scholarly journals Coral cover surveys corroborate predictions on reef adaptive potential to thermal stress

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Oliver Selmoni ◽  
Gaël Lecellier ◽  
Laurent Vigliola ◽  
Véronique Berteaux-Lecellier ◽  
Stéphane Joost
Keyword(s):  
Heat Stress ◽  
Thermal Stress ◽  
Coral Reefs ◽  
Spatial Patterns ◽  
New Caledonia ◽  
Heat Waves ◽  
Coral Cover ◽  
Thermal Adaptation ◽  
Conservation Strategies ◽  
Adaptive Potential

AbstractAs anomalous heat waves are causing the widespread decline of coral reefs worldwide, there is an urgent need to identify coral populations tolerant to thermal stress. Heat stress adaptive potential is the degree of tolerance expected from evolutionary processes and, for a given reef, depends on the arrival of propagules from reefs exposed to recurrent thermal stress. For this reason, assessing spatial patterns of thermal adaptation and reef connectivity is of paramount importance to inform conservation strategies. In this work, we applied a seascape genomics framework to characterize the spatial patterns of thermal adaptation and connectivity for coral reefs of New Caledonia (Southern Pacific). In this approach, remote sensing of seascape conditions was combined with genomic data from three coral species. For every reef of the region, we computed a probability of heat stress adaptation, and two indices forecasting inbound and outbound connectivity. We then compared our indicators to field survey data, and observed that decrease of coral cover after heat stress was lower at reefs predicted with high probability of adaptation and inbound connectivity. Last, we discussed how these indicators can be used to inform local conservation strategies and preserve the adaptive potential of New Caledonian reefs.

scholarly journals Coral cover surveys corroborate predictions on reef adaptive potential to thermal stress

2020 ◽  
Author(s):  
Oliver Selmoni ◽  
Gaël Lecellier ◽  
Laurent Vigliola ◽  
Véronique Berteaux-Lecellier ◽  
Stéphane Joost
Keyword(s):  
Heat Stress ◽  
Thermal Stress ◽  
Coral Reefs ◽  
Spatial Patterns ◽  
New Caledonia ◽  
Heat Waves ◽  
Coral Cover ◽  
Thermal Adaptation ◽  
Conservation Strategies ◽  
Adaptive Potential

AbstractAs anomalous heat waves are causing the widespread decline of coral reefs worldwide, there is an urgent need to identify coral populations tolerant to thermal stress. Heat stress adaptive potential is the degree of tolerance expected from evolutionary processes and, for a given reef, depends on the arrival of propagules from reefs exposed to recurrent thermal stress. For this reason, assessing spatial patterns of thermal adaptation and reef connectivity is of paramount importance to inform conservation strategies.In this work, we applied a seascape genomics framework to characterize the spatial patterns of thermal adaptation and connectivity for coral reefs of New Caledonia (Southern Pacific). In this approach, remote sensing of seascape conditions was combined with genomic data from three coral species. For every reef of the region, we computed a probability of heat stress adaptation, and two indices forecasting inbound and outbound connectivity. We then compared our indicators to field survey data, and observed that decrease of coral cover after heat stress was lower at reefs predicted with high probability of adaptation and inbound connectivity. Last, we discussed how these indicators can be used to inform local conservation strategies and preserve the adaptive potential of New Caledonian reefs.

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

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.

scholarly journals Worldwide reef surveys highlight different adaptive responses to heat between coral taxa

2021 ◽  
Author(s):  
Oliver Selmoni ◽  
Gael Lecellier ◽  
Veronique Berteaux-Lecellier ◽  
Stephane Joost
Keyword(s):  
Heat Stress ◽  
Heat Waves ◽  
Coral Cover ◽  
Heat Exposure ◽  
Negative Association ◽  
Conservation Strategies ◽  
Long Term Effects ◽  
Thermal Anomalies ◽  
Adaptive Processes

