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Coral bleaching events are more frequent and severe as global temperatures rise. However, analysis of the surface energy fluxes that substantially affect the thermoregulation of shallow reef environments is rare. Previous work on evaporative cooling in a humid reef environment led to the hypothesis that in proximity to desert regions, drier air enhances evaporative cooling of water overlying coral reefs, reducing the risk of extreme high‐water temperatures. Eddy Covariance measurements made over a shallow desert fringing coral reef in the Gulf of Eilat (Israel) during summer measured evaporation of 10.3 mm d−1 which is maintaining water temperature much lower than the overlying air temperature. In addition, measurements of the most severe marine heatwave that was ever documented in the region are presented as a case study for future reference to the processes that lead to and proceed a marine heatwave, which is induced by synoptic scale events that cause a ∼50% reduction in evaporation rate. Results are compared to similar measurements from a tropical coral reef, where a lower evaporation rate suppressed by higher humidity is unable to offset the heating of water overlying the reef. We conclude that evaporative cooling is a key mechanism protecting coral reefs located in deserts from extreme high‐water temperatures, thereby representing possible thermal refugium for corals against background global warming. Plain Language Summary: We examine the energy balance between water overlying coral reefs and the atmosphere in the desert and tropical coral reefs. We hypothesize that in drier regions higher evaporation rates will cool water overlying the reefs and by that protect the corals from extreme high‐water temperatures and bleaching. We show through rare direct measurements, that the cooling of water caused by sea water evaporation is a key mechanism in mitigating extremely high‐water temperatures that can cause coral bleaching and is especially dominant in coral reefs with strong and dry winds blowing above them. The results support the hypothesis that the meteorology of regions where coral reefs fringe arid deserts provides a thermal refugium for corals against future predicted global warming. Key Points: Evaporative cooling is a key mechanism in mitigating extreme increase in water temperatures and preventing coral bleachingFollowing a marine heatwave, surface energy partitioning varies with air humidity; in drier climates evaporative cooling takes larger roleThe Gulf of Eilat (Aqaba) is identified as an evaporative thermal refugium for the preservation of coral reefs in a warming World [ABSTRACT FROM AUTHOR]

A high-precision age model is a critical component of coral skeletology. Here we propose a rapid and precise method, coupling coral growth band counting based on X-ray photo and Sr/Ca measurement using inductively coupled plasma atomic emission spectroscopy (ICP-AES) to establish the high-resolution age model. We measured Sr/Ca ratio of the Kikai coral, southeast of Japan using ICP-AES and compared the results with a previous study using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Sr/Ca values in 1947–2009 obtained by ICP-AES measurement were well correlated with Sr/Ca values obtained by LA-ICP-MS. Therefore, our study once again proved the feasibility of establishing age models by using Sr/Ca of temperate corals, and a smaller sample amount was applied for ICP-AES measurement to obtain higher-resolution data. The age model established by both Sr/Ca ratio and X-ray photo of corals will be contributed to the high-resolution coral skeletology, such as reconstructing high-resolution paleoceanography using coral skeletal radiocarbon. [ABSTRACT FROM AUTHOR]

Coral reefs are experiencing severe decline, and urgent action is required at local and global scales to curb ecosystem loss. Establishing new regulations to protect corals, however, can be time consuming and costly, and it is therefore necessary to leverage existing legal instruments, such as policies originally designed to address terrestrial rather than marine activities, to prevent coral reef degradation. Focusing on the United States, but drawing on successful examples worldwide, we present actionable pathways to increase coral protections under legislation that was originally designed to advance clean freshwater, safe drinking water, and emergency management. We identify specific legal policies and procedures (e.g., industrial permit limits, nonpoint source management incentives, and floodplain restoration programs) that can curb coral reef pollution and can be extended to other countries with similar regulations in place. Coral reef practitioners should consider a broad array of currently underused, actionable, and intersecting environmental policies that can be applied to mitigate coral stress. [ABSTRACT FROM AUTHOR]

As a typical contaminant in fossil fuels, vanadium has undergone dramatically increase due to the impacts from human activities. The excessive anthropogenic vanadium emissions have altered natural geochemical processes. However, research on vanadium geochemistry in the ocean, which is the major sink for vanadium mobilized on land, has lagged much behind relative to those of other contaminants. Here we reconstruct historical patterns of vanadium in surface seawater utilizing a high-resolution temporal record (1984–2015 CE) of geochemical proxies (vanadium/calcium (V/Ca), δ18O, δ13C, etc.) in a Porites coral colony from an offshore non-estuarine island in the northern South China Sea (SCS). We find a close association between the surface winds and the temporal patterns of coral V/Ca ratios, revealing great potential for documenting prehistoric changes in tropical cyclones. Moreover, the coral V/Ca record remarkably captured the temporal patterns of anthropogenic activities, offering a valuable and novel tool for testing the efficacy of specific legislation on pollution prevention. Combined with the other reported coral vanadium data, we recovered the historical changes in vanadium emissions in the northern SCS and identified that changing industrial practices should be responsible for the differences in anthropogenic vanadium emissions at each stage. Our results demonstrated that the coral V/Ca ratio at a high temporal resolution has great potential as a new and direct geochemical proxy for tropical cyclones after removing artificial disturbances in the ocean. [ABSTRACT FROM AUTHOR]

Rising oceanic temperatures create more frequent coral bleaching events worldwide and as such there exists a need for rapid, non-destructive survey techniques to gather greater and higher definition information than that offered by traditional spectral based monitoring systems. Here, we examine thermally induced laboratory bleaching of Montipora capricornis and Montipora confusa samples, utilising hyperspectral data to gain an understanding of coral bleaching from a spectral standpoint. The data revealed several characteristic spectral peaks that can be used to make health determinations. The fluorescence peaks are attributed to fluorescent proteins (FPs) and Chlorophyll-a fluorescence. The reflectance peaks can be attributed to Chlorophyll absorption and accessory pigments such as Peridinin and Diadinoxanthin. Each characteristic spectral peak or 'marker' allows for observation of each aspect of coral health and hence, simultaneous monitoring of these markers using hyperspectral imaging techniques provides an opportunity to better understand the processes occurring during bleaching and the rates at which they occur relative to one another. [ABSTRACT FROM AUTHOR]

Background: Symbionts provide a variety of reproductive, nutritional, and defensive resources to their hosts, but those resources can vary depending on symbiont community composition. As genetic techniques open our eyes to the breadth of symbiont diversity within myriad microbiomes, symbiosis research has begun to consider what ecological mechanisms affect the identity and relative abundance of symbiont species and how this community structure impacts resource exchange among partners. Here, we manipulated the in hospite density and relative ratio of two species of coral endosymbionts (Symbiodinium microadriaticum and Breviolum minutum) and used stable isotope enrichment to trace nutrient exchange with the host, Briareum asbestinum. Results: The patterns of uptake and translocation of carbon and nitrogen varied with both density and ratio of symbionts. Once a density threshold was reached, carbon acquisition decreased with increasing proportions of S. microadriaticum. In hosts dominated by B. minutum, nitrogen uptake was density independent and intermediate. Conversely, for those corals dominated by S. microadriaticum, nitrogen uptake decreased as densities increased, and as a result, these hosts had the overall highest (at low density) and lowest (at high density) nitrogen enrichment. Conclusions: Our findings show that the uptake and sharing of nutrients was strongly dependent on both the density of symbionts within the host, as well as which symbiont species was dominant. Together, these complex interactive effects suggest that host regulation and the repression of in hospite symbiont competition can ultimately lead to a more productive mutualism. 7h9js9xm2ik2K7FmJ48qFB Video Abstract [ABSTRACT FROM AUTHOR]

