Search

The distributions of anthozoan corals are undercharacterized due to their wide bathymetric ranges, occurrences in remote locales, and difficulties of identification from morphology alone. Environmental DNA (eDNA) sequencing promises to be a noninvasive strategy to complement conventional approaches for mapping and monitoring the distribution and biodiversity of coral communities. Primers for eDNA metabarcoding have been designed to amplify nuclear and mitochondrial DNA barcodes in shallow scleractinians and mitochondrial MutS in deep-sea octocorals. However, a comprehensive method for eDNA metabarcoding of all anthozoan corals, including black corals, has not been developed. We leveraged a sequence database of global coral collections, from shallow water to the deep sea, to design new PCR primers for coral eDNA sequencing that target the 28S rRNA gene ( 28S rDNA ). We tested the performance of these primers by amplifying and sequencing eDNA from water samples collected in the Gulf of Mexico near mesophotic and deep-sea corals that were also imaged, sampled, and sequenced. Sequencing libraries produced using the primers were highly enriched in eDNA from octocorals, black corals and scleractinians, with up to 99.9% of the reads originating from these corals. Further, the 28S barcode amplified using the primers distinguished coral genera and species in many cases, like previously developed methods that target eDNA in only octocorals or scleractinians. We recovered amplicon sequencing variants (ASVs) identical to DNA barcodes derived from Sanger sequencing and genome skimming of corals sampled at the same field sites. This new eDNA metabarcoding strategy permits targeted eDNA sequencing of black corals, octocorals, and scleractinians at sites where they co-occur and expands our current toolkit for mapping and monitoring coral communities in shallow coral reefs and the deep sea., Competing Interests: The authors declare that they have no competing interests., (© 2024 McCartin et al.)

Coral reefs are the epitome of species diversity, yet the number of described scleractinian coral species, the framework-builders of coral reefs, remains moderate by comparison. DNA sequencing studies are rapidly challenging this notion by exposing a wealth of undescribed diversity, but the evolutionary and ecological significance of this diversity remains largely unclear. Here, we present an annotated genome for one of the most ubiquitous corals in the Indo-Pacific (Pachyseris speciosa) and uncover, through a comprehensive genomic and phenotypic assessment, that it comprises morphologically indistinguishable but ecologically divergent lineages. Demographic modeling based on whole-genome resequencing indicated that morphological crypsis (across micro- and macromorphological traits) was due to ancient morphological stasis rather than recent divergence. Although the lineages occur sympatrically across shallow and mesophotic habitats, extensive genotyping using a rapid molecular assay revealed differentiation of their ecological distributions. Leveraging "common garden" conditions facilitated by the overlapping distributions, we assessed physiological and quantitative skeletal traits and demonstrated concurrent phenotypic differentiation. Lastly, spawning observations of genotyped colonies highlighted the potential role of temporal reproductive isolation in the limited admixture, with consistent genomic signatures in genes related to morphogenesis and reproduction. Overall, our findings demonstrate the presence of ecologically and phenotypically divergent coral species without substantial morphological differentiation and provide new leads into the potential mechanisms facilitating such divergence. More broadly, they indicate that our current taxonomic framework for reef-building corals may be scratching the surface of the ecologically relevant diversity on coral reefs, consequently limiting our ability to protect or restore this diversity effectively., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Coral reefs are increasingly threatened by thermal bleaching and tropical storm events associated with rising sea surface temperatures. Deeper habitats offer some protection from these impacts and may safeguard reef-coral biodiversity, but their faunas are largely undescribed for the Indo-Pacific. Here, we show high species richness of scleractinian corals in mesophotic habitats (30-125 m) for the northern Great Barrier Reef region that greatly exceeds previous records for mesophotic habitats globally. Overall, 45% of shallow-reef species (less than or equal to 30 m), 78% of genera, and all families extended below 30 m depth, with 13% of species, 41% of genera, and 78% of families extending below 45 m. Maximum depth of occurrence showed a weak relationship to phylogeny, but a strong correlation with maximum latitudinal extent. Species recorded in the mesophotic had a significantly greater than expected probability of also occurring in shaded microhabitats and at higher latitudes, consistent with light as a common limiting factor. The findings suggest an important role for deeper habitats, particularly depths 30-45 m, in preserving evolutionary lineages of Indo-Pacific corals. Deeper reef areas are clearly more diverse than previously acknowledged and therefore deserve full consideration in our efforts to protect the world's coral reef biodiversity.

Large-scale environmental disturbances may impact both partners in coral host-Symbiodinium systems. Elucidation of the assembly patterns in such complex and interdependent communities may enable better prediction of environmental impacts across coral reef ecosystems. In this study, we investigated how the community composition and diversity of dinoflagellate symbionts in the genus Symbiodinium were distributed among 12 host species from six taxonomic orders (Actinaria, Alcyonacea, Miliolida, Porifera, Rhizostoma, Scleractinia) and in the reef water and sediments at Lizard Island, Great Barrier Reef before the 3rd Global Coral Bleaching Event. 454 pyrosequencing of the ITS2 region of Symbiodinium yielded 83 operational taxonomic units (OTUs) at a 97% similarity cut-off. Approximately half of the Symbiodinium OTUs from reef water or sediments were also present in symbio. OTUs belonged to six clades (A-D, F-G), but community structure was uneven. The two most abundant OTUs (100% matches to types C1 and A3) comprised 91% of reads and OTU C1 was shared by all species. However, sequence-based analysis of these dominant OTUs revealed host species specificity, suggesting that genetic similarity cut-offs of Symbiodinium ITS2 data sets need careful evaluation. Of the less abundant OTUs, roughly half occurred at only one site or in one species and the background Symbiodinium communities were distinct between individual samples. We conclude that sampling multiple host taxa with differing life history traits will be critical to fully understand the symbiont diversity of a given system and to predict coral ecosystem responses to environmental change and disturbance considering the differential stress response of the taxa within., (© 2018 Phycological Society of America.)

The Coral Triangle (CT) region of the Indo-Pacific realm harbors an extraordinary number of species, with richness decreasing away from this biodiversity hotspot. Despite multiple competing hypotheses, the dynamics underlying this regional diversity pattern remain poorly understood. Here, we use a time-calibrated evolutionary tree of living reef coral species, their current geographic ranges, and model-based estimates of regional rates of speciation, extinction, and geographic range shifts to show that origination rates within the CT are lower than in surrounding regions, a result inconsistent with the long-standing center of origin hypothesis. Furthermore, endemism of coral species in the CT is low, and the CT endemics are older than relatives found outside this region. Overall, our model results suggest that the high diversity of reef corals in the CT is largely due to range expansions into this region of species that evolved elsewhere. These findings strongly support the notion that geographic range shifts play a critical role in generating species diversity gradients. They also show that preserving the processes that gave rise to the striking diversity of corals in the CT requires protecting not just reefs within the hotspot, but also those in the surrounding areas., (© 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.)

