Moderate Temperature Increase Research Articles

On the Feasibility of Deep Geothermal Wells Using Numerical Reservoir Simulation

This study examines the geothermal energy extraction potential from the basement rock within the Denver–Julesburg Basin, focusing on the flow performance and heat extraction efficiency of different geothermal well configurations. It specifically compares U-shaped, V-shaped, inclined V-shaped, and pipe-in-pipe configurations against enhanced geothermal system setups. Through numerical modeling, we evaluated the thermal behavior of these systems under various operational scenarios and fracture conditions. The results suggest that while closed-loop systems offer moderate temperature increases, Enhanced geothermal system configurations show substantial potential for high-temperature extraction. This underscores the importance of evaluating well configurations in complex geological settings. The insights from this study aid in strategic geothermal energy planning and development, marking significant advancements in geothermal technology and setting a foundation for future explorations and optimizations.

Failure mechanism of metallized film capacitors under DC field superimposed AC harmonic: From equipment to material

AbstractThis study focuses on the degradation behaviour of metallised film capacitors, which are the essential components for the stability of converter valves in flexible ultra‐high voltage direct current (HVDC) transmission systems. Through systematic experimentation, we investigated the failure mechanisms of MFCs under HVDC fields with superimposed harmonics, considering both equipment and material perspectives. The experiments subjected capacitors to 500 h of ageing under two conditions: a DC/AC‐superimposed field with a constant DC component of 290 kV/mm and an AC ripple rate varying from 12% to 28%, and a control group aged solely under a DC field. Our findings indicate that capacitors aged under the DC/AC‐superimposed field exhibited shorter lifespans and more significant capacitance loss than those aged under only the DC field. This difference in performance is primarily attributed to the distinct electrode loss behaviours observed under each ageing condition, which are key factors in the capacitors' capacitance decay. Moreover, the biaxially oriented polypropylene films in the DC‐aged samples showed more severe deterioration, characterised by more noticeable molecular chain scission and reduced breakdown strength, compared to those aged under the DC/AC superimposed field. This difference is partly due to the moderate temperature increase caused by harmonics, which benefits the aggregation structure, and partly to the reduced molecular structure damage from the AC field.

Soil warming effects on the transpiration of trees and shrubs in a subtropical secondary forest: A manipulative experiment

The climate warming can increase the productivity of some species while decrease that of others, therefore, knowledge of species-specific responses to warming is helpful to understand the possible trajectory of forest ecosystems. Despite the importance of the subtropical secondary broadleaf forests developed from afforestation in South China, our understanding of how the transpiration of trees and shrubs co-growing in these forests responds to soil warming is limited. To explore the effects of soil warming on transpiration and associated ecophysiological traits of trees and shrubs in wet and dry seasons, as well as to clarify respective contributions of trees and shrubs transpiration to the stand total, we conducted a manipulative experiment of soil warming (+2 ℃, WA) and control (CK) in a subtropical secondary broadleaf forest in South China, and continuously monitored the transpiration (based on sap flow) of trees, Schima superba and Acacia auriculiformis, and that (derived from leaf temperature and microclimate) of shrubs, Psychotria asiatica and Castanopsis chinensis, from 2021 to 2022. We also measured leaf water potentials, leaf nutrient status, and δ13C-derived intrinsic water use efficiency (WUEi). Soil warming did not significantly alter the transpiration of trees, with the exception of A. auriculiformis in 2022, whereas it notably increased transpiration of both shrubs. We attributed the stimulation of shrubs’ transpiration mainly to the more favorable leaf water potentials under warming condition. Due to the increased transpiration, the contribution of shrubs to stand transpiration was consequently increased, highlighting the potential role of shrubs in the hydrological dynamics of forest ecosystems. Additionally, the WUEi, soil main macro-nutrients, and leaf nutritional status of all species were not significantly affected by soil warming. These findings indicated that the carbon-water exchange and nutrient status of the studied plants can be maintained even when exposed to moderate increases in soil temperature and relatively drier condition, reflecting the resilience of the subtropical secondary broadleaf forest to possible climate warming. Further research on the interaction and competition of co-existing trees and shrubs under soil warming will improve the prediction of forest dynamics under future climate change, which benefits the efforts to conserve such forests in order to address the environmental pressure in the region.

