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Climate change is reorganizing the planet's biodiversity, necessitating proactive management of species and habitats based on spatiotemporal predictions of distributions across climate scenarios. In marine settings, climatic changes will predominantly manifest via warming, ocean acidification, deoxygenation, and changes in hydrodynamics. Lophelia pertusa, the main reef-forming coral present throughout the deep Atlantic Ocean (>200 m), is particularly sensitive to such stressors with stark reductions in suitable habitat predicted to accrue by 2100 in a business-as-usual scenario. However, with new occurrence data for this species along with higher-resolution bathymetry and climate data, it may be possible to locate further climatic refugia. Here, we synthesize new and published biogeographic, geomorphological, and climatic data to build ensemble, multi-scale habitat suitability models for L. pertusa on the continental margin of the southeast United States (SEUS). We then project these models in two timepoints (2050, 2100) and four climate change scenarios to characterize the occurrence probability of this critical cold-water coral (CWC) habitat now and in the future. Our models reveal the extent of reef habitat in the SEUS and corroborate it as the largest currently known essentially continuous CWC reef province on earth, and also predict abundance of L. pertusa to identify key areas, including those outside areas currently protected from bottom-contact fishing. Drastic reductions in L. pertusa climatic suitability index emerged primarily after 2050 and were concentrated at the shallower end (

Abstract The 1771 Meiwa tsunami which struck the southern Ryukyu Islands (Sakishima Islands) had greater than 22 m run-up height, leaving about 12,000 casualties in its wake. At many places, the tsunami inundation or lack of inundation is well recorded in historical documents. Several tsunami source models have been proposed for this event using historical records as constraints of tsunami calculations. Nevertheless, the source model remains under discussion. This study re-evaluated the tsunami wave source model of the 1771 Meiwa tsunami using high-resolution (10 m mesh) bathymetric and topographical data for tsunami calculation, the latest historical record dataset, and seismological knowledge. Results demonstrated that a tsunami earthquake along the southern Ryukyu Trench was the likely cause of the 1771 event. However, it is noteworthy that assumption of a large slip with 30 m is necessary for a shallow and narrow region (fault depth = 5 km, fault width = 30 km, Mw = 8.49) of the plate boundary in the Ryukyu Trench, which is far larger than previously thought. This requirement of very large initial water level change at the source might involve not only the fault rupture along the plate boundary but also deformation by splay faults, inelastic deformation of unconsolidated sediments near the trench axis, and/or giant submarine landslides. Results also show that the effects of fault parameters on the run-up were quite different depending on the offshore coral reef width. This phenomenon strongly constrained the fault width to 30 km. Our tsunami ray tracing analysis further revealed the effects of bathymetry on tsunami propagation. It is noteworthy that meter-long huge tsunami boulders tend to be distributed along the specific coasts at which the tsunami was concentrated by bathymetric effects. This finding suggests that past tsunamis, including the 1771 event, might have affected the specific coral reefs on Sakishima Islands repeatedly, which is crucially important for understanding the heterogeneous distribution of tsunami boulders. This feature might also be useful to elucidate the effects of large tsunamis on the corals and reefs because a direct comparison of coral reefs that are damaged and not damaged by tsunami waves is testable in narrow areas in the case of the Sakishima Islands.

Abstract The persistence of diverse yet threatened ecosystems like coral reefs will require urgent action underpinned by effective assessments of resilience. Resilience potential assessments are commonly used to identify coral reefs likely to be more resilient to disturbances, based on indicators of state and function. Assessments are intended to support decision‐making, therefore, using principles from decision‐science and indicator design theory, we evaluated the selection, design and analysis of indicators from 68 resilience potential assessments conducted between 2008 and 2022. These principles include justifying and testing indicators and aggregation approaches, representing key parts of the ecosystem, considering uncertainty and meaningful normalisation of indicators. Although a broad range of indicators were typically evaluated, assessments rarely present structured processes to guide and justify indicator selection, such as selection criteria and conceptual models of ecosystem function. We also found that certain key ecosystem components that confer resilience were represented by indicators in almost all assessments, such as corals, herbivory, competition and reef structure. Other factors were rarely considered, such as abundance and diversity of key fish trophic groups other than herbivores, for example groupers and corallivores, other aspects of biodiversity and competitive interactions with corals. Reference points used to translate variables into resilience indicators were typically derived from the data, such as the highest indicator value of assessed sites. Ecologically meaningful thresholds, such as collapse or historic levels, were used less often as references. In most cases, indicators were not tested or validated against independent data, uncertainties were not presented, and there was a tendency to simplify results into composite indices to rank sites, without justifying aggregation methods. Despite resource constraints, most resilience potential assessments collect quantitative data that are useful for coral reef management. However, the shortcomings identified can make indicator interpretation difficult, limiting the capacity to predict the resilience of the system and support decisions. Implementation of robust approaches drawn from indicator design and selection theory can help strengthen resilience potential assessments of coral reefs and other ecosystems, ultimately improving the prospects of conservation.

Abstract As ocean temperatures continue to rise, coral bleaching events around the globe are becoming stronger and more frequent. High-resolution temperature data is therefore critical for monitoring reef conditions to identify indicators of heat stress. Satellite and in situ measurements have historically been relied upon to study the thermal tolerances of coral reefs, but these data are quite limited in their spatial and temporal coverage. Ocean circulation models could provide an alternative or complement to these limited data, but a thorough evaluation against in situ measurements has yet to be conducted in any Pacific Islands region. Here we compared subsurface temperature measurements around the nearshore Main Hawaiian Islands (MHI) from 2010 to 2017 with temperature predictions from an operational Regional Ocean Modeling System (ROMS) to evaluate the potential utility of this model as a tool for coral reef management. We found that overall, the ROMS reanalysis presents accurate subsurface temperature predictions across the nearshore MHI region and captures a significant amount of observed temperature variability. The model recreates several temperature metrics used to identify coral heat stress, including predicting the 2014 and 2015 bleaching events around Hawaiʻi during the summer and fall months of those years. The MHI ROMS simulation proves to be a useful tool for coral reef management in the absence of, or to supplement, subsurface and satellite measurements across Hawaiʻi and likely for other Pacific Island regions.

The 1771 Meiwa tsunami which struck the southern Ryukyu Islands (Sakishima Islands) had greater than 22 m run-up height, leaving about 12,000 casualties in its wake. At many places, the tsunami inundation or lack of inundation is well recorded in historical documents. Several tsunami source models have been proposed for this event using historical records as constraints of tsunami calculations. Nevertheless, the source model remains under discussion. This study re-evaluated the tsunami wave source model of the 1771 Meiwa tsunami using high-resolution (10 m mesh) bathymetric and topographical data for tsunami calculation, the latest historical record dataset, and seismological knowledge. Results demonstrated that a tsunami earthquake along the southern Ryukyu Trench was the likely cause of the 1771 event. However, it is noteworthy that assumption of a large slip with 30 m is necessary for a shallow and narrow region (fault depth = 5 km, fault width = 30 km, Mw = 8.49) of the plate boundary in the Ryukyu Trench, which is far larger than previously thought. This requirement of very large initial water level change at the source might involve not only the fault rupture along the plate boundary but also deformation by splay faults, inelastic deformation of unconsolidated sediments near the trench axis, and/or giant submarine landslides. Results also show that the effects of fault parameters on the run-up were quite different depending on the offshore coral reef width. This phenomenon strongly constrained the fault width to 30 km. Our tsunami ray tracing analysis further revealed the effects of bathymetry on tsunami propagation. It is noteworthy that meter-long huge tsunami boulders tend to be distributed along the specific coasts at which the tsunami was concentrated by bathymetric effects. This finding suggests that past tsunamis, including the 1771 event, might have affected the specific coral reefs on Sakishima Islands repeatedly, which is crucially important for understanding the heterogeneous distribution of tsunami boulders. This feature might also be useful to elucidate the effects of large tsunamis on the corals and reefs because a direct comparison of coral reefs that are damaged and not damaged by tsunami waves is testable in narrow areas in the case of the Sakishima Islands. [ABSTRACT FROM AUTHOR]

