Coral Bleaching Research Articles

Colors of the ocean: Changes in the Anthropocene

Changes in the color of the ocean reflect how changes in Earth’s climate are transforming plankton ecosystems. Collecting data on both surface and underwater coloration is essential to monitoring the health of marine ecosystems across the ocean. Variations in ocean surface color, measured by satellites, hold information about the composition of plankton ecosystems. These ecosystems are sensitive to ocean temperature and to the availability of nutrients and light in the ocean. In underwater habitats, monitoring coral bleaching events serves as an important means for evaluating the health of reef ecosystems. Yet certain challenges remain to be addressed for acquiring and processing data in a standardized and reliable fashion. Current and future policies can be centered around data acquisition and integration as well as efforts for universal collaboration and broader societal impacts.

Back-to-back bleaching events in Peninsular Malaysia (2019–2020) selectively affect hard coral taxa across- and within-reef scales

The impacts of (repeat) bleaching events and the differential heat stress susceptibility of hard coral taxa are largely unknown in Malaysia, although it is part of the greater coral triangle. Here we determined bleaching trajectories of 46 hard coral taxa across- and within-reef scales based on data recorded during the first reported back-to-back coral bleaching occurrences in Malaysia between May 2019 and September 2020. Although the severity of coral bleaching in both years did not correspond to the rather small magnitude of heat stress observed, i.e., Degree Heating Weeks (DHW) of 1.05 °C-weeks and 0 °C-weeks in 2019 and 2020 respectively, we observed high levels of bleaching (55.21% and 26.63% of all surveyed colonies in 2019 and 2020, respectively). Notably, the bleaching response for both consecutive years was highly taxon-specific and significantly varied across- and within-reef scales. Mortality rates overall were low following the 2019 event, likely due to a rapid decrease in heat stress. Five of the 46 surveyed hard coral taxa exhibited more severe bleaching in 2020, despite a lower heat stress load. Interestingly, we observed low bleaching of ascribed susceptible taxa such as Acropora and Montipora, while we found taxa considered to be resilient, e.g. Heliopora and Porites, to exhibit severe bleaching, suggesting a reversal of bleaching hierarchies of taxa over time. Our findings provide a foundation for further coral bleaching studies in a region with few published records to enable more accurate regional assessments and to follow the trajectory of future coral bleaching events.

How changes projected by climate models can inform climate adaptation and marine sanctuary management: A collaborative prototype methodology

Coral reefs are highly important ecosystems providing habitat for biodiverse marine life and numerous benefits for humans. However they face immense risks from climate change. To date, Representative Concentration Pathway (RCP) climate models have aided global discussions on possible policy responses to adapt to change, but tailored climate projections at a useful scale for environmental managers are often prohibitively expensive to produce. Our research addresses this problem by presenting a novel type of collaborative, participatory research that integrates 1) site specific climate metrics from the Community Earth System Model version 2 large ensemble (CESM2-LE), 2) ecosystem response models to determine Degree Heating Months and coral bleaching impacts, and 3) collaborative social science data from environmental manager engagement to see how managers in one of the most visited marine sanctuaries in the world are enacting adaptive governance, stewarding reefs through climate impacts of the future. Our research is valuable to decision-makers seeking opportunities for innovative policy responses to climate impacts focused on experimentation and dialogue.

Irradiance dependency of oxidative stress and coral bleaching

Irradiance dependency of oxidative stress and coral bleaching

Significant response of coral-associated bacteria and their carbohydrate-active enzymes diversity to coral bleaching

Analysis of bacterial carbohydrate-active enzymes (CAZymes) contributes significantly to comprehending the response exhibited by coral symbionts to the external environment. This study explored the impact of bleaching on the bacteria and their CAZymes in coral Favites sp. through metagenomic sequencing. Notably, principal coordinates analysis (PCoA) unveiles substantial difference in bacterial communities between bleached and unbleached corals. Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidota, and Chloroflexi, exhibit noteworthy alterations during coral bleaching. CAZymes profiles in bleached coral disclosed a significant increase in Glycosyltransferases (GTs) abundance, suggesting an intensified biosynthesis of polysaccharides. Conversely, there is a marked reduction in other CAZymes abundance in bleached coral. Proteobacteria, Bacteroidota, Chlorobi, and Planctomycetota exhibit greater contributions to CAZymes in bleached corals, with Rhodobacterales, Cytophagales, Burkholderiales, Caulobacterales, and Hyphomicrobiales being the main contributors. While Acidobacteria, Actinobacteria, and Chloroflexi demonstrate higher contributions to CAZymes in unbleached corals. The changes in bacteria and their CAZymes reflect the ecological adaptability of coral holobionts when facing environmental stress. The alterations in CAZymes composition caused by bleaching events may have profound impacts on coral nutrient absorption and ecosystem stability. Therefore, understanding the dynamic changes in CAZymes is crucial for assessing the health and recovery potential of coral ecosystems.

