data necessary to predict body temperatures. Expense and diversity of requisite sensors can limit sampling resolution and accessibility of these methods. We compare body temperature predictions of small lizards from iButtons, DS18B20 sensors, and simple copper models, in both laboratory and natural conditions. Our aim was to develop an inexpensive yet accurate method for body temperature prediction. Either method was applicable given appropriate parameterization of the heat transfer equation used. The simplest and cheapest method was DS18B20 sensors attached to a small recording computer. There was little if any deficit in precision or accuracy compared to other published methods. We show how the heat transfer equation can be parameterized, and it can also be used to predict body temperature from historically collected data, allowing strong comparisons between current and previous environmental temperatures using the most modern techniques. Our simple method uses very cheap sensors and loggers to extensively sample habitat temperature, improving our understanding of microhabitat structure and thermal variability with respect to small ectotherms. While our method was quite precise, we feel any potential loss in accuracy is offset by the increase in sample resolution, important as it is increasingly apparent that, particularly for small ectotherms, habitat thermal heterogeneity is the strongest influence on transient body temperature.

Physiological community ecology: variation in metabolic activity of ecologically important rocky intertidal invertebrates along environmental gradients.

PubMed

Dahlhoff, Elizabeth P; Stillman, Jonathon H; Menge, Bruce A

2002-08-01

Rocky intertidal invertebrates live in heterogeneous habitats characterized by steep gradients in wave activity, tidal flux, temperature, food quality and food availability. These environmental factors impact metabolic activity via changes in energy input and stress-induced alteration of energetic demands. For keystone species, small environmentally induced shifts in metabolic activity may lead to disproportionately large impacts on community structure via changes in growth or survival of these key species. Here we use biochemical indicators to assess how natural differences in wave exposure, temperature and food availability may affect metabolic activity of mussels, barnacles, whelks and sea stars living at rocky intertidal sites with different physical and oceanographic characteristics. We show that oxygen consumption rate is correlated with the activity of key metabolic enzymes (e.g., citrate synthase and malate dehydrogenase) for some intertidal species, and concentrations of these enzymes in certain tissues are lower for starved individuals than for those that are well fed. We also show that the ratio of RNA to DNA (an index of protein synthetic capacity) is highly variable in nature and correlates with short-term changes in food availability. We also observed striking patterns in enzyme activity and RNA/DNA in nature, which are related to differences in rocky intertidal community structure. Differences among species and habitats are most pronounced in summer and are linked to high nearshore productivity at sites favored by suspension feeders and to exposure to stressful low-tide air temperatures in areas of low wave splash. These studies illustrate the great promise of using biochemical indicators to test ecological models, which predict changes in community structure along environmental gradients. Our results also suggest that biochemical indices must be carefully validated with laboratory studies, so that the indicator selected is likely to respond to the environmental variables of interest.

Predicting the spatial and temporal distributions of marine fish species utilizing earth system data in a MaxEnt model framework

NASA Astrophysics Data System (ADS)

Wang, L.; Kerr, L. A.; Bridger, E.

2016-02-01

Changes in species distributions have been widely associated with climate change. Understanding how ocean temperatures influence species distributions is critical for elucidating the role of climate in ecosystem change as well as for forecasting how species may be distributed in the future. As such, species distribution modeling (SDM) is increasingly useful in marine ecosystems research, as it can enable estimation of the likelihood of encountering marine fish in space or time as a function of a set of environmental and ecosystem conditions. Many traditional SDM approaches are applied to species data collected through standardized methods that include both presence and absence records, but are incapable of using presence-only data, such as those collected from fisheries or through citizen science programs. Maximum entropy (MaxEnt) models provide promising tools as they can predict species distributions from incomplete information (presence-only data). We developed a MaxEnt framework to relate the occurrence records of several marine fish species (e.g. Atlantic herring, Atlantic mackerel, and butterfish) to environmental conditions. Environmental variables derived from remote sensing, such as monthly average sea surface temperature (SST), are matched with fish species data, and model results indicate the relative occurrence rate of the species as a function of the environmental variables. The results can be used to provide hindcasts of where species might have been in the past in relation to historical environmental conditions, nowcasts in relation to current conditions, and forecasts of future species distributions. In this presentation, we will assess the relative influence of several environmental factors on marine fish species distributions, and evaluate the effects of data coverage on these presence-only models. We will also discuss how the information from species distribution forecasts can support climate adaptation planning in marine fisheries.

Associations and dynamics of Vibrionaceae in the environment, from the genus to the population level

PubMed Central

Takemura, Alison F.; Chien, Diana M.; Polz, Martin F.

2013-01-01

The Vibrionaceae, which encompasses several potential pathogens, including V. cholerae, the causative agent of cholera, and V. vulnificus, the deadliest seafood-borne pathogen, are a well-studied family of marine bacteria that thrive in diverse habitats. To elucidate the environmental conditions under which vibrios proliferate, numerous studies have examined correlations with bulk environmental variables—e.g., temperature, salinity, nitrogen, and phosphate—and association with potential host organisms. However, how meaningful these environmental associations are remains unclear because data are fragmented across studies with variable sampling and analysis methods. Here, we synthesize findings about Vibrio correlations and physical associations using a framework of increasingly fine environmental and taxonomic scales, to better understand their dynamics in the wild. We first conduct a meta-analysis to determine trends with respect to bulk water environmental variables, and find that while temperature and salinity are generally strongly predictive correlates, other parameters are inconsistent and overall patterns depend on taxonomic resolution. Based on the hypothesis that dynamics may better correlate with more narrowly defined niches, we review evidence for specific association with plants, algae, zooplankton, and animals. We find that Vibrio are attached to many organisms, though evidence for enrichment compared to the water column is often lacking. Additionally, contrary to the notion that they flourish predominantly while attached, Vibrio can have, at least temporarily, a free-living lifestyle and even engage in massive blooms. Fine-scale sampling from the water column has enabled identification of such lifestyle preferences for ecologically cohesive populations, and future efforts will benefit from similar analysis at fine genetic and environmental sampling scales to describe the conditions, habitats, and resources shaping Vibrio dynamics. PMID:24575082

Climate and atmosphere simulator for experiments on ecological systems in changing environments.

PubMed

Verdier, Bruno; Jouanneau, Isabelle; Simonnet, Benoit; Rabin, Christian; Van Dooren, Tom J M; Delpierre, Nicolas; Clobert, Jean; Abbadie, Luc; Ferrière, Régis; Le Galliard, Jean-François

2014-01-01

Grand challenges in global change research and environmental science raise the need for replicated experiments on ecosystems subjected to controlled changes in multiple environmental factors. We designed and developed the Ecolab as a variable climate and atmosphere simulator for multifactor experimentation on natural or artificial ecosystems. The Ecolab integrates atmosphere conditioning technology optimized for accuracy and reliability. The centerpiece is a highly contained, 13-m(3) chamber to host communities of aquatic and terrestrial species and control climate (temperature, humidity, rainfall, irradiance) and atmosphere conditions (O2 and CO2 concentrations). Temperature in the atmosphere and in the water or soil column can be controlled independently of each other. All climatic and atmospheric variables can be programmed to follow dynamical trajectories and simulate gradual as well as step changes. We demonstrate the Ecolab's capacity to simulate a broad range of atmospheric and climatic conditions, their diurnal and seasonal variations, and to support the growth of a model terrestrial plant in two contrasting climate scenarios. The adaptability of the Ecolab design makes it possible to study interactions between variable climate-atmosphere factors and biotic disturbances. Developed as an open-access, multichamber platform, this equipment is available to the international scientific community for exploring interactions and feedbacks between ecological and climate systems.

High-temperature thermal destruction of poultry derived wastes for energy recovery in Australia.

PubMed

Florin, N H; Maddocks, A R; Wood, S; Harris, A T

2009-04-01

The high-temperature thermal destruction of poultry derived wastes (e.g., manure and bedding) for energy recovery is viable in Australia when considering resource availability and equivalent commercial-scale experience in the UK. In this work, we identified and examined the opportunities and risks associated with common thermal destruction techniques, including: volume of waste, costs, technological risks and environmental impacts. Typical poultry waste streams were characterised based on compositional analysis, thermodynamic equilibrium modelling and non-isothermal thermogravimetric analysis coupled with mass spectrometry (TG-MS). Poultry waste is highly variable but otherwise comparable with other biomass fuels. The major technical and operating challenges are associated with this variability in terms of: moisture content, presence of inorganic species and type of litter. This variability is subject to a range of parameters including: type and age of bird, and geographical and seasonal inconsistencies. There are environmental and health considerations associated with combustion and gasification due to the formation of: NO(X), SO(X), H(2)S and HCl gas. Mitigation of these emissions is achievable through correct plant design and operation, however, with significant economic penalty. Based on our analysis and literature data, we present cost estimates for generic poultry-waste-fired power plants with throughputs of 2 and 8 tonnes/h.

Environmental Determinants of the Distribution of Chagas Disease Vector Triatoma dimidiata in Colombia.

PubMed

Parra-Henao, Gabriel; Quirós-Gómez, Oscar; Jaramillo-O, Nicolas; Cardona, Ángela Segura

2016-04-01

Triatoma dimidiata (Hemiptera: Reduviidae) is a secondary vector of Trypanosoma cruzi in Colombia and represents an important epidemiological risk mainly in the central and oriental regions of the country where it occupies sylvatic, peridomestic, and intradomestic ecotopes, and because of this complex distribution, its distribution and abundance could be conditioned by environmental factors. In this work, we explored the relationship between T. dimidiata distribution and environmental factors in the northwest, northeast, and central zones of Colombia and developed predictive models of infestation in the country. The associations between the presence ofT. dimidiata and environmental variables were studied using logistic regression models and ecological niche modeling for a sample of villages in Colombia. The analysis was based on the information collected in field about the presence ofT. dimidiata and the environmental data for each village extracted from remote sensing images. The presence of Triatoma dimidiata(Latreille, 1811) was found to be significantly associated with the maximum vegetation index, minimum land surface temperature (LST), and the digital elevation for the statistical model. Temperature seasonality, annual precipitation, and vegetation index were the variables that most influenced the ecological niche model ofT. dimidiata distribution. The logistic regression model showed a good fit and predicted suitable habitats in the Andean and Caribbean regions, which agrees with the known distribution of the species, but predicted suitable habitats in the Pacific and Orinoco regions proposing new areas of research. Improved models to predict suitable habitats forT. dimidiata hold promise for spatial targeting of integrated vector management. © The American Society of Tropical Medicine and Hygiene.

Environmental Determinants of the Distribution of Chagas Disease Vector Triatoma dimidiata in Colombia

PubMed Central

Parra-Henao, Gabriel; Quirós-Gómez, Oscar; Jaramillo-O, Nicolas; Cardona, Ángela Segura

2016-01-01

Triatoma dimidiata (Hemiptera: Reduviidae) is a secondary vector of Trypanosoma cruzi in Colombia and represents an important epidemiological risk mainly in the central and oriental regions of the country where it occupies sylvatic, peridomestic, and intradomestic ecotopes, and because of this complex distribution, its distribution and abundance could be conditioned by environmental factors. In this work, we explored the relationship between T. dimidiata distribution and environmental factors in the northwest, northeast, and central zones of Colombia and developed predictive models of infestation in the country. The associations between the presence of T. dimidiata and environmental variables were studied using logistic regression models and ecological niche modeling for a sample of villages in Colombia. The analysis was based on the information collected in field about the presence of T. dimidiata and the environmental data for each village extracted from remote sensing images. The presence of Triatoma dimidiata (Latreille, 1811) was found to be significantly associated with the maximum vegetation index, minimum land surface temperature (LST), and the digital elevation for the statistical model. Temperature seasonality, annual precipitation, and vegetation index were the variables that most influenced the ecological niche model of T. dimidiata distribution. The logistic regression model showed a good fit and predicted suitable habitats in the Andean and Caribbean regions, which agrees with the known distribution of the species, but predicted suitable habitats in the Pacific and Orinoco regions proposing new areas of research. Improved models to predict suitable habitats for T. dimidiata hold promise for spatial targeting of integrated vector management. PMID:26856910

Evidence for environmental and ecological selection in a microbe with no geographic limits to gene flow.

PubMed

Whittaker, Kerry A; Rynearson, Tatiana A

2017-03-07

The ability for organisms to disperse throughout their environment is thought to strongly influence population structure and thus evolution of diversity within species. A decades-long debate surrounds processes that generate and support high microbial diversity, particularly in the ocean. The debate concerns whether diversification occurs primarily through geographic partitioning (where distance limits gene flow) or through environmental selection, and remains unresolved due to lack of empirical data. Here we show that gene flow in a diatom, an ecologically important eukaryotic microbe, is not limited by global-scale geographic distance. Instead, environmental and ecological selection likely play a more significant role than dispersal in generating and maintaining diversity. We detected significantly diverged populations ( F ST > 0.130) and discovered temporal genetic variability at a single site that was on par with spatial genetic variability observed over distances of 15,000 km. Relatedness among populations was decoupled from geographic distance across the global ocean and instead, correlated significantly with water temperature and whole-community chlorophyll a Correlations with temperature point to the importance of environmental selection in structuring populations. Correlations with whole-community chlorophyll a , a proxy for autotrophic biomass, suggest that ecological selection via interactions with other plankton may generate and maintain population genetic structure in marine microbes despite global-scale dispersal. Here, we provide empirical evidence for global gene flow in a marine eukaryotic microbe, suggesting that everything holds the potential to be everywhere, with environmental and ecological selection rather than geography or dispersal dictating the structure and evolution of diversity over space and time.

Diurnal variability of regional cloud and clear-sky radiative parameters derived from GOES data. I - Analysis method. II - November 1978 cloud distributions. III - November 1978 radiative parameters

NASA Technical Reports Server (NTRS)

Minnis, P.; Harrison, E. F.

1984-01-01

Cloud cover is one of the most important variables affecting the earth radiation budget (ERB) and, ultimately, the global climate. The present investigation is concerned with several aspects of the effects of extended cloudiness, taking into account hourly visible and infrared data from the Geostationary Operational Environmental Satelite (GOES). A methodology called the hybrid bispectral threshold method is developed to extract regional cloud amounts at three levels in the atmosphere, effective cloud-top temperatures, clear-sky temperature and cloud and clear-sky visible reflectance characteristics from GOES data. The diurnal variations are examined in low, middle, high, and total cloudiness determined with this methodology for November 1978. The bulk, broadband radiative properties of the resultant cloud and clear-sky data are estimated to determine the possible effect of the diurnal variability of regional cloudiness on the interpretation of ERB measurements.

Hydrologic-energy balance constraints on the Holocene lake-level history of lake Titicaca, South America

NASA Astrophysics Data System (ADS)

Rowe, H. D.; Dunbar, R. B.

2004-09-01

A basin-scale hydrologic-energy balance model that integrates modern climatological, hydrological, and hypsographic observations was developed for the modern Lake Titicaca watershed (northern Altiplano, South America) and operated under variable conditions to understand controls on post-glacial changes in lake level. The model simulates changes in five environmental variables (air temperature, cloud fraction, precipitation, relative humidity, and land surface albedo). Relatively small changes in three meteorological variables (mean annual precipitation, temperature, and/or cloud fraction) explain the large mid-Holocene lake-level decrease (˜85 m) inferred from seismic reflection profiling and supported by sediment-based paleoproxies from lake sediments. Climatic controls that shape the present-day Altiplano and the sediment-based record of Holocene lake-level change are combined to interpret model-derived lake-level simulations in terms of changes in the mean state of ENSO and its impact on moisture transport to the Altiplano.

Mesocosms of aquatic bacterial communities from the Cuatro Cienegas Basin (Mexico): a tool to test bacterial community response to environmental stress.

PubMed

Pajares, Silvia; Bonilla-Rosso, German; Travisano, Michael; Eguiarte, Luis E; Souza, Valeria

2012-08-01

Microbial communities are responsible for important ecosystem processes, and their activities are regulated by environmental factors such as temperature and solar ultraviolet radiation. Here we investigate changes in aquatic microbial community structure, diversity, and evenness in response to changes in temperature and UV radiation. For this purpose, 15 mesocosms were seeded with both microbial mat communities and plankton from natural pools within the Cuatro Cienegas Basin (Mexico). Clone libraries (16S rRNA) were obtained from water samples at the beginning and at the end of the experiment (40 days). Phylogenetic analysis indicated substantial changes in aquatic community composition and structure in response to temperature and UV radiation. Extreme treatments with elevation in temperature or UV radiation reduced diversity in relation to the Control treatments, causing a reduction in richness and increase in dominance, with a proliferation of a few resistant operational taxonomic units. Each phylum was affected differentially by the new conditions, which translates in a differential modification of ecosystem functioning. This suggests that the impact of environmental stress, at least at short term, will reshape the aquatic bacterial communities of this unique ecosystem. This work also demonstrates the possibility of designing manageable synthetic microbial community ecosystems where controlled environmental variables can be manipulated. Therefore, microbial model systems offer a complementary approach to field and laboratory studies of global research problems associated with the environment.

Association of digital cushion thickness with sole temperature measured with the use of infrared thermography.

PubMed

Oikonomou, G; Trojacanec, P; Ganda, E K; Bicalho, M L S; Bicalho, R C

2014-07-01

The main objective of this study was to investigate the association between digital cushion thickness and sole temperature measured by infrared thermography. Data were collected from 216 lactating Holstein cows at 4 to 10d in milk (DIM). Cows were locomotion scored and sole temperature was measured after claw trimming (a minimum delay of 3 min was allowed for the hoof to cool) using an infrared thermography camera. Temperature was measured at the typical ulcer site of the lateral digit of the left hind foot. Immediately after the thermographic image was obtained, the thickness of the digital cushion was measured by ultrasonography. Rumen fluid samples were collected with a stomach tube and sample pH was measured immediately after collection. Additionally, a blood sample was obtained and used for measurements of serum concentrations of β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and haptoglobin. To evaluate the associations of digital cushion thickness with sole temperature, a linear regression model was built using the GLIMMIX procedure in SAS software (SAS Institute Inc., Cary, NC). Sole temperature was the response variable, and digital cushion thickness quartiles, locomotion score group, rumen fluid pH, rumen fluid sample volume, environmental temperature, age in days, and serum levels of NEFA, BHBA, and haptoglobin were fitted in the model. Only significant variables were retained in the final model. Simple linear regression scatter plots were used to illustrate associations between sole temperature (measured by infrared thermography at the typical ulcer site) and environmental temperature and between NEFA and BHBA serum levels and haptoglobin. One-way ANOVA was used to compare rumen fluid pH for different locomotion score groups and for different digital cushion quartiles. Results from the multivariable linear regression model showed that sole temperature increased as locomotion scores increased and decreased as digital cushion thickness increased. These results were adjusted for environmental temperature, which was significantly associated with sole temperature. Serum levels of NEFA, BHBA, and haptoglobin were not associated with sole temperature. However, significant correlations existed between serum levels of NEFA and haptoglobin and between serum levels of BHBA and haptoglobin. Rumen fluid pH was not associated with either locomotion score or digital cushion thickness. In conclusion, we show here that digital cushion thickness was associated with sole temperature in cows at 4 to 10 DIM. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The use of auxiliary variables in capture-recapture and removal experiments

USGS Publications Warehouse

Pollock, K.H.; Hines, J.E.; Nichols, J.D.

1984-01-01

The dependence of animal capture probabilities on auxiliary variables is an important practical problem which has not been considered in the development of estimation procedures for capture-recapture and removal experiments. In this paper the linear logistic binary regression model is used to relate the probability of capture to continuous auxiliary variables. The auxiliary variables could be environmental quantities such as air or water temperature, or characteristics of individual animals, such as body length or weight. Maximum likelihood estimators of the population parameters are considered for a variety of models which all assume a closed population. Testing between models is also considered. The models can also be used when one auxiliary variable is a measure of the effort expended in obtaining the sample.

Natural CMT2 Variation Is Associated With Genome-Wide Methylation Changes and Temperature Seasonality

PubMed Central

Shen, Xia; De Jonge, Jennifer; Forsberg, Simon K. G.; Pettersson, Mats E.; Sheng, Zheya; Hennig, Lars; Carlborg, Örjan

2014-01-01

As Arabidopsis thaliana has colonized a wide range of habitats across the world it is an attractive model for studying the genetic mechanisms underlying environmental adaptation. Here, we used public data from two collections of A. thaliana accessions to associate genetic variability at individual loci with differences in climates at the sampling sites. We use a novel method to screen the genome for plastic alleles that tolerate a broader climate range than the major allele. This approach reduces confounding with population structure and increases power compared to standard genome-wide association methods. Sixteen novel loci were found, including an association between Chromomethylase 2 (CMT2) and temperature seasonality where the genome-wide CHH methylation was different for the group of accessions carrying the plastic allele. Cmt2 mutants were shown to be more tolerant to heat-stress, suggesting genetic regulation of epigenetic modifications as a likely mechanism underlying natural adaptation to variable temperatures, potentially through differential allelic plasticity to temperature-stress. PMID:25503602

Temporal variability in chlorophyll fluorescence of back-reef corals in Ofu, American Samoa

USGS Publications Warehouse

Piniak, G.A.; Brown, E.K.

2009-01-01

Change in the yield of chlorophyll a fluorescence is a common indicator of thermal stress in corals. The present study reports temporal variability in quantum yield measurements for 10 coral species in Ofu, American Samoa - a place known to experience elevated and variable seawater temperatures. In winter, the zooxanthellae generally had higher dark-adapted maximum quantum yield (F v/Fm), higher light- adapted effective quantum yield (??F/F'm), and lower relative electron transport rates (rETR) than in the summer. Temporal changes appeared unrelated to the expected bleaching sensitivity of corals. All species surveyed, with the exception of Montipora grisea, demonstrated significant temporal changes in the three fluorescence parameters. Fluorescence responses were influenced by the microhabitat - temporal differences in fluorescence parameters were usually observed in the habitat with a more variable temperature regime (pool 300), while differences in Fv/Fm between species were observed only in the more environmentally stable habitat (pool 400). Such species-specific responses and microhabitat variability should be considered when attempting to determine whether observed in situ changes are normal seasonal changes or early signs of bleaching. ?? 2009 Marine Biological Laboratory.

Environmental links to interannual variability in shellfish toxicity in Cobscook Bay and eastern Maine, a strongly tidally mixed coastal region

NASA Astrophysics Data System (ADS)

Horecka, Hannah M.; Thomas, Andrew C.; Weatherbee, Ryan A.

2014-05-01

The Gulf of Maine experiences annual closures of shellfish harvesting due to the accumulation of toxins produced by dinoflagellates of the genus Alexandrium. Factors controlling the timing, location, and magnitude of these events in eastern Maine remain poorly understood. Previous work identified possible linkages between interannual variability of oceanographic variables and shellfish toxicity along the western Maine coastline but no such linkages were evident along the eastern Maine coast in the vicinity of Cobscook Bay, where strong tidal mixing tends to reduce seasonal variability in oceanographic properties. Using 21 years (1985-2005) of shellfish toxicity data, interannual variability in two metrics of annual toxicity, maximum magnitude and total annual toxicity, from stations in the Cobscook Bay region are examined for relationships to a suite of available environmental variables. Consistent with earlier work, no (or only weak) correlations were found between toxicity and oceanographic variables, even those very proximate to the stations such as local sea surface temperature. Similarly no correlations were evident between toxicity and air temperature, precipitation or relative humidity. The data suggest possible connections to local river discharge, but plausible mechanisms are not obvious. Correlations between toxicity and two variables indicative of local meteorological conditions, dew point and atmospheric pressure, both suggest a link between increased toxicity in these eastern Maine stations and weather conditions characterized by clearer skies/drier air (or less stormy/humid conditions). As no correlation of opposite sign was evident between toxicity and local precipitation, one plausible link is through light availability and its positive impact on phytoplankton production in this persistently foggy section of coast. These preliminary findings point to both the value of maintaining long-term shellfish toxicity sampling and a need for inclusion of weather variability in future modeling studies aimed at development of a more mechanistic understanding of factors controlling interannual differences in eastern Gulf of Maine shellfish toxicity.

Development of a winter wheat adjustable crop calendar model. [Colorado, Idaho, Oklahoma, Montana, Kansas, Missouri, North Dakota and Texas

NASA Technical Reports Server (NTRS)

Baker, J. R. (Principal Investigator)

1979-01-01

The author has identified the following significant results. Least squares techniques were applied for parameter estimation of functions to predict winter wheat phenological stage with daily maximum temperature, minimum temperature, daylength, and precipitation as independent variables. After parameter estimation, tests were conducted using independent data. It may generally be concluded that exponential functions have little advantage over polynomials. Precipitation was not found to significantly affect the fits. The Robertson triquadratic form, in general use for spring wheat, yielded good results, but special techniques and care are required. In most instances, equations with nonlinear effects were found to yield erratic results when utilized with averaged daily environmental values as independent variables.

A field study of the ventilatory response to ambient temperature and pressure in sport diving.

PubMed Central

Muller, F L

1995-01-01

This study reports on the relationship between minute ventilation (VE) and environmental variables of temperature (T) and pressure (P) during open water diving. The author conducted a total of 38 dives involving either a light (20 dives) or a moderate (18 dives) level of physical activity. Within each of these groups, P and T taken together accounted for about two thirds of the variance in the VE data. A very significant increase in VE was observed as T decreased (1 < T(degrees C) < 22), and the magnitude of this increase at a given pressure level was similar in the 'light' and the 'moderate' data sets. A second order observation, particularly notable at lower temperature, was the decrease in VE with increasing pressure under conditions of light work. Empirical functions of the from VE = A+B/P n[1 + exp(T - 8)/10], where A, B, and n are adjustable variables, could accommodate both data sets over the whole range of T and P. These results are the first obtained under actual diving conditions to provide evidence for interactions between P, T, and VE. Understanding the physiological mechanisms by which these interactions occur would assist in appreciation of the limitations imposed on scuba divers by the environmental conditions as they affect their ventilatory responses. PMID:8800853

Mitigating Harmful Cyanobacterial Blooms in a Human- and Climatically-Impacted World

PubMed Central

Paerl, Hans W.

2014-01-01

Bloom-forming harmful cyanobacteria (CyanoHABs) are harmful from environmental, ecological and human health perspectives by outcompeting beneficial phytoplankton, creating low oxygen conditions (hypoxia, anoxia), and by producing cyanotoxins. Cyanobacterial genera exhibit optimal growth rates and bloom potentials at relatively high water temperatures; hence, global warming plays a key role in their expansion and persistence. CyanoHABs are regulated by synergistic effects of nutrient (nitrogen:N and phosphorus:P) supplies, light, temperature, vertical stratification, water residence times, and biotic interactions. In most instances, nutrient control strategies should focus on reducing both N and P inputs. Strategies based on physical, chemical (nutrient) and biological manipulations can be effective in reducing CyanoHABs; however, these strategies are largely confined to relatively small systems, and some are prone to ecological and environmental drawbacks, including enhancing release of cyanotoxins, disruption of planktonic and benthic communities and fisheries habitat. All strategies should consider and be adaptive to climatic variability and change in order to be effective for long-term control of CyanoHABs. Rising temperatures and greater hydrologic variability will increase growth rates and alter critical nutrient thresholds for CyanoHAB development; thus, nutrient reductions for bloom control may need to be more aggressively pursued in response to climatic changes globally. PMID:25517134

MLP based LOGSIG transfer function for solar generation monitoring

NASA Astrophysics Data System (ADS)

Hashim, Fakroul Ridzuan; Din, Muhammad Faiz Md; Ahmad, Shahril; Arif, Farah Khairunnisa; Rizman, Zairi Ismael

2018-02-01

Solar panel is one of the renewable energy that can reduce the environmental pollution and have a wide potential of application. The exact solar prediction model will give a big impact on the management of solar power plants and the design of solar energy systems. This paper attempts to use Multilayer Perceptron (MLP) neural network based transfer function. The MLP network can be used to calculate the temperature module (TM) in Malaysia. This can be done by simulating the collected data of four weather variables which are the ambient temperature (TA), local wind speed (VW), solar radiation flux (GT) and the relative humidity (RH) as the input into the neural network. The transfer function will be applied to the 14 types of training. Finally, an equation from the best training algorithm will be deduced to calculate the temperature module based on the input of weather variables in Malaysia.

The effects of daily weather variables on psychosis admissions to psychiatric hospitals

NASA Astrophysics Data System (ADS)

McWilliams, Stephen; Kinsella, Anthony; O'Callaghan, Eadbhard

2013-07-01

Several studies have noted seasonal variations in admission rates of patients with psychotic illnesses. However, the changeable daily meteorological patterns within seasons have never been examined in any great depth in the context of admission rates. A handful of small studies have posed interesting questions regarding a potential link between psychiatric admission rates and meteorological variables such as environmental temperature (especially heat waves) and sunshine. In this study, we used simple non-parametric testing and more complex ARIMA and time-series regression analysis to examine whether daily meteorological patterns (wind speed and direction, barometric pressure, rainfall, sunshine, sunlight and temperature) exert an influence on admission rates for psychotic disorders across 12 regions in Ireland. Although there were some weak but interesting trends for temperature, barometric pressure and sunshine, the meteorological patterns ultimately did not exert a clinically significant influence over admissions for psychosis. Further analysis is needed.

Zebrafish take their cue from temperature but not photoperiod for the seasonal plasticity of thermal performance.

PubMed

Condon, Catriona H; Chenoweth, Stephen F; Wilson, Robbie S

2010-11-01

Organisms adjust to seasonal variability in the environment by responding to cues that indicate environmental change. As most studies of seasonal phenotypic plasticity test only the effect of a single environmental cue, how animals may integrate information from multiple cues to fine-tune plastic responses remains largely unknown. We examined the interaction between correlated (seasonally matching) and conflicting (seasonally opposite) temperature and photoperiod cues on the acclimation of performance traits in male zebrafish, Danio rerio. We acclimated fish for 8 weeks and then tested the change in thermal dependence of maximum burst swimming and feeding rate between 8 and 38°C. We predicted that correlated environmental cues should induce a greater acclimation response than uncorrelated cues. However, we found that only temperature was important for the seasonal acclimation of performance traits in zebrafish. Thermal acclimation shifted the thermal performance curve of both traits. For maximum burst swimming, performance increased for each group near the acclimation temperature and reduced in environments that were far from their acclimation temperature. The feeding rate of cold-acclimated zebrafish was reduced across the test temperature range compared with that of warm-acclimated fish. Our study is the first that has found no effect of the covariation between temperature and photoperiod acclimation cues on locomotor performance in fishes. Our results support the intuitive idea that photoperiod may be a less important seasonal cue for animals living at lower latitudes.

Controls of picophytoplankton abundance and composition in a highly dynamic marine system, the Northern Alboran Sea (Western Mediterranean)

NASA Astrophysics Data System (ADS)

Amorim, Ana L.; León, Pablo; Mercado, Jesús M.; Cortés, Dolores; Gómez, Francisco; Putzeys, Sebastien; Salles, Soluna; Yebra, Lidia

2016-06-01

The Alboran Sea is a highly dynamic basin which exhibits a high spatio-temporal variability of hydrographic structures (e.g. fronts, gyres, coastal upwellings). This work compares the abundance and composition of picophytoplankton observed across the northern Alboran Sea among eleven cruises between 2008 and 2012 using flow cytometry. We evaluate the seasonal and longitudinal variability of picophytoplankton on the basis of the circulation regimes at a regional scale and explore the presence of cyanobacteria ecotypes in the basin. The maximal abundances obtained for Prochlorococcus, Synechococcus and picoeukaryotes (12.7 × 104, 13.9 × 104 and 8.6 × 104 cells mL- 1 respectively) were consistent with those reported for other adjacent marine areas. Seasonal changes in the abundance of the three picophytoplankton groups were highly significant although they did not match the patterns described for other coastal waters. Higher abundances of Prochlorococcus were obtained in autumn-winter while Synechococcus and picoeukaryotes exhibited a different seasonal abundance pattern depending on the sector (e.g. Synechococcus showed higher abundance in summer in the west sector and during winter in the eastern study area). Additionally, conspicuous longitudinal gradients were observed for Prochlorococcus and Synechococcus, with Prochlorococcus decreasing from west to east and Synechococcus following the opposite pattern. The analysis of environmental variables (i.e. temperature, salinity and inorganic nutrients) and cell abundances indicates that Prochlorococcus preferred high salinity and nitrate to phosphate ratio. On the contrary, temperature did not seem to play a role in Prochlorococcus distribution as it was numerically important during the whole seasonal cycle. Variability in Synechococcus abundance could not be explained by changes in any environmental variable suggesting that different ecotypes were sampled during the surveys. In particular, our data would indicate the presence of at least two ecotypes of Synechococcus: a summer ecotype widely distributed in the whole Alboran Sea and a winter ecotype adapted to lower temperature and higher nutrient concentration whose growth is favoured in the eastern sector.

An investigation of a low-variability tire treadwear test procedure and of treadwear adjustment for ambient temperature. Volume 1 : the test procedures, statistical analyses, and the findings

DOT National Transportation Integrated Search

1985-01-01

The program was conducted to evaluate the variation in tire treadwear rates as : experienced on identical vehicles during the various environmental exposure : conditions of the winter, spring, and summer seasons. The diurnal/nocturnal effect : on the...

Human thermal comfort in urban outdoor spaces

Treesearch

Lee P. Herrington; J. S. Vittum

1977-01-01

Measurements of the physical environment of urban open spaces in Syracuse, New York, were used to compute the physiological responses of human users of the spaces. These calculations were then used to determine what environmental variables were both important to human comfort and susceptible to control by site design. Although air temperature and humidity are important...

Evaluating historical climate and hydrologic trends in the Central Appalachian region of the United States

NASA Astrophysics Data System (ADS)

Gaertner, B. A.; Zegre, N.

2015-12-01

Climate change is surfacing as one of the most important environmental and social issues of the 21st century. Over the last 100 years, observations show increasing trends in global temperatures and intensity and frequency of precipitation events such as flooding, drought, and extreme storms. Global circulation models (GCM) show similar trends for historic and future climate indicators, albeit with geographic and topographic variability at regional and local scale. In order to assess the utility of GCM projections for hydrologic modeling, it is important to quantify how robust GCM outputs are compared to robust historical observations at finer spatial scales. Previous research in the United States has primarily focused on the Western and Northeastern regions due to dominance of snow melt for runoff and aquifer recharge but the impact of climate warming in the mountainous central Appalachian Region is poorly understood. In this research, we assess the performance of GCM-generated historical climate compared to historical observations primarily in the context of forcing data for macro-scale hydrologic modeling. Our results show significant spatial heterogeneity of modeled climate indices when compared to observational trends at the watershed scale. Observational data is showing considerable variability within maximum temperature and precipitation trends, with consistent increases in minimum temperature. The geographic, temperature, and complex topographic gradient throughout the central Appalachian region is likely the contributing factor in temperature and precipitation variability. Variable climate changes are leading to more severe and frequent climate events such as temperature extremes and storm events, which can have significant impacts on our drinking water supply, infrastructure, and health of all downstream communities.

Application of Universal Thermal Climate Index (UTCI) for assessment of occupational heat stress in open-pit mines.

