Daily Temperature Fluctuations Research Articles

Corals survive severe bleaching event in refuges related to taxa, colony size, and water depth

Marine heatwaves are increasing in frequency and duration, threatening tropical reef ecosystems through intensified coral bleaching events. We examined a strikingly variable spatial pattern of bleaching in Moorea, French Polynesia following a heatwave that lasted from November 2018 to July 2019. In July 2019, four months after the onset of bleaching, we surveyed > 5000 individual colonies of the two dominant coral genera, Pocillopora and Acropora, at 10 m and 17 m water depths, at six forereef sites around the island where temperature was measured. We found severe bleaching increased with colony size for both coral genera, but Acropora bleached more severely than Pocillopora overall. Acropora bleached more at 10 m than 17 m, likely due to higher light availability at 10 m compared to 17 m, or greater daily temperature fluctuation at depth. Bleaching in Pocillopora corals did not differ with depth but instead varied with the interaction of colony size and Accumulated Heat Stress (AHS), in that larger colonies (> 30 cm) were more sensitive to AHS than mid-size (10–29 cm) or small colonies (5–9 cm). Our findings provide insight into complex interactions among coral taxa, colony size, and water depth that produce high spatial variation in bleaching and related coral mortality.

Daily temperature fluctuation interacts with the mean temperature to increase the toxicity of a pyrethroid insecticide in a moth

Climate change complicates ecotoxicology studies because species responses to pesticides depend on temperature. Classically illustrated by the effect of constant laboratory temperatures, a recent review revealed that the toxicity of pesticides is also often increased by daily temperature fluctuations. Here, we investigated the combined effects of daily temperature fluctuation and mean temperature on the toxicity of two insecticides in the moth Spodoptera littoralis. Our study tested the toxicity of chlorpyrifos and deltamethrin on larvae of six experimental groups that crossed three treatments of daily temperature fluctuations (0, 5 or 10 °C) and two treatments of mean temperatures (25 or 33 °C). We showed that daily temperature fluctuation increased larval mortality induced by chlorpyrifos and deltamethrin. However, the response differed between the organophosphorus insecticide chlorpyrifos and the pyrethroid insecticide deltamethrin. The increase in chlorpyrifos toxicity by daily temperature fluctuation did not differ between mean temperatures of 25 and 33 °C. Remarkably, the increase in deltamethrin toxicity by daily temperature fluctuation was dependent on the crossed effects of the amplitude of daily fluctuation and mean temperature. This increase in deltamethrin toxicity occurred with a daily fluctuation of only 5 °C for larvae reared at 25 °C and a daily fluctuation of 10 °C in larvae reared at 33 °C. To confidently quantify the responses of insecticide toxicity to temperature, future ecotoxicology studies will have to evaluate the generality of the interaction between the effects of daily temperature fluctuation and mean temperature.

Shoals in troubled waters? The impact of rising temperatures on metabolism, foraging, and shoaling behavior in mixed-species shoals.

Rising water temperatures across aquatic habitats, in the current global climate change scenario, can directly affect metabolism and food intake in fish species. This can potentially alter their physiological, behavioral, and shoaling properties. In the current study, we examined the effects of high temperatures on metabolism, foraging, and shoaling in tropical fish. Mixed-species (comprising flying barbs, zebrafish, and gambusia) and single-species (flying barbs and zebrafish) shoals were conditioned for 45 days to three kinds of temperature regimes: the current temperature regime (CTR), in which shoals were maintained at water temperature of 24°C (i.e., the current mean temperature of their habitat), the predicted temperature regime (PTR) at 31°C (i.e., simulating conditions projected for their habitat in 2100), and the dynamic temperature regime (DTR), which experienced daily temperature fluctuations between 24 and 31°C (i.e., resembling rapid temperature changes expected in their natural environments). We found species-specific responses to these temperature regimes. Flying barbs exhibited significantly lower body weight at PTR but maintained consistent muscle glycogen content across all temperature regimes. In contrast, zebrafish and gambusia displayed significantly elevated muscle glycogen content at PTR, with similar body weights across all three temperature regimes. Cohesion within flying barb shoals and cohesion/polarization in mixed-species shoals decreased significantly at PTR. Shoals exposed to DTR exhibited intermediate characteristics between those conditioned to CTR and PTR, suggesting that shoals may be less impacted by dynamic temperatures compared to prolonged high temperatures. This study highlights species-specific metabolic responses to temperature changes and their potential implications for larger-scale shoal properties.

