Discrete Pulses of Cooler Deep Water Can Decelerate Coral Bleaching During Thermal Stress: Implications for Artificial Upwelling During Heat Stress Events

AbstractScleractinian corals form the foundation of coral reefs by secreting skeletons of calcium carbonate. Their intracellular algal symbionts (Symbiodiniaceae) translocate a large proportion of photosynthate to the coral host, which is required to maintain high rates of calcification. Global warming is causing dissociation of coral host and algal symbiont, visibly presented as coral bleaching. Despite decades of study, the precise mechanisms of coral bleaching remain unknown. Separating the thermal stress response of the coral from the algal symbiont is key to understanding bleaching in tropical corals. The facultatively symbiotic northern star coral, Astrangia poculata, naturally occurs as both symbiotic and aposymbiotic (lacking algal symbionts) polyps – sometimes on the same coral colony. Thus, it is possible to separate the heat stress response of the coral host alone from the coral in symbiosis with its symbiont Breviolum psygmophilum. Using replicate symbiotic and aposymbiotic ramets of A. poculata, we conducted a chronic heat stress experiment to increase our understanding of the cellular mechanisms resulting in coral bleaching. Sustained high temperature stress resulted in photosynthetic dysfunction in B. psygmophilum, including a decline in maximum photosynthesis rate, maximum photochemical efficiency, and the absorbance peak of chlorophyll a. Interestingly, the metabolic rates of symbiotic and aposymbiotic corals were differentially impacted. RNAseq analysis revealed more differentially expressed genes between heat-stressed and control aposymbiotic colonies than heat-stressed and control symbiotic colonies. Notably, aposymbiotic colonies increased the expression of inflammation-associated genes such as nitric oxide synthases. Unexpectedly, the largest transcriptional response was observed between heat-stressed and control B. psygmophilum, including genes involved in photosynthesis, response to oxidative stress, and meiosis. Thus, it appears that the algal symbiont suppresses the immune response of the host, potentially increasing the vulnerability of the host to pathogens. The A. poculata-B. psygmophilum symbiosis provides a tractable model system for investigating thermal stress and immune challenge in scleractinian corals.

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Assessment of the coral bleaching during 2005 to decipher the thermal stress in the coral environs of the Andaman Islands using Remote Sensing

European Journal of Remote Sensing ◽

10.5721/eujrs20134624 ◽

2013 ◽

Vol 46 (1) ◽

pp. 417-430 ◽

Cited By ~ 5

Author(s):

Prakash Chandra Mohanty ◽

Ranganalli Somashekharappa Mahendra ◽

Hrusikesh Bisoyi ◽

Srinivasa Kumar Tummula ◽

George Grinson ◽

...

Keyword(s):

Remote Sensing ◽

Thermal Stress ◽

Coral Bleaching ◽

Andaman Islands

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Verification of Heat Stress Thresholds for a Health-Based Heat-Wave Definition

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-18-0246.1 ◽

2019 ◽

Vol 58 (6) ◽

pp. 1177-1194 ◽

Cited By ~ 11

Author(s):

Claudia Di Napoli ◽

Florian Pappenberger ◽

Hannah L. Cloke

Keyword(s):

Heat Stress ◽

Thermal Stress ◽

Excess Mortality ◽

Heat Waves ◽

Warning System ◽

High Heat ◽

Probability Of Detection ◽

Climate Index ◽

Test Bed ◽

Maximum Heat

AbstractHeat waves represent a threat to human health and excess mortality is one of the associated negative effects. A health-based definition for heat waves is therefore relevant, especially for early warning purposes, and it is here investigated via the universal thermal climate index (UTCI). The UTCI is a bioclimate index elaborated via an advanced model of human thermoregulation that estimates the thermal stress induced by air temperature, wind speed, moisture, and radiation on the human physiology. Using France as a test bed, the UTCI was computed from meteorological reanalysis data to assess the thermal stress conditions associated with heat-attributable excess mortality in five cities. UTCI values at different climatological percentiles were defined and evaluated in their ability to identify periods of excess mortality (PEMs) over 24 years. Using verification metrics such as the probability of detection (POD), the false alarm ratio (FAR), and the frequency bias (FB), daily minimum and maximum heat stress levels equal to or above corresponding UTCI 95th percentiles (15° ± 2°C and 34.5° ± 1.5°C, respectively) for 3 consecutive days are demonstrated to correlate to PEMs with the highest sensitivity and specificity (0.69 ≤ POD ≤ 1, 0.19 ≤ FAR ≤ 0.46, 1 ≤ FB ≤ 1.48) than minimum, maximum, and mean heat stress level singularly and other bioclimatological percentiles. This finding confirms the detrimental effect of prolonged, unusually high heat stress at day- and nighttime and suggests the UTCI 95th percentile as a health-meaningful threshold for a potential heat-health watch warning system.