Ocean acidification (OA) is a major threat to marine calcifying organisms. This manuscript gives an overview of the physiological effects of acidification on reef-building corals from a cellular to population scale. In addition, we present the first review of the indirect effects resulting from altered species interactions. We find that the direct effects of acidification are more consistently negative at larger spatial scales, suggesting an accumulation of sub-lethal physiological effects can result in notable changes at a population and an ecosystem level. We identify that the indirect effects of acidification also have the potential to contribute to declines in coral cover under future acidified conditions. Of particular concern for reef persistence are declines in the abundance of crustose coralline algae which can result in loss of stable substrate and settlement cues for corals, potentially compounding the direct negative effects on coral recruitment rates. In addition, an increase in the abundance of bioeroders and bioerosive capacity may compound declines in calcification and result in a shift towards net dissolution. There are significant knowledge gaps around many indirect effects, including changes in herbivory and associated coral–macroalgal interactions, and changes in habitat provision of corals to fish, invertebrates and plankton, and the impact of changes to these interactions for both individual corals and reef biodiversity as structural complexity declines. This research highlights the potential of indirect effects to contribute to alterations in reef ecosystem functions and processes. Such knowledge will be critical for scaling-up the impacts of OA from individual corals to reef ecosystems and for understanding the effects of OA on reef-dependent human societies. [ABSTRACT FROM AUTHOR]

Estimating the heritable genetic variation in fitness-related traits is key to projecting the adaptive evolution of organisms in response to a changing environment. While heritability studies on reef-building corals to date support adaptive capacity, little is known about the dynamics of trait heritability across life stages in which distinct selective pressures can have long-lasting effects both within and across generations. In this study, we obtained heritability estimates for energetic and thermal stress response traits in adult, larval, and recruit Porites astreoides from two populations in the Lower Florida Keys. To induce bleaching phenotypes among individual families, larvae were exposed to a 4-day thermal stress at 32 °C, whereas adults and recruits received the same treatment for 22 days. Origin-dependent tolerance was observed in two life stages where offshore recruits lost more symbiont cells under heat than inshore recruits compared to their respective controls and heat-treated offshore adults suffered a greater loss in total protein content. Surprisingly, larvae appeared to be largely insensitive to heat regardless of origin. Broad sense heritability (H2) estimates varied greatly among traits and life stages, which may reflect changes in the relative importance of genetic and environmental variation throughout development. Over 50% of the variation in all larval traits, adult symbiont density and chlorophyll a concentration, and recruit protein content can be attributable to genetic factors. The overall moderate to high H2 estimates measured here suggest family-level variation can persist across different life stages and these corals may be equipped with considerable potential to adapt to environmental change. [ABSTRACT FROM AUTHOR]

Biodiversity of terrestrial and marine ecosystems, including coral reefs, is dominated by small, often cryptic, invertebrate taxa that play important roles in ecosystem structure and functioning. While cryptofauna community structure is determined by strong small‐scale microhabitat associations, the extent to which ecological and environmental factors shape these communities are largely unknown, as is the relative importance of particular microhabitats in supporting reef trophodynamics from the bottom up.The goal of this study was to address these knowledge gaps, provided coral reefs are increasingly exposed to multiple disturbances and environmental gradients that influence habitat complexity, condition and ecosystem functioning.We compared the density, biomass, size range, phylogenetic diversity and functional roles of motile cryptofauna in Palau, Western Micronesia, among four coral‐derived microhabitats representing various states of degradation (live coral [Acropora and Pocillopora], dead coral and coral rubble) from reefs along a gradient of effluent exposure.In total, 122 families across ten phyla were identified, dominated by the Arthropoda (Crustacea) and Mollusca. Cryptofauna biomass was greatest in live Pocillopora, while coral rubble contained the greatest density and diversity. Size ranges were broader in live corals than both dead coral and rubble. From a bottom‐up perspective, effluent exposure had mixed effects on cryptic communities including a decline in total biomass in rubble. From a top‐down perspective, cryptofauna were generally unaffected by predator biomass.Our data show that, as coral reef ecosystems continue to decline in response to more frequent and severe disturbances, habitats other than live coral may become increasingly important in supporting coral reef biodiversity and food webs. [ABSTRACT FROM AUTHOR]

Coral reefs are declining worldwide primarily because of bleaching and subsequent mortality resulting from thermal stress. Currently, extensive efforts to engage in more holistic research and restoration endeavors have considerably expanded the techniques applied to examine coral samples. Despite such advances, coral bleaching and restoration studies are often conducted within a specific disciplinary focus, where specimens are collected, preserved, and archived in ways that are not always conducive to further downstream analyses by specialists in other disciplines. This approach may prevent the full utilization of unexpended specimens, leading to siloed research, duplicative efforts, unnecessary loss of additional corals to research endeavors, and overall increased costs. A recent US National Science Foundationsponsored workshop set out to consolidate our collective knowledge across the disciplines of Omics, Physiology, and Microscopy and Imaging regarding the methods used for coral sample collection, preservation, and archiving. Here, we highlight knowledge gaps and propose some simple steps for collecting, preserving, and archiving coral-bleaching specimens that can increase the impact of individual coral bleaching and restoration studies, as well as foster additional analyses and future discoveries through collaboration. Rapid freezing of samples in liquid nitrogen or placing at -80 °C to -20 °C is optimal for most Omics and Physiology studies with a few exceptions; however, freezing samples removes the potential for many Microscopy and Imaging-based analyses due to the alteration of tissue integrity during freezing. For Microscopy and Imaging, samples are best stored in aldehydes. The use of sterile gloves and receptacles during collection supports the downstream analysis of host-associated bacterial and viral communities which are particularly germane to disease and restoration efforts. Across all disciplines, the use of aseptic techniques during collection, preservation, and archiving maximizes the research potential of coral specimens and allows for the greatest number of possible downstream analyses. [ABSTRACT FROM AUTHOR]