Temporary Structural Health Monitoring of Historical Széchenyi Chain Bridge

A temporary monitoring system was installed on the 175-year-old historical Széchenyi Chain Bridge during its reconstruction. The bridge is in the downtown area in the capital city of Hungary and plays a significant role in the city life of Budapest. Six-month-long measurements were conducted during the reconstruction process of the bridge, yielding crucial insights into the structural behaviour of the historical structure. The measurement results were evaluated; the findings encompass the rotation capacity of the pins between the chain elements and the structural response to temperature changes. This information helped the decision-making between 2021 and 2023 by the designers and construction company during the reconstruction. For instance, daily temperature fluctuations resulted in increased bending moments in the chain elements, rising up to 158% compared to the values observed during a proof load test in 2018. Furthermore, the measurements reveal an approximate 42% increase in normal forces compared to the proof load test, which highlights the high sensitivity of chain bridges to temperature fluctuations, where geometric stiffness plays a crucial role. Reconstruction, namely reducing self-weight, notably intensifies the impact on normal forces and bending moments. These outcomes strongly emphasize the dominance of the dead load and self-weight in the case of chain bridges.

Modifications to gene body methylation do not alter gene expression plasticity in a reef-building coral.

As coral reefs continue to decline due to climate change, the role of coral epigenetics (specifically, gene body methylation, GBM) in coral acclimatization warrants investigation. The evidence is currently conflicting. In diverse animal phyla, the baseline GBM level is associated with gene function: continuously expressed "housekeeping" genes are typically highly methylated, while inducible context-dependent genes have low or no methylation at all. Some authors report an association between GBM and the environment and interpret this observation as evidence of the GBM's role in acclimatization. Yet, others argue that the correlation between GBM change and gene expression change is typically absent or negligible. Here, we used the reef-building coral, Acropora millepora, to test whether environmentally driven changes in GBM are associated with a gene's ability to respond to environmental changes (plasticity) rather than expression level. We analyzed two cases of modified gene expression plasticity observed in a 3-week-long heat acclimatization experiment. The first one was a group of heat-induced genes that failed to revert their expression after the coral was translocated back to the control tank. The second case involved genes that changed the magnitude of their response to the daily temperature fluctuations over the course of the experiment. In both cases, we found negligible or no association with GBM change. We conclude that although both gene expression plasticity and GBM can change during acclimatization, there is no direct association between the two. This adds to the increasing volume of evidence that the function of GBM in invertebrates is unrelated to acclimatization on physiological timescales.

A new isolate cold-adapted Ankistrodesmus sp. OR119838: influence of light, temperature, and nitrogen concentration on growth characteristics and biochemical composition using the two-stage cultivation strategy.