PubMed

Nassiri, Parvin; Monazzam, Mohammad Reza; Golbabaei, Farideh; Dehghan, Somayeh Farhang; Rafieepour, Athena; Mortezapour, Ali Reza; Asghari, Mehdi

2017-10-07

The purpose of this article is to examine the applicability of Universal Thermal Climate Index (UTCI) index as an innovative index for evaluating of occupational heat stress in outdoor environments. 175 workers of 12 open-pit mines in Tehran, Iran were selected for this research study. First, the environmental variables such as air temperature, wet-bulb temperature, globe temperature, relative humidity and air flow rate were measured; then UTCI, wet-bulb globe temperature (WBGT) and heat stress index (HSI) indices were calculated. Simultaneously, physiological parameters including heart rate, oral temperature, tympanic temperature and skin temperature of workers were measured. UTCI and WBGT are positively significantly correlated with all environmental parameters (p<0.03), except for air velocity (r<-0.39; p>0.05). Moreover, a strong significant relationship was found between UTCI and WBGT (r=0.95; p<0.001). The significant positive correlations exist between physiological parameters including oral temperature, tympanic and skin temperatures and heart rate and both the UTCI and WBGT indices (p<0.029). The highest correlation coefficient has been found between the UTCI and physiological parameters. Due to the low humidity and air velocity (~<1 m/s) in understudied mines, UTCI index appears to be appropriate to assess the occupational heat stress in these outdoor workplaces.

Assessment of surf zone environmental variables in a southwestern Atlantic sandy beach (Monte Hermoso, Argentina).

PubMed

Menéndez, M Clara; Fernández Severini, Melisa D; Buzzi, Natalia S; Piccolo, M Cintia; Perillo, Gerardo M E

2016-08-01

The aim of this study was to investigate the temporal dynamics (monthly/tidal) of water temperature, salinity, chlorophyll-a (chlo-a), suspended particulate matter (SPM), particulate organic carbon (POC), and dissolved nutrients in the surf zone of Monte Hermoso sandy beach, Argentina. We also aimed to understand the underlying mechanisms responsible for the observed variability. Sampling was carried out approximately monthly (September 2009-November 2010), and all samples were collected in a fixed station during high and low tide. Water temperature showed a clear seasonal variability (July: 9 °C-December: 26.5 °C) and a thermal amplitude of 17.5 °C. Salinity ranged from 33 to 37, without a pronounced seasonality. SPM (10-223 mg L(-1)) and POC concentrations (399-6445 mg C m(-3)) were high in surf zone waters. Chlo-a (0.05-9.16 μg L(-1)) was low and did not evidence the occurrence of surf diatom accumulations. Dissolved nutrient concentration was quite fluctuating. None of the variables seemed to be affected by tidal stage. The results showed how fluctuating the physico-chemical and biological variables can be in this particular system. The observed variability can be related with local beach conditions but also with regional processes. The study area is highly influenced by a neighbor estuary and as a consequence, could be vulnerable to their seasonal and inter-annual dynamics. All of these characteristics must be considered for further studies and planning of the uses of natural resources and should be taken into account in any environmental monitoring program conducted in a similar beach system.

Unravelling the architecture of functional variability in wild populations of Polygonum viviparum L

PubMed Central

Boucher, Florian C.; Thuiller, Wilfried; Arnoldi, Cindy; Albert, Cécile H.; Lavergne, Sébastien

2014-01-01

SUMMARY Functional variability (FV) of populations can be decomposed into three main features: the individual variability of multiple traits, the strength of correlations between those traits and the main direction of these correlations, the latter two being known as ‘phenotypic integration’. Evolutionary biology has long recognized that FV in natural populations is key to determining potential evolutionary responses, but this topic has been little studied in functional ecology. Here we focus on the arctico-alpine perennial plant species Polygonum viviparum L.. We used a comprehensive sampling of seven functional traits in 29 wild populations covering the whole environmental niche of the species. The niche of the species was captured by a temperature gradient, which separated alpine stressful habitats from species-rich, competitive sub-alpine ones. We seeked to assess the relative roles of abiotic stress and biotic interactions in shaping different aspects of functional variation within and among populations, that is, the multi-trait variability, the strength of correlations between traits, and the main directions of functional trade-offs. Populations with the highest extent of functional variability were found in the warm end of the gradient whereas populations exhibiting the strongest degree of phenotypic integration were located in sites with intermediate temperatures. This could reveal both the importance of environmental filtering and population demography in structuring FV. Interestingly, we found that the main axes of multivariate functional variation were radically different within and across population. Although the proximate causes of FV structure remain uncertain, our study presents a robust methodology for the quantitative study of functional variability in connection with species’ niches. It also opens up new perspectives for the conceptual merging of intraspecific functional patterns with community ecology. PMID:24790285

Inter-annual variability of North Sea plaice spawning habitat

NASA Astrophysics Data System (ADS)

Loots, C.; Vaz, S.; Koubbi, P.; Planque, B.; Coppin, F.; Verin, Y.

2010-11-01

Potential spawning habitat is defined as the area where environmental conditions are suitable for spawning to occur. Spawning adult data from the first quarter (January-March) of the International Bottom Trawl Survey have been used to study the inter-annual variability of the potential spawning habitat of North Sea plaice from 1980 to 2007. Generalised additive models (GAM) were used to create a model that related five environmental variables (depth, bottom temperature and salinity, seabed stress and sediment type) to presence-absence and abundance of spawning adults. Then, the habitat model was applied each year from 1970 to 2007 to predict inter-annual variability of the potential spawning habitat. Predicted responses obtained by GAM for each year were mapped using kriging. A hierarchical classification associated with a correspondence analysis was performed to cluster spawning suitable areas and to determine how they evolved across years. The potential spawning habitat was consistent with historical spawning ground locations described in the literature from eggs surveys. It was also found that the potential spawning habitat varied across years. Suitable areas were located in the southern part of the North Sea and along the eastern coast of England and Scotland in the eighties; they expanded further north from the nineties. Annual survey distributions did not show such northward expansion and remained located in the southern North Sea. This suggests that this species' actual spatial distribution remains stable against changing environmental conditions, and that the potential spawning habitat is not fully occupied. Changes in environmental conditions appear to remain within plaice environmental ranges, meaning that other factors may control the spatial distribution of plaice spawning habitat.

Short term effect of air pollution, noise and heat waves on preterm births in Madrid (Spain).

PubMed

Arroyo, Virginia; Díaz, Julio; Ortiz, Cristina; Carmona, Rocío; Sáez, Marc; Linares, Cristina

2016-02-01

Preterm birth (PTB) refers to delivery before 37 weeks of gestation and represents the leading cause of early-life mortality and morbidity in developed countries. PTB can lead to serious infant health outcomes. The etiology of PTB remains uncertain, but epidemiologic studies have consistently shown elevated risks with different environmental variables as traffic-related air pollution (TRAP). The aim of the study was to evaluate with time series methodology the short-term effect of air pollutants, noise levels and ambient temperature on the number of births and preterm births occurred in Madrid City during the 2001-2009 period. A time-series analysis was performed to assess the short term impact of daily mean concentrations (µg/m(3)) of PM2.5 and PM10, O3 and NO2. Measurements of Acoustic Pollution in dB(A) analyzed were: Leqd, equivalent diurnal noise level and Leqn, equivalent nocturnal noise level. Maximum and Minimum daily temperature (°C), mean Humidity in the air (%) and Atmospheric Pressure (HPa), were included too. Linear trends, seasonality, as well as the autoregressive nature of the series itself were controlled. We added as covariate the day of the week too. Autoregressive over-dispersed Poisson regression models were performed and the environmental variables were included with short-term lags (from 0 to 7 days) in reference to the date of birth. Firstly, simple models for the total number of births and preterm births were done separately. In a second stage, a model for total births adjusted for preterm births was performed. A total of 298,705 births were analyzed. The results of the final models were expressed in relative risks (RRs) for interquartile increase. We observed evidence of a short term effect at Lag 0, for the following environmental variables analyzed, PM2.5 (RR: 1.020; 95% CI:(1.008 1.032)) and O3 (RR: 1.012; 95% CI:(1.002 1.022)) concentrations and Leqd (RR: 1.139; 95% CI:( (1.124 1.154)) for the total number of births, and besides these, heat temperatures at Lag 1 (RR: 1.055; 95% CI:( (1.018 1.092)) on preterm births in Madrid City during the studied period. In the model adjusted for preterm births, similar RR was obtained for the same environmental variables. Especially PM2.5, diurnal noise levels and O3 have a short-term impact on total births and heat temperatures on preterm births in Madrid City during the studied period. Our results suggest that, given the widespread exposure of the population to the environmental factors analyzed and the possible effects on long-term health associated to low birth weight. There is a clear need to minimize this exposure through the decrease of air pollution and noise levels and through the behavior modification of the mothers. Copyright © 2015 Elsevier Inc. All rights reserved.

Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies

NASA Astrophysics Data System (ADS)

Jonkers, Lukas; Kučera, Michal

2017-06-01

The composition of planktonic foraminiferal (PF) calcite is routinely used to reconstruct climate variability. However, PF ecology leaves a large imprint on the proxy signal: seasonal and vertical habitats of PF species vary spatially, causing variable offsets from annual mean surface conditions recorded by sedimentary assemblages. PF seasonality changes with temperature in a way that minimises the environmental change that individual species experience and it is not unlikely that changes in depth habitat also result from such habitat tracking. While this behaviour could lead to an underestimation of spatial or temporal trends as well as of variability in proxy records, most palaeoceanographic studies are (implicitly) based on the assumption of a constant habitat. Up to now, the effect of habitat tracking on foraminifera proxy records has not yet been formally quantified on a global scale. Here we attempt to characterise this effect on the amplitude of environmental change recorded in sedimentary PF using core top δ18O data from six species. We find that the offset from mean annual near-surface δ18O values varies with temperature, with PF δ18O indicating warmer than mean conditions in colder waters (on average by -0.1 ‰ (equivalent to 0.4 °C) per °C), thus providing a first-order quantification of the degree of underestimation due to habitat tracking. We use an empirical model to estimate the contribution of seasonality to the observed difference between PF and annual mean δ18O and use the residual Δδ18O to assess trends in calcification depth. Our analysis indicates that given an observation-based model parametrisation calcification depth increases with temperature in all species and sensitivity analysis suggests that a temperature-related seasonal habitat adjustment is essential to explain the observed isotope signal. Habitat tracking can thus lead to a significant reduction in the amplitude of recorded environmental change. However, we show that this behaviour is predictable. This allows accounting for habitat tracking, enabling more meaningful reconstructions and improved data-model comparison.

Sediment microbial activity and its relation to environmental variables along the eastern Gulf of Finland coastline

NASA Astrophysics Data System (ADS)

Polyak, Yulia; Shigaeva, Tatyana; Gubelit, Yulia; Bakina, Ludmila; Kudryavtseva, Valentina; Polyak, Mark

2017-07-01

Sediment microbial activity and its relationship with the main environmental factors and pollutants were examined in the coastal area of the eastern Gulf of Finland, Baltic Sea. The activity of two common oxidoreductase enzymes: dehydrogenase (DA) and catalase (CA) varied significantly between 13 study sites. In the Neva Bay the highest microbial activities (DA: 2.64 mg TFF (10 g- 1) day- 1, CA: 6.29 mg H2O2 g- 1) were recorded, while in the outer estuary the minimum values of dehydrogenase and catalase were measured. DA, CA, and abundances of culturable heterotrophic bacteria (CHB) were positively correlated with each other, while biomass of green opportunistic algae was independent of both microbial activities and CHB. Enzymatic activity was found to be strongly positively correlated with sediment particle size and organic matter content, but unrelated to the other studied environmental parameters (temperature, pH, and salinity). Principal components analysis (PCA), controlling for environmental variables, supported direct effects of metal and oil contamination on sediment microbial activity. Also it had shown the similar patterns for algal biomass and metals. Our results suggest that copper and hydrocarbons are the main anthropogenic variables influencing enzyme distribution along the eastern Gulf of Finland coastline.

Design and evaluation of a bioreactor with application to forensic burial environments.

PubMed

Dunphy, Melissa A; Weisensee, Katherine E; Mikhailova, Elena A; Harman, Melinda K

2015-12-01

Existing forensic taphonomic methods lack specificity in estimating the postmortem interval (PMI) in the period following active decomposition. New methods, such as the use of citrate concentration in bone, are currently being considered; however, determining the applicability of these methods in differing environmental contexts is challenging. This research aims to design a forensic bioreactor that can account for environmental factors known to impact decomposition, specifically temperature, moisture, physical damage from animals, burial depth, soil pH, and organic matter content. These forensically relevant environmental variables were characterized in a soil science context. The resulting metrics were soil temperature regime, soil moisture regime, slope, texture, soil horizon, cation exchange capacity, soil pH, and organic matter content. Bioreactor chambers were constructed using sterilized thin-walled polystyrene boxes housed in calibrated temperature units. Gravesoil was represented using mineral soil (Ultisols), and organic soil proxy for Histosols, horticulture mix. Gravesoil depth was determined using mineral soil horizons A and Bt2 to simulate surface scatter and shallow grave burial respectively. A total of fourteen different environmental conditions were created and controlled successfully over a 90-day experiment. These results demonstrate successful implementation and control of forensic bioreactor simulating precise environments in a single research location, rather than site-specific testing occurring in different geographic regions. Bone sections were grossly assessed for weathering characteristics, which revealed notable differences related to exposure to different temperature regimes and soil types. Over the short 90-day duration of this experiment, changes in weathering characteristics were more evident across the different temperature regimes rather than the soil types. Using this methodology, bioreactor systems can be created to replicate many different clandestine burial contexts, which will allow for the more rapid understanding of environmental effects on skeletal remains. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Environmental correlates of upstream migration of yellow-phase American eels in the Potomac River drainage

USGS Publications Warehouse

Welsh, Stuart A.; Heather L. Liller,

2013-01-01

Assessing the relationships between upstream migration and environmental variables is important to understanding the ecology of yellow-phase American Eels Anguilla rostrata. During an American Eel migration study within the lower Shenandoah River (Potomac River drainage), we counted and measured American Eels at the Millville Dam eel ladder for three periods: 14 May–23 July 2004, 7–30 September 2004, and 1 June–31 July 2005. Using generalized estimating equations, we modeled each time series of daily American Eel counts by fitting time-varying environmental covariates of lunar illumination (LI), river discharge (RD), and water temperature (WT), including 1-d and 2-d lags of each covariate. Information-theoretic approaches were used for model selection and inference. A total of 4,847 American Eels (19–74 cm total length) used the ladder during the three periods, including 2,622 individuals during a 2-d span following a hurricane-induced peak in river discharge. Additive-effects models of RD + WT, a 2-d lag of LI + RD, and LI + RD were supported for the three periods, respectively. Parameter estimates were positive for river discharge for each time period, negative for lunar illumination for two periods and positive for water temperature during one period. Additive-effects models supported synergistic influences of environmental variables on the upstream migration of yellow-phase American Eels, although river discharge was consistently supported as an influential correlate of upstream migration.

Air temperature change in the northern and southern tropical Andes linked to North-Atlantic stadials and Greenland interstadials

NASA Astrophysics Data System (ADS)

Urrego, Dunia H.; Hooghiemstra, Henry

2016-04-01

We use eight pollen records reflecting climatic and environmental change from northern and southern sites in the tropical Andes. Our analysis focuses on the signature of millennial-scale climate variability during the last 30,000 years, in particular the Younger Dryas (YD), Heinrich stadials (HS) and Greenland interstadials (GI). We identify rapid responses of the vegetation to millennial-scale climate variability in the tropical Andes. The signature of HS and the YD are generally recorded as downslope migrations of the upper forest line (UFL), and are likely linked to air temperature cooling. The GI1 signal is overall comparable between northern and southern records and indicates upslope UFL migrations and warming in the tropical Andes. Our marker for lake level changes indicates a north to south difference that could be related to moisture availability. The direction of air temperature change recorded by the Andean vegetation is consistent with millennial-scale cryosphere and sea surface temperature records from the American tropics, but suggests a potential difference between the magnitude of temperature change in the ocean and the atmosphere.

Temporal dynamic of wood formation in Pinus cembra along the alpine treeline ecotone and the effect of climate variables

PubMed Central

Gruber, Andreas; Baumgartner, Daniel; Zimmermann, Jolanda; Oberhuber, Walter

2011-01-01

We determined the temporal dynamic of cambial activity and xylem development of stone pine (Pinus cembra L.) throughout the treeline ecotone. Repeated micro-sampling of the developing tree ring was carried out during the growing seasons 2006 and 2007 at the timberline (1950 m a.s.l.), treeline (2110 m a.s.l.) and within the krummholz belt (2180 m a.s.l.) and the influence of climate variables on intra-annual wood formation was determined. At the beginning of both growing seasons, highest numbers of cambial and enlarging cells were observed at the treeline. Soil temperatures at time of initiation of cambial activity were c. 1.5 °C higher at treeline (open canopy) compared to timberline (closed canopy), suggesting that a threshold root-zone temperature is involved in triggering onset of above ground stem growth. The rate of xylem cell production determined in two weekly intervals during June through August 2006-2007 was significantly correlated with air temperature (temperature sums expressed as degree-days and mean daily maximum temperature) at the timberline only. Lack of significant relationships between tracheid production and temperature variables at the treeline and within the krummholz belt support past dendroclimatological studies that more extreme environmental conditions (e.g., wind exposure, frost desiccation, late frost) increasingly control tree growth above timberline. Results of this study revealed that spatial and temporal (i.e. year-to-year) variability in timing and dynamic of wood formation of Pinus cembra is strongly influenced by local site factors within the treeline ecotone and the dynamics of seasonal temperature variation, respectively. PMID:21509148

High-resolution spatial databases of monthly climate variables (1961-2010) over a complex terrain region in southwestern China

NASA Astrophysics Data System (ADS)

Wu, Wei; Xu, An-Ding; Liu, Hong-Bin

2015-01-01

Climate data in gridded format are critical for understanding climate change and its impact on eco-environment. The aim of the current study is to develop spatial databases for three climate variables (maximum, minimum temperatures, and relative humidity) over a large region with complex topography in southwestern China. Five widely used approaches including inverse distance weighting, ordinary kriging, universal kriging, co-kriging, and thin-plate smoothing spline were tested. Root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) showed that thin-plate smoothing spline with latitude, longitude, and elevation outperformed other models. Average RMSE, MAE, and MAPE of the best models were 1.16 °C, 0.74 °C, and 7.38 % for maximum temperature; 0.826 °C, 0.58 °C, and 6.41 % for minimum temperature; and 3.44, 2.28, and 3.21 % for relative humidity, respectively. Spatial datasets of annual and monthly climate variables with 1-km resolution covering the period 1961-2010 were then obtained using the best performance methods. Comparative study showed that the current outcomes were in well agreement with public datasets. Based on the gridded datasets, changes in temperature variables were investigated across the study area. Future study might be needed to capture the uncertainty induced by environmental conditions through remote sensing and knowledge-based methods.

Spatial prediction of wheat Septoria leaf blotch (Septoria tritici) disease severity in central Ethiopia

USGS Publications Warehouse

Wakie, Tewodros; Kumar, Sunil; Senay, Gabriel; Takele, Abera; Lencho, Alemu

2016-01-01

A number of studies have reported the presence of wheat septoria leaf blotch (Septoria tritici; SLB) disease in Ethiopia. However, the environmental factors associated with SLB disease, and areas under risk of SLB disease, have not been studied. Here, we tested the hypothesis that environmental variables can adequately explain observed SLB disease severity levels in West Shewa, Central Ethiopia. Specifically, we identified 50 environmental variables and assessed their relationships with SLB disease severity. Geographically referenced disease severity data were obtained from the field, and linear regression and Boosted Regression Trees (BRT) modeling approaches were used for developing spatial models. Moderate-resolution imaging spectroradiometer (MODIS) derived vegetation indices and land surface temperature (LST) variables highly influenced SLB model predictions. Soil and topographic variables did not sufficiently explain observed SLB disease severity variation in this study. Our results show that wheat growing areas in Central Ethiopia, including highly productive districts, are at risk of SLB disease. The study demonstrates the integration of field data with modeling approaches such as BRT for predicting the spatial patterns of severity of a pathogenic wheat disease in Central Ethiopia. Our results can aid Ethiopia's wheat disease monitoring efforts, while our methods can be replicated for testing related hypotheses elsewhere.

Seasonality in cholera dynamics: A rainfall-driven model explains the wide range of patterns in endemic areas

NASA Astrophysics Data System (ADS)

Baracchini, Theo; King, Aaron A.; Bouma, Menno J.; Rodó, Xavier; Bertuzzo, Enrico; Pascual, Mercedes

2017-10-01

Seasonal patterns in cholera dynamics exhibit pronounced variability across geographical regions, showing single or multiple peaks at different times of the year. Although multiple hypotheses related to local climate variables have been proposed, an understanding of this seasonal variation remains incomplete. The historical Bengal region, which encompasses the full range of cholera's seasonality observed worldwide, provides a unique opportunity to gain insights on underlying environmental drivers. Here, we propose a mechanistic, rainfall-temperature driven, stochastic epidemiological model which explicitly accounts for the fluctuations of the aquatic reservoir, and analyze with this model the historical dataset of cholera mortality in the Bengal region. Parameters are inferred with a recently developed sequential Monte Carlo method for likelihood maximization in partially observed Markov processes. Results indicate that the hydrological regime is a major driver of the seasonal dynamics of cholera. Rainfall tends to buffer the propagation of the disease in wet regions due to the longer residence times of water in the environment and an associated dilution effect, whereas it enhances cholera resurgence in dry regions. Moreover, the dynamics of the environmental water reservoir determine whether the seasonality is unimodal or bimodal, as well as its phase relative to the monsoon. Thus, the full range of seasonal patterns can be explained based solely on the local variation of rainfall and temperature. Given the close connection between cholera seasonality and environmental conditions, a deeper understanding of the underlying mechanisms would allow the better management and planning of public health policies with respect to climate variability and climate change.

Identifying environmental determinants of diurnal distribution in marine birds and mammals.

PubMed

Henson, Shandelle M; Hayward, James L; Damania, Smruti P

2006-02-01

Marine birds and mammals move between various habitats during the day as they engage in behaviors related to resting, sleeping, preening, feeding, and breeding. The per capita rates of movement between these habitats, and hence the habitat occupancy dynamics, often are functions of environmental variables such as tide height, solar elevation, wind speed, and temperature. If the system recovers rapidly after disturbance, differential equation models of occupancy dynamics can be reduced to algebraic equations on two time scales. Identification of environmental factors that influence movement between habitats requires time series census data collected in both the absence and presence of disturbance.

Ecophysiological modeling of photosynthesis and carbon allocation to the tree stem in the boreal forest

NASA Astrophysics Data System (ADS)

Gennaretti, Fabio; Gea-Izquierdo, Guillermo; Boucher, Etienne; Berninger, Frank; Arseneault, Dominique; Guiot, Joel

2017-11-01

A better understanding of the coupling between photosynthesis and carbon allocation in the boreal forest, together with its associated environmental factors and mechanistic rules, is crucial to accurately predict boreal forest carbon stocks and fluxes, which are significant components of the global carbon budget. Here, we adapted the MAIDEN ecophysiological forest model to consider important processes for boreal tree species, such as nonlinear acclimation of photosynthesis to temperature changes, canopy development as a function of previous-year climate variables influencing bud formation and the temperature dependence of carbon partition in summer. We tested these modifications in the eastern Canadian taiga using black spruce (Picea mariana (Mill.) B.S.P.) gross primary production and ring width data. MAIDEN explains 90 % of the observed daily gross primary production variability, 73 % of the annual ring width variability and 20-30 % of its high-frequency component (i.e., when decadal trends are removed). The positive effect on stem growth due to climate warming over the last several decades is well captured by the model. In addition, we illustrate how we improve the model with each introduced model adaptation and compare the model results with those of linear response functions. Our results demonstrate that MAIDEN simulates robust relationships with the most important climate variables (those detected by classical response-function analysis) and is a powerful tool for understanding how environmental factors interact with black spruce ecophysiology to influence present-day and future boreal forest carbon fluxes.

Puffins reveal contrasting relationships between forage fish and ocean climate in the North Pacific

USGS Publications Warehouse

Sydeman, William J.; Piatt, John F.; Thompson, Sarah Ann; Garcia-Reyes, Marisol; Hatch, Scott A.; Arimitsu, Mayumi L.; Slater, Leslie; Williams, Jeffrey C.; Rojek, Nora A.; Zador, Stephani G.; Renner, Heather M.

2017-01-01

Long-term studies of predator food habits (i.e., ‘predator-based sampling’) are useful for identifying patterns of spatial and temporal variability of forage nekton in marine ecosystems. We investigated temporal changes in forage fish availability and relationships to ocean climate by analyzing diet composition of three puffin species (horned puffin Fratercula corniculata, tufted puffin Fratercula cirrhata, and rhinoceros auklet Cerorhinca monocerata) from five sites in the North Pacific from 1978–2012. Dominant forage species included squids and hexagrammids in the western Aleutians, gadids and Pacific sand lance (Ammodytes personatus) in the eastern Aleutians and western Gulf of Alaska (GoA), and sand lance and capelin (Mallotus villosus) in the northern and eastern GoA. Interannual fluctuations in forage availability dominated variability in the western Aleutians, whereas lower-frequency shifts in forage fish availability dominated elsewhere. We produced regional multivariate indicators of sand lance, capelin, and age-0 gadid availability by combining data across species and sites using Principal Component Analysis, and related these indices to environmental factors including sea level pressure (SPL), winds, and sea surface temperature (SST). There was coherence in the availability of sand lance and capelin across the study area. Sand lance availability increased linearly with environmental conditions leading to warmer ocean temperatures, whereas capelin availability increased in a non-linear manner when environmental changes led to lower ocean temperatures. Long-term studies of puffin diet composition appear to be a promising tool for understanding the availability of these difficult-to-survey forage nekton in remote regions of the North Pacific.

Endocrinology of year-round reproduction in a highly seasonal habitat: environmental variability in testosterone and glucocorticoids in baboon males

PubMed Central

Gesquiere, Laurence R.; Onyango, Patrick O.; Alberts, Susan C.; Altmann, Jeanne

2010-01-01

In conditions characterized by energetic constraints, such as in periods of low food availability, some trade-offs between reproduction and self-maintenance may be necessary; even year-round breeders may then be forced to exhibit some reproductive seasonality. Prior research has largely focused on female reproduction and physiology, and few studies have evaluated the impact of environmental factors on males. Here we assessed the effects of season and ambient temperatures on fecal glucocorticoid (fGC) and testosterone (fT) levels in male baboons in Amboseli, Kenya. The Amboseli basin is a highly challenging, semi-arid tropical habitat that is characterized by strongly seasonal patterns of rainfall and by high ambient temperatures. We previously reported that female baboons were impacted by these challenging environmental conditions. We ask here whether male baboons in the same environment and groups as females exhibit similar physiological effects. We found that after accounting for male age and individual variability, males exhibited higher fGC levels and lower fT levels during the dry season than during the wet season. Furthermore, fT but not fGC levels were lower in months of high average daily maximum temperatures, suggesting a direct impact of heat on testes. Our results demonstrate that male baboons, like females, experience ecological stress that alters their reproductive physiology. The impact of the environment on male reproduction deserves more attention both in its own right and because alteration in male physiology may contribute to the reduction in female fertility observed in challenging environments. PMID:20721938

Temperature-dependent, behavioural, and transcriptional variability of a tritrophic interaction consisting of bean, herbivorous mite, and predator.

PubMed

Ozawa, Rika; Nishimura, Osamu; Yazawa, Shigenobu; Muroi, Atsushi; Takabayashi, Junji; Arimura, Gen-ichiro

2012-11-01

Different organisms compensate for, and adapt to, environmental changes in different ways. In this way, environmental changes affect animal-plant interactions. In this study, we assessed the effect of temperature on a tritrophic system of the lima bean, the herbivorous spider mite Tetranychus urticae and the predatory mite Phytoseiulus persimilis. In this system, the plant defends itself against T. urticae by emitting volatiles that attract P. persimilis. Over 20-40 °C, the emission of volatiles by infested plants and the subsequent attraction of P. persimilis peaked at 30 °C, but the number of eggs laid by T. urticae adults and the number of eggs consumed by P. persimilis peaked at 35 °C. This indicates that the spider mites and predatory mites performed best at a higher temperature than that at which most volatile attractants were produced. Our data from transcriptome pyrosequencing of the mites found that P. persimilis up-regulated gene families for heat shock proteins (HSPs) and ubiquitin-associated proteins, whereas T. urticae did not. RNA interference-mediated gene suppression in P. persimilis revealed differences in temperature responses. Predation on T. urticae eggs by P. persimilis that had been fed PpHsp70-1 dsRNA was low at 35 °C but not at 25 °C when PpHsp70-1 expression was very high. Overall, our molecular and behavioural approaches revealed that the mode and tolerance of lima bean, T. urticae and P. persimilis are distinctly affected by temperature variability, thereby making their tritrophic interactions temperature dependent. © 2012 Blackwell Publishing Ltd.

Archaea in aquaria: Investigating the role of environmental influences on TEX86 in long-term culture experiments

NASA Astrophysics Data System (ADS)

Warren, C.; Pagani, M.

2016-12-01

The TEX86 paleotemperature proxy has experienced a recent rise in application, due in part to its capacity to estimate temperatures above 30°C, and to the ubiquity of the archaeal membrane lipids that comprise it. Studies comparing environmental influences and archaeal lipids - specifically core glycerol dibiphytanyl glycerol tetraethers (GDGTs) - offer insights into non-temperature influences on TEX86. Here we present environmental measurements and lipid distributions from >200 long-running aquarium systems using source water from North American coastal sites ranging in latitude from 60.12ºN to 24.56ºN. The influence of 32 environmental variables (depth, pH, etc.) was evaluated in the entire dataset, as well as in a subset that limited the influence of community structure. Based on multiple correlation analyses we demonstrate that temperature is the central factor influencing the distribution of core GDGTs in aquarium tanks, with the possible exception of GDGT-1, for which dissolved oxygen concentration is equivocally significant when GDGT-4 is included in the calculation of relative abundances. Temperature was found to have the most significant relationship with TEX86, with neither oxygen concentration nor water density making comparable contributions. Salinity, pH, and community structure have emerged as important, but less significant secondary influences of TEX86. Low salinity (<15 PSU) was consistently associated with TEX86 values that substantially overestimate tank temperature. The presence and abundance of MG-II Euryarchaeota, when considered, do not appear to significantly change the TEX86-temperature relationship. In addition, Illumina MiSeq 16S rDNA sequencing was used to assess whether archaeal communities differed along a spectrum of TEX86 values and environmental conditions. This technique allowed for the assessment of a taxonomically constrained subset of samples (n=54) where the archaeal tank populations were >98% sequences recognized as associated with the genus Nitrosopumilus (cultured ammonia oxidizers). In this dataset the relative abundance of GDGT-0 provided a better estimate of temperature than TEX86, and unusually high nitrite concentrations strongly correlated with underestimates of TEX86-based temperature relative to measured water temperature.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chicoine, T.K.; Fay, P.K.; Nielsen, G.A.

Soil characteristics, elevation, annual precipitation, potential evapotranspiration, length of frost-free season, and mean maximum July temperature were estimated for 116 established infestations of spotted knapweed (Centaurea maculosa Lam. number/sup 3/ CENMA) in Montana using basic land resource maps. Areas potentially vulnerable to invasion by the plant were delineated on the basis of representative edaphic and climatic characteristics. No single environmental variable was an effective predictor of sites vulnerable to invasion by spotted knapweed. Only a combination of variables was effective, indicating that the factors that regulate adaptability of this plant are complex. This technique provides a first approximation map ofmore » the regions most similar environmentally to infested sites and; therefore, most vulnerable to further invasion. This weed migration prediction technique shows promise for predicting suitable habitats of other invader species. 6 references, 4 figures, 1 table.« less

Thermal Imaging of Forest Canopy Temperatures: Relationships with Biological and Biophysical Drivers and Ecosystem Fluxes

NASA Astrophysics Data System (ADS)

Still, C. J.; Kim, Y.; Hanson, C. V.; Law, B. E.; Kwon, H.; Schulze, M.; Pau, S.; Detto, M.

2015-12-01

Temperature is a primary environmental control on plant processes at a range of spatial and temporal scales, affecting enzymatic reactions, ecosystem biogeochemistry, and species distributions. Although most focus is on air temperature, the radiative or skin temperature of plants is more relevant. Canopy skin temperature dynamics reflect biophysical, physiological, and anatomical characteristics and interactions with environmental drivers, and can be used to examine forest responses to stresses like droughts and heat waves. Direct measurements of plant canopy temperatures using thermocouple sensors have been challenging and offer limited information. Such measurements are usually conducted over short periods of time and a limited spatial extent of the canopy. By contrast, thermal infrared (TIR) imaging allows for extensive temporal and spatial measurement of canopy temperature regimes. We present results of TIR imaging of forest canopies at a range of well-studied forest sites in the United States and Panama. These forest types include temperate rainforests, a semi­arid pine forest, and a semi­deciduous tropical forest. Canopy temperature regimes at these sites are highly variable spatially and temporally and display frequent departures from air temperature, particularly during clear sky conditions. Canopy tissue temperatures are often warmer (daytime) and colder (nighttime) than air temperature, and canopy structure seems to have a large influence on the thermal regime. Additionally, comparison of canopy temperatures to eddy covariance fluxes of carbon dioxide, water vapor, and energy reveals relationships not apparent using air temperature. Initial comparisons between our forest canopy temperatures and remotely sensed skin temperature using Landsat and MODIS data show reasonably good agreement. We conclude that temporal and spatial changes in canopy temperature and its relationship to biological and environmental factors can improve our understanding of how climate change is affecting forest function, and argue for wider deployment of thermal cameras in other ecosystems.

The subtle intracapsular survival of the fittest: maternal investment, sibling conflict, or environmental effects?

PubMed

Smith, Kathryn E; Thatje, Sven

2013-10-01

Developmental resource partitioning and the consequent offspring size variations are of fundamental importance for marine invertebrates, in both an ecological and evolutionary context. Typically, differences are attributed to maternal investment and the environmental factors determining this; additional variables, such as environmental factors affecting development, are rarely discussed. During intracapsular development, for example, sibling conflict has the potential to affect resource partitioning. Here, we investigate encapsulated development in the marine gastropod Buccinum undatum. We examine the effects of maternal investment and temperature on intracapsular resource partitioning in this species. Reproductive output was positively influenced by maternal investment, but additionally, temperature and sibling conflict significantly affected offspring size, number, and quality during development. Increased temperature led to reduced offspring number, and a combination of high sibling competition and asynchronous early development resulted in a common occurrence of "empty" embryos, which received no nutrition at all. The proportion of empty embryos increased with both temperature and capsule size. Additionally, a novel example ofa risk in sibling conflict was observed; embryos cannibalized by others during early development ingested nurse eggs from inside the consumer, killing it in a "Trojan horse" scenario. Our results highlight the complexity surrounding offspring fitness. Encapsulation should be considered as significant in determining maternal output. Considering predicted increases in ocean temperatures, this may impact offspring quality and consequently species distribution and abundance.

Climate variability and environmental stress in the Sudan-Sahel zone of West Africa.