The largest underwater sculpture in the world, the 'Coral Greenhouse' by artist Jason deCaires Taylor, was commissioned by the Museum of Underwater Art and installed at John Brewer Reef, Australia, in December 2019. The planning process required certified engineering design drawings associated with design life, durability and suitability of materials, and baseline ecological surveys. Following approval, the operational phase required annual monitoring of substrate, ecology, social values, and marine debris. We geo-referenced three permanent transects and designed a before/after rapid monitoring assessment of substrate, fish, and invertebrates. Substrate surveys indicated 11% concrete and 89% sand. Fish surveys indicated significant increases of diversity and abundance, with 12 species and 65 individuals recorded in 2018 compared to 46 species and 365 individuals recorded in 2022. Macroinvertebrate species maintained no significant trends in abundance, species richness, and diversity with respect to time between 2018 and 2022. We monitored coral restoration and natural recruitment at the site, measuring aesthetics, survivorship of planted corals, and coral recruitment. Of 131 corals transplanted in March 2020, survivorship was 100% at 1 month, 92% at 6 months, and 91.6% at 12 months. Hard and soft corals were recruited to the structure at a density of 8.35 hard corals/m2 and 10.9 soft corals/m2 over 26 months. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) geochemical cycle plays a significant role in the composition and function of the marine ecosystem. Skeletal cadmium‐to‐calcium (Cd/Ca) ratios in hermatypic corals have been applied to reconstruct the historical changes of oceanic and climatic processes, yet there was no systematic evaluation of this tracer's natural variability in high resolution over time. Here, we reported a coral skeletal Cd/Ca record in monthly resolution from 1999 to 2008 CE and reconstructed the history of Cd contents in surface seawater in the northern South China Sea. A significant seasonal variation (higher in the winter but lower in the summer) of Cd contents in surface seawater can be identified. We found that the seasonal variations in coral skeletal Cd/Ca ratios exhibited significant trends coupled with the surface wind speeds, indicating that strong winds had likely driven the vertical seawater mixing process and then induced the process of sediment remobilization on the shelf, which significantly increased Cd contents in surface seawater. The reduction in Cd contents in surface seawater due to biological processes might be masked by the impacts of surface winds. Importantly, we also observed that coral skeletal Cd/Ca records in the winter showed significant correlations with the winter monsoon index, highlighting the possibility as a new proxy of winter monsoon in the non‐upwelling shelf environments. Plain Language Summary: Cadmium (Cd) is a nutrient element absorbed by phytoplankton in surface seawater, showing a distribution of low surface content and high bottom content. In order to determine the seasonal variations of Cd content in surface seawater in the northern South China Sea, we analyzed the coral skeletal Cd/Ca ratios in monthly resolution (1999–2008 CE) and finally concluded that the process of sediment resuspension and vertical mixing of seawater driven by winter monsoons is the main reason. The reduction of Cd contents in surface seawater due to biological processes was masked by the impacts of surface winds. In the past, Cd content in seawater/coral has been used to track the history of upwelling and El Niño Southern Oscillation, but the potential indicative on winter monsoon has not been reported so far. Considering that the trend between coral skeletal Cd/Ca ratios and average wind speeds showed a great agreement, we suggested that coral skeletal Cd/Ca ratios in the winter might be a potential proxy of winter monsoon. Key Points: Coral skeletal Cd/Ca ratios in monthly resolution were first reportedSeawater mixing process and sediments resuspension caused by winter monsoon are responsible for Cd seasonal variations in surface seawaterCoral skeletal Cd/Ca ratios have potential to be a novel proxy for winter monsoon [ABSTRACT FROM AUTHOR]

Ancient DNA (aDNA) has been applied to evolutionary questions across a wide variety of taxa. Here, for the first time, we utilized aDNA from millennia‐old fossil coral fragments to gain new insights into a rapidly declining western Atlantic reef ecosystem. We sampled four Acropora palmata fragments (dated 4215 BCE to 1099 CE) obtained from two Florida Keys reef cores. From these samples, we established that it is possible both to sequence aDNA from reef cores and place the data in the context of modern‐day genetic variation. We recovered varying amounts of nuclear DNA exhibiting the characteristic signatures of aDNA from the A. palmata fragments. To describe the holobiont sensu lato, which plays a crucial role in reef health, we utilized metagenome‐assembled genomes as a reference to identify a large additional proportion of ancient microbial DNA from the samples. The samples shared many common microbes with modern‐day coral holobionts from the same region, suggesting remarkable holobiont stability over time. Despite efforts, we were unable to recover ancient Symbiodiniaceae reads from the samples. Comparing the ancient A. palmata data to whole‐genome sequencing data from living acroporids, we found that while slightly distinct, ancient samples were most closely related to individuals of their own species. Together, these results provide a proof‐of‐principle showing that it is possible to carry out direct analysis of coral holobiont change over time, which lays a foundation for studying the impacts of environmental stress and evolutionary constraints. [ABSTRACT FROM AUTHOR]

Coral-associated actinobacteria have been abundantly reported for their biological properties, particularly as antimicrobial and anticancer agents. This study was carried out to investigate the potential of coral-associated actinobacteria as antibacterial and cytotoxic agents and analyze the biosynthetic gene clusters (BGCs) of the most remarkable isolate. Coral Porites cylindrica was collected from Menjangan Besar Island, Karimunjawa National Park, Indonesia. Based on the antibacterial screening, three out of fifteen isolates demonstrated the potential as antibacterial agents, such as CSM 11, CSM 13, and CSM 18. They were identified as Streptomyces rochei, S. xiamenensis, and S. albus, respectively. There were no crude extracts that demonstrated antibacterial activity. S. rochei CSM 11 from A11 medium showed a strong cytotoxic activity with an IC50 value of 4.50 μg/mL. The antiSMASH analysis described that S. rochei contains 33 clusters with various bioactive compounds. [ABSTRACT FROM AUTHOR]

Correctly delimiting species and populations is a prerequisite for studies of connectivity, adaptation and conservation. Genomic data are particularly useful to test species differentiation for organisms with few informative morphological characters or low discrimination of cytoplasmic markers, as in Scleractinians. Here we applied Restriction site Associated DNA sequencing (RAD-sequencing) to the study of species differentiation and genetic structure in populations of Pocillopora spp. from Oman and French Polynesia, with the objectives to test species hypotheses, and to study the genetic structure among sampling sites within species. We focused here on coral colonies morphologically similar to P. acuta (damicornis type β). We tested the impact of different filtering strategies on the stability of the results. The main genetic differentiation was observed between samples from Oman and French Polynesia. These samples corresponded to different previously defined primary species hypotheses (PSH), i.e., PSHs 12 and 13 in Oman, and PSH 5 in French Polynesia. In Oman, we did not observe any clear differentiation between the two putative species PSH 12 and 13, nor between sampling sites. In French Polynesia, where a single species hypothesis was studied, there was no differentiation between sites. Our analyses allowed the identification of clonal lineages in Oman and French Polynesia. The impact of clonality on genetic diversity is discussed in light of individual-based simulations. [ABSTRACT FROM AUTHOR]

Coral reefs are undergoing precipitous decline due to coral bleaching and disease following warming events, with impacted reefs often shifting from coral to macroalgal dominance. We reciprocally transplanted three common coral species between two pairs of coral-dominated marine-protected areas (MPAs) and adjacent macroalgal-dominated fished areas to test for the effects of reef origin and transplant area on coral defense against the common coral pathogen Vibrio coralliilyticus. For the ecologically sensitive species Acropora millepora, both reef origin and transplant area influenced the potency of defense, but for the ecologically hardy coral Porites cylindrica or the weedy coral Pocillopora damicornis, potency was not altered. A. millepora colonies that originated from, or were transplanted into, coral-dominated MPAs exhibited a 46% and 38% increase, respectively, in inhibition of V. coralliilyticus relative to those that originated from, or were transplanted into, macroalgal-dominated fished areas. A. millepora also exhibited reef origin effects on its microbial community composition, notably with persistently higher relative abundances of Vibrionaceae among individuals that originated from macroalgal-dominated fished areas compared to individuals that originated from coral-dominated MPAs. For ecologically important but disease and bleaching susceptible species like acroporids, macroalgal-dominated reefs may suppress coral defense against Vibrio pathogens and facilitate blooms of Vibrio bacteria that may harm corals during periods of thermal stress. However, their defense against Vibrio coralliilyticus recovered when not subjected to degraded reefs dominated by macroalgae. [ABSTRACT FROM AUTHOR]

