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Coral reefs are known to be one of the most diverse marine ecosystems on earth. However, these important ecosystems are heavily stressed by natural and anthropogenic activities. Environmental DNA (eDNA) metabarcoding is an innovative approach that can provide a greater diversity of taxonomic detections, non-invasive sampling, and a lower field component cost than traditional biomonitoring methods. Taiping Island (Itu Aba Island) is one of the major coral reef islands situated in the South China Sea where underwater visual surveys documented an outbreak of Crown-of-Thorns starfish (COTS) in 2021. In our study, we used eDNA metabarcoding to investigate whether there were shifts in coral communities by comparing pre- and post-COTS outbreak communities. One metabarcoding assay targeting the 18S gene and two assays targeting the ITS2 region (one of these assays specifically targeting Acroporid corals) were applied to 42 seawater samples collected in 2019 and 2021 from 12 sites around Taiping Island. Based on these three metabarcoding assays, 52 unique hard coral species were identified, corresponding to a total of 51 species in 2019 and 26 species in 2021. Our results indicated a significant decline in coral diversity but an increase in sponge diversity from the phylum porifera at Taiping Island in 2021. We suggest that these faunal shifts may be due to active feeding and disturbance of COTS at outbreak proportions that result in habitat changes. Our findings also suggest that eDNA can continue to serve as a promising tool to monitor the change in coral as well as reef-associated taxa during devastating outbreak events. [ABSTRACT FROM AUTHOR]

The capacity for natural coral reef recovery and the effectiveness of active restoration efforts are often contingent upon uncertain and understudied background variables, such as chronic predation for example. In the Maldives, small coral colonies (< 10 cm), primarily from the genera Pocillopora and Acropora (often found recolonising degraded reefs) are frequently predated on by the spiny cushion sea-star (Culcita schmideliana). Incidentally, these same corals (especially Acroporids) are often prioritised in active reef restoration practices. However, the level of risk these corallivores pose on restoration success has not yet been assessed. Here, we aimed to initially document the population densities of C. schmideliana on a degraded reef system in the Maldives (Kunfunadhoo, Baa Atoll). We then assessed their associated predatory effects on coral recruits and transplants, and explored the benefits of C. schmideliana removal on the survival of these corals. Population densities ranged between 1.2 and 3.3 individuals per 100 m2, which resulted in high predation rates on coral recruits (4 – 20%) and transplants (11 – 43%). Culcita schmideliana predation accounted for the majority of the documented mortality (85%). Where C. schmideliana were removed, a significant increase in survival for recruits (9% higher) and transplants (24% higher) was shown. Further observations linked a cessation of C. schmideliana removal to a significant rise in predation instances for previously protected corals (up to 52%). Our study therefore highlights the severe impacts of C. schmideliana predation and shows Culcita spp. population management as a viable passive solution for effective reef restoration. [ABSTRACT FROM AUTHOR]

In the face of rising global temperatures, coral reefs experience coral mass bleaching and mortality. Subtropical and mesophotic environments may represent refugia for reef corals under climate change, where they can survive and eventually recolonize degraded areas. Using a comprehensive database of fossil reefs, we empirically assess the efficacy of subtropical, deeper, and turbid mesophotic environments to restore coral reefs after past global warming events. We focus on tropical coral reefs over the last 275 million years and four rapid climate warming events, which coincided with global reef crises in the geological record. In the aftermath of such hyperthermal events, we observed an increase in the proportions of reefs occurring in deeper (blue) mesophotic environments. Additionally, we found a trend of reef distributions and coral shifting towards higher latitudes. The number of coral occurrences in turbid (brown mesophotic) environments also increased after hyperthermal events. Our results suggest that subtropical, blue, and brown mesophotic environments may have served as immediate refugia for shallow-water coral species escaping warming seawater. While the patterns of reef range shifts and the establishment of blue and brown mesophotic refugia following ancient hyperthermal events provide some hope for coral reefs under current climate change, re-establishement of background reef conditions took most times millions of years. Ante el incremento de temperatura global, los arrecifes coralinos están experimentando eventos masivos de blanqueamiento y mortalidad. Los ambientes subtropicales y mesofóticos pueden representar refugios para los corales arrecifales, en los cuales pueden escapar de los efectos del cambio climático, sobrevivir y desde allí recolonizar áreas previamente degradadas. Mediante el uso de una exhaustiva base de datos en arrecifes coralinos, en este estudio se evaluó empíricamente la eficacia de los ambientes subtropicales y mesofóticos, tanto de aguas turbias someras (marrones) como de aguas claras profundas (azules), en la recuperación de arrecifes coralinos después de eventos hipertermales en el pasado. Nuestro enfoque estuvo en los arrecifes coralinos tropicales durante los últimos 275 millones de años y cuatro eventos de calentamiento climático rápido, los cuales coinciden con crisis globales en la ocurrencia de arrecifes en el registro fósil. Como consecuencia de dichos eventos hipertermales, observamos un aumento del número de arrecifes en ambientes mesofóticos de aguas profundas (azules). Además, encontramos una tendencia en la distribución de arrecifes y corales que se desplazan hacia latitudes más altas. También se observó un aumento en el número de corales que estuvieron presentes en ambientes de aguas turbias (marrones) después de dichos eventos hipertermales. Nuestros resultados sugieren que, en el pasado, los ambientes subtropicales, mesofóticos azules y mesofóticos marrones pudieron haber servido como refugios inmediatos para las especies de coral de aguas someras, en los cuales encuentran condiciones atenuantes ante el calentamiento oceánico. Si bien los patrones de desplazamiento de los arrecifes en el rango latitudinal y el establecimiento de refugios mesofóticos de aguas marrones y azules posteriores a eventos hipertermales brindan una luz de esperanza para el futuro de los arrecifes coralinos de cara al cambio climático actual, nuestros resultados evidencian que el restablecimiento de los arrecifes puede tomar millones de años. [ABSTRACT FROM AUTHOR]

Investigating coral recruitment is critical to better understand replenishment and resilience capacities of coral reef ecosystems and to improve their conservation. Here, we examined the spatio‐temporal patterns of coral recruitment and the influence of confamilial adult coral cover in the region of Toliara, southwest Madagascar. Terracotta tiles were immersed from October to late January over a 3‐year period (2018–2021) at 10 stations located on major reef habitats. Overall recruitment rates were relatively high compared to those of other reefs in the Southwestern Indian Ocean, ranging from 219.20 recruits.m−2 in 2018–2019 to 156.30 recruits.m−2 in 2020–2021. Recruit assemblages were dominated by Acroporidae (45.5%) and Pocilloporidae (45.0%), whereas Poritidae (1.9%) and "other" recruits (3.6%) were rarely recorded. Recruitment patterns varied among stations and habitats, with higher rates in patch reef (187.06 recruits.m−2) and outer slope stations (156.99 recruits.m−2) compared to inner slope stations (108.04 recruits.m−2). With the exception of "other" recruits, recruitment rates decreased between 2018 and 2019 and 2019 and 2020, followed by an increase in 2020–2021 that reached or even exceeded initial values at some stations. The abundance of Pocilloporidae recruits was positively correlated with the cover of confamilial adult corals, highlighting potential stock–recruitment or recruitment–limitation relationships, or an aggregative settlement of young stages near the established adult colonies, whereas no such relationships were recorded for other coral family categories. This study identified sites on the outer slope and patch reefs to consider prioritizing for protection as recruitment hotspots, as well as degraded inner slope sites that could benefit from restoration, with the important caveat that any measures should be accompanied by alternative income‐generating activities through local involvement that suits the Malagasy context, such as locally marine managed areas. [ABSTRACT FROM AUTHOR]

