scholarly journals Nitrogen sufficiency enhances thermal tolerance in habitat-forming kelp: implications for acclimation under thermal stress

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Pamela A. Fernández ◽  
Juan Diego Gaitán-Espitia ◽  
Pablo P. Leal ◽  
Matthias Schmid ◽  
Andrew T. Revill ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Thermal Tolerance

A Unifying Model to Estimate Thermal Tolerance Limits in Ectotherms Across Static, Dynamic and Fluctuating Exposures to Thermal Stress

2021 ◽  
Author(s):  
Lisa Bjerregaard Jørgensen ◽  
Hans Malte ◽  
Michael Ørsted ◽  
Nikolaj Andreasen Klahn ◽  
Johannes Overgaard
Keyword(s):  
Thermal Stress ◽  
Thermal Tolerance ◽  
Input Data ◽  
Thermal Injury ◽  
Accumulation Rate ◽  
Temperature Tolerance ◽  
Separate Experiment ◽  
Tolerance Limits ◽  
Dynamic Experiments ◽  
Different Temperatures

Abstract Temperature tolerance is critical for defining the fundamental niche of ectotherms and researchers classically use either static (exposure to a constant temperature) or dynamic (ramping temperature) assays to assess tolerance. The use of different methods complicates comparison between studies and here we present mathematical model (and R-scripts) to reconcile thermal tolerance measures obtained from static and dynamic assays. Our model uses input data from several static or dynamic experiments and is based on the well-supported assumption that thermal injury accumulation rate increases exponentially with temperature (recently re-introduced as Thermal Tolerance Landscapes). The model also assumes thermal stress at different temperatures to be additive and using experiments with Drosophila melanogaster, we validate these central assumptions by demonstrating that heat injury attained at different heat stress intensities and durations is additive. In a separate experiment we demonstrate that our model can accurately describe injury accumulation during fluctuating temperature stress and further we validate the model by successfully converting literature data of ectotherm heat tolerance (both static and dynamic assays) to a single, comparable metric (the temperature tolerated for 1 hour). The model presented here has many promising applications for the analysis of ectotherm thermal tolerance and we also discuss potential pitfalls that should be considered and avoided using this model.

Influence of osmotic stress on upper lethal temperatures in the cyprinodontid fish Fundulus heteroclitus (L.)

1972 ◽  
Vol 50 (6) ◽  
pp. 787-791 ◽  
Author(s):  
E. T. Garside ◽  
Z. K. Chin-Yuen-Kee
Keyword(s):  
Thermal Stress ◽  
Osmotic Stress ◽  
Fresh Water ◽  
Thermal Tolerance ◽  
Fundulus Heteroclitus ◽  
Thermal Acclimation ◽  
Lethal Temperature ◽  
Lethal Temperatures

Upper lethal temperatures determined for the mummichog Fundulus heteroclitus (L.) for exposures of 10 000 min ranged from 18.58C to 36.31C. Osmotic acclimations were prepared at 0, 14, and 32‰ salinity (S), at thermal acclimations of 5 and 15C, and at 14 and 32‰ S at 25C. Mummichog could not survive in the acclimatory combination of 0‰ S at 25C. Subsamples from these acclimatory combinations were exposed to thermal stress at 0, 14, and 32‰ S. Highest upper lethal temperatures were observed in isosmotic test salinity (14‰). Intermediate lethal levels occurred in seawater (32‰ S) and the lowest lethal temperatures occurred in fresh water (0‰ S). Upper lethal temperature increased with increasing thermal acclimation but generally, prior osmotic experience did not modify thermal tolerance. There was no relation between order of death and size in 18 of the 24 test combinations. In the remaining six, the largest members died first in four and the smallest died first in two test combinations.

