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The Lakshadweep archipelago constitutes a major coral region of India but still lacks sufficient biodiversity data owing to its remoteness and a low number of faunal studies in the past. The present paper describes two new Pseudoceros species collected from Agatti Island, Lakshadweep, India. Pseudoceros bipurpurea sp. nov. and Pseudoceros galaxea sp. nov. are described based on external and internal characters, supported with histological studies and photographs. Pseudoceros bipurpurea sp. nov. is characterized by a cream background colour and an orange median line surrounded by dense patches of purple spots, which tend to disperse and broaden towards the posterior end. Pseudoceros galaxea sp. nov. displays a brown background colour with numerous white to cream dots covering almost the entire dorsal surface and a thin black margin. This study adds two new species to the polyclad fauna in Indian waters, raising the count to 68 species. An updated checklist of polyclads from Indian coast is also provided.

A Gram-stain-positive, aerobic, motile, coccus-shaped bacterium, designated strain SCSIO 13315T, was isolated from mucus of the coral Galaxea sp. collected from Luhuitou fringing reef (Sanya, Hainan, PR China). Analysis of the 16S rRNA gene sequence showed that strain SCSIO 13315T exhibits 95.5 % 16S rRNA gene sequence similarity to Pseudokineococcus basanitobsidens SKC1-2T, 95.8 % to Pseudokineococcus lusitanus T2A-S27T and 96.4 % to Pseudokineococcus marinus KST3-3T. Results of phylogenetic analysis suggested that strain SCSIO 13315T was a member of the genus Pseudokineococcus . The DNA G+C content of strain SCSIO 13315T was 73.5 %. Chemotaxonomic assessment of strain SCSIO 13315T showed that the menaquinones were MK-8(H4) and MK-9(H2). The main cellular fatty acids were anteiso-C15 : 0, C16 : 0 and summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c). The polar lipids present were diphosphatidylglycerol, phosphatidylglycerol, two unknown phospholipids, four unidentified aminolipids and one unidentified lipid. Based on the phylogenetic and phenotypic analysis, it was evident that strain SCSIO 13315T represents a novel species of the genus Pseudokineococcus , for which the name Pseudokineococcus galaxeicola sp. nov. is proposed. The type strain is SCSIO 13315T (=NBRC 109944T=DSM 27812T).

Due to current greenhouse gas emissions, Malaysian coral reefs are predicted to experience severe annual coral bleaching events by 2043, threatening the survival of coral reefs within this century. However, there is no field data on how Malaysian coral reefs respond to successive events of coral bleaching. Despite the notion that many scleractinian taxa exhibit increased thermal tolerance over the last decade, it remains unresolved whether these changes are a result of ‘weeding out’ thermally susceptible species and actually ameliorate accelerating warming rates and increasing frequencies of heat disturbances. Moreover, complex interaction of environmental and biological factors that underlie differences in the bleaching response necessitate conducting studies at the within-reef scale (i.e., leeward shallow, windward shallow). Here, we studied two successive thermal stress events starting during the 2019 El Niño Southern Oscillation (ENSO), and determined bleaching trajectories of 29 hard coral taxa across fine spatio-temporal gradients in Northeast Peninsular Malaysia. Analysis of climate trajectories affirms accelerating warming rates (0.17°C per decade) and higher return-frequency of heat disturbance. Despite high annual maximum temperatures above the putative bleaching threshold (31.07°C and 31.74°C, respectively), accumulated thermal stress was low during both bleaching episodes (Degree Heating Weeks of 1.05°C-weeks and 0.18°C-weeks, respectively), suggesting widespread thermal sensitivity of hard coral taxa (55.21% and 26.63% bleaching incidence in 2019 and 2020, respectively). However, significant discrepancies between satellite and in-situ temperature data were found (0.63°C; SD±0.26). Bleaching severity was highly taxon-specific, varied across and within reef scales due to wind exposure and depth (e.g., less bleaching at shallow windward sites), and partially contrasted historical bleaching observations (e.g., Acropora and Montipora were less susceptible, Cyphastrea, Echinopora, Goniastrea, Heliopora and Porites were highly susceptible). While bleaching severity was higher in 2019, Galaxea and Leptastrea were bleaching more in 2020 despite lower heat stress, suggesting negative legacy effects of the 2019 bleaching event on these taxa. In conclusion, hard corals were subjected to more frequent heat stress during the last decade and remain highly vulnerable to marine heatwaves across all biophysical reef scales. Annual coral bleaching impacted all hard coral taxa and reduced thermal tolerance in at least two taxa.

Widespread coral bleaching occurred in the central Red Sea in 2010 and 2015. During both events, a cross-shelf and depth gradient of bleaching severity was identified within the Thuwal reef system, central Red Sea, Saudi Arabia. While bleaching and survival of coral taxa were monitored, neither in situ reef temperatures nor coral-associated algal communities (family Symbiodiniaceae) were characterized. Here, we determined coral host-associated Symbiodiniaceae communities and monitored temperatures along the same cross-shelf and depth gradient on six reefs in 2017 to better understand the role of these factors in the observed bleaching patterns and to generate a baseline for further studies. We characterized > 600 coral–algal associations across winter and summer in six genera of scleractinian coral (Pocillopora, Stylophora, Seriatopora, Galaxea, Gardineroseris, and Porites) and one fire coral (Family Milleporidae) using ITS2 next-generation sequencing in conjunction with the SymPortal analytical framework. We show that previous bleaching patterns correlate poorly with the largely coral host-specific structure of the 2017 Symbiodiniaceae community and are in better agreement with absolute and intraday sea water temperature variations monitored on the reefs. We demonstrate a greater distinctiveness of Symbiodiniaceae communities at the more severely bleached inshore reefs compared to those reefs further offshore. However, the potential Symbiodiniaceae community changes at these reefs prior to our sampling prevent us from evaluating this distinctiveness as determinative of the differences in bleaching severities. Based on our analyses, we discuss how fine-scale delineation of algal genotypes, including host-specific putative genotypes of Durusdinium trenchii that represent alluring targets for further taxonomic identification, corroborate a niche-adapted rather than generalist character of many coral–Symbiodiniaceae associations. In conclusion, as studies such as this one continue to build the global catalogue of coral–Symbiodiniaceae associations, we may be afforded a better oversight of how specialized coral–algal associations really are and how restricted their modification may be, both of which are critical considerations in predicting the adaptive potential of corals and the reef ecosystems they build.