Reef-building corals (Scleractinia, Anthozoa, Cnidaria) are the keystone organisms of coral reefs, which constitute the most diverse marine ecosystems. Since the first decoded coral genome reported in 2011, about 40 reference genomes are registered as of 2023. Comparative genomic analyses of coral genomes have revealed genomic characters that may underlie unique biological characteristics and coral diversification. These include existence of genes for biosynthesis of mycosporine-like amino acids, loss of an enzyme necessary for cysteine biosynthesis in family Acroporidae, and lineage-specific gene expansions of DMSP lyase-like genes in the genus Acropora. While symbiosis with endosymbiotic photosynthetic dinoflagellates is a common biological feature among reef-building corals, genes associated with the intricate symbiotic relationship encompass not only those shared by many coral species, but also genes that were uniquely duplicated in each coral lineage, suggesting diversified molecular mechanisms of coral-algal symbiosis. Coral genomic data have also enabled detection of hidden, complex population structures of corals, indicating the need for species-specific, local-scale, carefully considered conservation policies for effective maintenance of corals. Consequently, accumulating coral genomic data from a wide range of taxa and from individuals of a species not only promotes deeper understanding of coral reef biodiversity, but also promotes appropriate and effective coral reef conservation. Considering the diverse biological traits of different coral species and accurately understanding population structure and genetic diversity revealed by coral genomic analyses during coral reef restoration planning could enable us to "archive" coral reef environments that are nearly identical to natural coral reefs. [ABSTRACT FROM AUTHOR]

Efforts to restore coral reefs usually involve transplanting asexually propagated fast-growing corals. However, this approach can lead to outplanted populations with low genotypic diversity, composed of taxa susceptible to stressors such as marine heatwaves. Sexual coral propagation leads to greater genotypic diversity, and using slow-growing, stress-tolerant taxa may provide a longer-term return on restoration efforts due to higher outplant survival. However, there have been no reports to date detailing the full cycle of rearing stress-tolerant, slow-growing corals from eggs until sexual maturity. Here, we sexually propagated and transplanted two massive slow-growing coral species to examine long-term success as part of reef restoration efforts. Coral spat were settled on artificial substrates and reared in nurseries for approximately two years, before being outplanted and monitored for survivorship and growth for a further four years. More than half of initially settled substrates supported a living coral following nursery rearing, and survivorship was also high following outplantation with yields declining by just 10 to 14% over four years. At 6-years post-fertilisation over 90% of outplanted corals were reproductively mature, demonstrating the feasibility of restoring populations of sexually mature massive corals in under a decade. Although use of slower growing, stress tolerant corals for reef restoration may provide a longer-term return on investment due to high post-transplantation survival rates, considerable time is required to achieve even modest gains in coral cover due to their relatively slow rates of growth. This highlights the need to use a mix of species with a range of life-history traits in reef restoration and to improve survivorship of susceptible fast-growing taxa that can generate rapid increases in coral cover. [ABSTRACT FROM AUTHOR]

Petrarca is an ascothoracidan endoparasite in scleratinian dendrophyllid corals. Petrarca can stimulate coral growth, forming a gall chamber to house itself inside the coral skeleton. The diversity, molecular phylogeny and feeding ecology of Petrarca are understudied. This is the first study of Petrarca to be based on light and scanning electron microscopy to document the fine-scale external and functional morphology of its trophi and other structures. A combined molecular and morphological approach revealed at least four closely related species of Petrarca , P. goanna , P. morula , Petrarca nozawai sp. nov. and Petrarca rubus sp. nov. in Turbinaria and Astreopora corals in Asia. Carapace shape and fine morphology, ultrastructure of the antennular aesthetasc, morphological characteristics of the trophi and the shape and size of the penis rami are diagnostic characters. Several morphological characters, which are all probably synapomorphies, have been proposed to distinguish the genus Petrarca from other Ascothoracida. Mouthparts morphology of Petrarca are developed for cutting and chewing, rather than for piercing and sucking as in many other Ascothoracida. The external surface of the carapace of Petrarca is ornamented with densely packed secretory papillae used putatively for the chemical dissolution of the substrate necessary for the formation of the gall chamber. [ABSTRACT FROM AUTHOR]

The invasive sun corals Tubastraea spp. were introduced to Brazil in the late 1980s. The invasion prompted rapid changes in seascapes and local biological communities by excluding native species, particularly sessile ones. However, little is known about the impact on the mobile invertebrates. Using an experimental approach this study investigated the effects of living and dead sun corals and coral cover (50 vs. 100% covered areas) on the taxonomic composition, diversity (H') and abundance of reptant and natant macro-crustaceans and tanaids at the species level. Experimental units consisted of 60 tiles measuring 400 cm2, half and fully covered with living or dead corals which were deployed between 3 and 5 m for 12 months on concrete blocks. A total of 1346 specimens of decapods were obtained (27 native and 1 invasive species). 1059 specimens of the tanaid Chondrochelia dubia were sampled. The overall taxonomic composition was neither affected by coral condition (live or dead) nor by coral cover area. The diversity of reptant and natant species responded differently to coral condition and coral cover. The combination of dead corals and full cover accounted for the highest abundance of reptants. Natant abundance was influenced by coral cover area, irrespective of coral condition. The positive relationship between body size and abundance was statistically significant. Abundance of the obligate tube builder C. dubia was favoured by the greater availability of space on blocks half covered by corals. No signs were found of invasion meltdown in the mobile crustacean fauna. [ABSTRACT FROM AUTHOR]

Middle Jurassic reefs are known and studied from a wide range of palaeolatitudes, yet southern Tethyan reefs have been relatively understudied. The high abundance of stromatoporoids in southern Tethyan reefs was suggested to indicate a tolerance to oligotrophic and overheated waters. Recent studies affirmed the longtime hypothesis of a warm equable climate in low palaeolatitudes during the Jurassic, which could account for the documented low diversities of low-latitudinal coral reefs during this time interval. We present a case study showing possible evidence for the suggested connection between heat stress, low coral diversity and the success of stromatoporoids in the southern Tethys. The study focuses on the unique erosional depression of Makhtesh Gadol, southern Israel, which preserves a continuous section of the Callovian (Middle Jurassic). It is rich in fossils of benthic macrofauna, especially patch reefs of corals and stromatoporoids. Our quantitative analysis shows, for the first time: (1) a variation between a low- and high-diversity of coral patch reefs; and (2) a major shift from coral-dominated patch reefs in the lower part of the section to dominating stromatoporoids in the upper part. The faunal assemblage is used to reconstruct the depositional environment, indicating a shallowing upwards and increasing warmer waters. Patch reef beds showing low coral diversity are correlated with isotopic reconstructions from the same section, providing evidence for elevated water temperatures. The faunal transition from corals to stromatoporoids is correlated with a similar shift in Saudi Arabia, improving the regional correlation to the Arabian Carbonate Platform. [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]

The abundance and health of scleractinian coral communities of Hormuz Island were investigated. For this purpose, we employed 20 m line intercept transects—12 in the intertidal zone and 15 subtidally to evaluate coral cover and community composition. The estimated dead coral coverage was 6.21%±0.81%, while live coral coverage was 16.93%±1.81%, considered as very poor. Totally, 12 genera were recorded, of which Porites with 11.9%±1.4% live cover was the dominant, while Goniopora had the least cover (0.07%±0.08%). Based on Mann-Whitney U-test, live coral coverage, dead coral coverage, algal coverage, cover of other benthic organisms and abiotic components showed significant univariate differences between zones (p<0.05). The Spearman correlation test between the abundance of biotic and abiotic components indicated significant negative correlation of live coral and sand with zoantharian and significant positive correlation of algae and other benthic organisms with rubble. The reef health indices used for the corals indicated that, in general, the environmental conditions were not suitable, which could be attributed to both natural and anthropogenic factors, the most important of which was zoantharian' overgrowth on the scleractinian corals in this region. [ABSTRACT FROM AUTHOR]