Compound dry and hot events over major river basins of the world from 1921 to 2020

Compound dry and hot events (CDHEs) are among the most destructive compound extremes. Under global warming, changes in precipitation, temperature and their dependence make profound contributions to CDHEs. In this paper, the contributions of these three factors are explicitly quantified based on a novel mathematical method. Specifically, time series of precipitation and temperature are employed to identify CDHEs and then changes of CDHEs are attributed by using the partial derivatives-based sensitivity analysis. Based on the Climatic Research Unit Time-Series (CRU TS), a case study of CDHEs is devised for the major river basins (MRBs) of the world. The results highlight that from the period 1921–1970 to the period 1971–2020, CDHEs did occur more frequently across most MRBs. The temperature tended to make the largest contribution, followed by precipitation and the dependence between precipitation and temperature. In Africa, South America and Western Europe, the rising temperature is generally the dominant factor for increases of heatwaves that contribute to CDHEs. In Asia, increases of droughts along with increases of heatwaves raise the risk of CDHEs. For MRBs with moderate increases in temperature, increasing precipitation is shown to mitigate or even offset the risks of CDHEs. In the meantime, the increasing dependence is observed to reduce the frequency of CDHEs in the Huai He and the Mississippi even though temperature is increasing. Overall, the attributing results of CDHEs from 1921 to 2020 can serve as a reference for the preparation and mitigation of CDHEs for MRBs across the world.

Impact of Temperature Variations on Rice Production

The mean temperature might rise up to range of 2.0–4.5°C worldwide by the end of this century. Climatic variables affect the growth and development of the crop differently at different growth stages. The rate of development of a crop depends on the climate. Temperature is the primary factor that influences the growth and productivity of crops. Higher or lower temperatures than the optimum lead to improper crop development and affect rice's phenological stages. Extreme temperature may lead to early maturity of the crop and lower temperature lead to prolonged maturity of the crop which in both cases leads to a decrease in yield. A moderate increase in temperature will not have severe implications, but an increase in average temperature by 20 C will likely have strong negative effects on rice crop production. In several studies, it has been reported that high night temperature decreases the yield potential of rice. Whereas, respiratory losses have been shown to increase due to higher day temperature, leaf conductance and net assimilation rates during the day were reported to be higher.

Diverse projected climate change scenarios affect the physiology of broccoli plants to different extents.

Climate change caused by global warming involves crucial plant growth factors such as atmospheric CO2 concentration, ambient temperature or water availability. These stressors usually co-occur, causing intricate alterations in plant physiology and development. This work focuses on how elevated atmospheric CO2 levels, together with the concomitant high temperature, would affect the physiology of a relevant crop, such as broccoli. Particular attention has been paid to those defence mechanisms that contribute to plant fitness under abiotic stress. Results show that both photosynthesis and leaf transpiration were reduced in plants grown under climate change environments compared to those grown under current climate conditions. Furthermore, an induction of carbohydrate catabolism pointed to a redistribution from primary to secondary metabolism. This result could be related to a reinforcement of cell walls, as well as to an increase in the pool of antioxidants in the leaves. Broccoli plants, a C3 crop, grown under an intermediate condition showed activation of those adaptive mechanisms, which would contribute to coping with abiotic stress, as confirmed by reduced levels of lipid peroxidation relative to current climate conditions. On the contrary, the most severe climate change scenario exceeded the adaptive capacity of broccoli plants, as shown by the inhibition of growth and reduced vigour of plants. In conclusion, only a moderate increase in atmospheric CO2 concentration and temperature would not have a negative impact on broccoli crop yields.