Coral reefs along the Malacca Straits (MS) are poorly developed mainly due to turbidity and sedimentation. This study describes the health status and community structure of the corals in Cape Rachado, West Coast of Peninsular Malaysia (WCPM), utilizing the Coral Video Transect (CVT) technique. All the survey transects were categorized as ‘fair’ coral conditions (27.39 ± 5.41%–48.56 ± 18.96%) with the reef floor mainly covered by corals and sediment. Twelve families of coral comprised of 25 distinct genera were identified. Coral communities were differentiated into four clusters with each being predominated by Galaxea, Diploastrea, Fungia and Pectinia respectively. Among all, Pectinia is the most spectacular genera and dominated the survey area. Along the MS, Favia, Favites and Porites are commonly found while Porites and Pectinia dominated the reefs. Low coral cover and diversity was recorded in MS as compared to the reefs in the South China Sea (SCS). The most prominent results include changes in the dominant coral from Porites to Pectinia while some species such as Acropora were absent from the study area. Based on the presented data, the reef in the study area was predominantly occupied by sediment and the coral communities were formed by a species with a high tolerance to turbidity and sedimentation.

Background Coral reefs are among the most diverse, complex and densely populated marine ecosystems. To survive, morphologically simple and sessile cnidarians have developed mechanisms to catch prey, deter predators and compete with adjacent corals for space, yet the mechanisms underlying these functions are largely unknown. Here, we characterize the histology, toxic activity and gene expression patterns in two different types of tentacles from the scleractinian coral Galaxea fascilcularis – catch tentacles (CTs), used to catch prey and deter predators, and sweeper tentacles (STs), specialized tentacles used for territorial aggression. Results STs exhibit more mucocytes and higher expression of mucin genes than CTs, and lack the ectodermal cilia used to deliver food to the mouth and remove debris. STs and CTs also express different sensory rhodopsin-like g-protein coupled receptors, suggesting they may employ different sensory pathways. Each tentacle type has a different complement of stinging cells (nematocytes), and the expression in the two tentacles of genes encoding structural nematocyte proteins suggests the stinging cells develop within the tentacles. CTs have higher neurotoxicity to blowfly larvae and hemolytic activity compared to the STs, consistent with a role in prey capture. In contrast, STs have higher phospholipase A2 activity, which we speculate may have a role in inducing tissue damage during territorial aggression. The expression of genes encoding cytolytic toxins (actinoporins) and phospholipases also differs between the tentacle types. Conclusions These results show that the same organism utilizes two distinct tentacle types, each equipped with a different venom apparatus and toxin composition, for prey capture and defense and for territorial aggression.

Coral tissue thickness (CTT) is an effective indicator of the adaptability of corals to environmental stress, but the relationships between the spatial and intergeneric variation of coral tissue across latitudes and tolerance to environmental stress are not well understood. To investigate this, the CTT of 768 specimens of 10 typical coral genera and surrounding seawater parameters were measured in six coral reef regions (CRRs) across the 9-22°N latitudes in the South China Sea (SCS). Results showed significant differences in CTT between different genera of corals and CRRs. CTTs were significantly higher in the northern SCS than in the southern SCS. There was also notable intergeneric variation, with the abundance of branching Acropora and foliaceous Pavona being significantly lower than that of massive Porites, Galaxea, Favia, Favites, Hydnophora, Platygyra, and encrusting Montipora, Psammocora across these CRRs. Redundancy analysis showed that dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP), sea surface temperature (SST), turbidity, and transparency were the main factors affecting CTT. Overall CTT, irrespective of genus, was significantly positively correlated with DIN, SRP, and latitude, but was significantly negatively correlated with transparency and SST. Further analysis suggested that corals in the southern SCS are mainly threatened by thermal stress, whereas in the northern SCS, corals have often suffered from destructive anthropogenic disturbance. Although seawater conditions were normal during on-site investigation, a large number of branching corals (e.g., Acropora corals) have been lost in the last several decades due to destructive human activity. In contrast, massive and encrusting corals may have higher energy reserves and photo-protective capacities due to their thicker tissues, and consequently have higher tolerance to environmental stress. Therefore, the coral communities of the SCS have gradually been transformed from branching corals to massive/encrusting corals.

This study evaluated the status of coral communities at the fringing reefs in the northern South China Sea, and their potential role in maintaining nearby coastline stability of northeastern Hainan Island (Puqian Bay, Hainan Bay). Thirty-nine coral species were recorded with mean coral cover of 5.3%, and are dominated by massive Galaxea, Platygyra and Porites. The coral communities were clustered into two groups (Clu-HNB and Clu-PQB) corresponding to different stable coastal conditions. Coral communities at the Hainan Bay with higher diversity and greater cover corresponded to relatively stable coastline, whereas those at the southern Puqian Bay (with the lowest coral diversity and spatial coverage) corresponded to severe coastline erosion. This work provides some direct evidence that declined coral reefs would weaken their functions to maintain a stable coastline, resulting in severe coastal erosion. It is also useful to help coastal managers and local people pay more attention to the importance of coral reefs in coastal protection and encourage them to change their ways to get sustainable use of coral reef resources. It may be beneficial to inspire or initiate coastal engineering to manage coasts with natural coral reef solution.

The Indonesian Ministry of Marine Affairs and Fisheries aims to establish export quota ornamental corals based on scientifically-founded data from the natural environment. The purpose of this study was to determine the abundance of ornamental coral after mass die off in 1997. Ornamental corals were classified into three groups based on the guideline of ornamental coral propagation for trading purposes. Classification categories are rapid (3-6 months), middle (8-12 months), and slow growth rate (>24 months), which relates to their harvesting time when transplanted for the trade purpose. The survey method used line intercept transects to get coral condition data and belt transect with 2 m width to get ornamental coral data. Both line and belt transect have 30 m length and with three replicates. The study showed number of colony and abundance of ornamental coral for fast growth rate group such as Acropora sp (1348 col & 7.49 col/m2), Galaxea sp, Hydnophora exesa, H. microconus, Pocillopora damicornis, Stylopora sp and Montipora sp with the highest abundant found on Acropora sp and Montipora sp (1348 col & 7.49 col/m2). Whereas the coral which from middle growth rate were Leptoseris sp, Pavona sp, Platygyra sp, Favia sp, Favites sp with the highest abundant found on Favia sp (101 col & 0.56 col/m2). Coral species typically used for ornamental coral trade within the slow growth rate category such massive coral were not found on this survey. Due to the massive coral die-off in 1997 and the paucity of ornamental corals, the utilization of ornamental coral should be supported by coral transplantation and the broodstock of slow growth of coral taken from other area. Keywords: ornamental coral, abundant, mass die off, Padang Waters

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.