Models of the future of coral reefs are potentially sensitive to theoretical assumptions, variable selectivity, interactions, and scales. A number of these aspects were evaluated using boosted regression tree models of numbers of coral taxa trained on ~1000 field surveys and 35 spatially complete influential environmental proxies at moderate scales (~6.25 km2). Models explored influences of climate change, water quality, direct human‐resource extraction, and variable selection processes. We examined the predictions for numbers of coral taxa using all variables and compared them to models based on variables commonly used to predict climate change and human influences (eight and nine variables). Results indicated individual temperature variables alone had lower predictive ability (R2 < 2%–7%) compared to human influence variables (6%–18%) but overall climate had a higher training–testing fit (70%) than the human influence (63%) model. The full variable model had the highest fit to the full data (27 variables; R2 = 85%) and indicated the strongly interactive and complex role of environmental and human influence variables when making moderate‐scale biodiversity predictions. Projecting changes using Coupled Model Intercomparison Project (CMIP) 2050 Representative Concentration Pathways (RCP2.6 and 8.5) water temperature predictions indicated high local variability and fewer negative effects than predictions made by coarse scale threshold and niche models. The persistence of coral reefs over periods of rapid climate change is likely to be caused by smaller scale variability that is poorly simulated with coarse scale modeled predictions. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Asociación Geológica Argentina is the property of Asociacion Geologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The ecological and evolutionary consequences of partner fidelity and flexibility among coral–dinoflagellate mutualisms are widely debated. Resident symbionts can modulate the resilience of their hosts to environmental stressors, which explains, in part, why host–symbiont combinations differ over broad geographic ranges and across physical–environmental gradients in light and temperature. Therefore, flexibility in these mutualisms may influence the longevity of coral populations and communities subjected to ocean warming. However, despite decades of research, basic knowledge about these mutualisms remains incomplete, hindering the development of predictive ecological theory. In particular, few studies have investigated the long-term composition of symbiont populations within individual colonies. To further examine the extent to which coral colonies have stable relationships with specific symbionts over multiple years, diverse coral taxa (Scleractinia) from a West Indo-Pacific fore reef (Palau) were tagged and sampled at various intervals—ranging from six months to several years—over nine years' time. Symbiont identity was examined using multiple genetic markers that resolved symbiont diversity to species and individual genotypes (i.e., clonal strains). Members of the genus Cladocopium (formerly Symbiodinium Clade C) were prevalent across the host community. Generally, corals with open modes of symbiont acquisition harbored a host–generalist symbiont, while corals with vertical symbiont transmission were associated with co-evolved host-specific symbionts. Consistent with previous colony monitoring studies, symbiont populations in a majority of colonies were dominated by one species and one strain (based on multilocus genotyping) over multiple years. Thus, the distribution of symbiont diversity at the genus, species and clone level, comprising specific and stable partner combinations, scale predictably to reef habitat, host taxon, and individual colony. Recognizing these fundamental ecological patterns establishes a more comprehensive understanding of the population and community structure of these mutualisms. [ABSTRACT FROM AUTHOR]

Abstract Background Mesophotic coral communities are increasingly gaining attention for the unique biological diversity they host, exemplified by the numerous mesophotic fish species that continue to be discovered. In contrast, many of the photosynthetic scleractinian corals observed at mesophotic depths are assumed to be depth-generalists, with very few species characterised as mesophotic-specialists. This presumed lack of a specialised community remains largely untested, as phylogenetic studies on corals have rarely included mesophotic samples and have long suffered from resolution issues associated with traditional sequence markers. Results Here, we used reduced-representation genome sequencing to conduct a phylogenomic assessment of the two dominant mesophotic genera of plating corals in the Indo-Pacific and Western Atlantic, respectively, Leptoseris and Agaricia. While these genome-wide phylogenies broadly corroborated the morphological taxonomy, they also exposed deep divergences within the two genera and undescribed diversity across the current taxonomic species. Five of the eight focal species consisted of at least two sympatric and genetically distinct lineages, which were consistently detected across different methods. Conclusions The repeated observation of genetically divergent lineages associated with mesophotic depths highlights that there may be many more mesophotic-specialist coral species than currently acknowledged and that an urgent assessment of this largely unstudied biological diversity is warranted.

Dendrophylliidae represents one of the most speciose families of scleractinian coral, expressing a wide range of morphological and ecological traits. Recent phylogenetic analyses of the family have indicated that several conventional genera are in need of revision. In the Gulf of Thailand, dendrophylliids are predominantly found on hard-substrate reefs and pinnacles, or on soft-substrate habitats. Soft-substrate habitats in the Gulf of Thailand have been shown to host unique species assemblages and faunal ecology. Here we provided an updated phylogenetic hypothesis for the Dendrophylliidae based on newly sequenced species, and analyses integrating morphology, genetics and ecology. High-resolution Micro-CT was used to create digital versions of the studied species, allowing for non-destructive examination of internal and external features. Our findings allowed for a taxonomic assessment of the genera Heteropsammia and Tubastraea, with the species Balanophyllia (Eupsammia) stimpsonii, moved to the genus Tubastraea. They also support the polyphyly of Dendrophyllia and Cladopsammia. In-situ surveys provided population-density information for four dendrophylliid species from soft substrate habitats, indicating that the species Heteropsammia moretonensis may be the most widespread within the Gulf of Thailand. These surveys also provided novel ecological documentation associated with these corals, including protocooperative feeding upon a sea pen by Tubastraea stimpsonii comb. nov., and feeding upon other cnidarians by Heteropsammia spp. [ABSTRACT FROM AUTHOR]

Corals are under siege by both local and global threats, creating a worldwide reef crisis. Cryopreservation is an important intervention measure and a vital component of the modern coral conservation toolkit, but preservation techniques are currently limited to sensitive reproductive materials that can only be obtained a few nights per year during spawning. Here, we report the successful cryopreservation and revival of cm-scale coral fragments via mL-scale isochoric vitrification. We demonstrate coral viability at 24 h post-thaw using a calibrated oxygen-uptake respirometry technique, and further show that the method can be applied in a passive, electronics-free configuration. Finally, we detail a complete prototype coral cryopreservation pipeline, which provides a platform for essential next steps in modulating post-thaw stress and initiating long-term growth. These findings pave the way towards an approach that can be rapidly deployed around the world to secure the biological genetic diversity of our vanishing coral reefs. Cryopreservation is one approach to conserving the genetic diversity of threatened coral reefs but has thus far been limited to difficult-to-obtain coral reproductive material. Using a new cytotechnology called isochoric vitrification, this study reports the successful cryopreservation and revival of whole mature coral fragments. [ABSTRACT FROM AUTHOR]

Background: Mesophotic coral communities are increasingly gaining attention for the unique biological diversity they host, exemplified by the numerous mesophotic fish species that continue to be discovered. In contrast, many of the photosynthetic scleractinian corals observed at mesophotic depths are assumed to be depth-generalists, with very few species characterised as mesophotic-specialists. This presumed lack of a specialised community remains largely untested, as phylogenetic studies on corals have rarely included mesophotic samples and have long suffered from resolution issues associated with traditional sequence markers. Results: Here, we used reduced-representation genome sequencing to conduct a phylogenomic assessment of the two dominant mesophotic genera of plating corals in the Indo-Pacific and Western Atlantic, respectively, Leptoseris and Agaricia. While these genome-wide phylogenies broadly corroborated the morphological taxonomy, they also exposed deep divergences within the two genera and undescribed diversity across the current taxonomic species. Five of the eight focal species consisted of at least two sympatric and genetically distinct lineages, which were consistently detected across different methods. Conclusions: The repeated observation of genetically divergent lineages associated with mesophotic depths highlights that there may be many more mesophotic-specialist coral species than currently acknowledged and that an urgent assessment of this largely unstudied biological diversity is warranted. [ABSTRACT FROM AUTHOR]

