Thermal ecology shapes disease outcomes of entomopathogenic fungi infecting warm-adapted insects.

The thermal environment is a critical determinant of outcomes in host-pathogen interactions, yet the complexities of this relationship remain underexplored in many ecological systems. We examined the Thermal Mismatch Hypothesis (TMH) by measuring phenotypic variation in individual thermal performance profiles using a model system of two species of entomopathogenic fungi (EPF) that differ in their ecological niche, Metarhizium brunneum and M. flavoviride, and a warm-adapted model host, the mealworm Tenebrio molitor. We conducted experiments across ecologically relevant temperatures to determine the thermal performance curves for growth and virulence, measured as % survival, identify critical thresholds for these measures, and elucidate interactive host-pathogen effects. Both EPF species and the host exhibited a shared growth optima at 28 °C, while the host's growth response was moderated in sublethal pathogen infections that depended on fungus identity and temperature. However, variances in virulence patterns were different between pathogens. The fungus M. brunneum exhibited a broader optimal temperature range (23-28 °C) for virulence than M. flavoviride, which displayed a multiphasic virulence-temperature relationship with distinct peaks at 18 and 28 °C. Contrary to predictions of the TMH, both EPF displayed peak virulence at the host's optimal temperature (28 °C). The thermal profile for M. brunneum aligned more closely with that of T. molitor than that for M. flavoviride. Moreover, the individual thermal profile of M. flavoviride closely paralleled its virulence thermal profile, whereas the virulence thermal profile of M. brunneum did not track with its individual thermal performance. This suggests an indirect, midrange (23 °C) effect, where M. brunneum virulence exceeded growth. These findings suggest that the evolutionary histories and ecological adaptations of these EPF species have produced distinct thermal niches during the host interaction. This study contributes to our understanding of thermal ecology in host-pathogen interactions, underpinning the ecological and evolutionary factors that shape infection outcomes in entomopathogenic fungi. The study has ecological implications for insect population dynamics in the face of a changing climate, as well as practically for the use of these organisms in biological control.

Energy efficiency in winemaking industry: Challenges and opportunities.

The United Nations has issued a warning over the limited time for climate disaster prevention. In the last two decades, several countries have set targets to reduce fossil fuel usage and greenhouse gas emissions. These goals are tracked through the adoption of energy systems that prioritise efficiency and low-carbon alternatives, in alignment with the Sustainable Development Goals outlined by the United Nations. In the winemaking sector, the wine produced in the European Union comprised 65 % of the worldwide total from 2014 to 2018, with vineyards making up 4.7 % of its farms in 2020. Electricity is the primary source of energy used in vineries, accounting for around 90 % of the total energy consumption. The energy consumption associated with winemaking is mostly attributed to two key processes: fermentation, which accounts for 45 % to 90 % of the entire energy consumption, and bottling and storage, which contribute around 18 % of the overall energy consumption. The aim of this article is to provide an integrated review of energy efficiency in wineries through examining 144 academic publications. The selected publications cover various aspects, including sustainable energy utilisation in the wine industry, thermal performance analysis of buildings, energy efficiency assessment of systems and technologies, and the integration of renewable energy sources. A link has been established between the geographic distribution of academic publications and wine-producing countries. In relation to European publications, it is observed that research funding is associated with the energy directives of the European Union. It can also be concluded that wine customers are pushing for environmentally friendly practices. However, not everyone in the winemaking sector is moving in the same direction or at the same pace. To identify areas for improvement, winemakers must have supporting tools to manage energy use. Systems optimisation, monitoring, and accounting can be used to decrease energy consumption in winemaking processes or equipment. Progresses on sustainable energy use through greater energy efficiency and share of renewable energies in the wineries can contribute to the reduction of greenhouse gas emissions, and consequently, brings the wine industry closer to climate neutrality.

Temperature-dependent toxicity of fluoxetine alters the thermal plasticity of marine diatoms.

