scholarly journals Bleaching and post-bleaching mortality of Acropora corals on a heat-susceptible reef in 2016

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8138 ◽  
Author(s):  
Kazuhiko Sakai ◽  
Tanya Singh ◽  
Akira Iguchi
Keyword(s):  
Heat Stress ◽  
Coral Bleaching ◽  
Reef Flat ◽  
Spatial Scales ◽  
Seawater Temperature ◽  
Partial Mortality ◽  
Large Spatial Scale ◽  
Scale Temperature ◽  
Morphological Differences ◽  
The Impact

In 2016, global temperatures were the highest on record, and mass coral bleaching occurred world-wide. However, around Sesoko Island, Okinawa, southwestern Japan, the heat stress assessed by degree heating week (DHW) based on local temperature measurements was moderate in 2016; in 1998, DHW was three times higher than in 2016 (10.6 vs. 3.3 in September in respective years). On a reef flat of Sesoko Island where the effect of severe coral bleaching on coral assemblage was monitored in 1998, significant coral bleaching occurred in 2016. Bleaching of the heat stress sensitive Acropora corals began in July 2016 on the reef flat as seawater temperature rose. We observed the bleaching and post-bleaching mortality status of individual colonies of Acropora spp. in 2016 in fixed plots on the reef flat. In total, 123 Acropora colonies were followed for six months after seawater temperature became normal by multiple surveys. At the beginning of September 2016, 99.2% of colonies, were either completely (92.7%) or partially (6.5%) bleached. Of those, the dominant species or species groups were A. gemmifera (Ag), A. digitifera (Ad), and tabular Acropora (tA). For all Acropora colonies, the overall whole and partial mortality was 41.5% and 11.4%, respectively. Whole mortality rate differed significantly among species; 72.5%, 17.9%, and 27.8% in Ag, Ad, and tA, respectively. Mortality rates at the end of the surveys were similar in smaller (≤10 cm in diameter) and larger Ag, but the former suffered mortality earlier than the latter. Higher survival of smaller colonies was observed only in tA (100%), which may be associated with large morphological differences between smaller and larger colonies. Some of the dominant Acropora colonies had survived without partial mortality including 15.0% survival of the most vulnerable Ag at the end of the surveys. These results suggest that moderate heat stress may have a potential for selecting heat-tolerant genotypes. A longer period of mortality lasting for six months, was observed in Ag in addition to immediate whole mortality after bleaching, due to the continuous loss of living tissue by partial mortality. This highlights the need for multiple surveys at least during several months to accurately assess the impact of thermal stress event to corals. In contrast to DHW based on local measurements, DHW obtained from satellite data were similar between 1998 and 2016. Although satellite-based measurement of sea surface temperature is very useful to reveal variations in heat stress at a large spatial scale, temperature should be measured on site when variations at smaller spatial scales are of interest.

scholarly journals Reef location has a greater impact than coral bleaching severity on the microbiome of Pocillopora acuta

Coral Reefs ◽  
2021 ◽  
Author(s):  
Emmanuelle S. Botté ◽  
Neal E. Cantin ◽  
Véronique J. L. Mocellin ◽  
Paul A. O’Brien ◽  
Melissa M. Rocker ◽  
...  
Keyword(s):  
Heat Stress ◽  
Microbial Communities ◽  
Coral Bleaching ◽  
Health Indicators ◽  
Amplicon Sequencing ◽  
Coral Community ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Bleaching Event ◽  
The Impact

