Positive Effect Of Temperature Research Articles

Seasonal dynamics of spatial distributions and overlap between Northeast Arctic cod (Gadus morhua) and capelin (Mallotus villosus) in the Barents Sea.

The trophic link between cod (Gadus sp.) and capelin (Mallotus sp.) is important in many panarctic ecosystems. Since the early 2000s, the Northeast Arctic cod stock (G. morhua) in the Barents Sea has increased greatly, and the sea has been exceptionally warm. Such changes have potentially large effects on species distributions and overlap, which in turn could affect the strength of species interactions. Due to its high latitude location, the Barents Sea has strong seasonal variation in physical conditions and interactions. To study drivers of variation in cod-capelin overlap, we use data from two annual surveys run in winter and in autumn of 2004–2015. We first model winter and autumn spatial distributions of mature and immature cod and capelin. We then calculate overlap from model predictions on a grid with similar spatial resolution as the survey data. Our approach allowed us to interpret changes in overlap as species-specific effects of stock size and temperature, while accounting for sampling variation due to sampling time and depth. We found that during winter both species expanded their distribution in response to increased stock sizes, but how strongly and where the expansion occurred varied. The effect of temperature on distributions varied in space, and differed for cod and capelin and for different components of the two species. The results for autumn were clearer and more consistent. Both species expanded their distribution areas as their stock sizes increased. A positive effect of temperature was found in the north-eastern Barents Sea, where temperatures were lowest at the start of the study. Overlap increased and shifted north-eastwards during the study period and remained high despite a decline in the capelin stock. The increased overlap during autumn could mainly be attributed to the shift in cod distribution with increased cod stock biomass.

Broad, Multi-Year Sampling Effort Highlights Complex Dynamics of the Tick-Borne PathogenEhrlichia chaffeensis(Rickettsiales: Anaplasmatacae)

Ehrlichia chaffeensis (Rickettsiales: Anaplasmatacae), an understudied bacterial pathogen emerging in the eastern United States, is increasing throughout the range of its vector, the lone star tick [Amblyomma americanum, L. (Acari: Ixodidae)]. To mitigate human disease risk, we must understand what factors drive E. chaffeensis prevalence. Here, we report patterns of E. chaffeensis prevalence in southeastern Virginia across 4 yr and ask how seasonal weather patterns affect variation in rates of E. chaffeensis occurrence. We collected A. americanum nymphs at 130 plots across southeastern Virginia in 2012, 2013, 2015, and 2016, and used polymerase chain reaction and gel electrophoresis to test for the presence of E. chaffeensis DNA. Prevalence estimates varied among years, ranging from 0.9% to 3.7%, and persistence of E. chaffeensis occurrence varied across space, with some sites never testing positive, and one site testing positive every year. Using generalized linear mixed-effects models, we related E. chaffeensis occurrence to temperature, humidity, vapor-pressure deficit, and precipitation during seasons up to 21 mo prior to sampling. Surprisingly, all support was lent to a positive effect of temperature during the previous fall and winter (i.e., prior to the nymphs' hatching), which we hypothesize to influence reservoir host population dynamics through changes to mortality or natality. Although further work is necessary to truly elucidate the mechanisms at play, our study shows E. chaffeensis distribution to be very dynamic across multiple dimensions, demanding broad concerted monitoring efforts that can consider both space and time.

A Thermal Protective Compound Elastic at Negative Temperatures

A compound based on polyether urethane rubber with end epoxy urethane groups and epoxy oligomers for the protection of products made of highly filled polymer compositions subject to the effect of positive and negative temperatures was developed. Its curing regularities and mechanical properties were studied. It was shown that the compound retains elasticity at the temperatures of up to –40°C and surpasses the currently used compound in terms of mechanical characteristics.