PubMed

Mertz, Ole; D'haen, Sarah; Maiga, Abdou; Moussa, Ibrahim Bouzou; Barbier, Bruno; Diouf, Awa; Diallo, Drissa; Da, Evariste Dapola; Dabi, Daniel

2012-06-01

Environmental change in the Sudan-Sahel region of West Africa (SSWA) has been much debated since the droughts of the 1970s. In this article we assess climate variability and environmental stress in the region. Households in Senegal, Mali, Burkina Faso, Niger, and Nigeria were asked about climatic changes and their perceptions were compared across north-south and west-east rainfall gradients. More than 80% of all households found that rainfall had decreased, especially in the wettest areas. Increases in wind speeds and temperature were perceived by an overall 60-80% of households. Contrary to household perceptions, observed rainfall patterns showed an increasing trend over the past 20 years. However, August rainfall declined, and could therefore potentially explain the contrasting negative household perceptions of rainfall trends. Most households reported degradation of soils, water resources, vegetation, and fauna, but more so in the 500-900 mm zones. Adaptation measures to counter environmental degradation included use of manure, reforestation, soil and water conservation, and protection of fauna and vegetation. The results raise concerns for future environmental management in the region, especially in the 500-900 mm zones and the western part of SSWA.

Integrated presentation of ecological risk from multiple stressors

PubMed Central

Goussen, Benoit; Price, Oliver R.; Rendal, Cecilie; Ashauer, Roman

2016-01-01

Current environmental risk assessments (ERA) do not account explicitly for ecological factors (e.g. species composition, temperature or food availability) and multiple stressors. Assessing mixtures of chemical and ecological stressors is needed as well as accounting for variability in environmental conditions and uncertainty of data and models. Here we propose a novel probabilistic ERA framework to overcome these limitations, which focusses on visualising assessment outcomes by construct-ing and interpreting prevalence plots as a quantitative prediction of risk. Key components include environmental scenarios that integrate exposure and ecology, and ecological modelling of relevant endpoints to assess the effect of a combination of stressors. Our illustrative results demonstrate the importance of regional differences in environmental conditions and the confounding interactions of stressors. Using this framework and prevalence plots provides a risk-based approach that combines risk assessment and risk management in a meaningful way and presents a truly mechanistic alternative to the threshold approach. Even whilst research continues to improve the underlying models and data, regulators and decision makers can already use the framework and prevalence plots. The integration of multiple stressors, environmental conditions and variability makes ERA more relevant and realistic. PMID:27782171

Short-term variability in labile soil phosphorus is positively related to soil moisture in a humid tropical forest in Puerto Rico

Treesearch

Tana E. Wood; Danielle Matthews; Karen Vandecar; Deborah Lawrence

2016-01-01

Primary productivity in tropical forests is often considered limited by phosphorus (P) availability. Microbial activity is a key regulator of available P through organic matter decomposition (supply) as well as microbial immobilization (depletion). Environmental conditions, such as soil moisture and temperature can fluctuate...

A northwest North American training set: distribution of freshwater midges in relation to air temperature and lake depth

Treesearch

Erin M. Barley; Ian R. Walker; Joshua Kurek; Les C. Cwynar; Rolf W. Mathewes; Konrad Gajewski; Bruce P. Finney

2006-01-01

Freshwater midges, consisting of Chironomidae, Chaoboridae, and Ceratopogonidae, were assessed as a biological proxy for palaeoclimate in eastern Beringia. The northwest North American training set consists of midge assemblages and data for 17 environmental variables collected from 145 lakes in Alaska, British Columbia, Yukon, Northwest Territories, and the Canadian...

Socio-environmental predictors of Barmah forest virus transmission in coastal areas, Queensland, Australia.

PubMed

Naish, Suchithra; Hu, Wenbiao; Nicholls, Neville; Mackenzie, John S; Dale, Pat; McMichael, Anthony J; Tong, Shilu

2009-02-01

To assess the socio-environmental predictors of Barmah forest virus (BFV) transmission in coastal areas, Queensland, Australia. Data on BFV notified cases, climate, tidal levels and socioeconomic index for area (SEIFA) in six coastal cities, Queensland, for the period 1992-2001 were obtained from the relevant government agencies. Negative binomial regression models were used to assess the socio-environmental predictors of BFV transmission. The results show that maximum and minimum temperature, rainfall, relative humidity, high and low tide were statistically significantly associated with BFV incidence at lags 0-2 months. The fitted negative binomial regression models indicate a significant independent association of each of maximum temperature (beta = 0.139, P = 0.000), high tide (beta = 0.005, P = 0.000) and SEIFA index (beta = -0.010, P = 0.000) with BFV transmission after adjustment for confounding variables. The transmission of BFV disease in Queensland coastal areas seemed to be determined by a combination of local social and environmental factors. The model developed in this study may have applications in the control and prevention of BFV disease in these areas.

Environmental factor analysis of cholera in China using remote sensing and geographical information systems.

PubMed

Xu, M; Cao, C X; Wang, D C; Kan, B; Xu, Y F; Ni, X L; Zhu, Z C

2016-04-01

Cholera is one of a number of infectious diseases that appears to be influenced by climate, geography and other natural environments. This study analysed the environmental factors of the spatial distribution of cholera in China. It shows that temperature, precipitation, elevation, and distance to the coastline have significant impact on the distribution of cholera. It also reveals the oceanic environmental factors associated with cholera in Zhejiang, which is a coastal province of China, using both remote sensing (RS) and geographical information systems (GIS). The analysis has validated the correlation between indirect satellite measurements of sea surface temperature (SST), sea surface height (SSH) and ocean chlorophyll concentration (OCC) and the local number of cholera cases based on 8-year monthly data from 2001 to 2008. The results show the number of cholera cases has been strongly affected by the variables of SST, SSH and OCC. Utilizing this information, a cholera prediction model has been established based on the oceanic and climatic environmental factors. The model indicates that RS and GIS have great potential for designing an early warning system for cholera.

Impact of climate change on cold hardiness of Douglas-fir (Pseudotsuga menziesii): environmental and genetic considerations.

PubMed

Bansal, Sheel; St Clair, J Bradley; Harrington, Constance A; Gould, Peter J

2015-10-01

The success of conifers over much of the world's terrestrial surface is largely attributable to their tolerance to cold stress (i.e., cold hardiness). Due to an increase in climate variability, climate change may reduce conifer cold hardiness, which in turn could impact ecosystem functioning and productivity in conifer-dominated forests. The expression of cold hardiness is a product of environmental cues (E), genetic differentiation (G), and their interaction (G × E), although few studies have considered all components together. To better understand and manage for the impacts of climate change on conifer cold hardiness, we conducted a common garden experiment replicated in three test environments (cool, moderate, and warm) using 35 populations of coast Douglas-fir (Pseudotsuga menziesii var. menziesii) to test the hypotheses: (i) cool-temperature cues in fall are necessary to trigger cold hardening, (ii) there is large genetic variation among populations in cold hardiness that can be predicted from seed-source climate variables, (iii) observed differences among populations in cold hardiness in situ are dependent on effective environmental cues, and (iv) movement of seed sources from warmer to cooler climates will increase risk to cold injury. During fall 2012, we visually assessed cold damage of bud, needle, and stem tissues following artificial freeze tests. Cool-temperature cues (e.g., degree hours below 2 °C) at the test sites were associated with cold hardening, which were minimal at the moderate test site owing to mild fall temperatures. Populations differed 3-fold in cold hardiness, with winter minimum temperatures and fall frost dates as strong seed-source climate predictors of cold hardiness, and with summer temperatures and aridity as secondary predictors. Seed-source movement resulted in only modest increases in cold damage. Our findings indicate that increased fall temperatures delay cold hardening, warmer/drier summers confer a degree of cold hardiness, and seed-source movement from warmer to cooler climates may be a viable option for adapting coniferous forest to future climate. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Structural Model for the Effects of Environmental Elements on the Psychological Characteristics and Performance of the Employees of Manufacturing Systems

PubMed Central

Realyvásquez, Arturo; Maldonado-Macías, Aidé Aracely; García-Alcaraz, Jorge; Cortés-Robles, Guillermo; Blanco-Fernández, Julio

2016-01-01

This paper analyzes the effects of environmental elements on the psychological characteristics and performance of employees in manufacturing systems using structural equation modeling. Increasing the comprehension of these effects may help optimize manufacturing systems regarding their employees’ psychological characteristics and performance from a macroergonomic perspective. As the method, a new macroergonomic compatibility questionnaire (MCQ) was developed and statistically validated, and 158 respondents at four manufacture companies were considered. Noise, lighting and temperature, humidity and air quality (THAQ) were used as independent variables and psychological characteristics and employees’ performance as dependent variables. To propose and test the hypothetical causal model of significant relationships among the variables, a data analysis was deployed. Results found that the macroergonomic compatibility of environmental elements presents significant direct effects on employees’ psychological characteristics and either direct or indirect effects on the employees’ performance. THAQ had the highest direct and total effects on psychological characteristics. Regarding the direct and total effects on employees’ performance, the psychological characteristics presented the highest effects, followed by THAQ conditions. These results may help measure and optimize manufacturing systems’ performance by enhancing their macroergonomic compatibility and quality of life at work of the employees. PMID:26742054

Structural Model for the Effects of Environmental Elements on the Psychological Characteristics and Performance of the Employees of Manufacturing Systems.

PubMed

Realyvásquez, Arturo; Maldonado-Macías, Aidé Aracely; García-Alcaraz, Jorge; Cortés-Robles, Guillermo; Blanco-Fernández, Julio

2016-01-05

This paper analyzes the effects of environmental elements on the psychological characteristics and performance of employees in manufacturing systems using structural equation modeling. Increasing the comprehension of these effects may help optimize manufacturing systems regarding their employees' psychological characteristics and performance from a macroergonomic perspective. As the method, a new macroergonomic compatibility questionnaire (MCQ) was developed and statistically validated, and 158 respondents at four manufacture companies were considered. Noise, lighting and temperature, humidity and air quality (THAQ) were used as independent variables and psychological characteristics and employees' performance as dependent variables. To propose and test the hypothetical causal model of significant relationships among the variables, a data analysis was deployed. Results found that the macroergonomic compatibility of environmental elements presents significant direct effects on employees' psychological characteristics and either direct or indirect effects on the employees' performance. THAQ had the highest direct and total effects on psychological characteristics. Regarding the direct and total effects on employees' performance, the psychological characteristics presented the highest effects, followed by THAQ conditions. These results may help measure and optimize manufacturing systems' performance by enhancing their macroergonomic compatibility and quality of life at work of the employees.

Thermal adaptation and phosphorus shape thermal performance in an assemblage of rainforest ants.

PubMed

Kaspari, Michael; Clay, Natalie A; Lucas, Jane; Revzen, Shai; Kay, Adam; Yanoviak, Stephen P

2016-04-01

We studied the Thermal Performance Curves (TPCs) of 87 species of rainforest ants and found support for both the Thermal Adaptation and Phosphorus-Tolerance hypotheses. TPCs relate a fitness proxy (here, worker speed) to environmental temperature. Thermal Adaptation posits that thermal generalists (ants with flatter, broader TPCs) are favored in the hotter, more variable tropical canopy compared to the cooler, less variable litter below. As predicted, species nesting in the forest canopy 1) had running speeds less sensitive to temperature; 2) ran over a greater range of temperatures; and 3) ran at lower maximum speeds. Tradeoffs between tolerance and maximum performance are often invoked for constraining the evolution of thermal generalists. There was no evidence that ant species traded off thermal tolerance for maximum speed, however. Phosphorus-Tolerance is a second mechanism for generating ectotherms able to tolerate thermal extremes. It posits that ants active at high temperatures invest in P-rich machinery to buffer their metabolism against thermal extremes. Phosphorus content in ant tissue varied three-fold, and as predicted, temperature sensitivity was lower and thermal range was higher in P-rich species. Combined, we show how the vertical distribution of hot and variable vs. cooler and stable microclimates in a single forest contribute to a diversity of TPCs and suggest that a widely varying P stoichiometry among these ants may drive some of these differences.

Deciphering the adjustment between environment and life history in annuals: lessons from a geographically-explicit approach in Arabidopsis thaliana.

PubMed

Manzano-Piedras, Esperanza; Marcer, Arnald; Alonso-Blanco, Carlos; Picó, F Xavier

2014-01-01

The role that different life-history traits may have in the process of adaptation caused by divergent selection can be assessed by using extensive collections of geographically-explicit populations. This is because adaptive phenotypic variation shifts gradually across space as a result of the geographic patterns of variation in environmental selective pressures. Hence, large-scale experiments are needed to identify relevant adaptive life-history traits as well as their relationships with putative selective agents. We conducted a field experiment with 279 geo-referenced accessions of the annual plant Arabidopsis thaliana collected across a native region of its distribution range, the Iberian Peninsula. We quantified variation in life-history traits throughout the entire life cycle. We built a geographic information system to generate an environmental data set encompassing climate, vegetation and soil data. We analysed the spatial autocorrelation patterns of environmental variables and life-history traits, as well as the relationship between environmental and phenotypic data. Almost all environmental variables were significantly spatially autocorrelated. By contrast, only two life-history traits, seed weight and flowering time, exhibited significant spatial autocorrelation. Flowering time, and to a lower extent seed weight, were the life-history traits with the highest significant correlation coefficients with environmental factors, in particular with annual mean temperature. In general, individual fitness was higher for accessions with more vigorous seed germination, higher recruitment and later flowering times. Variation in flowering time mediated by temperature appears to be the main life-history trait by which A. thaliana adjusts its life history to the varying Iberian environmental conditions. The use of extensive geographically-explicit data sets obtained from field experiments represents a powerful approach to unravel adaptive patterns of variation. In a context of current global warming, geographically-explicit approaches, evaluating the match between organisms and the environments where they live, may contribute to better assess and predict the consequences of global warming.

Tree- Rings Link Climate and Carbon Storage in a Northern Mixed Hardwood Forest

NASA Astrophysics Data System (ADS)

Chiriboga, A.

2007-12-01

The terrestrial biosphere is a variable sink for atmospheric carbon dioxide. It is important to understand how carbon storage in trees is affected by natural climate variability to better characterize the sink. Quantifying the sensitivity of forest carbon storage to climate will improve carbon budgets and have implications for forest management practices. Here we explore how climate variability affects the ability of a northern mixed hardwood forest in Michigan to sequester atmospheric carbon dioxide in woody tissues. This site is ideal for studies of carbon sequestration; The University of Michigan Biological Station is an Ameriflux site, and has detailed meteorological and biometric records, as well as CO2 flux data. We have produced an 82- year aspen (Populus grandidentata) tree-ring chronology for this site, and measured ring widths at several heights up the bole. These measurements were used to estimate annual wood volume, which represents carbon allocated to aboveground carbon stores. Standard dendroclimatological techniques are used to identify environmental factors (e.g. temperature or precipitation) that drive tree-ring increment variability in the past century, and therefore annual carbon storage in this forest. Preliminary results show that marker years within the tree- ring chronology correspond with years that have cold spring temperatures. This suggests that trees at this site are temperature sensitive.

Linking genetic and environmental factors in amphibian disease risk

PubMed Central

Savage, Anna E; Becker, Carlos G; Zamudio, Kelly R

2015-01-01

A central question in evolutionary biology is how interactions between organisms and the environment shape genetic differentiation. The pathogen Batrachochytrium dendrobatidis (Bd) has caused variable population declines in the lowland leopard frog (Lithobates yavapaiensis); thus, disease has potentially shaped, or been shaped by, host genetic diversity. Environmental factors can also influence both amphibian immunity and Bd virulence, confounding our ability to assess the genetic effects on disease dynamics. Here, we used genetics, pathogen dynamics, and environmental data to characterize L. yavapaiensis populations, estimate migration, and determine relative contributions of genetic and environmental factors in predicting Bd dynamics. We found that the two uninfected populations belonged to a single genetic deme, whereas each infected population was genetically unique. We detected an outlier locus that deviated from neutral expectations and was significantly correlated with mortality within populations. Across populations, only environmental variables predicted infection intensity, whereas environment and genetics predicted infection prevalence, and genetic diversity alone predicted mortality. At one locality with geothermally elevated water temperatures, migration estimates revealed source–sink dynamics that have likely prevented local adaptation. We conclude that integrating genetic and environmental variation among populations provides a better understanding of Bd spatial epidemiology, generating more effective conservation management strategies for mitigating amphibian declines. PMID:26136822

Investigating effect of environmental controls on dynamics of CO2 budget in a subtropical estuarial marsh wetland ecosystem

NASA Astrophysics Data System (ADS)

Lee, Sung-Ching; Fan, Chao-Jung; Wu, Zih-Yi; Juang, Jehn-Yih

2015-02-01

In this study, we quantified the ecosystem-scale CO2 exchange of two different but typical low-latitude vegetation types, para grass and reed, in a subtropical wetland ecosystem by integrating flux observation with the parameterization of environmental variables. In addition, we explored how seasonal dynamics of environmental factors affected variations in CO2 budget. The results suggest that gross primary production (GPP, in the order of 1700 gC m-2 yr-1) of CO2 was higher in this site than in previous studies of northern peatlands and estuarial wetlands because of the direct effect of environmental factors. Temperature and radiation had a larger effect than water status (soil moisture content and vapor pressure deficit) on GPP for the two low-latitude ecosystems, which differ from the results for high-latitude regions. Environmental variables had a strong but different impact on the CO2 budget for para grass and reed areas. This diversity led to different potential shifts and trends of biomass accumulation and distribution of these two typical low-latitude vegetation types under different scenarios of environmental change. The findings from this study can sufficiently provide quantitative understanding of CO2 budgets in low-latitude wetlands.

Characterizing Air Temperature Changes in the Tarim Basin over 1960–2012

PubMed Central

Peng, Dongmei; Wang, Xiujun; Zhao, Chenyi; Wu, Xingren; Jiang, Fengqing; Chen, Pengxiang

2014-01-01

There has been evidence of warming rate varying largely over space and between seasons. However, little has been done to evaluate the spatial and temporal variability of air temperature in the Tarim Basin, northwest China. In this study, we collected daily air temperature from 19 meteorological stations for the period of 1960–2012, and analyzed annual mean temperature (AMT), the annual minimum (Tmin) and maximum temperature (Tmax), and mean temperatures of all twelve months and four seasons and their anomalies. Trend analyses, standard deviation of the detrended anomaly (SDDA) and correlations were carried out to characterize the spatial and temporal variability of various mean air temperatures. Our data showed that increasing trend was much greater in the Tmin (0.55°C/10a) than in the AMT (0.25°C/10a) and Tmax (0.12°C/10a), and the fluctuation followed the same order. There were large spatial variations in the increasing trends of both AMT (from −0.09 to 0.43 °C/10a) and Tmin (from 0.15 to 1.12°C/10a). Correlation analyses indicated that AMT had a significantly linear relationship with Tmin and the mean temperatures of four seasons. There were also pronounced changes in the monthly air temperature from November to March at decadal time scale. The seasonality (i.e., summer and winter difference) of air temperature was stronger during the period of 1960–1979 than over the recent three decades. Our preliminary analyses indicated that local environmental conditions (such as elevation) might be partly responsible for the spatial variability, and large scale climate phenomena might have influences on the temporal variability of air temperature in the Tarim Basin. In particular, there was a significant correlation between index of El Niño-Southern Oscillation (ENSO) and air temperature of May (P = 0.004), and between the index of Pacific Decadal Oscillation (PDO) and air temperature of July (P = 0.026) over the interannual to decadal time scales. PMID:25375648

Vertical distributions and diel migrations of Euthecosomata in the northwest Sargasso Sea

NASA Astrophysics Data System (ADS)

Wormuth, John H.

1981-12-01

Vertical distributions and seasonal variations in abundance of nine abundant or frequent pteropod species or subspecies in the northwest Sargasso Sea are described. Factor analyses yielded two groups, diel migrators and non-migrators. In terms of water column abundances, tows taken in August and November are similar, as are tows in December and April. Most species show significant within-species agreement in depth distribution over the year but high variability in abundance. Regression analyses using environmental parameters as independent variables show significant correlations of species abundances with temperature.

A Hierarchical Analysis of Tree Growth and Environmental Drivers Across Eastern US Temperate Forests

NASA Astrophysics Data System (ADS)

Mantooth, J.; Dietze, M.

2014-12-01

Improving predictions of how forests in the eastern United States will respond to future global change requires a better understanding of the drivers of variability in tree growth rates. Current inventory data lack the temporal resolution to characterize interannual variability, while existing growth records lack the extent required to assess spatial scales of variability. Therefore, we established a network of forest inventory plots across ten sites across the eastern US, and measured growth in adult trees using increment cores. Sites were chosen to maximize climate space explored, while within sites, plots were spread across primary environmental gradients to explore landscape-level variability in growth. Using the annual growth record available from tree cores, we explored the responses of trees to multiple environmental covariates over multiple spatial and temporal scales. We hypothesized that within and across sites growth rates vary among species, and that intraspecific growth rates increase with temperature along a species' range. We also hypothesized that trees show synchrony in growth responses to landscape-scale climatic changes. Initial analyses of growth increments indicate that across sites, trees with intermediate shade tolerance, e.g. Red Oak (Quercus rubra), tend to have the highest growth rates. At the site level, there is evidence for synchrony in response to large-scale climatic events (e.g. prolonged drought and above average temperatures). However, growth responses to climate at the landscape scale have yet to be detected. Our current analysis utilizes hierarchical Bayesian state-space modeling to focus on growth responses of adult trees to environmental covariates at multiple spatial and temporal scales. This predictive model of tree growth currently incorporates observed effects at the individual, plot, site, and landscape scale. Current analysis using this model shows a potential slowing of growth in the past decade for two sites in the northeastern US (Harvard Forest and Bartlett Experimental Forest), however more work is required to determine the robustness of this trend. Finally, these observations are being incorporated into ecosystem models using the Brown Dog informatics tools and the Predictive Ecosystem Analyzer (PEcAn) data assimilation workflow.

Linking coral river runoff proxies with climate variability, hydrology and land-use in Madagascar catchments.

PubMed

Maina, Joseph; de Moel, Hans; Vermaat, Jan E; Bruggemann, J Henrich; Guillaume, Mireille M M; Grove, Craig A; Madin, Joshua S; Mertz-Kraus, Regina; Zinke, Jens

2012-10-01

Understanding the linkages between coastal watersheds and adjacent coral reefs is expected to lead to better coral reef conservation strategies. Our study aims to examine the main predictors of environmental proxies recorded in near shore corals and therefore how linked near shore reefs are to the catchment physical processes. To achieve these, we developed models to simulate hydrology of two watersheds in Madagascar. We examined relationships between environmental proxies derived from massive Porites spp. coral cores (spectral luminescence and barium/calcium ratios), and corresponding time-series (1950-2006) data of hydrology, climate, land use and human population growth. Results suggest regional differences in the main environmental drivers of reef sedimentation: on annual time-scales, precipitation, river flow and sediment load explained the variability in coral proxies of river discharge for the northeast region, while El Niño-Southern Oscillation (ENSO) and temperature (air and sea surface) were the best predictors in the southwest region. Copyright © 2012 Elsevier Ltd. All rights reserved.

The effect of air pollution and other environmental stressors on leaf fluctuating asymmetry and specific leaf area of Salix alba L.

PubMed

Wuytack, Tatiana; Wuyts, Karen; Van Dongen, Stefan; Baeten, Lander; Kardel, Fatemeh; Verheyen, Kris; Samson, Roeland

2011-10-01

We aimed at evaluating the effect of low-level air pollution on leaf area fluctuating asymmetry (FAA) and specific leaf area (SLA) of Salix alba L., taking into account other environmental factors. Cuttings were grown in standardized conditions in the near vicinity of air quality measuring stations in Belgium. Variability of SLA and FAA between measuring stations explained 83% and 7.26%, respectively, of the total variability. FAA was not influenced by air pollution or environmental factors such as shading, herbivory, air temperature and humidity. SLA was increased by an increase in shadow, while NO(x) and O(3) concentrations had only a marginal influence. The influence of SO(2) concentration was negligible. Although our data analysis suggests a relationship between SLA and NO(x)/O(3) concentration, the absence of a straightforward relationship between FAA and SLA and air pollution still questions the usefulness of these bio-indicators for monitoring air pollution. Copyright © 2011 Elsevier Ltd. All rights reserved.

Use of qualitative environmental and phenotypic variables in the context of allele distribution models: detecting signatures of selection in the genome of Lake Victoria cichlids.

PubMed

Joost, Stéphane; Kalbermatten, Michael; Bezault, Etienne; Seehausen, Ole

2012-01-01

When searching for loci possibly under selection in the genome, an alternative to population genetics theoretical models is to establish allele distribution models (ADM) for each locus to directly correlate allelic frequencies and environmental variables such as precipitation, temperature, or sun radiation. Such an approach implementing multiple logistic regression models in parallel was implemented within a computing program named MATSAM: . Recently, this application was improved in order to support qualitative environmental predictors as well as to permit the identification of associations between genomic variation and individual phenotypes, allowing the detection of loci involved in the genetic architecture of polymorphic characters. Here, we present the corresponding methodological developments and compare the results produced by software implementing population genetics theoretical models (DFDIST: and BAYESCAN: ) and ADM (MATSAM: ) in an empirical context to detect signatures of genomic divergence associated with speciation in Lake Victoria cichlid fishes.

Can tintinnids be used for discriminating water quality status in marine ecosystems?

PubMed

Feng, Meiping; Zhang, Wuchang; Wang, Weiding; Zhang, Guangtao; Xiao, Tian; Xu, Henglong

2015-12-30

Ciliated protozoa have many advantages in bioassessment of water quality. The ability of tintinnids for assessing water quality status was studied during a 7-yearcycle in Jiaozhou Bay of the Yellow Sea, northern China. The samples were collected monthly at four sites with a spatial gradient of environmental pollution. Environmental variables, e.g., temperature, salinity, chlorophyll a (Chl a), dissolved inorganic nitrogen, soluble reactive phosphate (SRP), and soluble active silicate (SRSi), were measured synchronously for comparison with biotic parameters. Results showed that: (1) tintinnid community structures represented significant differences among the four sampling sites; (2) spatial patterns of the tintinnid communities were significantly correlated with environmental variables, especially SRSi and nutrients; and (3) the community structural parameters and the five dominant species were significantly correlated with SRSi and nutrients. We suggested that tintinnids may be used as a potential bioindicator for discriminating water quality status in marine ecosystems. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chemochromic Detector for Sensing Gas Leakage and Process for Producing the Same

NASA Technical Reports Server (NTRS)

Williams, Martha K. (Inventor); Roberson, Luke B. (Inventor); Smith, Trent M. (Inventor); Tate, LaNetra Clayton (Inventor); Captain, Janine E. (Inventor)

2014-01-01

A chemochromic sensor for detecting a combustible gas, such as hydrogen, includes a chemochromic pigment mechanically mixed with a polymer and molded into a rigid or pliable shape. In a preferred embodiment, the chemochromic detector is within the material which is molded into a manufactured part, said part becoming the detector itself. The detector is robust and easily modifiable for a variety of applications and environmental conditions, such as atmospheres of inert gas, hydrogen gas, or mixtures of gases, or in environments that have variable temperature, including high temperatures such as above 100 C. and low temperatures such as below -196 C.

Greater Baltimore Open Air: an Internet of Things (IoT) approach to citizen science and community-driven climate, air quality, and urban heat island monitoring

NASA Astrophysics Data System (ADS)

Scott, A.; Kelley, C.; Azdoud, Y.; Ambikapathi, R.; Hobson, M.; Lehman, A.; Ghugare, P.; He, C.; Zaitchik, B. F.; Waugh, D.; McCormack, M.; Baja, K.

2017-12-01

Anthropogenic activities alter the urban surface and surface atmosphere, generating heat and pollutants that have known detrimental impacts on health. Monitoring these environmental variables in urban environments is made difficult by the spatial heterogeneity of urban environments, meaning that two nearby locations may have significantly different temperatures, humidities, or gas concentrations. Thus, urban monitoring often requires more densely placed monitors than current standards or budgets allow. Recent advances in low-cost sensors and Internet of Things (IoT) enabled hardware offer possible solutions. We present an autonomous wireless, open-source, IoT-enabled environmental monitor called a WeatherCube, developed for the Greater Baltimore Open Air project, funded in part by the EPA SmartCity Challenge. The WeatherCube is suitable for urban monitoring and capable of measuring meteorological variables (temperature and humidity) as well as air quality (ozone, nitrogen dioxide, and sulfur dioxide). The WeatherCube devices were built in collaboration with Johns Hopkins University, local government, and community members, including through an innovative job training program. Monitors are hosted by community partners and libraries throughout Baltimore city and surrounding communities. We present the first wave of data collected by the Greater Baltimore Open Air project and compare it to data collected by the Maryland Department of the Environment (MDE). Additionally, we will provide an overview of our experience engaging with the local makers, citizen scientists, and environmental groups to improve their urban environmental monitoring. By developing low-cost devices tailored for urban environmental monitoring, we present an innovative model for both conducting research and community outreach.

Contrasting habitat associations of imperilled endemic stream fishes from a global biodiversity hot spot

PubMed Central

2012-01-01

Background Knowledge of the factors that drive species distributions provides a fundamental baseline for several areas of research including biogeography, phylogeography and biodiversity conservation. Data from 148 minimally disturbed sites across a large drainage system in the Cape Floristic Region of South Africa were used to test the hypothesis that stream fishes have similar responses to environmental determinants of species distribution. Two complementary statistical approaches, boosted regression trees and hierarchical partitioning, were used to model the responses of four fish species to 11 environmental predictors, and to quantify the independent explanatory power of each predictor. Results Elevation, slope, stream size, depth and water temperature were identified by both approaches as the most important causal factors for the spatial distribution of the fishes. However, the species showed marked differences in their responses to these environmental variables. Elevation and slope were of primary importance for the laterally compressed Sandelia spp. which had an upstream boundary below 430 m above sea level. The fusiform shaped Pseudobarbus ‘Breede’ was strongly influenced by stream width and water temperature. The small anguilliform shaped Galaxias ‘nebula’ was more sensitive to stream size and depth, and also penetrated into reaches at higher elevation than Sandelia spp. and Pseudobarbus ‘Breede’. Conclusions The hypothesis that stream fishes have a common response to environmental descriptors is rejected. The contrasting habitat associations of stream fishes considered in this study could be a reflection of their morphological divergence which may allow them to exploit specific habitats that differ in their environmental stressors. Findings of this study encourage wider application of complementary methods in ecological studies, as they provide more confidence and deeper insights into the variables that should be managed to achieve desired conservation outcomes. PMID:23009367

Variation in the sensitivity of organismal body temperature to climate change over local and geographic scales.

PubMed

Gilman, Sarah E; Wethey, David S; Helmuth, Brian

2006-06-20

Global climate change is expected to have broad ecological consequences for species and communities. Attempts to forecast these consequences usually assume that changes in air or water temperature will translate into equivalent changes in a species' organismal body temperature. This simple change is unlikely because an organism's body temperature is determined by a complex series of interactions between the organism and its environment. Using a biophysical model, validated with 5 years of field observations, we examined the relationship between environmental temperature change and body temperature of the intertidal mussel Mytilus californianus over 1,600 km of its geographic distribution. We found that at all locations examined simulated changes in air or water temperature always produced less than equivalent changes in the daily maximum mussel body temperature. Moreover, the magnitude of body temperature change was highly variable, both within and among locations. A simulated 1 degrees C increase in air or water temperature raised the maximum monthly average of daily body temperature maxima by 0.07-0.92 degrees C, depending on the geographic location, vertical position, and temperature variable. We combined these sensitivities with predicted climate change for 2100 and calculated increases in monthly average maximum body temperature of 0.97-4.12 degrees C, depending on location and climate change scenario. Thus geographic variation in body temperature sensitivity can modulate species' experiences of climate change and must be considered when predicting the biological consequences of climate change.

Parametrization of environment by geochemistry of the varved clastic and bio- chemogenic lake sediments

NASA Astrophysics Data System (ADS)

Kalugin, Ivan; Darin, Andrey; Babich, Valery; Markovich, Tatiana; Meydan, Feray

2017-04-01

As it well known, recent quantitative estimations of high-resolution environmental variability are based on geochemical records in lake sediments. Naturally, annually laminated sediments (varves) are the best objects for paleoclimatic study, because they allow to investigate seasonal variability for understanding long-term environmental pattern. Also, varved sediments seem to be applied as the model for identification of element-indicators for non-laminated sediments. The XRF scanner on Synchrotron Radiation provides big geochemical dataset for next mathematic treatment, including time series construction. XRF scanning realizes rapid and non-destructive determinations more than 30 trace elements in a range of concentration from 1 up to 10000 ppm in annual layers. That makes sedimentary cores comparable with tree-rings. Geochemical and physicochemical investigation of lake sediments provides basic information to identify geochemical signals with paleoclimate. In general, sediment consists of mineral component, organics and carbonates. The proportions between these components are affected by environmental parameters, because measured element content or their combinations show correlation with meteodata on instrumental time interval. That allows applying geochemical variability to reconstruct the environmental parameters in the form of time series. The proportions between main components are controlled by temperature, atmospheric precipitation, water salinity and other external forcings. So, layered structure of lake bottom sediments and detectable elements content variability both represent a continuous record of environmental history. Element composition and it's climatic response. Bottom sediments represent conditions of physical weathering, temperate bioproductivity and aridity, which concern to mountain lakes within extra tropical zone. The numerical values of the parameters can be computed by software of physical-chemical modeling for gas+water+rock multisystems. Mineral matter responses to runoff. Mineral clastic part is correlated with x-ray density. It includes "clastic" rock-forming - Si, Al , Ti, Fe, Mg, Ca, K and trace elements such as Sr, Rb, Y, Zr, REE etc. Organic component of sediment more reflects temperature by means of productivity in the catchment and waterbody. Organophillic elements are Br, I, U and others soluble elements correlated with organic Carbon or LOI<500oC. Bio-chemogenic component is more characteristic for saline lakes, where Ca-, Mg- and Sr- carbonates precipitated in dependence of temperature, aridity and water salinity. Separate geochemical indicators are directly used for paleo- environmental evaluation. For example, elements with changing valency may be a proxy of outer conditions. Fe is strictly connected with sulfur in sulphide under anoxic conditions. And also Fe forms siderite in carbonate ion saturated, but calcium poor, water in the sedimentation system. Mn-enriched layers, crusts and nodules mark usually a long - term pauses of sedimentation in oxic systems. Mo/Mn ratio is good correlated with anoxic atmosphere. And so on. The work is supported by grants RFBR 16-05-00641, 16-05-00657, 15-55-46001.

Compensation for environmental change by complementary shifts of thermal sensitivity and thermoregulatory behaviour in an ectotherm.

PubMed

Glanville, E J; Seebacher, F

2006-12-01

Thermoregulating animals are thought to have evolved a preferred body temperature at which thermally sensitive performance is optimised. Even during thermoregulation, however, many animals experience pronounced variability in body temperature, and may regulate to different body temperatures depending on environmental conditions. Here we test the hypothesis that there is a trade-off between regulating to lower body temperatures in cooler conditions and locomotory and metabolic performance. Animals (estuarine crocodiles, Crocodylus porosus) acclimated to cold (N=8) conditions had significantly lower maximum and mean daily body temperatures after 33 days than warm-acclimated animals (N=9), despite performing characteristic thermoregulatory behaviours. Concomitant with behavioural changes, maximum sustained swimming speed (U(crit)) shifted to the respective mean body temperatures during acclimation (cold=20 degrees C, warm=29 degrees C), but there was no difference in the maxima between acclimation groups. Mitochondrial oxygen consumption changed significantly during acclimation, and maximum respiratory control ratios coincided with mean body temperatures in liver, muscle and heart tissues. There were significant changes in the activities of regulatory metabolic enzymes (lactate dehydrogenase, citrate synthase, cytochrome c oxidase) and these were tissue specific. The extraordinary shift in behaviour and locomotory and metabolic performance shows that within individuals, behaviour and physiology covary to maximise performance in different environments.

