Gradual Increase In Temperature Research Articles

Marine heat waves drive bleaching and necrosis of temperate sponges

Marine heat waves (MHWs) are extended periods of excessively warm water1 that are increasing in frequency, duration, intensity, and impact, and they likely represent a greater threat to marine ecosystems than the more gradual increases in sea surface temperature.2,3,4 Sponges are major and important components of global benthic marine communities,5,6,7 with earlier studies identifying tropical sponges as potential climate change "winners."8,9,10,11 In contrast, cold-water sponges may be less tolerant to predicted ocean warming and concurrent MHWs. Here, we report how a series of unprecedented MHWs in New Zealand have impacted millions of sponges at a spatial scale far greater than previously reported anywhere in the world. We reported sponge tissue necrosis12 and bleaching (symbiont loss/dysfunction),13 which have been previously associated with temperature stress,6,12,14 for three common sponge species across multiple biogeographical regions, with the severity of impact being correlated with MHW intensity. Given the ecological importance of sponges,15 their loss from these rocky temperate reefs will likely have important ecosystem-level consequences.

Mathematical modeling of drinking water availability in Kharkiv region (Ukraine) at different dynamics of global climate warming

Water purity and availability determines health and life quality of humans, biodiversity and existence of plants and animals. The results of global climate change have been registered all over the world as progressive warming with fast heat waves, accelerated glacier ice melting, variations in the global ocean streams and heat balance, droughts and lack of drinking water, damage to plants and animals. Mathematical modeling of the water exchange in local ecosystems is a very important constituent of detailed analysis of different scenarios of water availability at various trends in the weather change.
 The work is aimed at mathematical modelling of water balance in an urban ecosystem accounting for global climate changes. A brief review of the models is presented, and a synthetic model for the water balance on the urban territory of Kharkiv city (Ukraine) based on the statistical dependencies, compartmental system dynamics approach and hydrological equation with probabilistic description of the input parameters is developed. The monthly and year averaged temperature and precipitation curves, time series on downpours, droughts and storms over the Kharkiv region and Kharkiv city during 1908−2012 years were collected from the open databases and analyzed. Gradual increase in the annual temperature was confirmed.
 Different scenarios of the regional development (population growth and industry development with increased water demands) and weather changes were tested, and availability of water has been estimated. It was established by numerical simulations, the water insufficiency in the region in 2040 could reach 10−17 % if the mean annual air temperature increases in 0.5−2.5 °T. This will cause damage for plants, animals, and human health. The obtained results are important for decision making by official planning authorities and regional administration

Scientists' warning on climate change and insects

AbstractClimate warming is considered to be among the most serious of anthropogenic stresses to the environment, because it not only has direct effects on biodiversity, but it also exacerbates the harmful effects of other human‐mediated threats. The associated consequences are potentially severe, particularly in terms of threats to species preservation, as well as in the preservation of an array of ecosystem services provided by biodiversity. Among the most affected groups of animals are insects—central components of many ecosystems—for which climate change has pervasive effects from individuals to communities. In this contribution to the scientists' warning series, we summarize the effect of the gradual global surface temperature increase on insects, in terms of physiology, behavior, phenology, distribution, and species interactions, as well as the effect of increased frequency and duration of extreme events such as hot and cold spells, fires, droughts, and floods on these parameters. We warn that, if no action is taken to better understand and reduce the action of climate change on insects, we will drastically reduce our ability to build a sustainable future based on healthy, functional ecosystems. We discuss perspectives on relevant ways to conserve insects in the face of climate change, and we offer several key recommendations on management approaches that can be adopted, on policies that should be pursued, and on the involvement of the general public in the protection effort.