AbstractCoral reefs are increasingly threatened by heat stress events leading to coral bleaching. In 2016, a mass bleaching event affected large parts of the Great Barrier Reef (GBR). Whilst bleaching severity and coral mortality are usually monitored throughout major bleaching events, other health indicators, such as changes in microbial partners, are rarely assessed. We examined the impact of the 2016 bleaching event on the composition of the microbial communities in the coral Pocillopora acuta at Havannah Island Pandora reef, separated by 12 km on the inshore central GBR. Corals experienced moderate heat stress (3.6 and 5.3 degree heating weeks), inducing major bleaching (30–60%) at the coral community level. Samples were partitioned according to Symbiodiniaceae densities into three bleaching severity categories (mild, moderate, and severe). Whilst Symbiodiniaceae densities were similar at both reef locations, sequencing of the Symbiodiniaceae ITS2 and prokaryotic 16S rRNA genes revealed that microbial communities were significantly different between reefs, but not according to bleaching severity. Symbiodiniaceae composition was dominated by the genus Cladocopium with low abundances of Durusdinium detected in moderately and severely bleached colonies at both sites, despite site-specific ITS2 profiles. Bacterial communities were dominated by Proteobacteria and were almost entirely lacking the common Pocilloporid associate Endozoicomonas regardless of bleaching severity. Strikingly, only 11.2% of the bacterial Amplicon Sequencing Variants (ASVs) were shared between sites. This reef specificity was driven by 165 ASVs, mainly from the family Rhodobacteraceae. Comparison with previous studies suggests that the moderate heat stress experienced on the central GBR in 2016 caused the near-complete absence of Endozoicomonas. Symbiodiniaceae and bacteria (particularly Rhodobacteraceae) can be vertically transmitted in P. acuta, and larval propagation can be spatially restricted for this brooding species. Our results demonstrate that, unlike bleaching severity, location-specific factors and species-specific life history traits might have been paramount in shaping the P. acuta microbiome.

Changes in quantum efficiency of Photosystem II of symbiotic dinoflagellates of corals after heat stress, and of bleached corals sampled after the 1998 Great Barrier Reef mass bleaching event

2000 ◽  
Vol 51 (1) ◽  
pp. 63 ◽  
Author(s):  
Ross J. Jones ◽  
Selina Ward ◽  
Affendi Yang Amri ◽  
Ove Hoegh-Guldberg
Keyword(s):  
Heat Stress ◽  
Coral Bleaching ◽  
Seawater Temperature ◽  
Recovery Period ◽  
Pulse Amplitude ◽  
Bleaching Event ◽  
Algal Density ◽  
Symbiotic Algae ◽  
Temperate Coral ◽  
Symbiotic Dinoflagellates

Pulse–amplitude–modulation chlorophyll fluorometry was used to examine changes in dark-adapted Fv/Fm of endosymbiotic dinoflagellate microalgae within the tissues of the temperate coral Plesiastrea versipora exposed to elevated seawater temperature. The Fv/Fm was markedly reduced following exposure of corals to 28°C for 48 h. When corals were returned to ambient (24°C) conditions, Fv/Fm increased in an initial rapid and then secondary slower phase. Tissue discolouration (coral bleaching), caused by a significant decrease in the density of algae, was observed during the first 2–3 days of the recovery period. After 14 days, Fv/Fm was still significantly lower than in control corals. The recovery of Fv/Fm is discussed in terms of repair processes within the symbiotic algae, division of healthy algae and also the selective removal of photo-damaged dinoflagellates. Under field conditions, bleached corals sampled at Heron Island Reef during a bleaching event had significantly lower Fv/Fm than non-bleached colonies; four months after the bleaching event, there were no differences in F v /F m or algal density in corals marked as having bleached or having shown no signs of colour loss. The results of this laboratory and field study are consistent with the hypothesis that an impairment of photosynthesis occurs during heat-stress, and is the underlying cause of coral bleaching.

INFLUENCE OF GREENHOUSE SHADING AND DIFFERENT NUTRIENT MANAGEMENT PRACTICES ON ALLEVIATING HEAT STRESS, IMPROVING PLANT NUTRIENTS STATUS, FLOWERING GROWTH AND YIELD OF TOMATO

2020 ◽  
Vol 51 (4) ◽  
pp. 1001-1014
Author(s):  
Sulaiman & Sadiq
Keyword(s):  
Heat Stress ◽  
Management Practices ◽  
Nutrient Management ◽  
Block Design ◽  
Nutrient Status ◽  
Growth And Yield ◽  
Reproductive Growth ◽  
Positive Effects ◽  
Nutrition Programs ◽  
The Impact