Tracking genes of ecological relevance using a genome scan in two independent regional population samples of Arabis alpina.

PubMed

Poncet, Bénédicte N; Herrmann, Doris; Gugerli, Felix; Taberlet, Pierre; Holderegger, Rolf; Gielly, Ludovic; Rioux, Delphine; Thuiller, Wilfried; Aubert, Serge; Manel, Stéphanie

2010-07-01

Understanding the genetic basis of adaptation in response to environmental variation is fundamental as adaptation plays a key role in the extension of ecological niches to marginal habitats and in ecological speciation. Based on the assumption that some genomic markers are correlated to environmental variables, we aimed to detect loci of ecological relevance in the alpine plant Arabis alpina L. sampled in two regions, the French (99 locations) and the Swiss (109 locations) Alps. We used an unusually large genome scan [825 amplified fragment length polymorphism loci (AFLPs)] and four environmental variables related to temperature, precipitation and topography. We detected linkage disequilibrium among only 3.5% of the considered AFLP loci. A population structure analysis identified no admixture in the study regions, and the French and Swiss Alps were differentiated and therefore could be considered as two independent regions. We applied generalized estimating equations (GEE) to detect ecologically relevant loci separately in the French and Swiss Alps. We identified 78 loci of ecological relevance (9%), which were mainly related to mean annual minimum temperature. Only four of these loci were common across the French and Swiss Alps. Finally, we discuss that the genomic characterization of these ecologically relevant loci, as identified in this study, opens up new perspectives for studying functional ecology in A. alpina, its relatives and other alpine plant species.

Informing tree-ring reconstructions with automated dendrometer data: the case of single-leaf pinyon (Pinus monophylla) from Great Basin National Park, Nevada, USA

NASA Astrophysics Data System (ADS)

Biondi, F.

2012-12-01

One of the most pressing issues in modern tree-ring science is to reduce uncertainty of reconstructions while emphasizing that the composition and dynamics of modern ecosystems cannot be understood from the present alone. I present here the latest results from research on the environmental factors that control radial growth of single-leaf pinyon (Pinus monophylla) in the Great Basin of North America using dendrometer data collected at half-hour intervals during two full growing season, 2010 and 2011. Automated (solar-powered) sensors at the site consisted of 8 point dendrometers installed on 7 trees to measure stem size, together with environmental probes that recorded air temperature, soil temperature and soil moisture. Additional meteorological variables at hourly timesteps were available from the EPA-CASTNET station located within 100 m of the dendrometer site. Daily cycles of stem expansion and contraction were quantified using the approach of Deslauriers et al. 2011, and the amount of daily radial stem increment was regressed against environmental variables. Graphical and numerical results showed that tree growth is relatively insensitive to surface soil moisture during the growing season. This finding corroborates empirical dendroclimatic results that showed how tree-ring chronologies of single-leaf pinyon are mostly a proxy for the balance between winter-spring precipitation supply and growing season evapotranspiration demand, thereby making it an ideal species for drought reconstructions.

Organismal climatology: analyzing environmental variability at scales relevant to physiological stress.

PubMed

Helmuth, Brian; Broitman, Bernardo R; Yamane, Lauren; Gilman, Sarah E; Mach, Katharine; Mislan, K A S; Denny, Mark W

2010-03-15

Predicting when, where and with what magnitude climate change is likely to affect the fitness, abundance and distribution of organisms and the functioning of ecosystems has emerged as a high priority for scientists and resource managers. However, even in cases where we have detailed knowledge of current species' range boundaries, we often do not understand what, if any, aspects of weather and climate act to set these limits. This shortcoming significantly curtails our capacity to predict potential future range shifts in response to climate change, especially since the factors that set range boundaries under those novel conditions may be different from those that set limits today. We quantitatively examine a nine-year time series of temperature records relevant to the body temperatures of intertidal mussels as measured using biomimetic sensors. Specifically, we explore how a 'climatology' of body temperatures, as opposed to long-term records of habitat-level parameters such as air and water temperatures, can be used to extrapolate meaningful spatial and temporal patterns of physiological stress. Using different metrics that correspond to various aspects of physiological stress (seasonal means, cumulative temperature and the return time of extremes) we show that these potential environmental stressors do not always occur in synchrony with one another. Our analysis also shows that patterns of animal temperature are not well correlated with simple, commonly used metrics such as air temperature. Detailed physiological studies can provide guidance to predicting the effects of global climate change on natural ecosystems but only if we concomitantly record, archive and model environmental signals at appropriate scales.

Calibration Assessment of Uncooled Thermal Cameras for Deployment on UAV platforms

NASA Astrophysics Data System (ADS)

Aragon, B.; Parkes, S. D.; Lucieer, A.; Turner, D.; McCabe, M.

2017-12-01

In recent years an array of miniaturized sensors have been developed and deployed on Unmanned Aerial Vehicles (UAVs). Prior to gaining useful data from these integrations, it is vitally important to quantify sensor accuracy, precision and cross-sensitivity of retrieved measurements on environmental variables. Small uncooled thermal frame cameras provide a novel solution to monitoring surface temperatures from UAVs with very high spatial resolution, with retrievals being used to investigate heat stress or evapotranspiration. For these studies, accuracies of a few degrees are generally required. Although radiometrically calibrated thermal cameras have recently become commercially available, confirmation of the accuracy of these sensors is required. Here we detail a system for investigating the accuracy and precision, start up stabilisation time, dependence of retrieved temperatures on ambient temperatures and image vignetting. The calibration system uses a relatively inexpensive blackbody source deployed with the sensor inside an environmental chamber to maintain and control the ambient temperature. Calibration of a number of different thermal sensors commonly used for UAV deployment was investigated. Vignetting was shown to be a major limitation on sensor accuracy, requiring characterization through measuring a spatially uniform temperature target such as the blackbody. Our results also showed that a stabilization period is required after powering on the sensors and before conducting an aerial survey. Through use of the environmental chamber it was shown the ambient temperature influenced the temperatures retrieved by the different sensors. This study illustrates the importance of determining the calibration and cross-sensitivities of thermal sensors to obtain accurate thermal maps that can be used to study crop ecosystems.

Statistical downscaling of mean temperature, maximum temperature, and minimum temperature on the Loess Plateau, China

NASA Astrophysics Data System (ADS)

Jiang, L.

2017-12-01

Climate change is considered to be one of the greatest environmental threats. Global climate models (GCMs) are the primary tool used for studying climate change. However, GCMs are limited because of their coarse spatial resolution and inability to resolve important sub-grid scale features such as terrain and clouds. Statistical downscaling methods can be used to downscale large-scale variables to local-scale. In this study, we assess the applicability of the Statistical Downscaling Model (SDSM) in downscaling the outputs from Beijing Normal University Earth System Model (BNU-ESM). The study focus on the the Loess Plateau, China, and the variables for downscaling include daily mean temperature (TMEAN), maximum temperature (TMAX) and minimum temperature (TMIN). The results show that SDSM performs well for these three climatic variables on the Loess Plateau. After downscaling, the root mean square errors for TMEAN, TMAX, TMIN for BNU-ESM were reduced by 70.9%, 75.1%, and 67.2%, respectively. All the rates of change in TMEAN, TMAX and TMIN during the 21st century decreased after SDSM downscaling. We also show that SDSM can effectively reduce uncertainty, compared with the raw model outputs. TMEAN uncertainty was reduced by 27.1%, 26.8%, and 16.3% for the future scenarios of RCP 2.6, RCP 4.5 and RCP 8.5, respectively. The corresponding reductions in uncertainty were 23.6%, 30.7%, and 18.7% for TMAX; 37.6%, 31.8%, and 23.2% for TMIN.

Sex-specific differences of craniofacial traits in Croatia: the impact of environment in a small geographic area.

PubMed

Buretic-Tomljanovic, Alena; Giacometti, Jasminka; Ostojic, Sasa; Kapovic, Miljenko

2007-01-01

Craniometric variation in humans reflects different genetic and environmental influences. Long-term climatic adaptation is less likely to show an impact on size and shape variation in a small local area than at the global level. The aim of this work was to assess the contribution of the particular environmental factors to body height and craniofacial variability in a small geographic area of Croatia. A total of 632 subjects, aged 18-21, participated in the survey. Body height, head length, head breadth, head height, head circumference, cephalic index, morphological face height, face breadth, and facial index were analysed regarding geographic, climatic and dietary conditions in different regions of the country, and correlated with the specific climatic variables (cumulative multiyear sunshine duration, cumulative multiyear average precipitation, multiyear average air temperatures) and calcium concentrations in drinking water. Significant differences between groups classified according to geographic, climatic or dietary affiliation, and the impact of the environmental predictors on the variation in the investigated traits were assessed using multiple forward stepwise regression analyses. Higher body height measures in both sexes were significantly correlated with Mediterranean diet type. Mediterranean diet type also contributed to higher head length and head circumference measures in females. Cephalic index values correlated to geographic regions in both sexes, showing an increase from southern to eastern Croatia. In the same direction, head length significantly decreased in males and head breadth increased in females. Mediterranean climate was associated with higher and narrower faces in females. The analysis of the particular climatic variables did not reveal a significant influence on body height in either sex. Concurrently, climatic features influenced all craniofacial traits in females and only head length and facial index in males. Mediterranean climate, characterized by higher average sunshine duration, higher average precipitation and higher average air temperatures, was associated with longer, higher and narrower skulls, higher head circumference, lower cephalic index, and higher and narrower faces (lower facial index). Calcium concentrations in drinking water did not correlate significantly with any dependent variable. A significant effect of environmental factors on body height and craniofacial variability was found in Croatian young adult population. This effect was more pronounced in females, revealing sex-specific craniofacial differentiation. However, the impact of environment was low and may explain only 1.0-7.32% variation of the investigated traits.

Use of Wearable Sensors and Biometric Variables in an Artificial Pancreas System.

PubMed

Turksoy, Kamuran; Monforti, Colleen; Park, Minsun; Griffith, Garett; Quinn, Laurie; Cinar, Ali

2017-03-07

An artificial pancreas (AP) computes the optimal insulin dose to be infused through an insulin pump in people with Type 1 Diabetes (T1D) based on information received from a continuous glucose monitoring (CGM) sensor. It has been recognized that exercise is a major challenge in the development of an AP system. The use of biometric physiological variables in an AP system may be beneficial for prevention of exercise-induced challenges and better glucose regulation. The goal of the present study is to find a correlation between biometric variables such as heart rate (HR), heat flux (HF), skin temperature (ST), near-body temperature (NBT), galvanic skin response (GSR), and energy expenditure (EE), 2D acceleration-mean of absolute difference (MAD) and changes in glucose concentrations during exercise via partial least squares (PLS) regression and variable importance in projection (VIP) in order to determine which variables would be most useful to include in a future artificial pancreas. PLS and VIP analyses were performed on data sets that included seven different types of exercises. Data were collected from 26 clinical experiments. Clinical results indicate ST to be the most consistently important (important for six out of seven tested exercises) variable over all different exercises tested. EE and HR are also found to be important variables over several types of exercise. We also found that the importance of GSR and NBT observed in our experiments might be related to stress and the effect of changes in environmental temperature on glucose concentrations. The use of the biometric measurements in an AP system may provide better control of glucose concentration.

Long-term variability and environmental preferences of calycophoran siphonophores in the Bay of Villefranche (north-western Mediterranean)

NASA Astrophysics Data System (ADS)

Licandro, P.; Souissi, S.; Ibanez, F.; Carré, C.

2012-05-01

Long-term variability of the main calycophoran siphonophores was investigated between 1974 and 1999 in a coastal station in the north-western Mediterranean. The data were collected at weekly frequency using a macroplankton net (680 μm mesh size) adapted to quantitatively sample delicate gelatinous plankton. A 3-year collection (1967-1969) of siphonophores from offshore waters using the same methodology showed that the patterns of variability observed inshore were representative of siphonophores’ changes at a regional scale. The aims of the study were: (i) to investigate the patterns of variability that characterised the dominant calycophoran species and assemblages; (ii) to identify the environmental optima that were associated with a significant increase in the dominant siphonophore species and (iii) to verify the influence of hydroclimatic variability on long-term changes of siphonophores. Our results showed that during nearly 3 decades the standing stock of calycophoran siphonophores did not show any significant change, with the annual maximum usually recorded in spring as a result of high densities of the dominant species Lensia subtilis, Muggiaea kochi and Muggiaea atlantica. Nevertheless, major changes in community composition occurred within the calycophoran population. Since the middle 1980s, M. kochi, once the most dominant species, started to decrease allowing other species, the congeneric M. atlantica and Chelophyes appendiculata, to increasingly dominate in spring and summer-autumn, respectively. The comparison of environmental and biotic long-term trends suggests that the decrease of M. kochi was triggered by hydrological changes that occurred in the north-western Mediterranean under the forcing of large-scale climate oscillations. Salinity, water stratification and water temperature were the main hydroclimatic factors associated with a significant increase of siphonophores, different species showing different environmental preferences.

Higher-order statistical moments and a procedure that detects potentially anomalous years as two alternative methods describing alterations in continuous environmental data

USGS Publications Warehouse

Arismendi, Ivan; Johnson, Sherri L.; Dunham, Jason B.

2015-01-01

Statistics of central tendency and dispersion may not capture relevant or desired characteristics of the distribution of continuous phenomena and, thus, they may not adequately describe temporal patterns of change. Here, we present two methodological approaches that can help to identify temporal changes in environmental regimes. First, we use higher-order statistical moments (skewness and kurtosis) to examine potential changes of empirical distributions at decadal extents. Second, we adapt a statistical procedure combining a non-metric multidimensional scaling technique and higher density region plots to detect potentially anomalous years. We illustrate the use of these approaches by examining long-term stream temperature data from minimally and highly human-influenced streams. In particular, we contrast predictions about thermal regime responses to changing climates and human-related water uses. Using these methods, we effectively diagnose years with unusual thermal variability and patterns in variability through time, as well as spatial variability linked to regional and local factors that influence stream temperature. Our findings highlight the complexity of responses of thermal regimes of streams and reveal their differential vulnerability to climate warming and human-related water uses. The two approaches presented here can be applied with a variety of other continuous phenomena to address historical changes, extreme events, and their associated ecological responses.

Global Gradients of Coral Exposure to Environmental Stresses and Implications for Local Management

PubMed Central

Maina, Joseph; McClanahan, Tim R.; Venus, Valentijn; Ateweberhan, Mebrahtu; Madin, Joshua

2011-01-01

Background The decline of coral reefs globally underscores the need for a spatial assessment of their exposure to multiple environmental stressors to estimate vulnerability and evaluate potential counter-measures. Methodology/Principal Findings This study combined global spatial gradients of coral exposure to radiation stress factors (temperature, UV light and doldrums), stress-reinforcing factors (sedimentation and eutrophication), and stress-reducing factors (temperature variability and tidal amplitude) to produce a global map of coral exposure and identify areas where exposure depends on factors that can be locally managed. A systems analytical approach was used to define interactions between radiation stress variables, stress reinforcing variables and stress reducing variables. Fuzzy logic and spatial ordinations were employed to quantify coral exposure to these stressors. Globally, corals are exposed to radiation and reinforcing stress, albeit with high spatial variability within regions. Based on ordination of exposure grades, regions group into two clusters. The first cluster was composed of severely exposed regions with high radiation and low reducing stress scores (South East Asia, Micronesia, Eastern Pacific and the central Indian Ocean) or alternatively high reinforcing stress scores (the Middle East and the Western Australia). The second cluster was composed of moderately to highly exposed regions with moderate to high scores in both radiation and reducing factors (Caribbean, Great Barrier Reef (GBR), Central Pacific, Polynesia and the western Indian Ocean) where the GBR was strongly associated with reinforcing stress. Conclusions/Significance Despite radiation stress being the most dominant stressor, the exposure of coral reefs could be reduced by locally managing chronic human impacts that act to reinforce radiation stress. Future research and management efforts should focus on incorporating the factors that mitigate the effect of coral stressors until long-term carbon reductions are achieved through global negotiations. PMID:21860667

Modeling seasonal variability of fecal coliform in natural surface waters using the modified SWAT

NASA Astrophysics Data System (ADS)

Cho, Kyung Hwa; Pachepsky, Yakov A.; Kim, Minjeong; Pyo, JongCheol; Park, Mi-Hyun; Kim, Young Mo; Kim, Jung-Woo; Kim, Joon Ha

2016-04-01

Fecal coliforms are indicators of pathogens and thereby, understanding of their fate and transport in surface waters is important to protect drinking water sources and public health. We compiled fecal coliform observations from four different sites in the USA and Korea and found a seasonal variability with a significant connection to temperature levels. In all observations, fecal coliform concentrations were relatively higher in summer and lower during the winter season. This could be explained by the seasonal dominance of growth or die-off of bacteria in soil and in-stream. Existing hydrologic models, however, have limitations in simulating the seasonal variability of fecal coliform. Soil and in-stream bacterial modules of the Soil and Water Assessment Tool (SWAT) model are oversimplified in that they exclude simulations of alternating bacterial growth. This study develops a new bacteria subroutine for the SWAT in an attempt to improve its prediction accuracy. We introduced critical temperatures as a parameter to simulate the onset of bacterial growth/die-off and to reproduce the seasonal variability of bacteria. The module developed in this study will improve modeling for environmental management schemes.

Optical and structural studies of films grown thermally on zirconium surfaces

NASA Astrophysics Data System (ADS)

Morgan, J. M.; McNatt, J. S.; Shepard, M. J.; Farkas, N.; Ramsier, R. D.

2002-06-01

Variable angle IR reflection spectroscopy and atomic force microscopy are used to determine the thickness and morphology of films grown thermally on Zr surfaces in air. The density and homogeneity of these films increases with temperature in the range studied (773-873 K) and growth at the highest temperature follows cubic rate law kinetics. We demonstrate a structure-property relationship for these thermally grown films and suggest the application of IR reflectivity as an inspection method during the growth of environmentally passive films on industrial Zr components.

Coral calcification and reef development under natural disturbances

NASA Astrophysics Data System (ADS)

Wall, M.; Schmidt, G. M.; Khokkiatiwong, S.; Richter, C.

2012-04-01

Corals are impressive ecosystem engineers shaping and influencing tropical shallow water environments through their complex carbonate framework. Calcification a key physiological process determining coral growth and reef development, is highly dependent on constant environmental conditions, especially temperature, aragonite saturation and pH. However, not in all reef areas such constant and stable conditons can be found. Coral reefs located in the Andaman Sea off the western Thai coast are subjected to large amplitude internal waves (LAIW), which induce strong oscillations in several physical and chemical environmental parameters and hence, offer the possibility to study the influence of fluctuating conditions on coral reefs. Characteristics of these oscillations as well as reef framework development have been studied on reefs of five islands, which are exposed to LAIW along their western sides and LAIW-sheltered on their eastern sides. LAIW reach these shallow water reef areas all year round, however, strongest fluctuations were recorded during the dry season (November to May) with temperature drops of up to 8°C and pH values ranging from 8.22-7.90. Several (up to 12) sudden changes in environmental conditions can occur during a day, which differ in intensity and duration. Salinity, pH and oxygen are well correlated with changes in temperature and thus, temperature variability calculated as degree days cooling (DDC) was used as proxy for the complex set of environmental variability. This proxy enabled us to combine frequency and intensity of disturbances in one value and allowed for ranking each study location according to the severity of LAIW disturbances. Framework height was found to be clearly reduced in areas exposed to LAIW compared to the complex three-dimensional carbonate framework in the LAIW-sheltered reefs. Moreover, it showed a strong linear correlation with DDC (Rsqr=0.732, p=0.007) indicating the negative effect of pulsed disturbances on coral reef development. LAIW are a ubiquitous phenomenon especially in tropical oceans where coral communities exposed to these internal waves may offer a unique possibility to study in situ the effect of several cumulative stressors on coral- and reef development, as well as the consequences for the whole reef community.

Rising water temperatures, reproduction and recruitment of an invasive oyster, Crassostrea gigas, on the French Atlantic coast.

PubMed

Dutertre, Mickaël; Beninger, Peter G; Barillé, Laurent; Papin, Mathias; Haure, Joël

2010-02-01

The recent appearance and invasion of feral oysters (Crassostrea gigas) along the northern European Atlantic coast, underscores the necessity to investigate the relationship between environmental variables, reproductive physiology, larval development and recruitment. We studied these relationships at both high (HT) and intermediate (IT) - turbidity sites, through historical data on water temperatures, multi-parameter environmental probes, histological analyses, and field collections of planktonic larvae and settled post-larvae in 2005 and 2006. A progressive warming trend was observed, especially since 1995, when oyster proliferation first became severe. Threshold temperatures for oocyte growth, larval development and settlement were achieved in both 2005 and 2006. The HT site showed greater numbers of larvae and post-larvae than the IT site for both years, with the highest numbers of post-larvae observed at both sites during the warmer summer of 2006. These results suggest that increased temperatures in northern European waters allow successful reproduction, larval development, and recruitment of C. gigas. High turbidity conditions further enhance this success. 2009 Elsevier Ltd. All rights reserved.

Environmental influence on mussel (Mytilus edulis) growth - A quantile regression approach

NASA Astrophysics Data System (ADS)

Bergström, Per; Lindegarth, Mats

2016-03-01

The need for methods for sustainable management and use of coastal ecosystems has increased in the last century. A key aspect for obtaining ecologically and economically sustainable aquaculture in threatened coastal areas is the requirement of geographic information of growth and potential production capacity. Growth varies over time and space and depends on a complex pattern of interactions between the bivalve and a diverse range of environmental factors (e.g. temperature, salinity, food availability). Understanding these processes and modelling the environmental control of bivalve growth has been central in aquaculture. In contrast to the most conventional modelling techniques, quantile regression can handle cases where not all factors are measured and provide the possibility to estimate the effect at different levels of the response distribution and give therefore a more complete picture of the relationship between environmental factors and biological response. Observation of the relationships between environmental factors and growth of the bivalve Mytilus edulis revealed relationships that varied both among level of growth rate and within the range of environmental variables along the Swedish west coast. The strongest patterns were found for water oxygen concentration level which had a negative effect on growth for all oxygen levels and growth levels. However, these patterns coincided with differences in growth among periods and very little of the remaining variability within periods could be explained indicating that interactive processes masked the importance of the individual variables. By using quantile regression and local regression (LOESS) this study was able to provide valuable information on environmental factors influencing the growth of M. edulis and important insight for the development of ecosystem based management tools of aquaculture activities, its use in mitigation efforts and successful management of human use of coastal areas.

Widespread local chronic stressors in Caribbean coastal habitats

PubMed Central

Collin, Rachel; Bastidas, Carolina; Cróquer, Aldo; Gayle, Peter M. H.; Jordán-Dahlgren, Eric; Koltes, Karen; Oxenford, Hazel; Rodriguez-Ramirez, Alberto; Weil, Ernesto; Alemu, Jahson; Bone, David; Buchan, Kenneth C.; Creary Ford, Marcia; Escalante-Mancera, Edgar; Garzón-Ferreira, Jaime; Guzmán, Hector M.; Kjerfve, Björn; Klein, Eduardo; McCoy, Croy; Potts, Arthur C.; Ruíz-Rentería, Francisco; Smith, Struan R.; Tschirky, John; Cortés, Jorge

2017-01-01

Coastal ecosystems and the livelihoods they support are threatened by stressors acting at global and local scales. Here we used the data produced by the Caribbean Coastal Marine Productivity program (CARICOMP), the longest, largest monitoring program in the wider Caribbean, to evidence local-scale (decreases in water quality) and global-scale (increases in temperature) stressors across the basin. Trend analyses showed that visibility decreased at 42% of the stations, indicating that local-scale chronic stressors are widespread. On the other hand, only 18% of the stations showed increases in water temperature that would be expected from global warming, partially reflecting the limits in detecting trends due to inherent natural variability of temperature data. Decreases in visibility were associated with increased human density. However, this link can be decoupled by environmental factors, with conditions that increase the flush of water, dampening the effects of human influence. Besides documenting environmental stressors throughout the basin, our results can be used to inform future monitoring programs, if the desire is to identify stations that provide early warning signals of anthropogenic impacts. All CARICOMP environmental data are now available, providing an invaluable baseline that can be used to strengthen research, conservation, and management of coastal ecosystems in the Caribbean basin. PMID:29261694

Cost of resistance to trematodes in freshwater snail populations with low clonal diversity.

PubMed

Dagan, Yael; Kosman, Evsey; Ben-Ami, Frida

2017-12-13

The persistence of high genetic variability in natural populations garners considerable interest among ecologists and evolutionary biologists. One proposed hypothesis for the maintenance of high levels of genetic diversity relies on frequency-dependent selection imposed by parasites on host populations (Red Queen hypothesis). A complementary hypothesis suggests that a trade-off between fitness costs associated with tolerance to stress factors and fitness costs associated with resistance to parasites is responsible for the maintenance of host genetic diversity. The present study investigated whether host resistance to parasites is traded off with tolerance to environmental stress factors (high/low temperatures, high salinity), by comparing populations of the freshwater snail Melanoides tuberculata with low vs. high clonal diversity. Since polyclonal populations were found to be more parasitized than populations with low clonal diversity, we expected them to be tolerant to environmental stress factors. We found that clonal diversity explained most of the variation in snail survival under high temperature, thereby suggesting that tolerance to high temperatures of clonally diverse populations is higher than that of populations with low clonal diversity. Our results suggest that resistance to parasites may come at a cost of reduced tolerance to certain environmental stress factors.

Diversity and distribution of deep-sea shrimps in the Ross Sea region of Antarctica.

PubMed

Basher, Zeenatul; Bowden, David A; Costello, Mark J

2014-01-01

Although decapod crustaceans are widespread in the oceans, only Natantia (shrimps) are common in the Antarctic. Because remoteness, depth and ice cover restrict sampling in the South Ocean, species distribution modelling is a useful tool for evaluating distributions. We used physical specimen and towed camera data to describe the diversity and distribution of shrimps in the Ross Sea region of Antarctica. Eight shrimp species were recorded: Chorismus antarcticus; Notocrangon antarcticus; Nematocarcinus lanceopes; Dendrobranchiata; Pasiphaea scotiae; Pasiphaea cf. ledoyeri; Petalidium sp., and a new species of Lebbeus. For the two most common species, N. antarcticus and N. lanceopes, we used maximum entropy modelling, based on records of 60 specimens and over 1130 observations across 23 sites in depths from 269 m to 3433 m, to predict distributions in relation to environmental variables. Two independent sets of environmental data layers at 0.05° and 0.5° resolution respectively, showed how spatial resolution affected the model. Chorismus antarcticus and N. antarcticus were found only on the continental shelf and upper slopes, while N. lanceopes, Lebbeus n. sp., Dendrobranchiata, Petalidium sp., Pasiphaea cf. ledoyeri, and Pasiphaea scotiae were found on the slopes, seamounts and abyssal plain. The environmental variables that contributed most to models for N. antarcticus were depth, chlorophyll-a concentration, temperature, and salinity, and for N. lanceopes were depth, ice concentration, seabed slope/rugosity, and temperature. The relative ranking, but not the composition of these variables changed in models using different spatial resolutions, and the predicted extent of suitable habitat was smaller in models using the finer-scale environmental layers. Our modelling indicated that shrimps were widespread throughout the Ross Sea region and were thus likely to play important functional role in the ecosystem, and that the spatial resolution of data needs to be considered both in the use of species distribution models.

Diversity and Distribution of Deep-Sea Shrimps in the Ross Sea Region of Antarctica

PubMed Central

Basher, Zeenatul; Bowden, David A.; Costello, Mark J.

2014-01-01

Although decapod crustaceans are widespread in the oceans, only Natantia (shrimps) are common in the Antarctic. Because remoteness, depth and ice cover restrict sampling in the South Ocean, species distribution modelling is a useful tool for evaluating distributions. We used physical specimen and towed camera data to describe the diversity and distribution of shrimps in the Ross Sea region of Antarctica. Eight shrimp species were recorded: Chorismus antarcticus; Notocrangon antarcticus; Nematocarcinus lanceopes; Dendrobranchiata; Pasiphaea scotiae; Pasiphaea cf. ledoyeri; Petalidium sp., and a new species of Lebbeus. For the two most common species, N. antarcticus and N. lanceopes, we used maximum entropy modelling, based on records of 60 specimens and over 1130 observations across 23 sites in depths from 269 m to 3433 m, to predict distributions in relation to environmental variables. Two independent sets of environmental data layers at 0.05° and 0.5° resolution respectively, showed how spatial resolution affected the model. Chorismus antarcticus and N. antarcticus were found only on the continental shelf and upper slopes, while N. lanceopes, Lebbeus n. sp., Dendrobranchiata, Petalidium sp., Pasiphaea cf. ledoyeri, and Pasiphaea scotiae were found on the slopes, seamounts and abyssal plain. The environmental variables that contributed most to models for N. antarcticus were depth, chlorophyll-a concentration, temperature, and salinity, and for N. lanceopes were depth, ice concentration, seabed slope/rugosity, and temperature. The relative ranking, but not the composition of these variables changed in models using different spatial resolutions, and the predicted extent of suitable habitat was smaller in models using the finer-scale environmental layers. Our modelling indicated that shrimps were widespread throughout the Ross Sea region and were thus likely to play important functional role in the ecosystem, and that the spatial resolution of data needs to be considered both in the use of species distribution models. PMID:25051333

Critical Knowledge Gaps in Our Understanding of Environmental Cycling and Transmission of Leptospira spp.

PubMed Central

Olivas, Sonora

2017-01-01

ABSTRACT Exposure to soil or water contaminated with the urine of Leptospira-infected animals is the most common way in which humans contract leptospirosis. Entire populations can be at high risk of leptospirosis while working in inundated fields, when engaging in aquatic sports, or after periods of heavy rainfall. The risk of infection after contact with these environmental sources depends on the ability of Leptospira bacteria to survive, persist, and infect new hosts. Multiple variables such as soil and water pH, temperature, and even environmental microbial communities are likely to shape the environmental conditions needed by the pathogen to persist. Here we review what is known about the environmental phase of the infectious Leptospira transmission cycle and identify knowledge gaps that will serve as a guide for future research. PMID:28754706

Development of a New ICT-Based Multisensor Blood Pressure Monitoring System for Use in Hemodynamic Biomarker-Initiated Anticipation Medicine for Cardiovascular Disease: The National IMPACT Program Project.

PubMed

Kario, Kazuomi; Tomitani, Naoko; Kanegae, Hiroshi; Yasui, Nobuhiko; Nishizawa, Masafumi; Fujiwara, Takeshi; Shigezumi, Takeya; Nagai, Ryozo; Harada, Hiroshi

We have developed a multisensor home and ambulatory blood pressure (BP) monitoring system for monitoring 24-h central and brachial BP variability concurrent with physical activity (PA), temperature, and atmospheric pressure. The new BP monitoring system utilizes our recently developed biological and environmental signal monitoring Information Communication Technology/Internet of Things system, which can simultaneously monitor the environment (temperature, illumination, etc.) of different rooms in a house (entryway, bedroom, living room, bathing room, and toilet), and a wrist-type high-sensitivity actigraph for identifying the location of patients. By collecting both data on BP and environmental parameters, the system can assess the brachial and central hemodynamic BP reactivity profiles of patients, such as actisensitivity (BP change with PA), thermosensitivity (with temperature), and atmospheric sensitivity (with atmospheric pressure). We used this new system to monitor ambulatory BP variability in outpatients with one or more cardiovascular disease (CVD) risk factors both in summer and winter. Actisensitivity (the slope of the regression line of ambulatory BP against the log-physical activity) was higher in winter than summer. By multi-level analysis using the parameters monitored by this system, we estimated the ambulatory BPs under different conditions. The individual time-series big data collected by this system will contribute to anticipation medicine for CVD. Copyright © 2017 Elsevier Inc. All rights reserved.

Modeling Effects of Temperature, Soil, Moisture, Nutrition and Variety As Determinants of Severity of Pythium Damping-Off and Root Disease in Subterranean Clover

PubMed Central

You, Ming P.; Rensing, Kelly; Renton, Michael; Barbetti, Martin J.

2017-01-01

Subterranean clover (Trifolium subterraneum) is a critical pasture legume in Mediterranean regions of southern Australia and elsewhere, including Mediterranean-type climatic regions in Africa, Asia, Australia, Europe, North America, and South America. Pythium damping-off and root disease caused by Pythium irregulare is a significant threat to subterranean clover in Australia and a study was conducted to define how environmental factors (viz. temperature, soil type, moisture and nutrition) as well as variety, influence the extent of damping-off and root disease as well as subterranean clover productivity under challenge by this pathogen. Relationships were statistically modeled using linear and generalized linear models and boosted regression trees. Modeling found complex relationships between explanatory variables and the extent of Pythium damping-off and root rot. Linear modeling identified high-level (4 or 5-way) significant interactions for each dependent variable (dry shoot and root weight, emergence, tap and lateral root disease index). Furthermore, all explanatory variables (temperature, soil, moisture, nutrition, variety) were found significant as part of some interaction within these models. A significant five-way interaction between all explanatory variables was found for both dry shoot and root dry weights, and a four way interaction between temperature, soil, moisture, and nutrition was found for both tap and lateral root disease index. A second approach to modeling using boosted regression trees provided support for and helped clarify the complex nature of the relationships found in linear models. All explanatory variables showed at least 5% relative influence on each of the five dependent variables. All models indicated differences due to soil type, with the sand-based soil having either higher weights, greater emergence, or lower disease indices; while lowest weights and less emergence, as well as higher disease indices, were found for loam soil and low temperature. There was more severe tap and lateral root rot disease in higher moisture situations. PMID:29184544

Automated multivariate analysis of multi-sensor data submitted online: Real-time environmental monitoring.

PubMed

Eide, Ingvar; Westad, Frank

2018-01-01

A pilot study demonstrating real-time environmental monitoring with automated multivariate analysis of multi-sensor data submitted online has been performed at the cabled LoVe Ocean Observatory located at 258 m depth 20 km off the coast of Lofoten-Vesterålen, Norway. The major purpose was efficient monitoring of many variables simultaneously and early detection of changes and time-trends in the overall response pattern before changes were evident in individual variables. The pilot study was performed with 12 sensors from May 16 to August 31, 2015. The sensors provided data for chlorophyll, turbidity, conductivity, temperature (three sensors), salinity (calculated from temperature and conductivity), biomass at three different depth intervals (5-50, 50-120, 120-250 m), and current speed measured in two directions (east and north) using two sensors covering different depths with overlap. A total of 88 variables were monitored, 78 from the two current speed sensors. The time-resolution varied, thus the data had to be aligned to a common time resolution. After alignment, the data were interpreted using principal component analysis (PCA). Initially, a calibration model was established using data from May 16 to July 31. The data on current speed from two sensors were subject to two separate PCA models and the score vectors from these two models were combined with the other 10 variables in a multi-block PCA model. The observations from August were projected on the calibration model consecutively one at a time and the result was visualized in a score plot. Automated PCA of multi-sensor data submitted online is illustrated with an attached time-lapse video covering the relative short time period used in the pilot study. Methods for statistical validation, and warning and alarm limits are described. Redundant sensors enable sensor diagnostics and quality assurance. In a future perspective, the concept may be used in integrated environmental monitoring.

