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How can phenotypic plasticity promote or impede adaptive change and diversification? Answering this key question can be experimentally intractable, but closely related clonal species allow a direct approach: experimentally provoking phenotypic plasticity to assess the adaptive significance of both plastic traits and species differences. Two common Caribbean sponge species, Aplysina fulva and A. cauliformis , are nearly indistinguishable molecularly, and share growth form, habitat, and geographical range. This raises questions about species boundaries, within-species variability, and mechanisms of speciation. To distinguish phenotypic plasticity from genetic variation, and learn how plasticity might influence adaptive—and divergent—evolution, I: (i) quantified morphological and ecological characters, (ii) revealed phenotypic plasticity by growing clonemates in different environments, and (iii) related plastic morphological features to ecological function. Characters included skeletal fibre density, biomechanical properties, vulnerability to parasites and predators, wound healing, transport pathways, propagation by fragments, population dynamics, and growth and survival in settings differing in food, sunlight, predators, and water motion. Transplanting both species to a different environment elicited parallel plasticity in the same traits. Combined comparative and experimental data reveal integrated suites of ecologically relevant characters that clearly distinguish these species and allow interpretation of adaptive significance of plastic characters that may underlie divergence. [ABSTRACT FROM AUTHOR]

Monitoring changes in coral reef ecosystems for their conservation and management is important as they are frequently subject to various natural and anthropogenic threats. However, in Sri Lanka, the attention in this regard is to be further concerned for their well‐being. Therefore, this study focused on the selected shallow water (<5 m) coral reefs as Pigeon Island (PIR), Adukkuparu (AR), Salli Beach (SBR), Kayankerni (KR), and Passikuda (PR) on the Eastern coast of Sri Lanka to estimate their changes over 2020, 2021, and 2022. The remote sensing demarcations with the composition of reef ecosystems were done through the analysis of the Allen Coral Atlas data followed by field surveys. Higher accuracy levels for corals were obtained for each site due to field verifying all individual polygons and omitting unmatched polygons of the initial maps from the Allen Coral Atlas. Then, the in‐situ reef surveys were conducted over randomly selected permanent transects at each site. From 2020 to 2022, the live coral percentages have increased in PIR, AR, and SBR while reduced in KR and PR. Dead corals have facilitated the overgrowth of macroalgae. The combined area of live coral on all five reefs has slightly gone up. This increase is primarily due to the rise in live coral cover in AR and SBR. Also, prominent increments of coral diversity have resulted from those sites. Therefore, it is suggested that AR and SBR be designated as Marine Protected Areas to safeguard the newly emerging live corals. [ABSTRACT FROM AUTHOR]

Understanding visitors' willingness to pay (WTP) for natural ecosystems can assist policymakers in managing the environmental assets that form the foundation of nature-based tourism. To earn the highest economic return from limited budgetary resources, tourist-dependent destinations must identify sustainable sources of conservation funding and prioritize spending across ecosystems and initiatives. The purpose of this study is to assess the potential for visitor donations to serve as a source of conservation funding and investigate preferences and willingness to pay for multiple ecosystems concurrently, using data from a stated preference survey administered in Grenada, a small island state in the southern Caribbean that relies on nature-based tourism. Results from a discrete choice experiment and a contingent valuation exercise reveal a reluctance to donate to conservation initiatives by more than half of respondents. Visitors place the highest value on improvements to coral reefs, followed by rainforests, mangroves, and beaches. Average willingness to donate to a conservation trust fund ranged from US $8.00 to US $15.00, and from US $17.00 to US $52.00 for conservation plans targeting improvements to specific ecosystems. Few factors are found to be associated with willingness to pay. Scale heterogeneity may be a more significant source of variation than preference heterogeneity. [ABSTRACT FROM AUTHOR]

Cnidarians are among the most important diploblastic organisms, elucidating many of the early stages of Metazoan evolution. However, Cnidarian fossils from Cambrian deposits have been rarely documented, mainly due to difficulties in identifying early Cnidarian representatives. Halysites, a tabulate coral from Silurian reef systems, serves as a crucial taxon for interpreting Cambrian cnidarians. Traditionally, the biological characteristics of Halysites have been analyzed using methods limited by pretreatment requirements (destructive testing) and the chamber size capacity of relevant analytical instruments. These constraints often lead to irreversible information loss and inadequate data extraction. This means that, to date, there has been no high-resolution three-dimensional mineralization analysis of Halysites. This study aims to introduce novel, non-destructive techniques to analyze the internal structure and chemical composition of Halysites. Furthermore, it seeks to elucidate the relationship between coral organisms and biomineralization in reef settings and to compare Silurian Tabulata with putative Cambrian cnidarians. Techniques such as micro-X-ray fluorescence spectrometry (micro-XRF), micro-X-ray computed tomography (micro-CT), and scanning electron microscopy (SEM) were employed in this research. With the help of high-resolution micro-CT scanning, we identify the growth pattern of Halysites, showing both lateral and vertical development. The lateral multiple-branching growth pattern of Halysites corals is first established herein. The flaggy corallite at the initial stage of branching is also observed. The micro-XRF mapping results reveal the occurrence of septa spines for Halysites, a trait previously thought rare or absent. Additionally, the ratio of coral volume to the surrounding rock was assessed, revealing that Halysites reefs were relatively sparse (volume ratio = ~30%). The cavities between Halysites likely provided more space for other organisms (e.g., rugose corals and bryozoans) when compared to other coral reef types. Additionally, we provide a comparative analysis of post-Cambrian colonial calcareous skeletons, offering insights into the structural features and growth patterns of early skeletal metazoans across the Ediacaran–Cambrian boundary. [ABSTRACT FROM AUTHOR]

Climate‐driven alterations to disturbance regimes are increasingly disrupting patterns of recovery in many biomes. Here, we examine the impact of disturbance and subsequent level of recovery in live hard coral cover on the Great Barrier Reef (GBR) across the last three decades. We demonstrate that a preexisting pattern of infrequent disturbances of limited spatial extent has changed to larger and more frequent disturbances, dominated by marine heatwaves and severe tropical cyclones. We detected an increase in the impact (measured as coral loss) across 265 individual disturbance impacts on 131 reefs in a 36‐year dataset (1985–2022). Additionally, the number of survey reefs impacted by disturbance has increased each decade from 6% in the 1980s to 44% in the 2010s, as has the frequency of mass coral bleaching across the GBR, which has increased between 19% and 28% per year, and cyclones (3%–5% per year), resulting in less time for recovery. Of the 265 disturbance impacts we recorded, complete recovery to the highest levels of coral cover recorded earlier in this study (the "historical benchmark") occurred only 62 (23%) times. Of the 23% of disturbance impacts that resulted in complete recovery to historical benchmarks, 34/62 recovered to their benchmark in 2021 or 2022. Complete recovery was more likely when the historical benchmark was <25% live hard coral cover. The lack of recovery was attributed to recovery time windows becoming shorter due to increases in the frequency of cyclones and of thermal stress events that result in mass coral bleaching episodes. These results confirm that climate change is contributing to ecosystem‐wide changes in the ability of coral reefs to recover. [ABSTRACT FROM AUTHOR]

This article explores the relationship between boring bivalves and their coral hosts in coral reefs. The study conducted field experiments comparing the physiological parameters of Leiosolenus simplex bivalves living in live coral hosts and in corals stripped of their live tissue. Surprisingly, the survival rate and diet composition of the bivalves in both types of hosts were similar, but other indicators of physiological condition, such as pumping rate and oxygen consumption, were lower in bivalves residing in dead coral hosts. The study suggests that while bivalves can survive in dead coral hosts, live coral hosts provide greater food supply and enhance their physiological state. [Extracted from the article]

This article discusses the interactions among three nonindigenous coral species in a tropical marine fouling community. The study focuses on the Tubastraea species, which are invasive corals originally from the tropical Indo-Pacific. The researchers found that these invasive corals can coexist and interact with each other without causing harm. They also observed fusion between colonies of different Tubastraea species, creating chimeric colonies. The study highlights the importance of understanding the interactions between invasive and native species in marine ecosystems. [Extracted from the article]