Natural-based chemicals from microalgae such as lipids and pigments are the interests in industries and the bioeconomy. Cold-adapted Ankistrodesmus sp. OR119838, an isolated strain from Cheshmeh-Sabz Lake in northeastern Iran, was cultivated using a two-stage culture strategy under different environmental conditions. With doubling the nitrate concentration at the vegetative stage (170mg/L) and increasing the light intensity (180µmol photons/m2/s) the highest specific growth rate (0.61 ± 0.02 per day) and biomass productivity (121.1 ± 7.2 mg/L/day) were observed at 25°C. In the optimal growth condition Chl a and Chl b contents of Ankistrodesmus sp. OR119838 reached the highest amount (11.07 ± 0.14 and 11.23 ± 0.29 µg/mL, respectively) at 25°C. While carotenoid content correlated negatively with optimum biomass productivity (-0.708) and had the best value (12.23 ± 0.29µg/mL) in nitrogen deficiency (42 mg/L) and intense light conditions (180µmol photons/m2/s) at 15°C. Lipid content was increased with declined nitrate concentration (42mg/L), high light intensity, and 180µmol photons/m2/s at 25°C. The highest percentage of polyunsaturated fatty acids (71.94%) and α-linolenic acid (57.73 ± 6.63%) was observed in conditions with 170mg/L nitrate concentration and low light intensity (40µmol photons/m2/ s) at the low temperature (15°C). While saturated fatty acids content (43.27%) and palmitic acid reached the highest amount under 40µmol photons/m2/s, 42mg/L nitrate at 25°C (35.02 ± 5.33%). Biomass productivity of Ankistrodesmus sp. OR119838, as a cold-adapted strain, decreased by only 8.2% with a 10-degree decline in temperature. Therefore, this strain has good potential to grow in open ponds by tolerating the daily temperature fluctuations.

Development of a regional climate change model for Aedes vigilax and Aedes camptorhynchus (Diptera: Culicidae) in Perth, Western Australia.

Mosquito-borne disease is a significant public health issue and within Australia Ross River virus (RRV) is the most reported. This study combines a mechanistic model of mosquito development for two mosquito vectors; Aedes vigilax and Aedes camptorhynchus, with climate projections from three climate models for two Representative Concentration Pathways (RCPs), to examine the possible effects of climate change and sea-level rise on a temperate tidal saltmarsh habitat in Perth, Western Australia. The projections were run under no accretion and accretion scenarios using a known mosquito habitat as a case study. This improves our understanding of the possible implications of sea-level rise, accretion and climate change for mosquito control programmes for similar habitats across temperate tidal areas found in Southwest Western Australia. The output of the model indicate that the proportion of the year mosquitoes are active increases. Population abundances of the two Aedes species increase markedly. The main drivers of changes in mosquito population abundances are increases in the frequency of inundation of the tidal wetland and size of the area inundated, increased minimum water temperature, and decreased daily temperature fluctuations as water depth increases due to sea level changes, particularly under the model with no accretion. The effects on mosquito populations are more marked for RCP 8.5 when compared to RCP 4.5 but were consistent among the three climate change models. The results indicate that Ae. vigilax is likely to be the most abundant species in 2030 and 2050, but that by 2070 Aedes camptorhynchus may become the more abundant species. This increase would put considerable pressure on existing mosquito control programmes and increase the risk of mosquito-borne disease and nuisance biting to the local community, and planning to mitigate these potential impacts should commence now.

Experimental and computational comparison of freeze-thaw-induced pressure generation in red and sugar maple.

Sap exudation is the process whereby trees such as sugar (Acer saccharum Marsh.) and red maple (Acer rubrum L.) generate unusually high positive stem pressure in response to repeated cycles of freeze and thaw. This elevated xylem pressure permits the sap to be harvested over a period of several weeks and hence is a major factor in the viability of the maple syrup industry. The extensive literature on sap exudation documents competing hypotheses regarding the physical and biological mechanisms that drive positive pressure generation in maple, but to date, relatively little effort has been expended on devising mathematical models for the exudation process. In this paper, we utilize an existing model of Graf etal. (J Roy Soc Interface 12:20150665, 2015) that describes heat and mass transport within the multiphase gas-liquid-ice mixture in the porous xylem tissue. The model captures the inherent multiscale nature of xylem transport by including phase change and osmotic transport in wood cells on the microscale, which is coupled to heat transport through the tree stem on the macroscale. A parametric study based on simulations with synthetic temperature data identifies the model parameters that have greatest impact on stem pressure build-up. Measured daily temperature fluctuations are then used as model inputs and the resulting simulated pressures are compared directly with experimental measurements taken from mature red and sugar maple stems during the sap harvest season. The results demonstrate that our multiscale freeze-thaw model reproduces realistic exudation behavior, thereby providing novel insights into the specific physical mechanisms that dominate positive pressure generation in maple trees.