Evaluating Spatial Heterogeneity and Environmental Variability Inferred from Branched Glycerol Dialkyl Glycerol Tetraethers (GDGTs) Distribution in Soils from Valles Caldera, New Mexic

NASA Astrophysics Data System (ADS)

Contreras Quintana, S. H.; Werne, J. P.; Brown, E. T.; Halbur, J.; Sinninghe Damsté, , J.; Schouten, S.; Correa-Metrio, A.; Fawcett, P. J.

2014-12-01

Branched glycerol dialkyl glycerol tetraethers (GDGTs) are recently discovered bacterial membrane lipids, ubiquitously present in peat bogs and soils, as well as in rivers, lakes and lake sediments. Their distribution appears to be controlled mainly by soil pH and annual mean air temperature (MAT) and they have been increasingly used as paleoclimate proxies in sedimentary records. In order to validate their application as paleoclimate proxies, it is essential evaluate the influence of small scale environmental variability on their distribution. Initial application of the original soil-based branched GDGT distribution proxy to lacustrine sediments from Valles Caldera, New Mexico (NM) was promising, producing a viable temperature record spanning two glacial/interglacial cycles. In this study, we assess the influence of analytical and spatial soil heterogeneity on the concentration and distribution of 9 branched GDGTs in soils from Valles Caldera, and show how this variability is propagated to MAT and pH estimates using multiple soil-based branched GDGT transfer functions. Our results show that significant differences in the abundance and distribution of branched GDGTs in soil can be observed even within a small area such as Valles Caldera. Although the original MBT-CBT calibration appears to give robust MAT estimates and the newest calibration provides pH estimates in better agreement with modern local soils in Valles Caldera, the environmental heterogeneity (e.g. vegetation type and soil moisture) appears to affect the precision of MAT and pH estimates. Furthermore, the heterogeneity of soils leads to significant variability among samples taken even from within a square meter. While such soil heterogeneity is not unknown (and is typically controlled for by combining multiple samples), this study quantifies heterogeneity relative to branched GDGT-based proxies for the first time, indicating that care must be taken with samples from heterogeneous soils in MAT and pH reconstructions.

Influences of body size and environmental factors on autumn downstream migration of bull trout in the Boise River, Idaho

USGS Publications Warehouse

Monnot, L.; Dunham, J.B.; Hoem, T.; Koetsier, P.

2008-01-01

Many fishes migrate extensively through stream networks, yet patterns are commonly described only in terms of the origin and destination of migration (e.g., between natal and feeding habitats). To better understand patterns of migration in bull trout,Salvelinus confluentus we studied the influences of body size (total length [TL]) and environmental factors (stream temperature and discharge) on migrations in the Boise River basin, Idaho. During the autumns of 2001-2003, we tracked the downstream migrations of 174 radio-tagged bull trout ranging in size from 21 to 73 cm TL. The results indicated that large bull trout (>30 cm) were more likely than small fish to migrate rapidly downstream after spawning in headwater streams in early autumn. Large bull trout also had a higher probability of arriving at the current terminus of migration in the system, Arrowrock Reservoir. The rate of migration by small bull trout was more variable and individuals were less likely to move into Arrowrock Reservoir. The rate of downstream migration by all fish was slower when stream discharge was greater. Temperature was not associated with the rate of migration. These findings indicate that fish size and environmentally related changes in behavior have important influences on patterns of migration. In a broader context, these results and other recent work suggest, at least in some cases, that commonly used classifications of migratory behavior may not accurately reflect the full range of behaviors and variability among individuals (or life stages) and environmental conditions. ?? Copyright by the American Fisheries Society 2008.

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

PubMed Central

Mantzouki, Evanthia; Fastner, Jutta; de Senerpont Domis, Lisette; Wilk-Woźniak, Elżbieta; Koreivienė, Judita; Verstijnen, Yvon; Krztoń, Wojciech; Walusiak, Edward; Karosienė, Jūratė; Kasperovičienė, Jūratė; Savadova, Ksenija; Vitonytė, Irma; Budzyńska, Agnieszka; Szeląg-Wasielewska, Elżbieta; Domek, Piotr; Messyasz, Beata; Pełechata, Aleksandra; Pełechaty, Mariusz; Kokocinski, Mikolaj; García-Murcia, Ana; Real, Monserrat; Romans, Elvira; Noguero-Ribes, Jordi; Duque, David Parreño; Karakaya, Nusret; Häggqvist, Kerstin; Beklioğlu, Meryem; Filiz, Nur; Iskin, Uğur; Bezirci, Gizem; Tavşanoğlu, Ülkü Nihan; Panou, Manthos; Fakioglu, Özden; Avagianos, Christos; Çelik, Kemal; Yilmaz, Mete; Marcé, Rafael; Buck, Moritz; Colom-Montero, William; Mustonen, Kristiina; Pierson, Don; Yang, Yang; Raposeiro, Pedro M.; Antoniou, Maria G.; Tsiarta, Nikoletta; McCarthy, Valerie; Perello, Victor C.; Feldmann, Tõnu; Panksep, Kristel; Tuvikene, Lea; Gagala, Ilona; Çınar, Şakir; Çapkın, Kadir; Yağcı, Abdulkadir; Cesur, Mehmet; Bilgin, Fuat; Bulut, Cafer; Uysal, Rahmi; Boscaini, Adriano; Cerasino, Leonardo; Richardson, Jessica; Visser, Petra M.; Verspagen, Jolanda M. H.; Karan, Tünay; Ochocka, Agnieszka; Pasztaleniec, Agnieszka; Köker, Latife; Albay, Meriç; Maronić, Dubravka Špoljarić; Stević, Filip; Pfeiffer, Tanja Žuna; Fonvielle, Jeremy; Rothhaupt, Karl-Otto; Hansson, Lars-Anders; Bláha, Luděk; Geriš, Rodan; Fránková, Markéta; Koçer, Mehmet Ali Turan; Alp, Mehmet Tahir; Remec-Rekar, Spela; Elersek, Tina; Hiskia, Anastasia; Haande, Sigrid; Skjelbred, Birger; Madrecka, Beata; Nemova, Hana; Drastichova, Iveta; Chomova, Lucia; Edwards, Christine; Sevindik, Tuğba Ongun; Tunca, Hatice; Önem, Burçin; Aleksovski, Boris; Krstić, Svetislav; Vucelić, Itana Bokan; Nawrocka, Lidia; Salmi, Pauliina; Machado-Vieira, Danielle; de Oliveira, Alinne Gurjão; Delgado-Martín, Jordi; García, David; Cereijo, Jose Luís; Trapote, Mari Carmen; Obrador, Biel; Grabowska, Magdalena; Chmura, Damian; Úbeda, Bárbara; Warming, Trine Perlt; Kobos, Justyna; Mazur-Marzec, Hanna; Arvola, Lauri; Alcaraz-Párraga, Pablo; Toporowska, Magdalena; Pawlik-Skowronska, Barbara; Niedźwiecki, Michał; Pęczuła, Wojciech; Moreno-Ostos, Enrique; Blanco, José María; Rodríguez, Valeriano; Montes-Pérez, Jorge Juan; Palomino, Roberto L.; Rodríguez-Pérez, Estela; Carballeira, Rafael; Picazo, Antonio; Santamans, Anna C.; Ferriol, Carmen; Romo, Susana; Dunalska, Julita; Sieńska, Justyna; Szymański, Daniel; Kostrzewska-Szlakowska, Iwona; Jasser, Iwona; Žutinić, Petar; Udovič, Marija Gligora; Plenković-Moraj, Anđelka; Frąk, Magdalena; Bańkowska-Sobczak, Agnieszka; Wasilewicz, Michał; Özkan, Korhan; Kangro, Kersti; Ibelings, Bas W.

2018-01-01

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. PMID:29652856

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins.

PubMed

Mantzouki, Evanthia; Lürling, Miquel; Fastner, Jutta; de Senerpont Domis, Lisette; Wilk-Woźniak, Elżbieta; Koreivienė, Judita; Seelen, Laura; Teurlincx, Sven; Verstijnen, Yvon; Krztoń, Wojciech; Walusiak, Edward; Karosienė, Jūratė; Kasperovičienė, Jūratė; Savadova, Ksenija; Vitonytė, Irma; Cillero-Castro, Carmen; Budzyńska, Agnieszka; Goldyn, Ryszard; Kozak, Anna; Rosińska, Joanna; Szeląg-Wasielewska, Elżbieta; Domek, Piotr; Jakubowska-Krepska, Natalia; Kwasizur, Kinga; Messyasz, Beata; Pełechaty, Aleksandra; Pełechaty, Mariusz; Kokocinski, Mikolaj; García-Murcia, Ana; Real, Monserrat; Romans, Elvira; Noguero-Ribes, Jordi; Duque, David Parreño; Fernández-Morán, Elísabeth; Karakaya, Nusret; Häggqvist, Kerstin; Demir, Nilsun; Beklioğlu, Meryem; Filiz, Nur; Levi, Eti E.; Iskin, Uğur; Bezirci, Gizem; Tavşanoğlu, Ülkü Nihan; Özhan, Koray; Gkelis, Spyros; Panou, Manthos; Fakioglu, Özden; Avagianos, Christos; Kaloudis, Triantafyllos; Çelik, Kemal; Yilmaz, Mete; Marcé, Rafael; Catalán, Nuria; Bravo, Andrea G.; Buck, Moritz; Colom-Montero, William; Mustonen, Kristiina; Pierson, Don; Yang, Yang; Raposeiro, Pedro M.; Gonçalves, Vítor; Antoniou, Maria G.; Tsiarta, Nikoletta; McCarthy, Valerie; Perello, Victor C.; Feldmann, Tõnu; Laas, Alo; Panksep, Kristel; Tuvikene, Lea; Gagala, Ilona; Mankiewicz-Boczek, Joana; Yağcı, Meral Apaydın; Çınar, Şakir; Çapkın, Kadir; Yağcı, Abdulkadir; Cesur, Mehmet; Bilgin, Fuat; Bulut, Cafer; Uysal, Rahmi; Obertegger, Ulrike; Boscaini, Adriano; Flaim, Giovanna; Salmaso, Nico; Cerasino, Leonardo; Richardson, Jessica; Visser, Petra M.; Verspagen, Jolanda M. H.; Karan, Tünay; Soylu, Elif Neyran; Maraşlıoğlu, Faruk; Napiórkowska-Krzebietke, Agnieszka; Ochocka, Agnieszka; Pasztaleniec, Agnieszka; Antão-Geraldes, Ana M.; Vasconcelos, Vitor; Morais, João; Vale, Micaela; Köker, Latife; Akçaalan, Reyhan; Albay, Meriç; Špoljarić Maronić, Dubravka; Stević, Filip; Žuna Pfeiffer, Tanja; Fonvielle, Jeremy; Straile, Dietmar; Rothhaupt, Karl-Otto; Hansson, Lars-Anders; Urrutia-Cordero, Pablo; Bláha, Luděk; Geriš, Rodan; Fránková, Markéta; Koçer, Mehmet Ali Turan; Alp, Mehmet Tahir; Remec-Rekar, Spela; Elersek, Tina; Triantis, Theodoros; Zervou, Sevasti-Kiriaki; Hiskia, Anastasia; Haande, Sigrid; Skjelbred, Birger; Madrecka, Beata; Nemova, Hana; Drastichova, Iveta; Chomova, Lucia; Edwards, Christine; Sevindik, Tuğba Ongun; Tunca, Hatice; Önem, Burçin; Aleksovski, Boris; Krstić, Svetislav; Vucelić, Itana Bokan; Nawrocka, Lidia; Salmi, Pauliina; Machado-Vieira, Danielle; de Oliveira, Alinne Gurjão; Delgado-Martín, Jordi; García, David; Cereijo, Jose Luís; Gomà, Joan; Trapote, Mari Carmen; Vegas-Vilarrúbia, Teresa; Obrador, Biel; Grabowska, Magdalena; Karpowicz, Maciej; Chmura, Damian; Úbeda, Bárbara; Gálvez, José Ángel; Özen, Arda; Christoffersen, Kirsten Seestern; Warming, Trine Perlt; Kobos, Justyna; Mazur-Marzec, Hanna; Pérez-Martínez, Carmen; Ramos-Rodríguez, Eloísa; Arvola, Lauri; Alcaraz-Párraga, Pablo; Toporowska, Magdalena; Pawlik-Skowronska, Barbara; Niedźwiecki, Michał; Pęczuła, Wojciech; Leira, Manel; Hernández, Armand; Moreno-Ostos, Enrique; Blanco, José María; Rodríguez, Valeriano; Montes-Pérez, Jorge Juan; Palomino, Roberto L.; Rodríguez-Pérez, Estela; Carballeira, Rafael; Camacho, Antonio; Picazo, Antonio; Rochera, Carlos; Santamans, Anna C.; Ferriol, Carmen; Romo, Susana; Soria, Juan Miguel; Dunalska, Julita; Sieńska, Justyna; Szymański, Daniel; Kruk, Marek; Kostrzewska-Szlakowska, Iwona; Jasser, Iwona; Žutinić, Petar; Gligora Udovič, Marija; Plenković-Moraj, Anđelka; Frąk, Magdalena; Bańkowska-Sobczak, Agnieszka; Wasilewicz, Michał; Özkan, Korhan; Maliaka, Valentini; Kangro, Kersti; Grossart, Hans-Peter; Paerl, Hans W.; Carey, Cayelan C.; Ibelings, Bas W.

2018-04-13

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.

Biophysical model of prokaryotic diversity in geothermal hot springs.

PubMed

Klales, Anna; Duncan, James; Nett, Elizabeth Janus; Kane, Suzanne Amador

2012-02-01

Recent studies of photosynthetic bacteria living in geothermal hot spring environments have revealed surprisingly complex ecosystems with an unexpected level of genetic diversity. One case of particular interest involves the distribution along hot spring thermal gradients of genetically distinct bacterial strains that differ in their preferred temperatures for reproduction and photosynthesis. In such systems, a single variable, temperature, defines the relevant environmental variation. In spite of this, each region along the thermal gradient exhibits multiple strains of photosynthetic bacteria adapted to several distinct thermal optima, rather than a single thermal strain adapted to the local environmental temperature. Here we analyze microbiology data from several ecological studies to show that the thermal distribution data exhibit several universal features independent of location and specific bacterial strain. These include the distribution of optimal temperatures of different thermal strains and the functional dependence of the net population density on temperature. We present a simple population dynamics model of these systems that is highly constrained by biophysical data and by physical features of the environment. This model can explain in detail the observed thermal population distributions, as well as certain features of population dynamics observed in laboratory studies of the same organisms. © 2012 American Physical Society

Impact of climate variability on the transmission risk of malaria in northern Côte d'Ivoire.

PubMed

M'Bra, Richard K; Kone, Brama; Soro, Dramane P; N'krumah, Raymond T A S; Soro, Nagnin; Ndione, Jacques A; Sy, Ibrahima; Ceccato, Pietro; Ebi, Kristie L; Utzinger, Jürg; Schindler, Christian; Cissé, Guéladio

2018-01-01

Since the 1970s, the northern part of Côte d'Ivoire has experienced considerable fluctuation in its meteorology including a general decrease of rainfall and increase of temperature from 1970 to 2000, a slight increase of rainfall since 2000, a severe drought in 2004-2005 and flooding in 2006-2007. Such changing climate patterns might affect the transmission of malaria. The purpose of this study was to analyze climate and environmental parameters associated with malaria transmission in Korhogo, a city in northern Côte d'Ivoire. All data were collected over a 10-year period (2004-2013). Rainfall, temperature and Normalized Difference Vegetation Index (NDVI) were the climate and environmental variables considered. Association between these variables and clinical malaria data was determined, using negative binomial regression models. From 2004 to 2013, there was an increase in the annual average precipitation (1100.3-1376.5 mm) and the average temperature (27.2°C-27.5°C). The NDVI decreased from 0.42 to 0.40. We observed a strong seasonality in these climatic variables, which resembled the seasonality in clinical malaria. An incremental increase of 10 mm of monthly precipitation was, on average, associated with a 1% (95% Confidence interval (CI): 0.7 to 1.2%) and a 1.2% (95% CI: 0.9 to 1.5%) increase in the number of clinical malaria episodes one and two months later respectively. A 1°C increase in average monthly temperature was, on average, associated with a decline of a 3.5% (95% CI: 0.1 to 6.7%) in clinical malaria episodes. A 0.1 unit increase in monthly NDVI was associated with a 7.3% (95% CI: 0.8 to 14.1%) increase in the monthly malaria count. There was a similar increase for the preceding-month lag (6.7% (95% CI: 2.3% to 11.2%)). The study results can be used to establish a malaria early warning system in Korhogo to prepare for outbreaks of malaria, which would increase community resilience no matter the magnitude and pattern of climate change.

Awareness of Environmental Change, Climate Variability, and Their Role in Prevalence of Mosquitoes among Urban Dwellers in Southern Ghana.

PubMed

Mattah, Precious Agbeko Dzorgbe; Futagbi, Godfred; Mattah, Memuna Mawusi

2018-01-01

This study evaluates the extent to which urban residents of Accra and Sekondi-Takoradi (all of southern Ghana) were aware of environment and climate-related variability. A total of 150 questionnaires were given to adults of 40 years and above who lived in the cities for at least 35 years. SPSS version 16 was used to process the data. Results show that all respondents in Accra Metropolitan Area (AMA) and 96% of them in Sekondi-Takoradi Metropolitan Area (STMA) noted the deteriorating vegetation cover over the cities. Similarly, 93% and 83% of them in AMA and STMA, respectively, observed that land use pattern of the two cities has changed considerably. There was positive and statistically significant correlation between respondents' educational attainment and their awareness of changes in land use/land cover ( r = 0.18, n = 140, p = 0.03). Also, 71% in AMA and 89% in STMA stated that temperature of the cities had been increasing over the years. In all, 82.9% of the respondents mentioned that they had problem with the increasing population of mosquitoes. Respondents demonstrated ample knowledge of environment and climate variability and should be engaged in preventing further environmental degradation. The top-down approach to environmental issues has failed; the bottom-up approach to environmental maintenance is needed.

Estimating the effect of multiple environmental stressors on coral bleaching and mortality.

PubMed

Welle, Paul D; Small, Mitchell J; Doney, Scott C; Azevedo, Inês L

2017-01-01

Coral cover has been declining in recent decades due to increased temperatures and environmental stressors. However, the extent to which different stressors contribute both individually and in concert to bleaching and mortality is still very uncertain. We develop and use a novel regression approach, using non-linear parametric models that control for unobserved time invariant effects to estimate the effects on coral bleaching and mortality due to temperature, solar radiation, depth, hurricanes and anthropogenic stressors using historical data from a large bleaching event in 2005 across the Caribbean. Two separate models are created, one to predict coral bleaching, and the other to predict near-term mortality. A large ensemble of supporting data is assembled to control for omitted variable bias and improve fit, and a significant improvement in fit is observed from univariate linear regression based on temperature alone. The results suggest that climate stressors (temperature and radiation) far outweighed direct anthropogenic stressors (using distance from shore and nearby human population density as a proxy for such stressors) in driving coral health outcomes during the 2005 event. Indeed, temperature was found to play a role ~4 times greater in both the bleaching and mortality response than population density across their observed ranges. The empirical models tested in this study have large advantages over ordinary-least squares-they offer unbiased estimates for censored data, correct for spatial correlation, and are capable of handling more complex relationships between dependent and independent variables. The models offer a framework for preparing for future warming events and climate change; guiding monitoring and attribution of other bleaching and mortality events regionally and around the globe; and informing adaptive management and conservation efforts.

Estimating the effect of multiple environmental stressors on coral bleaching and mortality

PubMed Central

Welle, Paul D.; Small, Mitchell J.; Doney, Scott C.; Azevedo, Inês L.

2017-01-01

Coral cover has been declining in recent decades due to increased temperatures and environmental stressors. However, the extent to which different stressors contribute both individually and in concert to bleaching and mortality is still very uncertain. We develop and use a novel regression approach, using non-linear parametric models that control for unobserved time invariant effects to estimate the effects on coral bleaching and mortality due to temperature, solar radiation, depth, hurricanes and anthropogenic stressors using historical data from a large bleaching event in 2005 across the Caribbean. Two separate models are created, one to predict coral bleaching, and the other to predict near-term mortality. A large ensemble of supporting data is assembled to control for omitted variable bias and improve fit, and a significant improvement in fit is observed from univariate linear regression based on temperature alone. The results suggest that climate stressors (temperature and radiation) far outweighed direct anthropogenic stressors (using distance from shore and nearby human population density as a proxy for such stressors) in driving coral health outcomes during the 2005 event. Indeed, temperature was found to play a role ~4 times greater in both the bleaching and mortality response than population density across their observed ranges. The empirical models tested in this study have large advantages over ordinary-least squares–they offer unbiased estimates for censored data, correct for spatial correlation, and are capable of handling more complex relationships between dependent and independent variables. The models offer a framework for preparing for future warming events and climate change; guiding monitoring and attribution of other bleaching and mortality events regionally and around the globe; and informing adaptive management and conservation efforts. PMID:28472031

Global map of solar power production efficiency, considering micro climate factors

NASA Astrophysics Data System (ADS)

Hassanpour Adeh, E.; Higgins, C. W.

2017-12-01

Natural resources degradation and greenhouse gas emissions are creating a global crisis. Renewable energy is the most reliable option to mitigate this environmental dilemma. Abundancy of solar energy makes it highly attractive source of electricity. The existing global spatial maps of available solar energy are created with various models which consider the irradiation, latitude, cloud cover, elevation, shading and aerosols, and neglect the influence of local meteorological conditions. In this research, the influences of microclimatological variables on solar energy productivity were investigated with an in-field study at the Rabbit Hills solar arrays near Oregon State University. The local studies were extended to a global level, where global maps of solar power were produced, taking the micro climate variables into account. These variables included: temperature, relative humidity, wind speed, wind direction, solar radiation. The energy balance approach was used to synthesize the data and compute the efficiencies. The results confirmed that the solar power efficiency can be directly affected by the air temperature and wind speed.

Diel Variability in Seawater pH Relates to Calcification and Benthic Community Structure on Coral Reefs

PubMed Central

Martz, Todd R.; Brainard, Russell E.

2012-01-01

Community structure and assembly are determined in part by environmental heterogeneity. While reef-building corals respond negatively to warming (i.e. bleaching events) and ocean acidification (OA), the extent of present-day natural variability in pH on shallow reefs and ecological consequences for benthic assemblages is unknown. We documented high resolution temporal patterns in temperature and pH from three reefs in the central Pacific and examined how these data relate to community development and net accretion rates of early successional benthic organisms. These reefs experienced substantial diel fluctuations in temperature (0.78°C) and pH (>0.2) similar to the magnitude of ‘warming’ and ‘acidification’ expected over the next century. Where daily pH within the benthic boundary layer failed to exceed pelagic climatological seasonal lows, net accretion was slower and fleshy, non-calcifying benthic organisms dominated space. Thus, key aspects of coral reef ecosystem structure and function are presently related to natural diurnal variability in pH. PMID:22952785

The Relationship between Phytoplankton Distribution and Water Column Characteristics in North West European Shelf Sea Waters

PubMed Central

Davidson, Keith; Bolch, Christopher J. S.; Brand, Tim D.; Narayanaswamy, Bhavani E.

2012-01-01

Phytoplankton underpin the marine food web in shelf seas, with some species having properties that are harmful to human health and coastal aquaculture. Pressures such as climate change and anthropogenic nutrient input are hypothesized to influence phytoplankton community composition and distribution. Yet the primary environmental drivers in shelf seas are poorly understood. To begin to address this in North Western European waters, the phytoplankton community composition was assessed in light of measured physical and chemical drivers during the “Ellett Line” cruise of autumn 2001 across the Scottish Continental shelf and into adjacent open Atlantic waters. Spatial variability existed in both phytoplankton and environmental conditions, with clear differences not only between on and off shelf stations but also between different on shelf locations. Temperature/salinity plots demonstrated different water masses existed in the region. In turn, principal component analysis (PCA), of the measured environmental conditions (temperature, salinity, water density and inorganic nutrient concentrations) clearly discriminated between shelf and oceanic stations on the basis of DIN∶DSi ratio that was correlated with both salinity and temperature. Discrimination between shelf stations was also related to this ratio, but also the concentration of DIN and DSi. The phytoplankton community was diatom dominated, with multidimensional scaling (MDS) demonstrating spatial variability in its composition. Redundancy analysis (RDA) was used to investigate the link between environment and the phytoplankton community. This demonstrated a significant relationship between community composition and water mass as indexed by salinity (whole community), and both salinity and DIN∶DSi (diatoms alone). Diatoms of the Pseudo-nitzschia seriata group occurred at densities potentially harmful to shellfish aquaculture, with the potential for toxicity being elevated by the likelihood of DSi limitation of growth at most stations and depths. PMID:22479533

Spatial correlations of population and ecological factors with distribution of visceral leishmaniasis cases in southwestern Iran.

PubMed

Ghatee, Mohammad Amin; Sharifi, Iraj; Haghdoost, Ali Akbar; Kanannejad, Zahra; Taabody, Zahra; Hatam, Gholamreza; Abdollahipanah, Abbas

2013-09-01

Leishmaniasis as a dynamic disease may be markedly influenced by demographic and ecological factors. A geospatial information system study was developed to determine the distribution of visceral leishmaniasis (VL) cases in relation to population, climatic and environmental factors in Fars province, southwest of Iran. The dwelling addresses of 217 VL patients were obtained from hospital files. A hazard map produced by unifying buffers (5 km) around nomads travel routes (NTR) was developed to survey the effect of close proximity to NTR on the distribution of VL. Mean annual rainfall (MAR), mean annual temperature (MAT), four months temperature mean (T4), elevation, slope and landcover were climatic and environmental factors that have been analysed. Finally, data of dwelling foci were extracted from maps and analysed using logistic regression models. Close proximity to NTR was the most important factor influenced on the disease distribution. Climatic factors were in second rank. Among them, temperature especially T4 is the most effective variable and rainfall was also shown to be another effective climatic agent. Most cases of VL were reported from temperate and semiarid areas in western and central regions while arid condition was a confined factor. The environmental factor of landcovers including urban, dry farm and thin forest regions was revealed as the third rank effective factor. Altitude importance was only shown when its effect was studied independently from other factors. These findings present the distribution of VL in Fars province is influenced by combination of ecological and nomads demographical variables although closeness to NTR and nomads role in distribution and continuance of kala-azar are the most important factors.

Environmental influences on potential recruitment of pink shrimp, Fatlantopenaeus duorarum, from Florida Bay nursery grounds

USGS Publications Warehouse

Browder, Joan A.; Restrepo, V.R.; Rice, J.K.; Robblee, M.B.; Zein-Eldin, Z.

1999-01-01

Two modeling approaches were used to explore the basis for variation in recruitment of pink shrimp, Farfantepenaeus duorarum, to the Tortugas fishing grounds. Emphasis was on development and juvenile densities on the nursery grounds. An exploratory simulation modeling exercise demonstrated large year-to-year variations in recruitment contributions to the Tortugas rink shrimp fishery may occur on some nursery grounds, and production may differ considerably among nursery grounds within the same year, simply on the basis of differences in temperature and salinity. We used a growth and survival model to simulate cumulative harvests from a July-centered cohort of early-settlement-stage postlarvae from two parts of Florida Bay (western Florida Bay and northcentral Florida Bay), using historic temperature and salinity data from these areas. Very large year-to-year differences in simulated cumulative harvests were found for recruits from Whipray Basin. Year-to-year differences in simulated harvests of recruits from Johnson Key Basin were much smaller. In a complementary activity, generalized linear and additive models and intermittent, historic density records were used to develop an uninterrupted multi-year time series of monthly density estimates for juvenile rink shrimp in the Johnson Key Basin. The developed data series was based on relationships of density with environmental variables. The strongest relationship was with sea-surface temperature. Three other environmental variables (rainfall, water level at Everglades National Park Well P35, and mean wind speed) also contributed significantly to explaining variation in juvenile densities. Results of the simulation model and two of the three statistical models yielded similar interannual patterns for Johnson Key Basin. While it is not possible to say that one result validates the other, the concordance of the annual patterns from the two models is supportive of both approaches.

Temporal variability of the quality of Taraxacum officinale seed progeny from the East-Ural radioactive trace: is there an interaction between low level radiation and weather conditions?

PubMed

Pozolotina, Vera N; Antonova, Elena V

2017-03-01

The multiple stressors, in different combinations, may impact differently upon seed quality, and low-level doses of radiation may enhance synergistic or antagonistic effects. During 1991-2014 we investigated the quality of the dandelion (Taraxacum officinale s.l.) seed progeny growing under low-level radiation exposure at the East-Ural Radioactive Trace (EURT) area (result of the Kyshtym accident, Russia), and in plants from areas exposed to background radiation. The viability of the dandelion seed progeny was assessed according to chronic radiation exposure, accounting for the variability of weather conditions among years. Environmental factors (temperature, precipitation, and their ratio in different months) can modify the radiobiological effects. We found a wide range of possible responses to multiple stressors: inhibition, stimulation, and indifferent effects in different seasons. The intraspecific variability of the quality of dandelion seed progeny was greatly increased under conditions of low doses of chronic irradiation. Temperature was the most significant factor for seed progeny formation in the EURT zone, whereas the sums of precipitation and ratios of precipitation to temperature dominantly affected organisms from the background population.

Uncertainty in Model Predictions of Vibrio Vulnificus Response to Climate Variability and Change: A Chesapeake Bay Case Study

NASA Technical Reports Server (NTRS)

Urquhart, Erin A.; Zaitchik, Benjamin F.; Waugh, Darryn W.; Guikema, Seth D.; Del Castillo, Carlos E.

2014-01-01

The effect that climate change and variability will have on waterborne bacteria is a topic of increasing concern for coastal ecosystems, including the Chesapeake Bay. Surface water temperature trends in the Bay indicate a warming pattern of roughly 0.3-0.4 C per decade over the past 30 years. It is unclear what impact future warming will have on pathogens currently found in the Bay, including Vibrio spp. Using historical environmental data, combined with three different statistical models of Vibrio vulnificus probability, we explore the relationship between environmental change and predicted Vibrio vulnificus presence in the upper Chesapeake Bay. We find that the predicted response of V. vulnificus probability to high temperatures in the Bay differs systematically between models of differing structure. As existing publicly available datasets are inadequate to determine which model structure is most appropriate, the impact of climatic change on the probability of V. vulnificus presence in the Chesapeake Bay remains uncertain. This result points to the challenge of characterizing climate sensitivity of ecological systems in which data are sparse and only statistical models of ecological sensitivity exist.

Landscape-scale processes influence riparian plant composition along a regulated river

USGS Publications Warehouse

Palmquist, Emily C.; Ralston, Barbara; Merritt, David M.; Shafroth, Patrick B.

2018-01-01

Hierarchical frameworks are useful constructs when exploring landscape- and local-scale factors affecting patterns of vegetation in riparian areas. In drylands, which have steep environmental gradients and high habitat heterogeneity, landscape-scale variables, such as climate, can change rapidly along a river's course, affecting the relative influence of environmental variables at different scales. To assess how landscape-scale factors change the structure of riparian vegetation, we measured riparian vegetation composition along the Colorado River through Grand Canyon, determined which factors best explain observed changes, identified how richness and functional diversity vary, and described the implications of our results for river management. Cluster analysis identified three divergent floristic groups that are distributed longitudinally along the river. These groups were distributed along gradients of elevation, temperature and seasonal precipitation, but were not associated with annual precipitation or local-scale factors. Species richness and functional diversity decreased as a function of distance downstream showing that changing landscape-scale factors result in changes to ecosystem characteristics. Species composition and distribution remain closely linked to seasonal precipitation and temperature. These patterns in floristic composition in a semiarid system inform management and provide insights into potential future changes as a result of shifts in climate and changes in flow management.

Assessment of PDMS-water partition coefficients: implications for passive environmental sampling of hydrophobic organic compounds

USGS Publications Warehouse

DiFilippo, Erica L.; Eganhouse, Robert P.

2010-01-01

Solid-phase microextraction (SPME) has shown potential as an in situ passive-sampling technique in aquatic environments. The reliability of this method depends upon accurate determination of the partition coefficient between the fiber coating and water (Kf). For some hydrophobic organic compounds (HOCs), Kf values spanning 4 orders of magnitude have been reported for polydimethylsiloxane (PDMS) and water. However, 24% of the published data examined in this review did not pass the criterion for negligible depletion, resulting in questionable Kf values. The range in reported Kf is reduced to just over 2 orders of magnitude for some polychlorinated biphenyls (PCBs) when these questionable values are removed. Other factors that could account for the range in reported Kf, such as fiber-coating thickness and fiber manufacturer, were evaluated and found to be insignificant. In addition to accurate measurement of Kf, an understanding of the impact of environmental variables, such as temperature and ionic strength, on partitioning is essential for application of laboratory-measured Kf values to field samples. To date, few studies have measured Kf for HOCs at conditions other than at 20 degrees or 25 degrees C in distilled water. The available data indicate measurable variations in Kf at different temperatures and different ionic strengths. Therefore, if the appropriate environmental variables are not taken into account, significant error will be introduced into calculated aqueous concentrations using this passive sampling technique. A multiparameter linear solvation energy relationship (LSER) was developed to estimate log Kf in distilled water at 25 degrees C based on published physicochemical parameters. This method provided a good correlation (R2 = 0.94) between measured and predicted log Kf values for several compound classes. Thus, an LSER approach may offer a reliable means of predicting log Kf for HOCs whose experimental log Kf values are presently unavailable. Future research should focus on understanding the impact of environmental variables on Kf. Obtaining the data needed for an LSER approach to estimate Kf for all environmentally relevant HOCs would be beneficial to the application of SPME as a passive-sampling technique.

Warming set stage for deadly heat wave

NASA Astrophysics Data System (ADS)

Schultz, Colin

2012-04-01

In the summer of 2010, soaring temperatures and widespread forest fires ravaged western Russia, killing 55,000 and causing $15 billion in economic losses. In the wake of the record-setting heat wave, two studies sought to identify the contribution that human activities made to the event. One showed that temperatures seen during the deadly heat wave fell within the bounds of natural variability, while another attributed the heat wave to human activity, arguing that anthropogenic warming increased the chance of record-breaking temperatures occurring. Merging the stances of both studies, Otto et al. sought to show that while human contributions to climate change did not necessarily cause the deadly heat wave, they did play a role in setting the stage for its occurrence. Using an ensemble of climate simulations, the authors assessed the expected magnitude and frequency of an event like the 2010 heat wave under both 1960s and 2000s environmental conditions. The authors found that although the average temperature in July 2010 was 5°C higher than the average July temperature from the past half decade, the deadly heat wave was within the natural variability of 1960s, as well as 2000s, climate conditions

Time Series Analysis of Cholera in Matlab, Bangladesh, during 1988-2001

PubMed Central

Kim, Deok Ryun; Yunus, Mohammad; Emch, Michael

2013-01-01

The study examined the impact of in-situ climatic and marine environmental variability on cholera incidence in an endemic area of Bangladesh and developed a forecasting model for understanding the magnitude of incidence. Diarrhoea surveillance data collected between 1988 and 2001were obtained from a field research site in Matlab, Bangladesh. Cholera cases were defined as Vibrio cholerae O1 isolated from faecal specimens of patients who sought care at treatment centres serving the Matlab population. Cholera incidence for 168 months was correlated with remotely-sensed sea-surface temperature (SST) and in-situ environmental data, including rainfall and ambient temperature. A seasonal autoregressive integrated moving average (SARIMA) model was used for determining the impact of climatic and environmental variability on cholera incidence and evaluating the ability of the model to forecast the magnitude of cholera. There were 4,157 cholera cases during the study period, with an average of 1.4 cases per 1,000 people. Since monthly cholera cases varied significantly by month, it was necessary to stabilize the variance of cholera incidence by computing the natural logarithm to conduct the analysis. The SARIMA model shows temporal clustering of cholera at one- and 12-month lags. There was a 6% increase in cholera incidence with a minimum temperature increase of one degree celsius in the current month. For increase of SST by one degree celsius, there was a 25% increase in the cholera incidence at currrent month and 18% increase in the cholera incidence at two months. Rainfall did not influenc to cause variation in cholera incidence during the study period. The model forecast the fluctuation of cholera incidence in Matlab reasonably well (Root mean square error, RMSE: 0.108). Thus, the ambient and sea-surface temperature-based model could be used in forecasting cholera outbreaks in Matlab. PMID:23617200

Investigating the link between fish community structure and environmental state in deep-time

NASA Astrophysics Data System (ADS)

Sibert, E. C.