High temperature induced metabolic reprogramming and lipid remodeling in a high-altitude fish species, Triplophysa bleekeri

The effect of thermal changes on the physiology and behavior of fish is a major research focus in the face of ongoing global warming. There is little information about the effects of temperature increase on fish in the wild. However, the consequences of temperature increase on fish in controlled laboratory conditions can provide insights into what can be expected in the wild. Triplophysa bleekeri, a high-plateau fish, exhibits high sensitivity to high temperatures, suggesting it to be a good model to investigate the impact of temperature increase on fish. In this study, we analyzed the effect of gradual temperature increase on transcriptional and metabolic levels of T. bleekeri subjected to a gradual temperature change of 0.5°C/day until temperatures of 10°C, 13°C, 16°C, and 19°C were reached. Transcriptomics results of the liver, gut, spleen, and trunk kidney showed that metabolic pathways are widely involved in the response to increased temperatures in T. bleekeri. Lipidomics results further indicated that the lipid composition was altered by increased temperatures, and three lipids (PC 14:0e/22:1, PC 18:0e/22:5, and TAG 14:3-21:2-21:2) were identified as potential biomarkers of heat stress in T. bleekeri. Moreover, a decline in unsaturated fatty acid levels was observed in T. bleekeri under high temperatures. These results suggest that high temperatures modify the metabolomic pathways. Overall, our results help improve the understanding of physiological responses in fish to increased temperatures, and provide valuable information predicting the consequences of global warming on fish.

Determination of dynamic deformation behavior of Golden Delicious apple using finite element method and its validation by scanning electron microscopy

Apple fruit is affected by operations such as harvesting, packing, grading, storage, and transportation on the way from the garden to the sales centers. During these stages, the products are subjected to several static and dynamic loads applied to each product, damaging them. The aim of this study was to determine the dynamic deformation behavior using finite element simulation and to investigate the surface temperature changes of Golden Delicious apple cultivar due to impact loads. For this purpose, the physical, mechanical and rheological properties of the internal components of apples were determined in three parts: skin, flesh and core. A viscoelastic material model was defined for more accurate simulation. Scanning electron microscope is used to measure the volume of damage and a thermal camera is used to measure the surface temperature of the product. To collect valid data in the dynamic loading section, the pendulum impact test was performed in the form of a factorial design. In this test, the independent variables included impact levels at 3 levels, product temperature at 2 levels and product radius of curvature at 2 levels, and dependent variables included bruising volume and surface temperature difference. The simulation results showed that the difference in bruise volume in the force-time and velocity-time methods with the bruise volume in the experimental test was 14.12% and 18.53%, respectively, and the maximum difference in reaction force was 9.36% and 15.97%. Therefore, in dynamic simulation based on pendulum impact test results, the use of force-time data offers better results than velocity-time data. The results of surface temperature measurements showed that with a gradual increase in apple temperature, the surface temperature of the bruised area is lower than the temperature of the healthy area. The highest surface temperature difference was observed in 30 minutes after impact and in the third impact level (33 N) equivalent (0.4 °C). Also, the results of the experimental pendulum impact test showed that all three factors of impact level, product temperature and radius of curvature had significant differences in bruising volume. Thus, the volume of bruising is directly related to the impact surface and the radius of curvature and inversely related to the apple temperature.

Localized photothermal heating of phosphate-incorporated iron oxide nanosheets enables greatly enhanced water splitting electrocatalysis

Introducing an external energy field into water electrolysis is considered as an innovative strategy to improve electrocatalysis for water splitting. However, rationally modulating these external energy fields to synergize electrocatalytic processes remains a great challenge. Herein, phosphate-incorporated iron oxide nanosheet arrays (P-FeOx/IF) are constructed as multifunctional photothermal-electrocatalytic electrodes for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The as-prepared P-FeOx/IF exhibits excellent photothermal conversion performance and enables in-situ surface self-heating under near-infrared (NIR) light irradiation, resulting in a gradual increase in local temperature on the electrode surface. Impressively, the photothermal P-FeOx/IF electrode exposed to NIR light irradiation shows significantly improved electrocatalytic performances with relatively low overpotentials for OER (η10: 280 mV) and HER (η10: 104 mV) to deliver a current density of 10 mA cm−2. Furthermore, a two-electrode system using photothermal P-FeOx/IF as anode achieves a low cell voltage of 1.685 V. This study provides a new avenue for developing high-performance electrocatalysts incorporating photothermal effects.