Anthropogenic activities have led to the emergence of pharmaceutical pollution in marine ecosystems, posing a significant threat to biodiversity in conjunction with global climate change. While the ecotoxicity of human drugs on aquatic organisms is increasingly recognized, their interactions with environmental factors, such as temperature, remain understudied. This research investigates the physiological effects of the selective serotonin reuptake inhibitor (SSRI), fluoxetine, on two diatom species, Phaeodactylum tricornutum and Thalassiosira weissflogii. Results demonstrate that fluoxetine significantly reduces growth rate and biomass production, concurrently affecting pigment contents and the thermal performance curve (TPC) of the diatoms. Fluoxetine reduces the synthesis of chlorophyll a (Chl a) and carotenoid (Car), indicating inhibition of photosynthesis and photoprotection. Furthermore, fluoxetine decreases the maximum growth rate (µmax) while increasing the optimum temperature (Topt) in both species, suggesting an altered thermal plasticity. This shift is attributed to the observed decrease in the inhibition rate of fluoxetine with rising temperatures. These findings emphasize the physiological impacts and ecological implications of fluoxetine on phytoplankton and underscore the significance of considering interactions between multiple environmental drivers when accessing the ecotoxicity of potential pollutants. The present study provides insights into crucial considerations for evaluating the impacts of pharmaceutical pollution on marine primary producers.

Fitness surfaces and local thermal adaptation in Drosophila along a latitudinal gradient.

Local adaptation is commonly cited to explain species distribution, but how fitness varies along continuous geographical gradients is not well understood. Here, we combine thermal biology and life-history theory to demonstrate that Drosophila populations along a 2500 km latitudinal cline are adapted to local conditions. We measured how heat tolerance and viability rate across eight populations varied with temperature in the laboratory and then simulated their expected cumulative Darwinian fitness employing high-resolution temperature data from their eight collection sites. Simulations indicate a trade-off between annual survival and cumulative viability, as both mortality and the recruitment of new flies are predicted to increase in warmer regions. Importantly, populations are locally adapted and exhibit the optimal combination of both traits to maximize fitness where they live. In conclusion, our method is able to reconstruct fitness surfaces employing empirical life-history estimates and reconstructs peaks representing locally adapted populations, allowing us to study geographic adaptation in silico.

An experimental evaluation of drying banana slices using a novel indirect solar dryer under variable conditions.

Novel thermal characteristics of drying banana slices in an indirect dryer are presented for four different experimental drying conditions in the forced convection mode. The novel characteristics include measuring the airflow velocity in the drying chamber, measuring the thermal profiles in different trays comprehensively and measuring the relative humidity under different conditions. Two tests are carried for 16 h in two consecutive days (8 h per day for each test). The first test is on acloudy day followed by a sunny day, while the second test is carried out on two consecutive sunny days. Tests 3 and 4 are 24 h tests with high (0.23 m/s) and low (0.11 m/s) average drying chamber airflow velocities under good solar radiation conditions. The maximum temperatures obtained in the collector and the drying chamber are around 80 and 48 °C, respectively, for the 16 h tests. Significantly lower collector and drying chamber temperatures are obtained due to cloudy conditions. Maximum collector temperatures are around 84 and 95 °C for the high and low average airflow chamber velocities for the 24 h tests. The corresponding maximum temperatures in the drying chamber are around 50 °C for the 24 tests. The final moisture ratios are 0.26 (cloudy and sunny days) and 0.20 (two sunny days), respectively, for the 16 h tests. These final moisture ratios are lower than those obtained for the 24 h tests which are 0.32 and 0.28, respectively. Increasing the drying chamber airflow velocity results in faster moisture removal during sunshine hours for the 24 h tests. For tests 1, 2, 3 and 4, the maximum average collector efficiencies during the sunshine period are around 60, 80, 40 and 10 %, respectively. The average drying efficiencies for the total solar drying period for tests 1,2,3 and 4 on day 1 are 6.9, 6.9, 5.5 and 5.7 % respectively. These values are comparable, suggesting that the average collector powers, airflow velocities and efficiencies have a very small effect on the average solar drying efficiency for the whole drying period. The quality of the bananas slices mainly in terms of the colour and shape is also compared with previous studies and commercially available products. A reasonably acceptable quality product is obtained.