2017-12-01

In the modern ocean, a bottom-up ecological viewpoint posits that the composition of plankton communities is often a function of ambient oceanographic conditions, including nutrient concentrations and water temperature. Thus, certain plankton species or communities can be associated with specific oceanographic conditions, giving them potential as carriers of paleoceanographic information. Furthermore, consumer groups, such as fish, depend on the structure and composition of these plankton, and therefore different plankton communities will support different types of fish. In addition, fish have their own physiological constraints for surviving in particular environments, such as oxygen demand, and metabolic rate, causing certain clades to be selectively associated with different water mass characteristics. Thus, the relative or absolute abundances of different fish species or groups could shed light on shifting oxygen concentrations, temperature, or primary productivity in the past. To assess whether fish communities have sufficient environmental control to provide paleoceanographic insights, I use a variety of morphological, phylogenetic, and ecological statistical approaches, to correlate modern fish communities from around the world with environmental variables. I then apply these principles to a series of ichthyolith assemblages from the Cretaceous and Cenozoic, across both space and time, to assess whether fish community composition, abundance, or other characteristics can be predictive of ocean temperature or export productivity. I find that while the abundance of fish fossils in deep-sea cores is often, though not always, correlated with certain export production and temperature proxies, community composition appears to vary independently of these variables on long timescales, driven more by evolutionary processes. However, there are distinct differences in contemporary communities in different locations, suggesting that there is potential in using fish community composition in well-constrained systems. Furthermore, when fish community structure or abundance diverges from the expected state, this may provide significant insight into the structure and functioning of marine ecosystems.

Field Metabolic Rate Is Dependent on Time-Activity Budget in Ring-Billed Gulls (Larus delawarensis) Breeding in an Anthropogenic Environment.

PubMed

Marteinson, Sarah C; Giroux, Jean-François; Hélie, Jean-François; Gentes, Marie-Line; Verreault, Jonathan

2015-01-01

Environmental and behavioral factors have long been assumed to affect variation in avian field metabolic rate (FMR). However, due to the difficulties in measuring continuous behavior of birds over prolonged periods of time, complete time-activity budgets have rarely been examined in relation to FMR. Our objective was to determine the effect of activity (measured by detailed time-activity budgets) and a series of extrinsic and intrinsic factors on FMR of the omnivorous ring-billed gull (Larus delawarensis). The experiment was conducted during the incubation period when both members of the pair alternate between attending the nest-site and leaving the colony to forage in aquatic and anthropogenic environments (city, agricultural). FMR was determined using the doubly labeled water method. Time-activity budgets were extrapolated from spatio-temporal data (2-5 days) obtained from bird-borne GPS data loggers. Gulls had low FMRs compared to those predicted by allometric equations based on recorded FMRs from several seabird species. Gulls proportioned their time mainly to nest-site attendance (71% of total tracking time), which reduced FMR/g body mass, and was the best variable explaining energy expenditure. The next best variable was the duration of foraging trips, which increased FMR/g; FMR/g was also elevated by the proportion of time spent foraging or flying (17% and 8% of tracking time respectively). Most environmental variables measured did not impact FMR/g, however, the percent of time birds were subjected to temperatures below their lower critical temperature increased FMR. Time-activity budgets varied between the sexes, and with temperature and capture date suggesting that these variables indirectly affected FMR/g. The gulls foraged preferentially in anthropogenic-related habitats, which may have contributed to their low FMR/g due to the high availability of protein- and lipid-rich foods. This study demonstrates that activities were the best predictors of FMR/g in ring-billed gulls, thus providing strong support for this long-standing theory in bioenergetics.

Why did bluetongue spread the way it did? Environmental factors influencing the velocity of bluetongue virus serotype 8 epizootic wave in France.

PubMed

Pioz, Maryline; Guis, Hélène; Crespin, Laurent; Gay, Emilie; Calavas, Didier; Durand, Benoît; Abrial, David; Ducrot, Christian

2012-01-01

Understanding where and how fast an infectious disease will spread during an epidemic is critical for its control. However, the task is a challenging one as numerous factors may interact and drive the spread of a disease, specifically when vector-borne diseases are involved. We advocate the use of simultaneous autoregressive models to identify environmental features that significantly impact the velocity of disease spread. We illustrate this approach by exploring several environmental factors influencing the velocity of bluetongue (BT) spread in France during the 2007-2008 epizootic wave to determine which ones were the most important drivers. We used velocities of BT spread estimated in 4,495 municipalities and tested sixteen covariates defining five thematic groups of related variables: elevation, meteorological-related variables, landscape-related variables, host availability, and vaccination. We found that ecological factors associated with vector abundance and activity (elevation and meteorological-related variables), as well as with host availability, were important drivers of the spread of the disease. Specifically, the disease spread more slowly in areas with high elevation and when heavy rainfall associated with extreme temperature events occurred one or two months prior to the first clinical case. Moreover, the density of dairy cattle was correlated negatively with the velocity of BT spread. These findings add substantially to our understanding of BT spread in a temperate climate. Finally, the approach presented in this paper can be used with other infectious diseases, and provides a powerful tool to identify environmental features driving the velocity of disease spread.

Why Did Bluetongue Spread the Way It Did? Environmental Factors Influencing the Velocity of Bluetongue Virus Serotype 8 Epizootic Wave in France

PubMed Central

Pioz, Maryline; Guis, Hélène; Crespin, Laurent; Gay, Emilie; Calavas, Didier; Durand, Benoît; Abrial, David; Ducrot, Christian

2012-01-01

Understanding where and how fast an infectious disease will spread during an epidemic is critical for its control. However, the task is a challenging one as numerous factors may interact and drive the spread of a disease, specifically when vector-borne diseases are involved. We advocate the use of simultaneous autoregressive models to identify environmental features that significantly impact the velocity of disease spread. We illustrate this approach by exploring several environmental factors influencing the velocity of bluetongue (BT) spread in France during the 2007–2008 epizootic wave to determine which ones were the most important drivers. We used velocities of BT spread estimated in 4,495 municipalities and tested sixteen covariates defining five thematic groups of related variables: elevation, meteorological-related variables, landscape-related variables, host availability, and vaccination. We found that ecological factors associated with vector abundance and activity (elevation and meteorological-related variables), as well as with host availability, were important drivers of the spread of the disease. Specifically, the disease spread more slowly in areas with high elevation and when heavy rainfall associated with extreme temperature events occurred one or two months prior to the first clinical case. Moreover, the density of dairy cattle was correlated negatively with the velocity of BT spread. These findings add substantially to our understanding of BT spread in a temperate climate. Finally, the approach presented in this paper can be used with other infectious diseases, and provides a powerful tool to identify environmental features driving the velocity of disease spread. PMID:22916249

The Response of Environmental Capacity for Malaria Transmission in West Africa to Climate Change

NASA Astrophysics Data System (ADS)

Yamana, T. K.; Eltahir, E. A.

2011-12-01

The climate of West Africa is characterized by north-south gradients in temperature and rainfall. Environmental capacity for malaria transmission (e.g. as measured by vectorial capacity) is strongly tied to these two variables; temperature affects the development rate of the malaria parasite, as well as the lifespan of the mosquitoes that transmit the disease, and rainfall is tied to mosquito abundance, as the vector lays its eggs in rain-fed water pools. A change in climate is therefore expected to lead to changes in the distribution of malaria transmission. Current general circulation models agree that the temperature in West Africa is expected to increase by several degrees in the next century. However they predict a wide range of possible rainfall scenarios in the future, from intense drying to significant increases in rainfall (Christensen et al., 2007). The effects these changes will have on environmental capacity for malaria transmission depend on the magnitude and direction of the changes, and on current conditions. For example, malaria transmission will be more sensitive to positive changes in rainfall in dry areas where mosquito populations are currently limited by water availability than in relatively wet areas. Here, we analyze combinations of changes in rainfall and temperature within the ranges predicted by GCMs, and assess the impact these combinations will have on the environmental capacity for malaria transmission. In particular, we identify climate change scenarios that are likely to have the greatest impact on environmental capacity for malaria transmission, as well as geographic "hot spots" where the greatest changes are to be expected. Christensen, J. H., Busuioc, A., & et al. (2007). Regional climate projections. In S. Solomon (Ed.), Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.

Effects of Climate Change and Fisheries Bycatch on Shy Albatross (Thalassarche cauta) in Southern Australia

PubMed Central

2015-01-01

The impacts of climate change on marine species are often compounded by other stressors that make direct attribution and prediction difficult. Shy albatrosses (Thalassarche cauta) breeding on Albatross Island, Tasmania, show an unusually restricted foraging range, allowing easier discrimination between the influence of non-climate stressors (fisheries bycatch) and environmental variation. Local environmental conditions (rainfall, air temperature, and sea-surface height, an indicator of upwelling) during the vulnerable chick-rearing stage, have been correlated with breeding success of shy albatrosses. We use an age-, stage- and sex-structured population model to explore potential relationships between local environmental factors and albatross breeding success while accounting for fisheries bycatch by trawl and longline fisheries. The model uses time-series of observed breeding population counts, breeding success, adult and juvenile survival rates and a bycatch mortality observation for trawl fishing to estimate fisheries catchability, environmental influence, natural mortality rate, density dependence, and productivity. Observed at-sea distributions for adult and juvenile birds were coupled with reported fishing effort to estimate vulnerability to incidental bycatch. The inclusion of rainfall, temperature and sea-surface height as explanatory variables for annual chick mortality rate was statistically significant. Global climate models predict little change in future local average rainfall, however, increases are forecast in both temperatures and upwelling, which are predicted to have detrimental and beneficial effects, respectively, on breeding success. The model shows that mitigation of at least 50% of present bycatch is required to offset losses due to future temperature changes, even if upwelling increases substantially. Our results highlight the benefits of using an integrated modeling approach, which uses available demographic as well as environmental data within a single estimation framework, to provide future predictions. Such predictions inform the development of management options in the face of climate change. PMID:26057739

Effects of Climate Change and Fisheries Bycatch on Shy Albatross (Thalassarche cauta) in Southern Australia.

PubMed

Thomson, Robin B; Alderman, Rachael L; Tuck, Geoffrey N; Hobday, Alistair J

2015-01-01

The impacts of climate change on marine species are often compounded by other stressors that make direct attribution and prediction difficult. Shy albatrosses (Thalassarche cauta) breeding on Albatross Island, Tasmania, show an unusually restricted foraging range, allowing easier discrimination between the influence of non-climate stressors (fisheries bycatch) and environmental variation. Local environmental conditions (rainfall, air temperature, and sea-surface height, an indicator of upwelling) during the vulnerable chick-rearing stage, have been correlated with breeding success of shy albatrosses. We use an age-, stage- and sex-structured population model to explore potential relationships between local environmental factors and albatross breeding success while accounting for fisheries bycatch by trawl and longline fisheries. The model uses time-series of observed breeding population counts, breeding success, adult and juvenile survival rates and a bycatch mortality observation for trawl fishing to estimate fisheries catchability, environmental influence, natural mortality rate, density dependence, and productivity. Observed at-sea distributions for adult and juvenile birds were coupled with reported fishing effort to estimate vulnerability to incidental bycatch. The inclusion of rainfall, temperature and sea-surface height as explanatory variables for annual chick mortality rate was statistically significant. Global climate models predict little change in future local average rainfall, however, increases are forecast in both temperatures and upwelling, which are predicted to have detrimental and beneficial effects, respectively, on breeding success. The model shows that mitigation of at least 50% of present bycatch is required to offset losses due to future temperature changes, even if upwelling increases substantially. Our results highlight the benefits of using an integrated modeling approach, which uses available demographic as well as environmental data within a single estimation framework, to provide future predictions. Such predictions inform the development of management options in the face of climate change.

Individualized estimation of human core body temperature using noninvasive measurements.

PubMed

Laxminarayan, Srinivas; Rakesh, Vineet; Oyama, Tatsuya; Kazman, Josh B; Yanovich, Ran; Ketko, Itay; Epstein, Yoram; Morrison, Shawnda; Reifman, Jaques

2018-06-01

A rising core body temperature (T c ) during strenuous physical activity is a leading indicator of heat-injury risk. Hence, a system that can estimate T c in real time and provide early warning of an impending temperature rise may enable proactive interventions to reduce the risk of heat injuries. However, real-time field assessment of T c requires impractical invasive technologies. To address this problem, we developed a mathematical model that describes the relationships between T c and noninvasive measurements of an individual's physical activity, heart rate, and skin temperature, and two environmental variables (ambient temperature and relative humidity). A Kalman filter adapts the model parameters to each individual and provides real-time personalized T c estimates. Using data from three distinct studies, comprising 166 subjects who performed treadmill and cycle ergometer tasks under different experimental conditions, we assessed model performance via the root mean squared error (RMSE). The individualized model yielded an overall average RMSE of 0.33 (SD = 0.18)°C, allowing us to reach the same conclusions in each study as those obtained using the T c measurements. Furthermore, for 22 unique subjects whose T c exceeded 38.5°C, a potential lower T c limit of clinical relevance, the average RMSE decreased to 0.25 (SD = 0.20)°C. Importantly, these results remained robust in the presence of simulated real-world operational conditions, yielding no more than 16% worse RMSEs when measurements were missing (40%) or laden with added noise. Hence, the individualized model provides a practical means to develop an early warning system for reducing heat-injury risk. NEW & NOTEWORTHY A model that uses an individual's noninvasive measurements and environmental variables can continually "learn" the individual's heat-stress response by automatically adapting the model parameters on the fly to provide real-time individualized core body temperature estimates. This individualized model can replace impractical invasive sensors, serving as a practical and effective surrogate for core temperature monitoring.

Bivalves as indicators of environmental variation and potential anthropogenic impacts in the southern Barents Sea

PubMed Central

Carroll, Michael L.; Johnson, Beverly J.; Henkes, Gregory A.; McMahon, Kelton W.; Voronkov, Andrey; Ambrose, William G.; Denisenko, Stanislav G.

2009-01-01

Identifying patterns and drivers of natural variability in populations is necessary to gauge potential effects of climatic change and the expected increases in commercial activities in the Arctic on communities and ecosystems. We analyzed growth rates and shell geochemistry of the circumpolar Greenland smooth cockle, Serripes groenlandicus, from the southern Barents Sea over almost 70 years between 1882 and 1968. The datasets were calibrated via annually-deposited growth lines, and growth, stable isotope (δ18O, δ13C), and trace elemental (Mg, Sr, Ba, Mn) patterns were linked to environmental variations on weekly to decadal scales. Standardized growth indices revealed an oscillatory growth pattern with a multi-year periodicity, which was inversely related to the North Atlantic Oscillation Index (NAO), and positively related to local river discharge. Up to 60% of the annual variability in the Ba/Ca could be explained by variations in river discharge at the site closest to the rivers, but the relationship disappeared at a more distant location. Patterns of δ18O, δ13C, and Sr/Ca together provide evidence that bivalve growth ceases at elevated temperatures during the fall and recommences at the coldest temperatures in the early spring, with the implication that food, rather than temperature, is the primary driver of bivalve growth. The multi-proxy approach of combining the annually integrated information from the growth results and higher resolution geochemical results yielded a robust interpretation of biophysical coupling in the region over temporal and spatial scales. We thus demonstrate that sclerochronological proxies can be useful retrospective analytical tools for establishing a baseline of ecosystem variability in assessing potential combined impacts of climatic change and increasing commercial activities on Arctic communities. PMID:19394657

Does Day Length Affect Winter Bird Distribution? Testing the Role of an Elusive Variable

PubMed Central

Carrascal, Luis M.; Santos, Tomás; Tellería, José L.

2012-01-01

Differences in day length may act as a critical factor in bird biology by introducing time constraints in energy acquisition during winter. Thus, differences in day length might operate as a main determinant of bird abundance along latitudinal gradients. This work examines the influence of day length on the abundance of wintering crested tits (Lophophanes cristatus) in 26 localities of Spanish juniper (Juniperus thurifera) dwarf woodlands (average height of 5 m) located along a latitudinal gradient in the Spanish highlands, while controlling for the influence of food availability, minimum night temperature, habitat structure and landscape characteristics. Top regression models in the AIC framework explained 56% of variance in bird numbers. All models incorporated day length as the variable with the highest magnitude effect. Food availability also played an important role, although only the crop of ripe juniper fruits, but not arthropods, positively affected crested tit abundance. Differences in vegetation structure across localities had also a strong positive effect (average tree height and juniper tree density). Geographical variation in night temperature had no influence on crested tit distribution, despite the low winter temperatures reached in these dwarf forests. This paper demonstrates for the first time that winter bird abundance increases with day length after controlling for the effect of other environmental variables. Winter average difference in day length was only 10.5 minutes per day along the 1°47′ latitudinal interval (190 km) included in this study. This amount of time, which reaches 13.5 h accumulated throughout the winter season, appears to be large enough to affect the long-term energy budget of small passerines during winter and to shape the distribution of winter bird abundance under restrictive environmental conditions. PMID:22393442

The hour-to-hour influence of weather conditions on walking and cycling among Dutch older adults.

PubMed

Prins, Richard G; van Lenthe, F J

2015-09-01

physical activity (PA) is an important factor to promote healthy ageing. However, older adults are not physically active enough. Socio-ecological models suggest that weather conditions are determinants of PA and may bias relations between other environmental factors and PA. This may especially be the case for the most vulnerable and inactive older persons. Understanding the role of weather conditions is based on daily or seasonal variation in weather, but it can be improved by using hour-to-hour measured weather conditions. to study the hour-to-hour relationships between weather factors and objectively measured walking and cycling in a sample of Dutch older adults. baseline data (2013) of a sub-sample of older adults (3,248 observations clustered in 43 adults) participating in The Neighborhood Walking in Rotterdam Older ADultS (NEW.ROADS) trial were used. Participants wore a GPS logger for 7 consecutive days. Hour-to-hour weather data (temperature, wind speed, rain and sun time) for the city of Rotterdam were retrieved from the Royal Netherlands Meteorological Institute. Multilevel linear regression models were fitted with minutes walked and minutes cycled as dependent variables and the weather variables as independent variables. the time older adults walked increased with higher temperature, higher wind speed and the absence of rain. The time cycled increased with higher temperature. this study improves the evidence of weather factors as a determinant for walking and cycling in older adults. Studies on the relation between environmental factors and PA should consider adjustment for weather factors. © The Author 2015. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Variation in spawning time promotes genetic variability in population responses to environmental change in a marine fish

PubMed Central

Hutchings, Jeffrey A

2015-01-01

Abstract The level of phenotypic plasticity displayed within a population (i.e. the slope of the reaction norm) reflects the short-term response of a population to environmental change, while variation in reaction norm slopes among populations reflects spatial variation in these responses. Thus far, studies of thermal reaction norm variation have focused on geographically driven adaptation among different latitudes, altitudes or habitats. Yet, thermal variability is a function of both space and time. For organisms that reproduce at different times of year, such variation has the potential to promote adaptive variability in thermal responses for critical early life stages. Using common-garden experiments, we examined the spatial scale of genetic variation in thermal plasticity for early life-history traits among five populations of endangered Atlantic cod (Gadus morhua) that spawn at different times of year. Patterns of plasticity for larval growth and survival suggest that population responses to climate change will differ substantially, with increasing water temperatures posing a considerably greater threat to autumn-spawning cod than to those that spawn in winter or spring. Adaptation to seasonal cooling or warming experienced during the larval stage is suggested as a possible cause. Furthermore, populations that experience relatively cold temperatures during early life might be more sensitive to changes in temperature. Substantial divergence in adaptive traits was evident at a smaller spatial scale than has previously been shown for a marine fish with no apparent physical barriers to gene flow (∼200 km). Our findings highlight the need to consider the impact of intraspecific variation in reproductive timing on thermal adaptation when forecasting the effects of climate change on animal populations. PMID:27293712

Variation in spawning time promotes genetic variability in population responses to environmental change in a marine fish.

PubMed

Oomen, Rebekah A; Hutchings, Jeffrey A

2015-01-01

The level of phenotypic plasticity displayed within a population (i.e. the slope of the reaction norm) reflects the short-term response of a population to environmental change, while variation in reaction norm slopes among populations reflects spatial variation in these responses. Thus far, studies of thermal reaction norm variation have focused on geographically driven adaptation among different latitudes, altitudes or habitats. Yet, thermal variability is a function of both space and time. For organisms that reproduce at different times of year, such variation has the potential to promote adaptive variability in thermal responses for critical early life stages. Using common-garden experiments, we examined the spatial scale of genetic variation in thermal plasticity for early life-history traits among five populations of endangered Atlantic cod (Gadus morhua) that spawn at different times of year. Patterns of plasticity for larval growth and survival suggest that population responses to climate change will differ substantially, with increasing water temperatures posing a considerably greater threat to autumn-spawning cod than to those that spawn in winter or spring. Adaptation to seasonal cooling or warming experienced during the larval stage is suggested as a possible cause. Furthermore, populations that experience relatively cold temperatures during early life might be more sensitive to changes in temperature. Substantial divergence in adaptive traits was evident at a smaller spatial scale than has previously been shown for a marine fish with no apparent physical barriers to gene flow (∼200 km). Our findings highlight the need to consider the impact of intraspecific variation in reproductive timing on thermal adaptation when forecasting the effects of climate change on animal populations.

Niphargus: a silicon band-gap sensor temperature logger for high-precision environmental monitoring

NASA Astrophysics Data System (ADS)

Burlet, Christian; Vanbrabant, Yves; Piessens, Kris; Welkenhuysen, Kris; Verheyden, Sophie

2014-05-01

A temperature logger, called 'Niphargus', was developed at the Geological Survey of Belgium to monitor temperature of local natural processes with sensitivity of the order of a few hundredths of degrees to monitor temperature variability in open air, caves, soils and rivers. The newly developed instrument uses a state-of-the-art band-gap silicon temperature sensor with digital output. This sensor reduces the risk of drift associated with thermistor-based sensing devices, especially in humid environments. The Niphargus is designed to be highly reliable, low-cost and powered by a single lithium cell with up to several years autonomy depending on the sampling rate and environmental conditions. The Niphargus was evaluated in an ice point bath experiment in terms of temperature accuracy and thermal inertia. The small size and low power consumption of the logger allow its use in difficult accessible environments, e.g. caves and space-constrained applications, inside a rock in a water stream. In both cases, the loggers have proven to be reliable and accurate devices. For example, spectral analysis of the temperature signal in the Han caves (Belgium) allowed detection and isolation of a 0.005° C amplitude day-night periodic signal in the temperature curve. PIC Figure 1: a Niphargus logger in its standard size. SMD components side. Photo credit: W. Miseur

Seasonality of alcohol-related phenomena in Estonia.

PubMed

Silm, Siiri; Ahas, Rein

2005-03-01

We studied alcohol consumption and its consequences as a seasonal phenomenon in Estonia and analysed the social and environmental factors that may cause its seasonal rhythm. There are two important questions when researching the seasonality of human activities: (1) whether it is caused by natural or social factors, and (2) whether the impact of the factors is direct or indirect. Often the seasonality of social phenomena is caused by social factors, but the triggering mechanisms are related to environmental factors like temperature, precipitation, and radiation via the circannual calendar. The indicators of alcohol consumption in the current paper are grouped as: (1) pre-consumption phenomena, i.e. production, tax and excise, sales (beer, wine and vodka are analysed separately), and (2) post-consumption phenomena, i.e. alcohol-related crime and traffic accidents and the number of people detained in lockups and admitted to alcohol treatment clinics. In addition, seasonal variability in the amount of alcohol advertising has been studied, and a survey has been carried out among 87 students of Tartu University. The analysis shows that different phenomena related to alcohol have a clear seasonal rhythm in Estonia. The peak period of phenomena related to beer is in the summer, from June to August and the low point is during the first months of the year. Beer consumption correlates well with air temperature. The consumption of vodka increases sharply at the end of the year and in June; the production of vodka does not have a significant correlation with negative temperatures. The consumption of wine increases during summer and in December. The consequences of alcohol consumption, expressed as the rate of traffic accidents or the frequency of medical treatment, also show seasonal variability. Seasonal variability of alcohol consumption in Estonia is influenced by natural factors (temperature, humidity, etc.) and by social factors (celebrations, vacations, etc.). However, distinguishing between impacts of direct and indirect relationships is complicated, as they are interlinked.

Seasonality of alcohol-related phenomena in Estonia

NASA Astrophysics Data System (ADS)

Silm, Siiri; Ahas, Rein

2005-03-01

We studied alcohol consumption and its consequences as a seasonal phenomenon in Estonia and analysed the social and environmental factors that may cause its seasonal rhythm. There are two important questions when researching the seasonality of human activities: (1) whether it is caused by natural or social factors, and (2) whether the impact of the factors is direct or indirect. Often the seasonality of social phenomena is caused by social factors, but the triggering mechanisms are related to environmental factors like temperature, precipitation, and radiation via the circannual calendar. The indicators of alcohol consumption in the current paper are grouped as: (1) pre-consumption phenomena, i.e. production, tax and excise, sales (beer, wine and vodka are analysed separately), and (2) post-consumption phenomena, i.e. alcohol-related crime and traffic accidents and the number of people detained in lockups and admitted to alcohol treatment clinics. In addition, seasonal variability in the amount of alcohol advertising has been studied, and a survey has been carried out among 87 students of Tartu University. The analysis shows that different phenomena related to alcohol have a clear seasonal rhythm in Estonia. The peak period of phenomena related to beer is in the summer, from June to August and the low point is during the first months of the year. Beer consumption correlates well with air temperature. The consumption of vodka increases sharply at the end of the year and in June; the production of vodka does not have a significant correlation with negative temperatures. The consumption of wine increases during summer and in December. The consequences of alcohol consumption, expressed as the rate of traffic accidents or the frequency of medical treatment, also show seasonal variability. Seasonal variability of alcohol consumption in Estonia is influenced by natural factors (temperature, humidity, etc.) and by social factors (celebrations, vacations, etc.). However, distinguishing between impacts of direct and indirect relationships is complicated, as they are interlinked.

CO2 Flux From Antarctic Dry Valley Soils: Determining the Source and Environmental Controls

NASA Astrophysics Data System (ADS)

Risk, D. A.; Macintyre, C. M.; Shanhun, F.; Almond, P. C.; Lee, C.; Cary, C.

2014-12-01

Soils within the McMurdo Dry Valleys are known to respire carbon dioxide (CO2), but considerable debate surrounds the contributing sources and mechanisms that drive temporal variability. While some of the CO2 is of biological origin, other known contributors to variability include geochemical sources within, or beneath, the soil column. The relative contribution from each of these sources will depend on seasonal and environmental drivers such as temperature and wind that exert influence on temporal dynamics. To supplement a long term CO2­ surface flux monitoring station that has now recorded fluxes over three full annual cycles, in January 2014 an automated flux and depth concentration monitoring system was installed in the Spaulding Pond area of Taylor Valley, along with standard meteorological sensors, to assist in defining source contributions through time. During two weeks of data we observed marked diel variability in CO2 concentrations within the profile (~100 ppm CO2 above or below atmospheric), and of CO2 moving across the soil surface. The pattern at many depths suggested an alternating diel-scale transition from source to sink that seemed clearly correlated with temperature-driven changes in the solubility of CO2 in water films. This CO2 solution storage flux was very highly coupled to soil temperature. A small depth source of unknown origin also appeared to be present. A controlled laboratory soil experiment was conducted to confirm the magnitude of fluxes into and out of soil water films, and confirmed the field results and temperature dependence. Ultimately, this solution storage flux needs to be well understood if the small biological fluxes from these soils are to be properly quantified and monitored for change. Here, we present results from the 2013/2014 field season and these supplementary experiments, placed in the context of 3 year long term continuous measurement of soil CO2 flux within the Dry Valleys.

The use of simple physiological and environmental measures to estimate the latent heat transfer in crossbred Holstein cows

NASA Astrophysics Data System (ADS)

Santos, Severino Guilherme Caetano Gonçalves dos; Saraiva, Edilson Paes; Pimenta Filho, Edgard Cavalcanti; Gonzaga Neto, Severino; Fonsêca, Vinicus França Carvalho; Pinheiro, Antônio da Costa; Almeida, Maria Elivania Vieira; de Amorim, Mikael Leal Cabral Menezes

2017-02-01

The aim of the present study was to estimate the heat transfer through cutaneous and respiratory evaporation of dairy cows raised in tropical ambient conditions using simple environmental and physiological measures. Twenty-six lactating crossbred cows (7/8 Holstein-Gir) were used, 8 predominantly white and 18 predominantly black. The environmental variables air temperature, relative humidity, black globe temperature, and wind speed were measured. Respiratory rate and coat surface temperature were measured at 0700, 0900, 1100, 1300, and 1500 h. The environmental and physiological data were used to estimate heat loss by respiratory (ER) and cutaneous evaporation (EC). Results showed that there was variation ( P < 0.01) for respiratory rate depending on the times of the day. The highest values were recorded at 1100, 1300, and 1500 h, corresponding to 66.85 ± 10.20, 66.98 ± 7.80, and 65.65 ± 6.50 breaths/min, respectively. Thus, the amount of heat transferred via respiration ranged from 19.21 to 29.42 W/m2. There was a variation from 31.6 to 38.8 °C for coat surface temperature; these values reflected a range of 55.52 to 566.83 W/m2 for heat transfer via cutaneous evaporation. However, throughout the day, the dissipation of thermal energy through the coat surface accounted for 87.9 % total loss of latent heat, and the remainder (12.1 %) was via the respiratory tract. In conclusion, the predictive models based on respiratory rate and coat surface temperature may be used to estimate the latent heat loss in dairy cows kept confined in tropical ambient conditions.

Estimating enthalpy of vaporization from vapor pressure using Trouton's rule.

PubMed

MacLeod, Matthew; Scheringer, Martin; Hungerbühler, Konrad

2007-04-15

The enthalpy of vaporization of liquids and subcooled liquids at 298 K (delta H(VAP)) is an important parameter in environmental fate assessments that consider spatial and temporal variability in environmental conditions. It has been shown that delta H(VAP)P for non-hydrogen-bonding substances can be estimated from vapor pressure at 298 K (P(L)) using an empirically derived linear relationship. Here, we demonstrate that the relationship between delta H(VAP)and PL is consistent with Trouton's rule and the ClausiusClapeyron equation under the assumption that delta H(VAP) is linearly dependent on temperature between 298 K and the boiling point temperature. Our interpretation based on Trouton's rule substantiates the empirical relationship between delta H(VAP) degree and P(L) degrees for non-hydrogen-bonding chemicals with subcooled liquid vapor pressures ranging over 15 orders of magnitude. We apply the relationship between delta H(VAP) degrees and P(L) degrees to evaluate data reported in literature reviews for several important classes of semivolatile environmental contaminants, including polycyclic aromatic hydrocarbons, chlorobenzenes, polychlorinated biphenyls and polychlorinated dibenzo-dioxins and -furans and illustrate the temperature dependence of results from a multimedia model presented as a partitioning map. The uncertainty associated with estimating delta H(VAP)degrees from P(L) degrees using this relationship is acceptable for most environmental fate modeling of non-hydrogen-bonding semivolatile organic chemicals.

What is environmental stress? Insights from fish living in a variable environment.

PubMed

Schulte, Patricia M

2014-01-01

Although the term environmental stress is used across multiple fields in biology, the inherent ambiguity associated with its definition has caused confusion when attempting to understand organismal responses to environmental change. Here I provide a brief summary of existing definitions of the term stress, and the related concepts of homeostasis and allostasis, and attempt to unify them to develop a general framework for understanding how organisms respond to environmental stressors. I suggest that viewing stressors as environmental changes that cause reductions in performance or fitness provides the broadest and most useful conception of the phenomenon of stress. I examine this framework in the context of animals that have evolved in highly variable environments, using the Atlantic killifish, Fundulus heteroclitus, as a case study. Consistent with the extreme environmental variation that they experience in their salt marsh habitats, killifish have substantial capacity for both short-term resistance and long-term plasticity in the face of changing temperature, salinity and oxygenation. There is inter-population variation in the sensitivity of killifish to environmental stressors, and in their ability to acclimate, suggesting that local adaptation can shape the stress response even in organisms that are broadly tolerant and highly plastic. Whole-organism differences between populations in stressor sensitivity and phenotypic plasticity are reflected at the biochemical and molecular levels in killifish, emphasizing the integrative nature of the response to environmental stressors. Examination of this empirical example highlights the utility of using an evolutionary perspective on stressors, stress and stress responses.

Benthic macroinvertebrate assemblages and their relations with environmental variables in the Sacramento and San Joaquin River drainages, California, 1993-1997

USGS Publications Warehouse

Brown, Larry R.; May, Jason T.

2000-01-01

Data were collected in the San Joaquin and Sacramento river drainages to evaluate associations between macroinvertebrate assemblages and environmental variables as part of the National Water-Quality Assessment Program of the U.S. Geological Survey. Samples were collected at 53 sites from 1993 to 1995 in the San Joaquin River drainage and in 1996 and 1997 in the Sacramento River drainage. Macroinvertebrates were collected from riffles or from large woody debris (snags) when riffles were absent. Macroinvertebrate taxa were aggregated to the family (or higher) level of taxonomic organization, resulting in 81 taxa for analyses. Only the 50 most common taxa were used for two-way indicator species analysis (TWINSPAN) and canonical correspondence analysis. TWINSPAN analysis defined four groups of riffle samples and four groups of snag samples based on macroinvertebrate assemblages. Analysis of variance identified differences in environmental and biotic characteristics of the groups. These results combined with the results of canonical correspondence analysis indicated that patterns in riffle sample assemblage structure were highly correlated with a gradient in physical and chemical conditions associated with elevation. The results also suggested that flow regulation associated with large storage reservoirs has negative effects on the total number of taxa and density of macroinvertebrates below foothill dams. Analysis of the snag samples showed that, although elevation remained a significant variable, mean dominant substrate size, gradient, specific conductance, water temperature, percentage of the basin in agricultural land use, and percentage of the basin in combined agricultural and urban land uses were more important factors in explaining assemblage structure. Macroinvertebrate assemblages on snags may be useful in family level bioassessments of environmental conditions in valley floor habitats. In the Sierra Nevada and its foothills, the strong influence of elevation made it difficult to attribute differences in macroinvertebrate assemblage structure among sites to specific environmental conditions. Additional work is needed in the foothills and Sierra Nevada to better define macroinvertebrate assemblages and their relations to environmental variables.