The rapid origination and diversification of major animal body plans during the early Cambrian coincide with the rise of Earth's first animal‐built framework reefs. Given the importance of scleractinian coral reefs as ecological facilitators in modern oceans, we investigate the impact of archaeocyathan (Class Archaeocyatha) reefs as engineered ecosystems during the Cambrian radiation. In this study, we present the first high‐resolution, three‐dimensional (3D) reconstructions of branching archaeocyathide (Order Archaeocyathida) individuals from three localities on the Laurentian paleocontinent. Because branched forms in sponges and corals display phenotypic plasticity that preserve the characteristics of the surrounding growth environment, we compare morphological measurements from our fossil specimens to those of modern corals to infer the surface conditions of Earth's first reefs. These data demonstrate that archaeocyaths could withstand and influence the flow of water, accommodate photosymbionts, and build topographically complex and stable structures much like corals today. We also recognize a stepwise increase in the roughness of reef environments in the lower Cambrian, which would have laid a foundation for more abundant and diverse coevolving fauna. [ABSTRACT FROM AUTHOR]

Accurate identification of scleractinian coral species is fundamental for proper biodiversity estimates, for aiding in efforts of reef monitoring, conservation, restoration, and for the management of coral reefs. Here, we provide the first DNA barcoding reference library for coral species in Eilat, Red Sea, based on the mitochondrial gene cytochrome c oxidase subunit I (COI), targeting the identification of stony coral species from shallow (0–12 m) reefs. A total of 191 specimens were collected, depicting 14 families, 39 genera, and 94 species (all are new full species records to the BOLD system). Three species (Sclerophyllia margariticola, Cyphastrea magna, and Psammocora profundacella) are first records for Eilat's coral reef. The results presented here strengthen the claim that COI is not universally informative for delimitation of stony coral species, a notion reinforced by the constructed maximum likelihood phylogenetic tree. This library is the first step in a long journey towards elucidating coral biodiversity in the coral reef at Eilat and for improving future management and monitoring efforts. [ABSTRACT FROM AUTHOR]

We present a comprehensive checklist of scleractinian (hard) corals for the Mersing Islands, Malaysia based on surveys conducted at 24 reefs across protected and unprotected marine areas. A total of 261 species of corals from 16 families and one incertae sedis (Pachyseris spp.) were recorded, along with ten records that are new for the east coast of Peninsular Malaysia. Compared against the IUCN Red List, 46.7% of coral species found in the Mersing Islands were of Least Concern (LC), 29.5% as Near Threatened (NT) and 16.4% Vulnerable (V). Only one recorded species, Pectinia maxima (Moll & Best, 1984), was listed as Endangered (EN). Baseline species diversity data are essential for the monitoring and management of marine biodiversity, especially within marine protected areas. With both protected and unprotected coral reef areas in the vicinity of the widely scattered Mersing Islands, the diversity and distribution of coral species can be used as the basis for area-based conservation and management strategies. The diversity and abundance of scleractinian corals of each island or area should be surveyed periodically to ensure the appropriate level of protection is afforded to retain scleractinian biodiversity in this region. [ABSTRACT FROM AUTHOR]

Aim: Forecasting the influence of climate change on coral biodiversity and reef functioning is important for informing policy decisions. Dominance shifts, tropicalization and local extinctions are common responses of climate change, but uncertainty surrounds the reliability of predicted coral community transformations. Here, we use species distribution models (SDMs) to assess changes in suitable coral habitat and associated patterns in biodiversity across Western Australia (WA) under present‐day and future climate scenarios (RCP 2.6 and RCP 8.5). Location: Coral reef systems and communities in WA. Methods: We developed SDMs with model prediction uncertainty analyses, using specimen‐based occurrence records of 188 hermatypic scleractinian coral species and seven variables to estimate present‐day and future changes to coral species distribution and biodiversity patterns in WA under climate change conditions. Results: We found that suitable habitat is predicted to increase across all regions in WA under RCP2.62050, RCP8.52050 and RCP2.62100 scenarios with all tropical and subtropical regions remaining coral biodiversity strongholds. Under the extreme RCP8.52100 scenario, however, a clear tropicalization trend could be observed with coral species expanding their range to mid‐high latitude regions, while a substantial drop in coral species richness was predicted at low latitude tropical coral reefs, such as the inshore Kimberley and offshore NW reefs. Despite the predicted expansion south, we identified a net decline in coral biodiversity across the WA coastline. Main conclusions: Results from the models predicted higher net coral biodiversity loss at low latitude tropical regions compared with net gains at mid‐high latitude regions under RCP8.52100. These results are likely to be representative of latitudinal trends across the Southern Hemisphere and highlight that increases in habitat suitability at higher latitudes may not lead to equivalent biodiversity benefits. Urgent action is needed to limit climate change to prevent spatial erosion of tropical coral communities, extinction events and loss of tropical ecosystem services. [ABSTRACT FROM AUTHOR]

The article presents a study on the saturating effect of biodiversity on imperiled coral reefs. Topics discussed include coral benefit from biodiversity, role of intraspecific coral competition in producing biodiversity effects, and an experiment that incorporated a greater range of coral species richness to better asses the role of coral diversity.

Sri Lanka, an island nation located off the southeast coast of the Indian sub-continent, has an unappreciated diversity of corals and other reef organisms. In particular, knowledge of the status of coral reefs in its northern region has been limited due to 30 years of civil war. From March 2017 to August 2018, we carried out baseline surveys at selected sites on the northern coastline of the Jaffna Peninsula and around the four largest islands in Palk Bay. The mean percentage cover of live coral was 49 ± 7.25% along the northern coast and 27 ± 5.3% on the islands. Bleaching events and intense fishing activities have most likely resulted in the occurrence of dead corals at most sites (coral mortality index > 0.33). However, all sites were characterised by high values of diversity (H' ≥ 2.3) and evenness (E ≥ 0.8). The diversity index increased significantly with increasing coral cover on the northern coast but showed the opposite trend on the island sites. One hundred and thirteen species of scleractinian corals, representing 16 families and 39 genera, were recorded, as well as seven soft coral genera. Thirty-six of the scleractinian coral species were identified for the first time on the island of Sri Lanka. DNA barcoding using the mitochondrial cytochrome oxidase subunit I gene (COI) was employed to secure genetic confirmation of a few difficult-to-distinguish new records: Acropora aspera, Acropora digitifera, Acropora gemmifera, Montipora flabellata, and Echinopora gemmacea. [ABSTRACT FROM AUTHOR]