Biome degradation characterizes the Anthropocene Epoch, and modern ecology is deeply involved with describing the changes underway. Most research has focused on the role of acute disturbances in causing conspicuous changes in ecosystem structure, which leads to an underappreciation of the chronic effects causing large changes through the cumulative effects of small perturbations over decades. Coral reefs epitomize this trend, because the changes in community structure are profound, yet the data to quantify these effects are usually insufficient to evaluate the relative roles of different disturbance types. Here, four decades of surveys from two coral reefs (9 and 14 m depth) off St. John, US Virgin Islands, are used to quantify the associations of acute and chronic events with the changes in benthic community structure. These reefs profoundly changed over 36 years, with coral death altering species assemblages to depress abundances of the ecologically important coral Orbicella spp. and elevating the coverage of macroalgae and crustose coralline algae/turf/bare space (CTB). Linear mixed models revealed the prominent role of chronic variation in temperature in accounting for changes in coverage of corals, macroalgae, and CTB, with rising temperature associated with increases in coral cover on the deep reef, and declines on the shallow reef. Hurricanes were also associated with declines in coral cover on the shallow reef, and increases on the deep reef. Multivariate analyses revealed strong associations between community structure and temperature, but weaker associations with hurricanes, bleaching, and diseases. These results highlight the overwhelming importance of chronically increasing temperature in altering the benthic community structure of Caribbean reefs. [ABSTRACT FROM AUTHOR]

In the 20th century, Australia's Great Barrier Reef emerged as a political battleground when governing bodies planned to turn its coral territories into a vast mining zone. But in the 21st century, as the temporalisation of the Reef exerts increasing influence on the governance, securitisation and anticipation of planetary futures, coral time has emerged as a new site of political and imaginative conflict. Responding to this shift from territory to temporality, how can we pay closer attention to those skilfully making coral time? In this article, I introduce 'dimensional friction' as a tool for considering how the temporal structure of corals intersects with the temporal structure of global climate science in a coring laboratory. Based on my fieldwork at the Australian Institute of Marine Science, I analyse simultaneously discursive, technical, and imaginative problems that emerge when scientists transform the mineral skeletons of corals into time data. Dimensional friction appears whenever this skeletal matter is manipulated, surfacing the lab-based production of vertical time-depth but also suggesting other ways of temporalising (and corporally appropriating) coral time. Viewed in this way, coral cores might be better understood as 'temporal volumes' rather than chronostratigraphic records amenable to linear timelines and trajectories. [ABSTRACT FROM AUTHOR]

Simple Summary: In marine coral reef ecosystems, anemonefish are a group with highly complex behavioral patterns and strict social hierarchies. However, there has been a paucity of research on the factors associated with stable hierarchical relationships or the behaviors performed during competitive interactions, especially in anemonefish in the growth phase before sexual differentiation. In the present study, we employed an observational approach to assess the personality type of each individual by observing the interactive behavior between unsexually differentiated Amphiprion clarkii. Our findings revealed that the personality of A. clarkii varied significantly between individuals, with two main types. Furthermore, our pairing experiments confirmed the impact of personality on the establishment of a stable social hierarchy. These personality-related behavioral traits are potentially important for both individual and population survival, and extend our understanding of the establishment and evolution of social hierarchies in anemonefish and their impact on population dispersal. Furthermore, they have the potential to guide aquaculture practices. In this study, the behavioral ethogram of Amphiprion clarkii during the growth phase prior to sexual differentiation was summarized based on behavioral observations in three social environments. These behaviors can be classified into four categories: in addition to normal behaviors, the other three categories of behaviors—threatening, agonistic, and appeasing behaviors—represent different intentions in interactions with other individuals. Subsequently, the personalities of each individual were assessed by testing their reactions to intruders. These individuals mainly exhibited two distinct personality types: bold-aggressive and shy-submissive. In pairing experiments, the interactive behaviors of the anemonefish were observed in pairing combinations of different body sizes and personalities. The impact of personality on the establishment of a stable social hierarchy was confirmed by significant differences in the success rates of different pairing combinations, with the frequency of appeasing behaviors being the main factor influencing the success rate. Our results suggested that in natural waters, when juvenile individuals migrate among host anemones, shy-submissive individuals are more likely to be accepted due to their appeasing behaviors towards larger individuals, thus avoiding the risk of being attacked and bitten, and benefiting the survival of the individual. Conversely, bold-aggressive individuals are more likely to be driven away to another host anemone due to their unwillingness to settle for a lower-ranked status, thereby contributing to population dispersal and increasing opportunities for gene exchange between populations. [ABSTRACT FROM AUTHOR]

Stony coral tissue loss disease (SCTLD) has devastated coral reefs off the coast of Florida and continues to spread throughout the Caribbean. Although a number of bacterial taxa have consistently been associated with SCTLD, no pathogen has been definitively implicated in the etiology of SCTLD. Previous studies have predominantly focused on the prokaryotic community through 16S rRNA sequencing of healthy and affected tissues. Here, we provide a different analytical approach by applying a bioinformatics pipeline to publicly available metagenomic sequencing samples of SCTLD lesions and healthy tissues from 4 stony coral species. To compensate for the lack of coral reference genomes, we used data from apparently healthy coral samples to approximate a host genome and healthy microbiome reference. These reads were then used as a reference to which we matched and removed reads from diseased lesion tissue samples, and the remaining reads associated only with disease lesions were taxonomically classified at the DNA and protein levels. For DNA classifications, we used a pathogen identification protocol originally designed to identify pathogens in human tissue samples, and for protein classifications, we used a fast protein sequence aligner. To assess the utility of our pipeline, a species-level analysis of a candidate genus, Vibrio , was used to demonstrate the pipeline's effectiveness. Our approach revealed both complementary and unique coral microbiome members compared with a prior metagenome analysis of the same dataset. [ABSTRACT FROM AUTHOR]

The future of marine ecosystems is at risk due to climate change and other human impacts. Specifically, due to ocean warming, some tropical species are expanding their populations while populations of temperate species are in regression, making the establishment of conservation measures imperative to maintain local biodiversity. In this study we establish a baseline on the distribution and abundance of the temperate coral Balanophyllia regia from the Canary Islands. We found that the main environmental factors determining B. regia's distribution and abundance were sea surface temperature and hydrodynamic conditions. Areas under large wave action and colder environments enhanced this warm-temperate species' development. Since its metabolic performance depends exclusively on the surrounding environment, we also propose a methodology to potentially monitor climate change on coastal habitats through this azooxanthellate calcified coral. Results of a tagging experiment showed that a concentration of 20 mg/mL of calcein during 6 h might be enough to in situ label polyps of B. regia without compromising corallite survival. Long-term monitoring of population abundances and growth rates of B. regia through calcein tagging will allow us to identify alterations in local ecosystems early and focus future conservation investments on the most vulnerable areas with higher ecological and economic value. [ABSTRACT FROM AUTHOR]

The northeastern Red Sea (Saudi Arabia) is currently being transformed to become a global hub of economic activity and tourism. This transformation requires the development of pristine coastal areas into populated and dynamic settlements. At the same time, the northern Red Sea is considered a climate refuge for corals in changing climate conditions, and efforts to preserve and protect marine biodiversity are being proposed. Accordingly, foraminifers are an efficient tool to assess and monitor their associated coral reefs' health. This study reports a modern-day health assessment of the corals of Shushah Island (Saudi Arabia) in the northeastern Red Sea as a reference for future monitoring as inferred by applying the FoRAM Index method. In general, our results revealed healthy conditions conducive to coral growth, yet some precautions and regular assessments are recommended. [ABSTRACT FROM AUTHOR]

Climate change stressors are progressively simplifying biogenic habitats in the terrestrial and marine realms, and consequently altering the structure of associated species communities.Here, we used a volcanic CO2 seep in Papua New Guinea to test in situ if altered reef architecture due to ocean acidification reshuffles associated fish assemblages.We observed replacement of branching corals by massive corals at the seep, with simplified coral architectural complexity driving abundance declines between 60% and 86% for an assemblage of damselfishes associated with branching corals. An experimental test of habitat preference for a focal species indicated that acidification does not directly affect habitat selection behaviour, with changes in habitat structural complexity consequently appearing to be the stronger driver of assemblage reshuffling. Habitat health affected anti‐predator behaviour, with P. moluccensis becoming less bold on dead branching corals relative to live branching corals, irrespective of ocean acidification.We conclude that coral reef fish assemblages are likely to be more sensitive to changes in habitat structure induced by increasing pCO2 than any direct effects on behaviour, indicating that changes in coral architecture and live cover may act as important mediators of reef fish community structures in a future ocean. [ABSTRACT FROM AUTHOR]