Influence of water temperature on physiological performance of the sea cucumber Holothuria moebii

We conducted a laboratory investigation of the influence of water temperature on the physiological performance—including faecal production, oxygen consumption, and ammonia excretion rates—of the sea cucumber Holothuria moebii. Adult H. moebii (34.39 ± 5.17 g, wet weight) were exposed to four experimental temperatures (15, 20, 25, and 30°C), which represented the temperature range in their natural habitat. Results showed that the maximum faecal production rate was observed at 30°C (71.06 ± 7.21 mg g−1 day−1), which was significantly higher than at other temperatures. This indicated that, at a high temperature, H. moebii could take in more energy than at lower temperatures. The oxygen consumption rate increased with water temperature, and the minimum value observed at 15°C (5.68 ± 0.86 µg O2 g−1 hr−1) was significantly lower than at other temperatures. The low oxygen consumption rate at 15°C indicated a low level of energy production by H. moebii during winter. The maximum ammonia excretion rate observed at 30°C (0.029 ± 0.007 µmol g−1 hr−1) was significantly higher than at other temperatures, and the positive effect of water temperature on nitrogen catabolism indicated the possibility of H. moebii being in a better nutritional status during the hot season. The minimum value of O/N ratio at 15°C (25.55 ± 4.70) indicated the mixed utilization of protein- and carbon-based substrates during winter, while the high value of O/N ratios in other treatments (all >32) indicated the dominance of carbohydrate and/or lipid metabolism in warm and hot seasons. The results of this study suggest that H. moebii is more suitable for rearing in warm waters (>20°C).

A Panel Data Model-Based Multi-Factor Predictive Model of Highway Electromechanical Equipment Faults

Highway electromechanical equipment faults can be caused by multiple factors. To study the effects of these factors on electromechanical equipment faults, a panel data model was developed. Traffic flow, temperature difference, relative humidity, and wind speed were selected as explanatory variables, with the electromechanical faults being the response variable. The data was based on an investigation of electromechanical equipment faults, and the above-mentioned environmental variables were collected from six highways in Beijing during 2012–2013. Panel data models for pooled regression models and individual fixed and random effects were established. A unit root test was performed on the data sequence. Finally, the F-test and the Hausman-test were used to compare the three predictive models and determine the optimal one. It was found that the individual fixed effects model was superior to the other two. Positive effects of temperature, relative humidity, and wind speed on the electromechanical equipment faults were found to be significant, while traffic flow had a significant negative effect on the electromechanical equipment faults. This paper included four factors, more influences from other factors should be discussed in the further research. In general, this paper showed the importance of traffic flow to highway electromechanical equipments and can be potentially used to increase the service life of the equipments. The contribution of this work would provide theoretical support for fault prediction and emphasize the importance of environment-related preventive maintenance on the highway electromechanical equipment.

Abundance, infestation and disease transmission by thrips on groundnut as influenced by climatic variability at Kadiri, Andhra Pradesh

Abundance, infestation and disease transmission by thrips studied on groundnut at Kadiri of Anantapur (Andhra Pradesh) over six kharif seasons of 2011-16 indicated significantly higher abundance of thrips in 2016 over 2011 to 2015 with infestations on par among 2013, 2014 and 2016 and higher over other seasons. Peanut bud necrosis disease (PBND) transmission by thrips was significantly lower in 2015 and 2016 and higher in 2014. Associations of abundance of thrips with infestation and PBND were significant. Significant influence of PBND by the thrips infestation of only the current week implied significance of concurrent population in disease transmission.Significant positive effect of minimum temperature on incidence of PBND and negative effect of rainfall on thrips infestation were noted.Predictions of thrips abundance, infestation and PBND through multiple linear regression (MLR) models revealed positive influence of minimum temperature lagged by a week. Distribution of rainfall over its amount associated with thrips infestation besides negative role of wind with PBND was noted. Prediction models of PBND incidence combining weather and thrips abundance (R2:0.39) and weather and infestation (R2:0.53) showed that the PBND incidence was dependent on relative humidity andprevalent wind over previous two weeks in addition to thrips abundance or infestation.