Background: Bypass surgery in severe aorto-iliac calcifications is a complex procedure. Aortic clamping can be highly risky and endovascular approach can be unsuccessful. We report our experience describing three cases of chronic mesenteric ischemia. In all three cases the preoperative computed tomography angiography revealed an ostial occlusion of the celiac trunk and of the superior mesenteric artery (SMA), a coral reef abdominal aorta, and severe calcification of the iliac arteries. An antegrade aorto-mesenteric bypass using a hybrid clampless anastomosis on the supraceliac aorta was performed. Results: The procedures were performed via laparotomy. We carried out the exposure of the anterior supraceliac aorta limited to the zone without major calcifications; then we performed a side-to-end media-adventitial anastomosis between the supraceliac aorta and a Dacron graft 7 mm without any arteriotomy or clamping. The proximal graft and the aortic anastomosis site were punctured using a 18 G needle. An introducer was then positioned over a wire through the prosthetic graft and pushed into the aorta. Balloon expandable covered stenting to open and stabilize the anastomosis site was performed. Finally, the graft was tunneled to the SMA, and an end-to-side anastomosis was performed. The postoperative courses were uneventful, and the patients were promptly discharged. The follow-up, which in the first case is 4 years, showed the complete patency of the graft in each of the cases treated. Conclusions: The hybrid clampless anastomosis appears to be safe and useful in cases of severe aortic calcification. [ABSTRACT FROM AUTHOR]

Endozoicomonas is globally the most prevalent and consistently found bacterial genus associated with Cnidaria; strains of Endozoicomonas are known to codiversify with their coral hosts, and they are widely presumed to be key mutualists. A high abundance of Endozoicomonas in corals is associated with a decreased capacity to adjust to environmental change as well as with life history trade-offs. In other marine host–microbe systems, such as clams and fish, Endozoicomonas is a known parasite and pathogen. Genomic characteristics – such as genome size and structure, and the presence of eukaryote-like proteins and effectors – do not support the view that Endozoicomonas is an obligate and exclusive coral mutualist but may suggest a diverse and potentially intracellular lifestyle, including commensalism, parasitism, or pathogenicity. Stony corals are poster child holobionts due to their intimate association with diverse microorganisms from all domains of life. We are only beginning to understand the diverse functions of most of these microbial associates, including potential main contributors to holobiont health and resilience. Among these, bacteria of the elusive genus Endozoicomonas are widely perceived as beneficial symbionts based on their genomic potential and their high prevalence and ubiquitous presence in coral tissues. Simultaneously, evidence of pathogenic and parasitic Endozoicomonas lineages in other marine animals is emerging. Synthesizing the current knowledge on the association of Endozoicomonas with marine holobionts, we challenge the perception of a purely mutualistic coral– Endozoicomonas relationship and propose directions to elucidate its role along the symbiotic spectrum. [ABSTRACT FROM AUTHOR]

Marine protected areas (MPAs) can be a useful tool to manage coastal ecosystems, delivering both social and ecological outcomes. However, in many instances, relevant data is missing to conduct proper impact assessments, which is key to identifying ecological and social synergies and potential trade‐offs, and to adapting management according to local objectives. The ecological effects of an MPA established in Palawan, Philippines, in 2016, were assessed. The most common species targeted by fisheries were identified by local fishers. Species size and number were collected through underwater visual census with n = 288 belt transects assigned in different sites and locations to ensure to provide both protected and control (fished) sites for the MPA assessment, and baseline data for three new MPAs that were created in 2022. 91 coral‐reef fish species belonging to 12 families were recorded. Mixed effect linear regression was used to compare target fish populations in protected and control sites. Compared to control locations, 5 years after its implementation, the MPA showed significantly higher species richness, abundance, mean size, and biomass while no significant difference was found on the average trophic level between MPA and control sites. Monitoring the early effects of an MPA and collecting baseline data prior the implementation of an MPA network is key for adaptive management. [ABSTRACT FROM AUTHOR]

Islands have been used as model systems to study ecological and evolutionary processes, and they provide an ideal set‐up for validating new biodiversity monitoring methods. The application of environmental DNA metabarcoding for monitoring marine biodiversity requires an understanding of the spatial scale of the eDNA signal, which is best tested in island systems. Here, we investigated the variation in Actinopterygii and Elasmobranchii species composition recovered from eDNA metabarcoding along a gradient of distance‐to‐reef in four of the five French Scattered Islands in the Western Indian Ocean. We collected surface water samples at an increasing distance from reefs (0 m, 250 m, 500 m, 750 m). We used a metabarcoding protocol based on the 'teleo' primers to target marine reef fishes and classified taxa according to their habitat types (benthic or pelagic). We investigated the effect of distance‐to‐reef on β diversity variation using generalised linear mixed models and estimated species‐specific distance‐to‐reef effects using a model‐based approach for community data. Environmental DNA metabarcoding analyses recovered distinct fish species compositions across the four inventoried islands and variations along the distance‐to‐reef gradient. The analysis of β‐diversity variation showed significant taxa turnover between the eDNA samples on and away from the reefs. In agreement with a spatially localised signal from eDNA, benthic species were distributed closer to the reef than pelagic ones. Our findings demonstrate that the combination of eDNA inventories and spatial modelling can provide insights into species habitat preferences related to distance‐to‐reef gradients at a small scale. As such, eDNA can not only recover large compositional differences among islands but also help understand habitat selection and distribution of marine species at a finer spatial scale. [ABSTRACT FROM AUTHOR]

Throughout the Caribbean region, coastal areas are of vital importance for national incomes from the tourism industry. However, accelerated coastal development has impacted the coastal ecosystems, including the beaches, and deterioration of the shore results from cumulative impacts on both marine and coastal ecosystems. It is essential to identify the areas that need special attention for targeted management plans and actions, especially in areas with high anthropogenic pressure. This research proposes an integrated assessment of the conservation state of shore and coastal ecosystems in the Puerto Morelos National Reef Park (PNAPM) in the Mexican Caribbean, through the spatial monitoring of key parameters. A Geographic Information System (GIS) was employed to analyze the land use on the shore, foredune condition, morphological characteristics of the beaches, shoreline evolution, and the condition of coral reefs and seagrass meadows. The analysis identified the most critical areas in relation to shore deterioration and priority areas for the preservation of ecosystems. The spatial data obtained for the PNAPM can serve as a basis for ongoing shore monitoring, and targeted management actions through the designation of areas that require either preservation or ecosystem restoration practices. This methodology can be applied to other reef systems in the Caribbean. [ABSTRACT FROM AUTHOR]

Coral reefs are effective natural flood barriers that protect adjacent coastal communities. As the need to adapt to rising sea levels, storms, and environmental changes increases, reef restoration may be one of the best tools available to mitigate coastal flooding along tropical coastlines, now and in the future. Reefs act as a barrier to incoming short-wave energy but can amplify low-frequency infragravity waves that, in turn, drive coastal flooding along low-lying tropical coastlines. Here, we investigate whether the spacing of reef restoration elements can be optimized to maximize infragravity wave energy dissipation while minimizing the number of elements—a key factor in the cost of a restoration project. With this goal, we model the hydrodynamics of infragravity wave dissipation over a coral restoration or artificial reef, represented by a canopy of idealized hemispherical roughness elements, using a three-dimensional Navier–Stokes equations solver (OpenFOAM). The results demonstrate that denser canopies of restoration elements produce greater wave dissipation under larger waves with longer periods. Wave dissipation is also frequency-dependent: dense canopies remove wave energy at the predominant wave frequency, whereas sparse canopies remove energy at higher frequencies, and hence are less efficient. We also identify an inflection point in the canopy density–energy dissipation curve that balances optimal energy losses with a minimum number of canopy elements. Through this work, we show that there are an ideal number of restoration elements per across-shore meter of coral reef flat that can be installed to dissipate infragravity wave energy for given incident heights and periods. These results have implications for designing coral reef restoration projects on reef flats that are effective both from a coastal defense and costing standpoint. [ABSTRACT FROM AUTHOR]