Self-lubricating design strategy for thermally sprayed ceramic coatings by in-situ synthesis of carbon spheres

Conventional thermally sprayed ceramic self-lubricating coatings have significantly decreased their in-service stability and crack damage resistance due to their intrinsic brittleness and reduced mechanical properties resulting from tribological design. Herein, we successfully prepared a series of yttria stabilization zirconia (YSZ)-carbon coatings by combining in-situ carbon synthesis with thermal spraying technology. The influence of hydrothermal reaction temperature on the microstructure, mechanical properties, and tribological behavior of composite coatings has been investigated. Results indicate that carbon spheres grow in-situ within the inherent defects of YSZ coatings. With the gradual increase in reaction temperature, the size, degree of crystallinity, and graphitization of synthetic carbon spheres increase continuously. In addition, the composite coating exhibits outstanding mechanical properties, with the hardness and cohesive strength of the coating improved by 18.2 % and 62.3 %, respectively. Moreover, the composite coating prepared at 280 °C has the best tribological properties: the coefficient of friction is reduced by 77.1 % to 0.22, and its wear resistance property has been significantly improved, with the wear rate dropping from 6.35 × 10−4 to 8.75 × 10−7 mm3 N−1·m−1. A well-covered lubricating film composed of carbon, YSZ, and alumina nanoparticles contributes to the improved tribological performance.

Distribution and spatio-temporal variation of temperature and precipitation in the Sierra de Otontepec Ecological Reserve, Veracruz, Mexico through GIS modelling

Sierra de Otontepec Ecological Reserve is an isolated mountain in the Coastal Plain of Gulf of Mexico with great scientific importance. However, it lacks climatological information to support the studies of the ecosystems that have been carried out in recent years. Through GIS modelling its climatology was characterized, and climate variability scenarios were created for the period 1981-2010. From temperature and precipitation data recorded in situ, vertical gradients of both variables were obtained in relation to the orography of the zone. The records were correlated with data from nearby weather stations so that by using a DEM it was possible to obtain raster layers with a resolution of 15 m per pixel for temperature, in the summer and winter seasons; and for precipitation, in the rainy and dry seasons; the annual value was also calculated for both variables. The climatic variability detected in the zone indicates a gradual increase in air temperature over time and a spatial variation in the distribution of precipitation. The spatial resolution of the modelling is precisely adjusted to the relief of the mountain, allowing the flora and fauna elements found within each pixel to be analysed with a good level of detail. This work represents the most viable and effective alternative to estimate temperature and precipitation values in mountain systems lacking climatological stations; demonstrating that beyond providing climate information, which is increasingly necessary for ecosystems, it is possible to model their spatio-temporal dynamics to better understand the complex climate variability of our days.

Climate Change Impact on the Habitat Suitability of Pseudotsuga menziesii Mirb. Franco in Mexico: An Approach for Its Conservation

One of the conifers that survived after the last glaciation is the Pseudotsuga menziesii (Mirb.) Franco. Due to the gradual increase in temperature, this species was forced to move from the south to the north and to higher elevation, causing a fragmented and intermittent distribution in Mexico. The main objective of this study was to model and identify suitable areas for the future conservation of the P. menziesii in Mexico. The specific objectives of this research were: (i) to model the habitat suitability of P. menziesii in Mexico, (ii) to identify the most relevant environmental variables based on its current and future habitat suitability (2030, 2050, 2070 and 2090) and (iii) to suggest areas for the conservation of the species in Mexico. Records were compiled from different national and international sources. Climate and topographic variables were used. With MaxEnt software version 3.4.3 (Phillips, New York, NY, USA) 100 distribution models were obtained, where the model showed an area under the curve of 0.905 for training and 0.906 for validation and partial ROC of 1.95 and Z reliable (p < 0.01), with TSS values > 0.80. The current area of the P. menziesii was 31,580.65 km2. The most important variables in the current and future distribution were maximum temperature of the hottest month, precipitation of the coldest trimester and average temperature of the coldest trimester. The percentage of permanence (resilience) for the 2030, 2050, 2070 and 2090 climate horizons was 49.79%, 25.14%, 17.45% and 16.46%, respectively, for the SSP 245 scenario. On the other hand, for the SSP 585 scenario and the analyzed horizons, the percentage resilience in areas of suitable habitat zones was 41.45%, 27.42%, 9.82% and 2.89%.