Successive responses of three coral holobiont components (coral hosts, symbiotic algae, and bacteria) to daily temperature fluctuations

Corals and their associated microbiota form a “holobiont,” which includes symbiotic algae and other associated microbiota dominated by bacteria. The composition of holobiont is influenced by various environmental factors, such as increasing sea water temperatures. Previous studies of the effects of temperature changes on coral physiology and associated bacterial communities have been conducted based on stable water temperatures set by mean temperatures, or by slowly increasing/decreasing temperatures. However, the daily temperature fluctuations that corals experience in nature are not stable. The current understanding of the effects of large daily temperature fluctuations on coral and associated bacterial community dynamics is limited. Hence, we conducted a four-week tank experiment using different large daily temperature fluctuations (±5 °C and ±7 °C) accompanied by continuous warming conditions (26 °C to 29 °C) to investigate the effects on two common reef-building corals, Stylophora pistillata and Pocillopora acuta. During the experiment, the activity of coral host catalase and superoxide dismutase were measured, the photosynthetic ability of symbiotic algae was recorded, and the variation in bacterial communities was analyzed using the V6-V8 region of 16S rDNA. According to the results, different parts of the holobionts of two coral species exhibited varying response rates to the continuous warming conditions and diurnal temperature fluctuations. Additionally, it was found that diurnal temperature fluctuations may mitigate the heat stress on the host and reduce the changes in bacterial response to warming. Therefore, it is suggested that the holobionts of different coral species may adopt different adaptation and survival strategies in response to diurnal temperature fluctuations and warming. Finally, based on the response of these two coral species under the conditions of diurnal temperature fluctuations and continuous warming, Acinetobacter and Rhodobacteraceae were identified as potential indicator coral-associated bacteria. This is the first study to investigate the tripartite dynamic response of coral, symbiotic algae and bacteria to daily temperature fluctuations.

Factors and mechanisms influencing seasonal disorders in pig reproduction

The problem of unsatisfactory reproductive results in pigs is visible in a significant percentage of herds, especially during summer months and early autumn (seasonal summer infertility). This is reflected mainly in the reduced percentage of sows entering estrus after weaning and the effectiveness of mating/insemination. The consequence is a significantly lower number of births in November, December and sometimes even in January, compared to other seasons. There are many causes of seasonal summer infertility. The first things mentioned are usually the length of the light day and the high temperature in the pigs environment. An important reason that is not often discussed is the daily temperature fluctuations which usually occur at the end of summer and the beginning of autumn. Persistent unfavorable conditions are responsible for long-term stress. Hormonal disorders related to stress, leading to reproductive disorders, result from connections taking place in the hypothalamus between the hypothalamus-pituitary-gonadal axis (HPG), which regulates, among others, the reproductive functions of the ovaries, and the hypothalamus – pituitary – adrenal axis – HPA which governs organism reaction to stress. Under stressful conditions, glucocorticoids (cortisol, corticosterone) secreted in large amounts by the adrenal glands, as well as adrenaline, norepinephrine and, in small amounts, dopamine, may inhibit reproductive functions at the level of the hypothalamus, reducing the secretion of GnRH. At the same time, by reaching the pituitary gland, these hormones limit the sensitivity of the cells of this endocrine gland to GnRH. As a consequence, the maturation of follicles slows down, the number of ovulating and rupturing follicles decreases, and the secretion of estrogen is reduced. The consequence is the absence of heat or, more often, the so-called “silent heat”. Another problem is the uneven maturation of the follicles, which leads to a delayed appearance of estrus and its longer duration: 3-4 days. The final effect of these is a decrease in the rate of females presenting heat after weaning of piglets, a deterioration in the mating/insemination success rate, an increase in the rate of early abortions and percentage of litters with a small number of piglets in a litter. The summary stated that despite the identification of various seasonal causes of reproductive disorders in pigs, depending on both sows and boars, and the availability of various “tools” to reduce phenomenon of seasonal infertility, the presented problem has not been solved in a large percentage of swine farms. Its intensity varies and depends primarily on awareness, knowledge of ways to eliminate unfavorable conditions and determination in this regard. The first step, as always, is to objectively assess the situation. The assessment can be made through a detailed analysis of production data.