Intra and interspecific variation in thermal performance and critical limits in anurans from southern Chile.

The relationship between temperature and performance can be illustrated through a thermal performance curve (TPC), which has proven useful in describing various aspects of ectotherms' thermal ecology and evolution. The parameters of the TPC can vary geographically due to large-scale variations in environmental conditions. However, only some studies have attempted to quantify how thermal performance varies over relatively small spatial scales, even in the same location or consistently among individuals within a species. Here, we quantified individual and species variation in thermal sensitivity of locomotor performance in five amphibia Eupsophus species found in the temperate rainforests of southern Chile and compared their estimates against co-occurring species that exhibit a substantially more extensive distributional range. We measured critical thermal limits and jumping performance under five different temperatures. Our results suggest that thermal responses are relatively conserved along the phylogeny, as the locomotor performance and thermal windows for activity remained narrow in Eupsophus species when compared against results observed for Batrachyla taeniata and Rhinella spinulosa. Additionally, we found significant individual differences in locomotor performance within most species, with individual consistency in performance observed across varied temperatures. Further analyses explored the influence of body size on locomotor performance and critical thermal limits within and between species. Our results suggest a trade-off scenario between thermal tolerance breadth and locomotor performance, where species exhibiting broader thermal ranges might have compromised performance. Interestingly, these traits seem partly mediated by body size variations, raising questions about potential ecological implications.

The endemic kelp Lessonia corrugata is being pushed above its thermal limits in an ocean warming hotspot.

Kelps are in global decline due to climate change, which includes ocean warming. To identify vulnerable species, we need to identify their tolerances to increasing temperatures and determine whether tolerances are altered by co-occurring drivers such as inorganic nutrient levels. This is particularly important for those species with restricted distributions, which may already be experiencing thermal stress. To identify thermal tolerance of the range-restricted kelp Lessonia corrugata, we conducted a laboratory experiment on juvenile sporophytes to measure performance (growth, photosynthesis) across its thermal range (4-22°C). We determined the upper thermal limit for growth and photosynthesis to be ~22-23°C, with a thermal optimum of ~16°C. To determine if elevated inorganic nitrogen availability could enhance thermal tolerance, we compared the performance of juveniles under low (4.5 µmol · d-1) and high (90 µmol · d-1) nitrate conditions at and above the thermal optimum (16-23.5°C). Nitrate enrichment did not enhance thermal performance at temperatures above the optimum but did lead to elevated growth rates at the thermal optimum. Our results indicate L. corrugata is likely to be extremely susceptible to moderate ocean warming and marine heatwaves. Peak sea surface temperatures during summer in eastern and northeastern Tasmania can reach up to 20-21°C, and climate projections suggest that L. corrugata's thermal limit will be regularly exceeded by 2050 as southeastern Australia is a global ocean-warming hotspot. By identifying the upper thermal limit of L. corrugata, we have taken a critical step in predicting the future of the species in a warming climate.

Hotter deserts and the impending challenges for the Spiny-tailed Lizard in India.

Ectotherms are particularly vulnerable to climate change, especially those living in extreme areas, such as deserts, where species are already thermally constrained. Using the vulnerable herbivorous lizard Saara hardwickii as a model system, we used a multi-pronged approach to understand the thermal ecology of a desert agamid and potential impacts of rising temperatures. Our data included field-based measures of operative temperatures, body temperatures, and activity, as well as lab-based measures of thermal limits, preferences, and sprint speed. As expected, the temperature dependence of locomotor performance and foraging activity were different, and in the worst-case global warming scenario (SSP5-8.5), potential sprint speed may decrease by up to 14.5% and foraging activity may decrease by up to 43.5% by 2099. Burrows are essential thermal refuges, and global warming projections suggest that S. hardwickii may be restricted to burrows for up to 9 h per day by 2099, which would greatly limit critical activities, like foraging and seeking mating opportunities. Overall, we show that key information on thermal ecology, including temperature-sensitive behaviours in the wild, is necessary to understand the multiple ways in which increasing temperatures may influence ectothermic vertebrates, especially for species like S. hardwickii that are already vulnerable to environmental change.