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Transcriptomic Responses to Thermal Stress and Varied Phosphorus Conditions in Fugacium kawagutii

Microorganisms ◽

10.3390/microorganisms7040096 ◽

2019 ◽

Vol 7 (4) ◽

pp. 96 ◽

Cited By ~ 9

Author(s):

Senjie Lin ◽

Liying Yu ◽

Huan Zhang

Keyword(s):

Heat Stress ◽

Thermal Stress ◽

Molecular Mechanisms ◽

Organic Phosphorus ◽

Phosphorus Deficiency ◽

Dual Algorithm ◽

Quantitative Expression ◽

Wide Range ◽

Transcriptomic Responses ◽

Major Nutrients

Coral reef-associated Symbiodiniaceae live in tropical and oligotrophic environments and are prone to heat and nutrient stress. How their metabolic pathways respond to pulses of warming and phosphorus (P) depletion is underexplored. Here, we conducted RNA-seq analysis to investigate transcriptomic responses to thermal stress, phosphate deprivation, and organic phosphorus (OP) replacement in Fugacium kawagutii. Using dual-algorithm (edgeR and NOIseq) to remedy the problem of no replicates, we conservatively found 357 differentially expressed genes (DEGs) under heat stress, potentially regulating cell wall modulation and the transport of iron, oxygen, and major nutrients. About 396 DEGs were detected under P deprivation and 671 under OP utilization, both mostly up-regulated and potentially involved in photosystem and defensome, despite different KEGG pathway enrichments. Additionally, we identified 221 genes that showed relatively stable expression levels across all conditions (likely core genes), mostly catalytic and binding proteins. This study reveals a wide range of, and in many cases previously unrecognized, molecular mechanisms in F. kawagutii to cope with heat stress and phosphorus-deficiency stress. Their quantitative expression dynamics, however, requires further verification with triplicated experiments, and the data reported here only provide clues for generating testable hypotheses about molecular mechanisms underpinning responses and adaptation in F. kawagutii to temperature and nutrient stresses.

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Future Changes in Human-Biometeorological Index Classes in Three Regions of Luxembourg, Western-Central Europe

Advances in Meteorology ◽

10.1155/2015/323856 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Hanna Leona Lokys ◽

Jürgen Junk ◽

Andreas Krein

Keyword(s):

Climate Change ◽

Heat Stress ◽

Thermal Stress ◽

Thermal Comfort ◽

Central Europe ◽

Spatial Resolution ◽

Climate Index ◽

Human Thermal Comfort ◽

Air Temperatures ◽

The Impact

Projected climate change will cause increasing air temperatures affecting human thermal comfort. In the highly populated areas of Western-Central Europe a large population will be exposed to these changes. In particular Luxembourg—with its dense population and the large cross-border commuter flows—is vulnerable to changing thermal stress. Based on climate change projections we assessed the impact of climate change on human thermal comfort over the next century using two common human-biometeorological indices, the Physiological Equivalent Temperature and the Universal Thermal Climate Index. To account for uncertainties, we used a multimodel ensemble of 12 transient simulations (1971–2098) with a spatial resolution of 25 km. In addition, the regional differences were analysed by a single regional climate model run with a spatial resolution of 1.3 km. For the future, trends in air temperature, vapour pressure, and both human-biometeorological indices could be determined. Cold stress levels will decrease significantly in the near future up to 2050, while the increase in heat stress turns statistically significant in the far future up to 2100. This results in a temporarily reduced overall thermal stress level but further increasing air temperatures will shift the thermal comfort towards heat stress.

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Large-amplitude internal waves benefit corals during thermal stress

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.0650 ◽

2015 ◽

Vol 282 (1799) ◽

pp. 20140650 ◽

Cited By ~ 42

Author(s):

M. Wall ◽

L. Putchim ◽

G. M. Schmidt ◽

C. Jantzen ◽

S. Khokiattiwong ◽

...