Coral reefs provide ideal habitats for crabs and various living organisms, offering crevices, sandy bottoms, and a rich diversity of resources. Mu Koh Tao, located on the western Gulf of Thailand, boasts vibrant coral reefs and potentially high crab biodiversity. However, coral bleaching due to climate change may impact this biodiversity. This study investigates the diversity, abundance, distribution, and community structure of crabs in coral reefs around Koh Tao and Koh Nang Yuan, including 11 sampling stations with varying levels of coral bleaching. A total of 47 crab species from 34 genera and 14 families were identified. The most abundant and notable species were Trapezia cymodoce, Tetralia nigrolineata, and Tetralia rubridactyla. Additionally, two species were newly recorded in the Gulf of Thailand, and seven species were potentially first reports for Thailand. Rare species dominated, comprising 82.98% of the total. Shark Island had the highest Shannon-diversity and species richness indices, at 2.43 and 5.53, respectively, underscoring its ecological importance. The crab community structure varied with the severity of coral bleaching and the diversity of associated organisms. An in-depth study compared the abundance of coral crabs in healthy versus bleached corals, revealing that Tr. cymodoce did not inhabit bleached Pocillopora damicornis, while Te. nigrolineata was found in both healthy and bleached Acropora hyacinthus, with densities of 23.81 and 7.24 individuals per square meter, respectively. These findings suggest that coral crabs can serve as indicators of climate change-induced coral bleaching and associated habitat loss, highlighting the need for conservation efforts to protect these ecosystems. [ABSTRACT FROM AUTHOR]

Black band disease (BBD) is one of the oldest recognized diseases of sderactinian corals. This disease is little known on the variation of progression rates across relatively small spatial scales and how local variations in the environment can impact prevalence and spread. The purpose of this study was to explore the progression of BBD on genus Montipora in relation to spatio-temporal environmental parameters in two islands of the Seribu Islands, North Jakarta, Indonesia during dry season and rainy season. Monthly underwater pictures were taken for determining the progress of disease level. Interestingly, the progression rate of the disease recorded at Pramuka Island was higher (8.10 cm² day-1) than the one at Pari Island (3.79 cm² day-1). In Pramuka Island, the infected corals had almost 89% of the dead surface, compared to only 68% at Pari Island. Similar to other studies in the region, we confirmed that the disease progressed faster during the dry season, where the environmental parameters, such as temperature, light intensity, and phosphate, were starting to increase, while total organic matter, current flow rates, and turbidity were lower. Progression of the disease was significantly different between seasons (p<0.001), but not between sites (p=0.118). Therefore, the progress of BBD has a higher impact at the more populated Pramuka island than at the less populated Pari Island, in addition to the influence of environmental parameters on coral vulnerability to diseases. [ABSTRACT FROM AUTHOR]

Because they serve as the main architects of coral reefs, the distribution and abundance of stony coral species have major impacts on other associated community members. Thus, coral diseases can have significant cascading effects throughout the ecosystem. Stony coral tissue loss disease (SCTLD) is the most recent of many diseases documented to impact Caribbean stony corals. SCTLD is known to impact over 20 species of reef-building corals and can cause complete colony mortality of large corals in only one month. Among the coral species impacted are those occupied as cleaning stations by Caribbean cleaner gobies. This study examined the persistence of these gobies on living coral cleaning stations where SCTLD was most recently or not yet affected (emergent), recently established (epidemic), and well-established (endemic),. Timed surveys were conducted at nine reefs in the U.S. Virgin Islands between October 2019 and March 2021. Study sites were surveyed both before and after the outbreak/ establishment of SCTLD where possible. Monitoring sites were established at six reefs by tagging 25 live coral cleaning stations at each of two endemic and two epidemic sites and 50 cleaning stations at each of two emergent sites. Goby abundance at each site was monitored at least five times from March 2020 to April 2021. Timed surveys found cleaner goby abundance was 50% lower in the endemic zone compared to epidemic and emergent zones. Overall, goby abundance declined on tagged cleaning stations throughout the course of this study at all sites. However, overall goby density within monitored areas remained stable across most sites from the beginning to the end of the study. One emergent site experienced a two-fold increase in goby density and one epidemic site experienced a decline in goby density. This suggests that gobies are remaining at the site but may be abandoning live coral cleaning stations as the individual colonies are affected by SCTLD. Given the benefit cleaner gobies have on local coral reef fishes, changes in cleaning activity associated with coral disease have the potential to negatively impact Caribbean reef fish communities. [ABSTRACT FROM AUTHOR]

Waves and currents are responsible for sedimentmovement around and off coral reefs, affecting reef growth at both geological and modern timescales. Given the wide distribution and limited hydrodynamic information of reefs in the South China Sea, we carried out observations on tidal-cycle hydrodynamics in the Nansha Islands with tripod stationary instruments on the seafloor in order to fill the gap in our understanding of these processes. It was found that the magnitudes of near-bed orbital velocity were comparable with that of the mean tidal current, despite generally calm wave conditions. Waves dominated the combined wave-current skin-friction shear velocities acting on reef sediment, which were significantly higher than those generated by currents alone. Due to the large physical roughness of reef, drag coefficient and hydrodynamic roughness length estimated from logarithmic velocity profiles were two orders of magnitude higher than that in macro-tidal-estuary or inner shelf areas covered with siliceous muds or sands. The combined sinusoidal wave and asymmetric tidal current, along with the physical reef roughness, shaped velocity profile structures in the bottom boundary layer, which exhibited a logarithmic profile during the flood tide and a potential flow during the ebb. In absence of wave breaking, strong turbulence dissipation was observed across the rough reef, promoting strong mixing of water, which is crucial for delivering nutrients for coral growth. These findings imply the need to consider the unique characteristics of rough reef structure and combined effects of waves and currents to model the hydrodynamics in reef environment correctly. This understanding is critical for predicting energy and material transport in reef environments, which is essential for maintaining healthy coral ecosystems, and opens new paths for managing and preserving coral reefs in the face of environmental change. [ABSTRACT FROM AUTHOR]

PCR‐based high‐throughput sequencing has permitted comprehensive resolution analyses of zooplankton diversity dynamics. However, significant methodological issues still surround analyses of complex bulk community samples, not least as in prevailing PCR‐based approaches. Marine drifting animals—zooplankton—play essential ecological roles in the pelagic ecosystem, transferring energy and elements to higher trophic levels, such as fishes, cetaceans and others. In the present study, we collected 48 size‐fractionated zooplankton samples in the vicinity of a coral reef island with environmental gradients. To investigate the spatiotemporal dynamics of zooplankton diversity patterns and the effect of PCR amplification biases across these complex communities, we first took metatranscriptomics approach. Comprehensive computational analyses revealed a clear pattern of higher/lower homogeneity in smaller/larger zooplankton compositions across samples respectively. Our study thus suggests changes in the role of dispersal across the sizes. Next, we applied in silico PCR to the metatranscriptomics datasets, in order to estimate the extent of PCR amplification bias. Irrespective of stringency criteria, we observed clear separations of size fraction sample clusters in both metatranscriptomics and in silico datasets. In contrast, the pattern—smaller‐fractioned communities had higher compositional homogeneity than larger ones—was observed in the metatranscriptomics data but not in the in silico datasets. To investigate this discrepancy further, we analysed the mismatches of widely used mitochondrial CO1 primers and identified priming site mismatches likely driving PCR‐based biases. Our results suggest the use of metatranscriptomics or, although less ideal, redesigning the CO1 primers is necessary to circumvent these issues. [ABSTRACT FROM AUTHOR]