The impacts of diel thermal variability on growth, development and performance of wild Atlantic salmon (Salmo salar) from two thermally distinct rivers.

Temperature in many natural aquatic environments follows a diel cycle, but to date, we know little on how diel thermal cycles affect fish biology. The current study investigates the growth, development and physiological performance of wild Atlantic salmon collected from the Miramichi and Restigouche rivers (NB, Canada). Fish were collected as parr and acclimated to either 16-21 or 19-24°C diel thermal cycles throughout the parr and smolt life stages. Both Miramichi and Restigouche Atlantic salmon parr grew at similar rates during 16-21 or 19-24°C acclimations. However, as smolts, the growth rates of the Miramichi (-8% body mass day-1) and Restigouche (-38% body mass day-1) fish were significantly slower at 19-24°C, and were in fact negative, indicating loss of mass in this group. Acclimation to 19-24°C also increased Atlantic salmon CTmax. Our findings suggest that both life stage and river origin impact Atlantic salmon growth and performance in the thermal range used herein. These findings provide evidence for local adaptation of Atlantic salmon, increased vulnerability to warming temperatures, and highlight the differential impacts of these ecologically relevant diel thermal cycles on the juvenile life stages in this species.

Geographic variation in larval cold tolerance and exposure across the invasion front of a widely established forest insect.

Under global climate change, high and low temperature extremes can drive shifts in species distributions. Across the range of a species, thermal tolerance is based on acclimatization, plasticity, and may undergo selection, shaping resilience to temperature stress. In this study, we measured variation in cold temperature tolerance of early instar larvae of an invasive forest insect, Lymantria dispar dispar L. (Lepidoptera: Erebidae), using populations sourced from a range of climates within the current introduced range in the Eastern United States. We tested for population differences in chill coma recovery (CCR) by measuring recovery time following a period of exposure to a nonlethal cold temperature in 2 cold exposure experiments. A 3rd experiment quantified growth responses after CCR to evaluate sublethal effects. Our results indicate that cold tolerance is linked to regional climate, with individuals from populations sourced from colder climates recovering faster from chill coma. While this geographic gradient is seen in many species, detecting this pattern is notable for an introduced species founded from a single point-source introduction. We demonstrate that the cold temperatures used in our experiments occur in nature during cold spells after spring egg hatch, but impacts to growth and survival appear low. We expect that population differences in cold temperature performance manifest more from differences in temperature-dependent growth than acute exposure. Evaluating intraspecific variation in cold tolerance increases our understanding of the role of climatic gradients on the physiology of an invasive species, and contributes to tools for predicting further expansion.

The relationship between the body and air temperature in a terrestrial ectotherm.

Ectotherms make up the majority of terrestrial biodiversity, so it is important to understand their potential responses to climate change. Often, models aiming to achieve this understanding correlate species distributions with ambient air temperature. However, this assumes a constant relationship between the air temperature and body temperature, which determines an ectotherm's thermal performance. To test this assumption, we develop and validate a method for retrospective estimation of ectotherm body temperature using heat exchange equations. We apply the model to predict the body temperature of wild field crickets (Gryllus campestris) in Northern Spain for 1985-2019 and compare these values to air temperature. We show that while air temperature impacts ectotherm body temperature, it captures only a fraction of its thermal experience. Solar radiation can increase the body temperature by more than 20°C above air temperature with implications for physiology and behaviour. The effect of solar radiation on body temperature is particularly important given that climate change will alter cloud cover. Our study shows that the impacts of climate change on species cannot be assumed to be proportional only to changing air temperature. More reliable models of future species distributions require mechanistic links between environmental conditions and thermal ecophysiologies of species.

