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Coral skeleton δ13C is a routinely measured indicator in modern insolation change research, but the knowledge of environmental and climatic signals recorded in its seasonality during geological time is sparse. In this study, we present eight Porites coral δ13C records from the mid‐late Holocene to the present from the northern South China Sea (NSCS). Compared with the main control factors for modern δ13C changes, coral δ13C seasonality in the NSCS since the mid‐Holocene shows a long‐term decreasing trend, which is consistent with the change trend as orbital‐induced (precession) insolation seasonal amplitude. By excluding other influencing factors, we speculate that the stronger coral δ13C seasonality (18.8%) over the mid‐Holocene than modern period is attributable to the metabolic effect, which predicts the stronger coral δ13C seasonality under stronger insolation seasonality. Our study has implications for coral δ13C seasonality as a potential indicator to record past insolation information under different climatic backgrounds. Plain Language Summary: Numerous studies have documented the seasonal features of fast‐growing modern coral skeleton δ13C in response to insolation variation. The environmental and climatic signals recorded by coral δ13C seasonality in the geological period remain unclear owing to the relatively short length of observation records. Here we present monthly resolved δ13C records in seven fossil Porites corals (5.6–3.6 ka BP, before 1950 CE) and one modern Porites coral (1987–2001 CE) from the northern South China Sea (NSCS). Compared with the widely accepted prevailing control factors for modern coral δ13C, our results indicated that the stronger coral δ13C seasonality (18.8%) over the mid‐Holocene compared to the modern period is consistent with the orbital‐induced (precession) insolation changes, which indicate a declining seasonality from the mid‐Holocene to present. By excluding other influencing factors, we infer that a tendency toward higher δ13C seasonality during the mid‐Holocene was primarily driven by the metabolic fractionation caused by the enhanced insolation seasonality. This study highlighted coral δ13C seasonality as a potential indicator for recording past insolation information. Key Points: The seasonal variation of modern coral skeleton δ13C in the northern South China Sea (NSCS) is primarily controlled by solar insolationCoral δ13C seasonality in the NSCS since the mid‐Holocene shows a long‐term decreasing trendThe decrease of orbital‐induced (precession) insolation seasonal amplitude led to the declining trend of δ13C seasonality [ABSTRACT FROM AUTHOR]

Keywords: coral holobiont; physiological regulation; homeostasis; heat stress; nutrient; microbiome; Symbiodiniaceae; bleaching EN coral holobiont physiological regulation homeostasis heat stress nutrient microbiome Symbiodiniaceae bleaching 1 4 4 05/12/22 20220510 NES 220510 Scleractinian corals form the biological and physical framework for the most productive marine ecosystem in the oligotrophic oceans and play an important role in oceanographic processes ([3]). This paper provides further evidence that corals and their associated Symbiodiniaceae and bacteria communities engage in highly coordinated metabolic interactions that are crucial for coral holobiont health, homeostasis, and heat tolerance. Data further showed that coral-associated diazotrophs were common among coral demonstrate the potential importance of N SB 2 sb -fixing bacteria as the source of N-nutrient for corals, which live in the oligotrophic environment. These factors have important effects on coral holobionts tolerance; however, there are some differences between regions, coral species and even coral individuals ([26]; [27]; [29]). [Extracted from the article]

Ocean acidification is one of many stressors that coral reef ecosystems are currently contending with. Thus, understanding the response of key symbiotic microbes to ocean acidification is of great significance for understanding the adaptation mechanism and development trend of coral holobionts. Here, high-throughput sequencing technology was employed to investigate the coral-associated bacteria and Symbiodiniaceae of the ecologically important coral Acropora valida exposed to different pH gradients. After 30 days of acclimatization, we set four acidification gradients (pH 8.2, 7.8, 7.4, and 7.2, respectively), and each pH condition was applied for 10 days, with the whole experiment lasting for 70 days. Although the Symbiodiniaceae density decreased significantly, the coral did not appear to be bleached, and the real-time photosynthetic rate did not change significantly, indicating that A. valida has strong tolerance to acidification. Moreover, the Symbiodiniaceae community composition was hardly affected by ocean acidification, with the C1 subclade (Cladocopium goreaui) being dominant among the Symbiodiniaceae dominant types. The relative abundance of the Symbiodiniaceae background types was significantly higher at pH 7.2, indicating that ocean acidification might increase the stability of the community composition by regulating the Symbiodiniaceae rare biosphere. Furthermore, the stable symbiosis between the C1 subclade and coral host may contribute to the stability of the real-time photosynthetic efficiency. Finally, concerning the coral-associated bacteria, the stable symbiosis between Endozoicomonas and coral host is likely to help them adapt to ocean acidification. The significant increase in the relative abundance of Cyanobacteria at pH 7.2 may also compensate for the photosynthesis efficiency of a coral holobiont. In summary, this study suggests that the combined response of key symbiotic microbes helps the whole coral host resist the threats of ocean acidification. [ABSTRACT FROM AUTHOR]