Moderate temperature and water flow increase growth during the nursery phase of Asparagopsis armata

The red seaweed Asparagopsis armata is a target species for commercial cultivation. However, to facilitate nursery production, optimal cultivation methods for the early life stages of this species need to be developed. Therefore, this study examined the interactive effects of temperature (15 °C, 18 °C and 21 °C), irradiance (15 and 30 μmol photons m−2 s−1) and photoperiod (12 h L:12 h D and 8 h L:16 h D), and nutrient concentration (F/8 and F/4) and water flow (0.6 L min −1) on the development and growth of juvenile gametophytes of A. armata across two controlled laboratory experiments. Temperature and water flow had the greatest effect on the length of gametophytes, which was highest at 18 °C and with water flow. Gametophytes developed rapidly and were consistently largest when exposed to a 12 h L:12 h D photoperiod and growth increased when individuals were maintained at 15 μmol photons m−2 s−1 compared to 30 μmol photons m−2 s−1 under a 12 h L:12 h D photoperiod. Nutrients did not limit growth at either concentration, although contamination increased with increasing nutrient concentration and irradiance. Water flow is highly recommended during nursery cultivation of A. armata as this resulted in almost double the overall biomass productivity compared to static treatments. This work identifies critical parameters for enhancing development and growth during the early life stages of A. armata and provides fundamental information to facilitate system-specific upscaling and enable larger scale nursery production.

Thermodynamic and environmental analysis of an auto-thermal supercritical water gasification system for ammonia and power production from chicken manure

Supercritical water gasification (SCWG) technology, a clean and efficient method for organic waste treatment, has considerable application prospects in the background of carbon emission reduction. In this study, an auto-thermal SCWG system of chicken manure for NH3 and power production was proposed for recycling waste resources. Thermodynamic analysis and environmental impact assessment were conducted under different operational conditions. The system exhibited optimal energy, exergy, and cold gas efficiencies of 62.34 %, 53.75 %, and 57.75 %, while simultaneously generating 3372.11 kg/h of NH3 and 1677.1 kW of net power, all within processing 10 t/h of dry chicken manure. The global warming potential of this system was only 3.31 kg CO2-eq/kg NH3 with carbon capture and storage. The sensitivity analysis indicated that the moderate increase in gasification temperature, higher feedstock concentration, appropriate preheated water flow, and suitable feedstock distribution ratio collectively enhanced system performance by mitigating exergy destruction in the partial oxidation and heat exchange process. By converting waste heat into electrical energy rather than industrial steam, the Organic Rankine Cycle system enhances the practical viability of waste heat recovery. This work expects to provide essential theoretical guidance for the scale-up and design of the biomass waste SCWG system.

Larger diatoms are more sensitive to temperature changes and prone to succumb to warming stress

AbstractThe effects of ocean warming on phytoplankton have been extensively studied, but little has been documented on responses of differently sized diatoms to changes of temperature over wide ranges. We grew three diatom species, Thalassiosira pseudonana, Thalassiosira weissflogii, and Thalassiosira punctigera, with cell volumes of 199, 1805, and 13,599 μm3, respectively, at seven temperatures (5, 10, 15, 20, 25, 30, and 35°C) over 15 generations, and investigated their physiological responses. The optimum growth temperature (Topt), maximum growth rates (μmax), and thermal niche width (w) decreased by 16%, 48%, and 29% per order of magnitude in cell size increment, respectively. The cell volume of each species diminished significantly and linearly with increased temperatures, by 22% in T. punctigera, 17% in T. weissflogii, and 11% in T. pseudonana, respectively. However, the cellular biogenic silica (BSi) contents increased with rising temperature till the optimum growth temperature for growth, with the sensitivity of BSi to temperature changes (Q10BSi) ranging from 1.4 in the largest to 3.4 in the smallest diatom. The largest diatom T. punctigera showed the highest deactivation energy and succumbed to warmer conditions over its Topt, while the smallest was the most tolerant of warming. Although the moderate increase in growth temperature increased the diatoms' BSi levels, warming to temperatures higher than the optimum temperature for growth significantly reduced it. Our results suggest that diatoms acclimated to warmer conditions diminish their cell size but increase their mineralization of silica, which has profound significance in ocean carbon and silica biogeochemical cyclings.