Microbes play a key role in reef dynamics, mediating the competition between scleractinian corals and benthic algae; however, major shifts in bacterial communities among coral species in response to increases in the abundance of algae are not well understood. We investigated the taxonomic composition of coral-associated microbial communities under algae-overgrowth conditions using 16S rRNA gene sequencing. The results showed that non-algal (i.e., healthy) tissue (HH) had lower bacterial abundance and diversity than tissue collected from the coral–algae interface boundary (HA) and areas of algae growth (AA). Specifically, the HA and AA samples had higher relative abundances of Saprospiraceae, Rhodobacteraceae, and Alteromonadaceae. Compared with Platygyra sp. and Montipora sp., the physiological response of Pocillopora sp. was more intense under algae-induced stress based on microbial gene function prediction. Our results indicate that algal pressure can significantly alter the microbial community structure and function of coral ecosystems. Our data thus provide new insight into the relationship between corals and their microbiome under environmental stress. [ABSTRACT FROM AUTHOR]

Sea cucumbers are important ecological engineers in marine ecosystems. However, the fishery demand of some species, especially large-epifaunal and commercially used (LEC) sea cucumbers, has risen drastically, resulting in serious depletion of local populations for many species. Despite this problem, basic ecological data on sea cucumbers, such as population densities and preferred habitats, are often still insufficient. Here, we report on the population densities of multiple LEC sea cucumber species, and their ambient benthic communities at eight sites around Okinawa Islands. Further, we discuss the correspondence between sea cucumber densities and the surrounding coral communities. Our results show two sites within national or quasi-national parks, Aka and Manza, where stricter rules have been placed on fisheries and land reclamation compared to other areas, had the highest and third highest sea cucumber population densities among sites, respectively. Holothuria atra was observed at all survey sites and made up the majority of sea cucumber populations at all sites except for Chatan and Sesoko, where Holothuria leucospilota and Stichopus chloronotus were most abundant, respectively. Regarding the relationships between benthic composition and LEC sea cucumber species, S. chloronotus was significantly correlated with dead corals, scleractinian corals, and coralline algae. As well, H. leucospilota had significant correlations with rubble. Although there were no significant correlations between any specific scleractinian coral genus and sea cucumber densities, S. chloronotus was marginally insignificant with Platygyra and Psammocora. Notably, medium- to highly valued species were sparse in our surveys, and most of them appeared at only one site. Additionally, at one site (Odo), only three LEC sea cucumber individuals were observed. Combining these facts with relatively low population densities around the Okinawa Islands compared to densities reported in previous research from the Indo-West Pacific Ocean region, we conclude that Okinawan LEC sea cucumber populations have been and are being impacted by high levels of direct (e.g., overexploitation, as well as coastal development) and indirect anthropogenic pressure (e.g., decreasing water quality). To address the current situation, repeated monitoring and more detailed investigations to reveal the drivers that determine LEC sea cucumber species aggregations and population densities are urgently needed, along with more robust management of remaining LEC sea cucumber populations. [ABSTRACT FROM AUTHOR]

Using a standardized SNP array, we identified two populations of Acropora cervicornis and one population of A. palmata in the Caribbean coast of Colombia. San Andrés was the most genetically differentiated location for both species. An average pairwise FST value of 0.131 and 0.050 between San Andrés and neighboring collection sites was estimated, for A. cervicornis and A. palmata, respectively. Based on population patterns of both acroporid species, we inferred that Magdalena River is not a barrier of genetic connectivity among Colombian populations. Genetic comparisons between the Colombian coast of Caribbean with other Caribbean locations agree with previous studies for both species, where four populations were identified in A. cervicornis and three in A. palmata. Our results support published bio-physical model predictions and highlight the Panama-Colombia gyre as a possible isolating mechanism within the western Caribbean. However, the genetic diversity in both species was about half (mean HE per siteD0.321 in A. palmata and 0.369 in A. cervicornis) than previous estimates in acroporid populations in the Caribbean. The lower genetic diversity as well their relative isolation and high levels of reef degradation may be of particular conservation concern that may require species-specific management coupled with science-based restoration efforts. [ABSTRACT FROM AUTHOR]

Members of the ammonium transporter family occur in all domains of life. However, they have been characterized, at the molecular level, mainly in bacteria and plants, whereas in animals their molecular characterization is limited to a few species. In marine invertebrates, recent studies have reported a multitude of physiological functions in which ammonium could take part. Among them, calcification is one for which very few data are available. In scleractinian corals, it has been reported that external sources of ammonium and/or ammonium containing compounds enhance calcification. However, despite these physiological insights, the underlying transport mechanisms are still unknown at the molecular level. In this study, we performed a first molecular characterization of ammonium transporters in the scleractinian coral Stylophora pistillata. By performing differential gene expression analysis, through quantitative real-time PCR, we show that S. pistillata ammonium transporters possess different tissue specificities. Most notably, one ammonium transporter, spiAMT1d, is specifically expressed in the coral tissue containing the calcifying cells. Furthermore, we determined spiAMT1d subcellular localization by immunostaining S. pistillata histological cross-sections and show that it localizes on the apical side of the calcifying cells and in their intracellular compartments. Taken together our results strongly suggest a role of ammonium transporters in coral calcification and lay the groundwork for many future studies aiming to better elucidate the potential role of ammonium in calcification. [ABSTRACT FROM AUTHOR]

The article presents data indicating the relationship of the bathymetric distribution of solitary endemic scleractinian corals inhabiting the Antarctic continental shelf and upper continental slope with the vertical density of the Antarctic Circumpolar Current. The study is based on materials collected by expeditions of the Shirshov Institute of Oceanology (IO RAS) and the literature data. The results show that endemic species that appeared in the Late Neogene and Pleistocene were unable to propagate across other oceans due to the existing horizontal and vertical density of the Arctic Circumpolar Current during that period. [ABSTRACT FROM AUTHOR]

Skeletons of contemporary reef‐building scleractinian corals are formed of aragonite, a polymorph of the calcium carbonate (CaCO3), notwithstanding calcite being a more stable phase under the condition of coral habitats. Circumstances developing aragonite in coral calcification have been addressed currently. Considering that the symbiotic relationship between the coral host and dinoflagellate algae (zooxanthellae) is perhaps relevant to coral calcification, we studied the impact of these symbiotic relationships on CaCO3 polymorph selection. Juvenile scleractinian corals (Acropora tenuis and Acropora digitifera) absent symbionts were cultured in seawaters with varied Mg/Ca molar ratios (mMg/Ca), and the mineral phases of the skeletons were detected employing X‐ray diffraction. The findings revealed that diminutive quantities of calcite precipitated as coral skeleton in Acropora digitifera surprisingly in pseudo‐present seawater (mMg/Ca∼5). Additionally, coral developed skeletons from only calcite in seawater with an mMg/Ca < 1. The evidence gathered in this investigation suggests that the symbiotic relationship affects the establishment of aragonite skeletons in the course of coral calcification. Plain Language Summary: Skeletons of contemporary reef‐building corals are made of calcium carbonate. The calcium carbonates have polymorphs: calcite, aragonite, and vaterite. Aragonite is a component of coral skeletons, but calcite can thermodynamically precipitate more easily than aragonite in the living conditions of corals. Circumstances resulting in aragonite precipitation in coral calcification have been addressed recently. Considering that the symbiotic relationship between the coral host and dinoflagellate algae is perhaps relevant to coral calcification, we studied the impact of these symbiotic relationships on aragonite precipitation. Juvenile scleractinian corals without symbionts were cultured in seawater with varied Mg/Ca molar ratios to evaluate the effects of mineral component differences resulting from Mg/Ca molar ratio on calcium carbonate polymorphs. The mineral phases of the skeletons were identified using an X‐ray diffraction. The findings revealed that small quantities of calcite precipitated as coral skeleton in pseudo‐present seawater (Mg/Ca molar ratio of ∼5). Additionally, coral developed skeletons from only calcite in seawater with an Mg/Ca molar ratio of <1. The evidence gathered in this investigation suggests that the symbiotic relationship affects the establishment of aragonite skeletons in the course of coral calcification. Key Points: Reef‐building corals build their skeletons using calcium carbonate in aragonite form, which is thermodynamically less stable than calciteCorals build entirely calcitc skeletons in artificial seawater with low Mg/Ca ratio without a symbiotic relationship with zooxthantellaeA symbiotic relationship involves CaCO3 polymorph selection in coral calcification [ABSTRACT FROM AUTHOR]