Stony corals (Scleractinia) form the basis for some of the most diverse ecosytems on Earth, but we have much to learn about their evolutionary history and systematic relationships. In order to improve our understanding of species in corals we here investigated phylogenetic relationships between morphologically defined species and genetic lineages in the genus Galaxea (Euphyllidae) using a combined phylogenomic and phylogeographic approach. Previous studies revealed the nominal species G. fascicularis included three genetically well-differentiated lineages (L, S & L+) in the western Pacific, but their distribution and relationship to other species in the genus was unknown. Based on genomic (RAD-seq) and mitochondrial sequence data (non-coding region between cytb and ND2) we investigated whether the morphological taxa represent genetically coherent entities and what is the phylogenetic relationship and spatial distribution of the three lineages of G. fascicularis throughout the observed species range. Using the RAD-seq data, we find that the genus Galaxea is monophyletic and contains three distinct clades: an Indo-Pacific, a Pacific, and a small clade restricted to the Chagos Archipelago. The three lineages of G. fascicularis were associated with different RAD-seq clades, with the ‘L’ lineage showing some morphological distinction from the other two lineages (larger more asymmetrical polyps). In addition to these, three more genetic lineages in G. fascicularis may be distinguished – a Chagossian, an Ogasawaran, and one from the Indian-Red Sea. Among nominal taxa for which we have multiple samples, G. horrescens was the only monophyletic species. The mitochondrial non-coding region is highly conserved apart of the length polymorphism used to define L, S & L+ lineages and lacks the power to distinguish morphological and genetic groups resolved with genomic RAD-sequencing. The polyphyletic nature of most species warrants a careful examination of the accepted taxonomy of this group with voucher collections and their comparison to type specimens to resolve species boundaries. Further insight to the speciation process in corals will require international cooperation for the sharing of specimens to facilitate scientific discovery.

This study has assessed the reef community characteristics so as to describe the community change following a severe threat and adaptively manage coral reefs in response to the 2016 and future bleaching events. The study was conducted in Misali, Bawe, Chumbe, and Mnemba reefs in Zanzibar. Misali reef is located in Pemba Island, whereas the remaining three reefs are located in Unguja Island. The composition of the benthic cover within plots was assessed using the 20-m-long line intercept method. Each site had two plots at least 150 m apart. Four transects were randomly placed within each plot. A total of 63 benthic categories, summarized into 8 major groups, hard corals (49 categories), soft corals, sponges, algae (5 categories), corallimorpharians, hard substrates (4 categories), soft substrate, and others, were monitored. Hard corals were assessed at genus level to improve biodiversity change detection. Coral bleaching levels and coral size class distribution were assessed. A belt transect of 25 m × 1 m was used to sample for coral colonies larger than 10 cm in diameter, whereas sampling for corals smaller than 10 cm, which were considered as recruits, was done using six 1 m2 quadrats located along the transect, at fixed intervals of 0, 5, 10, 15, 20, and 25 m. Four transects per plot were sampled out. The results showed that prevalence of bleaching among surveyed reefs varied between 74% (Misali) and 88% (Bawe). However, the effect of bleaching to coral cover loss was more pronounced in Bawe (37%) and Chumbe reef (19%). Genus Acropora was the most affected coral with higher relative proportions of dead colonies for Misali (85%), Chumbe (63%), and Mnemba (43%) and Porites for Bawe (39%). Genus Porites at Bawe and Acropora at Misali and Mnemba have temporarily lost their dominance to Echinopora, Galaxea, and Porites, respectively. Coral diversity was highest in Misali for both adult and recruit populations and was lowest in Bawe reef. Geographical location, coral community composition, diversity, and reef topography are suggested to be among the determinants of variability in coral bleaching prevalence and impact to coral cover loss.

Population connectivity resulting from larval dispersal is essential for the maintenance or recovery of populations in marine ecosystems, including coral reefs. Studies of species diversity and genetic connectivity within species are essential for the conservation of corals and coral reef ecosystems. We analyzed mitochondrial DNA sequence types and microsatellite genotypes of the broadcast‐spawning coral, Galaxea fascicularis, from four regions in the subtropical Nansei Islands in the northwestern Pacific Ocean. Two types (soft and hard types) of nematocyst morphology are known in G. fascicularis and are significantly correlated with the length of a mitochondrial DNA noncoding sequence (soft type: mt‐L; hard type: mt‐S type). Using microsatellites, significant genetic differentiation was detected between the mitochondrial DNA sequence types in all regions. We also found a third genetic cluster (mt‐L+), and this unexpected type may be a cryptic species of Galaxea. High clonal diversity was detected in both mt‐L and mt‐S types. Significant genetic differentiation, which was found among regions within a given type (F ST = 0.009–0.024, all Ps ≤ 0.005 in mt‐L; 0.009–0.032, all Ps ≤ 0.01 in mt‐S), may result from the shorter larval development than in other broadcast‐spawning corals, such as the genus Acropora. Nevertheless, intraspecific genetic diversity and connectivity have been maintained, and with both sexual and asexual reproduction, this species appears to have a potential for the recovery of populations after disturbance.

Coral reefs are significant ecosystems. The ecological success of coral reefs relies on not only coral-algal symbiosis but also coral-microbial partnership. However, microbiome assemblages in the South China Sea corals remain largely unexplored. Here, we compared the microbiome assemblages of reef-building corals Galaxea (G. fascicularis) and Montipora (M. venosa, M. peltiformis, M. monasteriata) collected from five different locations in the South China Sea using massively-parallel sequencing of 16S rRNA gene and multivariate analysis. The results indicated that microbiome assemblages for each coral species were unique regardless of location and were different from the corresponding seawater. Host type appeared to drive the coral microbiome assemblages rather than location and seawater. Network analysis was employed to explore coral microbiome co-occurrence patterns, which revealed 61 and 80 co-occurring microbial species assembling the Galaxea and Montipora microbiomes, respectively. Most of these co-occurring microbial species were commonly found in corals and were inferred to play potential roles in host nutrient metabolism; carbon, nitrogen, sulfur cycles; host detoxification; and climate change. These findings suggest that the co-occurring microbial species explored might be essential to maintain the critical coral-microbial partnership. The present study provides new insights into coral microbiome assemblages in the South China Sea.