Marine larval dispersal is strongly influenced by ocean currents, but larvae themselves possess traits and behaviors that can curtail or augment dispersal, and affect their settlement. Energetics and metabolism, buoyancy, and swimming can all influence the ultimate fate of marine larvae through biophysical interactions with the environment. These biophysical interactions can be difficult to observe in situ, and ecologists often resort to biophysical models to predict dispersal pathways and estimate connectivity. These models aim to assist in marine reserve design and conservation; however, larval propagules have often been modeled as passive particles, which ignores the influence of the often complex early life-history of larvae on their own dispersal. Here we provide a systematic survey of vertical larval swimming behaviors in six species of Caribbean coral larvae, throughout their early ontogeny. We deployed novel larval observation systems ex situ to obtain continuous video footage of larval vertical velocity and behavior, tracked larvae using computer vision, and calculated time-series of vertical velocity distributions. Results add depth and resolution to the dramatic contrast in swimming behaviors between brooded and broadcast spawned coral larvae. In the absence of settlement cues, brooders often settled quickly post-planulation and exhibited mainly downward swimming behaviors throughout the first two weeks of life. Though they exhibited within-cohort variation, in the absence of settlement cues broadcast spawners typically continued swimming upward even after attaining competency. Behaviors in brooded larvae suggest that there is strong pressure to settle upon planulation. However, observations of detachment and continued downward swimming suggest an active search for suitable habitat. Oppositely, broadcast larvae were observed to prolong dispersal in the absence of settlement cues. Velocity distributions obtained in this study can be used parameterize propagule behaviors in biophysical models to examine the effects of behaviors on connectivity and larval retention in high-resolution coastal hydrodynamic models. • Brooded larvae can settle and swim downward immediately upon planulation. • Most broadcast larvae continue upward swimming after attaining competency. • Maximum swimming speeds across all larvae were under 1.0 cm/s. • Montastraea cavernosa gained motility in as little as 18 h post-spawning [ABSTRACT FROM AUTHOR]

[Display omitted] • The relative thermal conductivities of carbon-based nanofluids were predicted by QSPR methodology. • Quasi-SMILES notation is used to encoding the GNPs and experimental conditions, while CORAL is used to develop models. • The results showed high concentrations, high temperatures, and high surface area had a positive effect on the thermal conductivity ratio. • In contrast, low temperatures and low surface areas had a negative effect on the target property. Heat transfer processes account for a significant portion of the world's total energy consumption, making it crucial to enhance their efficiency. Nanofluids have garnered considerable attention in this domain as a means to achieve this objective. This study focuses on investigating the impact of key variables, including temperature, concentration, and specific surface area of graphene nanoplatelets (GNPs) dispersed in distilled water, on the thermal conductivities of these nanofluids. The quantitative structure–property relationship (QSPR) methodology is employed for this analysis. The experimental conditions in preparing GNP-based nanofluid are encoded using the quasi-SMILES notation. The calculated optimal descriptors were acquired using the Monte Carlo method in CORAL software. The results of the best model indicated that the R2 m values for all splits are more than 0.5 and ΔR2 m less than 0.2. The predictive prowess and reliability of the models were substantiated by the statistical characteristics. For the best model (split 2), these values are R2 m = 0.9290 and ΔR2 m = 0.0301, which reveals the quality of the model. The created models had a clearly defined application domain, and correlation weights were calculated for all splits. The analysis of calculated correlation weights for the developed model are used to identify the main effects of experimental variables. The obtained results indicated that high concentrations, high temperatures, and high surface areas positively influenced the thermal conductivity ratio of the investigated carbon-based nanofluids. Conversely, low temperatures and low surface areas had a negative impact on the target property. [ABSTRACT FROM AUTHOR]

The Great Barrier Reef (GBR) is predicted to undergo its sixth mass coral bleaching event during the Southern Hemisphere summer of 2021-2022. Coral bleaching-level heat stress over the GBR is forecast to start earlier than any previous year in the satellite record (1985-present). The National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch (CRW) near real-time satellite-based heat stress products were used to investigate early-summer sea surface temperature (SST) and heat stress conditions on the GBR during late 2021. As of 14 December 2021, values of instantaneous heat stress (Coral Bleaching HotSpots) and accumulated heat stress over a 12-week running window (Degree Heating Weeks) on the GBR were unprecedented in the satellite record. Further, 89% of GBR satellite reef pixels for this date in 2021 had a positive seven-day SST trend of greater than 0.2 degrees Celsius/week. Background temperatures (the minimum temperature over the previous 29 days) were alarmingly high, with 87% of GBR reef pixels on 14 December 2021 being greater than the maximum SST over that same 29-day period for any year from 1985-2020. The GBR is starting the 2021-2022 summer season with more accumulated heat than ever before, which could have disastrous consequences for the health, recovery, and future of this critical reef system.

The symbiosis between cnidarians and dinoflagellates underpins the success of reef-building corals in otherwise nutrient-poor habitats. Alterations to symbiotic state can perturb metabolic homeostasis and thus alter the release of biogenic volatile organic compounds (BVOCs). While BVOCs can play important roles in metabolic regulation and signalling, how the symbiotic state affects BVOC output remains unexplored. We therefore characterised the suite of BVOCs that comprise the volatilome of the sea anemone Exaiptasia diaphana (‘Aiptasia’) when aposymbiotic and in symbiosis with either its native dinoflagellate symbiont Breviolum minutum or the non-native symbiont Durusdinium trenchii. In parallel, the bacterial community structure in these different symbiotic states was fully characterised to resolve the holobiont microbiome. Based on rRNA analyses, 147 unique amplicon sequence variants (ASVs) were observed across symbiotic states. Furthermore, the microbiomes were distinct across the different symbiotic states: bacteria in the family Vibrionaceae were the most abundant in aposymbiotic anemones; those in the family Crocinitomicaceae were the most abundant in anemones symbiotic with D. trenchii; and anemones symbiotic with B. minutum had the highest proportion of low-abundance ASVs. Across these different holobionts, 142 BVOCs were detected and classified into 17 groups based on their chemical structure, with BVOCs containing multiple functional groups being the most abundant. Isoprene was detected in higher abundance when anemones hosted their native symbiont, and dimethyl sulphide was detected in higher abundance in the volatilome of both Aiptasia-Symbiodiniaceae combinations relative to aposymbiotic anemones. The volatilomes of aposymbiotic anemones and anemones symbiotic with B. minutum were distinct, while the volatilome of anemones symbiotic with D. trenchii overlapped both of the others. Collectively, our results are consistent with previous reports that D. trenchii produces a metabolically sub-optimal symbiosis with Aiptasia, and add to our understanding of how symbiotic cnidarians, including corals, may respond to climate change should they acquire novel dinoflagellate partners.