Dielectric constant of disordered phases of the smallest monoalcohols: Evidence for the hindered plastic crystal phase

With gradual temperature increase in premelting regions of solid phase of methanol and high pressure phase of ethanol, and using novel procedure of separation of electrode polarization effects, we are able to register the contribution of relaxation process to low-frequency dielectric constant. This contribution is about half the liquid’s dielectric constant near temperature of solidification, and is almost an order of magnitude higher than reported earlier for ambient pressure phase of methanol. As opposed to dielectric constant of water at ambient pressure, which does not change much during crystallization, our finding indicates the hindrance of molecule rotation in orientationally disordered phases of monoalcohols. Similar dielectric responses of ambient pressure methanol and high-pressure phase of ethanol imply existence of hindered plastic crystal phase of ethanol (not observed at low pressures). We also have found some dynamic disorder in nominally fully ordered phase of these monoalcohols.

Barrier-free molecular reorientations in polyhedral water clusters

The structural stability of the weakest bonded configurations of water clusters in the form of gas hydrate cavities D and T, as well as in the form of Kelvin’s polyhedron, was tested using the local geometric optimization with the polarizable force field AMOEBA. A number of different barrier-free molecular rearrangements were observed. Most of the configurations changed their shapes, forming surface defects of the same type. But the main attention is paid to the concerted molecular reorientations leading to the proton shift along hydrogen bonds. A number of statements about the topology of the hydrogen-bonded network are rigorously proved. It is concluded that the structural stability of configurations and the features of structural transformations are basically determined by the arrangement of the homodromic hydrogen-bonded water rings. The stability of the configurations, which retained their original shape during local geometric optimization, was studied by the molecular dynamics method with a gradual increase in temperature. Some interesting effects were found. This is the stabilizing locking of the most polarized configurations, as well as very intense amplitude oscillations of the free OH group at the end of two-bond flips.

Analysis of climate changes in the forest fund lands of Boyarka Forest Research Station

The relevance of the study is conditioned upon the predicted changes in the area, as well as the significant narrowing of the zone of optimal growth of Scots pine. These forecasts are based on obtaining data on the ongoing climate changes. A constant decrease in precipitation, along with a gradual increase in temperature levels, will lead to consequences such as uncontrolled changes in ecosystems. Such a substantial change in abiotic factors caused by human activity plays a key role in the formation of forest coenoses. The main purpose of this study was to analyse the change in the average annual temperature, as well as the monthly amount of precipitation observed in the forest communities in the Separated Subdivision of the National University of Life and Environmental Sciences of Ukraine “Boyarka Forest Research Station”. The analysis is performed over decades to obtain data on the level of temperature change in relation to the previous period. This also includes a comparison of monthly precipitation for 2021 relative to 1991-2020, which is set as normal. To obtain indicators of the average annual temperature, the average value method is used, followed by calculating the value of the average annual temperature for each decade. To find the deviation in total precipitation, the method of estimating the moisture conditions according to total precipitation is used. Therewith, the value of a substantial deviation is taken at 20% relative to the precipitation rate. According to the study results, it was established that in 2001-2010 the average annual temperature changed by 0.83°C relative to the previous decade, and in 2011-2020 by 0.74°C relative to the previous period. Such dynamics indicate a gradual increase in the average annual temperature, which is reflected in the forecasts of the world community. During the estimation of moisture conditions, separate months of 2021 with a critical level of precipitation in relation to the normal period were selected. In March, the amount of precipitation was 43% of normal, in June – 32%, in September – 40%, and in October – only 4.3% of normal. The value in November was observed at 63% of the norm. Such a decrease in the amount of precipitation in relation to a gradual increase in the average annual temperature poses a threat of a decrease in the hydrological level of moisture. This leads to a decrease in the radial increment of tree stands, and a gradual shift in the growing area of Scots pine. The obtained analysis results will further be used to conduct dendrochronological studies of tree rings of Scots pine (Pinus sylvestris L.) in the tree stands of the Separated Subdivision of the National University of Life and Environmental Sciences of Ukraine “Boyarka Forest Research Station”

Optimizing plastic mulching improves the growth and increases grain yield and water use efficiency of spring maize in dryland of the Loess Plateau in China