Coral reef limestone is a biogenic limestone with a hyperdeveloped pore structure. The complex structural features of coral reef limestone can directly affect its mechanical and seepage characteristics, which are not yet well-understood. The pore structure information of two coral reef limestone specimens, including one with coarse pores (CR-C) and one with fine pores (CR-F), was obtained by combining CT scanning technology, 3D visualization reconstruction, and pore identification algorithms. The pore structure characteristics were interpreted considering the porosity's spatial variability, fractal dimension, and tensorial anisotropy. A seepage tensor derived from the geometry component of Hagen-Poiseuille's law was proposed to assess the seepage anisotropy, which was then verified through seepage simulations along different directions. It was found that the spatial distribution of the porosity of CR-C was less uniform than that of CR-F. Both testing specimens had distinct pore structures with obvious directionality that varied with sampling size. Seepage simulations on a representative elementary volume (REV) of CR-C revealed that the permeability along the identified dominant seepage direction was indeed the largest. Some empirical correlations between the permeability and the deviation angle from the dominant seepage direction were established. This study highlights the importance of considering structural anisotropy when interpreting the properties of coral reef limestone. [ABSTRACT FROM AUTHOR]

Marine heatwaves (MHWs), increasing in duration and intensity because of climate change, are now a major threat to marine life and can have lasting effects on the structure and function of ecosystems. However, the responses of marine taxa and ecosystems to MHWs can be highly variable, making predicting and interpreting biological outcomes a challenge. Here, we review how biological responses to MHWs, from individuals to ecosystems, are mediated by fine‐scale spatial variability in the coastal marine environment (hereafter, local gradients). Viewing observed responses through a lens of ecological theory, we present a simple framework of three 'resilience processes' (RPs) by which local gradients can influence the responses of marine taxa to MHWs. Local gradients (1) influence the amount of stress directly experienced by individuals, (2) facilitate local adaptation and acclimatization of individuals and populations, and (3) shape community composition which then influences responses to MHWs. We then synthesize known examples of fine‐scale gradients that have affected responses of benthic foundation species to MHWs, including kelp forests, coral reefs, and seagrass meadows and link these varying responses to the RPs. We present a series of case studies from various marine ecosystems to illustrate the differential impacts of MHWs mediated by gradients in both temperature and other co‐occurring drivers. In many cases, these gradients had large effect sizes with several examples of local gradients causing a 10‐fold difference in impacts or more (e.g., survival, coverage). This review highlights the need for high‐resolution environmental data to accurately predict and manage the consequences of MHWs in the context of ongoing climate change. While current tools may capture some of these gradients already, we advocate for enhanced monitoring and finer scale integration of local environmental heterogeneity into climate models. This will be essential for developing effective conservation strategies and mitigating future marine biodiversity loss. [ABSTRACT FROM AUTHOR]

Island species-area relationship (ISAR) is the most documented pattern in island biogeography. Different hypotheses were advanced to explain this pattern. In this study, I selected 27 remote Tuamotu atolls in the South Pacific Ocean with complete surveys of native species richness of birds and vascular plants to test the influence of four abiotic predictors on species richness (atoll emerged area, habitat diversity, mean elevation, and number of islets). Linear regressions were used to assess the relative influence of predictors on native species richness while stepwise regression was then used to identify the best model. Atoll area was a significant predictor to explain native bird and plant species richness, attesting ISAR on the remote surveyed atolls. Stepwise model demonstrated that both habitat diversity and atoll area explained bird species richness, whereas atoll area and mean elevation were the best predictors for native plants. These results suggest that ISAR can be related to different hypotheses, depending on the taxon studied. Among hypotheses, the simple "target-area" hypothesis was a suitable framework to explain ISAR of native birds, while the "disturbance" hypothesis was relevant to support ISAR of native plants observed on the atolls. [ABSTRACT FROM AUTHOR]

Healthy coral reefs provide diverse habitats for marine life, playing a crucial role in marine ecosystems. Coral health is under threat due to global climate change, ocean pollution, and other environmental stressors, leading to coral bleaching. Coral bleaching disrupts the symbiotic relationship between corals and algae, ultimately impacting the entire marine ecosystem. Processing complex underwater images manually is time-consuming and burdensome for marine experts. To rapidly locate and monitor coral health, deep neural networks are employed for identifying coral categories, which can facilitate the automated processing of extensive underwater imaging data. However, these classification networks may overlook critical classification criteria like color and texture. This paper proposes a multi-local perception network (ML-Net) for image classification of healthy and bleached corals. ML-Net focuses on local features of coral targets, leveraging valuable information for image classification. Specifically, the proposed multi-branch local adaptive block extracts image details through parallel convolution kernels. Then, the proposed multi-scale local fusion block integrates features of different scales vertically, enhancing the detailed information within the deep network. Residual structures in the shallow network transmit local information with more texture and color to the deep network. Both horizontal and vertical multi-scale fusion blocks in deep networks are used to capture and retain local details. We evaluated ML-Net using six evaluation metrics on the Bleached and Unbleached Corals Classification dataset. In particular, ML-Net achieves an ACC result of 86.35, which is 4.36 higher than ResNet and 8.5 higher than ConvNext. Experimental results demonstrate the effectiveness of the proposed modules for coral classification in underwater environments. [ABSTRACT FROM AUTHOR]

Coral reefs worldwide are under increasing levels of pressure due to global and local stressors. Long-term monitoring of coral reefs through repeated observations at fixed survey sites allows scientists to assess temporal patterns in coral-reef communities and plays important roles in informing managers of the state of the ecosystems. Here, we describe coral assemblages in Papahānaumokuākea, the largest contiguous fully protected marine conservation area in the United States, using long-term monitoring data collected from 20 permanent (fixed) sites at three islands/atolls, Lalo, Kapou and Manawai, between 2014 and 2021. Significant temporal shifts in coral colony composition were detected at some of the monitoring sites, which were attributed to the impact of a mass coral bleaching event in 2014 and Hurricane Walaka in 2018. In particular, the bleaching affected multiple sites at Kapou and one site at Manawai where coral assemblages shifted from the Montipora dilatata/flabellata/turgescens complex to M. capitata dominance; despite being the dominant species at multiple monitoring sites prior to the bleaching, the M. dilatata/flabellata/turgescens complex has not been recorded at any of our monitoring sites in recent years. Coral conditions, such as bleaching, predation, subacute tissue loss, Porites pigmentation response and trematodiasis, did not show differences in the occurrence among the three islands/atolls once the site and temporal variabilities, as well as environmental covariates for bleaching, were considered. Coral genera, however, exhibited different sensitivities to these conditions. These findings highlight the importance of continuing coral reef monitoring at the species level, covering a broad range of coral assemblage compositions and habitat types in Papahānaumokuākea. [ABSTRACT FROM AUTHOR]

Coral reefs in the Florida Reef Tract have seen protracted loss of coral over the past several decades due to a variety of disturbances from marine heat waves, cold snaps, and disease events. Corals have not recovered despite abundant herbivorous fishes and relatively low macroalgal cover, two factors thought to facilitate resilience of corals. Thus, factors affecting the replenishment of coral populations may be hindering the recovery of corals. To study the potential factors affecting coral recovery in reefs of the Florida Reef Tract, we assessed benthic abiotic variables (substrate slope, depth, structural complexity, and abundance of sediment), fish assemblages, and benthic composition in three different reef habitats (groove, spur wall, spur top) located on three low-relief reefs and three high-relief spur-and-groove reefs. Herbivorous fish biomass ranged (44.7–107 g m−2), which is above average for the Caribbean. Yet there was low coral cover (~ 1%) and low density (~ 1 coral m2) of small adult corals, which likely reflects the cumulative effects of years of disturbances. The presence and density of juvenile corals were negatively correlated with the depth of the sediment layer trapped within long, sediment-laden algal turfs (LSAT), which are particularly abundant (> 50% cover) in low complexity reef habitats (low-relief groove, low-relief spur top, and high-relief groove). Our results indicate that current unsuitable habitat conditions (high sediment load) for early life stage corals may be an important factor preventing coral recovery. Consequently, the abundance of herbivorous fishes and coral cover trajectories appear decoupled in the region, and additional management initiatives considering LSAT composition are required to aid reef resilience. [ABSTRACT FROM AUTHOR]