Aim: Climate change is affecting the geographic distributions of many species and researchers are increasingly relying on species distribution models (SDMs) to forecast species' redistributions under climate change. Such modelling studies, however, often ignore biotic interactions that shape species' geographic ranges. This is especially problematic for coral reefs, which host a high diversity of species and interactions. We tested how biotic interactions affect the distribution patterns of obligate coral‐dwelling Trapezia crabs. Location: Global coastal ocean. Time Period: 2000–2014, 2040–2050, 2090–2100. Major Taxa Studied: Corals and coral‐dwelling Trapezia crabs. Methods: We determined the symbiotic relationships between 22 crab species in the genus Trapezia and corals via field survey and extensive literature review. We first developed SDMs for coral and crab species using exclusively abiotic variables (abiotic‐only models for corals and crabs). Then we constructed a second set of models where we accounted for coral distributions into crab predictions by combining model predictions for the two taxa a posteriori (abiotic‐plus‐biotic models for crabs only). Results: We obtained 30 commonly accepted coral‐crab symbiotic relationships from nine Trapezia crab and six stony coral species. The abiotic‐only model predictions showed that six corals may lose approximately one‐sixth of suitable ranges under RCP 8.5 in 2040–2050. The two types of models for crabs yielded largely different habitat suitability predictions and accounting for biotic interactions into SDM predictions exacerbates the predicted impacts of climate change on coral‐dwelling crabs. Main Conclusions: Our results show large discrepancies in crab spatial distribution patterns with and without accounting for symbiotic interactions. Our findings highlight the important role of modeller's decision on accounting for biotic interactions when predicting the geographical ranges of coral‐dwelling species, with important implications for designing future conservation and management strategies for marine species. [ABSTRACT FROM AUTHOR]

Climate change is the primary threat to coral reefs, causing catastrophic coral mortality on a global scale. Stressors such as ocean acidification limit calcium carbonate availability needed to build skeletons. A wealth of research has shown that climate stressors impair the ability of coral to produce and maintain their skeletons, thereby disrupting functions critical to maintaining coral health as well as threatening the ecologically significant framework for reef building. There are natural marginal and extreme environments however, where coral reefs thrive despite unfavourable conditions. These habitats provide a natural long-term setting to examine the impact of multiple interacting climate change factors on corals and understand the adaptations required by corals to inhabit these conditions. We review studies of coral skeletogenesis in extreme and marginal environments, with a particular focus on mangrove habitats due to their natural fluctuations in temperature, pH and oxygen, analogous to those projected under climate change models. The changes in coral skeletal morphology under stress are described as are the techniques used to visualise these changes. In marginal and extreme environments, corals experience lower calcification rates and produce more porous, less robust skeletons whilst maintaining normal rates of linear extension, suggesting the integrity of coral skeletons are likely to be threatened under future ocean conditions. The biomineralisation processes of corals inhabiting extreme and marginal environments remains an underexplored area of research and has the potential to yield valuable insights into how corals might adapt to climate change and the mechanisms that underlie their resilience to global environmental change. [ABSTRACT FROM AUTHOR]

Tropical coastal benthic communities will change in species composition and relative dominance due to global (e.g., increasing water temperature) and local (e.g., increasing terrestrial influence due to land-based activity) stressors. This study aimed to gain insight into possible trajectories of coastal benthic assemblages in Raja Ampat, Indonesia, by studying coral reefs at varying distances from human activities and marine lakes with high turbidity in three temperature categories (<31 °C, 31-32 °C, and >32 °C). The benthic community diversity and relative coverage of major benthic groups were quantified via replicate photo transects. The composition of benthic assemblages varied significantly among the reef and marine lake habitats. The marine lakes <31 °C contained hard coral, crustose coralline algae (CCA), and turf algae with coverages similar to those found in the coral reefs (17.4-18.8% hard coral, 3.5-26.3% CCA, and 15-15.5% turf algae, respectively), while the higher temperature marine lakes (31-32 °C and >32 °C) did not harbor hard coral or CCA. Benthic composition in the reefs was significantly influenced by geographic distance among sites but not by human activity or depth. Benthic composition in the marine lakes appeared to be structured by temperature, salinity, and degree of connection to the adjacent sea. Our results suggest that beyond a certain temperature (>31 °C), benthic communities shift away from coral dominance, but new outcomes of assemblages can be highly distinct, with a possible varied dominance of macroalgae, benthic cyanobacterial mats, or filter feeders such as bivalves and tubeworms. This study illustrates the possible use of marine lake model systems to gain insight into shifts in the benthic community structure of tropical coastal ecosystems if hard corals are no longer dominant. [ABSTRACT FROM AUTHOR]

That coral reefs are in decline worldwide, particularly in the Caribbean, will come as no surprise. This decades-long decline has reached a potential tipping point as the weight of the effects of climate change have come decidedly to bear on the planet's most diverse marine ecosystem. Whether coral reefs can persist without restorative intervention is debatable, which has prompted a surge in coral reef restoration projects focusing primarily on the cultivation and transplantation of coral fragments onto degraded reefs. But that widespread approach does little to address the underlying causes of coral loss, one of which is the proliferation of macroalgae that are deleterious to corals. An emerging solution to this problem is the enhancement of herbivory on coral reefs through improved management of herbivores, artificial enhancement of herbivore settlement, or their mariculture and subsequent stocking. This review explores the nuances of the biology of wellstudied Caribbean coral reef herbivores (fishes, sea urchins, and crabs) as it relates to their mariculture and investigates the promise of herbivore stocking onto coral reefs as a restoration strategy. Fish, urchin, and crab herbivores differ appreciably in life histories, which confers advantages and disadvantages with respect to their mariculture and effectiveness as grazers. Mariculture of herbivorousmarine fish for reef restoration is essentially non-existent so the reestablishment of grazing fish abundance on coral reefs focuses primarily on their protection through fishery regulations, but only at a fewlocations in the Caribbean. Mariculture of herbivorous urchins and crabs for restoration purposes is in its infancy, but promising especially for crabs whose larval rearing is less difficult. Perhaps the biggest challenge for the mariculture of either taxon is "scaling-up" from research settings to large-scale mariculture needed for stocking. Numerous studies extol the benefits of functional redundancy and complementarity for coral reef ecosystem stability, but whether this principal applies to the restoration of grazing function is untested. We identify gaps in our knowledge of best practices for the restoration of grazing function on coral reefs and conclude with some practical guidance on the establishment of targets for macroalgal reduction, alongwith strategic advice on grazer stocking in a given reef habitat. [ABSTRACT FROM AUTHOR]