The experiment was conducted in a greenhouse during 2017 and 2018 growing seasons to evaluate the impact of the shading and various nutrition programs on mitigating heat stress, reducing the use of chemical minerals, improving the reproductive growth and yield of tomato plant. Split-plot within Randomized Complete Block Design (RCBD) with three replications was conducted in this study. Shading factor was allocated in the main plots and the nutrition programs distributed randomly in the subplots. Results indicate that shading resulted in the decrease of daytime temperature by 5.7˚C as an average for both seasons; thus a significant increasing was found in leaf contents of macro nutrients (Nitrogen, Phosphorous, and Potassium), and micro nutrients (Iron, Zinc and Boron), except the Iron content in 2018 growing season. Furthermore, shading improved significantly the reproductive growth and tomato yield. Among the plant nutrition programs, the integrated nutrient management (INM) including the application of organic substances, bio inoculum of AMF and 50% of the recommended dose of chemical fertilizers; lead to the enhancement of nutrients content, reproductive characteristics and plant yield. Generally, combination of both shading and INM showed positive effects on plants nutrient status and persisting balance on tomato flowering growth and fruits yield.

scholarly journals Review: Impacts of shade on cattle well-being in the beef supply chain

2020 ◽  
Author(s):  
Lily N Edwards-Callaway ◽  
M Caitlin Cramer ◽  
Caitlin N Cadaret ◽  
Elizabeth J Bigler ◽  
Terry E Engle ◽  
...  
Keyword(s):  
Supply Chain ◽  
Heat Stress ◽  
Beef Cattle ◽  
Production Systems ◽  
Construction Materials ◽  
Well Being ◽  
Third Party ◽  
Ambient Temperatures ◽  
Stress Susceptibility ◽  
The Impact

ABSTRACT Shade is a mechanism to reduce heat load providing cattle with an environment supportive of their welfare needs. Although heat stress has been extensively reviewed, researched, and addressed in dairy production systems, it has not been investigated in the same manner in the beef cattle supply chain. Like all animals, beef cattle are susceptible to heat stress if they are unable to dissipate heat during times of elevated ambient temperatures. There are many factors that impact heat stress susceptibility in beef cattle throughout the different supply chain sectors, many of which relate to the production system, i.e. availability of shade, microclimate of environment, and nutrition management. The results from studies evaluating the effects of shade on production and welfare are difficult to compare due to variation in structural design, construction materials used, height, shape, and area of shade provided. Additionally, depending on operation location, shade may or may not be beneficial during all times of the year, which can influence the decision to make shade a permanent part of management systems. Shade has been shown to lessen the physiologic response of cattle to heat stress. Shaded cattle exhibit lower respiration rates, body temperatures, and panting scores compared to un-shaded cattle in weather that increases the risk of heat stress. Results from studies investigating the provision of shade indicate that cattle seek shade in hot weather. The impact of shade on behavioral patterns is inconsistent in the current body of research, some studies indicating shade provision impacts behavior and other studies reporting no difference between shaded and un-shaded groups. Analysis of performance and carcass characteristics across feedlot studies demonstrated that shaded cattle had increased ADG, improved feed efficiency, HCW, and dressing percentage when compared to cattle without shade. Despite the documented benefits of shade, current industry statistics, although severely limited in scope, indicate low shade implementation rates in feedlots and data in other supply chain sectors do not exist. Industry guidelines and third party on-farm certification programs articulate the critical need for protection from extreme weather but are not consistent in providing specific recommendations and requirements. Future efforts should include: updated economic analyses of cost versus benefit of shade implementation, exploration of producer perspectives and needs relative to shade, consideration of shade impacts in the cow-calf and slaughter plant segments of the supply chain, and integration of indicators of affective (mental) state and preference in research studies to enhance the holistic assessment of cattle welfare.

scholarly journals Scale dependence of galaxy biasing investigated by weak gravitational lensing: An assessment using semi-analytic galaxies and simulated lensing data