Coral–algal interactions are pivotal in reef ecosystems globally as they can scale up ecosystem levels and lead to dominance shifts. In this study, we conducted a systematic review of global coral–algal interactions, identifying the most studied locations, species, and types of interactions. We then assessed how these interactions may be impacted by consumers and climate change. Over the past 20 years (2001–2020), coral and algae interactions were mostly explored in the Pacific, and the Caribbean and US East Coast, where branching and massive corals were the focus, while other coral growth forms received less attention, and effects on algae were often overlooked. Adult corals were generally reported to be damaged when directly interacting with algae through physical abrasion or allelopathy. Conversely, algae interactions were found to have a positive impact on juvenile corals by facilitating larval recruitment and settlement. As expected, coral–algal interactions and the type of coral–algal relationships vary globally, most likely due to differences in abiotic conditions, community composition and the number of studies performed in a region. Despite the large emphasis on the role of consumers in controlling coral–algal interactions, few studies directly explored the effects of herbivory on coral–algal interactions. Given the growing evidence that ocean warming and acidification can reduce the competitive ability of corals, understanding the dynamic relationships between coral, algae, and consumers under future climate change conditions is crucial in predicting future coral recruitment potential and reef composition patterns. Here, we highlight the main findings from coral–algal interaction studies performed in the last 20 year and point to future directions, such as: 1) diversifying location, coral species, growth forms and life phases; 2) considering effects on both sides of interaction, not neglecting effects on algae; and 3) taking a closer look into the role of consumers and microbiomes. Advancing our understanding of coral–algal interactions, as well as how these interactions shift under changing conditions, is critical in predicting how coral reef ecosystems may operate in the future. [ABSTRACT FROM AUTHOR]

Tropical coral reefs are a critical ecosystem in global peril as a result of anthropogenic climate change, and effective conservation efforts require reliable methods for identifying and predicting coral bleaching events. To this end, temperature threshold-based models such as the National Oceanic and Atmospheric Administration's (NOAA) degree-heating week (DHW) metric are useful for forecasting coral bleaching as a function of heat stress accumulation. DHW does not adequately account for regional variation in coral stress responses, however, and the current definition consistently underpredicts coral bleaching occurrence. Using a weather forecasting skill-based framework, our analysis cross-tested 1080 variations of the DHW-based bleaching occurrence (presence/absence) model against 22 years of contemporary coral bleaching observations (1998–2019) in order to optimize bleaching forecast skill at different levels of geographic specificity. On a global basis and relative to the current definition, reducing the current 1 °C warming cutoff to 0.4 °C, adjusting the accumulation window to 11 weeks, and defining a bleaching threshold of 3 DHW improved forecast skill by 70%. Allowing our new DHW definitions to vary across regions and ocean basins further doubled model skill. Our results also suggest that the most effective bleaching forecast models change over time as coral reef systems respond to a shifting climate. Since 1998, the coral bleaching threshold for the globally optimized forecast model has risen at a significant rate of 0.19 DHW/year, matching the pace of ocean warming. The bleaching threshold trajectory for each ocean basin varies. Though further work is necessary to parse the mechanism behind this trend, the dynamic nature of coral stress responses demands that our forecasting tools be continuously refined if they are to adequately inform marine conservation efforts. [ABSTRACT FROM AUTHOR]

Ocean acidification (OA) and ocean warming (OW) affect the calcification of corals, and intraspecific variations in response to these stressors in the population level need to be clarified for better future predictions. Using Acropora digitifera as our subject, we examined the intraspecific variability in calcification and maximum quantum yield (Fv/Fm) of photosystem II of symbiotic zooxanthella in responses to OA, OW, and OA + OW. Samples were taken from two different sites: Sesoko Station (warmer) and Sesoko South (cooler) in Okinawa, Japan. Calcification rates varied between the two sites, and noticeable differences were observed only among coral colonies from the Sesoko South site, specifically under control and OA treatments. Furthermore, Fv/Fm showed no variation between the sites due to those stresses. Hence, the calcification rates among A. digitifera colonies varied by habitat, and we found within-site variation only in the lower temperature location, Sesoko South. We observed diminished variation in response among colonies in the warmer site. The adapting to diverse environmental conditions and responding to changes such as seawater pCO2 and temperature, may lead to differences in sensitivity between the two populations to OA, OW, and OA + OW. These intraspecific variation could arise from factors like acclimatizations, the influence of specific genotypes, or phenotypic plasticity of the colonies. [ABSTRACT FROM AUTHOR]

Coral reef ecosystems host diversified and highly productive communities, but corals are degrading in many places worldwide. Picking suitable locations to maximize coral conservation and restoration efforts is critical. From a mass balance point of view, the supply of new nutrients is crucial to support a productive and reef-building coral ecosystem. Quantifying and qualifying available nutrients provide information to set region-specific thresholds for anthropogenic pollution monitoring and to generate research hypotheses. Here, we report the inorganic and organic nutrient levels from twenty-three sampling sites in coral reefs and coastal waters covering regions from high to low coral coverage, including two remote islands, Dongsha Atoll and Taiping Island, in the South China Sea. Some of the surveyed reefs received external inorganic nutrient supply via upwelling or submarine groundwater discharge (SGD), suggesting sites potential for new production (i.e., reef-building). Production or removal of organic matter at various sites is evidenced by their elevated or depleted organic carbon and nitrogen concentrations, respectively. The degree of impact by the upwelling and SGD on various inorganic and organic nutrient distribution varies. Among all sites, organic nitrogen accounts for most of the total nitrogen and is potentially a significant nitrogen source for the environment. The highly correlated total organic nitrogen (TON) concentrations and their C-to-N ratios (C/N-TON) suggest the production of TON with low C/N-TON and preferential removal of N during remineralization processes, leaving "leftover" TON with high C/N ratios. Furthermore, we found that high coral diversity and coverage sites are featured in low organic matter with high C/N, while macroalgae-dominating sites had elevated organic matter. The new data are valuable to generate hypotheses for future research to test, for example, whether sites with low organic matter are more suitable for restoring reef-building corals than sites with high organic matter. [ABSTRACT FROM AUTHOR]

The tropical southwest Indian Ocean is a coral biodiversity hotspot, with remote reefs physically connected by larval dispersal through eddies and a complex set of equatorial and boundary currents. Based on multidecadal, 2 km resolution hydrodynamic and larval dispersal models that incorporate temporal variability in dispersal, we find that powerful zonal currents, current bifurcations, and geographic isolation act as leaky dispersal barriers, partitioning the southwest Indian Ocean into clusters of reefs that tend to consistently retain larvae, and therefore gene flow, over many generations. Whilst exceptionally remote, the Chagos Archipelago can broadcast (and receive) considerable numbers of larvae to (and from) reefs across the wider southwest Indian Ocean, most significantly exchanging larvae with the Inner Islands of Seychelles, but also the Mozambique Channel region. Considering multi-generational dispersal indicates that most coral populations in the southwest Indian Ocean are physically connected within a few hundred steps of dispersal. These results suggest that regional biogeography and population structure can be largely attributed to geologically recent patterns of larval dispersal, although some notable discrepancies indicate that palaeogeography and environmental suitability also play an important role. The model output and connectivity matrices are available in full and will provide useful physical context to regional biogeography and connectivity studies, as well as supporting marine spatial planning efforts. [ABSTRACT FROM AUTHOR]