Coral reef ecosystems cannot operate normally without an effective nitrogen cycle. For oligotrophic coral reef areas, coral-associated diazotrophs are indispensable participants in the nitrogen cycle. However, the distribution of these diazotrophs and the correlation with the physical and chemical variables of the surrounding seawater remain unclear. To this end, 68 scleractinian coral colonies were sampled from 6 coral reef areas with different environmental variables in the South China Sea to investigate the composition of associated diazotrophs based on nifH gene amplification using high-throughput sequencing. The six coral reefs can be clearly divided into two types (fringing reefs and island reefs), are affected by varying degrees of human activities and are located at different latitudes from 9°20'06"N to 22°34'55"N with different seawater temperatures. Alpha- and beta-diversity analyses showed that the distribution of diazotrophs among coral reefs exhibited significant geographical fluctuations (p ≤ 0.05) and non-significant interspecific fluctuations (p > 0.05). The predominant bacterial phyla included Proteobacteria, Chlorobi, Cyanobacteria, and two unclassified phyla. Chlorobi exhibited a relative abundance of 47–96% in coral samples from the high-latitude Daya Bay fringing reef affected by eutrophication. Unclassified bacteria II, with a relative abundance of 28–87%, was found in all coral samples from the midlatitude Luhuitou fringing reef affected by eutrophication. However, unclassified bacteria I and Proteobacteria dominated (>80% relative abundance) in most of the coral samples from the Weizhou Island fringing reef, which is far from land, and three island reefs (Huangyan Island, Xinyi Reef, and Sanjiao Reef) at relatively low latitudes. At the genus level, some core diazotrophs were found in different coral sample groups. In addition, correlation analysis with various environmental variables revealed that the variables were positively or negatively correlated with different diazotrophic genera. Coral-associated diazotrophs were common among coral individuals. However, their composition was closely related to the different environmental variables. These results provide insights into the geographical distribution characteristics of coral-associated diazotrophs and their evolutionary trends in response to environmental change in the South China Sea. [ABSTRACT FROM AUTHOR]

Coral reefs are continuing to decline worldwide due to anthropogenic climate change. The study of the molecular diversity and biogeographical patterns of Symbiodiniaceae, is essential to understand the adaptive potential and resilience of coral–algal symbiosis. Next generation sequencing was used to analyze the Symbiodiniaceae rDNA internal transcribed spacer 2 marker genes from 178 reef-building coral samples in eight coral habitats across approximately 13° of latitude in the South China Sea (SCS). A total of three Symbiodiniaceae genera, Cladocopium , Durusdinium , and Gerakladium , as well as 31 dominant Symbiodiniaceae types, were identified. Symbiodiniaceae richness, diversity, and community composition varied according to latitude; intermediate and low latitude coral reefs (IR and LR) have higher Symbiodiniaceae richness and diversity than high latitude coral habitats (HC and HR). A PERMANOVA analysis found significant differences in the Symbiodiniaceae community composition in the SCS (F = 14.75, R 2 = 0.20, p = 0.001 < 0.01). The major dominant Symbiodiniaceae types were C1 in the HC and the HR, C1/Cspc/C50/C15 and D1 in the IR, and C3u and C15 in the LR. Canonical correspondence analysis showed that the relative abundance of different Symbiodiniaceae types is affected by multiple environmental factors. Phylogenetic analysis indicated that the Symbiodiniaceae type Cladocopium , which shared common ancestors, shows similar environmental adaptability. Based on these results, we suggest that coral host species played a relatively small role in the identity of the dominant Symbiodiniaceae type. Therefore, the biogeographical patterns of Symbiodiniaceae may be mainly affected by environmental factors. Our research provides a comprehensive overview of the biogeography of Symbiodiniaceae in the SCS, where coral communities and reefs are widely distributed across different latitude regions and have variable environmental conditions. Our data will provide support for further study of the regional diversification of Symbiodiniaceae and the ecological resilience of the coral-Symbiodiniaceae symbioses. [ABSTRACT FROM AUTHOR]