Plant species invasions along the latitudinal gradient in the United States

USGS Publications Warehouse

Stohlgren, T.J.; Barnett, D.; Flather, C.; Kartesz, J.; Peterjohn, B.

2005-01-01

It has been long established that the richness of vascular plant species and many animal taxa decreases with increasing latitude, a pattern that very generally follows declines in actual and potential evapotranspiration, solar radiation, temperature, and thus, total productivity. Using county-level data on vascular plants from the United States (3000 counties in the conterminous 48 states), we used the Akaike Information Criterion (AIC) to evaluate competing models predicting native and nonnative plant species density (number of species per square kilometer in a county) from various combinations of biotic variables (e.g., native bird species density, vegetation carbon, normalized difference vegetation index), environmental/topographic variables (elevation, variation in elevation, the number of land cover classes in the county; radiation, mean precipitation, actual evapotranspiration, and potential evapotranspiration), and human variables (human population density, crop-land, and percentage of disturbed lands in a county). We found no evidence of a latitudinal gradient for the density of native plant species and a significant, slightly positive latitudinal gradient for the density of nonnative plant species. We found stronger evidence of a significant, positive productivity gradient (vegetation carbon) for the density of native plant species and nonnative plant species. We found much stronger significant relationships when biotic, environmental/topographic, and human variables were used to predict native plant species density and nonnative plant species density. Biotic variables generally had far greater influence in multivariate models than human or environmental/topographic variables. Later, we found that the best, single, positive predictor of the density of nonnative plant species in a county was the density of native plant species in a county. While further study is needed, it may be that, while humans facilitate the initial establishment invasions of nonnative plant species, the spread and subsequent distributions of nonnative species are controlled largely by biotic and environmental factors.

Modelling climate change and malaria transmission.

PubMed

Parham, Paul E; Michael, Edwin

2010-01-01

The impact of climate change on human health has received increasing attention in recent years, with potential impacts due to vector-borne diseases only now beginning to be understood. As the most severe vector-borne disease, with one million deaths globally in 2006, malaria is thought most likely to be affected by changes in climate variables due to the sensitivity of its transmission dynamics to environmental conditions. While considerable research has been carried out using statistical models to better assess the relationship between changes in environmental variables and malaria incidence, less progress has been made on developing process-based climate-driven mathematical models with greater explanatory power. Here, we develop a simple model of malaria transmission linked to climate which permits useful insights into the sensitivity of disease transmission to changes in rainfall and temperature variables. Both the impact of changes in the mean values of these key external variables and importantly temporal variation in these values are explored. We show that the development and analysis of such dynamic climate-driven transmission models will be crucial to understanding the rate at which P. falciparum and P. vivax may either infect, expand into or go extinct in populations as local environmental conditions change. Malaria becomes endemic in a population when the basic reproduction number R0 is greater than unity and we identify an optimum climate-driven transmission window for the disease, thus providing a useful indicator for determing how transmission risk may change as climate changes. Overall, our results indicate that considerable work is required to better understand ways in which global malaria incidence and distribution may alter with climate change. In particular, we show that the roles of seasonality, stochasticity and variability in environmental variables, as well as ultimately anthropogenic effects, require further study. The work presented here offers a theoretical framework upon which this future research may be developed.

Phenology Analysis of Forest Vegetation to Environmental Variables during - and Post-Monsoon Seasons in Western Himalayan Region of India

NASA Astrophysics Data System (ADS)

Khare, S.; Latifi, H.; Ghosh, K.

2016-06-01

To assess the phenological changes in Moist Deciduous Forest (MDF) of western Himalayan region of India, we carried out NDVI time series analysis from 2013 to 2015 using Landsat 8 OLI data. We used the vegetation index differencing method to calculate the change in NDVI (NDVIchange) during pre and post monsoon seasons and these changes were used to assess the phenological behaviour of MDF by taking the effect of a set of environmental variables into account. To understand the effect of environmental variables on change in phenology, we designed a linear regression analysis with sample-based NDVIchange values as the response variable and elevation aspect, and Land Surface Temperature (LST) as explanatory variables. The Landsat-8 derived phenology transition stages were validated by calculating the phenology variation from Nov 2008 to April 2009 using Landsat-7 which has the same spatial resolution as Landsat-8. The Landsat-7 derived NDVI trajectories were plotted in accordance with MODIS derived phenology stages (from Nov 2008 to April 2009) of MDF. Results indicate that the Landsat -8 derived NDVI trajectories describing the phenology variation of MDF during spring, monsoon autumn and winter seasons agreed closely with Landsat-7 and MODIS derived phenology transition from Nov 2008 to April 2009. Furthermore, statistical analysis showed statistically significant correlations (p < 0.05) amongst the environmental variables and the NDVIchange between full greenness and maximum frequency stage of Onset of Greenness (OG) activity.. The major change in NDVI was observed in medium (600 to 650 m) and maximum (650 to 750 m) elevation areas. The change in LST showed also to be highly influential. The results of this study can be used for large scale monitoring of difficult-to-reach mountainous forests, with additional implications in biodiversity assessment. By means of a sufficient amount of available cloud-free imagery, detailed phenological trends across mountainous forests could be explained.

Developing a spatial-statistical model and map of historical malaria prevalence in Botswana using a staged variable selection procedure

PubMed Central

Craig, Marlies H; Sharp, Brian L; Mabaso, Musawenkosi LH; Kleinschmidt, Immo

2007-01-01

Background Several malaria risk maps have been developed in recent years, many from the prevalence of infection data collated by the MARA (Mapping Malaria Risk in Africa) project, and using various environmental data sets as predictors. Variable selection is a major obstacle due to analytical problems caused by over-fitting, confounding and non-independence in the data. Testing and comparing every combination of explanatory variables in a Bayesian spatial framework remains unfeasible for most researchers. The aim of this study was to develop a malaria risk map using a systematic and practicable variable selection process for spatial analysis and mapping of historical malaria risk in Botswana. Results Of 50 potential explanatory variables from eight environmental data themes, 42 were significantly associated with malaria prevalence in univariate logistic regression and were ranked by the Akaike Information Criterion. Those correlated with higher-ranking relatives of the same environmental theme, were temporarily excluded. The remaining 14 candidates were ranked by selection frequency after running automated step-wise selection procedures on 1000 bootstrap samples drawn from the data. A non-spatial multiple-variable model was developed through step-wise inclusion in order of selection frequency. Previously excluded variables were then re-evaluated for inclusion, using further step-wise bootstrap procedures, resulting in the exclusion of another variable. Finally a Bayesian geo-statistical model using Markov Chain Monte Carlo simulation was fitted to the data, resulting in a final model of three predictor variables, namely summer rainfall, mean annual temperature and altitude. Each was independently and significantly associated with malaria prevalence after allowing for spatial correlation. This model was used to predict malaria prevalence at unobserved locations, producing a smooth risk map for the whole country. Conclusion We have produced a highly plausible and parsimonious model of historical malaria risk for Botswana from point-referenced data from a 1961/2 prevalence survey of malaria infection in 1–14 year old children. After starting with a list of 50 potential variables we ended with three highly plausible predictors, by applying a systematic and repeatable staged variable selection procedure that included a spatial analysis, which has application for other environmentally determined infectious diseases. All this was accomplished using general-purpose statistical software. PMID:17892584

Physiological Responses in a Variable Environment: Relationships between Metabolism, Hsp and Thermotolerance in an Intertidal-Subtidal Species

PubMed Central

Wang, Qing-lin; Dong, Shuang-lin

2011-01-01

Physiological responses to temperature reflect the evolutionary adaptations of organisms to their thermal environment and the capability of animals to tolerate thermal stress. Contrary to conventional metabolism theory, increasing environmental temperatures have been shown to reduce metabolic rate in rocky–eulittoral-fringe species inhabiting highly variable environments, possibly as a strategy for energy conservation. To study the physiological adaptations of an intertidal-subtidal species to the extreme and unpredictable heat stress of the intertidal zone, oxygen consumption rate and heat shock protein expression were quantified in the sea cucumber Apostichopus japonicus. Using simulate natural temperatures, the relationship between temperature, physiological performance (oxygen consumption and heat shock proteins) and thermotolerance were assessed. Depression of oxygen consumption rate and upregulation of heat shock protein genes (hsps) occurred in sequence when ambient temperature was increased from 24 to 30°C. Large-scale mortality of the sea cucumber occurred when temperatures rose beyond 30°C, suggesting that the upregulation of heat shock proteins and mortality are closely related to the depression of aerobic metabolism, a phenomenon that is in line with the concept of oxygen- and capacity-limited thermal tolerance (OCLTT). The physiologically-related thermotolerance of this sea cucumber should be an adaptation to its local environment. PMID:22022615

Aerospace Ceramic Materials: Thermal, Environmental Barrier Coatings and SiC/SiC Ceramic Matrix Composites for Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2018-01-01

Ceramic materials play increasingly important roles in aerospace applications because ceramics have unique properties, including high temperature capability, high stiffness and strengths, excellent oxidation and corrosion resistance. Ceramic materials also generally have lower densities as compared to metallic materials, making them excellent candidates for light-weight hot-section components of aircraft turbine engines, rocket exhaust nozzles, and thermal protection systems for space vehicles when they are being used for high-temperature and ultra-high temperature ceramics applications. Ceramic matrix composites (CMCs), including non-oxide and oxide CMCs, are also recently being incorporated in gas turbine engines for high pressure and high temperature section components and exhaust nozzles. However, the complexity and variability of aerospace ceramic processing methods, compositions and microstructures, the relatively low fracture toughness of the ceramic materials, still remain the challenging factors for ceramic component design, validation, life prediction, and thus broader applications. This ceramic material section paper presents an overview of aerospace ceramic materials and their characteristics. A particular emphasis has been placed on high technology level (TRL) enabling ceramic systems, that is, turbine engine thermal and environmental barrier coating systems and non-oxide type SiC/SiC CMCs. The current status and future trend of thermal and environmental barrier coatings and SiC/SiC CMC development and applications are described.

Annual growth patterns of baldcypress (Taxodium distichum) along salinity gradients

USGS Publications Warehouse

Thomas, Brenda L.; Doyle, Thomas W.; Krauss, Ken W.

2015-01-01

The effects of salinity on Taxodium distichum seedlings have been well documented, but few studies have examined mature trees in situ. We investigated the environmental drivers of T. distichum growth along a salinity gradient on the Waccamaw (South Carolina) and Savannah (Georgia) Rivers. On each river, T. distichum increment cores were collected from a healthy upstream site (Upper), a moderately degraded mid-reach site (Middle), and a highly degraded downstream site (Lower). Chronologies were successfully developed for Waccamaw Upper and Middle, and Savannah Middle. Correlations between standardized chronologies and environmental variables showed significant relationships between T. distichum growth and early growing season precipitation, temperature, and Palmer Drought Severity Index (PDSI). Savannah Middle chronology correlated most strongly with August river salinity levels. Both lower sites experienced suppression/release events likely in response to local anthropogenic impacts rather than regional environmental variables. The factors that affect T. distichum growth, including salinity, are strongly synergistic. As sea-level rise pushes the freshwater/saltwater interface inland, salinity becomes more limiting to T. distichum growth in tidal freshwater swamps; however, salinity impacts are exacerbated by locally imposed environmental modifications.

Population Structure and Gene Flow of the Yellow Anaconda (Eunectes notaeus) in Northern Argentina

PubMed Central

McCartney-Melstad, Evan; Waller, Tomás; Micucci, Patricio A.; Barros, Mariano; Draque, Juan; Amato, George; Mendez, Martin

2012-01-01

Yellow anacondas (Eunectes notaeus) are large, semiaquatic boid snakes found in wetland systems in South America. These snakes are commercially harvested under a sustainable management plan in Argentina, so information regarding population structuring can be helpful for determination of management units. We evaluated genetic structure and migration using partial sequences from the mitochondrial control region and mitochondrial genes cyt-b and ND4 for 183 samples collected within northern Argentina. A group of landscape features and environmental variables including several treatments of temperature and precipitation were explored as potential drivers of observed genetic patterns. We found significant population structure between most putative population comparisons and bidirectional but asymmetric migration in several cases. The configuration of rivers and wetlands was found to be significantly associated with yellow anaconda population structure (IBD), and important for gene flow, although genetic distances were not significantly correlated with the environmental variables used here. More in-depth analyses of environmental data may be needed to fully understand the importance of environmental conditions on population structure and migration. These analyses indicate that our putative populations are demographically distinct and should be treated as such in Argentina's management plan for the harvesting of yellow anacondas. PMID:22675425

Environmental conditions and Puumala virus transmission in Belgium

PubMed Central

Linard, Catherine; Tersago, Katrien; Leirs, Herwig; Lambin, Eric F

2007-01-01

Background Non-vector-borne zoonoses such as Puumala hantavirus (PUUV) can be transmitted directly, by physical contact between infected and susceptible hosts, or indirectly, with the environment as an intermediate. The objective of this study is to better understand the causal link between environmental features and PUUV prevalence in bank vole population in Belgium, and hence with transmission risk to humans. Our hypothesis was that environmental conditions controlling the direct and indirect transmission paths differ, such that the risk of transmission to humans is not only determined by host abundance. We explored the relationship between, on one hand, environmental variables and, on the other hand, host abundance, PUUV prevalence in the host, and human cases of nephropathia epidemica (NE). Statistical analyses were carried out on 17 field sites situated in Belgian broadleaf forests. Results Linear regressions showed that landscape attributes, particularly landscape configuration, influence the abundance of hosts in broadleaf forests. Based on logistic regressions, we show that PUUV prevalence among bank voles is more linked to variables favouring the survival of the virus in the environment, and thus the indirect transmission: low winter temperatures are strongly linked to prevalence among bank voles, and high soil moisture is linked to the number of NE cases among humans. The transmission risk to humans therefore depends on the efficiency of the indirect transmission path. Human risk behaviours, such as the propensity for people to go in forest areas that best support the virus, also influence the number of human cases. Conclusion The transmission risk to humans of non-vector-borne zoonoses such as PUUV depends on a combination of various environmental factors. To understand the complex causal pathways between the environment and disease risk, one should distinguish between environmental factors related to the abundance of hosts such as land-surface attributes, landscape configuration, and climate – i.e., host ecology, – and environmental factors related to PUUV prevalence, mainly winter temperatures and soil moisture – i.e., virus ecology. Beyond a threshold abundance of hosts, environmental factors favouring the indirect transmission path (soil and climate) can better predict the number of NE cases among humans than factors influencing the abundance of hosts. PMID:18078526

Structure and stability of pyrophyllite edge surfaces: Effect of temperature and water chemical potential

NASA Astrophysics Data System (ADS)

Kwon, Kideok D.; Newton, Aric G.

2016-10-01

The surfaces of clay minerals, which are abundant in atmospheric mineral dust, serve as an important medium to catalyze ice nucleation. The lateral edge surface of 2:1 clay minerals is postulated to be a potential site for ice nucleation. However, experimental investigations of the edge surface structure itself have been limited compared to the basal planes of clay minerals. Density functional theory (DFT) computational studies have provided insights into the pyrophyllite edge surface. Pyrophyllite is an ideal surrogate mineral for the edge surfaces of 2:1 clay minerals as it possesses no or little structural charge. Of the two most-common hydrated edge surfaces, the AC edge, (1 1 0) surface in the monoclinic polytype notation, is predicted to be more stable than the B edge, (0 1 0) surface. These stabilities, however, were determined based on the total energies calculated at 0 K and did not consider environmental effects such as temperature and humidity. In this study, atomistic thermodynamics based on periodic DFT electronic calculations was applied to examine the effects of environmental variables on the structure and thermodynamic stability of the common edge surfaces in equilibrium with bulk pyrophyllite and water vapor. We demonstrate that the temperature-dependent vibrational energy of sorbed water molecules at the edge surface is a significant component of the surface free energy and cannot be neglected when determining the surface stability of pyrophyllite. The surface free energies were calculated as a function of temperature from 240 to 600 K and water chemical potential corresponding to conditions from ultrahigh vacuum to the saturation vapor pressure of water. We show that at lower water chemical potentials (dry conditions), the AC and B edge surfaces possessed similar stabilities; at higher chemical potentials (humid conditions) the AC edge surface was more stable than the B edge surface. At high temperatures, both surfaces showed similar stabilities regardless of the water chemical potential. The equilibrium morphology of pyrophyllite crystals is also expected to be dependent on these two environmental variables. Surface defects may impact the surface reactivity. We discuss the thermodynamic stability of a possible Si cation vacancy defect which provides additional hydroxyl group on the surface.

Soil Temperature Variability in Complex Terrain measured using Distributed a Fiber-Optic Distributed Temperature Sensing

NASA Astrophysics Data System (ADS)

Seyfried, M. S.; Link, T. E.

2013-12-01

Soil temperature (Ts) exerts critical environmental controls on hydrologic and biogeochemical processes. Rates of carbon cycling, mineral weathering, infiltration and snow melt are all influenced by Ts. Although broadly reflective of the climate, Ts is sensitive to local variations in cover (vegetative, litter, snow), topography (slope, aspect, position), and soil properties (texture, water content), resulting in a spatially and temporally complex distribution of Ts across the landscape. Understanding and quantifying the processes controlled by Ts requires an understanding of that distribution. Relatively few spatially distributed field Ts data exist, partly because traditional Ts data are point measurements. A relatively new technology, fiber optic distributed temperature system (FO-DTS), has the potential to provide such data but has not been rigorously evaluated in the context of remote, long term field research. We installed FO-DTS in a small experimental watershed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of SW Idaho. The watershed is characterized by complex terrain and a seasonal snow cover. Our objectives are to: (i) evaluate the applicability of fiber optic DTS to remote field environments and (ii) to describe the spatial and temporal variability of soil temperature in complex terrain influenced by a variable snow cover. We installed fiber optic cable at a depth of 10 cm in contrasting snow accumulation and topographic environments and monitored temperature along 750 m with DTS. We found that the DTS can provide accurate Ts data (+/- .4°C) that resolves Ts changes of about 0.03°C at a spatial scale of 1 m with occasional calibration under conditions with an ambient temperature range of 50°C. We note that there are site-specific limitations related cable installation and destruction by local fauna. The FO-DTS provide unique insight into the spatial and temporal variability of Ts in a landscape. We found strong seasonal trends in Ts variability controlled by snow cover and solar radiation as modified by topography. During periods of spatially continuous snow cover Ts was practically homogeneous throughout. In the absence of snow cover, Ts is highly variable, with most of the variability attributable to different topographic units defined by slope and aspect. During transition periods when snow melts out, Ts is highly variable within the watershed and within topographic units. The importance of accounting for these relatively small scale effects is underscored by the fact that the overall range of Ts in study area 600 m long is similar to that of the much large RCEW with 900 m elevation gradient.

Identifying Environmental Risk Factors of Cholera in a Coastal Area with Geospatial Technologies

PubMed Central

Xu, Min; Cao, Chunxiang; Wang, Duochun; Kan, Biao

2014-01-01

Satellites contribute significantly to environmental quality and public health. Environmental factors are important indicators for the prediction of disease outbreaks. This study reveals the environmental factors associated with cholera in Zhejiang, a coastal province of China, using both Remote Sensing (RS) and Geographic information System (GIS). The analysis validated the correlation between the indirect satellite measurements of sea surface temperature (SST), sea surface height (SSH) and ocean chlorophyll concentration (OCC) and the local cholera magnitude based on a ten-year monthly data from the year 1999 to 2008. Cholera magnitude has been strongly affected by the concurrent variables of SST and SSH, while OCC has a one-month time lag effect. A cholera prediction model has been established based on the sea environmental factors. The results of hot spot analysis showed the local cholera magnitude in counties significantly associated with the estuaries and rivers. PMID:25551518

Identifying environmental risk factors of cholera in a coastal area with geospatial technologies.

PubMed

Xu, Min; Cao, Chunxiang; Wang, Duochun; Kan, Biao

2014-12-29

Satellites contribute significantly to environmental quality and public health. Environmental factors are important indicators for the prediction of disease outbreaks. This study reveals the environmental factors associated with cholera in Zhejiang, a coastal province of China, using both Remote Sensing (RS) and Geographic information System (GIS). The analysis validated the correlation between the indirect satellite measurements of sea surface temperature (SST), sea surface height (SSH) and ocean chlorophyll concentration (OCC) and the local cholera magnitude based on a ten-year monthly data from the year 1999 to 2008. Cholera magnitude has been strongly affected by the concurrent variables of SST and SSH, while OCC has a one-month time lag effect. A cholera prediction model has been established based on the sea environmental factors. The results of hot spot analysis showed the local cholera magnitude in counties significantly associated with the estuaries and rivers.

Estimating switchgrass productivity in the Great Plains using satellite vegetation index and site environmental variables

USGS Publications Warehouse

Gu, Yingxin; Wylie, Bruce K.; Howard, Daniel M.

2015-01-01

Switchgrass is being evaluated as a potential feedstock source for cellulosic biofuels and is being cultivated in several regions of the United States. The recent availability of switchgrass land cover maps derived from the National Agricultural Statistics Service cropland data layer for the conterminous United States provides an opportunity to assess the environmental conditions of switchgrass over large areas and across different geographic locations. The main goal of this study is to develop a data-driven multiple regression switchgrass productivity model and identify the optimal climate and environment conditions for the highly productive switchgrass in the Great Plains (GP). Environmental and climate variables used in the study include elevation, soil organic carbon, available water capacity, climate, and seasonal weather. Satellite-derived growing season averaged Normalized Difference Vegetation Index (GSN) was used as a proxy for switchgrass productivity. Multiple regression analyses indicate that there are strong correlations between site environmental variables and switchgrass productivity (r = 0.95). Sufficient precipitation and suitable temperature during the growing season (i.e., not too hot or too cold) are favorable for switchgrass growth. Elevation and soil characteristics (e.g., soil available water capacity) are also an important factor impacting switchgrass productivity. An anticipated switchgrass biomass productivity map for the entire GP based on site environmental and climate conditions and switchgrass productivity model was generated. Highly productive switchgrass areas are mainly located in the eastern part of the GP. Results from this study can help land managers and biofuel plant investors better understand the general environmental and climate conditions influencing switchgrass growth and make optimal land use decisions regarding switchgrass development in the GP.

Use of Wearable Sensors and Biometric Variables in an Artificial Pancreas System

PubMed Central

Turksoy, Kamuran; Monforti, Colleen; Park, Minsun; Griffith, Garett; Quinn, Laurie; Cinar, Ali

2017-01-01

An artificial pancreas (AP) computes the optimal insulin dose to be infused through an insulin pump in people with Type 1 Diabetes (T1D) based on information received from a continuous glucose monitoring (CGM) sensor. It has been recognized that exercise is a major challenge in the development of an AP system. The use of biometric physiological variables in an AP system may be beneficial for prevention of exercise-induced challenges and better glucose regulation. The goal of the present study is to find a correlation between biometric variables such as heart rate (HR), heat flux (HF), skin temperature (ST), near-body temperature (NBT), galvanic skin response (GSR), and energy expenditure (EE), 2D acceleration-mean of absolute difference (MAD) and changes in glucose concentrations during exercise via partial least squares (PLS) regression and variable importance in projection (VIP) in order to determine which variables would be most useful to include in a future artificial pancreas. PLS and VIP analyses were performed on data sets that included seven different types of exercises. Data were collected from 26 clinical experiments. Clinical results indicate ST to be the most consistently important (important for six out of seven tested exercises) variable over all different exercises tested. EE and HR are also found to be important variables over several types of exercise. We also found that the importance of GSR and NBT observed in our experiments might be related to stress and the effect of changes in environmental temperature on glucose concentrations. The use of the biometric measurements in an AP system may provide better control of glucose concentration. PMID:28272368

A respiratory alert model for the Shenandoah Valley, Virginia, USA

NASA Astrophysics Data System (ADS)

Hondula, David M.; Davis, Robert E.; Knight, David B.; Sitka, Luke J.; Enfield, Kyle; Gawtry, Stephen B.; Stenger, Phillip J.; Deaton, Michael L.; Normile, Caroline P.; Lee, Temple R.

2013-01-01

Respiratory morbidity (particularly COPD and asthma) can be influenced by short-term weather fluctuations that affect air quality and lung function. We developed a model to evaluate meteorological conditions associated with respiratory hospital admissions in the Shenandoah Valley of Virginia, USA. We generated ensembles of classification trees based on six years of respiratory-related hospital admissions (64,620 cases) and a suite of 83 potential environmental predictor variables. As our goal was to identify short-term weather linkages to high admission periods, the dependent variable was formulated as a binary classification of five-day moving average respiratory admission departures from the seasonal mean value. Accounting for seasonality removed the long-term apparent inverse relationship between temperature and admissions. We generated eight total models specific to the northern and southern portions of the valley for each season. All eight models demonstrate predictive skill (mean odds ratio = 3.635) when evaluated using a randomization procedure. The predictor variables selected by the ensembling algorithm vary across models, and both meteorological and air quality variables are included. In general, the models indicate complex linkages between respiratory health and environmental conditions that may be difficult to identify using more traditional approaches.

Seasonal and interannual variability of atmospheric heat sources and moisture sinks as determined from NCEP/NCAR ranalysis. Part I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yanai, Michio; Tomita, Tomohiko

1997-11-01

In this paper, an analysis of the heat and moisture budgets of the troposphere is revised and extended. The analysis is based on the National Centers for Environmental Prediction (NCEP) and National Center for Atmospheric Research (NCAR) reanalysis from 1980 to 1994. The seasonal and interannual variability of heat sources and sinks and the nature of heating over various geographical locations is examined in detail. Results presented include global distributions of the 15-year mean of the vertically integrated heat source and moisture sink and the outgoing longwave radiation flux for northern winter and northern summer. A time series of monthlymore » mean anomalies of the apparent heat source, the apparent moisture sink, outgoing longwave radiation, sea surface temperature, and divergence at wind fields of 850 hPa and 200 hPa are presented for the equatorial Indian Ocean, the equatorial eastern Pacific Ocean, western Tibet, and eastern Tibet. In the equatorial Indian Ocean, short period oscillation is superimposed upon longer periods. Over the eastern Pacific, a longer periodicity is dominant and the variability of the heat source is very well correlated with similar variations of outgoing longwave radiation, sea surface temperature, and horizontal divergence. The high correlation with these variables suggests that anomalous heating is accompanied by intensified convective activity favored by warmer sea surface temperature. 13 refs., 5 figs.« less

Using motion-sensor camera technology to infer seasonal activity and thermal niche of the desert tortoise (Gopherus agassizii).

PubMed

Agha, Mickey; Augustine, Benjamin; Lovich, Jeffrey E; Delaney, David; Sinervo, Barry; Murphy, Mason O; Ennen, Joshua R; Briggs, Jessica R; Cooper, Robert; Price, Steven J

2015-01-01

Understanding the relationships between environmental variables and wildlife activity is an important part of effective management. The desert tortoise (Gopherus agassizii), an imperiled species of arid environments in the southwest US, may have increasingly restricted windows for activity due to current warming trends. In summer 2013, we deployed 48 motion sensor cameras at the entrances of tortoise burrows to investigate the effects of temperature, sex, and day of the year on the activity of desert tortoises. Using generalized estimating equations, we found that the relative probability of activity was associated with temperature (linear and quadratic), sex, and day of the year. Sex effects showed that male tortoises are generally more active than female tortoises. Temperature had a quadratic effect, indicating that tortoise activity was heightened at a range of temperatures. In addition, we found significant support for interactions between sex and day of the year, and sex and temperature as predictors of the probability of activity. Using our models, we were able to estimate air temperatures and times (days and hours) that were associated with maximum activity during the study. Because tortoise activity is constrained by environmental conditions such as temperature, it is increasingly vital to conduct studies on how tortoises vary their activity throughout the Sonoran Desert to better understand the effects of a changing climate. Copyright © 2015 Elsevier Ltd. All rights reserved.

Using motion-sensor camera technology to infer seasonal activity and thermal niche of the desert tortoise (Gopherus agassizii)

USGS Publications Warehouse

Agha, Mickey; Augustine, Benjamin; Lovich, Jeffrey E.; Delaney, David F.; Sinervo, Barry; Murphy, Mason O.; Ennen, Joshua R.; Briggs, Jessica R.; Cooper, Robert J.; Price, Steven J.

2015-01-01

Understanding the relationships between environmental variables and wildlife activity is an important part of effective management. The desert tortoise (Gopherus agassizii), an imperiled species of arid environments in the southwest US, may have increasingly restricted windows for activity due to current warming trends. In summer 2013, we deployed 48 motion sensor cameras at the entrances of tortoise burrows to investigate the effects of temperature, sex, and day of the year on the activity of desert tortoises. Using generalized estimating equations, we found that the relative probability of activity was associated with temperature (linear and quadratic), sex, and day of the year. Sex effects showed that male tortoises are generally more active than female tortoises. Temperature had a quadratic effect, indicating that tortoise activity was heightened at a range of temperatures. In addition, we found significant support for interactions between sex and day of the year, and sex and temperature as predictors of the probability of activity. Using our models, we were able to estimate air temperatures and times (days and hours) that were associated with maximum activity during the study. Because tortoise activity is constrained by environmental conditions such as temperature, it is increasingly vital to conduct studies on how tortoises vary their activity throughout the Sonoran Desert to better understand the effects of a changing climate.

Temporally increasing spatial synchrony of North American temperature and bird populations

NASA Astrophysics Data System (ADS)

Koenig, Walter D.; Liebhold, Andrew M.

2016-06-01

The ecological impacts of modern global climate change are detectable in a wide variety of phenomena, ranging from shifts in species ranges to changes in community composition and human disease dynamics. So far, however, little attention has been given to temporal changes in spatial synchrony--the coincident change in abundance or value across the landscape--despite the importance of environmental synchrony as a driver of population trends and the central role of environmental variability in population rescue and extinction. Here we demonstrate that across North America, spatial synchrony of a significant proportion of 49 widespread North American wintering bird species has increased over the past 50 years--the period encompassing particularly intense anthropogenic effects in climate--paralleling significant increases in spatial synchrony of mean maximum air temperature. These results suggest the potential for increased spatial synchrony in environmental factors to be affecting a wide range of ecological phenomena. These effects are likely to vary, but for North American wildlife species, increased spatial synchrony driven by environmental factors may be the basis for a previously unrecognized threat to their long-term persistence in the form of more synchronized population dynamics reducing the potential for demographic rescue among interacting subpopulations.

Influences of temperature and environmental variables on the distribution of bull trout within streams at the southern margin of its range

Treesearch

J. Dunham; B. Rieman; G. Chandler

2003-01-01

The bull trout Salvelinus confluentus is believed to be among the most thermally sensitive species in coldwater habitats in western North America. We conducted a comprehensive field assessment of thermal habitat associations throughout the southern margin of the species' range. We developed models of thermal habitat associations using two data sets representing a...

Environmental Benefits of Restoring Sediment Continuity to the Kansas River

DTIC Science & Technology

2016-06-01

CHL CHETN-XIV-50 June 2016 12 Bonner, T. H., and G. R. Wilde. 2002. Effects of turbidity on prey consumption by prairie stream fishes ...increased turbidity can also impact heat distribution and cause increased temperature variability. High biological oxygen demand related to algae...populations can drastically reduce dissolved oxygen concentrations, leading to an increased risk of fish kills (Miranda et al. 2001). Fish species

Life Prediction Issues in Thermal/Environmental Barrier Coatings in Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Shah, Ashwin R.; Brewer, David N.; Murthy, Pappu L. N.

2001-01-01

Issues and design requirements for the environmental barrier coating (EBC)/thermal barrier coating (TBC) life that are general and those specific to the NASA Ultra-Efficient Engine Technology (UEET) development program have been described. The current state and trend of the research, methods in vogue related to the failure analysis, and long-term behavior and life prediction of EBCITBC systems are reported. Also, the perceived failure mechanisms, variables, and related uncertainties governing the EBCITBC system life are summarized. A combined heat transfer and structural analysis approach based on the oxidation kinetics using the Arrhenius theory is proposed to develop a life prediction model for the EBC/TBC systems. Stochastic process-based reliability approach that includes the physical variables such as gas pressure, temperature, velocity, moisture content, crack density, oxygen content, etc., is suggested. Benefits of the reliability-based approach are also discussed in the report.

Disparities in Ammonia, Temperature, Humidity, and Airborne Particulate Matter between the Micro-and Macroenvironments of Mice in Individually Ventilated Caging

PubMed Central

Rosenbaum, Matthew D; VandeWoude, Susan; Volckens, John; Johnson, Thomas E

2010-01-01

Animal room environmental parameters typically are monitored with the assumption that the environment within the cage closely mirrors the room environment. This study evaluated that premise by examining macro- (room) and microenvironmental (cage) parameters in individually ventilated cages housing mice with variable amounts of bedding over a period of 17 d without cage changes. Intracage ammonia levels remained within recommended human guidelines but were higher than room levels, confirming that microisolation caging is efficient at preventing ammonia generated from animal waste from escaping into the room. Humidity and temperature within cages were consistently higher than room levels. Particles in the room predominantly consisted of fine particles (diameter less than 2.5 µm), presumably from the ambient atmosphere; some of these particles were found in the cage microenvironment. In addition, mouse activity within cages produced larger particles, and these particles contributed to substantially higher aerosol mass concentrations within the cage. These findings demonstrate that, although cage and room environmental parameters differ, knowledge of room environmental conditions can be used to predict certain conditions within the cage. This association is relevant in that typical animal care standard operating procedures rely on room measurements, not intracage measurements, which arguably are more important for assessing animal welfare. Further, location and ambient climate can influence particle concentrations in the room, and consequently within the animal cage, suggesting local weather patterns and air quality may account for variability among studies conducted at sites that are geographically divergent. PMID:20353692

Bird Communities and Environmental Correlates in Southern Oregon and Northern California, USA.

PubMed

Stephens, Jaime L; Dinger, Eric C; Alexander, John D; Mohren, Sean R; Ralph, C John; Sarr, Daniel A

2016-01-01

We examined avian community ecology in the Klamath Ecoregion and determined that individual bird species co-exist spatially to form 29 statistically distinguishable bird groups. We identified climate, geography, and vegetation metrics that are correlated with these 29 bird groups at three scales: Klamath Ecoregion, vegetation formation (agriculture, conifer, mixed conifer/hardwood, shrubland), and National Park Service unit. Two climate variables (breeding season mean temperature and temperature range) and one geography variable (elevation) were correlated at all scales, suggesting that for some vegetation formations and park units there is sufficient variation in climate and geography to be an important driver of bird communities, a level of variation we expected only at the broader scale. We found vegetation to be important at all scales, with coarse metrics (environmental site potential and existing vegetation formation) meaningful across all scales and structural vegetation patterns (e.g. succession, disturbance) important only at the scale of vegetation formation or park unit. Additionally, we examined how well six National Park Service units represent bird communities in the broader Klamath Ecoregion. Park units are inclusive of most bird communities with the exception of the oak woodland community; mature conifer forests are well represented, primarily associated with conifer canopy and lacking multi-layered structure. Identifying environmental factors that shape bird communities at three scales within this region is important; such insights can inform local and regional land management decisions necessary to ensure bird conservation in this globally significant region.