Global coral reef degradation has precipitated phase shifts toward macroalgal-dominated communities. Despite the negative repercussions for reefscapes, higher abundances of primary producers have the potential to positively impact the physicochemical environment and mitigate negative impacts of ocean acidification (OA). In this study, we investigated the influence of macroalgal (cf. Sargassum vulgare) density on coral (Acropora millepora and A. hemprichii) calcification rates under current and future OA conditions. Corals were resistant to OA up to ~ 1100 µatm, with no changes in calcification rates. However, the presence of (low and high density) algae reduced calcification rates by ~ 41.8%, suggesting either a chemical defense response due to algal metabolites or potential physical impacts from shading or abrasion. Documented beneficial buffering effects of macroalgae in OA may also elicit negative impacts on coral calcification, suggesting further work is needed to elucidate how species interactions influence responses to projected climate change. [ABSTRACT FROM AUTHOR]

Understanding the drivers of food web community structure is a fundamental goal in ecology. While studies indicate that many coral reef predators depend on pelagic subsidies, the mechanism through which this occurs remains elusive. As many of these species are important fishery targets, a better understanding of their trophodynamics is needed. To address these gaps, we employed a comprehensive structural equation modelling approach using extensive surveys of the reef community to explore relationships between groupers and snappers, their prey, and the surrounding habitat in an oceanic coral reef system. There were significant positive relationships between site-attached and transient planktivores and grouper and snapper biomass, respectively, indicating that pelagic subsidies are transferred to upper trophic levels through planktivores. Contrary to previous studies, habitat complexity and depth were not important for predators or prey. Instead, corallivores and site-attached and transient planktivores were primarily associated with live habitat and coral cover. This indicates that a decline in coral cover could have severe direct and indirect impacts on the structure and functioning of multiple levels of the reef food web. While pelagic reliance may suggest that predators are resilient to bleaching-related habitat loss, the associations of their planktivorous prey with live coral suggest that both benthic and pelagic pathways should be preserved for continued resilience of these food webs and their fisheries. By considering direct and indirect relationships, our study generated insights not only on the complex dynamics of coral reef ecosystems, but also on how they may respond to environmental change. [ABSTRACT FROM AUTHOR]

The Fourth Global Coral Bleaching Event, confirmed by the National Oceanic and Atmospheric Administration (NOAA) and the International Coral Reef Initiative (ICRI), is a significant environmental challenge caused by climate change. The event began in the Caribbean in 2023 and has since spread to the Southern Hemisphere. The severity of the bleaching is driven by climate change, with El Niño events exacerbating the situation. The event has already caused devastating damage to coral reefs worldwide. To address this crisis, the International Coral Reef Society (ICRS) emphasizes the need for action in three key areas: mitigating greenhouse gas emissions, mitigating local stressors, and conducting active restoration efforts. Coral reef scientists play a crucial role in collecting standardized data, collaborating internationally, and protecting local reefs. Additionally, direct interventions such as coral restoration can provide hope for the future of coral reefs. However, urgent global efforts and funding are necessary to prevent further damage and ensure the survival of these ecosystems. [Extracted from the article]

Global warming can inhibit chlorophyll-based solar energy capturing of phytoplankton by decreasing nutrient supply through upwelling. However, species with proton-pump rhodopsin (PPR) can independently convert solar energy to cope with nutrient limitation. Besides prokaryotes, PPR has been documented in dinoflagellates and some species of other algal lineages, and its potential role in compensating for the deficiency of phosphorus has been demonstrated in dinoflagellates. However, PPR has not been studied in the coral reef endosymbiotic Symbiodiniaceae. Here, we report a PPR in Breviolum minutum (BmR). Both phylogenetic analysis and structure prediction results indicate that BmR resembles eukaryotic proton-pump rhodopsins, phylogenetically affiliated with the subgroup xanthorhodopsins. BmR contains the critical residues for proton pumping, retinal binding, and spectrum tuning for green absorption. To explore BmR's potential roles in responding to phosphorus limitation, we cultured B. minutum under different phosphorus conditions, and monitored physiological and BmR's transcriptional responses. Phosphorus limitation caused decreases in B. minutum population growth and photosynthesis efficiency. Meanwhile, our quantitative PCR showed that BmR expression was strongly upregulated under phosphorus limitation, showing a strong positive correlation with alkaline phosphatase activity and a negative correlation with photosynthetic efficiency. Our findings demonstrate that proton-pump rhodopsin occurs in Symbiodiniaceae and BmR has the potential to provide supplementary energy to support cell basal metabolisms when photosynthesis of B. minutum is impaired by phosphorus limitation, thereby enabling corals to better weather climate change. [ABSTRACT FROM AUTHOR]

Crown-of-thorns seastar (CoTS, Acanthaster cf. solaris) outbreaks remain a significant cause of coral loss on the Great Barrier Reef (GBR) and across the West-Pacific Ocean. Previous outbreaks on the GBR have only been discovered once fully established, which constrains opportunities for effective control. Early detection of outbreaks would provide an important opportunity for early intervention and increase understanding of outbreak cause(s). Here, we assess the utility of environmental DNA (eDNA) monitoring to detect the initiation of a population outbreak at Lizard Island over five years (2019–2023), compared with density estimates obtained using Scooter-Assisted Large Area Diver-based (SALAD) surveys. At each of the five eDNA sampling sites, 30 replicate samples were collected annually and analysed with CoTS-specific primer sets and digital droplet PCR. Both methods detected distinct increases in CoTS densities from 2020/21 onwards, indicating the start of a new population outbreak. A large part of the observed variation in eDNA (expressed as the percentage of positive samples) was explained by changes in recorded CoTS density, confirming that eDNA data provide a quantitative estimate for adult CoTS abundance. SALAD surveys and eDNA are new and complementary monitoring methods that facilitate early detection of CoTS outbreaks, which will enable more effective management intervention. [ABSTRACT FROM AUTHOR]

Algal ridges are protective features for coral reefs that form through the accretion and encrustation of reef rubble and debris by crustose coralline algae (CCA) and processes of diagenetic cementation. Carbonate precipitation and dissolution dynamics on and within algal ridge frameworks are poorly understood. We studied the surface and subsurface geochemistry of the algal ridge framework at One Tree Island, Australia. Measurable quantities of hydrogen sulphide were detected in most porewater samples collected from bores, indicating a largely anoxic ridge framework. Total alkalinity (TA) and pH measurements indicate that the precipitation of carbonate minerals within the interior of the ridge framework occurs under largely anoxic conditions and is likely to be driven by TA changes associated with sulphate-reducing bacteria. Modelling of porewater hydrogen sulphide concentrations in combination with TA and dissolved inorganic carbon (DIC) indicates anoxic respiration processes produce alkalinity within the algal ridge framework. However, significantly more TA is removed via the precipitation of mineral carbonate, resulting in porewater TA concentrations falling below the open seawater values. The precipitation of mineral carbonate also lowers interstitial water pH, such that pH changes are not solely from organic carbon diagenesis. The simultaneous precipitation and dissolution of carbonate minerals within the algal ridge framework are key to forming and cementing algal ridges, which are important physical protective features for coral reefs. [ABSTRACT FROM AUTHOR]

Exposure to more frequent ocean warming events is driving the loss of coral reef cover as the window of recovery between episodes of bleaching reduces. Coral propagation via in situ nurseries and subsequent outplanting have increased worldwide to support replenishing coral cover on degraded reefs. However, challenges in identifying fast-growing and bleaching-resistant target corals have limited how informative we can be regarding the resilience of outplanted corals. Here, we employed short-term thermal stress assays using the Coral Bleaching Automated Stress System (CBASS) to assess the thermal threshold of a fast-growing coral pre- and post-propagation on in situ nursery frames. We show that year-long nursery-propagated corals exhibit a statistically significant reduction in thermal thresholds (i.e., ED50s) compared to their corresponding reef-based donor colonies based on dose–response modelling of dark acclimated photosynthetic efficiency. RNA-Seq was then used to assess the underlying drivers of this thermotolerance reduction, identifying that processes involved in metabolic and oxidative stress management were disrupted in nursery versus donor heat-treated corals. Whether trade-offs during potential growth-focused phases (post-fragmentation), nursery conditions, and/or a consecutively high summer heat-load drove the lower thermal capacity remains to be determined. However, nursery corals expressed genes associated with telomere maintenance, which are typically expressed in stress-sensitive fast-growing corals under seasonal environmental stress, suggesting consecutively high summer heat-loading contributed to the observed patterns. Our results highlight that thermal tolerance is (i) variable and (ii) subject to acclimation to varying degrees across colonies. Thus, a path forward for reef practitioners to improve propagation efforts may entail the initial screening of a larger reef population from which thermally superior colonies can be selected for propagation. [ABSTRACT FROM AUTHOR]