Stable isotope ratios of Sr (88Sr/86Sr) are a novel indicator for identifying terrestrial and oceanic Sr cycling and biological processes. Here we evaluate the temperature dependence of stable Sr isotope ratios (δ88Sr) in the calcite skeletons of precious corals, known as octocorals. High-precision Sr isotope measurements by double spike thermal ionization mass spectrometry were applied to different precious corals (Corallium japonicum, Pleurocorallium elatius, P. konojoi, Corallium sp., Keratoisis sp., and Coralliidae sp.) collected from water depths of 30–1500 m in the Pacific Ocean, corresponding to annual mean water temperatures of 2.5 to 19.5°C. The precious corals showed mean δ88Sr values of 0.101 ± 0.023‰. The magnitude of Sr isotope fractionation between the skeleton and ambient seawater (Δ88Sr) is −0.291 and is about −0.1‰ lower than the value predicted from the precipitation of inorganic calcite. This fractionation is not affected by changes in skeletal Sr/Ca ratio and associated biological effects on δ88Sr are negligible. δ88Sr of precious coral skeleton is an excellent recorder of ambient seawater.

Abstract Cadmium (Cd) geochemical cycle plays a significant role in the composition and function of the marine ecosystem. Skeletal cadmium‐to‐calcium (Cd/Ca) ratios in hermatypic corals have been applied to reconstruct the historical changes of oceanic and climatic processes, yet there was no systematic evaluation of this tracer's natural variability in high resolution over time. Here, we reported a coral skeletal Cd/Ca record in monthly resolution from 1999 to 2008 CE and reconstructed the history of Cd contents in surface seawater in the northern South China Sea. A significant seasonal variation (higher in the winter but lower in the summer) of Cd contents in surface seawater can be identified. We found that the seasonal variations in coral skeletal Cd/Ca ratios exhibited significant trends coupled with the surface wind speeds, indicating that strong winds had likely driven the vertical seawater mixing process and then induced the process of sediment remobilization on the shelf, which significantly increased Cd contents in surface seawater. The reduction in Cd contents in surface seawater due to biological processes might be masked by the impacts of surface winds. Importantly, we also observed that coral skeletal Cd/Ca records in the winter showed significant correlations with the winter monsoon index, highlighting the possibility as a new proxy of winter monsoon in the non‐upwelling shelf environments.

The Great Barrier Reef (GBR) is predicted to undergo its sixth mass coral bleaching event during the Southern Hemisphere summer of 2021-2022. Coral bleaching-level heat stress over the GBR is forecast to start earlier than any previous year in the satellite record (1985-present). The National Oceanic and Atmospheric Administration (NOAA) Coral Reef Watch (CRW) near real-time satellite-based heat stress products were used to investigate early-summer sea surface temperature (SST) and heat stress conditions on the GBR during late 2021. As of 14 December 2021, values of instantaneous heat stress (Coral Bleaching HotSpots) and accumulated heat stress over a 12-week running window (Degree Heating Weeks) on the GBR were unprecedented in the satellite record. Further, 89% of GBR satellite reef pixels for this date in 2021 had a positive seven-day SST trend of greater than 0.2 degrees Celsius/week. Background temperatures (the minimum temperature over the previous 29 days) were alarmingly high, with 87% of GBR reef pixels on 14 December 2021 being greater than the maximum SST over that same 29-day period for any year from 1985-2020. The GBR is starting the 2021-2022 summer season with more accumulated heat than ever before, which could have disastrous consequences for the health, recovery, and future of this critical reef system.

The description in 1891 of the sea pen genus Gyrophyllum Studer, 1891 and also the type species G. hirondellei Studer, 1891 was based on a single colony collected in the Azores Archipelago. During the 19th and 20th centuries, the family placement of this genus became controversial as the set of morphological features present in Gyrophyllum could justify its assignation to both the families Pennatulidae Ehrenberg, 1834 and Pteroeididae Kölliker, 1880. Deliberations over this intermediate set of characters finally ended in the reunification of the genera and species of both families under Pennatulidae by principle of priority. The use of molecular sources of information based on a series of sequencing techniques presents a different but promising phylogenetic scenario in order to go further in the understanding of pennatulacean systematics. In this paper, a complementary morphological and molecular study (multiloci sequences with three mitochondrial and one nuclear markers) based mainly on newly collected material is carried out. This study re-confirms from a molecular point of view previously published results that indicate the position of Gyrophyllum as being distant from Pennatula Linnaeus, 1758 and Pteroeides Herklots, 1858 (type genera of the families Pennatulidae and Pteroeididae, respectively). This fact together with the results of a detailed morphological examination strongly supports the placement of the enigmatic genus Gyrophyllum in a separate family: Gyrophyllidae fam. nov. and resolves the nomenclatural uncertainty at family level for this genus. Moreover, the characters previously considered useful in the distinction of the two currently recognised species G. hirondellei in the Atlantic and G. sibogae Hickson, 1916 in the Indo-western Pacific are revisited.

Coral reefs are declining worldwide primarily because of bleaching and subsequent mortality resulting from thermal stress. Currently, extensive efforts to engage in more holistic research and restoration endeavors have considerably expanded the techniques applied to examine coral samples. Despite such advances, coral bleaching and restoration studies are often conducted within a specific disciplinary focus, where specimens are collected, preserved, and archived in ways that are not always conducive to further downstream analyses by specialists in other disciplines. This approach may prevent the full utilization of unexpended specimens, leading to siloed research, duplicative efforts, unnecessary loss of additional corals to research endeavors, and overall increased costs. A recent US National Science Foundation-sponsored workshop set out to consolidate our collective knowledge across the disciplines of Omics, Physiology, and Microscopy and Imaging regarding the methods used for coral sample collection, preservation, and archiving. Here, we highlight knowledge gaps and propose some simple steps for collecting, preserving, and archiving coral-bleaching specimens that can increase the impact of individual coral bleaching and restoration studies, as well as foster additional analyses and future discoveries through collaboration. Rapid freezing of samples in liquid nitrogen or placing at −80 °C to −20 °C is optimal for most Omics and Physiology studies with a few exceptions; however, freezing samples removes the potential for many Microscopy and Imaging-based analyses due to the alteration of tissue integrity during freezing. For Microscopy and Imaging, samples are best stored in aldehydes. The use of sterile gloves and receptacles during collection supports the downstream analysis of host-associated bacterial and viral communities which are particularly germane to disease and restoration efforts. Across all disciplines, the use of aseptic techniques during collection, preservation, and archiving maximizes the research potential of coral specimens and allows for the greatest number of possible downstream analyses.