The Great Barrier Reef is a diverse ecosystem of outstanding universal value that is under an increasing level of cumulative threat. The status of biodiversity, particularly that of habitat-forming taxa is not known, and more data are needed to evaluate this. Here, we summarize scleractinian coral distribution records in the Lizard Island reef system from 1976 to 2020 to explore the persistence of the local species pool across 44 years. By undertaking replicated spatio-temporal biodiversity surveys (2011, 2015, 2017, 2020) at 14 sites and compiling published species records from this location (1976–2020), we determine that 368 species of hermatypic scleractinian coral have been recorded from Lizard Island and/or nearby reefs over the last 44 years. Two hundred and eighty-four of those species (77.2%) have ongoing records across this time period indicating temporal persistence at the local scale. However, 28 species (7.6%) that were reliably recorded prior to 2011 have not been recorded in subsequent years and may be at risk of local extinction. A further 31 species (8.4%) may be at risk of local range reduction as they have not been recorded at Lizard Island and/or at nearby reefs since 2015. The remaining 25 species (6.8%) were deemed taxonomically unreliable records. Fifty-three species are recorded from Lizard Island for the first time in the 2011–2020 surveys, however, further integrated taxonomic research is required to verify some of these records. At a site level, species diversity has been in a state of flux over the 2011–2020 period with significant declines in species richness notable from 2011 to 2017, and significant recovery from 2017 to 2020. Overall, this dataset indicates local extinction or local range reduction is a tangible risk for 59 species (16% of the species pool) in the Lizard Island region. Additional targeted searching for these species along with temporal monitoring of species abundance and size structure is warranted to better understand the status of coral biodiversity at this globally significant location. [ABSTRACT FROM AUTHOR]

Acropora pruinosa is a threatened zooxanthellate scleractinian coral that is distributed in the temperate areas along the coastline of Japan and the northern area of the South China Sea. Since A. pruinosa propagates both asexually and sexually, assessing clonal diversity and genetic connectivity among populations is important for conservation. In addition, high morphological variations in the field create confusion during species identification. To examine the existence of hidden genetic lineages, clonality, and genetic connectivity of A. pruinosa for conservation, we applied microsatellite analysis. Clustering analysis indicated two distinct geographically separated genetic lineages: one is distributed in the west, and the other is distributed in the east. The two lineages co-existed in Nishidomari, Kochi. There was no obvious difference in morphological characteristics between the two lineages. Although the factors influencing the observed distribution patterns remain unknown, there is a possibility that the two lineages might have diverged somewhere in the north-western Kyushu and north-eastern Pacific coast habitats in the past, and then periodically colonized the current habitats. A low clonal diversity was observed in most of the populations, indicating a high rate of asexual reproduction associated with their branching morphologies. In addition, there are strong genetic structuring in this species, indicating weak connectivity among populations. These results indicated a low larval dispersal potential among populations and that populations are basically sustained by a high rate of clone propagation and self-seeding. The existence of cryptic lineages and genetically isolated populations with high clonality emphasized the importance of conservation of A. pruinosa.

Model systems approaches search for commonality in patterns underlying biological diversity and complexity led by common evolutionary paths. The success of the approach does not rest on the species chosen but on the scalability of the model and methods used to develop the model and engage research. Fine-tuning approaches to improve coral cell cultures will provide a robust platform for studying symbiosis breakdown, the calcification mechanism and its disruption, protein interactions, micronutrient transport/exchange, and the toxicity of nanoparticles, among other key biological aspects, with the added advantage of minimizing the ethical conundrum of repeated testing on ecologically threatened organisms. The work presented here aimed to lay the foundation towards development of effective methods to sort and culture reef-building coral cells with the ultimate goal of obtaining immortal cell lines for the study of bleaching, disease and toxicity at the cellular and polyp levels. To achieve this objective, the team conducted a thorough review and tested the available methods (i.e. cell dissociation, isolation, sorting, attachment and proliferation). The most effective and reproducible techniques were combined to consolidate culture methods and generate uncontaminated coral cell cultures for ~7 days (10 days maximum). The tests were conducted on scleractinian corals Pocillopora acuta of the same genotype to harmonize results and reduce variation linked to genetic diversity. The development of cell separation and identification methods in conjunction with further investigations into coral cell-type specific metabolic requirements will allow us to tailor growth media for optimized monocultures as a tool for studying essential reef-building coral traits such as symbiosis, wound healing and calcification at multiple scales. [ABSTRACT FROM AUTHOR]

Copyright of Al-Andalus Journal for Applied Sciences is the property of Alandalus University for Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Many corals depend upon the highly specialised and intricate relationship they form with Symbiodiniaceae algal symbionts. Porites lutea is a massive reef-building coral found throughout Southeast Asia that hosts these endosymbionts obligately. Yet despite the prevalence and importance of P. lutea as one of the most dominant corals here, its associated Symbiodiniaceae communities have not been precisely characterised. In this study, we used high-throughput DNA amplicon sequencing of the nuclear internal transcribed spacer 2 (ITS2) to characterise the diversity, community structure and biogeographic distribution of Symbiodiniaceae in P. lutea throughout Singapore and Peninsular Malaysia. Consistent with previous studies, we found that Cladocopium was the most dominant genus among all samples, and Cladocopium C15 was the most dominant type (or subclade) with 100% occurrence in all samples from every study site. Results also revealed numerous Symbiodiniaceae types associated with P. lutea that were previously undetected in Southeast Asia. Endosymbiont diversity and community variation are driven by a combination of site-specific mean monthly cloud cover and variance in monthly sea surface temperature. This study contributes baseline data toward understanding differences in Symbiodiniaceae assemblages hosted by P. lutea, shedding light on how they might be indicative of particular environmental conditions and coral responses. [ABSTRACT FROM AUTHOR]

Comparative lists of species' extinction risk are increasingly being used to prioritise conservation resources. Extinction risk is most rigorously assessed using quantitative data on species' population trajectories, but in the absence of such data, assessments often rely on qualitative estimates based on expert opinion of species abundances, distributions and threats. For example, one-third of coral species are classified as threatened and another third as near threatened on the IUCN Red List, despite a lack of data at the population level for the vast majority of species. Since many taxa show a strong correlation between species traits and extinction risk, an alternate approach is to identify traits associated with extinction in other groups and apply them to the taxon of interest. Here, we examine whether life-history traits associated with stress tolerance, fecundity and habitat specialisation are correlated with Red List conservation status in reef corals. We found no relationship between conservation status and life-history traits, suggesting that either traits identified as important predictors of extinction risk in other taxa are not important in corals, or that conservation status does not accurately reflect species' relative extinction risk. Therefore, using global-scale extinction risk assessments to inform conservation of coral reefs presents a high risk of 'silent extinctions' of undescribed species. We argue that the conservation status for the vast majority of coral species should be 'data deficient' and is likely to remain so for the foreseeable future, and that the status and trends of coral populations can only be reliably assessed at relatively small scales. [ABSTRACT FROM AUTHOR]