The persistence of diverse yet threatened ecosystems like coral reefs will require urgent action underpinned by effective assessments of resilience. Resilience potential assessments are commonly used to identify coral reefs likely to be more resilient to disturbances, based on indicators of state and function.Assessments are intended to support decision‐making, therefore, using principles from decision‐science and indicator design theory, we evaluated the selection, design and analysis of indicators from 68 resilience potential assessments conducted between 2008 and 2022. These principles include justifying and testing indicators and aggregation approaches, representing key parts of the ecosystem, considering uncertainty and meaningful normalisation of indicators.Although a broad range of indicators were typically evaluated, assessments rarely present structured processes to guide and justify indicator selection, such as selection criteria and conceptual models of ecosystem function. We also found that certain key ecosystem components that confer resilience were represented by indicators in almost all assessments, such as corals, herbivory, competition and reef structure. Other factors were rarely considered, such as abundance and diversity of key fish trophic groups other than herbivores, for example groupers and corallivores, other aspects of biodiversity and competitive interactions with corals. Reference points used to translate variables into resilience indicators were typically derived from the data, such as the highest indicator value of assessed sites. Ecologically meaningful thresholds, such as collapse or historic levels, were used less often as references. In most cases, indicators were not tested or validated against independent data, uncertainties were not presented, and there was a tendency to simplify results into composite indices to rank sites, without justifying aggregation methods.Despite resource constraints, most resilience potential assessments collect quantitative data that are useful for coral reef management. However, the shortcomings identified can make indicator interpretation difficult, limiting the capacity to predict the resilience of the system and support decisions. Implementation of robust approaches drawn from indicator design and selection theory can help strengthen resilience potential assessments of coral reefs and other ecosystems, ultimately improving the prospects of conservation. [ABSTRACT FROM AUTHOR]

We report for the first time three gobioid fishes: Amblygobius semicinctus (Bennett, 1833), Istigobius diadema (Steindachner, 1876), and Yongeichthys nebulosus (Forskål, 1775) from the Gujarat coast of India. We present short descriptions with species diagnostic characters, habitat and present distributions. [ABSTRACT FROM AUTHOR]

This study examines carbonate chemistry variability from 2008 to 2021 in subtropical coastal waters adjacent to Honolulu, Hawai'i. We use surface seawater carbon dioxide partial pressure (pCO2sw) measurements obtained every three hours from two buoys located along the south shore of O'ahu near anthropogenically impacted fringing reefs. The Ala Wai buoy was located 200 m offshore of a canal draining most of Honolulu, while the Kilo Nalu buoy was 1.3 miles (2 km) to the northwest, at a similar distance from shore with fewer terrestrial inputs. We compare pCO2sw variability from diurnal to interannual time scales. A trend analysis reveals a statistically significant increase in pCO2sw of +1.84 ± 0.27 µatm per year over the 11-year period. This rate is slightly lower than the average atmospheric growth rate observed during the same timeframe. In contrast to a nearby open-ocean site, the coastal sites experience amplified shorter-term variability, while seasonal to inter-annual variability is comparable to the open ocean. Ala Wai exhibits greater ranges than Kilo Nalu in all carbonate system variables due to its proximity to the Ala Wai Canal outflow. We examine the drivers that may explain both the similarities and contrasts in carbon dynamics observed between the two locations. Drivers of aragonite saturation state (WAr), an important variable for quantifying ocean acidification, are isolated from the in-situ time-series. Interannual salinity variations both due to freshwater pulses and large-scale regional salinity changes have a larger impact on WAr than temperature changes, which mostly have an effect seasonally. A large biological contribution to WAr is suspected, and further investigated using TA/DIC ratios normalized to median salinity and their slopes. Observed ratios at the south shore sites are evaluated relative to expected ratios derived from an open-ocean reference. Results suggest that dissolution and respiration are the primary biogeochemical processes occurring at these coastal sites. This highlights the significance of carbonate dissolution in anthropogenically impacted coastal waters, which is likely buffering acidification due to anthropogenic CO2 and freshwater inputs at these sites. [ABSTRACT FROM AUTHOR]

Understanding population dynamics is a long-standing objective of ecology, but the need for progress in this area has become urgent. For coral reefs, achieving this objective is impeded by a lack of information on settlement versus post-settlement events in determining recruitment and population size. Declines in coral abundance are often inferred to be associated with reduced densities of recruits, which could arise from mechanisms occurring at larval settlement, or throughout post-settlement stages. This study uses annual measurements from 2008 to 2021 of coral cover, the density of coral settlers (S), the density of small corals (SC), and environmental conditions, to evaluate the roles of settlement versus post-settlement events in determining rates of coral recruitment and changes in coral cover at Moorea, French Polynesia. Coral cover, S, SC, and the SC:S ratio (a proxy for post-settlement success), and environmental conditions, were used in generalized additive models (GAMs) to show that: (a) coral cover was more strongly related to SC and SC:S than S, and (b) SC:S was highest when preceded by cool seawater, low concentrations of Chlorophyll a, and low flow speeds, and S showed evidence of declining with elevated temperature. Together, these results suggest that changes in coral cover in Moorea are more strongly influenced by post-settlement events than settlement. The key to understanding coral community resilience may lie in elucidating the factors attenuating the bottleneck between settlers and small corals. [ABSTRACT FROM AUTHOR]

A small suite of seafloor sediment samples (water depth < 20 m) was collected in 2005 from the sheltered, logarithmic-spiral Guayaguayare Bay along the SE coast of Trinidad, West Indies. The easternmost shielded part of the bay was then occupied by a meadow of the seagrass Halodule wrightii, the closest seagrass bed to the Boca Grande, the main distributary of the Orinoco Delta. Four foraminiferal taphofacies were distinguished, ascribable to a relict coral reef system: (1) A shallow-water (~5 m) taphofacies dominated by Pararotalia sarmientoi. (2) A back-reef taphofacies (~5 m) with abundant Discorbis rosea, apparently associated with the H. wrightii. (3) A fore-reef taphofacies (water depth ~ 20 m) co-dominated by Amphistegina gibbosa and Quinqueloculina bicostata. (4) A reef-flat (~5 m) taphofacies dominated by Q. bicostata. A ternary plot of specimen wall types (agglutinated, porcellaneous, calcareous hyaline) clearly distinguished Taphofacies 1 from Taphofacies 4, porcellaneous specimens being rare in the former. A similar plot of staining + test abrasion for A. gibbosa indicated that those on Taphofacies 3, assumed to be in situ, were more heavily stained than those elsewhere and were larger. Tiny but pristine, presumably allochthonous A. gibbosa were recovered from Taphofacies 1. Two formae of Asterigerina carinata, both widely illustrated in the literature, are distinguished for the first time and named A. carinata forma conica and A. carinata forma discoida. The bay is currently filled with turbid water. The coral reef system, postdating the early Holocene transgression, would have required clear water, perhaps when the Orinoco Delta had not prograded sufficiently to impact the bay greatly. The known best depth range for the growth of amphisteginids, which are symbiotic with algae, coupled with known Holocene sea level curves for the SE Caribbean, suggest an age of ~4000 YBP. Sedimentation in the protected bay has since the development of the reef been limited. [ABSTRACT FROM AUTHOR]

Corals are habitat-forming organisms on tropical and sub-tropical reefs, often displaying diverse phenotypic behaviors that challenge field-based monitoring and assessment efforts. Symbiont chlorophyll (Chl) is a long-recognized indicator of intra- and inter-specific variation in coral's response to environmental variability and stress, but the quantitative Chl assessment of corals at the reef scale continues to prove challenging. We integrated field, airborne, and laboratory techniques to test and apply the use of reflectance spectroscopy for in situ and reef-scale estimation of Chl a and Chl c2 concentrations in a shallow reef environment of Kāne'ohe Bay, O'ahu. High-fidelity spectral signatures (420–660 nm) derived from field and airborne spectroscopy quantified Chl a and Chl c2 concentrations with demonstrable precision and accuracy. Airborne imaging spectroscopy revealed a 10-fold range of Chl concentrations across the reef ecosystem. We discovered a differential pattern of Chl a and Chl c2 use in symbiont algae in coexisting corals indicative of a physiological response to decreasing light levels with increasing water depth. The depth-dependent ratio of Chl c2:a indicated the presence of two distinct light-driven habitats spanning just 5 m of water depth range. Our findings provide a pathway for further study of coral pigment responses to environmental conditions using field and high-resolution airborne imaging spectroscopy. [ABSTRACT FROM AUTHOR]