Highest ocean heat in four centuries places Great Barrier Reef in danger

Mass coral bleaching on the Great Barrier Reef (GBR) in Australia between 2016 and 2024 was driven by high sea surface temperatures (SST)1. The likelihood of temperature-induced bleaching is a key determinant for the future threat status of the GBR2, but the long-term context of recent temperatures in the region is unclear. Here we show that the January–March Coral Sea heat extremes in 2024, 2017 and 2020 (in order of descending mean SST anomalies) were the warmest in 400 years, exceeding the 95th-percentile uncertainty limit of our reconstructed pre-1900 maximum. The 2016, 2004 and 2022 events were the next warmest, exceeding the 90th-percentile limit. Climate model analysis confirms that human influence on the climate system is responsible for the rapid warming in recent decades. This attribution, together with the recent ocean temperature extremes, post-1900 warming trend and observed mass coral bleaching, shows that the existential threat to the GBR ecosystem from anthropogenic climate change is now realized. Without urgent intervention, the iconic GBR is at risk of experiencing temperatures conducive to near-annual coral bleaching3, with negative consequences for biodiversity and ecosystems services. A continuation on the current trajectory would further threaten the ecological function4 and outstanding universal value5 of one of Earth’s greatest natural wonders.

Severe cold-water bleaching of a deep-water reef underscores future challenges for Mesophotic Coral Ecosystems

Elevated sea surface temperatures are causing an increase in coral bleaching events worldwide, and represent an existential threat to coral reefs. Early studies of Mesophotic Coral Ecosystems (MCEs) highlighted their potential as thermal refuges for shallow-water coral species in the face of predicted 21st century warming. However, recent genetic evidence implies that limited ecological connectivity between shallow- and deep-water coral communities inhibits their effectiveness as refugia; instead MCEs host distinct endemic communities that are ecologically significant in and of themselves. In either scenario, understanding the response of MCEs to climate change is critical given their ecological significance and widespread global distribution. Such an understanding has so far eluded the community, however, because of the challenges associated with long-term field monitoring, the stochastic nature of climatic events that drive bleaching, and the paucity of deep-water observations. Here we document the first observed cold-water bleaching of a mesophotic coral reef at Clipperton Atoll, a remote Eastern Tropical Pacific (ETP) atoll with high coral cover and a well-developed MCE. The severe bleaching (>70 % partially or fully bleached coral cover at 32 m depth) was driven by an anomalously shallow thermocline, and highlights a significant and previously unreported challenge for MCEs. Prompted by these observations, we compiled published cold-water bleaching events for the ETP, and demonstrate that the timing of past cold-water bleaching events in the ETP coincides with decadal oscillations in mean zonal wind strength and thermocline depth. The latter observation suggests any future intensification of easterly winds in the Pacific could be a significant concern for its MCEs. Our observations, in combination with recent reports of warm-water bleaching of Red Sea and Indian Ocean MCEs, highlight that 21st century MCEs in the Eastern Pacific face a two-pronged challenge: warm-water bleaching from above, and cold-water bleaching from below.

Corals that survive repeated thermal stress show signs of selection and acclimatization.

Climate change is transforming coral reefs by increasing the frequency and intensity of marine heatwaves, often leading to coral bleaching and mortality. Coral communities have demonstrated modest increases in thermal tolerance following repeated exposure to moderate heat stress, but it is unclear whether these shifts represent acclimatization of individual colonies or mortality of thermally susceptible individuals. For corals that survive repeated bleaching events, it is important to understand how past bleaching responses impact future growth potential. Here, we track the bleaching responses of 1,832 corals in leeward Maui through multiple marine heatwaves and document patterns of coral growth and survivorship over a seven-year period. While we find limited evidence of acclimatization at population scales, we document reduced bleaching over time in specific individuals that is indicative of acclimatization, primarily in the stress-tolerant taxa Porites lobata. For corals that survived both bleaching events, we find no relationship between bleaching response and coral growth in three of four taxa studied. This decoupling suggests that coral survivorship is a better indicator of future growth than is a coral's bleaching history. Based on these results, we recommend restoration practitioners in Hawai'i focus on colonies of Porites and Montipora with a proven track-record of growth and survivorship, rather than devote resources toward identifying and cultivating bleaching-resistant phenotypes in the lab. Survivorship followed a latitudinal thermal stress gradient, but because this gradient was small, it is likely that local environmental factors also drove differences in coral performance between sites. Efforts to reduce human impacts at low performing sites would likely improve coral survivorship in the future.