Responses of dauerlarvae of Caenorhabditis elegans (Nematoda: Rhabditidae) to thermal stress and oxygen deprivation

1978 ◽  
Vol 56 (8) ◽  
pp. 1786-1791 ◽  
Author(s):  
Gary L. Anderson
Keyword(s):  
Thermal Stress ◽  
Caenorhabditis Elegans ◽  
Developmental Stage ◽  
Thermal Tolerance ◽  
Oxygen Deprivation ◽  
Behavior Changes ◽  
Nematode Caenorhabditis Elegans ◽  
Free Living ◽  
Anaerobic Stress ◽  
Free Living Nematode

Larval forms of the free-living nematode Caenorhabditis elegans possess the ability to enter a developmental stage which is thought to be specialized for survival in harsh environmental conditions, i.e. the dauerlarval stage. In this study the responses of dauerlarvae to thermal stress and oxygen deprivation are investigated. Oxygen consumption of dauerlarvae is less sensitive to temperature change that that of adults, with Q10 values of 1.7 and 2.6 respectively. The upper thermal tolerance limit of dauerlarvae is also different from that of adults; dauerlarvae survive approximately three times longer than adults when exposed to 37 °C. In addition to differences in thermal tolerance, dauerlarvae survive longer under anaerobic conditions than adults, 7 days and 2 days respectively. On recovery from anaerobic stress dauerlarvae exhibit behavior changes which are suggestive of emergence from the dauerlarval stage. The responses of dauerlarvae to thermal stress and oxygen deprivation appear to be important aspects of the specialization for survival in this facultative developmental stage.

scholarly journals A unifying model to estimate thermal tolerance limits in ectotherms across static, dynamic and fluctuating exposures to thermal stress

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lisa Bjerregaard Jørgensen ◽  
Hans Malte ◽  
Michael Ørsted ◽  
Nikolaj Andreasen Klahn ◽  
Johannes Overgaard
Keyword(s):  
Thermal Stress ◽  
Thermal Tolerance ◽  
Accumulation Rate ◽  
Temperature Tolerance ◽  
Separate Experiment ◽  
Time Curve ◽  
Death Time ◽  
Dynamic Experiments ◽  
Different Temperatures ◽  
Thermal Death Time

AbstractTemperature tolerance is critical for defining the fundamental niche of ectotherms and researchers classically use either static (exposure to a constant temperature) or dynamic (ramping temperature) assays to assess tolerance. The use of different methods complicates comparison between studies and here we present a mathematical model (and R-scripts) to reconcile thermal tolerance measures obtained from static and dynamic assays. Our model uses input data from several static or dynamic experiments and is based on the well-supported assumption that thermal injury accumulation rate increases exponentially with temperature (known as a thermal death time curve). The model also assumes thermal stress at different temperatures to be additive and using experiments with Drosophila melanogaster, we validate these central assumptions by demonstrating that heat injury attained at different heat stress intensities and durations is additive. In a separate experiment we demonstrate that our model can accurately describe injury accumulation during fluctuating temperature stress and further we validate the model by successfully converting literature data of ectotherm heat tolerance (both static and dynamic assays) to a single, comparable metric (the temperature tolerated for 1 h). The model presented here has many promising applications for the analysis of ectotherm thermal tolerance and we also discuss potential pitfalls that should be considered and avoided using this model.

scholarly journals Gut Microbiota of Drosophila subobscura Contributes to Its Heat Tolerance and Is Sensitive to Transient Thermal Stress

2021 ◽  
Vol 12 ◽  
Author(s):  
Angélica Jaramillo ◽  
Luis E. Castañeda
Keyword(s):  
Heat Stress ◽  
Community Structure ◽  
Thermal Stress ◽  
Gut Microbiota ◽  
Heat Tolerance ◽  
Thermal Tolerance ◽  
Drosophila Subobscura ◽  
Transient Thermal ◽  
The Impact