Ingestion and respiration rates of a common coastal mysid respond differently to diurnal temperature fluctuation

AbstractAnimals face strong environmental variability even on short time scales particularly in shallow coastal habitats, forcing them to permanently adjust their metabolism. Respiration rates of aquatic ectotherms are directly influenced by water temperature, whereas ingestion rates might additionally be influenced by behavior. We aim to understand how respiration and ingestion rates of an aquatic invertebrate respond to changing temperature during a diurnal thermal fluctuation cycle and how both processes are related. We studied the benthopelagic mysid Neomysis integer as an important food web component of coastal ecosystems. Mysids were collected at the southern Baltic Sea coast and exposed in the laboratory to either constant temperature of 15°C or daily temperature fluctuation of 15 ± 5°C. Short‐term (1–2 h) respiration and ingestion rates were measured at four equidistant time points within 24 h and did not differ among time points at constant temperature, but differed among time points in the fluctuating treatment. Respiration was highest at the thermal maximum and lowest at the thermal minimum. Ingestion rates showed the opposite pattern under fluctuation, likely due to differences in underlying thermal performance curves. When temperature transited the average, the direction of temperature change influenced the animals' response in respiration and ingestion rates differently. Our results suggest that respiration is not only instantaneously affected by temperature, but also influenced by the previously experienced direction of thermal change. Our experiment, using an important non‐model organism, delivered new insights on the relationship between the crucial organismal processes ingestion and respiration under thermal variability.

Characterisation of the COMFORTBOARD gypsum board for thermal energy storage in buildings

Currently, the construction sector contributes considerably to the total energy consumption and greenhouse gas emissions into the atmosphere. Thermal energy storage (TES) systems are alternatives to increase the thermal inertia of buildings, aiming to use less energy, improve thermal comfort and reduce temperature fluctuations of interior spaces. One of the possible applications in buildings is to increase their thermal mass by impregnating phase change materials (PCM) in porous construction materials, e.g., gypsum boards. In this investigation, a commercial gypsum board impregnated with PCM (Knauf Comfortboard – BASF) was investigated by carrying out a structural and thermal characterisation. The thermal response obtained agrees with the product's technical data sheet provided by the supplier. The results of the thermal characterisation show that the inclusion of PCM in the gypsum board decreased the U-value by 2 % compared to the control sample (no PCM), increased the heat storage capacity by around 45 %, improved the thermal dynamic characteristics of the material by decreasing the thermal stability coefficient from 0.92 to 0.76 and increasing the thermal lag from 0.27 to 0.49 h. Our results sustain the potential application of commercial gypsum boards with PCM under environmental conditions across a wide range of daily temperature fluctuations (e.g., The North of Chile).

Micro-ridge-furrow soil moisture regulation technology improves seedling quality and yield of winter rapeseed

Rapeseed (Brassica napus L.) is an important oil crop worldwide, and the Yangtze River Basin (YRB) region is one of the most vital rapeseeds producing areas in China. However, the uneven distribution of annual precipitation during the rapeseed seedling stage in this region often leads to droughts and waterlogging, resulting in declined rapeseed seedling quality and yield. Therefore, this study aimed to assess the impact of micro-ridge-furrow planting (MR) and conventional flat cropping planting (FC) under straw returning on rapeseed seedling growth and yield during two growing seasons: wet year (WY) and dry year (DY). In MR planting, rapeseed was sown either on the ridge surface (RS) or in the ridge furrow (RF). We found that MR planting had stronger regulation of soil temperature and humidity compared to FC. The average soil volume water content in RS was 19.2 % lower than FC, while in RF, it was 9.0 % higher than FC. Under MR planting, the daily temperature fluctuations in RF were smaller than in FC, whereas in RS, they were larger than in FC. Through the adjustment of temperature and humidity, MR increased the activities of β-glucosidase (β-Glu) and cellulose disaccharide hydrolase (CBH) in the soil, thereby accelerating rice straw decomposition. Importantly, MR led to improved root growth, seedling quality, precipitation water use efficiency (WUEP), and yield of rapeseed during both the WY and DY seasons. Notably, root morphological traits were significantly altered under straw returning (RT) in MR, particularly with an 11.0 % increase in root surface area, which showed a significant correlation with the indoleacetic acid and jasmonic acid contents in the root system. Furthermore, RT increased antioxidant enzymes activity in rapeseed roots. The H2O2 and ∙OH contents in MR were lower than in FC, indicating that the roots of MR were capable of self-protection and reducing the accumulation of superoxide radicals and peroxides by adapting actively to the soil water environment under straw returning. The yield and WUEP of MR were higher by 11.9 % and 21.0 %, respectively, compared to FC. In conclusion, MR planting has the potential to enhance seedling quality and increase rapeseed yield when combined with rice straw returning. This finding provides technical support for realizing the full and strong seedling establishment and improving the cultivation of direct-seeded rapeseed in the YRB region.