Transparent plastic film mulching (PFM) with flat cropping cultivation has been widely applied to grow maize (Zea mays L.) in dryland agricultural production areas of the Loess Plateau in China. However, with global warming-induced gradual increase in soil temperature, film-mulched spring maize experiences premature senescence and yield loss. In this study, a new form of mulching strategy involving dual mulching of transparent plastic film with whole maize stalks in a flat plot was established to improve growth and increase water use efficiency (WUE), precipitation use efficiency (PUE), and spring maize yield. The field experiment was conducted in 20 182 019, and 2020 on a conventional flat plot without mulching (CK), a flat plot with single transparent PFM, and a flat plot of transparent film mulching with whole maize stalks (PFM+ST) in the dryland of the Loess Plateau in China, to quantify the effects of different treatments on soil hydrothermal conditions, maize phenology, plant growth dynamics, WUE, PUE, and maize yield. Results demonstrated that soil water storage (SWS) at 0–100 cm soil layer in PFM and PFM+ST were significantly superior to those in CK, but SWS did not significantly differ between PFM and PFM+ST. Soil temperature under PFM+ST at 0–25 cm soil layer decreased by 1.2 ℃ compared with that under PFM during growth, especially in early growing seasons (20–60 days after sowing [DAS]). PFM+ST extended vegetative and reproductive growth periods by 1–2 and 6–7 days compared with those in PFM, respectively. In later growth period (80–120 DAS), PFM+ST increased the root dry matter weight, SPAD, and LAI and significantly increased the aboveground dry matter accumulation. PFM+ST significantly increased the 100-kernel dry weight, grain yield, WUE, and PUE. PFM+ST had 3-year average grain yields of 10.82% and 36.48% greater than PFM and CK, respectively. The corresponding WUE and in 0–200 cm soil layer improved by 12.55% and 39.84%, and PUE improved by 10.82% and 36.48%, respectively. With global warming, applying PFM+ST cultivation practice effectively extended growth period and increased mulching spring maize yield and WUE in the study site.

Evolutionary Adaptation by Repetitive Long-Term Cultivation with Gradual Increase in Temperature for Acquiring Multi-Stress Tolerance and High Ethanol Productivity in Kluyveromyces marxianus DMKU 3-1042.

During ethanol fermentation, yeast cells are exposed to various stresses that have negative effects on cell growth, cell survival, and fermentation ability. This study, therefore, aims to develop Kluyveromyces marxianus-adapted strains that are multi-stress tolerant and to increase ethanol production at high temperatures through a novel evolutionary adaptation procedure. K. marxianus DMKU 3-1042 was subjected to repetitive long-term cultivation with gradual increases in temperature (RLCGT), which exposed cells to various stresses, including high temperatures. In each cultivation step, 1% of the previous culture was inoculated into a medium containing 1% yeast extract, 2% peptone, and 2% glucose, and cultivation was performed under a shaking condition. Four adapted strains showed increased tolerance to ethanol, furfural, hydroxymethylfurfural, and vanillin, and they also showed higher production of ethanol in a medium containing 16% glucose at high temperatures. One showed stronger ethanol tolerance. Others had similar phenotypes, including acetic acid tolerance, though genome analysis revealed that they had different mutations. Based on genome and transcriptome analyses, we discuss possible mechanisms of stress tolerance in adapted strains. All adapted strains gained a useful capacity for ethanol fermentation at high temperatures and improved tolerance to multi-stress. This suggests that RLCGT is a simple and efficient procedure for the development of robust strains.

Investigating the impact of indoor temperature on the performance of the retail commercial refrigeration system

Commercial food outlets in the UK are responsible for 3% of the UK total energy consumption, with refrigeration systems account for 29% of this total. In this paper, a validated model that simulates a commercial refrigeration system installed over 2000 sq. ft to mimic a real express store installed at the Riseholme Refrigeration Research Centre at the University of Lincoln, UK, is presented. Investigations are conducted to examine the different failures of air conditioning (AC) systems and their impacts on the indoor store temperature, and hence on the refrigeration performance and energy consumption. Three different scenarios were examined: gradual increase in store temperature caused by an AC system with reduced performance, sudden increase in store temperature caused by a drastic AC failure and fluctuations in store temperature caused by a faulty AC system. The results of the investigation for different failure scenarios of the AC system during 3 h of continual operation showed an increase in the energy consumption of the refrigeration system by 17.4% as a result of gradual AC failure, 33.6% for the sudden failure and 5.3% for the intermittent failure. It is concluded that the AC failures caused the power drawn to increase due to spending a prolonged period of time at higher temperatures than during the normal AC operation. Also, the frequency which the compressors switch on and off increases the level of wear on the compressors. Both gradual and sudden failures of the AC system show a sustained increase in temperature that leads to a greater duty cycle for the expansion valve to increase the amount of refrigerant available. It is found that the sudden failure of the AC system had the greatest impact on the system, as the temperature of the store rises quickest, the display cases are exposed to higher temperatures for a longer time; this causes the greatest demand on the system and so lead to the largest power consumption. It is notable that for all three failure types that the product temperature experiences, there are no noticeable fluctuations and they remain comfortably within the temperature boundaries between 3 and 1 °C, as the system is able to provide an adequate cooling.