Coral reefs around the world are under threat due to widespread decline of hard corals caused by anomalous heat waves. Coral taxa of different morphologies are known to have different sensitivities to heat stress. However, little is known about how long-term effects of heat exposure differ between coral taxa, nor in particular how such effects might drive adaptive processes. Here, we combined worldwide reef survey data with remotely sensed thermal anomalies to evaluate how local rates of taxa-specific coral cover were associated with heat stress. We found a negative association between coral cover and heat stress, where associations were weaker for corals with boulder-like morphology (massive corals), intermediate for corals with arborescent morphology (branching corals) and stronger for corals with encrusting or laminar morphology (plating corals). Additionally, we found that the negative association between branching coral cover and recent exposure to heat stress (measured as the year before a survey) was mitigated by the effect of long-term heat stress (measured since 1985), suggesting that adaptive processes occurred. In contrast, this "mitigating effect" of past heat-stress was not observed for either massive or plating corals. We hypothesize that these different responses to recent and past heat stress mirror different life history traits of coral taxa. For instance, branching corals are known to show higher sensitivities to heat stress and faster growth rates, two characteristics that might boost adaptive rates via evolutionary processes, when compared with other taxa. The results of this work suggest that all coral taxa, regardless of their morphology, will be "losers" of coral bleaching, and that conservation strategies should be adjusted to match taxa-specific responses to heat stress.

scholarly journals Seascape genomics as a new tool to empower coral reef conservation strategies: an example on north-western PacificAcropora digitifera

2019 ◽  
Author(s):  
Oliver Selmoni ◽  
Estelle Rochat ◽  
Gael Lecellier ◽  
Veronique Berteaux-Lecellier ◽  
Stéphane Joost
Keyword(s):  
Coral Reef ◽  
Coral Species ◽  
Heat Waves ◽  
Coral Cover ◽  
Regional Scale ◽  
Conservation Strategies ◽  
Adaptive Potential ◽  
Reef System ◽  
Genotype Frequencies ◽  
Set Up

AbstractCoral reefs are suffering a major decline due to the environmental constraints imposed by climate change. Over the last 20 years, three major coral bleaching events occurred in concomitance of anomalous heat waves, provoking a severe loss of coral cover worldwide. The conservation strategies for preserving reefs, as they are implemented now, cannot cope with global climatic shifts. Consequently, researchers are advocating the set-up of preservation frameworks to reinforce coral adaptive potential. However, the main obstacle to this implementation is that studies on coral adaption are usually hard to generalize at the scale of a reef system.Here, we study the relationships between frequencies of genetic markers with that of environmental characteristics of the sea (seascape genomics), in combination with connectivity analysis, to investigate the adaptive potential of a flagship coral species of the Ryukyu Archipelago (Japan). By associating genotype frequencies with descriptors of historical environmental conditions, we discovered six genomic regions hosting polymorphisms that might promote resistance against thermal stress. Remarkably, annotations of genes in these regions were consistent with molecular roles associated with heat responses. Furthermore, we combined information on genetic and spatial distances between reefs to predict connectivity at a regional scale.The combination between the results of these analyses portrayed the adaptive potential of this population: we were able to identify reefs carrying potential adaptive genotypes and to understand how they disperse to neighbouring reefs. This information was summarized by objective, quantifiable, and mappable indices covering the whole region, which can be extremely useful for future prioritization of reefs in conservation planning. This framework is transferable to any coral species on any reef system, and therefore represents a valuable tool for empowering preservation efforts dedicated to the protection of coral reef in warming oceans.

scholarly journals Seascape genomics reveals candidate molecular targets of heat stress adaptation in three coral species

2020 ◽  
Author(s):  
Oliver Selmoni ◽  
Gaël Lecellier ◽  
Hélène Magalon ◽  
Laurent Vigliola ◽  
Francesca Benzoni ◽  
...  
Keyword(s):  
Heat Stress ◽  
Molecular Mechanisms ◽  
Coral Species ◽  
New Caledonia ◽  
Heat Waves ◽  
Molecular Targets ◽  
Remote Sensing Data ◽  
Stress Adaptation ◽  
Nucleotide Polymorphisms ◽  
Apoptotic Pathways

AbstractAnomalous heat waves are causing a major decline of hard corals around the world and threatening the persistence of coral reefs. There are, however, reefs that had been exposed to recurrent thermal stress over the years and whose corals appeared tolerant against heat. One of the mechanisms that could explain this phenomenon is local adaptation, but the underlying molecular mechanisms are poorly known.In this work, we applied a seascape genomics approach to study heat stress adaptation in three coral species of New Caledonia (southwestern Pacific) and to uncover molecular actors potentially involved. We used remote sensing data to characterize the environmental trends across the reef system, and sampled corals living at the most contrasted sites. These samples underwent next generation sequencing to reveal single-nucleotide-polymorphisms (SNPs) of which frequencies associated with heat stress gradients. As these SNPs might underpin an adaptive role, we characterized the functional roles of the genes located in their genomic neighborhood.In each of the studied species, we found heat stress associated SNPs notably located in proximity of genes coding for well-established actors of the cellular responses against heat. Among these, we can mention proteins involved in DNA damage-repair, protein folding, oxidative stress homeostasis, inflammatory and apoptotic pathways. In some cases, the same putative molecular targets of heat stress adaptation recurred among species.Together, these results underscore the relevance and the power of the seascape genomics approach for the discovery of adaptive traits that could allow corals to persist across wider thermal ranges.