Impact of Positioning Phase Change Materials on Thermal Performance of Buildings in Cold Climates

The building envelope, an essential component of any building, plays a critical role in meeting energy efficiency and thermal comfort requirements. Incorporating phase change materials (PCM) into the building envelope can offer an opportunity to minimize energy usage and enhance thermal comfort by offsetting daily temperature fluctuations. However, the optimal performance of PCM is contingent on the material’s placement and thickness within the building envelope. Therefore, this study investigated the effects of positioning and thickness of PCM on thermal comfort and heating loads in a lightweight timber building in Trondheim, Norway. Four scenarios were considered based on the positioning of the PCM layer in the exterior wall and roof. Using IDA ICE, parametric simulations were conducted for various PCM wallboard positions and thicknesses in the exterior wall and roof. In Nordic climates, adding PCM reduces the risk of annual overheating. The findings of this study showed that installing 75mm of PCM wallboard in the exterior wall’s inner layer reduced the annual heating load by 2.3%. Compared to the base case scenario, increasing PCM thickness reduced zonal maximum indoor air temperatures by up to 6.2°C. This study underscored the importance of carefully considering the placement and thickness of PCM in building envelopes for optimal performance.

Potential of processed barnacles shell as soil conditioner using mung bean plants (Vigna radiata L.) growth

Barnacles as periphyte animals often found clinging on the ship’s hull, being unutilized waste that presents in such abundance. Calcium carbonate in barnacle shells would increase the chance of degrading microbial community survival in the soil, indirectly increasing soil fertility. The processing of barnacle shells to be used as a calcium carbonate supplement involves harvesting, drying, powdering, sterilizing, and mixing it to the soil. We want to observe comparison of the performance of control group (K), processed barnacle shells (T), industrial 16-16-16 NPK (Nitrogen, Phosphate, Potassium) fertilizer (P), and the combination of processed barnacle shell with 16-16-16 NPK fertilizer (TP) supplementation to the soil as planting media by the daily temperature, pH, and moisture fluctuation, besides the measurement of the growth of mung bean plant, Vigna radiata L. (VIMA 5 variant) regarding their application to the soil. The growth of V. radiata L. is measured by epicotyl length, number of leaves, and total wet mass increase of each plant individual. Vigna radiata L. in the control group shows the best growth measured by parameters listed above. However, ANOVA analysis shows statistical significance on the correlation of types of soil treatment (K, T, P, or TP supplementation) to daily moisture fluctuation.

Thermal and Humidity Performance Test of Rammed-Earth Dwellings in Northwest Sichuan during Summer and Winter.