The gut microbiota can contribute to host physiology leading to an increase of resistance to abiotic stress conditions. For instance, temperature has profound effects on ectotherms, and the role of the gut microbiota on the thermal tolerance of ectotherms is a matter of recent research. However, most of these studies have been focused on single static temperatures instead of evaluating thermal tolerance in a wide range of stressful temperatures. Additionally, there is evidence supporting that the gut microbiota is sensitive to environmental temperature, which induces changes in its composition and diversity. These studies have evaluated the effects of thermal acclimation (>2 weeks) on the gut microbiota, but we know little about the impact of transient thermal stress on the composition and diversity of the gut microbiota. Thus, we investigated the role of the gut microbiota on the heat tolerance of Drosophila subobscura by measuring the heat tolerance of conventional and axenic flies exposed to different heat stressful temperatures (35, 36, 37, and 38°C) and estimating the heat tolerance landscape for both microbiota treatments. Conventional flies exposed to mild heat conditions exhibited higher thermal tolerance than axenic flies, whereas at higher stressful temperatures there were no differences between axenic and conventional flies. We also assessed the impact of transient heat stress on the taxonomical abundance, diversity, and community structure of the gut microbiota, comparing non-stressed flies (exposed to 21°C) and heat-stressed flies (exposed to 34°C) from both sexes. Bacterial diversity indices, bacterial abundances, and community structure changed between non-stressed and heat-stressed flies, and this response was sex-dependent. In general, our findings provide evidence that the gut microbiota influences heat tolerance and that heat stress modifies the gut microbiota at the taxonomical and structural levels. These results demonstrate that the gut microbiota contributes to heat tolerance and is also highly sensitive to transient heat stress, which could have important consequences on host fitness, population risk extinction, and the vulnerability of ectotherms to current and future climatic conditions.

scholarly journals Rapid-warming tolerance correlates with tolerance to slow warming but not growth at non-optimal temperatures in zebrafish

2020 ◽  
Author(s):  
Eirik Ryvoll Åsheim ◽  
Anna H Andreassen ◽  
Rachael Morgan ◽  
Fredrik Jutfelt
Keyword(s):  
Global Warming ◽  
Thermal Stress ◽  
Growth Performance ◽  
Danio Rerio ◽  
Thermal Tolerance ◽  
Optimal Temperature ◽  
Medium Term ◽  
Physiological Mechanisms

Global warming is predicted to increase both acute and prolonged thermal challenges for aquatic ectotherms. Severe short and medium-term thermal stress over hours to days may cause mortality, while longer sub-lethal thermal challenges may cause performance declines. The interrelationship between the responses to short, medium and longer thermal challenges is unresolved. We asked if the same individuals are tolerant to both rapid and slow warming challenges, a question which has so far received little attention. Additionally, we investigated the possibility of a thermal syndrome where individuals in a population are distributed along a warm-type to cold-type axis. We tested whether different thermal traits correlate across individuals by acclimating 200 juvenile zebrafish (Danio rerio) to sub- or supra- optimal temperatures for growth (22 and 34°C) for 40 days and measured growth and thermal tolerance at two different warming rates. We found that tolerance to rapid warming correlated with tolerance to slow warming. However, individual tolerance to neither rapid nor slow warming correlated with growth at the supra-optimal temperature. We thus find some support for a syndrome-like organisation of thermal traits, but the lack of connection between tolerance and growth-performance indicates a restricted generality of a thermal syndrome. The results suggest that tolerance to rapid warming may share underlying physiological mechanisms with tolerance to slower heating, and indicate that the relevance of acute critical thermal tolerance extends beyond the rapid ramping rates used to measure them.

scholarly journals Successive bleaching events (2019-2020) in Northeast Peninsular Malaysia revealed selective thermal acclimatization and susceptibility of hard corals at biophysical reef scale

2021 ◽  
Author(s):  
Sebastian Szereday ◽  
Affendi Yang Amri
Keyword(s):  
Thermal Stress ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Thermal Tolerance ◽  
Greenhouse Gas Emission ◽  
Southern Oscillation ◽  
Thermal Sensitivity ◽  
Peninsular Malaysia ◽  
Thermal Acclimatization ◽  
Significant Difference