Unfolding Extraordinary Positive Effect of High Temperature and High Irradiance on DC Power Output of a Multicrystalline PV Module: A Case Study of Western Rajasthan

Unfolding Extraordinary Positive Effect of High Temperature and High Irradiance on DC Power Output of a Multicrystalline PV Module: A Case Study of Western Rajasthan

Context-dependent effects of temperature on starvation resistance in Drosophila melanogaster: Mechanisms and ecological implications

Temperature can modulate the responses of ectotherms to environmental stressors, such as food shortage. Temperature-mediated plasticity in starvation resistance can arise by changes in the amount of energy stored, the speed of energy expenditure, or the threshold energy reserves required for survival. However, few studies have investigated how temperature affects these physiological mechanisms underlying starvation resistance. In this study, we first examined the mechanistic basis of the temperature dependence of starvation resistance in Drosophila melanogaster. We then tested whether the effects of temperature on starvation resistance would depend on diet and developmental stage in this species. We found that exposure to high temperature during starvation significantly reduced the capacity of D. melanogaster to resist starvation. This warming-induced decrease in starvation resistance was mainly caused by faster depletion of body lipids and not by lower threshold lipid content for survival. D. melanogaster exposed to higher temperatures during feeding accumulated more body lipids and thus became more starvation resistant. Such positive effect of high feeding temperature on starvation resistance was pronounced when D. melanogaster consumed carbohydrate-rich diets. D. melanogaster raised as larvae at low temperature (18 °C) had a weaker starvation resistance at adult emergence compared to those raised at higher temperatures (23 and 28 °C). These results demonstrate that the effects of temperature on starvation responses are highly context-dependent in D. melanogaster.

Body size shifts influence effects of increasing temperatures on ectotherm metabolism

AbstractAimWarmer temperatures directly increase metabolic rates of ectotherms, but temperature also indirectly affects metabolic rates. Higher temperatures result in smaller body sizes and associated decreases in metabolic rates, and it remains unknown whether this indirect effect of temperature increase could mitigate the direct positive effect of temperature on metabolic rate. Here, we assess whether temperature‐induced shifts in body size are likely to offset the direct influence of temperature on metabolic rate.LocationGlobal.Time period1940–2011.Major taxa studiedEctotherms.MethodsWe compiled literature‐derived data on mass and temperature for 109 ectotherm species raised at various constant temperatures. Using an allometric equation to estimate metabolic rate from size and temperature, we determined the body masses necessary for species to maintain constant metabolic rates under increased temperatures. We also calculated and compared (a) change in metabolic rate attributable to increased temperature where body size does not change with (b) change in metabolic rate including empirical size change.ResultsWarmer temperatures resulted in increased metabolic rate estimates, but this was partly offset by decreased body sizes for the majority of species. For most species, observed decreases in body size at higher temperatures were insufficient to avoid metabolic rate increases.Main conclusionsAlthough the indirect effect of temperature on metabolic rate via body size is not sufficient to counterbalance the direct effect, it limits the magnitude of the increase in metabolic rate. Thus, in a warming climate, ectotherms are likely to experience increases in energy use that are smaller than anticipated. Given that metabolic rates have substantial, diverse impacts on individuals, populations, and ecosystems, these indirect effects of temperature change will have complex cascading effects on ecological communities, but the impacts of increases in metabolic rate of these varying magnitudes are unknown.

Extraction of astaxanthin from microalga Haematococcus pluvialis in red phase by using generally recognized as safe solvents and accelerated extraction

Solvent Extraction was tested to extract astaxanthin from Haematococcus pluvialis in red phase (HPR), by investigating effects of solvents, extraction pressure and temperature. Astaxanthin isomers were identified and quantified in the extract. The performances of acetone and ethanol, Generally Recognized As Safe (GRAS) solvents, were explored. Negligible effect of pressure was found, while with increasing extraction temperature astaxanthin recovery increased till a maximum value, beyond which thermal degradation seemed to be greater than the positive effect of temperature on extraction. Furthermore, to maximize the extraction yield of astaxanthin, mechanical pre-treatment of HPR biomass was carried out and several extraction runs were consecutively performed. Experimental results showed that after the mechanical pre-treatment the astaxanthin recovery strongly increased while a single extraction run of 20 min was sufficient to extract more than 99% of total astaxanthin extracted. After pre-treatment, maximum recovery of about 87% was found for acetone (pressure = 100 bar; temperature = 40 °C; total time = 60 min).