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

2019 ◽  
Vol 58 (6) ◽  
pp. 1177-1194 ◽  
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.

scholarly journals The Effect of Foliar Putrescine Application, Ammonium Exposure, and Heat Stress on Antioxidant Compounds in Cauliflower Waste

Antioxidants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 707
Author(s):  
Jacinta Collado-González ◽  
Maria Carmen Piñero ◽  
Ginés Otálora ◽  
Josefa López-Marín ◽  
Francisco M. del Amor
Keyword(s):  
Heat Stress ◽  
Thermal Stress ◽  
Heat Waves ◽  
Foliar Application ◽  
Pharmaceutical Preparations ◽  
Point Of View ◽  
Total Phenolic ◽  
Antioxidant Compounds ◽  
Short Term ◽  
Heat Effects

This work has been focused on the study of how we can affect the short heat stress on the bioactive compounds content. Some recent investigations have observed that management of nitrogen fertilization can alleviate short-term heat effects on plants. Additionally, the short-term heat stress can be also ameliorated by using putrescine, a polyamine, due to its crucial role in the adaptation of plants to heat stress Therefore, different NO3−/NH4+ ratios and a foliar putrescine treatment have been used in order to increase tolerance to thermal stress in order to take advantage of the more frequent and intense heat waves and make this crop more sustainable. So, other objective of this work is to make the cauliflower waste more attractive for nutraceutical and pharmaceutical preparations. Thus, the effect of a thermal stress combined with a 50:50 NO3−/NH4+ ratio in the nutrient solution, and the foliar application of 2.5 mM putrescine increased in the content of various sugars (inositol, glucose, and fructose), total phenolic compounds and polyamines, as well as in the antioxidant activity. The greatest accumulation of these compounds was observed in young leaves. Our results show from a physiological and agronomic point of view, that the foliar application of putrescine and the 50:50 NO3−/NH4+ treatment managed to alleviate the negative effects of the abiotic stress suffered at high temperature, yielding plants with higher antioxidant compounds content.

scholarly journals Coral reefs in the Gilbert Islands of Kiribati: Resistance, resilience, and recovery after more than a decade of multiple stressors

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255304
Author(s):  
Sara E. Cannon ◽  
Erietera Aram ◽  
Toaea Beiateuea ◽  
Aranteiti Kiareti ◽  
Max Peter ◽  
...  
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Phase Shift ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Coral Cover ◽  
Hard Coral ◽  
Turf Algae ◽  
The World ◽  
Coral Communities

Coral reefs are increasingly affected by a combination of acute and chronic disturbances from climate change and local stressors. The coral reefs of the Republic of Kiribati’s Gilbert Islands are exposed to frequent heat stress caused by central-Pacific type El Niño events, and may provide a glimpse into the future of coral reefs in other parts of the world, where the frequency of heat stress events will likely increase due to climate change. Reefs in the Gilbert Islands experienced a series of acute disturbances over the past fifteen years, including mass coral bleaching in 2004–2005 and 2009–2010, and an outbreak of the corallivorous sea star Acanthaster cf solaris, or Crown-of-Thorns (CoTs), in 2014. The local chronic pressures including nutrient loading, sedimentation and fishing vary within the island chain, with highest pressures on the reefs in urbanized South Tarawa Atoll. In this study, we examine how recovery from acute disturbances differs across a gradient of human influence in neighboring Tarawa and Abaiang Atolls from 2012 through 2018. Benthic cover and size frequency data suggests that local coral communities have adjusted to the heat stress via shifts in the community composition to more temperature-tolerant taxa and individuals. In densely populated South Tarawa, we document a phase shift to the weedy and less bleaching-sensitive coral Porites rus, which accounted for 81% of all coral cover by 2018. By contrast, in less populated Abaiang, coral communities remained comparatively more diverse (with higher percentages of Pocillopora and the octocoral Heliopora) after the disturbances, but reefs had lower overall hard coral cover (18%) and were dominated by turf algae (41%). The CoTs outbreak caused a decline in the cover and mean size of massive Porites, the only taxa that was a ‘winner’ of the coral bleaching events in Abaiang. Although there are signs of recovery, the long-term trajectory of the benthic communities in Abaiang is not yet clear. We suggest three scenarios: they may remain in their current state (dominated by turf algae), undergo a phase shift to dominance by the macroalgae Halimeda, or recover to dominance by thermally tolerant hard coral genera. These findings provide a rare glimpse at the future of coral reefs around the world and the ways they may be affected by climate change, which may allow scientists to better predict how other reefs will respond to increasing heat stress events across gradients of local human disturbance.