Cumulative anthropogenic pressures have triggered a global decline in the health of marine ecosystems, and coral reefs, in particular, are in crisis. With climate and population-related pressures predicted to intensify in the coming decades, it is increasingly crucial to develop cost-effective and accurate monitoring tools to document changes to these important ecosystems. Environmental DNA (eDNA) coupled with metabarcoding is a powerful tool for surveying a wide variety of biota. Here, we develop a baseline eDNA toolkit targeting scleractinian corals and validate its performance in conjunction with data derived on traditional diver-based visual surveys at the Cocos (Keeling) Islands. Three assays targeting the ITS2 and 16S barcoding regions were designed, which broadly detected diversity within Scleractinia and Porifera. Our eDNA assays recovered 78 ITS2 operational taxonomic units (OTUs) from 25 scleractinian genera which is comparable to the level of diversity recorded on visual surveys (68 species from 26 genera). There were some notable differences in the species detected using eDNA versus visual records that may relate to either misidentifications, intragenic variation, differential assay performance or cryptic species. Our data demonstrate that a multi-assay eDNA analytical approach, applied on surface water collections, represents a powerful and complementary way to survey diversity that can also reveal fine scale spatial differentiation in community composition. With further refinement and improved reference databases, we envisage eDNA to become a powerful complement to visual surveys and to play a key role in monitoring the health and diversity of complex coral reefs ecosystems. [ABSTRACT FROM AUTHOR]

Aim: Mesophotic coral ecosystems (MCEs) are unique communities that support a high proportion of depth‐endemic species distinct from shallow‐water coral reefs. However, there is currently little consensus on the boundaries between shallow and mesophotic coral reefs and between upper versus lower MCEs because studies of these communities are often site specific. Here, we examine the ecological evidence for community breaks, defined here as species loss, in fish and benthic taxa between shallow reefs and MCEs globally. Location: Global MCEs. Time period: 1973–2017. Major taxa studied: Macrophytes, Porifera, Scleractinia, Hydrozoa, Octocorallia, Antipatharia and teleost fishes. Methods: We used random‐effects models and breakpoint analyses on presence/absence data to identify regions of higher than expected species loss along a depth gradient of 1–69 m, based on a meta‐analysis of 26 studies spanning diverse photoautotrophic and heterotrophic taxa. We then investigated the extent to which points of high faunal turnover can be explained by environmental factors, including light, temperature and nutrient availability. Results: We found evidence for a community break, indicated by a significant loss of shallow‐water taxa, at ~ 60 m across several taxonomically and functionally diverse benthic groups and geographical regions. The breakpoint in benthic composition is best explained by decreasing light, which is correlated with the optical depths between 10 and 1% of surface irradiance. A concurrent shift in the availability of nutrients, both dissolved and particulate organic matter, and a shift from photoautotroph to heterotroph‐dominated assemblages also occurs at ~ 60 m depth. Main conclusions: We found evidence for global community breaks across multiple benthic taxa at ~ 60 m depth, indicative of distinct community transitions between shallow and mesophotic coral ecosystems. Changes in the underwater light environment and the availability of trophic resources along the depth gradient are the most parsimonious explanations for the observed patterns. [ABSTRACT FROM AUTHOR]

Biodiversity associated with the Mediterranean stony coral Cladocora caespitosa (Linnaeus, 1767) was investigated at three levels: "microscale", focused on macrobenthic invertebrates within colonies; "mesoscale", focused on epibenthic megafauna among colonies; "macroscale", focused on associated ichthyofauna. The aim was to quantify associated diversity in terms of species richness, testing the efficiency of colony size (surface covered by a single colony) for the "microscale", and colony density or total coral coverage for "meso-" and "macroscale" as predictors and the consistency of models based on Species-Area Relationship (SAR) for those estimations. At level of "microscale", colony size was a good predictor, with richness of invertebrates increasing with the increasing of surface covered by each colony of C. caespitosa , following Arrhenius model. At levels of "mesoscale" and "macroscale", richness of epibenthic megafauna and fish were not related neither to colony density nor total coral coverage, but to sampled area, and frequency-based estimates of richness were used. The importance of C. caespitosa varied according to the investigation level, with most of taxa richness detected at the level of "microscale". • Cladocora caespitosa is an important habitat builder. • Quantification of its importance varied according to investigation scale, method and target. • Colony size: good predictor of associated taxa richness with Arrhenius model. • Sampled area: good predictor for fish and epibenthic megafauna richness. • Epibenthic megafauna and fish richness is no related with colony density or coverage. [ABSTRACT FROM AUTHOR]

An anomalous El Niño-associated sea surface temperature stress event was predicted to affect tropical Australian reefs, including those in North Western Australia in the summer of 2015/2016. Thermal stress events are well known to result in widespread hard coral mortality events, but other symbiotic organisms such as soft corals, giant clams and sponges can also be affected. Here, we examine whether the 2016 thermal stress event deleteriously impacted coral reef communities in the remote Bonaparte Archipelago, central inshore Kimberley bioregion, North West Australia. Our results confirm the region experienced a thermal stress event of similar magnitude to other regional localities (i.e., southern Kimberley and Scott Reef), but contrary to those locations that experienced widespread bleaching events, we find no evidence to suggest widespread mortality events occurred among photosymbiotic organisms in the Bonaparte Archipelago. Photosymbiotic organisms in this region are assumed to be well adapted to fluctuating environmental conditions; however, in this instance, a greater magnitude of night-time cooling may have driven variability in regional susceptibility to thermal stress. The Bonaparte Archipelago is emerging as a globally significant ecological refuge for photosymbiotic benthic fauna that are threatened by cumulative anthropogenic and climate stressors in other parts of their distribution. [ABSTRACT FROM AUTHOR]

Two new reef coral species, Porites farasani sp. nov. and Porites hadramauti sp. nov. (Scleractinia, Poritidae), are described from the Red Sea and the Gulf of Aden. Porites farasani sp. nov. only occurs in the Farasan Islands in the southern Red Sea, while P. hadramauti sp. nov. has been collected in the Yemen Hadramaut region in the Gulf of Aden. Both species presented striking in situ differences with respect to other Porites species, and were characterized by small encrusting colonies and unusual polyp colouration. In order to test the genetic distinctiveness of P. farasani sp. nov. and P. hadramauti sp. nov. between each other and with respect to other representatives in the genus Porites, we investigated their evolutionary relationships with eight other morphological species of Porites occurring in the Red Sea and in the Gulf of Aden. Two DNA loci, the mitochondrial putative control region and the nuclear ribosomal ITS region, were sequenced, and three species delimitation approaches based on barcoding threshold (Automated Barcoding Gap Discovery) and coalescence theory (Poisson-Tree process, Generalized Mixed Yule Coalescent) were applied. Phylogenetic and species delimitation analyses were overall concordant, resolving P. farasani sp. nov. and P. hadramauti sp. nov. as two divergent but closely related lineages. Of the other morphologically defined Porites species, three were genetically differentiated (P. rus, P. columnaris and P. fontanesii), but five were genetically indistinguishable. The discovery of two regional endemics confirms the importance of the Red Sea and the Gulf of Aden as regions of high biodiversity and suggests the need for an integration of genome-wide molecular data with the re-evaluation of skeletal structures in the systematics of Porites. [ABSTRACT FROM AUTHOR]