Transcriptomic resources for coral species can provide insight into coral evolutionary history and stress-response physiology. Goniopora columna, Galaxea astreata, and Galaxea acrhelia are scleractinian corals of the Indo-Pacific, representing a diversity of morphologies and life-history traits. G. columna and G. astreata are common and cosmopolitan, while G. acrhelia is largely restricted to the coral triangle and Great Barrier Reef. Reference transcriptomes for these species were assembled from replicate colony fragments exposed to elevated (31°C) and ambient (27°C) temperatures. Trinity was used to create de novo assemblies for each species from 92–102 million raw Illumina Hiseq 2 × 150 bp reads. Host-specific assemblies contained 65 460–72 405 contigs, representing 26 693–37 894 isogroups (∼genes) with an average N50 of 2254. Gene name and/or gene ontology annotations were possible for 58% of isogroups on average. Transcriptomes contained 93.1–94.3% of EuKaryotic Orthologous Groups comprising the core eukaryotic gene set, and 89.98–91.92% of the single-copy metazoan core gene set orthologs were complete, indicating fairly comprehensive assemblies. This work expands the complement of transcriptomic resources available for scleractinian coral species, including the first reference for a representative of Goniopora spp. as well as species with novel morphology.

The ability to estimate coral age using soft tissue would be useful for population biology or aging studies on corals. In this study, we investigated whether telomere length can be used to estimate coral age. We applied single telomere length analysis to a colonial coral, Galaxea fascicularis, and estimated telomere lengths of specific coral chromosomes at different developmental stages. If the telomere shortened at each cell division, the telomere length of the coral would be longest in sperm and shortest in adult colonies. However, the mean telomere length of sperm, planula larvae, and polyps was approximately 4 kb, with no significant differences among the developmental stages. The telomerase restriction fragment (TRF) analysis also showed no significant difference in the mean TRF length among the developmental stages. Our results suggested that telomere length is maintained during developmental stages and that estimating the age of colonial coral based on telomere length may not be possible. However, our findings can be used to examine avoidance of aging and rejuvenation during regeneration and asexual reproduction in colonial corals.

Investigations of the geomorphic and sedimentary context in which turbid zone reefs exist, both in the modern and fossil reef record, can inform key ecological debates regarding species tolerances and adaptability to elevated turbidity and sedimentation. Furthermore, these investigations can address critical geological and palaeoecological questions surrounding longer-term coral-sediment interactions and reef growth histories. Here we review current knowledge about turbid zone reefs from the inner-shelf regions of the Great Barrier Reef (GBR) in Australia to consider these issues and to evaluate reef growth in the period prior to and post European settlement. We also consider the future prospects of these reefs under reported changing water quality regimes. Turbid zone reefs on the GBR are relatively well known compared to those in other reef regions. They occur within 20 km of the mainland coast where reef development may be influenced by continual or episodic terrigenous sediment inputs, fluctuating salinities (24-36 ppt), and reduced water quality through increased nutrient and pollutant delivery from urban and agricultural runoff. Individually, and in synergy, these environmental conditions are widely viewed as unfavourable for sustained and vigorous coral reef growth, and thus these reefs are widely perceived as marginal compared to clear water reef systems. However, recent research has revealed that this view is misleading, and that in fact many turbid zone reefs in this region are resilient, exhibit relatively high live coral cover (>30%) and have distinctive community assemblages dominated by fast growing (Acropora, Montipora) and/or sediment tolerant species (Turbinaria, Goniopora, Galaxea, Porites). Palaeoecological reconstructions based on the analysis of reef cores show that community assemblages are relatively stable at millennial timescales, and that many reefs are actively accreting (average 2-7 mm/year) where accommodation space is available, despite recent anthropogenic pressures. These turbid zone reefs challenge traditional views on the environmental conditions required for active reef growth, but given their proximity to land and associated stresses, current knowledge on these less well understood reefs should be synthesised to aid coastal management directives. Terrigenous sediments are a dominant influence on turbid zone reef occurrence, composition and growth, and, therefore, the assessment of their future prospects will require a detailed understanding of the sedimentary regimes under which they occur and of their differential response modes.

Galaxea, Journal of Coral Reef Studies 13: 29-34(2011) Abstract Quantifi cation of zooxanthellae densities in tissues of reef-building corals aids in the assessment of the extent and severity of coral bleaching. Various meth- ods are available to quantify zooxanthellae densities; how ever, a direct comparison of these techniques has yet to been done. Here, we compare estimates of zooxanthellae densities obtained using conventional airbrushing coupled with post-tissue-blasting surface area determination, ver- sus a technique whereby zooxanthellae densities are quantifi ed from a known area (0.25 cm 2 ) of tissue after corals have been fi xed and decalcifi ed. Estimates of zoo- xanthellae densities obtained were correlated across re- plicate colonies (R 2 =0.40, n=81), and both techniques revealed similar patterns of variation among locations. The main benefi t of the decalcifi cation technique was reduced processing time, because the technique eliminates the time-consuming process of tissue blasting and re- trospective estimates of surface area. We estimate that decalcifi cation halves the processing time per sample, and produces a more accurate estimate of zooxanthellae density.