In the North Patagonian fjord region, the cold-water coral (CWC) Desmophyllum dianthus occurs in high densities, in spite of low pH and aragonite saturation. If and how these conditions affect the energy demand of the corals is so far unknown. In a laboratory experiment, we investigated the carbon and nitrogen (C, N) budget of D. dianthus from Comau Fjord under three feeding scenarios: (1) live fjord zooplankton (100-2,300 µm), (2) live fjord zooplankton plus krill (>7 mm), and (3) four-day food deprivation. In closed incubations, C and N budgets were derived from the difference between C and N uptake during feeding and subsequent C and N loss through respiration, ammonium excretion, release of particulate organic carbon and nitrogen (POC, PON). Additional feeding with krill significantly increased coral respiration (35%), excretion (131%), and POC release (67%) compared to feeding on zooplankton only. Nevertheless, the higher C and N losses were overcompensated by the threefold higher C and N uptake, indicating a high assimilation and growth efficiency for the krill plus zooplankton diet. In contrast, short food deprivation caused a substantial reduction in respiration (59%), excretion (54%), release of POC (73%) and PON (87%) compared to feeding on zooplankton, suggesting a high potential to acclimatize to food scarcity (e.g., in winter). Notwithstanding, unfed corals 'lost' 2% of their tissue-C and 1.2% of their tissue-N per day in terms of metabolism and released particulate organic matter (likely mucus). To balance the C (N) losses, each D. dianthus polyp has to consume around 700 (400) zooplankters per day. The capture of a single, large krill individual, however, provides enough C and N to compensate daily C and N losses and grow tissue reserves, suggesting that krill plays an important nutritional role for the fjord corals. Efficient krill and zooplankton capture, as well as dietary and metabolic flexibility, may enable D. dianthus to thrive under adverse environmental conditions in its fjord habitat; however, it is not known how combined anthropogenic warming, acidification and eutrophication jeopardize the energy balance of this important habitat-building species. [ABSTRACT FROM AUTHOR]

The structural complexity of coral reefs provides important ecosystem functions, such as wave attenuation for coastal protection, surfaces for coral growth, and habitat for other organisms. Corals build much of this structure, but an understanding of how colonies of different species and sizes contribute to complexity is lacking. We quantified three interdependent descriptors of complexity—rugosity, fractal dimension, and height range—for reef patches as well as the corals growing upon them in Kāne'ohe Bay (O'ahu, Hawai'i). Despite similar levels of reef-scale complexity throughout the bay, we found marked differences in how species contribute to this complexity. Variation in complexity among species was closely tied to colony morphology, but not to colony size. Together, our results show that no one species is sufficient to generate the full spectrum of habitat complexities we see on coral reefs, which has direct implications for reef recovery and restoration. [ABSTRACT FROM AUTHOR]

Ocean warming is altering the biogeographical distribution of marine organisms. In the tropics, rising sea surface temperatures are restructuring coral reef communities with sensitive species being lost. At the biogeographical divide between temperate and tropical communities, warming is causing macroalgal forest loss and the spread of tropical corals, fishes and other species, termed "tropicalization". A lack of field research into the combined effects of warming and ocean acidification means there is a gap in our ability to understand and plan for changes in coastal ecosystems. Here, we focus on the tropicalization trajectory of temperate marine ecosystems becoming coral‐dominated systems. We conducted field surveys and in situ transplants at natural analogues for present and future conditions under (i) ocean warming and (ii) both ocean warming and acidification at a transition zone between kelp and coral‐dominated ecosystems. We show that increased herbivory by warm‐water fishes exacerbates kelp forest loss and that ocean acidification negates any benefits of warming for range extending tropical corals growth and physiology at temperate latitudes. Our data show that, as the combined effects of ocean acidification and warming ratchet up, marine coastal ecosystems lose kelp forests but do not gain scleractinian corals. Ocean acidification plus warming leads to overall habitat loss and a shift to simple turf‐dominated ecosystems, rather than the complex coral‐dominated tropicalized systems often seen with warming alone. Simplification of marine habitats by increased CO2 levels cascades through the ecosystem and could have severe consequences for the provision of goods and services. [ABSTRACT FROM AUTHOR]

This work provides a comprehensive description of the Scleractinian family Merulinidae (Verrill, 1865) of the Red Sea at species level based on skeletal structure for helping in evaluating and estimation of actual species diversity, as well as predicting their response to environmental changes. The present study is a first attempt to describe and illustrate the coral species of the family Merulinidae in the Farasan Islands (Saudi Arabian Coast). Moreover, coral reef terraces are investigated around El Quseir‐Marsa Alam area on the Egyptian Red Sea Coast. Overall, 42 scleractinian coral species from the family Merulinidae (Verrill, 1865) have been identified. They belong to 14 genera: Dipsastraea, Favites, Echinopora, Goniastrea, Coelastrea, Paragoniastrea, Paramontastraea, Astrea, Cyphastrea, Erythrastrea, Merulina, Platygyra, Leptoria, and Hydnophora. About 37 species are recorded for the first time from the Farasan Islands and 26 species from El Quseir‐Marsa Alam area, among them three species are recognized as new records. Two species are added to coral communities of the Red Sea (Goniastrea favulus and Paragoniastrea deformis), and six species were added to the fossil record of the Red Sea. The terminology, systematic classification, and the criteria of identification for all studied coral taxa are generally updated according to recent results. The known age and all recorded stratigraphic range of these species are illustrated and discussed. From the results, most of the corals are still living in the present Red Sea except for three species: Favites micropentagonus, Goniastrea favulus, and Paragoniastrea deformis. All species are extended down to the Pleistocene and a few to the Pliocene and Miocene. [ABSTRACT FROM AUTHOR]

Corals have evolved a variety of stress responses to changing conditions, many of which have been the subject of scientific research. However, polyp bailout has not received widespread scientific attention, despite being described more than 80 years ago. Polyp bailout is a drastic response to acute stress in which coral colonies break down, with individual and patches of polyps detaching from the colony and the calcareous skeleton Polyps retain their symbiotic partners, have dispersal ability, and may undergo secondary settlement and calcification. Polyp bailout has been described worldwide in a variety of anthozoan species, especially in Scleractinia. It can be induced by multiple natural stressors, but also artificially. Little is known about the evolutionary and ecological potential and consequences of breaking down modularity, the dispersal ability, and reattachment of polyps resulting from polyp bailout. It has been shown that polyp bailout can be used as a model system, with promise for implementation in various research topics. To date, there has been no compilation of knowledge on polyp bailout, which prompted us to review this interesting stress response and provide a basis to discuss research topics and priorities for the future. [ABSTRACT FROM AUTHOR]