Possible toxification mechanisms of acute and chronic pentachlorophenol to Montipora digitata: Limitation of energy supply and immunotoxicity

Pentachlorophenol (PCP) is widely found in coastal environments and has various adverse effects, and its potential impact on coral reef ecosystems concerning. The scleractinian coral Montipora digitata was used for PCP stress experiments in this study. Phenotypes, physiological indicators, microbial diversity analysis and RNA sequencing were used to investigate the mechanisms underlying the responses of corals to acute and chronic PCP exposure. After 96 h of acute exposure, coral bleaching occurred at 1000 μg/LPCP and there was a significant decrease in Symbiodiniaceae density, Fv/Fm, and chlorophyll a content. Exposure to different concentrations of PCP significantly increased the content of malondialdehyde (MDA), leading to oxidative stress in corals. Chronic PCP exposure resulted in bleaching at 60 days, with the Fv/Fm significantly reduced to 0.461. Microbial diversity analysis revealed an increase in the abundance of potential pathogens, such as Vibrio, during acute PCP exposure and the emergence of the degrading bacterium Delftia during chronic PCP exposure. Transcriptional analysis showed that PCP exposure caused abnormal carbohydrate and amino acid metabolism in zooxanthella, which affected energy supply, induced immune responses, and disrupted symbiotic relationships. Corals respond to injury by boosting the expression of genes associated with signal transduction and immune response. Additionally, the expression of genes associated with environmental adaptation increased with chronic PCP exposure, which is consistent with the results of the microbial diversity analysis. These results indicate that PCP exposure might affect the balance of coral- zooxanthellae symbiosis in the stony coral M. digitata, impairing coral health and leading to bleaching.

Local conditions modulated the effects of marine heatwaves on coral bleaching in subtropical Hong Kong waters

A mass coral bleaching event occurred in the summer of 2022 in subtropical Hong Kong, driven by two marine heatwaves (MHWs) with high intensities of 1.56 and 0.86 °C above a mean climate condition, both MHWs 7 days with a short gap of 4 days during the strong La Niña year. A transect survey was conducted at nine study sites in three regions, which revealed widespread coral bleaching with bleached coral cover ranging from 2.4 to 70.3%. In situ environmental data revealed the presence of a thermocline and halocline. Local conditions, including depth and wave exposure, significantly influenced the bleaching response. Shallow-water (2–4 m) corals were primarily affected, particularly in sheltered and moderately sheltered sites that exhibited higher levels of bleached coral cover (42.97 ± 15.4% and 44.93 ± 29.4%, respectively) compared to the exposed sites (31.8 ± 5.2%). Bleaching in deep waters (4–6 m) was minimal, with only a few colonies of Goniopora at two of the three sheltered sites exhibiting bleaching (1.7 ± 1.5%). Heat stress resistance differed between coral genera. Recovery rate for four common coral genera is low for Acropora tumida. Additionally, a minor hypoxia event was found to cause mortality of non-coral benthos at a sheltered site (Sharp Island). These findings highlight the alarming impact of extreme heatwaves on subtropical coral communities and underscore the importance of monitoring coral bleaching.

Climate Change: A Caribbean Perspective

Climate change has been expedited by human activity. The Caribbean has seen the rapid progression of climate change, global warming and its harmful effects. In the Caribbean, we have an abundance of natural wonders and are considered a tourist attraction, but the progression of global warming and climate change is proving to be a threat. Guyana, which is a booming economy in the region, is developing rapidly but trying to preserve its rainforest and co-exist sustainably with the environment. It is noted that the Caribbean is experiencing more extremes of weather conditions such as hurricanes and other adverse effects of climate change including rising sea levels and bleaching of coral reefs. It is important that, as we develop, we preserve our natural attractions which encourage tourism, our diverse flora and fauna and the health of our population. Regional groups have acknowledged this and see the importance of taking action to preserve the Caribbean and its Small Island Developing States. These Small Island Developing States are disproportionately affected by climate change considering their small contribution to Green House Gases compared to the much larger developed nations. It is of paramount importance that policies and actions materialize to combat climate change and preserve health in the region. It is also crucial that we be a voice for our region bringing the phenomenon of climate change and health in the Caribbean to the global forum.