Temperature effects of aluminum melt during the infiltration process into porous graphite matrix

Aluminum/graphite composites are receiving much attention due to the unique features and diverse possibilities in different fields. Generally, the aluminum melt into the inner pores of the graphite matrix requires an ambient prompting with high temperature and gas pressure. The infiltration dynamics of aluminum melt, which highly depends on the ambient temperature, would have a significant effect on the final composite’s performance. In this work, we have studied the temperature effect of aluminum melt during the infiltration process into the porous graphite matrix based on numerical simulation and experimental verification. Results show that the moderate temperature increase would effectively promote the infiltration of aluminum melt, achieving a higher filling rate with a shorter filling time. However, the promotion effects of the temperature increase would come to a certain limit due to the opposing effects of capillary porous and residual gas. The detailed influences of the temperature on the infiltration would be presented, and the final composite performance, including mechanical strength and thermal management capability, would be examined and discussed.

Adsorption of Gold from Copper–Tartrate–ThiosulfateSolutions with Ion-Exchange Resins

The adsorption behavior of gold from copper–tartrate–thiosulfate solutions with ion-exchange resins was studied in this paper. Experimental parameters include resin dosage, pH, temperature, copper, tartrate, and thiosulfate concentration. A moderate increase in resin dosage, pH, temperature, and tartrate concentration is beneficial for gold adsorption, but an excessive tartrate concentration or higher temperature depresses the adsorption process. Increasing copper and thiosulfate concentrations may competitively occupy the active sites on the resin surface, leading to a reduction in the gold adsorption capacity. The XPS and FT-IR analyses indicate that copper and gold on the resin after adsorption mainly exist in the form of Cu+ and Au+, and sulfur mainly exists in the form of SO42− and S2O32−. This implies that the use of resin for gold recovery from thiosulfate leachate may face critical challenges because there is inevitably a higher content of copper and thiosulfate.

Effects of Post-Anthesis High-Temperature Stress on Carbon Partitioning and Starch Biosynthesis in a Spring Wheat (Triticum aestivum L.) Adapted to Moderate Growth Temperatures.

This study investigates carbon partitioning in the developing endosperm of a European variety of spring wheat subjected to moderately elevated daytime temperatures (27°C/16°C d/night) from anthesis to grain maturity. Elevated daytime temperatures caused significant reductions in both fresh and dry weights and reduced the starch content of harvested grains compared to plants grown under a 20°C/16°C d/night regimen. Accelerated grain development caused by elevated temperatures was accounted for by representing plant development as thermal time (°C DPA). We examined the effects of high-temperature stress (HTS) on the uptake and partitioning of [U-14C]-sucrose supplied to isolated endosperms. HTS caused reduced sucrose uptake into developing endosperms from the second major grain-filling stage (approximately 260°C DPA) up to maturity. Enzymes involved in sucrose metabolism were unaffected by HTS, whereas key enzyme activities involved in endosperm starch deposition such as ADP-glucose pyrophosphorylase and soluble isoforms of starch synthase were sensitive to HTS throughout grain development. HTS caused a decrease in other major carbon sinks such as evolved CO2, ethanol-soluble material, cell walls and protein. Despite reductions in the labeling of carbon pools caused by HTS, the relative proportions of sucrose taken up by endosperm cells allocated to each cellular pool remain unchanged, except for evolved CO2, which increased under HTS and may reflect enhanced respiratory activity. The results of this study show that moderate temperature increases can cause significant yield reductions in some temperate wheat cultivars chiefly through three effects: reduced sucrose uptake by the endosperm, reduced starch synthesis and increased partitioning of carbon into evolved CO2.

Assessment of Climate Indices over the Carpathian Basin Based on ALADIN5.2 and REMO2015 Regional Climate Model Simulations