Volatile organic compounds (VOCs) are constituents of marine ecosystems including coral reefs, where they are sources of atmospheric reactivity, indicators of ecosystem state, components of defense strategies, and infochemicals. Most VOCs result from sunlight-related processes; however, their light-driven dynamics are still poorly understood. We studied the spatial variability of a suite of VOCs, including dimethylsulfide (DMS), and the other dimethylsulfoniopropionate-derived compounds (DMSPCs), namely, DMSP, acrylate, and dimethylsulfoxide (DMSO), in waters around colonies of two scleractinian corals (Acropora pulchra and Pocillopora sp.) and the brown seaweed Turbinaria ornata in Mo’orean reefs, French Polynesia. Concentration gradients indicated that the corals were sources of DMSPCs, but less or null sources of VOCs other than DMS, while the seaweed was a source of DMSPCs, carbonyl sulfide (COS), and poly-halomethanes. A focused study was conducted around an A. pulchra colony where VOC and DMSPC concentrations and free-living microorganism abundances were monitored every 6 h over 30 h. DMSPC concentrations near the polyps paralleled sunlight intensity, with large diurnal increases and nocturnal decrease. rDNA metabarcoding and metagenomics allowed the determination of microbial diversity and the relative abundance of target functional genes. Seawater near coral polyps was enriched in DMS as the only VOC, plus DMSP, acrylate, and DMSO, with a large increase during the day, coinciding with high abundances of symbiodiniacean sequences. Only 10 cm below, near the coral skeleton colonized by a turf alga, DMSPC concentrations were much lower and the microbial community was significantly different. Two meters down current from the coral, DMSPCs decreased further and the microbial community was more similar to that near the polyps than that near the turf alga. Several DMSP cycling genes were enriched in near-polyp with respect to down-current waters, namely, the eukaryotic DMS production and DMS oxidation encoding genes, attributed to the coral and the algal symbiont, and the prokaryotic DMS production gene dddD, harbored by coral-associated Gammaproteobacteria. Our results suggest that solar radiation-induced oxidative stress caused the release of DMSPCs by the coral holobiont, either directly or through symbiont expulsion. Strong chemical and biological gradients occurred in the water between the coral branches, which we attribute to layered hydrodynamics.

Coral reefs are ecosystems under increasing threat from global climate change. Coral restoration is a tool for preserving the biological and ecological function of coral reefs by mitigating coral loss and maintaining the structural integrity and complexity of reefs. To generate the necessary stock for coral restoration, larger coral colonies are usually fragmented to generate smaller specimens for outplanting, taking advantage of the high regenerative ability of corals. In this study, we utilized RNA‐seq technology to understand the physiological responses of Porites lobata colonies to physical fragmentation and outplanting, which have thus far not been characterized. Our results demonstrate that P. lobata fragments undergoing physical injury recover through two distinct phases: rapid wound regeneration of the cut margins, followed by a slower growth phase that cements the colony to the substrate. Our study found rapid physiological responses to acute physical injury and outplanting in the coral host that involved significantly increased energy production, calcium homeostasis disruption, and endoplasmic reticulum (ER) stress leading to increased antioxidant expression and rates of protein turnover. Our results suggest that phosphoinositide‐mediated acute calcium homeostasis disruption stimulates wound recovery processes in response to physical injury. Symbiont gene expression revealed extremely low gene differences in response to fragmentation, growth, and outplanting. These results provide insight into the physiological mechanisms that allow for rapid wound healing and stabilization in response to physical injury in corals. [ABSTRACT FROM AUTHOR]

The symbiotic relationship between dinoflagellate algae in the family Symbiodiniaceae and scleractinian corals forms the base of the tropical reef ecosystem. In scleractinian corals, recruits acquire symbionts either "vertically" from the maternal colony or initially lack symbionts and acquire them "horizontally" from the environment. Regardless of the mode of acquisition, coral species and individual colonies harbor only a subset of the highly diverse complex of species/taxa within the Symbiodiniaceae. This suggests a genetic basis for specificity, but local environmental conditions and/or symbiont availability may also play a role in determining which symbionts within the Symbiodiniaceae are initially taken up by the host. To address the relative importance of genetic and environmental drivers of symbiont uptake/establishment, we examined the acquisition of these dinoflagellate symbionts in one to three‐month‐old recruits of Orbicella faveolata to compare symbiont types present in recruits to those of parental populations versus co‐occurring adults in their destination reef. Variation in chloroplast 23S ribosomal DNA and in three polymorphic microsatellite loci was examined. We found that, in general, symbiont communities within adult colonies differed between reefs, suggesting that endemism is common among symbiont populations of O. faveolata on a local scale. Among recruits, initial symbiont acquisition was selective. O. faveolata recruits only acquired a subset of locally available symbionts, and these generally did not reflect symbiont populations in adults at either the parental or the outplant reef. Instead, symbiont communities within new recruits at a given outplant site and region tended to be similar to each other, regardless of parental source population. These results suggest temporal variation in the local symbiont source pool, although other possible drivers behind the distinct difference between symbionts within O. faveolata adults and new generations of recruits may include different ontogenetic requirements and/or reduced host selectivity in early ontogeny. [ABSTRACT FROM AUTHOR]

The application of QSAR along with other in silico tools like molecular docking, and molecular dynamics provide a lot of promise for finding new treatments for life-threatening diseases like Type 2 diabetes mellitus (T2DM). The present study is an attempt to develop Monte Carlo algorithm-based QSAR models using freely available CORAL software. The experimental data on the α-amylase inhibition by a series of benzothiazole-linked hydrazone/2,5-disubstituted-1,3,4-oxadiazole hybrids were selected as endpoint for the model generation. Initially, a total of eight QSAR models were built using correlation intensity index (CII) as a criterion of predictive potential. The model developed from split 6 using CII was the most reliable because of the highest numerical value of the determination coefficient of the validation set (r2VAL = 0.8739). The important structural fragments responsible for altering the endpoint were also extracted from the best-built model. With the goal of improved prediction quality and lower prediction errors, the validated models were used to build consensus models. Molecular docking was used to know the binding mode and pose of the selected derivatives. Further, to get insight into their metabolism by living beings, ADME studies were investigated using internet freeware, SwissADME. [ABSTRACT FROM AUTHOR]

When coral species become extinct, their genetic resources cannot be recovered. Coral cryobanks can be employed to preserve coral samples and thereby maintain the availability of the samples and increase their potential to be restocked. In this study, we developed a procedure to determine coral species-specific requirements for cryobank freezing through determining suitable cryoprotective agents (CPAs), CPA concentrations, equilibration times, holding durations, viability rates, and cell amounts for banked coral cells, and we established the first ever coral cell cryobank. Coral cells, including supporting and gland cells, epidermal nematocysts, Symbiodiniaceae and symbiotic endoderm cells (SEC) were found from the extracted protocol. Approximately half of the corals from the experimental corals consisted of spindle and cluster cells. Gastrodermal nematocysts were the least common. The overall concentration of Symbiodiniaceae in the coral cells was 8.6%. Freezing using DMSO as a CPA was suitable for approximately half of the corals, and for the other half of species, successful cell cryopreservation was achieved using MeOH and EG. EG and DMSO had similar suitabilities for Acanthastrea, Euphyllia, Favites, Lobophyllia, Pavona, Seriatopora, and Turbinaria, as did EG and MeOH for Acropora, Echinopyllia, and Sinularia and MeOH and DMSO for Platygyra after freezing. At least 14 straws from each species of coral were cryobanked in this study, totaling more than 1884 straws (0.5 mL) with an average concentration of 6.4 × 106 per mL. The results of this study may serve as a framework for cryobanks worldwide and contribute to the long-term conservation of coral reefs. [ABSTRACT FROM AUTHOR]