Rammed-earth dwellings have a long history in the construction field. It is a natural material that is both green and environmentally friendly. In recent years, the advantages of rammed earth, such as environmental protection, low cost, and recyclability, have attracted considerable attention. In this study, the thermal and humidity physical properties of rammed-earth materials in the northwest Sichuan region, the variation laws of thermal physical parameters, such as the thermal conductivity of rammed-earth under different moisture content conditions, and isothermal moisture absorption and desorption curves were investigated. The results indicated that the thermal physical parameters of the rammed earth measured in the experiment increased with an increase in moisture content, and its moisture absorption performance was better than the moisture release performance in the range of 11.31-97.3% relative humidity. The experimental site, Mianyang City, Sichuan Province, is a subtropical monsoon humid climate zone characterized by warm winters and hot summers with four distinct seasons. In this study, we investigated the hygrothermal coupling transfer of walls, as well as the indoor temperature and humidity changes in new rammed-earth buildings during summer and winter climates. During the test period, the maximum indoor temperature in summer was 35.08 °C, the minimum temperature was 33.76 °C, and the average daily temperature fluctuation was 3.62 °C. In winter, the maximum indoor temperature was 8.59 °C, the minimum temperature was 6.18 °C, and the average daily temperature fluctuation was 1.21 °C. An analysis was performed on the thermal insulation performance of rammed-earth buildings in an extremely high-temperature climate during summer, thermal insulation performance, the thermal-buffering capacity of walls in a low-temperature and high-humidity climate during winter, and thermal and humidity regulation of indoor environments provided by walls during summer and winter. The results showed that the rammed-earth buildings exhibited warmth in winter, coolness in summer, and a more stable and comfortable indoor environment.

Assessment of the Vulnerability of Riverine Cities and Their Coping Capacity against Floods (Case Study: Ahvaz Metropolis)

Based on global statistics, floods rank the first among natural disasters that severely disrupt human life, property, and the environment. Iran, as one of the flood-prone countries, is located in southwestern Asia. The geographical elevation, maritime influences, seasonal winds, and proximity to mountain ranges or deserts play a significant role in its daily and seasonal temperature fluctuations, as well as its precipitation patterns and types. According to official statistics in Iran, among climate-related hazards, some 70% of the annual funds of the Plan for Reducing the Effects of Natural Disasters have been spent on compensation for damages from floods. Yet, what augments the importance of floods and their damages is the fact that human and urban centers have been located in flood-prone areas. Therefore, considering the dense populations and financial capitals in such areas, it is necessary to assess the vulnerability of urban floods, especially in big cities like Ahvaz. This metropolis, as the capital of Khuzestan province, is located in the marshy plains with a population of over one million people. It is traversed by the country’s most water-rich river, the Karun. The aim of this study is to assess the vulnerability of Ahvaz from flood as a natural hazard and its coping capacity. The methodology of the study is descriptive-analytical and is based on its practical purpose. Fuzzy Hierarchy Model (Fuzzy Analytic Hierarchy Process) has been used for the spatial analysis of vulnerability and the capacity to deal with floods. In summary, the findings are as follows: (a) Considering the floods that have occurred in the past six decades and comparing the affected areas with the results of this research in terms of highly vulnerable areas in the central part of the city, the model used has shown high efficiency in determining the vulnerability caused by urban flooding. (b) As far as vulnerability is concerned, location and physical–environmental conditions stimulate and reinforce other factors which are influential in determining the level of vulnerability. (c) Encroachment on river boundaries, especially limiting the river width, leads to a reduction in flood capacity and an increase in vulnerability in those areas. (d) The vulnerability level of Ahvaz to flooding, based on area, falls within five categories of vulnerability spectrum as follows: Very High 4.6%, High 8.7%, Moderate 13.4%, Low 15.2%, and Very Low 58%.