With coral reefs declining globally, resilience of these ecosystems hinges on successful coral recruitment. However, knowledge of the acclimatory and/or adaptive potential in response to environmental challenges such as ocean acidification (OA) in earliest life stages is limited. Our combination of physiological measurements, microscopy, computed tomography techniques and gene expression analysis allowed us to thoroughly elucidate the mechanisms underlying the response of early-life stages of corals, together with their algal partners, to the projected decline in oceanic pH. We observed extensive physiological, morphological and transcriptional changes in surviving recruits, and the transition to a less-skeleton/more-tissue phenotype. We found that decreased pH conditions stimulate photosynthesis and endosymbiont growth, and gene expression potentially linked to photosynthates translocation. Our unique holistic study discloses the previously unseen intricate net of interacting mechanisms that regulate the performance of these organisms in response to OA. [ABSTRACT FROM AUTHOR]

Scleractinian corals exhibit a dual trophic pattern of autotrophic photosynthesis and heterotrophic predation. However, whether corals can adjust their trophic status under contrasting environmental conditions remains unclear. In our study, 70 scleractinian corals (Favia palauensis) were collected from Sanya and the Xisha and Nansha Islands in the South China Sea. We measured the zooxanthellae density (ZD) and δ13C of zooxanthellae (δ13Cz) and host tissue (δ13Ch) and analyzed the difference between δ13Ch and δ13Cz (i.e., Δh−z 13C). The relatively high ZD and δ13Cz values in the samples from Sanya indicate that these corals might have higher photosynthetic rates and autotrophic abilities than those from Xisha and Nansha. In contrast, the relatively low δ13Ch and Δh−z 13C values in the samples from Xisha and Nansha suggest that these corals might have a higher heterotrophic ability than those from Sanya. In addition, we tested the coral tissue biomass and skeletal δ13C (δ13Cs) in the samples from Sanya and examined their correlations with Δh−z 13C. The results showed a negative correlation, indicating that the more the organic material produced by the coral, the stronger its heterotrophic ability. Our results show that corals can adjust their trophic status under different environmental and physiological conditions, which is essential for increasing their adaptability to different environmental conditions. [ABSTRACT FROM AUTHOR]

The detection and control of invasive alien species in marine ecosystems is especially challenging because it is difficult to visualize the full extension of an invasion, while control options are often limited. The invasive scleractinian coral Tubastraea coccinea have spread over 8000 km of the Atlantic coastline, from Florida in the USA to southern Brazil, mainly in association with oil and gas platforms. This invasive coral threatens endemic species, reduces native coral recruitment, and modifies communities and trophic interactions, posing a relevant threat to shallow Atlantic reefs. The main aim of our study was to assess the effectiveness of an ongoing T. coccinea control program by analyzing the results of control interventions on population structure and cover of the target species in its southern Atlantic limit of distribution. We also describe the reproductive effort of T. coccinea in a 12-month time span. Between 2012 and 2019, almost 14,000 colonies were removed, most of them of small size (< 5 polyps). The highest reproductive effort was observed in September. Changes in T. coccinea cover, population structure and potential local propagule supply were observed. Control activities led to a reduction in up to half the cover of the invaded area, maintained the majority of the population in non-reproductive sizes, and consequently lowered the potential local propagule supply. Our paper highlights the fundamental role of control in preventing the local spread of T. coccinea. Recommendations on management frequency and timing are also discussed in order to contribute to the improvement of management efficiency. [ABSTRACT FROM AUTHOR]

Habitat structure increases richness and abundance of species in many environments by providing easy access to resources and refuge from predators. In coral reefs, corals are habitat for many organisms and differences in their morphologies may act as variation in habitat structure for associated fauna. In the present study, we investigate whether there are differences in the richness and abundance of molluscs associated with three species of Mussismilia corals exhibiting different growth morphologies, in two different reef areas of the Bahia state. Mussismilia harttii has a meandroid pattern, M. hispida is a massive coral, M. braziliensis also has a massive growth pattern with crevices at the corallum base. Coral characteristics were measured in the laboratory. Significant differences were identified for richness among coral species – higher values were reported in colonies of M. harttii and no significant statistical differences were observed between M. braziliensis and M. hispida. Considering the density of associated molluscs, the same pattern was found. The results are in accordance with previous studies and indicate the importance of M. harttii as a key habitat to maintain a richer and more abundant associated fauna. The internal volume of interpolypal space is an important factor influencing the richness and density of associated species. [ABSTRACT FROM AUTHOR]

The genus Acropora comprises the most diverse and abundant scleractinian corals (Anthozoa, Cnidaria) in coral reefs, the most diverse marine ecosystems on Earth. However, the genetic basis for the success and wide distribution of Acropora are unknown. Here, we sequenced complete genomes of 15 Acropora species and 3 other acroporid taxa belonging to the genera Montipora and Astreopora to examine genomic novelties that explain their evolutionary success. We successfully obtained reasonable draft genomes of all 18 species. Molecular dating indicates that the Acropora ancestor survived warm periods without sea ice from the mid or late Cretaceous to the Early Eocene and that diversification of Acropora may have been enhanced by subsequent cooling periods. In general, the scleractinian gene repertoire is highly conserved; however, coral- or cnidarian-specific possible stress response genes are tandemly duplicated in Acropora. Enzymes that cleave dimethlysulfonioproprionate into dimethyl sulfide, which promotes cloud formation and combats greenhouse gasses, are the most duplicated genes in the Acropora ancestor. These may have been acquired by horizontal gene transfer from algal symbionts belonging to the family Symbiodiniaceae, or from coccolithophores, suggesting that although functions of this enzyme in Acropora are unclear, Acropora may have survived warmer marine environments in the past by enhancing cloud formation. In addition, possible antimicrobial peptides and symbiosis-related genes are under positive selection in Acropora , perhaps enabling adaptation to diverse environments. Our results suggest unique Acropora adaptations to ancient, warm marine environments and provide insights into its capacity to adjust to rising seawater temperatures. [ABSTRACT FROM AUTHOR]

Many life history traits relate to trade-offs among an organism's energy investments in growth, reproduction, and maintenance, as well as to fundamental physiological processes or body size. Other traits reflect affordances, or possibilities enabled by an investment strategy. In scleractinian corals, growth and reproduction have been studied to a much greater extent than maintenance. Species traits likely to correlate or trade off with maintenance investments include those relating to colony growth, reproduction, and susceptibility to bleaching. Here, we measure tissue biomass per cm2 for 29 Caribbean reef corals and evaluate whether the more easily measured corallite diameter is a proxy for tissue biomass as is often assumed. We examine hypotheses concerning corallite size and tissue biomass on the one hand, and growth rate, reproduction, competitive ability, and bleaching susceptibility on the other. Our results indicate that biomass per unit area ranges from one to two orders of magnitude across species, that corallite size is a weak predictor of tissue biomass per cm2, and that tissue biomass is strongly correlated with growth rate and competitive ability. Relationships between biomass or module size and reproductive characteristics or bleaching susceptibility are not evident in this set of Caribbean corals. These findings expand our understanding about energy investment strategies in colonial corals and suggest that biomass may be an important metric to consider in cross-species comparisons, especially among corals from different families. Finally, this work can help inform predictions of reef response to continued threats. [ABSTRACT FROM AUTHOR]

Low‐diversity scleractinian corals were described systematically from the Middle Miocene Wadi Waqb Member (Jabal Kibrit Formation) in the northwest of Saudi Arabia. The fauna comprises nine species belonging to nine genera and four families: Porites sp., Favites neglecta (Michelotti in D'Achiardi, 1868), Tarbellastraea reussiana (Milne‐Edwards & Haime, 1850), Acanthophyllia ampla (Reuss, 1871), Solenastrea turonensis (Michelin, 1847), Thegioastraea roasendai Michelotti, 1871, Heliastraea oligophylla (Reuss 1871), Heliastraea sp., and Siderastrea miocenica Osasco, 1896. The identified corals were recorded previously from the Mediterranean basin, Portugal, France, Spain, Romania, Catalonia, Sardinia, Algeria, Egypt, Iran, Turin, Greece, Hungary, and Bosnia basins. The decreasing richness or diversity pattern of the fauna is attributed to the lack of possible exchange with zooxanthellate coral faunas of the Indo‐Pacific after the late Burdigalian, due to the closure of marine seaways through the Middle East by emergent areas and northward rotation of the Arabian Peninsula. [ABSTRACT FROM AUTHOR]

Copyright of Boletín de la Sociedad Geológica Mexicana is the property of Sociedad Geologica Mexicana 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.)