Abstract Scleractinian cold-water corals (CWCs), such as Lophelia pertusa and Madrepora oculata , build complex frameworks and carbonate mound habitats in the deep-sea and are regarded as deep-sea biodiversity hotspots. However, there is a paucity of research regarding temporal change in the biological composition of these CWC habitats and analysis of this change is critical, especially considering the anthropogenic influences impacting upon these vital habitats. This study is the first to analyse temporal biological change on a CWC mound at a small temporal (4 years) and large spatial (entire mound) scale. Video datasets were collected over the Piddington Mound of the Moira Mounds, Porcupine Seabight, offshore Ireland, in 2011 and 2015. 0.25 m2 quadrats were placed on 510 screenshots from each year (1020 total). Species were identified and quantified. CTD data were also analysed to investigate potential contributory causes of change. There was a highly significant (P < 0.01) decline in average M. oculata percentage cover from 2011 (1.37 ± 3.79%) to 2015 (0.70 ± 2.76%); however, there was not a significant change (P = 0.74) in average L. pertusa percentage cover in 2011 (2.33 ± 7.52%) when comparing it with 2015 (5.28 ± 7.88%). Additionally, there was an increase in average percentage cover of two poriferan species, Aphrocallistes sp. and Hexadella sp., from 2011 (1.18 ± 2.35%; 0.21 ± 0.42%, respectively) to 2015 (2.15 ± 3.48%; 0.33 ± 0.55%, respectively) (P < 0.01 for both species). Shannon-Weiner and Pielou's Species Evenness diversity indices were generally higher in 2011 than in 2015. This overall decline in diversity and increase in poriferan abundances is attributed to the decline in M. oculata , which may have been influenced by altered environmental conditions in 2015, as indicated by the CTD data. Moreover, differing biological and ecological responses of L. pertusa and M. oculata to environmental changes were considered and discussed as possible contributors to the results observed for these two species. If M. oculata percentage cover declines linearly at the current rate (approximately 0.17% per year, if a constant decline in each of the four years), then by 2019, this species may be nearly absent from the Piddington Mound, which would have major effects on species' abundances, distributions, and biodiversity. Therefore, further research and continuous monitoring of the temporal change in biological composition within CWC reef/mound habitats are critical. Highlights • 34 species and morphospecies encompassing 7 phyla were identified on a CWC mound. • Average percentage cover of Madrepora oculata declined significantly over 4 years. • Average percentage cover of two sponge species increased significantly over 4 years. • Temporal change in water temperature and salinity was found around the CWC mound. [ABSTRACT FROM AUTHOR]

To persist in oligotrophic waters, reef-building corals rely on nutritional interactions with symbiotic dinoflagellates of the family Symbiodiniaceae, but the true diversity of this family remains poorly characterised. In this paper, we assess Symbiodiniaceae richness at Atauro Island (Timor-Leste) as well as on reefs of the neighbouring Timor mainland, using direct sequencing of three gene regions: cob gene, mitochondrion; ITS2 region, nucleus; and psbAncr region, chloroplast; in addition to a highly multiplexed application of next-generation sequencing. These geographic sites are among the most biodiverse in the world, but have never had their symbiont communities studied. Despite their proximity, our results reveal symbiont richness 1.25 times higher at Atauro Island than the Timor mainland, a result evident in dominant sequences. In contrast, Timor had a significantly richer background sequence diversity. Although sampling was restricted to shallow sites only, symbiont richness at Atauro Island was also higher than comparative reefscapes globally, after standardising for number of taxa sampled. While Atauro and Timor have related symbiont populations, with the same novel types recorded at both sites, there were also clear differences in symbiont composition between the two geographic regions, with Timor displaying a consortium more characteristic of stressed reef environments (proportionally hosting twice as many Durusdinium sequences, formerly clade D, as Atauro). These results reveal a symbiont richness that matches the high biodiversity of these reefs, but also potentially negative effects of proximal human populations on Symbiodiniaceae, even when previous studies have shown corals to be largely unaffected. [ABSTRACT FROM AUTHOR]

Abstract Structure and spatial variability of coralligenous assemblages of the Apulian continental shelf in the southern Adriatic Sea were investigated. The area consists of small coralligenous outcrops distributed between 30 and 100 m of depth on coarse detritic or muddy bottom. Photographic samples, obtained through a Remotely Operated Vehicle, were analyzed to evaluate the abundance of the main taxa or morphological groups of macroalgae and sessile invertebrates, and the deposited sediment. A multifactorial sampling design was used to compare assemblages at two depth ranges, the shallow outcrops (between 35 and 45 m) and the deep outcrops (between 60 and 70 m), and to determine the main scales of spatial variation. Assemblages were dominated by encrusting and erect sponges, encrusting and filamentous algae, scleractinians, encrusting and erect bryozoans and the Zoantharia Parazoanthus axinellae. Deep assemblages were characterized by lower alpha and beta diversity, and by the decrease or disappearance of sensitive organisms, such as coralline macroalgae, scleractinians and erect bryozoans, and by the dominance of encrusting sponges, P. axinellae and hydrozoans. Sedimentation was higher on deep outcrops and was suggested to be the main driver of differences between shallow and deep assemblages. The peculiar composition of assemblages found in the Apulian continental shelf provides evidence that these outcrops represent an uncommon coralligenous habitat. Highlights • Coralligenous assemblages of the Apulian continental shelf were investigated. • Photographic samples, obtained through a Remotely Operated Vehicle, were analyzed. • Assemblages of shallow (35–45 m) and deep outcrops (60–70 m) were compared. • Sedimentation was higher on deep outcrops. • Deep assemblages were characterized by lower alpha and beta diversity. [ABSTRACT FROM AUTHOR]

Coral reefs are increasingly threatened by thermal bleaching and tropical storm events associated with rising sea surface temperatures. Deeper habitats offer some protection from these impacts and may safeguard reef-coral biodiversity, but their faunas are largely undescribed for the Indo-Pacific. Here, we show high species richness of scleractinian corals in mesophotic habitats (30-125 m) for the northern Great Barrier Reef region that greatly exceeds previous records for mesophotic habitats globally. Overall, 45% of shallow-reef species (less than or equal to 30 m), 78% of genera, and all families extended below 30 m depth, with 13% of species, 41% of genera, and 78% of families extending below 45 m. Maximum depth of occurrence showed a weak relationship to phylogeny, but a strong correlation with maximum latitudinal extent. Species recorded in the mesophotic had a significantly greater than expected probability of also occurring in shaded microhabitats and at higher latitudes, consistent with light as a common limiting factor. The findings suggest an important role for deeper habitats, particularly depths 30-45 m, in preserving evolutionary lineages of Indo-Pacific corals. Deeper reef areas are clearly more diverse than previously acknowledged and therefore deserve full consideration in our efforts to protect the world's coral reef biodiversity. [ABSTRACT FROM AUTHOR]

Spaniomolgus is a symbiotic genus of copepods of the poecilostomatoid family Rhynchomolgidae and is known to be associated with shallow-water reef-building hermatypic corals. Three species of this genus were previously found only in washings of Acropora and Stylophora in northern Madagascar. Four coral morphotypes of Stylophora pistillata (Pocilloporidae) were collected by SCUBA at 1 to 28 m depth in five sites in the Saudi Arabian Red Sea in 2013. Copepods found on these colonies were studied using light, confocal and scanning electron microscopy. Five new, and one known, species of the genus Spaniomolgus were discovered in washings and inside the galls of the hermatypic coral S. pistillata. The description of these new species (Spaniomolgus globus sp. n., S. stylophorus sp. n., S. dentatus sp. n., S. maculatus sp. n., and S. acutus sp. n.) and a key for the identification of all of its congeners is provided herein. [ABSTRACT FROM AUTHOR]