Keyword(s):

Thermal Stress ◽

Internal Waves ◽

Coral Bleaching ◽

Large Amplitude ◽

Regional Scale ◽

Total Mortality ◽

Andaman Sea ◽

Coral Host ◽

Conservation Areas ◽

Sst Anomaly

Tropical scleractinian corals are particularly vulnerable to global warming as elevated sea surface temperatures (SSTs) disrupt the delicate balance between the coral host and their algal endosymbionts, leading to symbiont expulsion, mass bleaching and mortality. While satellite sensing of SST has proved a reliable predictor of coral bleaching at the regional scale, there are large deviations in bleaching severity and mortality on the local scale that are poorly understood. Here, we show that internal waves play a major role in explaining local coral bleaching and mortality patterns in the Andaman Sea. Despite a severe region-wide SST anomaly in May 2010, frequent upslope intrusions of cold sub-pycnocline waters due to breaking large-amplitude internal waves (LAIW) mitigated coral bleaching and mortality in shallow waters. In LAIW-sheltered waters, by contrast, bleaching-susceptible species suffered severe bleaching and total mortality. These findings suggest that LAIW benefit coral reefs during thermal stress and provide local refugia for bleaching-susceptible corals. LAIW are ubiquitous in tropical stratified waters and their swash zones may thus be important conservation areas for the maintenance of coral diversity in a warming climate. Taking LAIW into account can significantly improve coral bleaching predictions and provide a valuable tool for coral reef conservation and management.

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Borderless Heat Stress

10.5194/ems2021-28 ◽

2021 ◽

Author(s):

Chloe Brimicombe ◽

Claudia Di Napoli ◽

Rosalind Cornforth ◽

Florian Pappenberger ◽

Celia Petty ◽

...

Keyword(s):

Heat Stress ◽

Thermal Stress ◽

News Media ◽

Local Level ◽

Warning System ◽

Climate Index ◽

Country Level ◽

Media Reports ◽

Radiant Temperature ◽

The Impact

<p>Heatwaves have been increasing in frequency, duration, and intensity. They&#160;have been&#160;the deadliest hydro-meteorology&#160;hazard globally for the last 5 years&#160;according to the world meteorological organisation. In addition, they are not constrained by geography in the same sense as many other hazards and as such they are borderless.&#160;They&#160;however&#160;receive less attention, research, and funding internationally than other hazards such as floods and storms, effecting how we perceive their risk and their reporting. Here we consider the impact of heatwaves by making use of the Universal Thermal Climate Index (UTCI) for indicating heat stress. The UTCI is a biometeorological index that computes thermal stress using the parameters of 2m temperature, wind speed, mean radiant temperature and relative humidity and a body model, making it a human-centric approach to assessing thermal stress and is skilful for both indicating and forecasting heat hazards. Further a comparison to how heat impacts are reported in EM-DAT (an international disasters database) and international meteorological organisation reports, supplemented by English news media reports is made to assess whether heat impacts are sufficiently reported. In addition, we refer to specific case studies of the&#160;United&#160;Kingdom, Ghana, and Uganda to further explore impacts, risk perception and policy at a country level, because although heat is borderless impacts occur on a local scale. All this together, will provide the evidence for the development a potentially global early warning system and the implementation of climate change adaptation on a local level to build adaptive capacity and resilience to the growing risk of heat stress internationally.&#160;</p>

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Climate Change Induced Thermal Stress Caused Recurrent Coral Bleaching over Gulf of Kachchh and Malvan Marine Sanctuary, West Coast of India

10.5772/intechopen.96806 ◽

2021 ◽

Author(s):

Mohit Arora ◽

Kalyan De ◽

Nandini Ray Chaudhury ◽

Mandar Nanajkar ◽

Prakash Chauhan ◽

...

Keyword(s):