The coral symbiosis is the linchpin of the reef ecosystem, yet the mechanisms that promote and maintain cooperation between hosts and symbionts have not been fully resolved. We used a phylogenetically controlled design to investigate the role of vertical symbiont transmission, an evolutionary mechanism in which symbionts are inherited directly from parents, predicted to enhance cooperation and holobiont fitness. Six species of coral, three vertical transmitters and their closest horizontally transmitting relatives, which exhibit environmental acquisition of symbionts, were fragmented and subjected to a two-week thermal stress experiment. Symbiont cell density, photosynthetic function and translocation of photosynthetically fixed carbon between symbionts and hosts were quantified to assess changes in physiological performance and cooperation. All species exhibited similar decreases in symbiont cell density and net photosynthesis in response to elevated temperature, consistent with the onset of bleaching. Yet baseline cooperation, i.e. translocation of photosynthate, in ambient conditions and the reduction in cooperation in response to elevated temperature differed among species. Although Porites lobata and Galaxea acrhelia did exhibit the highest levels of baseline cooperation, we did not observe universally higher levels of cooperation in vertically transmitting species. Post hoc sequencing of the Symbiodinium ITS-2 locus was used to investigate the potential role of differences in symbiont community composition. Interestingly, reductions in cooperation at the onset of bleaching tended to be associated with increased symbiont community diversity among coral species. The theoretical benefits of evolving vertical transmission are based on the underlying assumption that the host-symbiont relationship becomes genetically uniform, thereby reducing competition among symbionts. Taken together, our results suggest that it may not be vertical transmission per se that influences host-symbiont cooperation, but genetic uniformity of the symbiont community, although additional work is needed to test this hypothesis.

In a search for suitable coral species and fixing methods in coral transplantation and to elucidate environmental factors affecting survival and growth of corals, we conducted experimental transplantations in the moat (shallow lagoon) of Kuta beach, Bali. On 20 limestone substrates set in the moat, we transplanted each 40 pieces of 10 species of corals. Coral pieces were fixed using either a spring or a cable tie. Corals used for experiments consisted of Acropora (4 spp.), Montipora (3 spp.), Hydnophora (1 sp.), Galaxea (1 sp.) and Pocillopora (1 sp.). These corals were obtained from a coral farm in Bali. Corals were transplanted on substrates, and underwater working time was also measured. Monitoring for more than 2 years was continued intermittently for coral survival, growth, effect of environmental factors on the survival, etc.

Prevalence and distribution of coral disease were surveyed in three impacted sites at Red Sea coast. Prevalence were significant difference between studied reefs (ANOVA; F = 10.777, p < 0.0001). Sites closed to oil pollution (sites 1 and 2) displayed much higher levels of disease prevalence (25.3% ± 8.3 2 and 18.5% ± 3.1, respectively), than site 3 that close to landfilling (12.9% ± 2.1). Totally, 99coral braches, representing 20 species affected by at least 12 diseases. However, site 3 is characterized by the highest diversity (Simpson’s Index = 0.081) and highest percentage cover of life coral (35.2% ± 11.4) showed the lowest coral diseases number (3). In opposite, 10 coral diseases were recorded at site 1, and 8 coral diseases at site 2. While, the coral disease atramentous necrosis attained the highest prevalence percentage at sites 1 and 2 (3.2% and 4.5%, respectively), did not recorded at site 3. Sediment damage disease recorded the highest prevalence percentage at site 3 (5.1%), but did not record at sites 1 and 2. Diseases having lowest percentage cover were white band disease (sites 1 and 2) and white tips disease. The most commonly distributed disease (atramentous necrosis) infected five corals in site 1 and six corals in site 2. The least commonly distributed disease (white tips) infected only two corals (Acropora humilis and Acropora formosa) at site 3. The genus Porites at sites was particularly vulnerable to all diseases. However, Galaxea fasicularis at site 3 recorded the highest percent cover of sediment damage disease. Coral disease atramentous necrosis is always associated with Vermetidae predation and Tridacna boring. While, Drupels predation is associated with skeletal eroding band. Aggressive filamentous algal overgrowth is associated with sediment damage disease at site 3. The pathogenic bacterium isolated from the diseased Stylophora pistillata, Porites sp., and Acropora sp., referred to as Vibrio fischeri.

Selected coral reefs were monitored to assess the current status of the reefs in Southern coast of Sri Lanka. The underwater visual census (UVC) survey was conducted in September to November 2014 at seven selected sites. i.e., Hikkaduwa, Rumassala, Weligama, Mirissa, Polhena, Dondra and Tangalle in the Southern coast, namely. Line intercept transect method (LIT) was used to estimate the coral and sessile benthic cover categories. Total of 84 surveys transects, four transects for each site at three replicates were deployed at shallow depth between 1 to 3 m. Environmental parameters were obtained to support the diversity observations. Percentages of sessile benthic categories (live coral, dead coral, coral rubble, rock, sand/silt) showed a significant differences among surveyed sites. The highest mean coral cover was observed at Weligama (64.75%±17.71) followed by Mirissa (49.97%±11.26), Polhena (21.57%±7.83), Hikkaduwa (19.68%±3.83), Dondra (17.31%±7.84), Rumassala (12.5%±5.59) and Tangalle (5.08%±7.66). The highest mean dead coral cover was at Hikkaduwa (36.05%±5.34) while the highest mean coral rubble cover was observed at Polhena (31.95%±9.37). Altogether 14 coral groups were recorded including Acropora sp., Pocillopora sp., Favia sp., Montipora sp., Millepora sp., Goniastrea sp., Favites sp., Podabacia sp., Pachyseris sp., Pavona sp., Leptoria sp., Porites sp., Galaxea sp. and Echinophora sp. From which the abundant species were Acropora sp., Montipora sp., and Pocillopora sp. The highest mean Shannon diversity indices (H‟) for coral groups showed at Mirissa (1.297±0.149) while the highest mean Evenness was at Rumassala (0.895±0.054).Temperature, DO, salinity, conductivity measurements were in acceptable levels which are favorable for reef growth. The TDS/TSS, concentrations of nitrate and phosphate in all sites were greater than the critical levels for a sound reef health. Most of the Southern coastal waters were observed degrading due to sedimentation, excess growth of calcareous alga Halimeda sp., destructive fishing practices, coral trampling and poor coastal management practices causing negative impacts in these reefs. These findings emphasise that the need for adopting effective management and conservation measures to protect the high coral diversity in Southern coastal waters of Sri Lanka. Keywords: Coral reefs, Southern Sri Lanka, Environmental parameters, Coral reef monitoring, Human disturbancesc