Impacts of warming on top-down and bottom-up controls of periphyton production

Global warming profoundly impacts the functioning of aquatic ecosystems. Nonetheless, the effect of warming on primary producers is poorly understood, especially periphyton production, which is affected both directly and indirectly by temperature-sensitive top-down and bottom-up controls. Here, we study the impact of warming on gross primary production in experimental ecosystems with near-realistic foodwebs during spring and early summer. We used indoor mesocosms following a temperate temperature regime (control) and a warmed (+4 °C) treatment to measure biomass and production of phytoplankton and periphyton. The mesocosms’ primary production was dominated by periphyton (>82%) during the studied period (April-June). Until May, periphyton production and biomass were significantly higher in the warm treatment (up to 98% greater biomass compared to the control) due to direct temperature effects on growth and indirect effects resulting from higher sediment phosphorus release. Subsequently, enhanced grazer abundances seem to have counteracted the positive temperature effect causing a decline in periphyton biomass and production in June. We thus show, within our studied period, seasonally distinct effects of warming on periphyton, which can significantly affect overall ecosystem primary production and functioning.

Prediction of Sporulation and Germination by the Spider Mite Pathogenic Fungus Neozygites floridana (Neozygitomycetes: Neozygitales: Neozygitaceae) Based on Temperature, Humidity and Time.

Neozygites floridana is a pathogenic fungus and natural enemy of the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), which is an important polyphagous plant pest. The aim of this study was to reveal and predict what combination of temperature, relative humidity (RH), and time that enables and promotes primary conidia production and capilliconidia formation in N. floridana (Brazilian isolate ESALQ 1420), in both a detached leaf assay mimicking climatic conditions in the leaf boundary layer and in a semi-field experiment. In the detached leaf assay, a significant number of conidia were produced at 90% RH but the highest total number of primary conidia and proportion of capilliconidia was found at 95 and 100% RH at 25 °C. Positive temperature and RH effects were observed and conidia production was highest in the 8 to 12 h interval. The semi-field experiment showed that for a >90% probability of N. floridana sporulation, a minimum of 6 h with RH >90% and 10 h with temperatures >21 °C, or 6 h with temperatures >21 °C and 15 h with RH >90% was needed. Our study identified suitable conditions for primary- and capilliconidia production in this Brazilian N. floridana isolate. This information provides an important base for building models of a Decision Support System (DSS) where this natural enemy may be used as a tool in Integrated Pest Management (IPM) and a base for developing in vivo production systems of N. floridana.

Effect of solar light on the decrease of microbial contamination in facultative stabilization pond

One of the indexes of stabilization pond is the presence of coliform bacteria in water and wastewater. This study aimed to determine the effect of solar light on coliform variations in stabilization pond. In this experimental study, the effect of light, pH (<7, 7.1–8, 8.1–9), and temperature (10 oC and 30 oC) on facultative stabilization pond was studied for six months. The sampling was accomplished weekly. Coliform colonies were measured using the nine tube fermentation method. The coliform deterioration constant was calculated using the Maraise model. The data were analyzed using SPSS version 20. The effect of light on coliform deterioration constant was negative. Also, low pH increased the coliform death. No significant statistical difference was seen at 10 oC and 30 oC (P < 0.05). Low temperature cannot be adherence for facultative stabilization pond. Regarding the positive effect of temperature on the coliform death, use of facultative stabilization pond in a warm climate is suggested.

Modelling Trends of Climatic Variability and Malaria in Ghana Using Vector Autoregression.

Malaria is considered endemic in over hundred countries across the globe. Many cases of malaria and deaths due to malaria occur in Sub-Saharan Africa. The disease is of great public health concern since it affects people of all age groups more especially pregnant women and children because of their vulnerability. This study sought to use vector autoregression (VAR) models to model the impact of climatic variability on malaria. Monthly climatic data (rainfall, maximum temperature, and relative humidity) from 2010 to 2015 were obtained from the Ghana Meteorological Agency while data on malaria for the same period were obtained from the Ghana Health Service. Results of the Granger and instantaneous causality tests led to a conclusion that malaria is influenced by all three climatic variables. The impulse response analyses indicated that the highest positive effect of maximum temperature, relative humidity, and rainfall on malaria is observed in the months of September, March, and October, respectively. The decomposition of forecast variance indicates varying degree of malaria dependence on the climatic variables, with as high as 12.65% of the variability in the trend of malaria which has been explained by past innovations in maximum temperature alone. This is quite significant and therefore, policy-makers should not ignore temperature when formulating policies to address malaria.