Coral reefs have high biodiversity and are important as ecosystem engineers, providing microhabitats for a large number of organisms. This study examines the patterns of diversity, abundance and structure of gorgonian epifaunal communities found in Ecuador, a well-recognized marine biodiversity hot spot. Within this area, Leptogorgia manabiensis and L. obscura represent two of the most abundant and widely distributed gorgonian species, each with differing morphological characteristics. Epifaunal communities associated with these host species were analyzed during both the cold (June) and warm (November) seasons over two consecutive years. Both species were shown to be highly effective benthic biodiversity ecosystem engineers, hosting denser communities than other related organisms such as scleractinians, other gorgonians, algae, sponges, hydrocorals and bryozoans, as well as other geographic areas. A complex pattern of biodiversity was observed, with each gorgonian species hosting distinct communities: The fan-shaped L. manabiensis had a less diverse community dominated by echinoderms (mainly ophiuroids), while the bush-shaped L. obscura was dominated by crustaceans (mainly amphipods). Although the morphology of L. obscura allowed for greater living space for associated fauna, this species exhibited a less dense epifaunal community than of L. manabiensis. A seasonal fluctuation in abundance was also observed. Abundance tended to be greater in the cold season (June), likely due to the influence of the cold, nutrient-rich Humboldt Current, than in the warm season (November), when the warm, nutrient-poor Panama Current dominates. Diversity was not affected by seasonal fluctuations and remained constant throughout the year. [ABSTRACT FROM AUTHOR]

Biodiversity defines the variety of living organisms on this planet and is often quantified by the total number of species. However, species richness is insufficient in accounting for the differences in evolutionary history and the functions species contribute to the ecosystem. To address this shortcoming, phylogenetic diversity and functional diversity are increasingly being quantified and studied to inform ecological theory and conservation prioritisation. For scleractinian reef corals, congruence, mismatch and complementarity among different biodiversity components remain unknown, but recently available trait and phylogenetic data provide a robust test of these relationships. Here, we examine the taxonomic, functional and phylogenetic diversity of corals across a gradient of diversity in Singapore. Relationships among the biodiversity components at 25 reef sites are compared to identify patterns of mismatch or congruence for testing the precision of using one as a proxy for another. Furthermore, we examine community assembly of corals using null models derived from randomised community data. Our results show that correlations among biodiversity components are generally positive but weak, with species-dependent (non-abundance-weighted) metrics more strongly correlated with one another than species-independent (abundance-weighted) measures. No single biodiversity component could predict another precisely to be used as a reliable proxy for coral communities. Therefore, if trait diversity and evolutionary history were to be set as conservation targets, it is essential to maximise functional diversity and phylogenetic diversity explicitly when identifying areas or assemblages for management. Null models reveal the presence of more-than-expected similarities in trait combinations and evolutionary relationships among species in most reef communities. These findings suggest that environmental filtering under high levels of coastal development and sedimentation may be associated with coral community composition on Singapore’s reefs. Our approach provides new insights into the relationships between different components of coral diversity and has important applications for marine conservation planning. [ABSTRACT FROM AUTHOR]

The deep reef refugia hypothesis (DRRH) suggests that mesophotic coral ecosystems (MCEs) represent a sanctuary for various coral reef taxa from impacts of natural and anthropogenic stressors. The Pulley Ridge FL mesophotic reef was surveyed using unmanned vehicles and technical diving in 2015 and compared to vehicle surveys in 2003, to test the DRRH. The MCE sites surveyed consisted of at least 25 species of algae (~ 50% cover), 18 species of scleractinian corals (< 1% cover), 67 species of sponges (1-2% cover), in addition to 83 species of fish. The percent cover data indicate a significant decline of coral and sponges, and a significant increase in algae, relative to surveys conducted about a decade earlier. While the cause of this change is unknown, our results indicate that some mesophotic reefs may not be stable refugia for coral reef biodiversity and seed banks for resilience of damaged shallow reefs. [ABSTRACT FROM AUTHOR]

The coral crab Fungicola fagei (Decapoda: Brachyura: Cryptochiridae) is recorded for the first time from the Hawaiian Islands, where it was discovered in a previously unknown association with the solitary, free-living mushroom coral Lobactis scutaria (Anthozoa: Scleractinia: Fungiidae). The associated crab species was discovered off Hilo on the island of Hawai'i, where it appeared to be relatively common. It could have been previously overlooked because of its small size (max. ca. 1 cm long) and its hidden life style inside the host coral. Species identification is based on the morphology of the carapace and use of the cytochrome oxidase subunit I (COI ) barcode gene as molecular marker. Fungicola fagei is known from other localities in the Indo-West Pacific region, where it is only hosted by mushroom coral species of the genera Podabacia and Sandalolitha. The record of F. fagei from the Hawaiian Islands represents a northeastward extension of its known geographical distribution range, 6,000 km away from its nearest locality in Vanuatu, despite the availability of host species as eastward as the Cook Islands and French Polynesia. Because these other host species do not occur in the Hawaiian Islands, F. fagei's occurrence here is only possible because of its association with L. scutaria, uniquely recorded from Hawaii. [ABSTRACT FROM AUTHOR]

Scleractinian cold-water corals (CWCs) are one of the most important habitat engineers of the deep sea. Although the South China Sea (SCS) abuts the biodiversity center of scleractinian CWCs in the western Pacific, only a few sporadic records are available. We discovered new CWC sites by means of trawl sampling and video observation along the continental shelf of the northwestern SCS. All trawled scleractinian CWC specimens were identified to species level according to skeleton morphology and structure. The living CWCs and associated fauna recorded in the video were -identified to a higher level of classification. Scleractinian corals were identified to genus level, while non-scleractinian CWCs were identified to family level and given general names such as gorgonian corals, bamboo corals and black corals. Associated benthic dwellers were divided into major categories. A total of 28 scleractinian CWC species were identified to 7 families, 15 genera, and 1 additional subgenus. Among them, 13 species were colonial, including important habitat-forming species in the genera Eguchipsammia, Dendrophyllia and Cladopsammia. Non-scleractinian CWCs were identified to 7 families, including 4 families gorgonian corals, 1 family bamboo corals, and 2 families black corals. Gorgonian corals were the most abundant non-scleractinian CWCs in this region. Meanwhile, starfish, sea anemones, fish, gastropods, echinoderms, and other associated benthic fauna were recorded in the CWC habitats, with starfish belonging to the order Brisingida being most common. New scleractinian CWC assemblages were discovered along the continental seabed mounds in the northwestern SCS. This study highlights the remarkable diversity of cold-water scleractinian corals in the whole SCS, and shows the potential widespread distribution and conservation prospect of CWC habitats in this region. • The first study of cold-water corals was conducted in the South China Sea by the combined method of trawling and video observation. • New scleractinian CWC assemblages were discovered with high diversity along the continental seabed mounds. • The presence of CWC habitat was confirmed with many non-scleractinian CWCs and other associated benthic taxa. [ABSTRACT FROM AUTHOR]