The occurrence and distribution of the coral disease Skeleton Eroding Band (SEB) has been studied at the Jordanian coast in the Gulf of Aqaba, the northernmost extension of the Red Sea. The SEB syndrome is caused by the colonial, heterotrich ciliate Halofolliculina corallasia: an advancing front of these protists destroys polyps, coenosarc, and surface of the coenosteum. In recent years SEB was registered in reefs of Australia, Mauritius, and the Red Sea. Along the Jordanian coast, disease frequency at four study sites was investigated and afflicted coral genera and species were documented. The study sites were MSS (Marine Science Station)-north, MSS-south, the tourist area near the middle of the coast, and the industrial area adjacent to the Saudi Arabian border. Corals and infections were counted inside randomly placed 1 m2 frames in reef flats and in 5, 10, and 15 m depths. In order of increasing affectedness of sample sites, MSS-south was the healthiest (12%, 4%, 4%, 16% of infected corals from shallow to deep), followed by MSS-north (19%, 28%, 24%, 24%), the tourist area (51%, 23%, 16%, 41%), and the industrial area (14%, 30%, 39%, 31%). By far the most frequently encountered coral species were Acropora spp. and Stylophora sp., while relative infection-rates were highest among Seriatopora sp. (75%), as well as Stylophora sp., Hydnophora sp., and Galaxea sp. (50% each). This was followed in steadily decreasing order from 44% to 5% by Pocillopora, Mycedium, Montipora, Echinopora, Acropora, Lobophyllia, Goniastrea, Millepora, Platygyra, Fungia, Favia, Porites, Goniopora, Favites, and Pavona. SEB was found to a depth of 30 m, but may occur even deeper.

Reef corals are likely to have many subtle but four gross responses to anomalous warm water. These are (1) not bleach and live (mortality 20%), (3) bleach and live, and (4) bleach and die. The frequency of these four possible gross responses was determined for 18 common coral taxa over an exceptionally warm 1998 El Nino where intense bleaching was observed, and mortality determined from line transects averaged 41.2±34.7 (±SD). Field studies included (1) recording the loss of color (bleaching) and observing recently dead individuals among 6,803 colonies during five sampling periods and (2) estimating mortality based on 180 m of line-intercept transects completed 4 months before and near the end of the bleaching episode. There was no clear relationship between the loss of color and either direct observation or transect-based estimates of mortality for the 18 taxa. The morphology of the taxa did not influence color loss but branching and encrusting taxa had higher mortality than massive and submassive taxa. Loss of color and mortality are the most common responses to warm water as only Pavona did not lose color or die and only two taxa, Cyphastrea and Millepora, did not significantly lose color but died. Of the 15 taxa that lost color, five taxa, Astreopora, Favia, Favites, Goniopora, and Leptoria, did not die. These taxa are those most likely to have reduced potential mortality by the loss of pigments and associated algal symbionts. Death of the branching taxa was detected reasonably by direct field observation but some taxa were underestimated when compared with mortality estimates based on line transects. Death of encrusting and massive taxa including Echinopora, Galaxea, Hydnophora, Montipora, Platygyra, and massive Porites was poorly detected from direct observations but they proved to have modest to high mortality (20–80%) based on line transects. There was no single response of these common corals to warm water but these data, collected during an extreme warm-water anomaly, indicate that the loss of color is most frequently a sign of morbidity, particularly for branching and encrusting taxa.

The surface concentration dynamics of Ca(2+) and O(2) in the scleractinian coral Galaxea fascicularis were investigated by means of 2 mm-sized sensors (mini-electrodes). Mini-electrodes were used to measure the light-regulated uptake of Ca(2+) for calcification, and the secretion of O(2), produced by photosynthesising zooxanthellae, at the surface of the oral ectoderm of Galaxea polyps. The concentration of Ca(2+) measured in the boundary layer of seawater adjacent to the polyp surface was variable but always higher than in bulk seawater in the dark and fell to levels closer to the value in bulk seawater on illumination. The fall in concentration, representing an influx of Ca(2+) into the ectoderm, increased with increasing photosynthetic photon flux density of illumination. The decrease in Ca(2+) concentration on illumination was insensitive to ruthenium red but sensitive to verapamil and acetazolamide. Oxygen secretion at the ectoderm, manifested by an increase in O(2) concentration in the boundary layer, increased on illumination but was not sensitive to any of the inhibitors used in the calcium experiments. The results suggest that Ca(2+) uptake involves calcium channels and is coupled in someway to the uptake of inorganic carbon for calcification. Uptake is also strongly coupled to photosynthesis.

In order to restore disturbed coral reefs, transplantation of coral fragments or coral heads has been conducted in many parts of the world. We reviewed methods and results of the transplantation experiments described in numerous previous reports in order to determine recommendable methodologies. Problems that should be solved by future studies are discussed. For transplantation, generally, small pieces of coral are taken from the donor colony using hammer, chisel and the like. If the collection site is far from the transplantation site, fragments should be placed in bucket full of seawater. There are various methods to fix the coral fragment onto substrate, e. g. by means of epoxy cement, plastic coated wire and nails. They should be chosen according to size and shape of coral fragments, but we found fixation with nails and cable ties is easy and reliable for staghorn corals. The cost of transplantation with a density of 245, 000 fragments per hectare secured by means of nails and cable ties has been estimated at about 36, 000, 000 JPN Yen. So far, species of the genera Acropora, Porites, Pavona and Galaxea were most frequently used for transplantation as they have relatively high survival rates.

Since the early 1960s increased soil erosion due to changing land-use practices in the Sabaki River catchment basin, has increased river-sediment discharge into coastal waters around Malindi, Kenya. Line transect surveys of shallow (< 5 m at low tide) coral reef communities were conducted in 1985–1988 and 1992–1993 on a gradient of sediment influence in the Watamu (low influence) and Malindi (intermediate and high influence) National Marine Parks. Total algal cover increased between surveys only at the control (low sediment) reef, to levels comparable to the sediment influenced reefs. Within algal categories (turf, calcareous, fleshy and coralline) there were no consistent differences among treatment groups consistent with sediment influence. Soft coral and sponge cover were higher at increasing levels of sediment influence, though this trend is confounded by a parallel increase in water motion. Coral cover increased significantly over time at the intermediate reef, to levels comparable to the low and high-sediment influenced reefs. Generic richness, diversity and dominance of corals were broadly similar among all reefs except for higher dominance in the control reef. Positive correlation between differences in coral genus abundance and differences in mean coral colony sizes over time and among reefs suggests a suite of sediment-tolerant (Echinopora, Galaxea, Hydnophora, Millepora and Platygyra) and sedimentintolerant (Favia, Montipora and Pocillopora) genera. Acropora, Astreopora, Favites and Porites were intermediate between these groups. Reefs exposed to high sediment influence were dominated by sediment tolerant and intermediate coral genera during both surveys, while reefs exposed to low sediment influence were dominated by sediment-intolerant and intermediate genera. Overall, although there were changes in some of the parameters listed above, and in coral genus abundance patterns, no evidence for decreased diversity and ecological health of sedimentinfluenced reefs could be found for our set of community-level measurements of the shallow-water coral assemblage.