Hotter is not (always) better: Embracing unimodal scaling of biological rates with temperature.

Rate-temperature scaling relationships have fascinated biologists for nearly two centuries and are increasingly important in our era of global climate change. These relationships are hypothesized to originate from the temperature-dependent kinetics of rate-limiting biochemical reactions of metabolism. Several prominent theories have formalized this hypothesis using the Arrhenius model, which characterizes a monotonic temperature dependence using an activation energy E. However, the ubiquitous unimodal nature of biological temperature responses presents important theoretical, methodological, and conceptual challenges that restrict the promise for insight, prediction, and progress. Here we review the development of key hypotheses and methods for the temperature-scaling of biological rates. Using simulations, we examine the constraints of monotonic models, illustrating their sensitivity to data nuances such as temperature range and noise, and their tendency to yield variable and underestimated E, with critical consequences for climate change predictions. We also evaluate the behaviour of two prominent unimodal models when applied to incomplete and noisy datasets. We conclude with recommendations for resolving these challenges in future research, and advocate for a shift to unimodal models that better characterize the full range of biological temperature responses.

Effects of incubation temperature on the upper thermal tolerance of the imperiled longfin smelt (Spirinchus thaleichthys).

Upper thermal limits in many fish species are limited, in part, by the heart's ability to meet increased oxygen demand during high temperatures. Cardiac plasticity induced by developmental temperatures can therefore influence thermal tolerance. Here, we determined how incubation temperatures during the embryonic stage influence cardiac performance across temperatures during the sensitive larval stage of the imperiled longfin smelt. We transposed a cardiac assay for larger fish to newly hatched larvae that were incubated at 9°C, 12°C or 15°C. We measured heart rate over increases in temperature to identify the Arrhenius breakpoint temperature (TAB), a proxy for thermal optimum and two upper thermal limit metrics: temperature when heart rate is maximized (Tpeak) and when cardiac arrhythmia occurs (TArr). Higher incubation temperatures increased TAB, Tpeak and TArr, but high individual variation in all three metrics resulted in great overlap of individuals at TAB, Tpeak and TArr across temperatures. We found that the temperatures at which 10% of individuals reached Tpeak or TArr and temperatures at which number of individuals at TAB relative to Tpeak (ΔN(TAB,Tpeak)) was maximal, correlated more closely with upper thermal limits and thermal optima inferred from previous studies, compared to the mean values of the three cardiac metrics of the present study. Higher incubation temperatures increased the 10% Tpeak and TArr thresholds but maximum ΔN(TAB,Tpeak) largely remained the same, suggesting that incubation temperatures modulate upper thermal limits but not Topt for a group of larvae. Overall, by measuring cardiac performance across temperatures, we defined upper thermal limits (10% thresholds; Tpeak, 14.4-17.5°C; TArr, 16.9-20.2°C) and optima (ΔN(TAB,Tpeak), 12.4-14.4°C) that can guide conservation strategies for longfin smelt and demonstrated the potential of this cardiac assay for informing conservation plans for the early life stages of fish.

Numerical thermal assessment and theoretical analysis of horizontal-hole interlock composite insulation blocks.

In this paper, the thermal performance of 54 horizontal-hole interlocking composite insulation blocks was numerically analyzed based on the steady-state heat transfer model, the regulations were found, and prediction models for the thermal parameters of the blocks were established based on the parallel network thermal resistance model. The influence of block types and block materials on the thermal performance was studied, and it was found that the thermal performance of H-shaped interlocking insulation blocks was better than that of crossed-shaped ones, and the lower the thermal conductivity of block materials, the better the thermal performance of blocks, among which the reduction of thermal conductivity of concrete materials improved the thermal performance of blocks the most. The simulated values of thermal conductivity of H-shaped interlocking insulation blocks and thermal conductivity under the parallel network thermal resistance model were highly linearly correlated with correlation coefficients as high as 0.998 and 0.999. This finding enables the prediction models of thermal parameters of H-shaped interlocking insulation blocks to be established with high accuracy and provides an effective guide for the energy-saving design of interlocking insulation blocks wall.