Resilience to fire and climate seasonality drive the temporal dynamics of ant-plant interactions in a fire-prone ecosystem

Animal-plant interactions have a major influence on ecosystem structure and functioning. Understanding to what extent the temporal dynamics of interactions is determined by climate and disturbances is thus relevant to predict ecological and evolutionary outcomes in a changing world. Here, we assessed whether the temporal dynamics of ant-plant interactions in a mountainous fire-prone ecosystem is driven by seasonal variation in abiotic conditions, and to what extent fire disturbance alters this dynamic. We also examined the thermal responses of foliage-dwelling ants in order to predict the effects of seasonal oscillations of temperature on ant activity. To do so, we monitored ant-plant associations in 35 sampling plots for one year before an unmanaged fire has occurred. Then, 26 burned and nine unburned plots were monitored for another year after fire. We found that warmer and wetter conditions let to increases in the diversity and frequency of ant-plant interactions, mainly via upturns in plant resource availability and ant foraging activity. Beyond the positive effects of temperature on interaction networks, however, ant species exhibited a low heterogeneity and a huge overlap in thermal niches. Moreover, fire has led to short-term negative effects on the diversity and frequency of interactions in ant-plant networks. In spite of it, these network metrics in burned plots took up to half a year to return to similar levels from unburned plots, highlighting the resilience of ant-plant interactions after fire disturbances. This study shows that wide thermal niches of ant species and fire resilience likely beget ant-plant networks reliability over seasons. The high overlap and broad thermal niches of ant species interacting with plant resources suggest that ant diversity plays a minor role in the tolerance against climatic changes in this fire-adapted community. These findings open a new pathway to explore thermal responses of species and their ecological interactions in broader gradients of environmental conditions and ecosystem disturbances. We advocate that long-term studies comprising assisted burnings are desirable to forecast the impact of fire regimes and how their synergy with climate would affect the functioning of fire-prone ecosystems. Lastly, this study adds evidence that studied interaction networks can be useful to monitor the impacts of environmental changes such as anthropogenic disturbances, being representative of many even more complex species interactions in ecosystems.

Species composition and forest structure explain the temperature sensitivity patterns of productivity in temperate forests

Abstract. Rising temperatures due to climate change influence the wood production of forests. Observations show that some temperate forests increase their productivity, whereas others reduce their productivity. This study focuses on how species composition and forest structure properties influence the temperature sensitivity of aboveground wood production (AWP). It further investigates which forests will increase their productivity the most with rising temperatures. We described forest structure by leaf area index, forest height and tree height heterogeneity. Species composition was described by a functional diversity index (Rao's Q) and a species distribution index (ΩAWP). ΩAWP quantified how well species are distributed over the different forest layers with regard to AWP. We analysed 370 170 forest stands generated with a forest gap model. These forest stands covered a wide range of possible forest types. For each stand, we estimated annual aboveground wood production and performed a climate sensitivity analysis based on 320 different climate time series (of 1-year length). The scenarios differed in mean annual temperature and annual temperature amplitude. Temperature sensitivity of wood production was quantified as the relative change in productivity resulting from a 1 ∘C rise in mean annual temperature or annual temperature amplitude. Increasing ΩAWP positively influenced both temperature sensitivity indices of forest, whereas forest height showed a bell-shaped relationship with both indices. Further, we found forests in each successional stage that are positively affected by temperature rise. For such forests, large ΩAWP values were important. In the case of young forests, low functional diversity and small tree height heterogeneity were associated with a positive effect of temperature on wood production. During later successional stages, higher species diversity and larger tree height heterogeneity were an advantage. To achieve such a development, one could plant below the closed canopy of even-aged, pioneer trees a climax-species-rich understorey that will build the canopy of the mature forest. This study highlights that forest structure and species composition are both relevant for understanding the temperature sensitivity of wood production.

Population Density of Potato Tuber Moth, Phthoremaea operculella (Zeller) Lepidoptera : Gelechidae ) Infesting Potato Plants In The Field.