One of the least understood trophic pathways on coral reefs is the linkage between highly productive cryptic motile invertebrates (herein: cryptofauna) and the predatory vertebrates that underpin reef fisheries. As cryptofauna are difficult to observe and quantify, particularly in coral rubble where they proliferate, the diets of invertivores that forage in rubble have largely been determined through relative gut content analyses. Without congruent quantification of prey diversity, biomass, and rates of predation specific to rubble, it remains challenging to develop models of productivity and energy transfer. We calculated bite rates of six wrasses (Labridae) and a goatfish (Mullidae) commonly found foraging in rubble, using in situ videography on a coral reef in Palau, Western Micronesia. Consumption rates (i.e. individuals consumed) and prey preferences were determined using tank-based feeding experiments, where individual fish were presented with a diverse rubble community characterised before and after 2 h feeding trials. The motile cryptofauna community and invertivore diet consisted predominantly of Arthropoda (83% and > 58%, respectively), with calanoid copepods and mysids positively selected and harpacticoids, decapods and ostracods negatively selected. The interspecific mean (± standard error) rate of consumption was 3.5 ± 0.2 ind. min−1 from rubble, estimated to equal 9.5 ± 0.9 mg min−1 of invertebrate biomass consumed per fish, with biased uptake of small fauna. Bite and consumption rates varied among species with the greatest efficiency in biomass uptake evident in Halichoeres melanurus. This study provides a first attempt at characterising diverse cryptofauna communities pre- and post-trial to identify feeding rates and preferences of coral reef invertivores from the rubble benthos, and highlights the importance of addressing the bioavailability of lower trophic entities in energy pathways. [ABSTRACT FROM AUTHOR]

Rainfall and sea tides significantly affect the coastal groundwater. The effect of rainfall events and sea tides on groundwater is not fully understood. In this study, groundwater level and electrical conductivity (EC) were simultaneously measured in three monitoring wells to evaluate the behaviour of freshwater in the uplifted atoll island of Zhaoshu, China. We used the water level sensor monitoring the position and variability of freshwater in the island. In the monitoring period, 86 rainfall events (cumulative rainfall above 1 mm) were identified. The fresh groundwater periodically fluctuates with phase lags every 1–2 h following sea tides. The intermittent rainfall increases the volume of fresh groundwater, while groundwater fluctuation is controlled by tides. Multiple regression analysis and cross‐correlation analysis were used to analyse the response relationship of groundwater to rainfall and tides. Variation in the groundwater level lags the EC as the temporal fluctuation of the sea tides. Only in case of severe rainstorm (cumulative precipitation of an event above 300 mm), the contribution of rainfall on groundwater level fluctuation is greater than that of sea tide. Four response modes (RRR, RFF, RFR, RRF) decomposition of groundwater have been defined according to the tidal stage and threshold (70.3–301.1 mm) of rainfall. The tidal‐induced groundwater effect (TGE) is stronger than the rainfall‐induced groundwater effect (RGE) but it is the opposite in the third and fourth modes. These results and mechanisms could be applied to other atoll islands, for our understanding of rainfall infiltration processes with tidal effect, and could be instrumental in estimating groundwater resources. [ABSTRACT FROM AUTHOR]

Reconstruction of ancient sea level during the Late Pleistocene Marine Isotope Stage 5e (MIS 5e), from ∼129 to 116 ka, has the potential to improve the accuracy of future global sea level projections by providing a key benchmark for model calibration during a past warm period. Shallow‐water carbonate exposures comprising the tectonically stable Bahamas and Turks and Caicos Islands contain a regional unconformity that suggests MIS 5e sea level variability. It is not yet fully understood whether this intra‐MIS 5e unconformity was formed under subaerial or submarine conditions. The current study applies next generation sedimentologic, stratigraphic and petrographic analyses across the intra‐MIS 5e erosional unconformity exposed at four locations on West Caicos to reconstruct the conditions in which it formed. The unconformity is characterized with field mapping and digital terrain models, combined with U‐Th coral dating from previous studies. Marine and meteoric diagenetic alteration events were determined by integrating field observations and high‐resolution brightfield and autofluorescence microscopy to compile a comprehensive paragenetic sequence of the intra‐MIS 5e unconformity. Results indicate the erosional unconformity coincided with a rapid 1–3 m sea level fall resulting in beveled in situ coral heads and spatially constrained meteoric diagenesis. Current models of solar insolation and global‐scale ice sheet dynamics currently do not predict an intra‐MIS 5e sea level fall or associated climatic fluctuations. Illuminating the magnitude and timing of an intra‐MIS 5e sea level fall will provide better constraints on numerical models that link ice sheet collapse and climate change. Key Points: High‐resolution microscopy is applied to Marine Isotope Stage 5e (MIS 5e) coral reef, beach and dune deposits on West Caicos to reconstruct sea level historyA 1–3 m sea level fall formed an intra‐MIS 5e erosional surface between lower (127.1 ± 1.1 ka) and upper 5e (121.0 ± 1.0 ka) depositionIsland stratigraphy preserves a record of millennial sea level and climate variability not reflected in current LIG numerical models [ABSTRACT FROM AUTHOR]

Coral reef ecosystems are facing severe degradation due to anthropogenic activities at both local and global scales. In response, extensive restoration efforts are underway, aiming to bolster coral cover and enhance reef fish communities to foster facilitation between fish and corals. This reciprocal relationship is anticipated to improve overall restoration efficacy and enhance coral reef resilience in the face of global warming. Here, we investigate the impact of coral restoration using out-planted Acropora cervicornis colonies attached to raised domes on the associated fish community on the isolated, well-protected reef of Little Cayman Island in the Central Caribbean. Surveys were conducted immediately preceding out-planting, five days later, and 85 days later to capture temporal changes in the fish community. After 85 days of out-planting, there were no changes in fish biomass, abundance, or species richness for the entire fish community. This pattern was consistent for selected fish functional groups. Additionally, no significant differences were observed in the fish community before outplanting, five days after out-planting, or 85 days after out-planting of restoration domes. Our results underscore the limited impact of coral restoration for influencing fish communities in the isolated and highly protected reef of Little Cayman over an 85-day period. Consequently, our findings have implications for using coral restoration as a mechanism to enhance fish populations, particularly in marginally disturbed regions where structural complexity has not been lost. Future restoration programs should therefore incorporate local knowledge of environmental history and restoration needs along with an increased data-driven understanding of the intricate interaction between fish and coral populations to be successful. [ABSTRACT FROM AUTHOR]

Mesophotic Coral Ecosystems (MCEs) represent unique ecological habitats that range from 30 to 150 m deep, harbouring phylogenetically distinct species and offering refuge for many taxa during times of environmental stress. Yet owing to inaccessibility of ecosystems at these depths, most MCEs remain unexplored, with quantifications of ecological communities in these habitats lacking across many regions. Here, using open- and closed-circuit technical diving, we quantified benthic and fish community composition at four mesophotic reef sites (45 m depth) in Grand Cayman. We show significant differences in benthic community composition over a small spatial scale driven by disparate coverage of sponges, crustose coralline algae, and sand/rubble, yet consistent patterns of macroalgal dominance representing >50% coverage at each site and low hard coral cover at an average of 2.4%. Reef fish species richness, biomass, and density was consistent across sites, however the relative contribution of individual species to community composition differed significantly. Macrocarnivores were found to be the dominant contributors to biomass, with invertivores the most speciose, and omnivores and planktivores at the highest densities, consistent with previous descriptions of mesophotic fish assemblages in other regions. Similarly, the low hard coral cover and high macroalgae and sponge cover of the benthic communities also appear ecologically similar to several described mesophotic reefs yet is not uniform across the Caribbean. The ecological organisation of Grand Cayman's MCEs may result from a variety of factors such as isolation from other major land masses, geology, local geography, and anthropogenic activity at both the local and global scale and highlight the importance of continued exploration and documentation of MCE communities. [ABSTRACT FROM AUTHOR]