Alleviating Coral Thermal Stress via Inoculation with Quorum Quenching Bacteria.

In the background of global warming, coral bleaching induced by elevated seawater temperature is the primary cause of coral reef degradation. Coral microbiome engineering using the beneficial microorganisms for corals (BMCs) has become a hot spot in the field of coral reef conservation and restoration. Investigating the potential of alleviating thermal stress by quorum quenching (QQ) bacteria may provide more tools for coral microbial engineering remediation. In this study, QQ bacteria strain Pseudoalteromonas piscicida SCSIO 43740 was screened among 75 coral-derived bacterial strains, and its quorum sensing inhibitor (QSI) compound was isolated and identified as 2,4-di-tert-butylphenol (2,4-DTBP). Then, the thermal stress alleviating potential of QQ bacteria on coral Pocillopora damicornis was tested by a 30-day controlled experiment with three different treatments: control group (Con: 29°C), high temperature group (HT: 31°C), and the group of high temperature with QQ bacteria inoculation (HTQQ: 31°C + QQ bacteria). The results showed that QQ bacteria SCSIO 43740 inoculation can significantly mitigate the loss of symbiotic algae and impairment of photosynthesis efficiency of coral P. damicornis under thermal stress. Significant difference in superoxide dismutase (SOD) and catalase (CAT) enzyme activities between HT and HTQQ was not observed. In addition, QQ bacteria inoculation suppressed the coral microbial community beta-dispersion and improved the stability of microbial co-occurrence network under thermal stress. It was suggested that QQ bacteria inoculation can alleviate coral thermal stress via reshaping microbial interaction and maintain community stability of coral microbiome. This study provided new evidence for the probiotic function of QQ bacteria in corals, which shedding light on the development of new microbiological tools for coral reef conservation.

Diel transcriptional responses of coral-Symbiodiniaceae holobiont to elevated temperature

Coral exhibits diel rhythms in behavior and gene transcription. However, the influence of elevated temperature, a key factor causing coral bleaching, on these rhythms remains poorly understood. To address this, we examined physiological, metabolic, and gene transcription oscillations in the Acropora tenuis-Cladocopium sp. holobiont under constant darkness (DD), light-dark cycle (LD), and LD with elevated temperature (HLD). Under LD, the values of photosystem II efficiency, reactive oxygen species leakage, and lipid peroxidation exhibited significant diel oscillations. These oscillations were further amplified during coral bleaching under HLD. Gene transcription analysis identified 24-hour rhythms for specific genes in both coral and Symbiodiniaceae under LD. Notably, these rhythms were disrupted in coral and shifted in Symbiodiniaceae under HLD. Importantly, we identified over 20 clock or clock-controlled genes in this holobiont. Specifically, we suggested CIPC (CLOCK-interacting pacemaker-like) gene as a core clock gene in coral. We observed that the transcription of two abundant rhythmic genes encoding glycoside hydrolases (CBM21) and heme-binding protein (SOUL) were dysregulated by elevated temperature. These findings indicate that elevated temperatures disrupt diel gene transcription rhythms in the coral-Symbiodiniaceae holobiont, affecting essential symbiosis processes, such as carbohydrate utilization and redox homeostasis. These disruptions may contribute to the thermal bleaching of coral.

2DH Numerical Study of Solitary Wave Processes around an Idealized Reef-Fringed Island

In order to better understand the role of coral reefs around an isolated island in mitigating tsunami hazards, this study performed a horizontally two-dimensional (2DH) numerical study of tsunami-like solitary wave propagation and run-up around an idealized reef-fringed island. The shock-capturing Boussinesq wave model, the FUNWAVE-TVD is used in the present study and well-validated with existing experimental data for its robustness in predicting 2DH solitary wave processes around an island. Based on the validated model, the typical solitary propagation process around the reef-fringed island and the effects of morphological and hydrodynamic parameters on the maximum run-up heights were systematically investigated. It is found that coral reefs can effectively reduce maximum run-up heights around an isolated island. The reef flat’s water depth, reef flat width, and reef surface roughness are the main factors affecting maximum run-up heights around an island, while the fore-reef slope has little impact. For the idealized reef-fringed island in this study, sea-level rise will cause coral reefs to lose their protective capability on the lee side, and the presence of coral reefs may even enhance tsunami hazards around an island when the reef flat width is very narrow or coral bleaching happens.