In this study, the contamination levels and seasonal variation of 22 PFASs were investigated in coastal reef-building corals (n = 68) from the northern South China Sea (SCS) during wet and dry seasons. Perfluorohexane sulfonate (PFHxS) was the predominant PFASs in all coral samples, representing 43% of the total PFAS. Long-chain PFASs, as well as PFAS alternatives, were frequently detected above the MQL (>88%) but showed relatively low concentrations compared to short-chain PFASs in most species and seasons. Seasonal variation of PFAS concentrations were observed in branching corals, indicating that the accumulation of PFASs may be associated with coral morphological structures. Interspecies differences in PFAS levels agree well with different bioaccumulation potentials among coral species. Redundancy analysis (RDA) showed that seasonal factor and coral genus could partly influence PFAS concentrations in coral tissues. In summary, our study firstly reported the occurrence of PFASs in coral communities from the SCS and highlights the necessity for future investigations on more toxicity data for coral communities. [Display omitted] • This is the first study about PFAS occurrence in coral reef ecosystem. • PFHxS was the predominant PFAS in all coral species. • Short-chain PFASs presented low detection frequencies but relatively high levels. • Branching species are particularly susceptible to PFAS exposure. • Seasonal factor and coral genus have certain effects on the accumulation of PFASs. [ABSTRACT FROM AUTHOR]

Coral ingestion by crown-of-thorns starfish (COTS) is an important cause of coral reef degradation, although the impacts of COTS feeding on coral-associated microbial communities are not well understood. Therefore, in this study, we analyzed the coral tissue-weight, Symbiodiniaceae density (SD), bacterial community composition, and the predicted functions of bacterial genes associated with Pocillopora corals in healthy portions and feeding scars, following COTS feeding. Coral tissue-weight loss rate in the feeding scars was 71.3–94.95%. The SDs were significantly lower in the feeding scars, and the SD-loss rate was 92.05% ± 2.12%. The relative abundances of bacterial communities associated with Pocillopora corals after COTS feeding changed significantly and were almost completely reorganized at the phylum and genus levels. Analysis of the microbial metagenomic-functional capacities showed that numerous physiological functions of the coral-bacterial holobionts in the feeding scars were different, including amino acid metabolism, xenobiotic biodegradation and metabolism, lipid metabolism, membrane transport, signal transduction, and cell motility, and all these capacities could be corroborated based on metagenomic, transcriptomic or proteomic technologies. Overall, our research suggests that coral holobionts may be destroyed by COTS, and our findings imply that bacterial communities in feeding scars could affect the health of Pocillopora corals. [ABSTRACT FROM AUTHOR]

Ciguatera poisoning is mainly caused by the consumption of reef fish that have accumulated ciguatoxins (CTXs) produced by the benthic dinoflagellates Gambierdiscus and Fukuyoa. China has a long history of problems with ciguatera, but research on ciguatera causative organisms is very limited, especially in the Beibu Gulf, where coral reefs have been degraded significantly and CTXs in reef fish have exceeded food safety guidelines. Here, five strains of Gambierdiscus spp. were collected from Weizhou Island, a ciguatera hotspot in the Beibu Gulf, and identified by light and scanning electron microscopy and phylogenetic analyses based on large and small subunit rDNA sequences. Strains showed typical morphological characteristics of Gambierdiscus caribaeus, exhibiting a smooth thecal surface, rectangular-shaped 2′, almost symmetric 4″, and a large and broad posterior intercalary plate. They clustered in the phylogenetic tree with G. caribaeus from other locations. Therefore, these five strains belonged to G. caribaeus, a globally distributed Gambierdiscus species. Toxicity was determined through the mouse neuroblastoma assay and ranged from 0 to 5.40 fg CTX3C eq cell−1. The low level of toxicity of G. caribaeus in Weizhou Island, with CTX-contaminated fish above the regulatory level in the previous study, suggests that the long-term presence of low toxicity G. caribaeus might lead to the bioaccumulation of CTXs in fish, which can reach dangerous CTX levels. Alternatively, other highly-toxic, non-sampled strains could be present in these waters. This is the first report on toxic Gambierdiscus from the Beibu Gulf and Chinese waters and will provide a basis for further research determining effective strategies for ciguatera management in the area. [ABSTRACT FROM AUTHOR]