Enhancing the Thermal Performance of Shape Memory Polymers: Designing a Minichannel Structure.

This research proposes a numerical approach to improve the thermal performance of shape memory polymers (SMPs) while their mechanical properties remain intact. Sixteen different 3D minichannel structures were numerically designed to investigate the impact of embedded water flow in microchannel networks on the thermal response and shape recovery of SMPs. This work employs two approaches, each with different physics: approach A focuses on solid mechanics analysis and, accordingly, thermal analysis in solids without considering the fluid. approach B tackles solid and fluid mechanics analysis and thermal analysis in both solid and fluid subdomains, which inherently calls for fluid-structure coupling in a uniform procedure. Finally, the results of these two approaches are compared to predict the SMP's thermal and mechanical behavior. The structural designs are then analyzed in terms of their shape recovery speed, recovery ratio, and recovery parameters. The results indicate that isotropic structures thermally outperform their anisotropic counterparts, exhibiting improved thermal characteristics and faster shape recovery. Additionally, it was observed that polymeric structures with a low volume fraction of embedded branches thermally perform efficiently. The findings of this study predict that the geometrical angle between the main branch and sub-branches of SMP favorably impacts the enhancement of thermal characteristics of the structure, accelerating its shape recovery. Approach B accelerates the shape recovery rate in SMPs due to fluid flow and uniform heat transfer within the structures.

Cycling temperature treatments affect estimates of digestive performance in prairie lizards (Sceloporus consobrinus).

In nature, many organisms experience a daily range of body temperatures. Thermal performance at stable temperatures is often extrapolated to predict function in cyclical environments. However, temperature order and cyclicity may influence physiological processes. The current study compared energy intake, digestive passage time and energy budgets at a stable temperature (33°C) and two temperature cycles in lizards (Sceloporus consobrinus), to determine (1) whether stable treatments adequately project performance in a cycling environment and (2) whether temperature order influences performance. Cycles had a mean temperature of 33°C, and rotated through 30°C, 33°C and 36°C daily, with equal durations of time at each temperature but differing temperature order, with warm days and cool nights in cycle 1 and cool days and warm nights in cycle 2. For analyses, performance in the stable treatment was compared with that during cycles. If temperature is the primary factor regulating performance, then performance from the stable treatment and cycles should compare favorably. However, physiological performance varied based on temperature treatment. Energy intake and budgets were similar between the stable trial and cycle 1 but not cycle 2. However, passage time did not differ. Notably, the two cycling regimes consistently varied in performance, indicating that temperature order plays a primary role in regulating performance. Physiological data collection requires careful consideration of effects of cycling versus stable temperature treatments. Stable temperatures do not consistently represent performance in cycling regimes and consideration should be paid not only to which temperatures animals experience but also to how temperature is experienced in nature.

The embryonic thermal environment has positive but weak effects on thermal tolerance later in life in the aquatic invertebrate Gammarus chevreuxi.

Recent evidence suggests that the adult phenotype is influenced by temperatures experienced in early life. However, our understanding of the extent to which the embryonic environment can modulate thermal tolerance later in life is limited, owing to the paucity of studies with appropriate experimental designs to test for this form of developmental plasticity. We investigated whether the thermal environment experienced during embryonic development affects thermal limits in later life. Embryos of the estuarine amphipod Gammarus chevreuxi were incubated until hatching to 15 °C, 20 °C and 25 °C, then reared under a common temperature. Using thermal ramping assays, we determined upper thermal limits in juveniles, four weeks post-hatch. Individuals exposed to higher temperatures during embryonic development displayed greater thermal tolerance as juveniles (acclimation response ratio ≈ 0.10-0.25 for upper lethal temperature). However, we suggest that the degree of developmental plasticity observed is limited, and will provide little benefit under future climate change scenarios.