The Hungarian Meteorological Service has been conducting climate model simulations in order to assess the effects of climate change in the Carpathian Basin and provide data for impact research and stakeholders. Two regional climate models are used: ALADIN-Climate 5.2 (hereafter ALADIN5.2) and REMO2015. They were tested for the past when the lateral boundary conditions were taken from two sources. ERA-Interim reanalysis was used in the evaluation experiment, while the CNRM-CM5 and the MPI-ESM-LR global climate models (GCM) provided the forcings in the control experiments. The model outputs were compared with the CarpatClim-HU observational dataset for the 1981–2000 period. Future projections were carried out with the RCP4.5 and RCP8.5 scenarios, and the results were analyzed for 2021–2050 and 2071–2100. The evaluation of the results focused mainly on climate indices calculated from temperature and precipitation. The validation results showed that REMO2015 assessed the mean temperature well, but the indices based on the minimum and maximum temperature had a significant bias which has to be taken into account when interpreting future changes. The model overestimated the minimum temperature in summer, which might affect the number of tropical nights. Moreover, the maximum temperature was underestimated; thus, the derived indices, such as the occurrence of summer days and hot days, were profoundly underestimated. In comparison, ALADIN5.2 had smaller biases for the high temperature indices; moreover, the number of hot days and extremely cold days was overestimated. Taking future projections into account, we can clearly see that the results of REMO2015 show a much more moderate increase in temperature than ALADIN5.2. The reasons are yet unknown and require further investigation. In spring and summer, the number of wet days was slightly overestimated, while the number of heavy precipitation days was marginally underestimated. The projections showed the highest uncertainty in the changes in mean summer precipitation and other precipitation indices. Although the REMO2015 model assessed a decrease in precipitation, ALADIN5.2 projected an increase in precipitation with a similar magnitude.

Temperature increase modifies susceptibility to Verticillium wilt in Medicago spp and may contribute to the emergence of more aggressive pathogenic strains.

Global warming is expected to have a direct impact on plant disease patterns in agro-eco-systems. However, few analyses report the effect of moderate temperature increase on disease severity due to soil-borne pathogens. For legumes, modifications of root plant-microbe interactions either mutualistic or pathogenic due to climate change may have dramatic effects. We investigated the effect of increasing temperature on the quantitative disease resistance to Verticillium spp., a major soil-borne fungal pathogen, in the model legume Medicago truncatula and the crop M. sativa. First, twelve pathogenic strains isolated from various geographical origin were characterized with regard to their in vitro growth and pathogenicity at 20°C, 25°C and 28°C. Most of them exhibited 25°C as the optimum temperature for in vitro parameters, and between 20°C and 25°C for pathogenicity. Second, a V. alfalfae strain was adapted to the higher temperature by experimental evolution, i.e. three rounds of UV mutagenesis and selection for pathogenicity at 28°C on a susceptible M. truncatula genotype. Inoculation of monospore isolates of these mutants on resistant and susceptible M. truncatula accessions revealed that at 28°C they were all more aggressive than the wild type strain, and that some had acquired the ability to cause disease on resistant genotype. Third, one mutant strain was selected for further studies of the effect of temperature increase on the response of M. truncatula and M. sativa (cultivated alfalfa). The response of seven contrasted M. truncatula genotypes and three alfalfa varieties to root inoculation was followed using disease severity and plant colonization, at 20°C, 25°C and 28°C. With increasing temperature, some lines switched from resistant (no symptoms, no fungus in the tissues) to tolerant (no symptoms but fungal growth into the tissues) phenotypes, or from partially resistant to susceptible. Further studies in greenhouse evidence the reduction in plant fitness due to disease in susceptible lines. We thus report that root pathogenic interactions are affected by anticipated global warming, with trends towards increased plant susceptibility and larger virulence for hot-adapted strains. New threats due to hot-adapted strains of soil-borne pathogens, with possibly wider host range and increased aggressiveness, might occur.

Heat shock protein 70 and Cathepsin B genes are involved in the thermal tolerance of Aphis gossypii.

Elevated temperature can directly affect the insect pest population dynamics. Many experimental studies have indicated that high temperatures affect the biological and ecological characteristics of the widely distributed crop pest Aphis gossypii, but the molecular mechanisms underlying its response to heat stress remain unstudied. Here, we used transcriptomic analysis to explore the key genes and metabolic pathways involved in the regulation of thermotolerance in A. gossypii at 29 °C, 32 °C, and 35 °C. The results of bioinformatics analysis show that few genes were consistently differentially expressed among the higher temperature treatments compared to 29 °C, and a moderate temperature increase of 3°C can elicit gene expression changes that help A. gossypii adapt to warmer temperatures. Based on KEGG pathway enrichment analysis, we found that genes encoding four heat shock protein 70 s (Hsp70s) and nine cathepsin B (CathB) proteins were significantly upregulated at 35 °C compared with 32 °C. Genes related to glutathione production were also highly enriched between 32 °C and 29 °C. Silencing of two Hsp70s (ApHsp70A1-1 and ApHsp68) and two CathBs (ApCathB01 and ApCathB02) with RNA interference using a nanocarrier-based transdermal dsRNA delivery system significantly increased sensitivity of A. gossypii to high temperatures. A. gossypii is able to fine-tune its response across a range of temperatures, and Hsp70 and CathB genes are essential for adaption of A. gossypii to warmer temperatures. © 2023 Society of Chemical Industry.