2018 ◽  
Vol 613 ◽  
pp. A15 ◽  
Author(s):  
Patrick Simon ◽  
Stefan Hilbert
Keyword(s):  
Gravitational Lensing ◽  
Spatial Scales ◽  
Scale Dependence ◽  
Reconstruction Technique ◽  
Weak Gravitational Lensing ◽  
Physical Scale ◽  
The Galaxy ◽  
Galaxy Bias ◽  
The Impact ◽  
Lens Galaxies

Galaxies are biased tracers of the matter density on cosmological scales. For future tests of galaxy models, we refine and assess a method to measure galaxy biasing as a function of physical scalekwith weak gravitational lensing. This method enables us to reconstruct the galaxy bias factorb(k) as well as the galaxy-matter correlationr(k) on spatial scales between 0.01hMpc−1≲k≲ 10hMpc−1for redshift-binned lens galaxies below redshiftz≲ 0.6. In the refinement, we account for an intrinsic alignment of source ellipticities, and we correct for the magnification bias of the lens galaxies, relevant for the galaxy-galaxy lensing signal, to improve the accuracy of the reconstructedr(k). For simulated data, the reconstructions achieve an accuracy of 3–7% (68% confidence level) over the abovek-range for a survey area and a typical depth of contemporary ground-based surveys. Realistically the accuracy is, however, probably reduced to about 10–15%, mainly by systematic uncertainties in the assumed intrinsic source alignment, the fiducial cosmology, and the redshift distributions of lens and source galaxies (in that order). Furthermore, our reconstruction technique employs physical templates forb(k) andr(k) that elucidate the impact of central galaxies and the halo-occupation statistics of satellite galaxies on the scale-dependence of galaxy bias, which we discuss in the paper. In a first demonstration, we apply this method to previous measurements in the Garching-Bonn Deep Survey and give a physical interpretation of the lens population.

scholarly journals Assessing population collapse of Drupella spp. (Mollusca: Gastropoda) 2 years after a coral bleaching event in the Republic of Maldives

Hydrobiologia ◽  
2021 ◽  
Author(s):  
L. Saponari ◽  
I. Dehnert ◽  
P. Galli ◽  
S. Montano
Keyword(s):  
Coral Bleaching ◽  
Prey Availability ◽  
Coral Cover ◽  
Environmental Data ◽  
High Plasticity ◽  
Bleaching Event ◽  
Coral Recovery ◽  
The Republic ◽  
The Impact ◽  
Line Intercept

AbstractCorallivory causes considerable damage to coral reefs and can exacerbate other disturbances. Among coral predators, Drupella spp. are considered as delayer of coral recovery in the Republic of Maldives, although little information is available on their ecology. Thus, we aimed to assess their population structure, feeding behaviour and spatial distribution around 2 years after a coral bleaching event in 2016. Biological and environmental data were collected using belt and line intercept transects in six shallow reefs in Maldives. The snails occurred in aggregations with a maximum of 62 individuals and exhibited a preference for branching corals. Yet, the gastropods showed a high plasticity in adapting feeding preferences to prey availability. Drupella spp. were homogenously distributed in the study area with an average of 9.04 ± 19.72 ind/200 m2. However, their occurrence was significantly different at the reef scale with the highest densities found in locations with higher coral cover. The impact of Drupella spp. appeared to be minimal with the population suffering from the loss of coral cover. We suggest that monitoring programs collect temporal- and spatial-scale data on non-outbreaking populations or non-aggregating populations to understand the dynamics of predation related to the co-occurrence of anthropogenic and natural impacts.

scholarly journals On the Spatial Patterns of Urban Thermal Conditions Using Indoor and Outdoor Temperatures