Coral reefs protect coastlines from inundation and flooding and serve over 200 million people globally. Wave transformation has previously been studied on coral reef flats with limited focus on forereef zones where wave transformation is greatest during high‐energy conditions. This study investigates the role of forereef spur and groove (SaG) morphology in wave energy dissipation and transmission at the reef crest. Using XBeach on LiDAR‐derived bathymetry from One Tree Island in the southern Great Barrier Reef, we reproduced dissipation rates comparable to SaG field studies. We examined how wave energy dissipation differs between realistic bathymetry and those with SaG features removed, demonstrating an up to 40% decrease in dissipation when SaG features are absent. We then investigated changes to wave energy dissipation and wave transmission at the reef crest based on IPCC AR5 emission scenarios (RCP2.6 and RCP8.5) and a total disaster scenario (TD) for the year 2100. For RCP2.6, an increase in wave heights of 0.8 m and an increase in water level of 0.3 m resulted in a two‐fold increase in dissipation rates. For RCP8.5 and TD, with no increase in incident wave height, dissipation rates were 29% and 395% lower than RCP2.6. This resulted in increased wave transmission at the reef crest by 1.8 and 2.7 m for the RCP8.5‐ and TD based models, respectively, when compared to the RCP2.6‐based model. The results from our novel modeling approach of using long‐shore varying accurate bathymetry on forereefs show increased wave energy dissipation rates with implications for reducing coastal flooding and island inundation on reef‐lined coasts. Plain Language Summary: Coral reefs protect coastlines from floods and waves, benefiting over 200 million people globally. We studied how waves change over coral reefs, focusing on the forereef zone where wave transformation is most significant during high‐energy conditions. The shape of the forereef, specifically the long comb‐like grooves that cut through coral reefs, known as spur and grooves (SaG), modify wave energy transformation. Utilizing digital representation of waves over accurate reef shapes (known at bathymetry), we simulated wave dissipation rates comparable to real‐world SaG studies. By comparing high resolution, accurate bathymetry to smoothed bathymetry with SaG removed, we demonstrate a 40% decrease in wave energy dissipation. Next, we investigated how wave energy dissipation changes in different forereef environments. We considered low and high emission scenarios (RCP2.6 and RCP8.5) from the IPCC AR5 report and a total disaster scenario (TD) for the year 2100, considering changes to wave power, and water‐level. We found that models based on high‐emission scenarios (RCP 8.5) had decreased dissipation rates, resulting in more water passing the reef crest. Our study highlights the benefits of using accurate reef shapes in simulating wave energy dissipation on coral reefs. Accurate bathymetry can incorporate features such as SaG of different shapes, which increase wave dissipation. Key Points: Accurate bathymetry (<1 m) in forereef wave energy dissipation models can include features such as spurs and grooves (SaG)SaG increases forereef wave energy dissipation when compared to similar bathymetry without SaGForereef dissipation shifts from bed friction to wave breaking in modeled environmental conditions based on future climate projections [ABSTRACT FROM AUTHOR]

Tropical reefs encompass tremendous biodiversity yet are imperiled by increasing natural and anthropogenic disturbances worldwide. Meiobenthic biota on coral reefs, for example, ostracods, may experience substantial diversity loss and compositional changes even before being examined. In this study, we investigated the reefal ostracod assemblages from the highly diverse and productive ecosystem in the Zanzibar Archipelago (Pemba, Zanzibar, and Mafia islands), Tanzania, to understand how their diversity and faunal structure vary in response to water depth, benthic community type, and human impacts. We characterized four distinct ostracod faunas associated with different benthic habitats, which were deep fore reefs, shallow fringing reefs, degraded fringing reefs, and algae-covered intertidal flats. We identified typical ostracod associations, i.e., Bairdiidae versus Loxoconchidae–Xestoleberididae, that showed affinities towards hard corals or algae on the reef platforms, respectively. The highest diversity was found on shallow fringing reefs where coral-affined and algae-affined taxa exhibited maximum overlap of their distributional ranges, while the sand flats, mangrove, and marginal reefs within the intertidal zone had much lower diversity with a high dominance of euryhaline taxa. Along the western coast of Zanzibar Island, coastal development likely resulted in a unique faunal composition and comparatively low diversity of ostracod assemblages among those in reefal habitats, in conjunction with overall reef ecosystem degradation. This study represents the first large-scale assessment of shallow-marine ostracods in the Zanzibar Archipelago. It lays a solid foundation for future research into the ecological significance of ostracods on coral reefs. [ABSTRACT FROM AUTHOR]

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

Background: Marine benthic prokaryotic communities play crucial roles in material recycling within coastal environments, including coral reefs. Coastal sedimentary microbiomes are particularly important as potential reservoirs of symbiotic, beneficial, and pathogenic bacteria in coral reef environments, and therefore presumably play a core role in local ecosystem functioning. However, there is a lack of studies comparing different environments with multiple sites on the island scale, particularly studies focusing on prokaryotic communities, as previous investigations have focused mainly on a single site or on specific environmental conditions. In our study, we collected coastal sediments from seven sites around Okinawa Island, Japan, including three different benthic types; sandy bottoms, seagrass meadows, and hard substratum with living scleractinian corals. We then used metabarcoding to identify prokaryotic compositions and estimate enzymes encoded by genes to infer their functions. Results: The results showed that the three substrata had significantly different prokaryotic compositions. Seagrass meadow sites exhibited significantly higher prokaryotic alpha-diversity compared to sandy bottom sites. ANCOM analysis revealed that multiple bacterial orders were differentially abundant within each substratum. At coral reef sites, putative disease- and thermal stress-related opportunistic bacteria such as Rhodobacterales, Verrucomicrobiales, and Cytophagales were comparatively abundant, while seagrass meadow sites abundantly harbored Desulfobacterales, Steroidobacterales and Chromatiales, which are common bacterial orders in seagrass meadows. According to our gene-coded enzyme analyses the numbers of differentially abundant enzymes were highest in coral reef sites. Notably, superoxide dismutase, an important enzyme for anti-oxidative stress in coral tissue, was abundant at coral sites. Our results provide a list of prokaryotes to look into in each substrate, and further emphasize the importance of considering the microbiome, especially when focusing on environmental conservation. Conclusion: Our findings prove that prokaryotic metabarcoding is capable of capturing compositional differences and the diversity of microbial communities in three different environments. Furthermore, several taxa were suggested to be differentially more abundant in specific environments, and gene-coded enzymic compositions also showed possible differences in ecological functions. Further study, in combination with field observations and temporal sampling, is key to achieving a better understanding of the interactions between the local microbiome and the surrounding benthic community. [ABSTRACT FROM AUTHOR]

This corrigendum addresses an error in the default seawater dimethylsulfide (DMS) climatology used in a study on the influence of coral-reef-derived DMS on the atmosphere of the Great Barrier Reef. The correction states that the correct climatology should be Kettle et al. (1999) instead of Lana et al. (2011). However, this correction does not impact the study's results, and no new seawater DMS measurements for the Great Barrier Reef region have been included in newer climatologies. The document also references three scientific articles that may be relevant to library patrons researching climate and oceanic processes. [Extracted from the article]

Marine dimethylsulfide (DMS) is an important source of natural sulfur to the atmosphere, with potential implications for the Earth's radiative balance. Coral reefs are important regional sources of DMS, yet their contribution is not accounted for in global DMS climatologies or in model simulations. This study accounts for coral-reef-derived DMS and investigates its influence on the atmosphere of the Great Barrier Reef (GBR), Australia, using the Australian Community Climate and Earth System Simulator Atmospheric Model version 2 (ACCESS-AM2). A climatology of seawater surface DMS (DMSw) concentration in the GBR and an estimate of direct coral-to-air DMS flux during coral exposure to air at low tide are incorporated into the model, increasing DMS emissions from the GBR region by 0.02 Tg yr-1. Inclusion of coral-reef-derived DMS increased annual mean atmospheric DMS concentration over northeastern Australia by 29%, contributing to an increase in gas-phase sulfate aerosol precursors of up to 18% over the GBR. The findings suggest that the GBR is an important regional source of atmospheric sulfur, with the potential to influence local-scale aerosol-cloud processes. However, no influence on sulfate aerosol mass or number concentration was detected, even with a reduction in anthropogenic sulfur dioxide emissions, indicating that DMS may not significantly influence the regional atmosphere at monthly, annual or large spatial scales. Further research is needed to improve the representation of coral-reef-derived DMS in climate models and determine its influence on local, sub-daily aerosol-cloud processes, for which observational studies suggest that DMS may play a more important role. [ABSTRACT FROM AUTHOR]