This study aims to examine the dynamics of socio-ecological resilience of coral reef in Kotania Bay, Indonesia using a spatial-dynamic approach. The results showed that Kotania Bay coral reef in 2023 had 4 resilience classes, including very low, low, medium, and high. In addition, the highest resilience index value was 0.74, while the lowest was 0.11. Projections for 2028 predicted a reduction to 3 classes, including very low (47.37%), low (42.11%), and medium (10.53%). A further reduction to 2 classes, namely very low (73.68%) and low (26.32%), was also projected to occur by 2032. In 2038, the coral reef socio-ecological resilience was anticipated to decrease to the very low (100%) category, while a total loss was expected by 2043. The results showed that a resilience index value of 0.4 could be used as an indicator of the presence of coral-living biota and surrounding biota in good condition but vulnerable to environmental social pressures. Meanwhile, a value of less than 0.4 showed a decrease in the recovery ability despite the reduction in environmental pressure. [ABSTRACT FROM AUTHOR]

Parrotfishes (family Scaridae) are important to coral reef ecosystems and highly prized by both commercial and recreational fishers in the Hawaiian Islands. Although parrotfishes are known to be strictly diurnal, our knowledge of their habitat use and movement patterns across daily timescales in tropical systems is still somewhat limited. Here, acoustic telemetry was used to determine parrotfish habitat use and movements within a coral reef seascape at Puakō, Hawai‘i. An array of acoustic receivers was deployed in a nearshore reef to track fine-scale movements of two common species: ember parrotfish (Scarus rubroviolaceus) and palenose parrotfish (Scarus psittacus). Transmitters were mounted externally on fish and tracked over a four-week period using an acoustic positioning system. Coral habitats (reef flat, fore reef) within the study area were mapped and used in conjunction with triangulated positions to characterize habitat use and movements. Findings indicated that both species commonly inhabited the fore reef habitat during the day (91.6% and 95.0% of total detections, respectively), spending limited time in the reef flat during the day and no time in this habitat at night. Activity spaces (based on 95% and 50% kernel utilization distributions) indicated that home ranges and core use of both species were significantly larger during the day than night, with daytime home ranges (mean ±1 SD) significantly greater for ember parrotfish (8,712 ± 1,991 m2) than palenose parrotfish (3,725 ± 1,254 m2). Hourly mean detections peaked during crepuscular periods for palenose parrotfish and to a lesser extent for ember parrotfish, which was linked to movements between shallower daytime (foraging) and nighttime (resting) areas. Kernel utilization distributions indicated that both species occupied similar core use areas of the seascape (overlap index > 0.5), with both intra- and interspecific overlapping distributions present. Finding from this study highlight the value of the fore reef habitat for both daytime foraging and nocturnal resting activities of ember parrotfish and palenose parrotfish. This study also affords valuable information on primary activity spaces of both species as well as overlap between these two common congeners, which is essential for developing management strategies to conserve parrotfish populations.

Oxygen declination in coastal oceans has accelerated drastically in recent decades, both in terms of severity and spatial extent, and such disappearance of oxygen leads to dead zones where life can't survive. This phenomenon is mainly attributed to nutrient pollution and climate change due to intensified anthropogenic activities. The annual statistical oxygen mean concentrations showed the current deoxygenation trends based on (WOA_2001–2018) data comparison of 200 m below the surface water from the first two decades of the 21st century. A relatively similar significant oxygen loss of 0.5–3 ml/L was indicated in the first decade (2001–2009) over the water of continental shelves (200 m) in the tropical oceans and the areas of subtropical Pacific, Atlantic, and southern Indian oceans gradually started to fall from their moderate oxygen concentrations 4–5 ml/L between 2005 and 2009. Consequently, in the next decade (2013–2018), the negative oxygen trend persisted at a similar depth in the global oceans, and its expansion to more regions suggested that this trend of oxygen loss will continue in the future. This is a serious threat that has to be made more widely known since declines in oxygen levels in coastal oceans could have a wide range of negative impact on marine life, biogeochemical cycles, coastal habitats, economies that run on the sea, and ultimately humans. Therefore, it is crucial to investigate and put into practice management alternatives in order to lessen the effects of continuous deoxygenation on marine life and the supply of services by marine ecosystems.

Abstract The health of coral reef benthic and fish communities is implicitly connected, yet typically studied and managed separately. By developing a coupled reef population model that connects coral populations and reef fish biomass through the habitat complexity that corals build and fish live among, we aim to address this gap by holistically quantifying ecological feedbacks and responses to ecological stressors. We explored the impacts of fishing effort in conjunction with three types of ecological disturbances as they propagated through a coral reef ecosystem: (1) a disturbance that disproportionately affected small, bio‐energetically vulnerable colonies, (2) a disturbance that predominantly affected large, mechanically vulnerable colonies, and (3) a disturbance that affected colonies of all sizes randomly. We found that joint coral and fish population recovery was fastest and most complete under events affecting small colonies, followed by recovery from disturbances affecting random sizes, and lastly large‐colony disturbances. These results suggest that the retention versus loss of large coral colonies with high reproductive potential critically influenced population recovery. Low fishing levels maintained fish and coral populations and allowed for recovery after disturbances, whereas high fishing levels prevented recovery due to greater fish‐dependent coral mortality. Finally, we tested various formulations of the relationship between coral size and habitat complexity (i.e., exponential, linear, logarithmic) that constrain fish carrying capacity. All formulations led to similar population projections in most disturbance scenarios, but there were exceptions where the timing and trajectory of recovery differed, such as faster and greater recovery potential when complexity is logarithmic with respect to coral size. These findings suggest that fishing and habitat complexity mediate the recovery of coral reef populations, emphasizing the importance of describing linkages between coral size distribution and reef habitat structure. Furthermore, our results highlight the utility of the coupled‐model framework for understanding and managing the impact of disturbances at ecosystem scales.

Here we report the discovery of a single specimen of the eurysquillid mantis shrimp, Manningia andamanensis Ghosh, 1975, from Okinawa Island, southwestern Japan. This specimen is the first member of the superfamily Eurysquilloidea to be recorded from Japanese waters, and is the second record ever for this species. This new record significantly extends the range of M. andamanensis from the North Andaman Islands northeastward to Japan. Live coloration for this species is revealed in detail for the first time.

Metaprotella sandalensis Mayer, 1898 (Caprellidae: Amphipoda: Crustacea) and related congeners are widely distributed in the Indo-West Pacific. As a first step in elucidating the species diversity of Metaprotella from the Great Barrier Reef, a new species, Metaprotella lowryi sp. nov. collected from One Tree Island in southern Great Barrier Reef is described and figured. Metaprotella lowryi sp. nov. differs from M. sandalensis [sensu stricto] by shorter antenna 1 relative to body length and shorter antenna 1 peduncle article 3. The new species of Metaprotella is also closely related to M. solitaria Takeuchi & Lowry, 2017, reported from the Solitary Islands off the northern coast of New South Wales, but differs by the characters of the head, the propodus of gnathopod 2 and the dorsodistal projections of pereonite 3.