Based on current greenhouse gas emission trajectories, Malaysian coral reefs are predicted to experience severe annual coral bleaching events by 2043, imminently threatening the survival of Malaysian coral reefs within this century. However, there is no field data on how Malaysian coral reefs respond to successive sequences of coral bleaching. Numerous scleractinian taxa have shown the ability to acclimatize to thermal stress events after previous exposure to heat disturbances. Nonetheless, thermal tolerance and acclimatization potentials might corroborate with accelerating warming rates and increasing frequencies of thermal stress anomalies, necessitating repeated field studies at reef scale to investigate thermal tolerance and acclimatization of scleractinian taxa. Here, we studied two successive thermal stress events during the 2019 El Niño Southern Oscillation (ENSO) and during the onset of the La Niña Oscillation in 2020. We recorded the bleaching susceptibility of scleractinian taxa to document bleaching trajectories across fine temporal and environmental gradients in Northeast Peninsular Malaysia. In addition, we analyzed historic temperature trends to demonstrate rapid warming rates (0.17° C per decade) and high return frequencies of thermal stress anomalies. Despite high maximum temperatures in both years (31.07° C and 31.74° C, respectively), accumulated thermal stress was relatively low during the bleaching episodes (Degree Heating Weeks 1.05° C-weeks and 0.61° C-weeks, respectively) and marginally varied across reef scales (0.94° C-weeks, 0.76° C-weeks, 0.48° C-weeks in 2020), suggesting a widespread thermal sensitivity of most scleractinian taxa (55.21% and 26.63% bleaching incidence in 2019 and 2020, respectively). However, significant discrepancies between satellite and in-situ temperature data were found (0.63° C; SD±0.26). Bleaching susceptibility was highly taxon-specific and contrasted historical bleaching patterns (e.g., Acropora and Montipora showed high thermal tolerance). In 2020, successive heat disturbance moderately increased bleaching susceptibility of three taxa (Galaxea, Leptastrea and Platygyra) despite lower heat stress, while Heliopora was highly susceptible in both years. Bleaching analysis of taxa on biophysical reef scales revealed significant difference across depth, wind sites (e.g., leeward and windward), and the combined interactions of wind and depth (e.g., leeward shallow) on bleaching response were significant for numerous taxa. Findings suggest thermal acclimatization of fast-growing taxa, whereby successive bleaching events and accelerating warming rates selectively pressure scleractinian assemblages.

scholarly journals Contrasting heat stress response patterns of coral holobionts across the Red Sea suggest distinct mechanisms of thermal tolerance

2020 ◽  
Author(s):  
Christian Voolstra ◽  
Jacob Valenzuela ◽  
Serdar Turkarslan ◽  
Anny Cardenas ◽  
Benjamin Hume ◽  
...  
Keyword(s):  
Heat Stress ◽  
Thermal Stress ◽  
Red Sea ◽  
Thermal Tolerance ◽  
Gulf Of Aqaba ◽  
Stress System ◽  
Response Patterns ◽  
Gene Expression Response ◽  
Stylophora Pistillata ◽  
Thermal Thresholds

Abstract Corals from the northern Red Sea, in particular the Gulf of Aqaba (GoA), have exceptionally high bleaching thresholds approaching >5°C above their maximum monthly mean (MMM) temperatures. These elevated thresholds are thought to be due to historical selection, as corals passed through the warmer Southern Red Sea during re-colonization from the Arabian Sea. To test this hypothesis, we determined thermal tolerance thresholds of GoA versus Central Red Sea (CRS) Stylophora pistillata corals using the Coral Bleaching Automated Stress System (CBASS) to run a series of standardized acute thermal stress assays. Relative thermal thresholds of GoA and CRS corals were indeed similar and exceptionally high (~7°C above MMM). However, absolute thermal thresholds of CRS corals were on average 3°C above those of GoA corals. To explore the mechanistic underpinnings, we determined gene expression response and microbiome dynamics of coral holobiont compartments. Transcriptomic responses differed markedly, with a strong response to the thermal stress in GoA corals versus a remarkably muted response in corals from the CRS. This pattern was recapitulated in the algal symbionts that showed site-specific genetic differentiation. Concomitant to this, a subset of coral and algal genes showed temperature-induced expression in GoA corals, while exhibiting fixed high expression, i.e. front-loading, in CRS corals. Bacterial community composition of GoA corals changed dramatically under heat stress, whereas CRS corals displayed consistent assemblages, indicating distinct microbial response patterns. Our work demonstrates distinct patterns underlying thermal tolerance across spatial scales, even for the same species and ocean basin. We interpret the response of GoA corals as that of a resilient population approaching a tipping point in contrast to a pattern of consistently elevated thermal resistance in CRS corals that cannot further attune. Such response differences suggest distinct thermal tolerance mechanisms that affect the response of coral populations to ocean warming.

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