Innovative building materials by upcycling clothing waste into thermal energy storage matrix with phase change materials.

The current volume of clothing waste reached 115 million tons in 2021 and is projected to increase to approximately 150 million tons by 2030. This significant surge in clothing waste has prompted heightened discussions regarding environmentally friendly recycling methods. Clothing presents complex properties, posing substantial challenges to recycling and usually resulting in environmental pollution when disposed. In this study, our recycling approach capitalizes on the differing melting points of textiles. This transformation was achieved through a physical process that included an opening procedure and high temperature heat compression. Textile materials exhibit exceptional thermal properties. Through experimentation on 50 g fiber specimens, thermal conductivities similar to commercial insulation materials were observed, registering an average of 0.0592 W/m·K at 20 °C and 0.06053 W/m·K at 40 °C. This study explores the impregnation of phase change materials (PCMs) into clothing waste-based specimens, equipping them with heat storage capabilities. During the experimental phase, we employed three distinct types of PCMs to evaluate their thermal properties and heat storage capacities in relation to their respective melting temperatures. Through thermal properties analysis, we determined the latent heat capacity of each specimen, ranging from a minimum of 6.63 J/g to a maximum of 75.81 J/g. Our observations indicated a reduction in peak temperature and time-leg effects attributable to the use of PCMs for surface heat flow. This research underscores the superior thermal performance of construction and building materials derived from clothing waste, enhanced by the integration of PCMs, when compared to traditional materials and other waste-derived alternatives.

Individual variation in thermally induced plasticity of metabolic rates: ecological and evolutionary implications for a warming world.

Energy metabolism is a fundamental property of life providing the energy for all processes and functions within an organism. As it is temperature-dependent, it mediates the effects of changing climate on ectotherm fitness and population dynamics. Though resting metabolic rate is a highly labile trait, part of its variation is individually consistent. Recent findings show that resting metabolic rate contains consistent variation not only in the elevations (intercepts) but also in the slopes of individual thermal dependence curves, challenging the thermal dependence assumption for this trait in several ectotherm taxa. I argue that among-individual variation in thermal metabolic curves represents a previously undetected component of ectotherm response to climate change, potentially affecting their adaptive capacity and population resilience under increasing stochasticity of thermal environment. Future studies need to examine not only the amount of among-individual variation in thermal metabolic curves across phylogenetic contexts but also other aspects concerning its mechanisms and adaptive significance to improve predictions about the impact of climate change on ectotherm population dynamics. This article is part of the theme issue 'The evolutionary significance of variation in metabolic rates'.

Cool-edge populations of the kelp Ecklonia radiata under global ocean change scenarios: strong sensitivity to ocean warming but little effect of ocean acidification.

Kelp forests are threatened by ocean warming, yet effects of co-occurring drivers such as CO2 are rarely considered when predicting their performance in the future. In Australia, the kelp Ecklonia radiata forms extensive forests across seawater temperatures of approximately 7-26°C. Cool-edge populations are typically considered more thermally tolerant than their warm-edge counterparts but this ignores the possibility of local adaptation. Moreover, it is unknown whether elevated CO2 can mitigate negative effects of warming. To identify whether elevated CO2 could improve thermal performance of a cool-edge population of E. radiata, we constructed thermal performance curves for growth and photosynthesis, under both current and elevated CO2 (approx. 400 and 1000 µatm). We then modelled annual performance under warming scenarios to highlight thermal susceptibility. Elevated CO2 had minimal effect on growth but increased photosynthesis around the thermal optimum. Thermal optima were approximately 16°C for growth and approximately 18°C for photosynthesis, and modelled performance indicated cool-edge populations may be vulnerable in the future. Our findings demonstrate that elevated CO2 is unlikely to offset negative effects of ocean warming on the kelp E. radiata and highlight the potential susceptibility of cool-edge populations to ocean warming.