Observation of coral spawning times is valuable to detect spawning patterns and identify the potential mechanisms behind coral reproduction. Although large amount of data on global coral spawning records have become available over the past decades, information on coral spawning in the northern South China Sea remains scarce. In this study, we investigated the spawning patterns of scleractinian corals in Luhuitou fringing reef, Hainan Island, China, from 2009 to 2021 in relation to lunar cycles (month and day). The spawning times of 22 coral species from five genera (Acropora, Montipora, Platygyra, Dipsastraea, and Galaxea) within three families (Acroporidae, Merulinidae, and Euphylliidae) were recorded, with spawning occurring from lunar February to May 2009-2021. Recorded spawning events started at a period of increasing seawater temperature. Acropora, the most documented genus, spawned between lunar February and April, but primarily in lunar March. Importantly, the spawning time of Acropora was delayed for one lunar month in 2016 most likely due to a rapid decrease in monthly mean seawater temperature in lunar February. Spawning lunar days before, on or after full moon of corals in the Luhuitou Reef, including those of the Acropora species, were highly variable between years even for the same species. No predictable pattern of spawning times can thus be detected. Nonetheless, our results fill up an information gap on coral spawning patterns in the northern South China Sea that may be useful for further understanding of the reproductive biology of scleractinian corals throughout the Indo-West Pacific. [ABSTRACT FROM AUTHOR]

Introduction: In 2023, a comprehensive survey was conducted at Qiziwan National Marine Park (QZW) to assess marine environmental variables, coral communities, and ecosystem parameters. This study aimed to evaluate the current state of coral ecosystems across different regions within the park. Methods: The survey covered 19 sampling stations distributed among four regions: Xiaojiao Park, Zhongjiao Park, Dajiao Park, and Shayutang Village. Various marine environmental parameters were measured, and coral species were identified and recorded. Results: A total of 67 species of reef-building corals belonging to 25 genera were identified. Dominant species included Porites lutea, Goniopora columna, Platygyra sinensis, Favites flexuosa, Galaxea fascicularis, and Acropora millepora. Coral coverage was found to be low at Xiaojiao Park, with high levels of turbidity and dissolved inorganic nitrogen, likely due to the nearby Changhua Port. Dajiao Park's sandy substrate made it unsuitable for coral survival. In contrast, Zhongjiao Park and Shayutang Village exhibited the best coral ecosystems. Redundancy analysis indicated that turbidity and substrate types were significant factors influencing coral distribution. Discussion: The live coral coverage at Xiaojiao Park, parts of Zhongjiao Park, and Dajiao Park declined from 14.03% in 2017 to 11.73% in 2023. This decline is potentially attributed to frequent marine construction and land use changes. Anthropogenic disturbances appear to have worsened environmental conditions, undermining coral reef survival at QZW. [ABSTRACT FROM AUTHOR]

Cyanobacteria of the genus Trichodesmium form extensive blooms that supply new N to nutrient-poor marine ecosystems. Yet little is known about what eats Trichodesmium. In this laboratory study, we show that one of the greatest threats to coral reefs, predatory crown-of-thorns starfish (CoTS), Acanthaster sp., completes their larval phase feeding solely on Trichodesmium. We observed Trichodesmium erythraeum CMP1985 in the stomachs of larvae using florescence microscopy and traced the assimilation of nitrogen from labeled trichomes into larval tissues using stable isotopes. Some larvae fed T. erythraeum were morphologically ready to become benthic juveniles after 19 days. Given that Trichodesmium can be food for CoTS, reported increases in Trichodesmium could be a driving factor in the heightened frequency of CoTS population irruptions that have devastated coral reefs in past decades. Future studies could test this through investigating the diets of wild larvae and incorporating Trichodesmium abundance into models of CoTS population dynamics. [ABSTRACT FROM AUTHOR]

The algal endosymbiont Durusdinium trenchii enhances the resilience of coral reefs under thermal stress. D. trenchii can live freely or in endosymbiosis, and the analysis of genetic markers suggests that this species has undergone whole-genome duplication (WGD). However, the evolutionary mechanisms that underpin the thermotolerance of this species are largely unknown. Here, we present genome assemblies for two D. trenchii isolates, confirm WGD in these taxa, and examine how selection has shaped the duplicated genome regions using gene expression data. We assess how the free-living versus endosymbiotic lifestyles have contributed to the retention and divergence of duplicated genes, and how these processes have enhanced the thermotolerance of D. trenchii. Our combined results suggest that lifestyle is the driver of post-WGD evolution in D. trenchii, with the free-living phase being the most important, followed by endosymbiosis. Adaptations to both lifestyles likely enabled D. trenchii to provide enhanced thermal stress protection to the host coral. [ABSTRACT FROM AUTHOR]

The National Oceanic and Atmospheric Administration's (NOAA) Center for Satellite Applications and Research (STAR) facilitates and enables societal benefits from satellite oceanography, supporting operational and experimental satellite missions, developing new and improved ocean observing capabilities, engaging users by developing and distributing fit-for-purpose data, applications, tools, and services, and curating, translating, and integrating diverse data products into information that supports informed decision making. STAR research, development, and application efforts span from passive visible, infrared, and microwave observations to active altimetry, scatterometry, and synthetic aperture radar (SAR) observations. These efforts directly support NOAA's operational geostationary (GEO) and low Earth orbit (LEO) missions with calibration/validation and retrieval algorithm development, implementation, maintenance, and anomaly resolution, as well as leverage the broader international constellation of environmental satellites for NOAA's benefit. STAR's satellite data products and services enable research, assessments, applications, and, ultimately, decision making for understanding, predicting, managing, and protecting ocean and coastal resources, as well as assessing impacts of change on the environment, ecosystems, and climate. STAR leads the NOAA Coral Reef Watch and CoastWatch/OceanWatch/PolarWatch Programs, helping people access and utilize global and regional satellite data for ocean, coastal, and ecosystem applications. [ABSTRACT FROM AUTHOR]

The Brazilian marine biogeographical province (SW Atlantic) hosts coral and rocky reefs that cover ~27 degrees of latitude and are distributed along a relatively narrow continental shelf and four oceanic islands and archipelagos. The broad gradients in temperature, productivity and salinity shape patterns of biodiversity and lead to distinct local communities within the province. Although existing research has helped to unveil spatiotemporal patterns of marine diversity in this province, data availability and scale have limited broader inferences on the main processes shaping biodiversity. Here, we bring together 16 datasets (n = 11 for reef fish, n = 5 for benthic reef organisms) comprising 22 years of research conducted across most of the Brazilian province. These datasets are unprecedented in terms of temporal, spatial, and taxonomic coverage. For example, eight datasets (six for reef fish, two for benthos) span seven (fish monitoring in Rio Grande do Norte) to 18 years (fish monitoring in Arraial do Cabo, Rio de Janeiro) of survey data. Also, these datasets contain data collected in priority areas for conservation in the Brazilian province, such as the Abrolhos Bank and the Trindade island. The data comprise detection and fish count/benthic cover data for 24,498 sampling events deployed at 55 locations, formatted according to the Darwin Core Standard, being therefore interoperable with other existing datasets. The 11 fish datasets comprise the detection and counting of 361 fish taxa (312 identified at species level, 49 identified at genus, subfamily and family) from 178 genera, 71 families and 2 classes (Teleostei and Elasmobranchii). The five benthic datasets comprise the description of the detection and cover of 81 taxa, 82 genera, 68 families, 15 classes, and 4 kingdoms (Animalia, Bacteria, Plantae, Chromista). By making this an open-access resource, we share with the public the result of two decades of federal and state funding for scientific research on Brazilian reefs. [ABSTRACT FROM AUTHOR]

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