Global warming and sea-level rise (SLR) induced by rising atmospheric CO2 concentrations can cause coral bleaching, death, and submergence of the world's coral reefs. Adopting the GIS and RS methods, we modeled how these two stressors combine to influence the future growth of the atolls and table reefs of three archipelagoes in the South China Sea (SCS), based on geomorphic and ecological zones. A large-scale survey of the coral communities in Xisha Islands in 2014, Dongsha Islands in 2014–2016 and Nansha Islands in 2007 provided zone-specific process datasets on the range of reef accretion rates. Sea surface temperature and extreme (minimum and maximum) SLR data above 1985–2005 levels by 2100 in the SCS were derived from the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) models forced with the Representative Concentration Pathways (RCPs). Our model projected that: (1) the Xisha Islands and Dongsha Islands may have a better growth status, because the reef flat biotic sparse zone may be recolonized with hard coral and become a biotic dense zone; (2) the southern Nansha Islands reefs have a risk of stopping growing due to their earlier annual bleaching years. The increasing of water depths of these reefs is stronger in the RCP with more emissions. Our approach offers insights into the best-case and worst-case impacts of two global environmental pressures on potential future reef growth under a changing climate. [ABSTRACT FROM AUTHOR]

Relatively high-latitude waters are supposed as a refuge for corals under ocean warming. A systematic assessment of the Weizhou Island reef in the northern South China Sea, a relatively high-latitude region, shows that the ecosystem restoration index decreased from 0.96 to 0.62 during the period between 1990 and 2015. Although the biotic community, supporting services, and regulating services remained at good or very good states, the provisioning services, cultural services, and especially habitat structure deteriorated to very poor or moderate states. Gray relational analysis showed that these ecological declines exhibited a strong relationship with human pressures from tourism activities and the petrochemical industry. The recoveries of the biotic community and supporting services that benefited from wintertime warming appeared to be partly offset by intensive human pressures. The long-term effects on ecosystem structure and functions suggest that anthropogenic disturbances have impaired the possibility of this area serving as a potential thermal refuge for reef-building corals in the South China Sea. This study thus provides an integrated approach for assessing the adaptive responses of coral reef ecosystems to climate change and local human activities. [ABSTRACT FROM AUTHOR]

Coral reefs are important as they can help to maintain ecological balance, biological resources, and species diversity on earth. However, they are globally threatened by human activities and climate change. As live coral cover (LCC) is regarded as an important measure of the health of coral reefs, analysis on LCC change associated with environmental parameters, such as chlorophyll-a concentration (Chl-a), sea surface temperature (SST), and photosynthetically active radiation (PAR), is of great value. Research on this front would help us comprehend the changes in coral reefs induced by human activities and global changes. Instead of using spasmodically in-field-measured environmental parameters, in this study, we chose to combine the successive Chl-a, SST, and PAR products of the Moderate Resolution Imaging Spectroradiometer (MODIS) with historic LCC records to establish an empirical relationship using nonlinear optimization. Thereafter, the established relationship was further used to discuss some possible developments of LCCs. According to the experiments, we concluded that the degradation of the LCC around Weizhou Island may be mainly caused by human-activity-caused eutrophication. Besides, we also showed that even if the Chl-a and the PAR can keep constant with current average levels, the corals around Weizhou Island may still be in a risk of disappearing between 2120–2140 as the SST continues to rise. [ABSTRACT FROM AUTHOR]

Despite organophosphate esters (OPEs) are widely prevalent in the environment, however, limited information is available regarding their occurrence, trophodynamics, and exposure risks in coral reef ecosystems. In this study, 11 OPEs were investigated in a tropical marine food web (7 fish species and 9 benthos species) from the Xisha (XS) Islands, South China Sea (SCS). The ∑ 11 OPEs were 1.52 ± 0.33 ng/L, 2227 ± 2062 ng/g lipid weight (lw), 1024 ± 606 ng/g lw, and 1800 ± 1344 ng/g lw in seawater, fish, molluscs, and corals, respectively. Tris (2-chloroisopropyl) phosphate (TCIPPs) were the dominant OPEs in seawater, fish, and molluscs, while tris (2-butoxyethyl) phosphate (TBOEP) predominated in coral tissues. Abiotic and biotic factors jointly affect the OPEs enrichment in marine organisms. Trophic magnification factors (TMFs) (range: 1.31–39.2) indicated the biomagnification potency of OPEs. A dietary exposure risk assessment indicated that OPEs at current levels in coral reef fish posed a low risk to human health but were not negligible. Overall, this study contributes to a further understanding of the environmental behaviors of OPEs in coral reef ecosystems. [Display omitted] • OPEs profiles in seawater and marine organisms are different. • Fish tend to enrich Cl-alkyl OPEs and benthos prefer to accumulate aryl OPEs. • Abiotic and biotic factors jointly affect the OPEs enrichment in marine organisms. • OPEs pose a low risk to human health by coral reef fish ingestion. • Emerging pollutants are dominating the pollution status in the Xisha Islands. [ABSTRACT FROM AUTHOR]