Protease-producing bacteria play a vital role in degrading organic nitrogen in marine environments. However, the diversity of the bacteria and extracellular proteases has seldom been addressed, especially in communities of coral reefs. In this study, 136 extracellular protease-producing bacterial strains were isolated from seven genera of scleractinian corals from Luhuitou fringing reef, and their protease types were characterized. The massive coral had more cultivable protease-producing bacteria than branching or foliose corals. The abundance of cultivable protease-producing bacteria reached 106 CFU g-1 of coral. Phylogenetic analysis of 16S rRNA gene sequences revealed that the isolates were assigned to 24 genera, from which 20 corresponded to the phyla Firmicutes and Proteobacteria. Bacillus and Fictibacillus were retrieved from all coral samples. Moreover, Vibrio and Pseudovibrio were most prevalent in massive or foliose coral Platygyra and Montipora. In contrast, 11 genera were each identified in only one isolate. Nearly all the extracellular proteases from the bacteria were serine proteases or metalloproteases; 45.83% of isolates also released cysteine or aspartic proteases. These proteases had different hydrolytic ability against different substrates. This study represents a novel insight on the diversity of cultivable protease-producing bacteria and their extracellular proteases in scleractinian corals. [ABSTRACT FROM AUTHOR]

Coral diseases are emerging as a major threat to coral reefs worldwide, and although many of them have been described, knowledge on their epizootiology is still limited. This is the case of the Halofolliculina ciliate infections, recognized as the skeletal eroding band (SEB) and Caribbean ciliate infection (CCI), two diseases caused by ciliates belonging to the genus Halofolliculina (Class Heterotrichea). Despite their similar macroscopic appearance, the two diseases are considered different and their pathogens have been hypothesized to belong to different Halofolliculina species. In this work, we analysed the morphology and genetic diversity of Halofolliculina ciliates collected in the Caribbean Sea, Red Sea and Indo-Pacific Ocean. Our analyses showed a strong macroscopic similarity of the lesions and similar settlement patterns of the halofolliculinids from the collection localities. In particular, the unique erosion patterns typical of the SEB were observed also in the Caribbean corals. Fine-scale morphological and morphometric examinations revealed a common phenotype in all analysed ciliates, unequivocally identified as Halofolliculina corallasia. Phylogenetic analyses based on nuclear and mitochondrial (COI) molecular markers consistently found all samples as monophyletic. However, although the nuclear marker displayed an extremely low intra-specific diversity, consistent with the morphological recognition of a single species, the analyses based on COI showed a certain level of divergence between samples from different localities. Genetic distances between localities fall within the intra-specific range found in other heterotrich ciliates, but they may also suggest the presence of a H. corallasia species complex. In conclusion, the presented morpho-molecular characterization of Halofolliculina reveals strong similarities between the pathogens causing SEB and CCI and call for further detailed studies about the distinction of these two coral diseases. [ABSTRACT FROM AUTHOR]

Parasites in 61 individuals of eight species of coral reef fish (Caracanthus maculatus, Scorpaenodes sp., Sebastapistes cyanostigma, Gobiodon unicolor, Paragobiodon modestus, P. echinocephalus, Pseudocheilinus hexataenia, and Halichoeres sp.) were studied in April–May 2012–2014 and November 2017. All studied fish were symbionts of corals of the genera Acropora and Pocillopora. The parasites found were the nematodes Spirocamallanusistiblenii, Raphidascaris (?) sp., and Ascarophis sp., a larva of the cestode Nybelinia sp., as well as metacercariae of the trematodes Stephanostomum sp. 1, Stephanostomum sp. 2, and Trematoda gen. sp. The low prevalence, infection rate, and diversity of parasites could be related to low population numbers of fish hosts, their efficient individual anti-parasitic defense, as well as to predation by corals that prey on dispersal stages of parasites. [ABSTRACT FROM AUTHOR]

Cold-Water Corals (CWCs), and most marine calcifiers, are especially threatened by ocean acidification (OA) and the decrease in the carbonate saturation state of seawater. The vulnerability of these organisms, however, also involves other global stressors like warming, deoxygenation or changes in sea surface productivity and, hence, food supply via the downward transport of organic matter to the deep ocean. This study examined the response of the CWC Desmophyllum dianthus to low pH under different feeding regimes through a long-term incubation experiment. For this experiment, 152 polyps were incubated at pH 8.1, 7.8, 7.5 and 7.2 and two feeding regimes for 14 months. Mean calcification rates over the entire duration of the experiment ranged between -0.3 and 0.3 mg CaCO3 g-1d-1. Polyps incubated at pH 7.2 were the most affected and 30% mortality was observed in this treatment. In addition, many of the surviving polyps at pH 7.2 showed negative calcification rates indicating that, in the long term, CWCs may have difficulty thriving in such aragonite undersaturated waters. The feeding regime had a significant effect on skeletal growth of corals, with high feeding frequency resulting in more positive and variable calcification rates. This was especially evident in corals reared at pH 7.5 (ΩA = 0.8) compared to the low frequency feeding treatment. Early life-stages, which are essential for the recruitment and maintenance of coral communities and their associated biodiversity, were revealed to be at highest risk. Overall, this study demonstrates the vulnerability of D. dianthus corals to low pH and low food availability. Future projected pH decreases and related changes in zooplankton communities may potentially compromise the viability of CWC populations. [ABSTRACT FROM AUTHOR]

Long Island and its adjoining islands of Middle Andaman archipelago are mostly covered by mangrove habitat while the eastern coastal parts of the islands are with scattered fringing reef in the continental shelf region. A total of 253 species of scleractinian corals were recorded from four islands such as Long, Guitar, Round and North Passage with the average species diversity of 3.18 and live cover of 25.28%. Globally recorded threatened 42 species of scleractinians were recorded from these study areas. The regional occurrence of the species revealed that 32.41% scleractinian were common and 24.90% corals were rare. Long Island harbors 29.42% of scleractinian coral species of Andaman and Nicobar Islands with optimum diversity (H'=4.35) especially in the eastern and south-eastern coast. The present paper focused on the status survey of scleractinian corals from these areas to monitor the health status in Middle Andaman region of Andaman and Nicobar Islands. [ABSTRACT FROM AUTHOR]

Corals are associated with dinitrogen (N2)-fixing bacteria that potentially represent an additional nitrogen (N) source for the coral holobiont in oligotrophic reef environments. Nevertheless, the few studies investigating the assimilation of diazotrophically derived nitrogen (DDN) by tropical corals are limited to a single scleractinian species (i.e., Stylophora pistillata). The present study quantified DDN assimilation rates in four scleractinian and three soft coral species from the shallow waters of the oligotrophic Northern Red Sea using the 15N2 tracer technique. All scleractinian species significantly stimulated N2 fixation in the coral-surrounding seawater (and mucus) and assimilated DDN into their tissue. Interestingly, N2 fixation was not detected in the tissue and surrounding seawater of soft corals, despite the fact that soft corals were able to take up DDN from a culture of free-living diazotrophs. Soft coral mucus likely represents an unfavorable habitat for the colonization and activity of diazotrophs as it contains a low amount of particulate organic matter, with a relatively high N content, compared to the mucus of scleractinian corals. In addition, it is known to present antimicrobial properties. Overall, this study suggests that DDN assimilation into coral tissues depends on the presence of active diazotrophs in the coral's mucus layer and/or surrounding seawater. Since N is often a limiting nutrient for primary productivity in oligotrophic reef waters, the divergent capacity of scleractinian and soft corals to promote N2 fixation may have implications for N availability and reef biogeochemistry in scleractinian versus soft coral-dominated reefs. [ABSTRACT FROM AUTHOR]