Thermal Stress ◽

Coral Reef ◽

Coral Reefs ◽

Coral Bleaching ◽

Large Scale ◽

Heat Waves ◽

Southern Oscillation ◽

Coral Cover ◽

Imminent Threat ◽

Marginal Reefs

Coral reefs are one of the most sensitive, productive, and invaluable biological resources on the earth. However, coral reefs are facing unprecedented stress due to ongoing climate changes and intensified anthropogenic disturbances globally. Elevated Sea Surface Temperature (SST) has emerged as the most imminent threat to the thermos-sensitive reef-building corals. The 2010–2014-2016 El Niño Southern Oscillation (ENSO) caused prolonged marine heat waves (MHWs) that led to the most widespread coral bleaching and mortality in the tropical Indi-Pacific regions. Coral bleaching prediction is vital for the management of the reef biodiversity, ecosystem functioning, and services. Recent decades, satellite remote sensing has emerged as a convenient tool for large-scale coral reef monitoring programs. As thermal stress is a critical physical attribute for coral bleaching hence, the present study examines the effectiveness of the elevated SSTs as a proxy to predict coral bleaching in shallow water marginal reefs. Advanced Very High-Resolution Radiometer (AVHRR) satellite data from the NOAA Coral Reef Watch’s (CRW) platform has been used for this study. Coral bleaching indices like Bleaching Threshold (BT), Positive SST Anomaly (PA), and Degree Heating Weeks (DHW) are computed to analyze the thermal stress on the coral reefs. The computed thermal stress from satellite-derived SST data over regions concurrence with the mass coral bleaching (MCB) events. This study concludes that in the last decades (2010 to 2019) the coral cover around these regions has dramatically declined due to higher SST, which indicates that the thermal stress induced recurrent bleaching events attributed to the coral loss.

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Exposure to elevated sea-surface temperatures below the bleaching threshold impairs coral recovery and regeneration following injury

10.7287/peerj.preprints.2949 ◽

2017 ◽

Author(s):

Joshua Louis Bonesso ◽

William Leggat ◽

Tracy Danielle Ainsworth

Keyword(s):

Thermal Stress ◽

Coral Bleaching ◽

Stress Responses ◽

Fluorescent Protein ◽

Sea Surface ◽

Sea Surface Temperatures ◽

Physical Damage ◽

Thermal Limits ◽

Surface Temperatures ◽

Coral Recovery

Elevated sea surface temperatures (SSTs) are linked to an increase in the frequency and severity of bleaching events due to temperatures exceeding corals’ upper thermal limits. The temperatures at which a breakdown of the coral-Symbiodinium endosymbiosis (coral bleaching) occurs are referred to as the upper thermal limits for the coral species. This breakdown of the endosymbiosis results in a reduction of corals’ nutritional uptake, growth, and tissue integrity. Periods of elevated sea surface temperature, thermal stress and coral bleaching are also linked to increased disease susceptibility and an increased frequency of storms which cause injury and physical damage to corals. Herein we aimed to determine the capacity of corals to regenerate and recover from injuries (removal of apical tips) sustained during periods of elevated sea surface temperatures which result in coral stress responses, but which do not result in coral bleaching (i.e. sub-bleaching thermal stress events). In this study, exposure of the species Acropora aspera to an elevated SST of 32°C (2°C below the bleaching threshold, 34°C) was found to result in reduced fluorescence of green fluorescent protein (GFP), reduced skeletal calcification and a lack of branch regrowth at the site of injury, compared to corals maintained under ambient SST conditions (26°C). Corals maintained under normal, ambient, sea surface temperatures expressed high GFP fluorescence at the injury site, underwent a rapid regeneration of the coral branch apical tip within 12 days of sustaining injury, and showed extensive regrowth of the coral skeleton. Taken together, our results have demonstrated that periods of sustained increased sea surface temperatures, below the corals’ bleaching threshold but above long-term summertime averages, impair coral recovery from damage, regardless of the onset or occurrence of coral bleaching .

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The Application of Infrared Thermography in Monitoring Reproduction Physiology Status of Ruminant Due to Heat Stress

Indonesian Bulletin of Animal and Veterinary Sciences ◽

10.14334/wartazoa.v30i1.2243 ◽

2020 ◽

Vol 30 (1) ◽

pp. 25

Author(s):

Fitra Aji Pamungkas ◽

B P Purwanto ◽

W Manalu ◽

A Yani ◽

R G Sianturi

Keyword(s):

Heat Stress ◽

Thermal Stress ◽

Temperature Distribution ◽

Surface Temperature ◽

Animal Welfare ◽

Infrared Thermography ◽

Physical Contact ◽

Non Invasive ◽

Safe Technique ◽

Non Destructive

Assessment on reproduction physiological parameters of ruminant caused by thermal stress usually uses invasive methods. However, these methods are less accurate because they are subjective, require a significant time and resources, and there are problems in animal welfare. Infrared thermography is one alternative solution that can be used. Infrared thermography is a modern, non-invasive, non-destructive, and safe technique to visualize thermal profile and surface temperature. This paper describes the application of infrared thermography in monitoring reproduction physiology status of ruminant. This method does not require physical contact and allows direct visualisation of temperature distribution so that it can be used as a reference in understanding and evaluating several parameters in livestock.

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