Higher temperature and daily fluctuations aggravate clothianidin toxicity towards Limnodrilus hoffmeisteri

In nature, aquatic organisms may suffer from chemical pollution, together with thermal stress resulted from global warming. However, limited information is available on the combined effects of pesticide with climate change on aquatic organisms. In this study, the acute toxicity of clothianidin to Limnodrilus hoffmeisteri as well as its effect on the induction of oxidative stress under both constant temperature and daily temperature fluctuation (DTF) regimes was investigated. Results showed that clothianidin exhibited the minimal toxicity to L. hoffmeisteri at 25 °C, which was magnified by both increased or decreased temperatures and 10 °C DTF. At different temperatures (15 °C, 25 °C and 35 °C), clothianidin exposure led to the elevated reactive oxygen species (ROS) levels and activated the antioxidant enzymes to resist against the oxidative stress. However, the antioxidant response induced by clothianidin was overwhelmed at high temperature as evidenced by decreased glutathione (GSH) content. Significant elevation of catalase (CAT) and peroxidase (POD) activities but depletion of GSH was also observed in worms treated with clothianidin under DTF after 24 h. The results indicated that high temperature and DTF could aggravate the clothianidin-induced oxidative stress. Moreover, the critical thermal maximum (CTmax) of the worms decreased with the increasing clothianidin concentrations, suggesting that exposure to clothianidin could reduce the heat tolerance of L. hoffmeisteri. Our work highlights the crucial importance to integrate temperature changes into risk assessment of pesticides under global warming.

Soil Dynamics and Crop Yield Modeling Using the MONICA Crop Simulation Model and Time Series Forecasting Methods

Crop simulation models are an important tool for assessing agroecosystem performance and the impact of agrotechnologies on soil cover condition. However, the high uncertainty and labor intensiveness of long-term weather forecasting limits the applicability of such models. A possible solution may be to use time series forecasting models (SARIMAX and Prophet) and artificial neural-network-based technologies (Neural Prophet). This work compares the applicability of these methods for modeling soil condition dynamics and agroecosystem performance using the MONICA simulation model for Voronic Chernozems in the Kursk region of Russia. The goal is to determine which weather indicators are most important for the yield forecast and to choose the most appropriate methods for forecasting weather scenarios for agricultural modeling. Crop rotation of soybean and sugar beet was simulated, with agricultural techniques and fertilizer usage considered as factors. We demonstrated the high sensitivity of aboveground biomass production and soil moisture dynamics to daily temperature fluctuations and precipitation during the vegetation period. The dynamics of the leaf area index and nitrate content showed less sensitivity to the daily fluctuations of temperature and precipitation. Among the proposed forecasting methods, both SARIMAX and the Neural Prophet algorithm demonstrated the ability to forecast weather to model the dynamics of crop and soil conditions with the highest degree of approximation to actual observations. For the dynamic of the crop yield of soybean, the SARIMAX model exhibited the most favorable coefficient of determination, R2, while for sugar beet, the Neural Prophet model achieved superior R2 levels of 0.99 and 0.98, respectively.

Investigation of Temperature Effects into Long-Span Bridges via Hybrid Sensing and Supervised Regression Models

Temperature is an important environmental factor for long-span bridges because it induces thermal loads on structural components that cause considerable displacements, stresses, and structural damage. Hence, it is critical to acquire up-to-date information on the status, sustainability, and serviceability of long-span bridges under daily and seasonal temperature fluctuations. This paper intends to investigate the effects of temperature variability on structural displacements obtained from remote sensing and represent their relationship using supervised regression models. In contrast to other studies in this field, one of the contributions of this paper is to leverage hybrid sensing as a combination of contact and non-contact sensors for measuring temperature data and structural responses. Apart from temperature, other unmeasured environmental and operational conditions may affect structural displacements of long-span bridges separately or simultaneously. For this issue, this paper incorporates a correlation analysis between the measured predictor (temperature) and response (displacement) data using a linear correlation measure, the Pearson correlation coefficient, as well as nonlinear correlation measures, namely the Spearman and Kendall correlation coefficients and the maximal information criterion, to determine whether the measured environmental factor is dominant or other unmeasured conditions affect structural responses. Finally, three supervised regression techniques based on a linear regression model, Gaussian process regression, and support vector regression are considered to model the relationship between temperature and structural displacements and to conduct the prediction process. Temperature and limited displacement data related to three long-span bridges are used to demonstrate the results of this research. The aim of this research is to assess and realize whether contact-based sensors installed in a bridge structure for measuring environmental and/or operational factors are sufficient or if it is necessary to consider further sensors and investigations.