Comparison of two different uses of underbody forced-air warming blankets for the prevention of hypothermia in patients undergoing arthroscopic shoulder surgery: a prospective randomized study

BackgroundForced-air warming (FAW) is an effective method of preventing inadvertent perioperative hypothermia (IPH). However, its warming effects can be influenced by the style and position of the FAW blanket. This study aimed to compare the effects of underbody FAW blankets being placed under or over patients in preventing IPH.MethodsPatients (n=100) undergoing elective arthroscopic shoulder surgery in the lateral decubitus position were randomized into either under body (UB) group or the over body (OB) group (50 per group). The body temperature of the patients was recorded from baseline to the end of anesthesia. The incidences of postoperative hypothermia and shivering were also collected.ResultsA steady decline in the body temperature was observed in both groups up to 60 minutes after the start of FAW. After 60 minutes of warming, the OB group showed a gradual increase in the body temperature. However, the body temperature still decreased in UB group until 75 minutes, with a low of 35.7℃ ± 0.4℃. Then the body temperature increased mildly and reached 35.8℃ ± 0.4℃ at 90 minutes. After 45 minutes of warming, the body temperature between the groups was significantly different (P < 0.05). The incidence of postoperative hypothermia in the UB group was significantly higher than that in the OB group (P = 0.023).ConclusionsThe body temperature was significantly better with the use of underbody FAW blankets placed over patients than with them placed under patients. However, there was not a clinically significant difference in body temperature. The incidence of postoperative hypothermia was much lower in the OB group. Therefore, placing underbody FAW blankets over patients is recommended for the prevention of IPH in patients undergoing arthroscopic shoulder surgery.Trial registrationThis single-center, prospective, RCT has completed the registration of the Chinese Clinical Trial Center at 13/1/2021 with the registration number ChiCTR2100042071. It was conducted from 14/1/2021 to 30/10/2021 as a single, blinded trial in Sichuan Provincial Orthopedic Hospital.

Gradual increase of temperature trigger metabolic and oxidative responses in plasma and body tissues in the Antarctic fish Notothenia rossii.

Antarctica is considered a thermally stable ecosystem; however, climate studies point to increases in water temperatures in this region. These thermal changes may affect the biological processes and promote metabolic changes in the adapted organisms that live in this region, rendering the animals more vulnerable to oxidative damage. This study assessed the effect of acclimation temperature on the levels of stress response markers in plasma, kidney, gill, liver, and brain tissues of Notothenia rossii subjected to gradual temperature changes of 0.5°C/day until reaching temperatures of 2, 4, 6, and 8°C. Under the effect of the 0.5°C/day acclimation rate, gill tissue showed increased glutathione-S-transferase (GST) activity; kidney tissue showed increased H+-ATPase activity. In the liver, there was also an increase in GSH. In plasma, gradual decreases in the concentrations of total proteins and globulins were observed. These responses indicate a higher production of reactive oxygen species ROS, an imbalance in energy demand, and a lack in protein synthesis. Gradual increase in temperature may cause opposite responses to the thermal shock model in N. rossii.