Recent studies have indicated that coral mucus plays an important role in the bioaccumulation of a few organic pollutants by corals, but no relevant studies have been conducted on organochlorine pesticides (OCPs). Previous studies have also indicated that OCPs widely occur in a few coral reef ecosystems and have a negative effect on coral health. Therefore, this study focused on the occurrence and bioaccumulation of a few OCPs, such as dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzene (HCB) and p , p ′-methoxychlor (MXC), in the coral tissues and mucus as well as in plankton and seawater from a coastal reef ecosystem (Weizhou Island) in the South China Sea. The results indicated that DDTs were the predominant OCPs in seawater and marine biota. Higher concentrations of OCPs in plankton may contribute to the enrichment of OCPs by corals. The significantly higher total OCP concentration (∑ 8 OCPs) found in coral mucus than in coral tissues suggested that coral mucus played an essential role in resisting enrichment of OCPs by coral tissues. This study explored the different functions of coral tissues and mucus in OCP enrichment and biodegradation for the first time, highlighting the need for OCP toxicity experiments from both tissue and mucus perspectives. [Display omitted] • OCPs were firstly studied in coral mucus in the South China Sea. • Plankton may have an influence on coral enrichment of OCPs. • Obvious higher ∑ 8 OCPs occurred in coral mucus than in coral tissues. • Coral mucus showed lower metabolic capability of DDTs than coral tissues. • Coral mucus may resist the enrichment and metabolism of OCPs by coral tissues. [ABSTRACT FROM AUTHOR]

The levels, fate, and potential sources of 22 organochlorine pesticides (OCPs) in coral tissues and the surrounding air-seawater system from the South China Sea (SCS) were elucidated for the first time. ∑ 22 OCPs (total concentration of 22 OCPs) (16.1–223 pg L−1) was relatively higher in coastal seawater than in offshore seawater, which may be the widespread influence of coastal pollution inputs under the western boundary current. The atmospheric ∑ 22 OCPs were predominantly distributed in the gas phase (48.0–2264 pg m−3) and were mainly influenced by continental air mass origins. The air-seawater exchange of selected OCPs showed that OCPs tended to migrate from the atmosphere to seawater. The distribution of ∑ 22 OCPs in coral tissues (0.02–52.2 ng g−1 dw) was significantly correlated with that in air samples, suggesting that OCPs may have a migration pattern of atmosphere-ocean corals in the SCS. Corals exhibited higher bioaccumulation ability (Log BAFs : 2.42–7.41) for OCPs. Source analysis showed that the new application of technical Chlordanes (CHLs) was primarily responsible for the current levels of CHLs in the surrounding environment over the SCS, while historical residues were the primary sources of other OCPs. [Display omitted] • Pioneer OCPs study of coral tissues from the South China Sea (SCS). • Corals presented a higher bioaccumulative ability to OCPs. • Ocean currents and monsoons played essential roles in the OCPs' spatial distribution. • Net atmospheric deposition of OCPs occurred in the coral reef regions (CRRs), SCS. • OCPs may have a migration pattern of atmosphere-ocean-corals in the CRRs, SCS. [ABSTRACT FROM AUTHOR]

Coral probiotics can improve the tolerance of corals to heat stress, thus mitigating the process of coral thermal bleaching. Sensitive and specific detection of coral probiotics at low abundances is highly desirable but remains challenging, especially for rapid and on-site detection of coral probiotics. Since the electrochemical biosensor has been recently used in the field of environmental DNA (eDNA) detection, herein, an efficient electrochemical biosensor was developed based on CoS 2 /CoSe 2 -NC HNCs electrode material with a specific DNA probe for the C. marina detection. After optimization, the lower limit of detection (LOD) values of such biosensors for the target DNA and genomic DNA were 1.58 fM and 6.5 pM, respectively. On this basis, a portable device was constructed for the practical detection of C. marina eDNA, and its reliability and accuracy were verified by comparison with the ddPCR method (P > 0.05). For each analysis, the average cost was only ∼ $1.08 and could be completed within 100 min with reliable sensitivity and specificity. Overall, the biosensor could reflect the protective effect of probiotics on coral heat stress, and the proposed technique will put new insights into the rapid and on-site detection of coral probiotics to assist corals against global warming. [ABSTRACT FROM AUTHOR]