The present study was conducted during 2014, 2105 and 2016 early summer seasons for potato ( kara, variety ) was performed under the field conditions , the experimental field was selected at a private farms at Shepa elnakaria village, Zagazig district and new Salhia, Hosinia district, Sharkia governorate. The present study aimed to study the impact of type soils (clay and sandy soil) on population density of P. operculella larvae infesting potato plants cultivated during 2014, 2015 and 2016 early summer seasons , evaluation infestation % to potato tubers and the effect of some climatic change on population density under field conditions. The statistical analysis of the total mean number of P. operculella larvae showed significant differentiation. The results show that the population density of P. operculella larvae was higher on sandy soil (518 individuals / 120 leaves) than the clay soil (332 individual / 120 leaves), These results revealed significant positive effects of maximum and minimum temperature and DP on population density of P. operculella during the first season 2014 in clay soil and sand soil . The combined effect (E.V) of these ecological factors on P. operculella showed that these factors were responsible as a group for 84 %, 15% and 35 % effects on the population density of P. operculella throughout seasons (2014, 2015 and 2016) in clay and sandy soil , also, these factors were responsible as a group for 72 %, 64% and 26 % effects on the population density.

Experimental Study of Hydrogen Production Using Solar Energy in Ouargla (South East Algeria)

This paper presents an experimental study of solar hydrogen production via electrolysis of water (conversion of solar energy into chemical energy), and thus, a direct link between the electrolyser (Hoffman voltammeter) and two photovoltaic panels should be present. Sodium hydroxide at a low concentration is used in the experiment. The experimental temperature is the temperature of the ambient environment. The experiment was conducted over 45 days spread over most of the months of the year. This represents the first experiment for the Ouargla region with such a long duration. We focused on measuring four important parameters: solar irradiation, the voltage produced by the two photovoltaic panels, the current used in the electrolysis and the flow of hydrogen; these parameters were evaluated throughout the day from 8 am until sunset. This study shows the changes in solar irradiation, voltage, and current, as well as hydrogen flow during the course of a day, month, and the year. It also demonstrates the extent of the negative effect of seasonal temperature on the efficiency of photovoltaic cells and by contrast, the extent of the positive effect of seasonal temperature on the hydrogen production process.

Extrinsic factors affecting otolith chemistry – implications for interpreting migration patterns in a diadromous fish

Much has been revealed about fish migration, including diadromous behaviour, through the use of otolith chemistry. Manipulative experiments assist with unravelling information on otolith chemical composition and incorporation thereby answering specific questions on diadromous movements. In this study, a laboratory-based experiment was used to determine the relative and interactive effects of salinity and water temperature on the composition of three key elements (Sr, Ba and Mg) within the otolith of a catadromous fish, Percalates novemaculeata, endemic to south-eastern Australia. Otolith incorporation of Sr and Ba was positively related to ambient water concentration, whereas Mg incorporation was not. Sr and Ba increased and decreased significantly across salinity gradients, respectively, with minor positive effects of temperature also being detected. Salinity and temperature interacted to significantly affect the elemental concentration ratios for Ba: Ca in otoliths. Discrimination between fresh water and marine environments shows promise for interpreting P. novemaculeata residency based on these elements alone. However, deciphering finer scale movements within estuarine environments may be difficult. Our data highlights the importance of multifactorial validation experiments and suggests complementary use of multiple approaches for unravelling species-specific patterns of fish movement and habitat use.

Outdoor pilot-scale cultivation of Spirulina sp. LEB-18 in different geographic locations for evaluating its growth and chemical composition

This study evaluated whether outdoor cultivation of Spirulina sp. in different geographical locations affected its growth and biomass quality, with respect to the chemical composition, volatile compound and heavy metal content, and thermal stability. The positive effect of solar radiation and temperature on biomass productivity in Spirulina sp. cultivated in the northeast was directly related to its improved nutritional characteristics, which occurred with an increase in protein, phycocyanin, and polyunsaturated fatty acid (mainly γ-linolenic) content. The biomass produced in Northeast and South Brazil showed high thermal stability and had volatile compounds that could be used as biomarkers of Spirulina, and their parameters were within the limits of internationally recognized standards for food additives; hence, they have been considered safe foods. However, the growth of crops in south Brazil occurred at lower rates due to low temperatures and luminous intensities, indicative of the robustness of microalgae in relation to these parameters.