This editorial discusses the increasing problem of ocean deoxygenation in tropical ecosystems. While previous research has focused on temperate or estuarine habitats, there is growing evidence that deoxygenation is also affecting tropical habitats like coral reefs, seagrass habitats, and mangroves. The article emphasizes the need to understand the specific causes and consequences of deoxygenation in these ecosystems in order to effectively manage and mitigate its impacts. The research includes laboratory studies on how tropical marine organisms respond to deoxygenation, as well as a field study on oxygen levels in a coral reef ecosystem. The article "A 2021 Horizon Scan of Emerging Global Biological Conservation Issues" provides an overview of current and emerging challenges in biological conservation. It covers topics such as the impact of climate change on biodiversity, the spread of invasive species, and the importance of interdisciplinary collaboration and traditional knowledge in conservation efforts. [Extracted from the article]

Globally, coral reef ecosystems are undergoing significant change related to climate change and anthropogenic activities. Yet, the Cuban archipelago of Jardines de la Reina (JR) has experienced fewer stressors due to its geographical remoteness and high level of conservation. This study examines the surface and benthic reef water microbial communities associated with 32 reef sites along the JR archipelago and explores the relationship between the community composition of reef microorganisms examined using bacterial and archaeal small subunit ribosomal RNA gene (16S rRNA gene) sequencing compared to geographic, conservation/protection level, environmental, physicochemical, and reef benthic and pelagic community features. Reef nutrient concentrations were low and microbial communities dominated by picocyanobacteria and SAR11 and SAR86 clade bacteria, characteristic of an oligotrophic system. Reef water microbial community alpha and beta diversity both varied throughout the archipelago and were strongly related to geography. Three sites in the western archipelago showed unique microbial communities, which may be related to the hydrogeography and influences of the channels linking the Ana Maria gulf with the Caribbean Sea. Overall, this work provides the first extensive description of the reef microbial ecology of the Caribbean’s ‘Crown Jewel’ reef system and a framework to evaluate the influence of ongoing stressors on the reef microorganisms.

The global proliferation of natural predators, including Terpios hoshinota sponge and crown-of-thorns starfish, poses a significant threat to the ecological vitality of coral reefs. However, coral reef research currently lacks comprehensive quantitative studies on the ramifications of predator outbreaks in various coral reef landform types. To bridge this knowledge gap, this study utilized a dataset comprising 26 Sentinel-2 remote sensing images spanning the years 2016 to 2022, both pre- and post-two distinct episodes of natural predator outbreaks involving the Terpios hoshinota sponge and crown-of-thorns starfish, within the vicinity of Taiping Island. High-resolution GF-2 (PMS) remote-sensing images and satellite data were used to augment the analysis. Based on data obtained from the Google Earth platform of the Geographic Information System for remote sensing imagery, we conducted an experiment involving the classification of coral reef landform types in Taiping Island in the South China Sea. During the Support Vector Machine (SVM) classification experiments, we performed a meticulous examination of the image interpretation outcomes, making comparisons and rectifications in consultation with domain experts. Classification was performed by analyzing remote sensing images, and the identified landform types included areas characterized by dense coral sedimentation, sparse coral sedimentation, coral clusters, sand flats, and shallow reef front slopes. Subsequent analyses focused on discerning distinctive characteristics and tracing their evolutionary patterns. The findings reveal that (1) this study effectively integrates expert interpretation knowledge and an SVM classification algorithm to classify the various landform types present in Taiping Island's coral reef ecosystem. Remarkably, the classification achieved an unprecedented level of accuracy, with an overall accuracy rate of 96.46% and a kappa coefficient of 0.94. (2) The analysis showed that during the two natural predator outbreaks, the coral reef landforms on Taiping Island, which included dense coral reef areas, dense coral sedimentation areas, and sparse coral sedimentation areas, displayed significant decreases in their respective areas. The outbreak of Terpios hoshinota sponge had the most profound impact on the dense coral sedimentation area, resulting in a 72.92% decrease in the total area. Meanwhile, the outbreak of crown-of-thorns starfish had the most significant effect on the coral cluster area, causing a 59.17% reduction in total area. (3) Over the period spanning from 2016 to 2022, the degradation rate of the coral reefs on Taiping Island exceeded the recovery rate. Notably, the highest degradation rate (23.88%) occurred between March-June 2017. Conversely, the highest rate of recovery (18.03%) was observed from June-September 2017. We analyzed the dynamic characteristics of coral reef landform types, including changes in type distribution, areal extent, degradation rate, and recovery rate. Furthermore, we assessed the influence of natural disturbances on the degradation of coral reef ecosystems, thereby providing valuable insights for conservation and scientific inquiries pertaining to coral reef ecological resources in the waters surrounding Taiping Island. This effort is underpinned by a solid theoretical foundation. The Chinese and English literature cited in this article have contributed significantly to various facets, including coral reef monitoring methodologies, construction of coral reef classification systems, and assessment of coral reef ecosystem health.

The Foram Index (FI) is used to evaluate the ecological health of coral reef areas based on the content of benthic foraminifer functional groups (symbiont-bearing, opportunistic, heterotrophic) in the sediments of coral reef areas. Thus far, the application of the FI in China remains limited. In this study, an LYJ2 sediment core, 287 cm in length, which is estimated to represent approximately 2,665 years before present (a BP), was obtained from the lagoon of the Lingyang Reef on the Xisha Islands. Samples were taken at intervals of 0.5 cm to identify the foraminifera under a microscope, and the FI values were calculated. The key results are as follows. 1) the FI in the last 2,600 years ranges from 4.1 to 7.9, mean value of 5.9. 2) FI values show a fluctuating pattern, which can be divided into three periods of increased abundance: 2,380‒1,628, 1212‒572, and 252‒92 a BP; three periods of rapid decline: 1,628‒1,212, 572‒252, and 92 a BP; and one period of moderate decline: 2,665‒2,380 a BP. 3) FI exhibits interdecadal fluctuations at different scales, with cycle of 66.7 and 54.4 a . Based on the relationship between the FI values and the health status of coral reefs, we speculate that the ecological environment of the Xisha Lingyang Reef has been generally healthy for the past 2,600 years. Based on a comparative analysis of the FI and sea surface temperature, it appears that FI is mainly affected by sea surface temperature, which , in turn, is related to climate change. A high FI roughly corresponds to the Medieval Warm Period and Roman Warm Period, and a low FI roughly corresponds to the Little Ice Age (LIA) and Dark Age Cold Period (DACP). The FI values exhibit three stages of rapid decline. The first two (1,628‒1,404 and 572‒252 a BP) correspond to LIA and DACP, respectively, which may be due to the increase in atmospheric dust, rainfall, and nutrients in the waters of Lingyang Reef caused by the enhancement of the winter monsoon in the cold period. The later period (92 a BP to date) corresponds to the rapid degradation of coral reef ecosystems in the Xisha Islands in recent decades, possibly due to increased nutrient concentrations in the Antelope Reef Sea area caused by increased human activity and atmospheric nitrogen deposition fluxes. Studies have shown that FI can generally record the health status of coral reefs in the South China Sea and can be used to evaluate the health status of coral reefs in geological history.

The world's coral reefs are under threat from human activities through pollution and habitat changes. This condition is influenced by several factors, such as human activities and natural phenomena. Many efforts have been made by humans to overcome or repair coral reef ecosystems that have been damaged. One of the efforts made is to carry out coral transplants. The main goal of coral transplantation is to improve the quality of coral reefs such as increasing live coral cover, biodiversity and uniqueness of coral topography. The stages of the method carried out in the research include mapping the bottom of the waters (sounding); mapping conditions of water cover; transplantation process and monitoring. This study used the spider skeleton method for the transplant media. The results showed that the percentage of live coral cover ranged from 10% - 25% and it was found that rubble cover dominated up to >70%. During the monitoring process, it was found that algae dominated almost all of the transplant media. The high nutrients and the lack of algae-eating fish resulted in a high algae cover found on the surface of the structure and had an impact on the death of the transplanted corals. Efforts are being made to regularly clean algae to increase the survival rate and replant dead coral

This study aims to determine the abundance of fish in the recovery location of the coral reef ecosystem in Botutonuo waters, Gorontalo Province. The research was conducted in February - May 2023. The research location consisted of 2 sites, namely site A which had coral transplants with spider coral skeletons and site B which had no transplants (natural coral reefs). Observations were made 3 times with an interval of 2 weeks. Reef fish data was collected using the Underwater Visual Census (UVC) method, with a 50 m x 5 m line transect. Calculation of data using fish abundance rum. The results showed that the number of fish species found in the Botutonuo waters of Gorontalo Province at site A was 89 species with a total individual abundance of 2,429 ind/m2, while at site B there were 69 species with a total individual abundance of 2,054 ind/m2.