Strain OCN044T was isolated from the homogenised tissue and mucus of an apparently healthy Acropora cytherea coral fragment collected from the western reef terrace of Palmyra Atoll in the Northern Line Islands and was taxonomically evaluated with a polyphasic approach. The morphological and chemotaxonomic properties are consistent with characteristics of the genus Vibrio: Gram-stain-negative rods, oxidase- and catalase-positive, and motile by means of a polar flagellum. Strain OCN044T can be differentiated as a novel subspecies based on 21 differences among chemotaxonomic features (e.g., fatty acids percentages for C12:0 and C18:1ω7c), enzymatic activities (e.g., DNase and cystine arylamidase), and carbon sources utilized (e.g., L-xylose and D-melezitose) from its nearest genetic relative. Phylogenetic analysis and genomic comparisons show close evolutionary relatedness to Vibrio tetraodonis A511T but the overall genomic relatedness indices identify strain OCN044T as a distinct subspecies. Based on a polyphasic characterisation, differences in genomic and taxonomic data, strain OCN044T represents a novel subspecies of V. tetraodonis A511T, for which the name Vibrio tetraodonis subsp. pristinus subsp. nov. is proposed. The type strain is OCN044T (= LMG 31895T = DSM 111778T). [ABSTRACT FROM AUTHOR]

Our previous study evidenced that the 3D CORAGRAF loaded with PLGA microsphere constitutes PDGF-BB can support cell attachment and proliferation and can induce an osteogenic commitment of mesenchymal stromal cells in the in vitro condition. However, how this construct can perform in pathophysiological conditions in terms of repairing critical bone defects is yet to be understood. A study was therefore conducted to investigate the regeneration potential of calvaria critical-size defects using CORAGRAF + PLGA with PDGF-BB + mesenchymal stromal cells (MSCs) in a rat model. A 5 mm critical bone defect was created on calvaria of 40 male Sprague-Dawley rats. CORAGRAF incorporated either with or without PDGF-BB and seeded with rat bone-marrow-derived MSCs was implanted at the defect region. The bone regeneration potential of implanted constructs was assessed using micro-CT imaging and histological staining in weeks 4 and 8. The micro-CT images indicated a significant closure of defects in the cranial bone of the rats treated with 3D CORAGRAF + PLGA with PDGF-BB + MSCs on week 4 and 8 post-implantation. This finding, further supported with the histology outcome where the rat cranial defect treated with CORAGRAF + PLGA with PDGF-BB + MSCs indicated neo-bony ingrowth with organized and mature bone-like morphology as compared with other groups. The previous in vitro results substantiated with our pre-clinical findings demonstrate that the combination of CORAGRAF + PLGA with PDGF-BB + MSCs could be an ideal construct to support bone regeneration in critical bone defects. Hence, this construct can be further investigated for its safety and efficacy in large animal models, or it can be skipped to human trial prior for commercialization. [ABSTRACT FROM AUTHOR]

Despite wider applications for Unmanned Aerial Vehicle (UAV) in aquatic remote sensing, frequent sun glint in UAV acquisition often results in significant data gaps. Much research exists in the development of sun glint correction methods for airborne and satellite imagery to generate accurate coral habitat maps. Conversely, little is known about an appropriate glint correction method that can also be considered as data gap in UAV. This study compared glint correction methods for filling data gaps in UAV imagery acquired from the coral-dominated Pulau Bidong island in Peninsular Malaysia. This study proposed a simple seed pixel region growing technique that can be used in glint detection and mask development. It introduces the Theil-Sen regression glint correction (TSGC) for glint correction in UAV imagery and to achieve coral composition maps with thematic details, useful for sustainable coastal management. TSGC achieved a 25.6% greater coral classification accuracy compared to the uncorrected images. [ABSTRACT FROM AUTHOR]

A previously described species and a new one belonging to the recently described sea pen genus Alloptilella Li, Zhan & Xu, 2021, are here described and illustrated based on a morphological and molecular study of materials collected in the Tasman Sea (SW Pacific) and at Puerto Rico (Caribbean Sea), respectively. The species, Alloptilella moseleyi comb. nov. (Kölliker, 1880) and Alloptilella williamsi sp. nov., are in overall agreement with the generic diagnosis of Alloptilella., based on the type species, Alloptilella splendida Li, Zhan & Xu, 2021. A single relatively large colony (55 to 95 cm in total length) is known for each of the three Alloptilella species. The transferred and the new species differ from the type species in having an opposite, rather than alternate, placement of polyp leaves along the rachis, colouration of autozooids, and mesozooids (in the case of A. moseleyi comb. nov.), and spicular features (e.g. maximum sizes in different parts of the colony, presence/absence of tentacular sclerites). Alloptilella williamsi sp. nov. is the first species of the genus recorded so far from the Atlantic Ocean, all other described species being western Pacific. A molecular comparison based on a set of concatenated sequences of four markers (three mitochondrial genes (mtMutS, ND2, and COI) and a nuclear segment (28S)) relates the species here studied to the published sequences of Alloptilella splendida, within the named Clade II of previous general phylogenetic studies on the octocoral Order Pennatulacea. Alloptilella is a monophyletic grouping, sister group of the genus Scytalium Herklots, 1858. The available molecular information of the genus Ptilella Gray, 1870, is reinforced with sequences (mtMutS, ND2 and 28S) from specimens of Ptilella inflata (Kükenthal, 1910) collected off the Namibian coast (SE Atlantic). [ABSTRACT FROM AUTHOR]

Many organisms living in the ocean create tests, shells, or related physical structures of calcium carbonate (CaCO3). As this is most often from dissolved inorganic carbon, using organisms that create calcium carbonate structures for climate research and dating purposes requires knowledge of the origin of carbon that is incorporated. Here, we give a short overview of research on marine carbonates over the last 60 years, especially that based on shell and coral samples. Both shells and corals exhibit annual growth patterns, like trees, and therefore offer possibilities for yearly resolution of past radiocarbon (14C) variations. We concentrate on their evolution in 14C dating including difficulties in determining reservoir ages as well as the possibilities they offer for archaeological dating, oceanography, calibration purposes as well as environmental research in general. [ABSTRACT FROM AUTHOR]

It is thought that the active physiological regulation of the chemistry of a parent fluid is an important process in the biomineralization of scleractinian corals. Biological regulation of calcification fluid pH (pHCF) and other carbonate chemistry parameters ([CO32−]CF, DICCF, and ΩCF) may be challenged by CO2 driven acidification and temperature. Here, we examine the combined influence of changing temperature and CO2 on calcifying fluid regulation in four common Caribbean coral species—Porites astreoides, Pseudodiploria strigosa, Undaria tenuifolia, and Siderastrea siderea. We utilize skeletal boron geochemistry (B/Ca and δ11B) to probe the pHCF, [CO32−]CF, and DICCF regulation in these corals, and δ13C to track changes in the sources of carbon for calcification. Temperature was found to not influence pHCF regulation across all pCO2 treatments in these corals, in contrast to recent studies on Indo-Pacific pocilloporid corals. We find that [DIC]CF is significantly lower at higher temperatures in all the corals, and that the higher temperature was associated with depletion of host energy reserves, suggesting [DIC]CF reductions may result from reduced input of respired CO2 to the DIC pool for calcification. In addition, δ13C data suggest that under high temperature and CO2 conditions, algal symbiont photosynthesis continues to influence the calcification pool and is associated with low [DIC]CF in P. strigosa and P. astreoides. In P. astreoides this effect is also associated with an increase in chlorophyll a concentration in coral tissues at higher temperatures. These observations collectively support the assertion that physicochemical control over coral calcifying fluid chemistry is coupled to host and symbiont physiological responses to environmental change, and reveals interspecific differences in the extent and nature of this coupling. [ABSTRACT FROM AUTHOR]