The resilience of reefs to repeated, increasingly frequent thermal disturbance is a dynamic balance between resistance and recovery pathways. The Lakshadweep archipelago in the central Indian Ocean has experienced three El Niño Southern Oscillation (ENSO) events in 1998, 2010 and 2016. Using a multi-decadal monitoring of 6 shallow reefs, we estimated reef resistance and coral recovery after each of these bleaching events. Even as the severity of each ENSO event increased over time, coral mortality decreased from 87% post-1998 to 44% after 2010 and 31% after 2016. In contrast, benthic recovery after 2010 was more protracted than after 1998, with a fourfold decrease in recovery rates between the two time periods. This has resulted in a 40% decline in absolute coral cover in the last 2 decades from 51.6% in 1998 to 11% in 2017. We examined the demographic and compositional mechanisms underlying these two recovery trajectories by monitoring coral recruitment, juvenile, and young adult compositions for 5 yr after 1998 and 2010. While coral juvenile densities were comparable after each of these disturbances, densities of fast-growing Acroporids had reduced from > 1 m−2 post-1998 to 0.09 m−2 post-2010. This was reflected in the composition of coral communities in 2003 and 2015, which differed in its dominant coral taxa, with a dramatic decline in Acropora and an increase in the cover of Porites by 2015. While the dominance of resistant taxa like Porites signals a shift to a system adapting to recurrent thermal anomalies, the reduction in fast-growing, habitat-forming corals like Acropora is driving a major decline in recovery rates with time. Given the frequency of current warming events, the increased reef resistance over the last 2 decades is likely not sufficient to also ensure gains in coral cover in Lakshadweep’s reefs. [ABSTRACT FROM AUTHOR]

Several forms of calcifying scleractinian corals provide important habitat complexity in the deep-sea and are consistently associated with a high biodiversity of fish and other invertebrates. How these corals may respond to the future predicted environmental conditions of ocean acidification is poorly understood, but any detrimental effects on these marine calcifiers will have wider impacts on the ecosystem. Colonies of Solenosmilia variabilis, a protected deep-sea coral commonly occurring throughout the New Zealand region, were collected during a cruise in March 2014 from the Louisville Seamount Chain. Over a 12-month period, samples were maintained in temperature controlled (~3.5 °C) continuous flow-through tanks at a seawater pH that reflects the region's current conditions (7.88) and an end-of-century scenario (7.65). Impacts on coral growth and the intensity of colour saturation (as a proxy for the coenenchyme tissue that covers the coral exoskeleton and links the coral polyps) were measured bimonthly. In addition, respiration rate was measured after a mid-term (six months) and long-term (12 months) exposure period. Growth rates were highly variable, ranging from 0.53 to 3.068 mm year-1 and showed no detectable difference between the treatment and control colonies. Respiration rates also varied independently of pH and ranged from 0.065 to 1.756 mmol O2 g protein-1 h-1. A significant change in colour was observed in the treatment group over time, indicating a loss of coenenchyme. This loss was greatest after 10 months at 5.28% and could indicate a reallocation of energy with physiological processes (e.g. growth and respiration) being maintained at the expense of coenenchyme production. This research illustrates important first steps to assessing and understanding the sensitivity of deep-sea corals to ocean acidification. [ABSTRACT FROM AUTHOR]

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Seven species of copepods (Copepoda, poecilostomatoida) including two new species and five new records are described as associates of two widely distributed scleractinian corals, Galaxea astreata (Lamarck 1816) and Galaxea fascicularis (Linnaeus 1767), from Dongsha atoll (Pratas Island) in the South China Sea (SCS). They are: Anchimolgus amplius nov. sp., Anchimolgus contractus Humes 1979, Anchimolgus nasutus Humes 1996, Anchimolgus tanaus Humes 1991, Clamocus spinifer Humes 1979, Karanges hypsorophus Humes 1979, and Xarifia dongshensis nov. sp. Anchimolgus amplius nov. sp. can be readily distinguished from its congeners by the following features: (1) the larger body size (1.95 mm), (2) the three digitiform processes on the convex side of the mandible, (3) the third segment of leg 4 exopod arming with four spines, (4) the slender genital double-somite, (5) the caudal ramus with ratio less than 3:1, and (6) the second segment of abdominal somites distinctly shorter than others. Xarifia dongshensis nov. sp. can be readily distinguished from its congeners by the possession of (1) the bulge on the second segment of antenna, (2) the body without lateral processes or knobs, (3) the second segment of exopod of leg 1 bearing with one spine, (4) the armature of antennule being 3, 16, 4, 2 + 1 aesthetasc, and 4 + 1 aesthetasc, (5) the caudal ramus with three terminal setae, and (6) the tip of mandible with unilateral spinules. The three records of Anchimolgus species seem to have larger body size/appendages and more digitiform lobes on the convex side of the mandible than those from the Great Barrier Reef, New Caledonia, and Moluccas. Until now, 18 species of symbiotic copepods have been known to be associated with Galaxea corals. [ABSTRACT FROM AUTHOR]

Correct identification of closely related species is important for reliable measures of gene flow. Incorrectly lumping individuals of different species together has been shown to over- or underestimate population differentiation, but examples highlighting when these different results are observed in empirical datasets are rare. Using 199 single nucleotide polymorphisms, we assigned 768 individuals in the Acropora hyacinthus and A. cytherea morphospecies complexes to each of eight previously identified cryptic genetic species and measured intraspecific genetic differentiation across three geographic scales (within reefs, among reefs within an archipelago, and among Pacific archipelagos). We then compared these calculations to estimated genetic differentiation at each scale with all cryptic genetic species mixed as if we could not tell them apart. At the reef scale, correct genetic species identification yielded lower FST estimates and fewer significant comparisons than when species were mixed, raising estimates of short-scale gene flow. In contrast, correct genetic species identification at large spatial scales yielded higher FST measurements than mixed-species comparisons, lowering estimates of long-term gene flow among archipelagos. A meta-analysis of published population genetic studies in corals found similar results: FST estimates at small spatial scales were lower and significance was found less often in studies that controlled for cryptic species. Our results and these prior datasets controlling for cryptic species suggest that genetic differentiation among local reefs may be lower than what has generally been reported in the literature. Not properly controlling for cryptic species structure can bias population genetic analyses in different directions across spatial scales, and this has important implications for conservation strategies that rely on these estimates. [ABSTRACT FROM AUTHOR]

Five species of Xarifia copepods are known to live in association with the coral family, Euphylliidae Alloiteau, 1952. In this paper, three Xarifia copepods, including two new species and one species new to Taiwan, are described and redescribed, i.e., Xarifia lyudaoensis nov. sp. and Xarifia gracilipes Humes and Dojiri, 1983 living on Euphyllia glabrescens (Chamisso and Eysenhardt, 1821), and Xarifia angusta nov. sp. collected from Euphyllia ancora Veron and Pichon, 1980. The present report brings the total number of species of Xarifiidae to 95, and seven of them live in association with the coral family Euphylliidae. A comparison table and a key to the species of Xarifia from euphylliid corals are given herein. [ABSTRACT FROM AUTHOR]