This study investigates the shoreline dynamics of a Caribbean reef-lined beach by utilizing a long-term satellite dataset spanning 75 years and a short-term, high-frequency dataset captured by a fixed camera over 3 years. An array of statistical methods, including ARIMA models, are employed to examine the impact of storms and potential cyclical influences on the shoreline dynamics. The findings indicate that significant storm events trigger a substantial retreat of the vegetation limit, followed by a slow recovery. Given the current frequency of such major events, complete recovery may take several decades, resulting in a minor influence of cyclones on the long-term erosion trend, which remains moderate. The short-term shoreline evolution is primarily driven by the annual cyclicity of the still water level, which generates an annual oscillation—an insight not previously reported. In the context of climate change, alterations to sea-level rise and cyclone frequency could disrupt the observed dynamic equilibrium at different timescales. Such changes could result in an alteration of existing cyclicities, disturbance of recovery periods, increased long-term shoreline retreat rates, and potentially affect overall coastal resilience over time.

Abstract Background Ocean warming is a leading cause of increasing episodes of coral bleaching, the dissociation between coral hosts and their dinoflagellate algal symbionts in the family Symbiodiniaceae. While the diversity and flexibility of Symbiodiniaceae is presumably responsible for variations in coral response to physical stressors such as elevated temperature, there is little data directly comparing physiological performance that accounts for symbiont identity associated with the same coral host species. Here, using Pocillopora damicornis harboring genotypically distinct Symbiodiniaceae strains, we examined the physiological responses of the coral holobiont and the dynamics of symbiont community change under thermal stress in a laboratory-controlled experiment. Results We found that P. damicornis dominated with symbionts of metahaplotype D1-D4-D6 in the genus Durusdinium (i.e., PdD holobiont) was more robust to thermal stress than its counterpart with symbionts of metahaplotype C42-C1-C1b-C1c in the genus Cladocopium (i.e., PdC holobiont). Under ambient temperature, however, the thermally sensitive Cladocopium spp. exhibited higher photosynthetic efficiency and translocated more fixed carbon to the host, likely facilitating faster coral growth and calcification. Moreover, we observed a thermally induced increase in Durusdinium proportion in the PdC holobiont; however, this “symbiont shuffling” in the background was overwhelmed by the overall Cladocopium dominance, which coincided with faster coral bleaching and reduced calcification. Conclusions These findings support that lineage-specific symbiont dominance is a driver of distinct coral responses to thermal stress. In addition, we found that “symbiont shuffling” may begin with stress-forced, subtle changes in the rare biosphere to eventually trade off growth for increased resilience. Furthermore, the flexibility in corals’ association with thermally tolerant symbiont lineages to adapt or acclimatize to future warming oceans should be viewed with conservative optimism as the current rate of environmental changes may outpace the evolutionary capabilities of corals. Video Abstract

Predicted future increases in both local and global stressors are expected to lead to elevated turbidity levels and an expansion of the geographical range of turbid coral reefs. Corals typically respond to elevated turbidity by increasing their rates of heterotrophy as means of compensating for low energy levels from reduced light and photosynthesis. We analysed Acropora tenuis energy acquisition along a natural turbidity gradient over two time points in Exmouth Gulf, Western Australia, using in-situ environmental data with coral physiology attributes and stable isotopes to assess trophic strategy. Our hypothesis was that as turbidity levels increased, so too would heterotrophy rates. Both δ13C and δ15N values decreased from the clear-water to the turbid sites, which along with Bayesian analysis revealed that all A. tenuis communities along the turbidity gradient are on a mixotrophic-heterotrophic feeding strategy scale. We propose that the low δ15N levels at the most turbid site may result from a combination of Acropora physiological limitations (e.g., reduced feeding capacity) and highly variable turbidity levels. In contrast, the higher δ15N at the clear-water site likely results from increased nutrient availability from additional sources such as upwelling. Our findings suggest that increased heterotrophy by coral hosts in turbid coral reef areas is not a universal pattern. Importantly, the loss of carbon in the turbid sites is not supplemented by nitrogen intake, which might suggest that Exmouth Gulfs Acropora communities are more vulnerable to future climate stressors and bleaching.

IntroductionCoral reefs as key ecosystems in Zanzibar are exposed to several anthropogenic and natural stressors.MethodsThe benthic composition and coverage of coral reefs were investigated on three data sets involving ten coral reefs monitored from 1992 to 2016. Firstly, we investigated differences in the reef composition using data from seven reefs in 2015. Secondly, we analyzed communities on three distinctive reefs (2010 to 2012) to understand the importance of seasons and reef zones (slope, crest and flat) on species abundance. Finally, we investigated long-term changes (1992 to 2016) of five reefs.ResultsBranching Porites and Acropora, and soft coral order Corallimorpharia, characterized sheltered reef communities. Soft corals and algal species characterized the reef communities exposed to strong hydrodynamic conditions, which also displayed greater cover of rocks and rubbles. The average dissimilarity between reefs ranged between 60% and 75%. The seasonal changes in community structure for reefs near Stone Town were mostly associated with soft coral Corallimorpharia. Indeed, the bare rock and algae distinguished the northern exposed reef from more sheltered reefs. Acropora was a key genus for the sheltered Chumbe reef, which explained between 14% and 18% of the dissimilarities among the three reefs. Hard corals covered between 40% and 70% in most years, with severe declines following El Niño events in 1998 and 2016. The dominating genus Acropora showed a strong decline from the late 1990s’ with signs of recovery at remote reefs compared to reefs closer to human residence.DiscussionOur results highlight the importance of seasonality and spatial differences, reflecting differences in human impact and physical exposure and significant long-term changes in coral communities. Continued monitoring of reef health is essential to evaluate the success of ongoing management to sustain the reef services.

Seaweeds are a valuable component of marine biodiversity that play multiple essential roles in Indonesia's coastal ecology and economy. This systematic review (1993–2023) aimed to provide an updated overview of seaweed distribution, biodiversity, cultivation, and industry in Indonesia. The literature search derived from major databases, Scopus, Web of Science (WoS) and ResearchGate (RG), and Google Scholar (GS) retrieved 794 studies, after removing 80 duplicates, identified 646 studies passed title and abstract screening that satisfied all criteria: Indonesia, seaweed, seaweed biodiversity and composition, which consisted of 80 exclusion studies. Full text screening decided 194 studies were selected based on the specific inclusion criteria (at least two criteria passed: seaweed distribution site, species, cultivation, and habitat). After additional filtering, 137 studies were included for extraction and analysis. We found that Indonesia is rich in seaweed biodiversity, with at least 325 identified species consisting of 103 Chlorophyceae (green algae), 167 Rhodophyceae (red algae), and 55 Phaeophyceae (brown algae), respectively. Seaweed distribution and abundance in Indonesia are influenced by environmental factors, including nutrients, grazing, competition, physical tolerance, light intensity, and degree of water circulation. Seaweed species are predominantly found in mangrove forests and coral reefs on the islands of Sumatra, Java, Kalimantan, and Sulawesi. This review provides an up-to-date and comprehensive overview of the distribution and biodiversity of seaweeds in Indonesia, highlighting the ecological, economic, and cultivation of marine resources. In addition, we identify knowledge gaps and areas for further research, which can inform sustainable seaweed management and utilization in Indonesia. This review also emphasizes the significance of this marine resource to Indonesia's environment and economy.