[Display omitted] • Blue light increases the thermal bleaching tolerance of coral holobiont. • Blue light decreases photosynthesis, respiration and ROS release of Symbiodiniaceae under heat stress. • Blue light reduces respiration and lipid peroxidation of host under heat stress. • The up-regulation of the DAO gene indicates a coral bleaching model that dependents on the host. Given the high degree of heterogeneity of coral bleaching, there is potential for abiotic approaches to improve the thermal tolerance of coral. However, there is limited knowledge about such factors and causes that regulating acclimation of coral to warming. Here, a study was conducted on the reef building coral Acropora tenuis to investigate the impact of light qualities on the physiological, cellular, and molecular biochemical responses of the coral holobiont to heat stress. The results showed that after subjecting the samples to heat stress at 32 ℃ for 9 days, over 90% corals exposed to compound light experienced bleaching on the fifth day, while corals exposed to blue light showed no significant signs of bleaching even on the ninth day. This indicates that blue light may enhanced the coral's thermal bleaching tolerance. Further analysis revealed blue light primarily increased coral's resistance to thermal bleaching by remodeling the interactions between Symbiodiniaceae (i.e. decreased photosynthesis, respiration and ROS release) and coral (i.e. decreased respiration and lipid peroxidation). The study also found that the host's of reactive oxygen species (ROS) played a role in causing coral bleaching besides the ROS released by Symbiodiniaceae. The up-regulation of the DAO gene (encoding D-amino-acid oxidase, up-regulated nearly 1000 times under warming conditions) in the host highlights the mechanism of coral bleaching, whereby the catalysis of amino acids by the D-amino-acid oxidase produces ROS. In summary, the present study reveals novelty insights into the molecular processes related to thermal bleaching of coral, identifies blue light as a positive environmental factor that enhances coral's tolerance to global warming. [ABSTRACT FROM AUTHOR]

Multiple environmental pressures caused by global warming and human activities have aroused widespread concern about PAHs pollution in tropical marine coral reef regions (CRRs). However, the trophodynamics of PAHs in the food webs of the CRRs and the related influence factors have not been reported. This study investigated the occurrence, trophic amplification, and transmission of PAHs in various organisms selecting between at least representative species for each level in CRRs of the South China Sea (SCS); revealed their driving mechanisms; and explored the trophodynamics of PAHs in the food web of the coral reef ecosystem. Results showed that more PAHs can be accumulated in the mantle tissue of Tridacnidae, and the proportion of mantle tissue of Tridacnidae increases with the increase of latitude (y = 0.01x + 0.17, R2 = 0.49, p < 0.05). Latitude drives the differential occurrence level and bioaccumulation of PAHs in tropical marine organisms, and also affects the trophodynamics of PAHs in aquatic ecosystem food webs. PAHs undergo trophic amplification in the food webs of tropical marine ecosystems represented by coral reefs, thus further aggravating the negative environmental impact on coral reef ecosystems. The cancer risk caused by accidental ingestion of PAHs by humans through consumption of seafood in CRRs is very low, but we should be alert to the biomagnification effect of PAHs. [Display omitted] • Reported PAHs' occurrence in the coral reef food web for the first time. • Latitude affected PAHs' occurrence and bioaccumulation in the organisms. • Latitude drove the PAHs' trophodynamics in aquatic ecosystem food webs. • PAHs underwent trophic amplification in the food webs of coral reef ecosystems. [ABSTRACT FROM AUTHOR]

Widespread coral bleaching and mortality has occurred intensively and frequently under global warming conditions since the phenomenon was first documented in the early 1980s. However, abrupt and extensive mortality episodes, such as which occurred in the South China Sea (SCS) in mid-1991, cannot be explained solely on the basis of high summer sea surface temperatures. Here we examine this event in the light of time series rare earth elements, trace element Al/Ca ratios, and micro-domain images from coral samples collected in the SCS region. Results demonstrate that modern coral reefs were strongly imposed by a giant volcanic eruption, the 1991 Mount Pinatubo volcanic eruption. Our findings highlight that contemporary continental near-shore reefs are more susceptible than their open-ocean counterparts. [ABSTRACT FROM AUTHOR]