Summary Many scleractinian coral species host epizoic acoelomorph flatworms, both in aquaculture and in situ. These symbiotic flatworms may impair coral growth and health through light-shading, mucus removal and disruption of heterotrophic feeding. To quantify the effect of epizoic flatworms on zooplankton feeding, we conducted video analyses of single polyps of Galaxea fascicularis (Linnaeus 1767) grazing on Artemia nauplii in the presence and absence of symbiotic flatworms. 18S DNA analysis revealed that flatworms inhabiting G. fascicularis belonged to the genus Waminoa (Convolutidae), which were hosted at a density of 3.6±0.4 individuals polyp−1. Polyps hosting flatworms exhibited prey capture rates of 2.2±2.5, 3.4±4.5 and 2.7±3.4 nauplii polyp−1 30 min−1 at prey concentrations of 250, 500 and 1,000 nauplii L−1, respectively. Polyps that had their flatworms removed displayed prey capture rates of 2.7±1.6, 4.8±4.1 and 16.9±10.3 nauplii polyp−1 30 min−1. Significant main and interactive effects of flatworm presence and ambient prey concentration were found, reflected by the fact that flatworms significantly impaired host feeding rates at the highest prey density of 1,000 nauplii L−1. In addition, flatworms displayed kleptoparasitism, removing between 0.1±0.3 and 0.6±1.1 nauplii 30 min−1 from the oral disc of their host, or 5.3±3.3 to 50.0±2.1% of prey acquired by the coral. We suggest classifying the coral-associated Waminoa sp. as an epizoic parasite, as its presence may negatively affect growth and health of the host.

A new species of shrimp Metapontonia scorpio symbiotic with scleractinian coral Diploastrea heliopora is described from Taiwan. The species belongs to the smallest symbiotic shrimps of the family Palaemonidae. It is remarkable by a unique ability to turn its last two pleonites with tail fan dorsally over the 4 th and preceding pleonal segments, thus resembling scorpions. For such movement, the respective opposing dorsal margins of the 4 th –6 th segments are deeply concave. The new species is characterized by a short dorsally directed rostrum, incomplete orbit, semicircular scaphocerite, and medially concave basal antennular segment. The only species of the genus, M. fungiacola , is compared with the new species based on morphology and DNA. Metapontonia fungiacola is for the first time reported from Taiwan and Papua New Guinea. The morphological and colour variability of the species is discussed. The scleractinian corals Platygyra lamellina (Merulinidae), Lobophyllia hemprichii , cf. Micromusa sp., Symphyllia cf. radians (Lobophylliidae), and Galaxea sp. (Oculinidae), are new host records for the species.

The extra-thecal epithelia of cryofixed undecalcified, freeze-substituted polyps of the scleractinian corals Galaxea fascicularis and Tubastrea faulkneri and axial and basal polyps of Acropora formosa have been examined, in anhydrously prepared thick slices, by confocal laser scanning light microscopy. The avoidance of chemical fixation and decalcification makes it possible to determine whether previously seen structures are real or artefactual products of swelling, shrinkage and distortion. All of the epithelia of all the corals examined are characterised by well defined intercellular spaces. Mucocytes are present in all cell layers in Galaxea and Tubastrea but are not present in any cell layers in the axial polyp of Acropora although they are abundant in the oral ectoderm of the basal polyps in this coral. Zooxanthellae are absent in Tubastrea, the epithelia of the exert septa of Galaxea and the axial polyp of Acropora. The calicoblastic ectoderm is generally composed of thin squamous cells with large intercellular spaces. At rapidly calcifying regions such as the tips of the exert septa of Galaxea, the calicoblastic cells are elongated with extensive arborisation of the basal regions of the cells. They are separated by large intercellular spaces and contain numerous fluorescent granules. The apical regions of these cells appear to be closely applied to the surface of the skeleton. There is no evidence of a space between the apical region of the calicoblastic cells and the skeleton.

Scleractinian corals provide a set of complex habitats for a diversity of associated animals that often form close interactions with their hosts. Studies of specialized coral associates have focused on the biology of decapod crustaceans (Patton 1994), while only Spirobranchus spp. (Serpulidae) have been considered among polychaetes (Stella et al. 2011). Species of another polychaeta family, Polynoidae (scaleworms), are common symbionts of octocorals, although they were also reported as accidental associates on scleractinians. Their relationship with corals remains virtually unknown (Martin & Britayev 1998). Here, we consider an association and diet of an undescribed species of scaleworm Hololepidella sp. with the coral Galaxea astreata (Oculinidae). Specimens of Hololepidella were found in washings from G. astreata colonies in the Bay of Nhatrang, Vietnam. Scaleworms were semitransparent and hardly distinguishable on their hosts (Fig. 1a, b). They reach 35 mm in length and live under the canopy of coral tentacles. Seventy-four of 101 inspected colonies harboured Hololepidella. Infested colonies could have up to five worms per colony, while 91 % of these colonies had only one or two scaleworms per colony. Out of 30 scaleworms that we have dissected, five had no food remains. Others contained mucus with unicellular algae and cnidocysts (23 specimens, Fig. 1c, d), and fragments of copepods (seven specimens). Copepods resemble Hetairosyna wedensis (Fig. 1e), which is an obligatory symbiont of Galaxea species (Humes 1996). The algae were similar in size, shape and color to the zooxanthellae of Galaxea, which indicates that the scaleworms are feeding on other coral symbionts as well as