The Impact of Different Atmospheric CO2 Concentrations on Large Scale Miocene Temperature Signatures

AbstractBased on inferences from proxy records the Miocene (23.03–5.33 Ma) was a time of amplified polar warmth compared to today. However, it remains a challenge to simulate a warm Miocene climate and pronounced polar warmth at reconstructed Miocene CO2 concentrations. Using a state‐of‐the‐art Earth‐System‐Model, we implement a high‐resolution paleobathymetry and simulate Miocene climate at different atmospheric CO2 concentrations. We estimate global mean surface warming of +3.1°C relative to the preindustrial at a CO2 level of 450 ppm. An increase of atmospheric CO2 from 280 to 450 ppm provides an individual warming of ∼1.4°C, which is as strong as all other Miocene forcing contributions combined. Substantial changes in surface albedo are vital to explain Miocene surface warming. Simulated surface temperatures fit well with proxy reconstructions at low‐ to mid‐latitudes. The high latitude cooling bias becomes less pronounced for higher atmospheric CO2 concentrations. At such CO2 levels simulated Miocene climate shows a reduced polar amplification, linked to a breakdown of seasonality in the Arctic Ocean. A pronounced warming in boreal fall is detected for a CO2 increase from 280 to 450 ppm, in comparison to weaker warming for CO2 changes from 450 to 720 ppm. Moreover, a pronounced warming in winter is detected for a CO2 increase from 450 to 720 ppm, in contrast to a moderate summer temperature increase, which is accompanied by a strong sea‐ice concentration decline that promotes cloud formation in summer via enhanced moisture availability. As a consequence planetary albedo increases and dampens the temperature response to CO2 forcing at a warmer Miocene background climate.

Effect of Sigma Phases on Moderate-Temperature Tensile Properties of Z3CN20.09M CASS Used for Primary Coolant Pipe of Nuclear Power Plant

The effect of sigma phases on the moderate-temperature tensile properties of Z3CN20.09M casting austenite stainless steel was investigated by means of isothermal treatment, scanning electron microscopy, transmission electron microscopy, instrumented nanoindentation, tensile testing, and finite element simulation. The results show that the yield strength and ultimate tensile strength of aged specimens tensile tested at moderate temperature increase remarkably with an increasing sigma phase, while the elongation at break decreased. The strain-hardening rate of aged specimens with sigma phases is higher than that of unaged specimens without sigma phases at a certain low-strain range. However, the value of the strain-hardening rate of aged specimens is lower than that of unaged specimens when the strain exceeds a certain value. The effect of the sigma phase on the tensile properties at moderate temperature is also more significant. This can be attributed to the many high-energy σ/γ2 and α/σ/γ2 incoherent phase boundaries caused by the precipitation of sigma phases. On the one hand, these boundaries hinder the movement of dislocations and subsequently accumulate dislocations to some extent, so strength is enhanced and the strain-hardening rate is improved. On the other hand, microcracks at these interfaces initiate and propagate more easily when the strain exceeds a certain value. Thus, the elongation value and the strain-hardening rate decrease.

In Silico Modelling to Assess the Electrical and Thermal Disturbance Provoked by a Metal Intracoronary Stent during Epicardial Pulsed Electric Field Ablation.