Bird Communities and Environmental Correlates in Southern Oregon and Northern California, USA

PubMed Central

Dinger, Eric C.; Alexander, John D.; Mohren, Sean R.; Ralph, C. John; Sarr, Daniel A.

2016-01-01

We examined avian community ecology in the Klamath Ecoregion and determined that individual bird species co-exist spatially to form 29 statistically distinguishable bird groups. We identified climate, geography, and vegetation metrics that are correlated with these 29 bird groups at three scales: Klamath Ecoregion, vegetation formation (agriculture, conifer, mixed conifer/hardwood, shrubland), and National Park Service unit. Two climate variables (breeding season mean temperature and temperature range) and one geography variable (elevation) were correlated at all scales, suggesting that for some vegetation formations and park units there is sufficient variation in climate and geography to be an important driver of bird communities, a level of variation we expected only at the broader scale. We found vegetation to be important at all scales, with coarse metrics (environmental site potential and existing vegetation formation) meaningful across all scales and structural vegetation patterns (e.g. succession, disturbance) important only at the scale of vegetation formation or park unit. Additionally, we examined how well six National Park Service units represent bird communities in the broader Klamath Ecoregion. Park units are inclusive of most bird communities with the exception of the oak woodland community; mature conifer forests are well represented, primarily associated with conifer canopy and lacking multi-layered structure. Identifying environmental factors that shape bird communities at three scales within this region is important; such insights can inform local and regional land management decisions necessary to ensure bird conservation in this globally significant region. PMID:27732625

Intraspecific scaling in frog calls: the interplay of temperature, body size and metabolic condition.

PubMed

Ziegler, Lucia; Arim, Matías; Bozinovic, Francisco

2016-07-01

Understanding physiological and environmental determinants of strategies of reproductive allocation is a pivotal aim in biology. Because of their high metabolic cost, properties of sexual acoustic signals may correlate with body size, temperature, and an individual's energetic state. A quantitative theory of acoustic communication, based on the metabolic scaling with temperature and mass, was recently proposed, adding to the well-reported empirical patterns. It provides quantitative predictions for frequencies, call rate, and durations. Here, we analysed the mass, temperature, and body condition scaling of spectral and temporal attributes of the advertisement call of the treefrog Hypsiboas pulchellus. Mass dependence of call frequency followed metabolic expectations (f~M (-0.25), where f is frequency and M is mass) although non-metabolic allometry could also account for the observed pattern. Temporal variables scaled inversely with mass contradicting metabolic expectations (d~M (0.25), where d is duration), supporting instead empirical patterns reported to date. Temperature was positively associated with call rate and negatively with temporal variables, which is congruent with metabolic predictions. We found no significant association between temperature and frequencies, adding to the bulk of empirical evidence. Finally, a result of particular relevance was that body condition consistently determined call characteristics, in interaction with temperature or mass. Our intraspecific study highlights that even if proximate determinants of call variability are rather well understood, the mechanisms through which they operate are proving to be more complex than previously thought. The determinants of call characteristics emerge as a key topic of research in behavioural and physiological biology, with several clear points under debate which need to be analysed on theoretical and empirical grounds.

Temporal and spatial variation in temperature experienced by macrofauna at Main Endeavour hydrothermal vent field

NASA Astrophysics Data System (ADS)

Lee, Raymond W.; Robert, Katleen; Matabos, Marjolaine; Bates, Amanda E.; Juniper, S. Kim

2015-12-01

A significant focus of hydrothermal vent ecological studies has been to understand how species cope with various stressors through physiological tolerance and biochemical resistance. Yet, the environmental conditions experienced by vent species have not been well characterized. This objective requires continuous observations over time intervals that can capture environmental variability at scales that are relevant to animals. We used autonomous temperature logger arrays (four roughly parallel linear arrays of 12 loggers spaced every 10-12 cm) to study spatial and temporal variations in the thermal regime experienced by hydrothermal vent macrofauna at a diffuse flow vent. Hourly temperatures were recorded over eight months from 2010 to 2011 at Grotto vent in the Main Endeavour vent field on the Juan de Fuca Ridge, a focus area of the Ocean Networks Canada cabled observatory. The conspicuous animal assemblages in video footage contained Ridgeia piscesae tubeworms, gastropods (primarily Lepetodrilus fucensis), and polychaetes (polynoid scaleworms and the palm worm Paralvinella palmiformis). Two dimensional spatial gradients in temperature were generally stable over the deployment period. The average temperature recorded by all arrays, and in some individual loggers, revealed distinctive fluctuations in temperature that often corresponded with the tidal cycle. We postulate that this may be related to changes in bottom currents or fluctuations in vent discharge. A marked transient temperature increase lasting over a period of days was observed in April 2011. While the distributions and behavior of Juan de Fuca Ridge vent invertebrates may be partially constrained by environmental temperature and temperature tolerance, except for the one transient high-temperature event, observed fluid temperatures were generally similar to the thermal preferences for some species, and typically well below lethal temperatures for all species. Average temperatures of the four arrays ranged from 4.1 to 11.0 °C during the deployment, indicating that on an hourly timescale the temperature conditions in this tubeworm community were fairly moderate and stable. The generality of these findings and behavioral responses of vent organisms to predictable rhythmicity and non-periodic temperature shifts are areas for further investigation.

Delineating recurrent fish spawning habitats in the North Sea

NASA Astrophysics Data System (ADS)

Lelièvre, S.; Vaz, S.; Martin, C. S.; Loots, C.

2014-08-01

The functional value of spawning habitats makes them critically important for the completion of fish life cycles and spawning grounds are now considered to be “essential habitats”. Inter-annual fluctuations in spawning ground distributions of dab (Limanda Limanda), plaice (Pleuronectes platessa), cod (Gadus morhua) and whiting (Merlangius merlangus) were investigated in the southern North Sea and eastern English Channel, from 2006 to 2009. The preferential spawning habitats of these species were modelled using generalised linear models, with egg distribution being used as proxy of spawners' location. Egg spatial and temporal distributions were explored based on six environmental variables: sea surface temperature and salinity, chlorophyll a concentration, depth, bedstress and seabed sediment types. In most cases, egg density was found to be strongly related to these environmental variables. Egg densities were positively correlated with shallow to intermediate depths having low temperature and relatively high salinity. Habitat models were used to map annual, i.e. 2006 to 2009, winter spatial distributions of eggs, for each species separately. Then, annual maps were combined to explore the spatial variability of each species' spawning grounds, and define recurrent, occasional, rare and unfavourable spawning areas. The recurrent spawning grounds of all four species were located in the south-eastern part of the study area, mainly along the Dutch and German coasts. This study contributes knowledge necessary to the spatial management of fishery resources in the area, and may also be used to identify marine areas with particular habitat features that need to be preserved.

Utility of High Temporal Resolution Observations for Heat Health Event Characterization

NASA Astrophysics Data System (ADS)

Palecki, M. A.

2017-12-01

Many heat health watch systems produce a binary on/off warning when conditions are predicted to exceed a given threshold during a day. Days with warnings and their mortality/morbidity statistics are analyzed relative to days not warned to determine the impacts of the event on human health, the effectiveness of warnings, and other statistics. The climate analyses of the heat waves or extreme temperature events are often performed with hourly or daily observations of air temperature, humidity, and other measured or derived variables, especially the maxima and minima of these data. However, since the beginning of the century, 5-minute observations are readily available for many weather and climate stations in the United States. NOAA National Centers for Environmental Information (NCEI) has been collecting 5-minute observations from the NOAA Automated Surface Observing System (ASOS) stations since 2000, and from the U.S. Climate Reference Network (USCRN) stations since 2005. This presentation will demonstrate the efficacy of utilizing 5-minute environmental observations to characterize heat waves by counting the length of time conditions exceed extreme thresholds based on individual and multiple variables and on derived variables such as the heat index. The length and depth of recovery periods between daytime heating periods will also be examined. The length of time under extreme conditions will influence health outcomes for those directly exposed. Longer periods of dangerous conditions also could increase the chances for poor health outcomes for those only exposed intermittently through cumulative impacts.

Environmental Variables Explain Genetic Structure in a Beetle-Associated Nematode

PubMed Central

McGaughran, Angela; Morgan, Katy; Sommer, Ralf J.

2014-01-01

The distribution of a species is a complex expression of its ecological and evolutionary history and integrating population genetic, environmental, and ecological data can provide new insights into the effects of the environment on the population structure of species. Previous work demonstrated strong patterns of genetic differentiation in natural populations of the hermaphroditic nematode Pristionchus pacificus in its La Réunion Island habitat, but gave no clear understanding of the role of the environment in structuring this variation. Here, we present what is to our knowledge the first study to statistically evaluate the role of the environment in shaping the structure and distribution of nematode populations. We test the hypothesis that genetic structure in P. pacificus is influenced by environmental variables, by combining population genetic analyses of microsatellite data from 18 populations and 370 strains, with multivariate statistics on environmental data, and species distribution modelling. We assess and quantify the relative importance of environmental factors (geographic distance, altitude, temperature, precipitation, and beetle host) on genetic variation among populations. Despite the fact that geographic populations of P. pacificus comprise vast genetic diversity sourced from multiple ancestral lineages, we find strong evidence for local associations between environment and genetic variation. Further, we show that significantly more genetic variation in P. pacificus populations is explained by environmental variation than by geographic distances. This supports a strong role for environmental heterogeneity vs. genetic drift in the divergence of populations, which we suggest may be influenced by adaptive forces. PMID:24498073

Large Scale Variability of Phytoplankton Blooms in the Arctic and Peripheral Seas: Relationships with Sea Ice, Temperature, Clouds, and Wind

NASA Technical Reports Server (NTRS)

Comiso, Josefino C.; Cota, Glenn F.

2004-01-01

Spatially detailed satellite data of mean color, sea ice concentration, surface temperature, clouds, and wind have been analyzed to quantify and study the large scale regional and temporal variability of phytoplankton blooms in the Arctic and peripheral seas from 1998 to 2002. In the Arctic basin, phytoplankton chlorophyll displays a large symmetry with the Eastern Arctic having about fivefold higher concentrations than those of the Western Arctic. Large monthly and yearly variability is also observed in the peripheral seas with the largest blooms occurring in the Bering Sea, Sea of Okhotsk, and the Barents Sea during spring. There is large interannual and seasonal variability in biomass with average chlorophyll concentrations in 2002 and 2001 being higher than earlier years in spring and summer. The seasonality in the latitudinal distribution of blooms is also very different such that the North Atlantic is usually most expansive in spring while the North Pacific is more extensive in autumn. Environmental factors that influence phytoplankton growth were examined, and results show relatively high negative correlation with sea ice retreat and strong positive correlation with temperature in early spring. Plankton growth, as indicated by biomass accumulation, in the Arctic and subarctic increases up to a threshold surface temperature of about 276-277 degree K (3-4 degree C) beyond which the concentrations start to decrease suggesting an optimal temperature or nutrient depletion. The correlation with clouds is significant in some areas but negligible in other areas, while the correlations with wind speed and its components are generally weak. The effects of clouds and winds are less predictable with weekly climatologies because of unknown effects of averaging variable and intermittent physical forcing (e.g. over storm event scales with mixing and upwelling of nutrients) and the time scales of acclimation by the phytoplankton.

Elevated temperature is more effective than elevated [CO2 ] in exposing genotypic variation in Telopea speciosissima growth plasticity: implications for woody plant populations under climate change.

PubMed

Huang, Guomin; Rymer, Paul D; Duan, Honglang; Smith, Renee A; Tissue, David T

2015-10-01

Intraspecific variation in phenotypic plasticity is a critical determinant of plant species capacity to cope with climate change. A long-standing hypothesis states that greater levels of environmental variability will select for genotypes with greater phenotypic plasticity. However, few studies have examined how genotypes of woody species originating from contrasting environments respond to multiple climate change factors. Here, we investigated the main and interactive effects of elevated [CO2 ] (CE ) and elevated temperature (TE ) on growth and physiology of Coastal (warmer, less variable temperature environment) and Upland (cooler, more variable temperature environment) genotypes of an Australian woody species Telopea speciosissima. Both genotypes were positively responsive to CE (35% and 29% increase in whole-plant dry mass and leaf area, respectively), but only the Coastal genotype exhibited positive growth responses to TE . We found that the Coastal genotype exhibited greater growth response to TE (47% and 85% increase in whole-plant dry mass and leaf area, respectively) when compared with the Upland genotype (no change in dry mass or leaf area). No intraspecific variation in physiological plasticity was detected under CE or TE , and the interactive effects of CE and TE on intraspecific variation in phenotypic plasticity were also largely absent. Overall, TE was a more effective climate factor than CE in exposing genotypic variation in our woody species. Our results contradict the paradigm that genotypes from more variable climates will exhibit greater phenotypic plasticity in future climate regimes. © 2015 John Wiley & Sons Ltd.

A dynamic growth model of macroalgae: Application in an estuary recovering from treated wastewater and earthquake-driven eutrophication

NASA Astrophysics Data System (ADS)

Ren, Jeffrey S.; Barr, Neill G.; Scheuer, Kristin; Schiel, David R.; Zeldis, John

2014-07-01

A dynamic growth model of macroalgae was developed to predict growth of the green macroalga Ulva sp. in response to changes in environmental variables. The model is based on common physiological behaviour of macroalgae and hence has general applicability to macroalgae. Three state variables (nitrogen, carbon and phosphorus) were used to describe physiological processes and functional differences between nutrient and carbon uptakes. Carbon uptake is modelled as a function of temperature, light, algal internal state and water current, while nutrient uptake depends on internal state, temperature and environmental nutrient level. Growth can only occur when nutrients in the environment and in the internal storage pools (N-quota and P-quota) reach threshold levels. Physiological rates follow the Arrhenius relationship and increase exponentially with increasing temperature within the temperature tolerance range of a species. When parameterised and applied to Ulva sp. in the eutrophic Avon-Heathcote Estuary, New Zealand, the model generally reproduced field observations of Ulva sp. growth and abundance. Growth followed a clear seasonal cycle with biomass increasing from early-middle summer, reaching peak values in early autumn and then decreasing. Conversely, N-quotient levels were maximal during the winter months, declining during summer peak growth. These seasonal patterns were collectively driven by temperature, light intensity and nutrients. The model captured the N-quota and growth responses of Ulva sp. to the N-reduction arising from diversion of treated wastewater from the Avon-Heathcote Estuary to an offshore outfall in 2010, and of raw sewage N-discharges resulting from wastewater infrastructure damage caused by the Canterbury earthquakes in 2011. Sensitivity analyses revealed that temperature-related parameters and maximum uptake rate of C were among the most sensitive parameters in predicting biomass. In addition, the earthquake-derived changes in reduction of immersion time and decrease in the start biomass prior to summer blooms were shown to drive considerable declines in summer growth and biomass of Ulva sp.

A closer look at temperature changes with remote sensing

NASA Astrophysics Data System (ADS)

Metz, Markus; Rocchini, Duccio; Neteler, Markus

2014-05-01

Temperature is a main driver for important ecological processes. Time series temperature data provide key environmental indicators for various applications and research fields. High spatial and temporal resolution is crucial in order to perform detailed analyses in various fields of research. While meteorological station data are commonly used, they often lack completeness or are not distributed in a representative way. Remotely sensed thermal images from polar orbiting satellites are considered to be a good alternative to the scarce meteorological data as they offer almost continuous coverage of the Earth with very high temporal resolution. A drawback of temperature data obtained by satellites is the occurrence of gaps (due to clouds, aerosols) that must be filled. We have reconstructed a seamless and gap-free time series for land surface temperature (LST) at continental scale for Europe from MODIS LST products (Moderate Resolution Imaging Sensor instruments onboard the Terra and Aqua satellites), keeping the temporal resolution of four records per day and enhancing the spatial resolution from 1 km to 250 m. Here we present a new procedure to reconstruct MODIS LST time series with unprecedented detail in space and time, at the same time providing continental coverage. Our method constitutes a unique new combination of weighted temporal averaging with statistical modeling and spatial interpolation. We selected as auxiliary variables datasets which are globally available in order to propose a worldwide reproducible method. Compared to existing similar datasets, the substantial quantitative difference translates to a qualitative difference in applications and results. We consider both our dataset and the new procedure for its creation to be of utmost interest to a broad interdisciplinary audience. Moreover, we provide examples for its implications and applications, such as disease risk assessment, epidemiology, environmental monitoring, and temperature anomalies. In the near future, aggregated derivatives of our dataset (following the BIOCLIM variable scheme) will be freely made online available for direct usage in GIS based applications.

Forest biomass variation in Southernmost Brazil: the impact of Araucaria trees.

PubMed

Rosenfield, Milena Fermina; Souza, Alexandre F

2014-03-01

A variety of environmental and biotic factors determine vegetation growth and affect plant biomass accumulation. From temperature to species composition, aboveground biomass storage in forest ecosystems is influenced by a number of variables and usually presents a high spatial variability. With this focus, the aim of the study was to evaluate the variables affecting live aboveground forest biomass (AGB) in Subtropical Moist Forests of Southern Brazil, and to analyze the spatial distribution of biomass estimates. Data from a forest inventory performed in the State of Rio Grande do Sul, Southern Brazil, was used in the present study. Thirty-eight 1-ha plots were sampled and all trees with DBH > or = 9.5cm were included for biomass estimation. Values for aboveground biomass were obtained using published allometric equations. Environmental and biotic variables (elevation, rainfall, temperature, soils, stem density and species diversity) were obtained from the literature or calculated from the dataset. For the total dataset, mean AGB was 195.2 Mg/ha. Estimates differed between Broadleaf and Mixed Coniferous-Broadleaf forests: mean AGB was lower in Broadleaf Forests (AGB(BF)=118.9 Mg/ha) when compared to Mixed Forests (AGB(MF)=250.3 Mg/ha). There was a high spatial and local variability in our dataset, even within forest types. This condition is normal in tropical forests and is usually attributed to the presence of large trees. The explanatory multiple regressions were influenced mainly by elevation and explained 50.7% of the variation in AGB. Stem density, diversity and organic matter also influenced biomass variation. The results from our study showed a positive relationship between aboveground biomass and elevation. Therefore, higher values of AGB are located at higher elevations and subjected to cooler temperatures and wetter climate. There seems to be an important contribution of the coniferous species Araucaria angustifolia in Mixed Forest plots, as it presented significantly higher biomass than angiosperm species. In Brazil, this endangered species is part of a high diversity forest (Araucaria Forest) and has the potential for biomass storage. The results of the present study show the spatial and local variability in aboveground biomass in subtropical forests and highlight the importance of these ecosystems in global carbon stock, stimulating the improvement of future biomass estimates.

Mesoscale Variation of Mechanisms Contributing to Stability in Rocky Shore Communities

PubMed Central

Valdivia, Nelson; González, Andrés E.; Manzur, Tatiana; Broitman, Bernardo R.

2013-01-01

Environmental fluctuations can generate asynchronous species’ fluctuations and community stability, due to compensatory dynamics of species with different environmental tolerances. We tested this hypothesis in intertidal hard-bottom communities of north-central Chile, where a persistent upwelling centre maintains a mosaic in sea surface temperatures (SST) over 10s of kilometres along the shore. Coastal upwelling implies colder and temporally more stable SST relative to downstream sites. Uni- and multivariate analyses of multiyear timeseries of SST and species abundances showed more asynchronous fluctuations and higher stability in sites characterised by warmer and more variable SST. Nevertheless, these effects were weakened after including data obtained in sites affected by less persistent upwelling centres. Further, dominant species were more stable in sites exposed to high SST variability. The strength of other processes that can influence community stability, chiefly statistical averaging and overyielding, did not vary significantly between SST regimes. Our results provide observational evidence supporting the idea that exogenously driven compensatory dynamics and the stabilising effects of dominant species can determine the stability of ecosystems facing environmental fluctuations. PMID:23326592

The Sap Flow Dynamics and Response of Hedysarum scoparium to Environmental Factors in Semiarid Northwestern China.

PubMed

Deng, Jifeng; Ding, Guodong; Gao, Guanglei; Wu, Bin; Zhang, Yuqing; Qin, Shugao; Fan, Wenhui

2015-01-01

Hedysarum scoparium is an important, fast-growing and drought-resistant shrub that has been extensively used for grassland restoration and preventing desertification in semiarid regions of northwestern China. The primary objective of this study was to investigate the diurnal and seasonal variations in stem sap flow (Js) and its relation to environmental factors. The stem heat balance method was applied to plants that were approximately 17 years old (with diameters of 25, 16, 13, and 9 mm at ground level and heights of 3.1, 1.8, 1.7 and 1.4 m) and growing under natural conditions. The vertical soil temperature profile (ST), soil surface heat flux (SoilG), volumetric soil moisture content (SWC) and meteorological variables such as solar radiation (Rn), air temperature (Ta), vapour pressure deficit (VPD), wind speed (Ws) relative humidity (RH) and precipitation (P) were simultaneously measured at a meteorological station on site. Results indicated that Js varied regularly during the diurnal and seasonal term. The nocturnal Js was substantial, with a seasonal variation similar to the patterns of daytime Js. The magnitude of Js changed considerably between sunny and rainy days. Redundancy (RDA) and Kendall's tau analysis suggested that daily Js in large plants was more sensitive to environmental factors, and the variation in daily Js during the growing season could be described by a multiple linear regression against environmental variables including Ta, VPD, Ws, RH, ST, and SoilG. While the nocturnal Js in smaller plants was more sensitive to meteorological factors. Ta, VPD, and Ws were significantly correlated with nighttime Js. The hourly nighttime sap flow rate of H. scoparium corresponded closely to Ta and VPD following a non-linear pattern. The results of this study can be used to estimate the transpiration of H. scoparium.

A multi-year analysis of passage and survival at McNary Dam, 2004-09

USGS Publications Warehouse

Adams, Noah S.; Walker, C.E.; Perry, R.W.

2011-01-01

We analyzed 6 years (2004–09) of passage and survival data collected at McNary Dam to determine how dam operations and environmental conditions affect passage and survival of juvenile salmonids. A multinomial logistic regression was used to examine how environmental variables and dam operations relate to passage behavior of juvenile salmonids at McNary Dam. We used the Cormack-Jolly-Seber release-recapture model to determine how the survival of juvenile salmonids passing through McNary Dam relates to environmental variables and dam operations. Total project discharge and the proportion of flow passing the spillway typically had a positive effect on survival for all species and routes. As the proportion of water through the spillway increased, the number of fish passing the spillway increased, as did overall survival. Additionally, survival generally was higher at night. There was no meaningful difference in survival for fish that passed through the north or south portions of the spillway or powerhouse. Similarly, there was no difference in survival for fish released in the north, middle, or south portions of the tailrace. For subyearling Chinook salmon migrating during the summer season, increased temperatures had a drastic effect on passage and survival. As temperature increased, survival of subyearling Chinook salmon decreased through all passage routes and the number of fish that passed through the turbines increased. During years when the temporary spillway weirs (TSWs) were installed, passage through the spillway increased for spring migrants. However, due to the changes made in the location of the TSW between years and the potential effect of other confounding environmental conditions, it is not certain if the increase in spillway passage was due solely to the presence of the TSWs. The TSWs appeared to improve forebay survival during years when they were operated.

Spatio-Temporal Analyses of Symbiodinium Physiology of the Coral Pocillopora verrucosa along Large-Scale Nutrient and Temperature Gradients in the Red Sea

PubMed Central

Sawall, Yvonne; Al-Sofyani, Abdulmohsin; Banguera-Hinestroza, Eulalia; Voolstra, Christian R.

2014-01-01

Algal symbionts (zooxanthellae, genus Symbiodinium) of scleractinian corals respond strongly to temperature, nutrient and light changes. These factors vary greatly along the north-south gradient in the Red Sea and include conditions, which are outside of those typically considered optimal for coral growth. Nevertheless, coral communities thrive throughout the Red Sea, suggesting that zooxanthellae have successfully acclimatized or adapted to the harsh conditions they experience particularly in the south (high temperatures and high nutrient supply). As such, the Red Sea is a region, which may help to better understand how zooxanthellae and their coral hosts successfully acclimatize or adapt to environmental change (e.g. increased temperatures and localized eutrophication). To gain further insight into the physiology of coral symbionts in the Red Sea, we examined the abundance of dominant Symbiodinium types associated with the coral Pocillopora verrucosa, and measured Symbiodinium physiological characteristics (i.e. photosynthetic processes, cell density, pigmentation, and protein composition) along the latitudinal gradient of the Red Sea in summer and winter. Despite the strong environmental gradients from north to south, our results demonstrate that Symbiodinium microadriaticum (type A1) was the predominant species in P. verrucosa along the latitudinal gradient. Furthermore, measured physiological characteristics were found to vary more with prevailing seasonal environmental conditions than with region-specific differences, although the measured environmental parameters displayed much higher spatial than temporal variability. We conclude that our findings might present the result of long-term acclimatization or adaptation of S. microadriaticum to regionally specific conditions within the Red Sea. Of additional note, high nutrients in the South correlated with high zooxanthellae density indicating a compensation for a temperature-driven loss of photosynthetic performance, which may prove promising for the resilience of these corals under increase of temperature increase and eutrophication. PMID:25137123

Spatio-temporal analyses of Symbiodinium physiology of the coral Pocillopora verrucosa along large-scale nutrient and temperature gradients in the Red Sea.

PubMed

Sawall, Yvonne; Al-Sofyani, Abdulmohsin; Banguera-Hinestroza, Eulalia; Voolstra, Christian R

2014-01-01

Algal symbionts (zooxanthellae, genus Symbiodinium) of scleractinian corals respond strongly to temperature, nutrient and light changes. These factors vary greatly along the north-south gradient in the Red Sea and include conditions, which are outside of those typically considered optimal for coral growth. Nevertheless, coral communities thrive throughout the Red Sea, suggesting that zooxanthellae have successfully acclimatized or adapted to the harsh conditions they experience particularly in the south (high temperatures and high nutrient supply). As such, the Red Sea is a region, which may help to better understand how zooxanthellae and their coral hosts successfully acclimatize or adapt to environmental change (e.g. increased temperatures and localized eutrophication). To gain further insight into the physiology of coral symbionts in the Red Sea, we examined the abundance of dominant Symbiodinium types associated with the coral Pocillopora verrucosa, and measured Symbiodinium physiological characteristics (i.e. photosynthetic processes, cell density, pigmentation, and protein composition) along the latitudinal gradient of the Red Sea in summer and winter. Despite the strong environmental gradients from north to south, our results demonstrate that Symbiodinium microadriaticum (type A1) was the predominant species in P. verrucosa along the latitudinal gradient. Furthermore, measured physiological characteristics were found to vary more with prevailing seasonal environmental conditions than with region-specific differences, although the measured environmental parameters displayed much higher spatial than temporal variability. We conclude that our findings might present the result of long-term acclimatization or adaptation of S. microadriaticum to regionally specific conditions within the Red Sea. Of additional note, high nutrients in the South correlated with high zooxanthellae density indicating a compensation for a temperature-driven loss of photosynthetic performance, which may prove promising for the resilience of these corals under increase of temperature increase and eutrophication.

Wood phenology: from organ-scale processes to terrestrial ecosystem models

NASA Astrophysics Data System (ADS)

Delpierre, Nicolas; Guillemot, Joannès

2016-04-01

In temperate and boreal trees, a dormancy period prevents organ development during adverse climatic conditions. Whereas the phenology of leaves and flowers has received considerable attention, to date, little is known regarding the phenology of other tree organs such as wood, fine roots, fruits and reserve compounds. In this presentation, we review both the role of environmental drivers in determining the phenology of wood and the models used to predict its phenology in temperate and boreal forest trees. Temperature is a key driver of the resumption of wood activity in spring. There is no such clear dominant environmental cue involved in the cessation of wood formation in autumn, but temperature and water stress appear as prominent factors. We show that wood phenology is a key driver of the interannual variability of wood growth in temperate tree species. Incorporating representations of wood phenology in a terrestrial ecosystem model substantially improved the simulation of wood growth under current climate.

[Reproductive effort, fattening index and yield of Arca zebra (Filibranchia: Arcidae) by length and its association with environmental variables, Sucre, Venezuela].

PubMed

Lista, María; Velásquez, Carlos; Prieto, Antulio; Longart, Yelipza

2016-06-01

Arca zebra is a mollusk of commercial value and a major socioeconomic fishery in Northeastern Venezuela. The present study aimed to evaluate the reproductive effort (RE), fattening index (FI) and yield (Y) in different size groups of A. zebra from the morro Chacopata, Venezuela. For this, monthly samplings from June 2008 and June 2009, were undertaken, and the bivalves obtained were distributed in three length groups: I (30.1 to 50.0 mm), II (50.1 to 70.0 mm) and III (> 70.0 mm). Monthly RE, FI and Y were determined based on bivalve changes in volume of fresh meat (VFM), intervalvar volume (IV), dry gonad biomass (DW), dry biomass of the organism without gonad (DWs), fresh biomass of meat (FBM) and total biomass including shell (TBIS). Besides, environmental variables such as temperature, salinity, dissolved oxygen, total organic and inorganic seston and chlorophyll a were measured monthly. There was great variation in the DW between length groups (relevant for II and III): increased from June until late September 2008, was followed by a marked decrease in October 2008, recovered in the following months, and decreased in January 2009, with a slight increase until May 2009; these changes were associated with variations in sea temperature. The weight of the gonad (DW) influenced the RE, FI and Y, as these reached their peaks in the months where there was higher gonadal production, indicating the influence of temperature on A. zebra reproduction.

Influence of abiotic and environmental factors on the density and infection prevalence of Ixodes pacificus (Acari:Ixodidae) with Borrelia burgdorferi.

PubMed

Swei, A; Meentemeyer, R; Briggs, C J

2011-01-01

The abiotic and biotic factors that govern the spatial distribution of Lyme disease vectors are poorly understood. This study addressed the influence of abiotic and biotic environmental variables on Ixodes pacificus Cooley & Kohls (Acari:Ixodidae) nymphs, because it is the primary vector of Borrelia burgdorferi Johnson, Schmidt, Hyde, Steigerwaldt & Brenner in the far-western United States. Three metrics of Lyme disease risk were evaluated: the density of nymphs, the density of infected nymphs, and the nymphal infection prevalence. This study sampled randomly located plots in oak (Quercus spp.) woodland habitat in Sonoma County, CA. Each plot was drag-sampled for nymphal ticks and tested for B. burgdorferi infection. Path analysis was used to evaluate the direct and indirect relationship between topographic, forest structure and microclimatic variables on ticks. Significant negative correlations were found between maximum temperature in the dry season and the density of infected ticks in 2006 and tick density in 2007, but we did not find a significant relationship with nymphal infection prevalence in either year. Tick density and infected tick density had an indirect, positive correlation with elevation, mediated through temperature. This study found that in certain years but not others, temperature maxima in the dry season may constrain the density and density of infected I. pacificus nymphs. In other years, biotic or stochastic factors may play a more important role in determining tick density.

The impact of warming on greenhouse gas fluxes: an experimental comparison which reveals the varied response of ecosystems to climate change.

NASA Astrophysics Data System (ADS)

Stockdale, James; Ineson, Philip

2016-04-01

Modelled predictions of the response of terrestrial systems to climate change are highly variable, yet the response of net ecosystem exchange (NEE) is a vital ecosystem behaviour to understand due to its inherent feedback to the carbon cycle. The establishment and subsequent monitoring of replicated experimental manipulations are a direct method to reveal these responses, yet are difficult to achieve as they typically resource-heavy and labour intensive. We actively manipulated the temperature at three agricultural grasslands in southern England and deployed novel 'SkyLine' systems, recently developed at the University of York, to continuously monitor GHG fluxes. Each 'SkyLine' is a low-cost and fully autonomous technology yet produces fluxes at a near-continuous temporal frequency and across a wide spatial area. The results produced by 'SkyLine' enable the detail response of each system to increased temperature over diurnal and seasonal timescales. Unexpected differences in NEE are shown between superficially similar ecosystems which, upon investigation, suggest that interactions between a variety of environmental variables are key and that knowledge of pre-existing environmental conditions help to predict a systems response to future climate. For example, the prevailing hydrological conditions at each site appear to affect its response to changing temperature. The high-frequency data shown here, combined with the fully-replicated experimental design reveal complex interactions which must be understood to improve predictions of ecosystem response to a changing climate.

Environmental and Hydroclimatic Sensitivities of Greenhouse Gas (GHG) Fluxes from Coastal Wetlands

NASA Astrophysics Data System (ADS)

Abdul-Aziz, O. I.; Ishtiaq, K. S.

2016-12-01

We computed the reference environmental and hydroclimatic sensitivities of the greenhouse gas (GHG) fluxes (CO2 and CH4) from coastal salt marshes. Non-linear partial least squares regression models of CO2 (net uptake) and CH4 (net emissions) fluxes were developed with a bootstrap resampling approach using the photosynthetically active radiation (PAR), air and soil temperatures, water height, soil moisture, porewater salinity, and pH as predictors. Analytical sensitivity coefficients of different predictors were then analytically derived from the estimated models. The numerical sensitivities of the dominant drivers were determined by perturbing the variables individually and simultaneously to compute their individual and combined (respectively) effects on the GHG fluxes. Four tidal wetlands of Waquoit Bay, MA — incorporating a gradient in land-use, salinity and hydrology — were considered as the case study sites. The wetlands were dominated by native Spartina Alterniflora, and characterized by high salinity and frequent flooding. Results indicated a high sensitivity of CO2 fluxes to temperature and PAR, a moderate sensitivity to soil salinity and water height, and a weak sensitivity to pH and soil moisture. In contrast, the CH4 fluxes were more sensitive to temperature and salinity, compared to that of PAR, pH, and hydrologic variables. The estimated sensitivities and mechanistic insights can aid the management of coastal carbon under a changing climate and environment. The sensitivity coefficients also indicated the most dominant drivers of GHG fluxes for the development of a parsimonious predictive model.

Divergent climate response on hydraulic-related xylem anatomical traits of Picea abies along a 900-m altitudinal gradient.

PubMed

Castagneri, Daniele; Petit, Giai; Carrer, Marco

2015-12-01

Climate change can induce substantial modifications in xylem structure and water transport capacity of trees exposed to environmental constraints. To elucidate mechanisms of xylem plasticity in response to climate, we retrospectively analysed different cell anatomical parameters over tree-ring series in Norway spruce (Picea abies L. Karst.). We sampled 24 trees along an altitudinal gradient (1200, 1600 and 2100 m above sea level, a.s.l.) and processed 2335 ± 1809 cells per ring. Time series for median cell lumen area (MCA), cell number (CN), tree-ring width (RW) and tree-ring-specific hydraulic conductivity (Kr) were crossed with daily temperature and precipitation records (1926-2011) to identify climate influence on xylem anatomical traits. Higher Kr at the low elevation site was due to higher MCA and CN. These variables were related to different aspects of intra-seasonal climatic variability under different environmental conditions, with MCA being more sensitive to summer precipitation. Winter precipitation (snow) benefited most parameters in all the sites. Descending the gradient, sensitivity of xylem features to summer climate shifted mostly from temperature to precipitation. In the context of climate change, our results indicate that higher summer temperatures at high elevations will benefit cell production and xylem hydraulic efficiency, whereas reduced water availability at lower elevations could negatively affect tracheids enlargement and thus stem capacity to transport water. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.