High coral heat tolerance at local-scale thermal refugia

Marine heatwaves and mass bleaching have devastated coral populations globally, yet bleaching severity often varies among reefs. To what extent a reef’s past exposure to heat stress influences coral bleaching and mortality remains uncertain. Here we identify persistent local-scale hotspots and thermal refugia among the reefs of Palau, Micronesia, based on 36 years of satellite-derived cumulative heat stress (degree heating weeks–DHW, units: °C-weeks). One possibility is that hotspots may harbour more heat tolerant corals due to acclimatisation, directional selection, and/or loss of tolerant genotypes. Historic patterns of assemblage-wide mass bleaching and marine heatwaves align with this hypothesis, with DHW-bleaching responses of hotspots occurring at 1.7°C-weeks greater heat stress than thermal refugia. This trend was consistent yet weaker for Acropora and corymbose Acropora, with severe bleaching risk reduced by 4–10% at hotspots. However, we find a contrasting pattern for Acropora digitifera exposed to a simulated marine heatwave. Fragments of 174 colonies were collected from replicate hotspot and thermal refugium outer reefs with comparable wave exposure and depth. Higher heat tolerance at thermal refugia (+0.7°C-weeks) and a correlation with tissue biomass suggests that factors other than DHW may overwhelm any spatially varying effects of past DHW exposure. Further, we found considerable A. digitifera heat tolerance variability across sites; compared to the least-tolerant 10% of colonies, the most-tolerant 10% could withstand additional heat stresses of 5.2 and 4.1°C-weeks for thermal refugia and hotspots, respectively. Our study demonstrates that hotspot reefs do not necessarily harbour more heat tolerant corals than nearby thermal refugia, and that mass bleaching patterns do not necessarily predict species responses. This nuance has important implications for designing climate-smart initiatives; for instance, in the search for heat tolerant corals, our results suggest that investing effort into identifying the most tolerant colonies within individual reefs may be warranted.

Improved research on coral bleaching detection model based on FCOS model

Coral bleaching detection is vital for assessing coral reef health. This paper introduces FCOS_EfficientNET, an improved model that enhances accuracy, recall, and real-time performance in coral bleaching detection. Utilizing EfficientNet as the backbone, the model optimizes parameter throughput. We adopt the ReLU activation function and utilize cosine similarity and softmax to assign weights to datasets, modifying the attention structure to reduce memory consumption. The model also integrates BiFPN for better feature extraction and employs an improved training method to enhance detection accuracy. To cater to different scenarios, we have developed four variants: FCOS_EfficientNETb0, FCOS_EfficientNETb1, FCOS_EfficientNETb2, and FCOS_EfficientNETb3. Experimental results on the MS COCO dataset show that FCOS_EfficientNETb3 achieves a mean average precision (mAP) of 48.5%, while FCOS_EfficientNETb0 reaches a frame rate of 167.17 fps, highlighting the superior performance of the series. On a custom coral bleaching detection dataset, FCOS_EfficientNETb3 achieves 81.5% accuracy and a 59.3% recall rate, demonstrating the effectiveness of the model. FCOS_EfficientNETb1 and FCOS_EfficientNETb2 offer a balance between operations per second, frame rate, and mAP, making them suitable for mobile and edge computing. These models effectively track movement or changes in marine traffic around coral reefs with moderate fps and recall rates.

Highly Diverse Symbiodiniaceae Types Hosted by Corals in a Global Hotspot of Marine Biodiversity

Symbiotic dinoflagellates in the genus Symbiodiniaceae play vital roles in promoting resilience and increasing stress tolerance in their coral hosts. While much of the world’s coral succumb to the stresses associated with increasingly severe and frequent thermal bleaching events, live coral cover in Papua New Guinea (PNG) remains some of the highest reported globally despite the historically warm waters surrounding the country. Yet, in spite of the high coral cover in PNG and the acknowledged roles Symbiodiniaceae play within their hosts, these communities have not been characterized in this global biodiversity hotspot. Using high-throughput sequencing of the ITS2 rDNA gene, we profiled the endosymbionts of four coral species, Diploastrea heliopora, Pachyseris speciosa, Pocillopora acuta, and Porites lutea, across six sites in PNG. Our findings reveal patterns of Cladocopium and Durusdinium dominance similar to other reefs in the Coral Triangle, albeit with much greater intra- and intergenomic variation. Host- and site-specific variations in Symbiodiniaceae type profiles were observed across collection sites, appearing to be driven by environmental conditions. Notably, the extensive intra- and intergenomic variation, coupled with many previously unreported sequences, highlight PNG as a potential hotspot of symbiont diversity. This work represents the first characterization of the coral-symbiont community structure in the PNG marine biodiversity hotspot, serving as a baseline for future studies.