scholarly journals Response of Urban Heat Stress to Heat Waves in Athens (1960–2017)

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 483 ◽  
Author(s):  
George Katavoutas ◽  
Dimitra Founda
Keyword(s):  
Heat Stress ◽  
Thermal Stress ◽  
Heat Wave ◽  
Heat Waves ◽  
Hot Spot ◽  
Urban Environments ◽  
Stress Conditions ◽  
Stress Levels ◽  
Urban Heat ◽  
Urban Sites

The increasing frequency, intensity and duration of heat waves seem to follow the observed global warming in recent decades. Vulnerability to heat waves is expected to increase in urban environments mainly due to population density and the effect of the urban heat island that make cities hotter than surrounding non-urban areas. The present study focuses on a vulnerable area of the eastern Mediterranean, already characterized as a ‘hot spot’ with respect to heat-related risk and investigates the change in heat stress levels during heat wave compared to non-heat wave conditions as well as the way that heat stress levels respond to heat waves in urban, compared to non-urban, environments. The adoption of a metric accounting for both the intensity and duration of the hot event yielded a total of 46 heat wave episodes over a nearly 60-year period, but with very rare occurrence until the late 1990s and a profound increased frequency thereafter. The results reveal a difference of at least one thermal stress category between heat wave and non-heat wave periods, which is apparent across the entire range of the thermal stress distribution. The analysis demonstrates a robust intensification of nighttime heat stress conditions in urban, compared to non-urban, sites during severe heat waves. Nevertheless, severe heat waves almost equalize heat stress conditions between urban and non-urban sites during midday.

scholarly journals Thermal stress-related spatiotemporal variations in high-latitude coral reef benthic communities

Coral Reefs ◽  
2020 ◽  
Vol 39 (6) ◽  
pp. 1661-1673
Author(s):  
Nicholas P. Jones ◽  
Joana Figueiredo ◽  
David S. Gilliam
Keyword(s):  
Heat Stress ◽  
Thermal Stress ◽  
Coral Reef ◽  
High Latitude ◽  
Coral Cover ◽  
Benthic Communities ◽  
Spatiotemporal Variations ◽  
Reef Recovery ◽  
Reef Tract

AbstractHigh-latitude coral reef communities have been postulated as the first areas to undergo reorganisation under climate change. Tropicalisation has been identified in some high-latitude communities and is predicted in others, but it is unclear how the resident benthic taxa are affected. We conducted a long-term (2007–2016) assessment of changes to benthic community cover in relation to thermal stress duration on the Southeast Florida Reef Tract (SEFRT). Thermal stress events, both hot and cold, had acute (thermal stress duration affected benthic cover that year) and chronic (thermal stress duration affected benthic cover the following year) impacts on benthic cover. Chronic heat stress was associated with declines in cover of the reef-building coral families Acroporidae, Montastraeidae, Meandrinidae, Mussidae and Siderastreidae, which coupled with the absence of cold stress and rising annual temperatures boosted macroalgae cover. Cover of smaller, weedy coral families, Poritidae, Agariciidae and Astrocoeniidae, was either unaffected or positively related to heat stress duration and rising mean temperature. Thermal stress was related to spatiotemporal variations in benthic cover on the SEFRT, likely enhanced by local stressors, such as elevated nutrients and sedimentation. Coral and octocoral cover declined within four of six sub-regions, sponge cover increased in half of the sub-regions, and macroalgae cover increased in four sub-regions during the study. Under current conditions, increased macroalgae and weedy coral cover are anticipated to inhibit reef recovery.

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