Scleractinian corals adapt to various substrate conditions with a variety of growth morphologies and modes of life. The azooxanthellate solitary scleractinian Deltocyathoides orientalis exhibits slightly flattened, bowl-shaped corallites. This study describes in detail the modes of skeletal regeneration after fragmentation in association with exquisitely adaptive strategies of the corals for life on soft substrates. Larger fragments of individuals retaining almost two-thirds to five-sixths of the original skeletal area inherit the densely dilated, lower central skeleton, so as to keep a stable life position on soft substrates and regenerate the lost parts promptly. Even highly fragmented individuals preserving less than 10% of the original skeleton still regenerate and repair. Fragmented individuals with almost one-sixth to one-third original skeleton actively maintain a posture with the oral disc upward using movements of remaining tentacles. Damaged and missing soft tissues are then efficiently regenerated to form a mouth and gastrovascular cavity near the new centre of the corallum. Every regenerated individual reuses skeleton and soft tissues, and is capable of burrowing before the completion of growth morphology. The mode of regeneration characteristic of D. orientalis is thus effective and adaptive for maintenance of a stable life position on soft substrates for this solitary scleractinian. As fragmentation in deeper-water, soft-bottom settings is likely due to predation rather than turbulence, the rapid corallum regeneration and burrowing strategy may both represent adaptive strategies for life on soft substrates and exploitation of new niches, such as an infaunal mode of life, in a predator-rich environment. [ABSTRACT FROM AUTHOR]

Mass bleaching associated with unusually high sea temperatures represents one of the greatest threats to corals and coral reef ecosystems. Deeper reef areas are hypothesized as potential refugia, but the susceptibility of Scleractinian species over depth has not been quantified. During the most severe bleaching event on record, we found up to 83% of coral cover severely affected on Maldivian reefs at a depth of 3-5 m, but significantly reduced effects at 24-30 m. Analysis of 153 species' responses showed depth, shading and species identity had strong, significant effects on susceptibility. Overall, 73.3% of the shallow-reef assemblage had individuals at a depth of 24-30 m with reduced effects, potentially mitigating local extinction and providing a source of recruits for population recovery. Although susceptibility was phylogenetically constrained, species-level effects caused most lineages to contain some partially resistant species. Many genera showed wide variation between species, including Acropora, previously considered highly susceptible. Extinction risk estimates showed species and lineages of concern and those likely to dominate following repeated events. Our results show that deeper reef areas provide refuge for a large proportion of Scleractinian species during severe bleaching events and that the deepest occurring individuals of each population have the greatest potential to survive and drive reef recovery. [ABSTRACT FROM AUTHOR]

Shallow water zooxanthellate coral reefs grade into ecologically distinct mesophotic coral ecosystems (MCEs) deeper in the euphotic zone. MCEs are widely considered to start at an absolute depth limit of 30m deep, possibly failing to recognise that these are distinct ecological communities that may shift shallower or deeper depending on local environmental conditions. This study aimed to explore whether MCEs represent distinct biological communities, the upper boundary of which can be defined and whether the depth at which they occur may vary above or below 30m. Mixed-gas diving and closed-circuit rebreathers were used to quantitatively survey benthic communities across shallow to mesophotic reef gradients around the island of Utila, Honduras. Depths of up to 85m were sampled, covering the vertical range of the zooxanthellate corals around Utila. We investigate vertical reef zonation using a variety of ecological metrics to identify community shifts with depth, and the appropriateness of different metrics to define the upper MCE boundary. Patterns observed in scleractinian community composition varied between ordination analyses and approaches utilising biodiversity indices. Indices and richness approaches revealed vertical community transition was a gradation. Ordination approaches suggest the possibility of recognising two scleractinian assemblages. We could detect a mesophotic and shallow community while illustrating that belief in a static depth limit is biologically unjustified. The switch between these two communities occurred across bathymetric gradients as small as 10m and as large as 50m in depth. The difference between communities appears to be a loss of shallow specialists and increase in depth-generalist taxa. Therefore, it may be possible to define MCEs by a loss of shallow specialist species. To support a biological definition of mesophotic reefs, we advocate this analytical framework should be applied around the Caribbean and extended into other ocean basins where MCEs are present. [ABSTRACT FROM AUTHOR]

With the ongoing loss of coral cover and the associated flattening of reef architecture, understanding the links between coral habitat and reef fishes is of critical importance. Here, we investigate whether considering coral traits and functional diversity provides new insights into the relationship between structural complexity and reef fish communities, and whether coral traits and community composition can predict structural complexity. Across 157 sites in Seychelles, Maldives, the Chagos Archipelago, and Australia's Great Barrier Reef, we find that structural complexity and reef zone are the strongest and most consistent predictors of reef fish abundance, biomass, species richness, and trophic structure. However, coral traits, diversity, and life histories provided additional predictive power for models of reef fish assemblages, and were key drivers of structural complexity. Our findings highlight that reef complexity relies on living corals-with different traits and life histories-continuing to build carbonate skeletons, and that these nuanced relationships between coral assemblages and habitat complexity can affect the structure of reef fish assemblages. Seascape-level estimates of structural complexity are rapid and cost effective with important implications for the structure and function of fish assemblages, and should be incorporated into monitoring programs. [ABSTRACT FROM AUTHOR]

Molecular sequence data have previously revealed the existence of cryptic species associated with the Pocillopora 'damicornis-like' coral. Recently, this species complex has been reclassified into three species including the resurrected P. acuta, which appears to have a wide distribution. Morphological characteristics described for P. acuta are present in corals previously identified as Pocillopora damicornis. To determine if the Pocillopora 'damicornis-like' colonies on Singapore's reefs are P. acuta, P. damicornis, or both, we examined a new collection of Pocillopora using mitochondrial DNA data and morphology. We also compared specimen morphologies from past collections and examined the known regional distributions of both species. Our analyses show that most Pocillopora 'damicornis-like' corals in Singapore are P. acuta instead of P. damicornis. Findings here are important for coral diversity records in Singapore and will help clarify distributional limits of morphologically similar Pocillopora species. [ABSTRACT FROM AUTHOR]

Background: West coast of India is characterized by the presence of rich rocky out-crops with a diversity of poorly illuminated vertical rocky walls, crevices, caves, tunnels and overhangs. Though these are the typical environment for azooxanthellate scleratinian corals, there is no report available on these corals from this region. Methods: In situ observations including photography were made by SCUBA diving Collected specimens were soaked in fresh water and then in sodium hypochlorite solution for cleaning. Finer details of coralla were photographed using a stereoscopic microscope. Result: The present account reported three species of azooxanthellate corals namely Balanophyllia cumingii Milne Edwards & Haime, 1848, Dentrophyllia indica Pillai, 1969 and Paracyathus profundus Duncan, 1889 for the first time from the rocky out-crops off Goa, mid-west coast of India and illustrated with in situ morphological characters of the species recorded. Conclusion: Despite their rich biodiversity, the seas and the deep shelf regions adjacent to India have had few surveys and limited reports (34 species) only are available on the occurrence of azooxanthellate corals. Detailed further studies along the coast would unveil the presence of more number of species. [ABSTRACT FROM AUTHOR]