Effects of a warming gradient on reproductive phenology of Stipa breviflora in a desert steppe

The sensitivity of plant phenology to climate change can be used as the basis for predicting change in plant species' growth and development period as they adapt to gradual increase in atmospheric temperature. However, it is not clear how the reproductive phenology of plants will respond to a continuous increase in temperature gradient, especially when the time series has break points due to interannual change. In this experiment, the flowering phenology of Stipa breviflora, an established species in the desert steppe of Siziwang Banner in northern China, was observed from 2009 to 2019. A no warming treatment and warming treatment (1.3 °C higher than no warming) were applied. Three temperature gradients were defined: the annual average temperature of the 0–10 cm soil layer in the no warming treatment plot from 2009 to 2019 was taken as the average temperature gradient (C2, 5.63 °C ± 1.09); a higher-than-average temperature gradient (C3, 6.93 °C ± 1.34), and a lower than the average temperature gradient (C1, 4.33 °C ± 1.87). The results showed that increasing temperature was an important driving factor that advanced the flowering phenology of S. breviflora. When high temperatures exceed plants’ physiological thresholds (5.63 °C ± 1.09), plants exhibit a temporary delay. Based on a Mann-Kendall test, we found that reproductive phenology was advanced from 2009 to 2015, and delayed by a time break point from 2015 to 2018. After 2018, reproductive phenology continued to be advanced, which once again verified that reproductive phenology would not continue to be advanced in the process of climate warming, but would be temporarily delayed. Therefore, our study reveals the response strategy of S. breviflora to a continuous increase in global atmospheric temperature, and provides a theoretical basis for studying the response mechanism of the desert steppe ecosystem to climate warming.

Comparison of hydrogeochemical characteristics of thermokarst lake water in the Qinghai–Tibet Plateau under active layer freeze–thaw conditions

Abstract With the gradual increase of global temperature, thermokarst lakes are widely developed and become major environmental disasters in the Tundra Plateau which have impacted the stability of the project such as the Qinghai–Tibetan highway. In this study, some typical thermokarst lakes in the Qinghai–Tibet Plateau (QTP) were selected as the research object. And four samples were taken from different freezing–thawing processes of the lakes in 2019 to analyze the hydrogeochemical process of the thermokarst lake in the context of climate change. Results show that the main hydrogeochemical types of the lake water in the northern part of the study area were HCO3·Cl − Na·Ca·Mg or Cl·HCO3 − Na·Mg, whereas in the central and southern parts were mainly Cl − Na·Mg. The variations of hydrogeochemical concentration in thermokarst lake water are mainly affected by evaporation concentration, rock differentiation, freezing desalination in the active layer, and plant photosynthesis, which are mainly due to temperature changes. Furthermore, the results of the saturation index (SI) show that dolomite and calcite leaching control the hydrogeochemical composition in thermokarst lakes. In addition, the evaporation-to-inflow (E/I) ratios of the lake reach the maximum in the middle and later periods of the active layer thawing. On the contrary, the E/I values of the lakes decrease during the initial thawing or freezing periods of the active layer.

How does temperature affect aggression during and after dominance hierarchy formation in Nile tilapia?

Social animals commonly establish dominance relationships by means of aggressive interaction, leading to hierarchical stability and priority of access to limited resources by high-ranked individuals. In poikilothermic animals, temperature is a major abiotic factor influencing social and non-social behaviors, including aggression. Here, we investigated the effect of cold temperature on aggression in dominance hierarchies of the commercially important tropical fish Nile tilapia (Oreochromis niloticus). Aggression components were examined in fish shoals during hierarchy formation (T1) and after hierarchy establishment (T2) under optimal (26 °C) or cold (14 °C) temperatures, and 24 h afterwards (T3) following gradual temperature increase (14–26 °C, IT treatment), decrease (26–14 °C, DT treatment) or constant optimal conditions (26 °C, CT control). During dominance hierarchy formation, fish in cold water showed reduced aggressive interactions involving lower-intensity behaviors whereas fish under warm temperature exhibited high aggression involving escalated fighting. Following temperature alterations, at T3, aggression levels increased in the IT groups, decreased in the DT groups and remained similarly high in the CT groups. However, despite the drop of temperature in the DT treatment, aggression level at T3 in cold temperature in this treatment was similar to that in the IT treatment and CT control in warm temperature. Likewise, despite the increase of temperature, aggression level in the IT treatment at T3 was lower than that observed under the same warm temperature conditions in the DT and CT groups. Our results demonstrate that in addition to the acute effect of the current temperature on aggression in dominance hierarchies, there is a significant carryover effect of prior thermal conditions under which dominance hierarchy has been formed. Thus, cold temperature can possibly be applied during hierarchy formation for mitigating adverse social effects arising from fish grouping under captive conditions.