2021 ◽  
Vol 13 (4) ◽  
pp. 640
Author(s):  
Sadroddin Alavipanah ◽  
Dagmar Haase ◽  
Mohsen Makki ◽  
Mir Muhammad Nizamani ◽  
Salman Qureshi
Keyword(s):  
Heat Stress ◽  
Air Temperature ◽  
Temperature Data ◽  
Cold Spot ◽  
Temperature Pattern ◽  
Outdoor Temperature ◽  
Residential Units ◽  
Urban Settlements ◽  
The Impact ◽  
Indoor And Outdoor

The changing climate has introduced new and unique challenges and threats to humans and their environment. Urban dwellers in particular have suffered from increased levels of heat stress, and the situation is predicted to continue to worsen in the future. Attention toward urban climate change adaptation has increased more than ever before, but previous studies have focused on indoor and outdoor temperature patterns separately. The objective of this research is to assess the indoor and outdoor temperature patterns of different urban settlements. Remote sensing data, together with air temperature data collected with temperature data loggers, were used to analyze land surface temperature (outdoor temperature) and air temperature (indoor temperature). A hot and cold spot analysis was performed to identify the statistically significant clusters of high and low temperature data. The results showed a distinct temperature pattern across different residential units. Districts with dense urban settlements show a warmer outdoor temperature than do more sparsely developed districts. Dense urban settlements show cooler indoor temperatures during the day and night, while newly built districts show cooler outdoor temperatures during the warm season. Understanding indoor and outdoor temperature patterns simultaneously could help to better identify districts that are vulnerable to heat stress in each city. Recognizing vulnerable districts could minimize the impact of heat stress on inhabitants.

Evaluation of Triticum durum–Aegilops tauschii derived primary synthetics as potential sources of heat stress tolerance for wheat improvement

2021 ◽  
Vol 19 (1) ◽  
pp. 74-89
Author(s):  
Amandeep Kaur ◽  
Parveen Chhuneja ◽  
Puja Srivastava ◽  
Kuldeep Singh ◽  
Satinder Kaur
Keyword(s):  
Heat Stress ◽  
Stress Tolerance ◽  
Hexaploid Wheat ◽  
Aegilops Tauschii ◽  
Grain Filling ◽  
World Population ◽  
Potential Candidate ◽  
Terminal Heat Stress ◽  
Heat Stress Tolerance ◽  
The Impact

AbstractAddressing the impact of heat stress during flowering and grain filling is critical to sustaining wheat productivity to meet a steadily increasing demand from a rapidly growing world population. Crop wild progenitor species of wheat possess a wealth of genetic diversity for several biotic and abiotic stresses, and morphological traits and can serve as valuable donors. The transfer of useful variation from the diploid progenitor, Aegilops tauschii, to hexaploid wheat can be done through the generation of synthetic hexaploid wheat (SHW). The present study targeted the identification of potential primary SHWs to introduce new genetic variability for heat stress tolerance. Selected SHWs were screened for different yield-associated traits along with three advanced breeding lines and durum parents as checks for assessing terminal heat stress tolerance under timely and late sown conditions for two consecutive seasons. Heat tolerance index based on the number of productive tillers and thousand grain weight indicated that three synthetics, syn9809 (64.32, 78.80), syn14128 (50.30, 78.28) and syn14135 (58.16, 76.03), were able to endure terminal heat stress better than other SHWs as well as checks. One of these synthetics, syn14128, recorded a minimum reduction in thousand kernel weight (21%), chlorophyll content (2.56%), grain width (1.07%) despite minimum grain-filling duration (36.15 d) and has been selected as a potential candidate for introducing the terminal heat stress tolerance in wheat breeding programmes. Breeding efforts using these candidate donors will help develop lines with a higher potential to express the desired heat stress-tolerant phenotype under field conditions.

scholarly journals Urban Geometry Optimization to Mitigate Climate Change: Towards Energy-Efficient Buildings

2020 ◽  
Vol 13 (1) ◽  
pp. 27
Author(s):  
Hatem Mahmoud ◽  
Ayman Ragab
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Thermal Efficiency ◽  
Energy Demand ◽  
Building Blocks ◽  
Climate Projections ◽  
Climate Change Scenarios ◽  
Urban Geometry ◽  
Outdoor Spaces ◽  
The Impact