Background: Pulsed Electric Field (PEF) ablation has been recently proposed to ablate cardiac ganglionic plexi (GP) aimed to treat atrial fibrillation. The effect of metal intracoronary stents in the vicinity of the ablation electrode has not been yet assessed. Methods: A 2D numerical model was developed accounting for the different tissues involved in PEF ablation with an irrigated ablation device. A coronary artery (with and without a metal intracoronary stent) was considered near the ablation source (0.25 and 1 mm separation). The 1000 V/cm threshold was used to estimate the ‘PEF-zone’. Results: The presence of the coronary artery (with or without stent) distorts the E-field distribution, creating hot spots (higher E-field values) in the front and rear of the artery, and cold spots (lower E-field values) on the sides of the artery. The value of the E-field inside the coronary artery is very low (~200 V/cm), and almost zero with a metal stent. Despite this distortion, the PEF-zone contour is almost identical with and without artery/stent, remaining almost completely confined within the fat layer in any case. The mentioned hot spots of E-field translate into a moderate temperature increase (<48 °C) in the area between the artery and electrode. These thermal side effects are similar for pulse intervals of 10 and 100 μs. Conclusions: The presence of a metal intracoronary stent near the ablation device during PEF ablation simply ‘amplifies’ the E-field distortion already caused by the presence of the vessel. This distortion may involve moderate heating (<48 °C) in the tissue between the artery and ablation electrode without associated thermal damage.

Gene Expression Profiling of Trematomus bernacchii in Response to Thermal and Stabling Stress

The Antarctic continent is one of the most pristine environments on planet Earth, yet one of the most fragile and susceptible to the effects of the ongoing climate change. The overwhelming majority of the components of Antarctic marine trophic chain are stenotherm organisms, highly adapted to the extreme, but extremely stable, freezing temperatures of the Antarctic ocean, which have not changed significantly during the past fifteen million years. Notothenioid fishes are the most abundant representatives of ichthyofauna at these latitudes, being ubiquitously found in coastal areas across the entire continent. While different Antarctic fish species have been previously subjected to studies aimed at defining their range of thermal tolerance, or at studying the response to acute thermal stress, just a handful of authors have investigated the effects of the exposure to a moderate increase of temperature, falling within the expected forecasts for the next few decades in some areas of the Antarctica. Here, the emerald rockcod Trematomus bernacchii was used as a model species to investigate the effects of a 20-day long exposure to a +1.5 °C increase in the brain, gills and skeletal muscle, using a RNA-sequencing approach. In parallel, the experimental design also allowed for assessing the impact of stabling (including acclimation, the handling of fishes and their confinement in tanks during the experimental phase) on gene expression profiling. The results of this study clearly identified the brain as the most susceptible tissue to heat stress, with evidence of a time-dependent response dominated by an alteration of immune response, protein synthesis and folding, and energy metabolism-related genes. While the gills displayed smaller but still significant alterations, the skeletal muscle was completely unaffected by the experimental conditions. The stabling conditions also had an important impact on gene expression profiles in the brain, suggesting the presence of significant alterations of the fish nervous system, possibly due to the confinement to tanks with limited water volume and of the restricted possibility of movement. Besides providing novel insights in the molecular mechanisms underlying thermal stress in notothenioids, these findings suggest that more attention should be dedicated to an improved design of the experiments carried out on Antarctic organism, due to their extreme susceptibility to the slightest environmental alterations.

Long-term zooplankton variability in the southern Patagonian shelf, Argentina

Zooplankton can amplify changes resulting from physical forcing associated with climate change at interannual and longer time scales, so multi-year time series data for the pelagic assemblage can provide useful information about climate-ecosystem interactions. Zooplankton biomass and taxonomic composition were analyzed for the region over the southern Patagonian shelf (SPS) for March 1994 to 2012 to describe interannual patterns of variation, determine the spatial consistency and dominant scale of temporal variability, and examine their relation to the regional hydrography. The biomass of selected taxa, including primarily copepods, amphipods, and euphausiids, decreased in 2003 and remained low until 2012. These patterns were associated with a moderate increase in sea surface temperature. Our observations could not establish the causal mechanisms, but the observed biomass decrease might be related to variation in northward current flow over the SPS, which is driven by large-scale climatological forcing and would result in reduced cold-water availability over SPS. Understanding the drivers of interannual variability in zooplankton composition and biomass of this ecosystem is essential for prediction of impacts of climate change on the pelagic ecosystem, including important commercially fished species.