The Sharm Obhur reefs have predominantly been populated by soft corals. Notably, the highest soft coral percentages were observed in the central region of the creek at Site 9 and Site 6, where anthropogenic activities are higher. Among the scleractinian corals, more non-acroporid corals such as Porites and Goniastrea were found at all study sites and were commonly observed in the creek entrance area. More acroporid corals were found at Site 7. The sedimentation rate of Sharm Obhur strongly influences the reef ecosystem. Site 9 continuously receives murky water from stormwater drainage channels and has the highest sedimentation rate in the creek, which kills most of the corals in the vicinity. Similarly, the dead end of Sharm Obhur (Site 8) also receives drainage water from the Wadi Al Kura channel, which makes this the second highest sedimentation zone of the creek. Although anthropogenic disturbances are higher in the creek, the diversity of the scleractinian corals is found to be remarkable. In this pilot study, 13 families, 34 genera and 66 species of scleractinian corals were identified. [ABSTRACT FROM AUTHOR]

The increasing interest in 3D morphological approaches for addressing evolutionary and ecological questions has driven the need for reliable, efficient, and easily accessible methods for shape quantification and complexity characterization. This applies in particular to irregularly shaped organisms, such as stony corals, which are challenging to study using traditional morphometric analyses., A potential approach to assess shape and spatial complexity of 3D documented organisms are 3D fractal dimension analyses that combine information from various spatial scales, thus enabling a holistic shape quantification. Therefore, the latest 3D scanning technology and fractal dimension analyses were used to test the performance of this novel combination of methods for quantifying inter- and intraspecific differences in shape and spatial complexity of highly irregularly shaped organisms. As model taxa, six widespread species of stony corals were used, belonging to the genera Acropora, Pocillopora and Porites. First, high-resolution shape models of coral colonies were generated using 3D structured light scanning. Then the univariate fractal dimension D and the multivariate multiscale fractal dimension as well as two traditional univariate morphological measures (surface-volume ratio and rugosity) were calculated. Finally all parameters were tested for significant interspecific and intraspecific differences, and the discriminative power of the two fractal dimension and the two traditional measures were assessed., The results show that 3D shape analyses based on fractal dimensions can be used to quantify both inter- and intraspecific variations in irregularly shaped organisms such as corals. Compared to traditional methods, fractal dimensions performed at least as good at the interspecific level and considerably better at the intraspecific level., This study demonstrates that 3D fractal dimension analyses are an efficient and easily applicable method for shape quantification and complexity characterization of irregularly shaped organisms, such as stony corals. Given the specific properties of fractal dimensions, they may either serve as an alternative complexity measure or as an additional characteristic for studying irregularly shaped organisms. Ultimately, fractal dimensions may provide a more integrative understanding of morphological variation within an ecological and evolutionary context, and could open up new opportunities for semi-automatic or automatic species determination based on 3D morphological images. [ABSTRACT FROM AUTHOR]

Five corals belonging to common scleractinian reef-building species, and collected from Gulf of Suez, Egypt were subjected to neutron activation analysis. The content of 26 elements: Na, Mg, Cl, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, As, Br, Rb, Sr, Sb, I, Cs, Ba, La, Ce, Gd, Hf, Th, and U was experimentally determined. Ca and Sr have the highest content i.e. 38.4-39.5% and 0.73-0.78% respectively while, the content of all other elements was within the ranges reported for the worldwide corals. For a better understanding of the coral exoskeleton elemental content, the partition coefficient calculated for all determined elements showed a wide range of values varying from 2 × 10 in the case of Cl to 2 × 10 for Ce and other insoluble elements. Although all corals were collected in the vicinity of the Port Suez no traces of anthropogenic contamination were evidenced. [ABSTRACT FROM AUTHOR]

In situnurseries have been a crucial part of coral reef restoration initiatives for the past two decades. However, the advantages over direct transplantation in sedimented waters has yet to be examined. In the present study, we showed thatPachyseris speciosaandPocillopora damicornisfragments reared inin situnurseries (NR) in Singapore’s sedimented waters grew significantly faster (by three to five times) than those which were directly transplanted (DT) onto the substrates. The increased growth rate during the nursery phase augmented the size of NR transplants, and had a flow-on effect on their performance during the post-transplantation phase. Overall, the maximum diameter of the NR transplants was 1.8–2.7 times larger than DT transplants after 11 months. The growth enhancement of the nursery-reared transplants improved the cost-effectiveness of our restoration effort: the estimated cost per centimetre growth of NR transplants was one-fifth of the DT corals despite the additional costs incurred to construct the nurseries. These results highlight that coral nurseries are beneficial to reef restoration in chronically sedimented waters. [ABSTRACT FROM AUTHOR]

The future of coral reefs under increasing CO2 depends on their capacity to recover from disturbances. To predict the recovery potential of coral communities that are fully acclimatized to elevated CO2, we compared the relative success of coral recruitment and later life stages at two volcanic CO2 seeps and adjacent control sites in Papua New Guinea. Our field experiments showed that the effects of ocean acidification (OA) on coral recruitment rates were up to an order of magnitude greater than the effects on the survival and growth of established corals. Settlement rates, recruit and juvenile densities were best predicted by the presence of crustose coralline algae, as opposed to the direct effects of seawater CO2. Offspring from high CO2 acclimatized parents had similarly impaired settlement rates as offspring from control parents. For most coral taxa, field data showed no evidence of cumulative and compounding detrimental effects of high CO2 on successive life stages, and three taxa showed improved adult performance at high CO2 that compensated for their low recruitment rates. Our data suggest that severely declining capacity for reefs to recover, due to altered settlement substrata and reduced coral recruitment, is likely to become a dominant mechanism of how OA will alter coral reefs. [ABSTRACT FROM AUTHOR]

The recovery of bleached corals is crucial in ensuring the persistence of the coral reef ecosystem function. This study investigated whether relocating bleachedPlatygyra sinensiscolonies was a viable measure to accelerate their recovery. During a mild bleaching event in 2014, eight bleached colonies ofP. sinensiswere relocated from an affected reef at Sultan Shoal, Singapore, to a reef at Kusu that was less impacted. Another eight colonies at Sultan Shoal were tagged as controls. After five months, 88% of relocated bleached colonies at Kusu showed full recovery whereas only 25% of the control bleached colonies at Sultan Shoal had recovered. The differential coral recovery among the two sites was most likely due to lower seawater temperatures and faster water flow at Kusu, which helped to mitigate the effects of thermal stress on the bleached corals. This relocation study demonstrated that relocating bleachedP. sinensisto sites with more favourable environmental conditions is a viable approach to reduce bleaching impacts for this species. [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]

In 2002, bleaching was reported throughout many Indo-Pacific coral-reef regions, including French Polynesia. Bleaching occurred again in French Polynesia in 2003, providing an opportunity to compare the effects of successive bleaching events on coral susceptibility. During 2002 and 2003, underwater video surveys were completed in stations at four depths (lagoon: 0-2, 2-4 m; outer reef slope: 6-8, 12-14 m) at two locations on the northern and northwestern coast of Moorea (Society Archipelago) to compare the cover of healthy-appearing, the cover of partially bleached and the cover of fully bleached coral. Bleaching patterns were genus specific and differences in susceptibility among major genera were generally consistent between 2002 and 2003, with Acropora showing the greatest susceptibility. Some genera exhibited substantial spatial variability in bleaching susceptibility between years (e.g. Pocillopora, Montipora); however, this variability was significant only for fully bleached and partially bleached Acropora. Multivariate analyses showed that spatial patterns in the proportion of healthy-appearing coral were similar over time within the assemblages, whereas the cover of partially bleached and the cover of fully bleached coral were more variable among depths and locations. This variability has important implications for assessing changes to coral community structure over time and for estimating coral-reef resistance and resilience to future bleaching disturbance. [ABSTRACT FROM AUTHOR]