Detection of Coral Reef Bleaching by Multitemporal Sentinel-2 Data Using the PU-Bagging Algorithm: A Feasibility Study at Lizard Island

Coral reef bleaching events have become more frequent all over the world and pose a serious threat to coral reef ecosystems. Therefore, there is an urgent need for better detection of coral reef bleaching in a time- and cost-saving manner. In recent years, remote sensing technology has often been utilized and gained recognition for coral reef bleaching detection. However, bleaching corals in the water always have weak spectral change signals, causing difficulties in using remote sensing data. Additionally, uneven change samples make it challenging to adequately capture the details of coral reef bleaching detection and produce thematic maps. To resolve these problems, a novel method named coral reef bleaching detection by positive-unlabeled bagging (CBD-PUB) is proposed in this paper. To test the capacity of the method, a series of multi-temporal Sentinel-2 remote sensing images are utilized, and Lizard Island in Australia is taken as a case study area. The pseudo-invariant feature atmospheric correction (PIF) algorithm is adopted to improve coral reef bleaching spectral signals. After that, CBD-PUB is employed to effectively explore coral reef bleaching variation and its corresponding influence relations. The experimental results show that the overall accuracy of bleaching detection by the proposed algorithm reaches 92.1% and outperforms the traditional method. It fully demonstrates the feasibility of the model for the field of coral reef bleaching detection and provides assistance in the monitoring and protection of coral environments.

Combined Role of the MJO and ENSO in Shaping Extreme Warming Patterns and Coral Bleaching Risk in the Great Barrier Reef

AbstractLocal meteorology over the Great Barrier Reef (GBR) can significantly influence ocean temperatures, which in turn impacts coral ecosystems. While El Niño–Southern Oscillation (ENSO) provides insight into the expected synoptic states, it lacks details of anticipated sub‐seasonal weather variability at local scales. This study explores the influence of the Madden‐Julian oscillation (MJO) on Australian tropical climate, both independently and in combination with ENSO, focusing on GBR impacts. We find that during El Niño periods, including the summer of 2009/10, faster propagating MJO patterns can disrupt background warm, dry conditions, and potentially provide cooling relief via increased cloud cover and stronger winds. In La Niña periods, such as the summer of 2021/22, the MJO tends to be prevented from passing the Maritime continent, forcing it to remain in a standing pattern in the Indian Ocean. This leads to decreased cloud cover and weaker winds over the GBR, generating warm ocean anomalies.

Large potential impacts of marine heatwaves on ecosystem functioning.

Ocean warming is driving significant changes in the structure and functioning of marine ecosystems, shifting species' biogeography and phenology, changing body size and biomass and altering the trophodynamics of the system. Particularly, extreme temperature events such as marine heatwaves (MHWs) have been increasing in intensity, duration and frequency. MHWs are causing large-scale impacts on marine ecosystems, such as coral bleaching, mass mortality of seagrass meadows and declines in fish stocks and other marine organisms in recent decades. In this study, we developed and applied a dynamic version of the EcoTroph trophodynamic modelling approach to study the cascading effects of individual MHW on marine ecosystem functioning. We simulated theoretical user-controlled ecosystems and explored the consequences of various assumptions of marine species mortality along the food web, associated with different MHW intensities. We show that an MHW can lead to a significant biomass reduction of all consumers, with the severity of the declines being dependent on species trophic levels (TLs) and biomes, in addition to the characteristics of MHWs. Biomass of higher TLs declines more than lower TLs under an MHW, leading to changes in ecosystem structure. While tropical ecosystems are projected to be sensitive to low-intensity MHWs, polar and temperate ecosystems are expected to be impacted by more intense MHWs. The estimated time to recover from MHW impacts is twice as long for polar ecosystems and one-third longer for temperate biomes compared with tropical biomes. This study highlights the importance of considering extreme weather events in assessing the effects of climate change on the structures and functions of marine ecosystems.