Fluorescence imaging of benthic communities is a widely used tool for determining the rate of hard coral recruitment in tropical reefs. Whilst fluorescent proteins are well-studied in scleractinian corals, less is understood about their distribution and function in other sessile reef invertebrates. This short study examines fluorescence images of benthic communities on Autonomous Reef Monitoring Structures (ARMS) from a remote and protected Indian Ocean reef system. We compare the abundance of adult and juvenile hard corals across three sites and between the topside and underside of ARMS recruitment plates. We also discuss observations of skeletal fluorescence in sponges, as well as uneven green fluorescent protein (GFP) concentrations across adult coral colonies. Our findings provide an insight into the recovery of shallow reefs previously hit by severe bleaching events and highlight the potential of ARMS fluorescence imaging for the analysis of cryptobenthic communities. [ABSTRACT FROM AUTHOR]

High-latitude reefs are suboptimal coral habitats, but such habitats are increasingly considered to be potential refugia from climate change for range-shifting coral reef species. Notably, tropical reef fish have been observed along the south-east coast of Australia, but their establishment on temperate rocky reefs is currently limited by winter minimum temperatures and other resource needs, such as structurally complex habitats typical of tropical reefs. Recent expansion of the branching subtropical coral Pocillopora aliciae in rocky reefs near Sydney (34° S) could diversify the architectural structure of temperate marine environments, thereby providing potential shelter for tropical reef taxa in warming seas. Here, we investigated whether future environmental conditions (i.e. temperature increase) can influence the dominance of the subtropical branching coral P. aliciae over the resident encrusting coral Plesiastrea versipora in coastal Sydney by characterising physiological (e.g. metabolic stability) and behavioural (e.g. interspecific competitive hierarchy) traits that contribute to their competitive fitness. Our results suggest that a metabolic response, mediated by sterol and lipid metabolic pathways and provision of antioxidants, allows P. aliciae to reduce cellular stress and withstand exposure to short-term increased temperature. Conversely, P. versipora was more susceptible to heat exposure with no metabolic mediation observed. While P. versipora displayed greater aggressive behaviour when in direct contact with P. aliciae under all temperature conditions, the superior physiological and metabolic flexibility under increased temperatures of P. aliciae suggests that this species will likely outperform P. versipora under future increased temperatures. Such contrasting responses to environmental change would facilitate shifts in coral community and functional composition that could support further tropicalisation of coastal New South Wales. [ABSTRACT FROM AUTHOR]

Investigation of the association between microbial communities in different compartments and the health status of coral hosts will support an in-depth understanding of the relationship between the microbial symbionts and coral health. In this study, next-generation sequencing of 16S ribosomal RNA genes (rDNA) and ribosomal RNA (rRNA) was used to characterize bacterial communities from the mucus and tissues of healthy and bleached Pocillopora damicornis. The cDNA (active bacterial members) and DNA (the total bacterial community) libraries of the same coral sample were similar, suggesting the fact that the bacteria inhabiting P. damicornis were active. Upon coral bleaching, the bacterial communities changed considerably in the tissue, but remained stable in the coral mucus layer. The relative abundance of Endozoicomonas decreased sharply in the bleached coral tissue. Presumably, microbial function based on the taxonomic compositions was accordingly changed in coral tissue, but not in the mucus layer, when the coral bleached. This study suggests that both rRNA- and rDNA-based methods for bacterial community analysis are fit for evaluating P. damicornis health implications. Furthermore, the results of this study demonstrate the differential responses of mucus- and tissue-associated bacterial communities to coral bleaching. [ABSTRACT FROM AUTHOR]

Prior to transitioning to a coral diet, juvenile Acanthaster cf. solaris, the Crown-of-Thorns Seastar (COTS), feed on crustose coralline algae. Although a detailed understanding of juvenile ecology is crucial to predict and prevent outbreaks, the exact timing of the transition is unresolved. Two experiments were conducted to measure time and size of COTS at the transition, and investigate potential modulating effects of different coral species. COTS began early transitions at similar sizes (7.5–8.5 mm), and these first transitions were observed around 136–145 d. Between 175 and 191 d, a 50% transition in the presence of Acropora tenuis was measured. After 175d, the percentage of COTS cohorts that had transitioned was significantly lower in A. millepora (38%) and Stylophora pistillata (7%) compared to A. tenuis (51%). These data fill important knowledge gaps in juvenile ecology, and the influence of coral species on transition suggests an undescribed feedback mechanism between prey and predator. [ABSTRACT FROM AUTHOR]

To survive in nutrient-poor waters corals rely on a symbiotic association with intracellular microalgae. However, increased sea temperatures cause algal loss—known as coral bleaching—often followed by coral death. Some of the most compelling evidence in support of the 'oxidative stress theory of coral bleaching' comes from studies that exposed corals, cultures of their algal endosymbionts, or the coral model Exaiptasia diaphana to exogenous antioxidants during thermal stress. Here, we replicate these experiments using E.diaphana with the addition of the antioxidants ascorbate + catalase, catechin, or mannitol under ambient and elevated temperatures along with an antioxidant-free control. In the absence of exogenous antioxidants, E.diaphana exposed to elevated temperatures bleached with no change in reactive oxygen species (ROS) levels associated with their microalgal cells. Ascorbate + catalase and mannitol treatments rescued the anemones from bleaching, although microalgal ROS levels increased in these antioxidant treatments under elevated temperature conditions. While bleaching was not associated with changes in net ROS for the intracellular algal symbionts, it is evident from our findings that excess ROS is connected to the bleaching phenotype as exogenous antioxidants were successful in mitigating the effects of thermal stress in cnidarians. This understanding may assist applied research that aims to reduce the impact of climate change on coral reefs. [ABSTRACT FROM AUTHOR]

Recent interest in assessing coral reef functions has raised questions about how carbonate production rates have altered over the past few decades of ecological change. At the same time, there is growing interest in quantifying carbonate production on larger reef-scales. Resolving these issues is challenging because carbonate production estimates require three-dimensional survey data, which are typically collected in-situ over small spatial scales. In contrast, data that can be extracted from archive photograph or video imagery and high-resolution aerial imagery are generally planar. To address this disconnect, we collected data on the relationship between linear planar and 3D contour lengths of 62 common Indo-Pacific hard coral genera-morphotypes to establish appropriate conversion metrics (i.e. coral class rugosity values, hereafter termed Rcoral). These conversion values allow planar colony dimensions to be converted to estimates of 3D colony contour length, which can be employed within existing census budget methodologies like ReefBudget to estimate coral carbonate production (G, in kg CaCO3 m−2 yr−1). We tested this approach by comparing in-situ carbonate production data collected using the ReefBudget methodology against estimates derived from converted colony length data from video imagery. The data show a high level of consistency with an error of ~ 10%. We then demonstrate potential applications of the conversion metrics in two examples, the first using time-series (2006 to 2018) photo-quadrat imagery from Moorea, and the second using high-resolution drone imagery across different reef flat habitats from the Maldives. Whilst some degree of error must necessarily be accepted with such conversion techniques, the approach presented here offers exciting potential to calculate coral carbonate production: (1) from historical imagery to constrain past coral carbonate production rates; (2) from high quality aerial imagery for spatial up-scaling exercises; and (3) for use in rapid photograph or video-based assessments along reef systems where detailed surveys are not possible. [ABSTRACT FROM AUTHOR]