The density of building blocks and insufficient greenery in cities tend to contribute dramatically not only to increased heat stress in the built environment but also to higher energy demand for cooling. Urban planners should, therefore, be conscious of their responsibility to reduce energy usage of buildings along with improving outdoor thermal efficiency. This study examines the impact of numerous proposed urban geometry cases on the thermal efficiency of outer spaces as well as the energy consumption of adjacent buildings under various climate change scenarios as representative concentration pathways (RCP) 4.5 and 8.5 climate projections for New Aswan city in 2035. The investigation was performed at one of the most underutilized outdoor spaces on the new campus of Aswan University in New Aswan city. The potential reduction of heat stress was investigated so as to improve the thermal comfort of the investigated outdoor spaces, as well as energy savings based on the proposed strategies. Accordingly, the most appropriate scenario to be adopted to cope with the inevitable climate change was identified. The proposed scenarios were divided into four categories of parameters. In the first category, shelters partially (25–50% and 75%) covering the streets were used. The second category proposed dividing the space parallel or perpendicular to the existing buildings. The third category was a hybrid scenario of the first and second categories. In the fourth category, a green cover of grass was added. A coupling evaluation was applied utilizing ENVI-met v4.2 and Design-Builder v4.5 to measure and improve the thermal efficiency of the outdoor space and reduce the cooling energy. The results demonstrated that it is better to cover outdoor spaces with 50% of the overall area than transform outdoor spaces into canyons.

PSIII-11 Evaluating the Performance of Grow-finish Pigs Supplemented with Butipearl® Z and Kemtrace® Chromium During Natural Heat Stress Exposure

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 174-174
Author(s):  
Mark Knauer ◽  
Venkatesh Mani ◽  
Tom Marsteller ◽  
Vanessa Iseri ◽  
Brian Kremer
Keyword(s):  
Heat Stress ◽  
Feed Intake ◽  
Heat Exposure ◽  
Muscle Growth ◽  
Negative Control ◽  
Intestinal Damage ◽  
Intestinal Health ◽  
Negative Effects ◽  
Curvilinear Relationships ◽  
The Impact

Abstract Heat stress (HS) severely impacts swine leading to compromised barrier integrity, diminished intestinal health and decreased performance. ButiPEARL® Z (BPZ) is an encapsulated formulation of zinc and butyrate shown to alleviate the impact of HS by improving intestinal health. KemTRACE® Chromium (KTCr) is an organic trace mineral shown to decrease the impact of stress and improve glucose utilization, leading to muscle growth and improved performance. To test the efficacy of BPZ and KTCr on mitigating stress from natural heat exposure, a grow-finish trial was conducted from June-September. There were four treatments: negative control (NC), NC+.45kg BPZ, NC+.91kg BPZ and NC+1.82kg BPZ. Three BPZ treatments were also supplemented with 200ppb KTCr. Pigs (n=480) were randomly assigned to 96 pens at 22.5kg. Performance was measured at d0, 28, 56 and at marketing. From d56 to market, ADFI was greater (P< 0.05) for 0.45kg and 0.91kg BPZ when compared to NC and 1.82kg BPZ (3.40 and 3.35 vs. 3.26 and 3.27kg, respectively). Therefore, relationships between ADFI day 56 to market and ADFI day 0 to market with BPZ level were curvilinear (P< 0.05). Both market weight and overall ADG tended (P< 0.10) to have curvilinear relationships with BPZ level. While not different, 0.45kg and .91kg BPZ supplemented pigs were .97kg and 1.25kg heavier, respectively, on marketing day compared to control. No differences (P >0.10) were observed for Feed:Gain. Part of the negative effects of HS include decrease in feed intake which contributes to intestinal damage and decreased performance. Data from this study show that both treatment combinations were able to improve feed intake and decrease stress which might have led to the improved weight gain at the end. The data provides evidence that the combination of BPZ and KTCr may alleviate the negative effects of HS and help with the performance of grow-finish pigs during heat stress.

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