BackgroundThe coral skeleton consists of CaCO3deposited upon an organic matrix primarily as aragonite. Currently galaxin, fromGalaxea fascicularis, is the only soluble protein component of the organic matrix that has been characterized from a coral. Three genes related togalaxinwere identified in the coralAcropora millepora.ResultsOne of theAcroporagenes (Amgalaxin) encodes a clear galaxin ortholog, while the others (Amgalaxin-like 1andAmgalaxin-like 2) encode larger and more divergent proteins. All three proteins are predicted to be extracellular and share common structural features, most notably the presence of repetitive motifs containing dicysteine residues. In situ hybridization reveals distinct, but partially overlapping, spatial expression of the genes in patterns consistent with distinct roles in calcification. Both of theAmgalaxin-likegenes are expressed exclusively in the early stages of calcification, whileAmgalaxincontinues to be expressed in the adult, consistent with the situation in the coralGalaxea.ConclusionComparisons with molluscs suggest functional convergence in the two groups; lustrin A/pearlin proteins may be the mollusc counterparts of galaxin, whereas the galaxin-like proteins combine characteristics of two distinct proteins involved in mollusc calcification. Database searches indicate that, although sequences with high similarity to the galaxins are restricted to the Scleractinia, more divergent members of this protein family are present in other cnidarians and some other metazoans. We suggest that ancestral galaxins may have been secondarily recruited to roles in calcification in the Triassic, when the Scleractinia first appeared. Understanding the evolution of the broader galaxin family will require wider sampling and expression analysis in a range of cnidarians and other animals.

We compared the bleaching and mortality response (BMI) of 19 common scleractinian corals to an anomalous warm-water event in 1998 to determine the degree of variation between depths, sites, and regions. Mombasa corals experienced a greater temperature anomaly than those on the Great Barrier Reef (GBR) sites and this was reflected in the greater BMI response of most taxa. Comparing coral taxa in different sites at the same depth produced high correlation coefficients in the bleaching response in Kenya at 2 m (r=0.86) and GBR at 6 m depth sites (r=0.80) but less in the GBR for shallow 2 m sites (r=0.49). The pattern of taxa susceptibility was remarkably consistent between the regions. Coral taxa explained 52% of the variation in the response of colonies to bleaching between these two regions (Kenya BMI = 0.90 GBR BMI + 26; F(1,19)=18.3; p

1. On the coral reefs of the Tulear region (S. W. Madagascar), the feeding behaviour of sea stars, in particular the speciesCulcita schmideliana has been studied. It feeds in its usual biotope, the sea-grass beds of the inner reef flats, on the epibenthic film of the substrates, of the leaves, but also commonly on sponges, mainly the symbioticGellius cymiformis (associated withCeratodictyon spongiosum); 2. In the moat (residual pools, coral-built formations) of the inner reef flat where the population was poor in 1965 but equal to that of the sea-grass bed in 1972, the cushion sea star feeds on the epibenthic felt, but also on the living corals (Galaxea, Goniopora) and on soft corals(Xenia). This latter diet is very close to that of the Pacific cogeneric species,Culcita novaeguinae. 3.Acanthaster planci populations are normal on the reef flats of the region (but a little more dense on the fringing reef under silty deposits). Only a beginning of an infestation was observed in May 1972, but it disappeared later (condition 6 of Chesher's classification). 4. Others Oreasterids feed mainly on epibenthic film, extruding their stomachs on the substrates.Protoreaster nodosus has a larger distribution thanP. lincki, Pentaceraster mammillatus andChoriaster granulosus. 5. Among others sea stars,Asterina burtoni seems to be a large predator of species living under dead coral blocks (sponges, ascidiacea) of the boulder tracts and of the rubbly flats.

1. 1. Calcium deposition in Galaxea fasricularis was found to be an active process. 2. 2. The poisoning effect of DCMU showed that the process was enhanced by the photosynthetic activity of the endosymbiont it houses. 3. 3. Various poisons and metabolic inhibitors examined reduced calcium incorporation, suggesting the probable involvement of Ca 2+ -ATPase and carbonic anhydrase with ATP as the possible energy source. 4. 4. Calcium deposition is enhanced by light, is temperature dependent and is a function of external magnesium concentration.

A high sedimentation event caused by dredging and dumping of sediment was recorded on Xiaodonghai Reef in Yulin Bay, southern Hainan Island, China. Significantly high sedimentation and constant light shading were observed during the sediment dumping event (SD Event). Using long-term video transects, we quantified coral community changes and responses to the SD Event between 2008 and 2010. The SD Event caused severe coral mortality on Xiaodonghai Reef at a depth of 6 m, while corals at 3 m were less affected. Total live coral cover at 6 m decreased from 54.3% to 14.8%, and Diploastrea heliopora replaced Galaxea fascicularis as the dominant coral species at 6 and 9 m. The density of juvenile corals also declined after the SD Event, especially for the genera Galaxea and Platygyra. However, the density of juvenile Porites and Pocillopora spp. slightly increased. Monitoring for 11 months after the SD Event indicated no recovery of coral communities on Xiaodonghai Reef. Long-term video transect data also revealed that mean live coral cover dramatically declined, from 30.5% in 2008 to 9% in 2010, while the dominant corals in Yulin Bay shifted to more tolerant coral species, such as massive Porites spp. and D. heliopora. The rapid coral community degradation in Yulin Bay between 2008 and 2010 was probably caused by high sediment deposition resulting from intensive dredging and land-clearing activities. These results highlight the necessity for an integrated watershed management to control sediment deposition on near-shore coral reefs.

A fossil colony of the shallow-water, hermatypic scleractinian coral Galaxea clavus (Dana) was collected by research submersible in situ from a prominent terrace 175 m below present sea level along the margin of the Australian continental shelf. Radiometric ages obtained from the original skeletal aragonite indicate that sometime between 13,000 and 17,000 years ago, sea level was glacioeustatically lowered to at least -175 m. Oxygen isotope ratios of carbonate from the fossil Galaxea reflect both seawater temperature and the isotopic composition of seawater at the time the coral was alive. Limits can be placed on these parameters, however, by considering the minimum temperature for the distribution of modern Galaxea, and the maximum increase in seawater 18O resulting from the transfer of water from ocean to continental ice sheets during glaciation. Although the 18O values of fossil carbonates by themselves cannot be interpreted in terms of paleotemperature, the combined use of geochemical, biological, and oceanographic data severely restricts the possible range for values of paleotemperature and 18O of seawater. In-situ sampling of reef corals drowned by the rapid rise of sea level associated with the latest period of deglaciation can yield valuable paleoenvironmental information. In particular, it should be possible to partition the 18O/16O ratio of such samples into two components, one representing deposition temperature, and the other reflecting the oxygen isotopic composition of ambient seawater.