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Aim: Revealing how diversity varies across the depth gradient is key for understanding the role of mesophotic coral ecosystems in the functioning of coral reefs. We quantitatively examined how alpha and beta generic diversity of scleractinian coral assemblages vary across a wide depth gradient for coral reefs. Location: Sixteen sites in eight islands of three archipelagos in French Polynesia. Methods: We studied generic diversity patterns of scleractinian corals, as derived from the analysis of photo‐quadrats, across the seafloor from shallow to lower mesophotic depths (6–120 m) and on a wide geographic scale. Our sampling considered quantitative coral cover to explore the patterns of alpha and beta components of diversity across depth and horizontal space. Results: We show that in French Polynesia, mesophotic coral ecosystems host higher alpha and beta generic diversity than shallow reefs despite decreasing coral cover with depth. The variation of coral genus richness across the depth gradient is mainly driven by a mid‐domain effect with a peak at 40 m depth. At the same time, we found that the differences in coral genera across islands (spatial beta‐diversity) increased steadily along the depth gradient. Main conclusions: Our findings report the first quantitative results of coral cover and diversity from mesophotic coral ecosystems in French Polynesia and also present one of the few existing studies to examine the broad breadth of the mesophotic depth gradient. We demonstrate that mesophotic depths can host unexpectedly high generic richness of scleractinian coral assemblages. At the same time, we showed that increasing depth increases the differences in generic diversity composition across islands, whereas shallow reefs are similar in between. While a single island could conserve shallow regional biodiversity, mesophotic depths containing the richest diversity require site‐specific measures, suggesting that considering these mesophotic depths in conservation is necessary to maintain regional diversity. [ABSTRACT FROM AUTHOR]

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

Abstract: Recent phylogenetic analyses have demonstrated the limits of traditional coral taxonomy based solely on skeletal morphology. In this phylogenetic context, Faviidae and Mussidae are ecologically dominant families comprising one third of scleractinian reef coral genera, but their phylogenies remain partially unresolved. Many of their taxa are scattered throughout most of the clades of the Robust group, and major systematic incongruences exist. Numerous genera and species remain unstudied, and the entire biogeographic area of the Indian Ocean remains largely unsampled. In this study, we analyzed a portion of the mitochondrial cytochrome c oxidase subunit 1 gene and a portion of ribosomal DNA for 14 genera and 27 species of the Faviidae and Mussidae collected from the Indian Ocean and New Caledonia and this is the first analysis of five of these species. For some taxa, newly discovered evolutionary relationships were detected, such as the evolutionary distinctiveness of Acanthastrea maxima, the genetic overlap of Parasimplastrea omanensis and Blastomussa merleti, and the peculiar position of Favites peresi in clade XVII together with Echinopora and Montastraea salebrosa. Moreover, numerous cases of intraspecific divergences between Indian Ocean and Pacific Ocean populations were detected. The most striking cases involve the genera Favites and Favia, and in particular Favites complanata, F. halicora, Favia favus, F. pallida, F. matthaii, and F. rotumana, but divergence also is evident in Blastomussa merleti, Cyphastrea serailia, and Echinopora gemmacea. High morphological variability characterizes most of these taxa, thus traditional skeletal characteristics, such as corallite arrangement, seem to be evolutionary misleading and are plagued by convergence. Our results indicate that the systematics of the Faviidae and the Mussidae is far from being resolved and that the inclusion of conspecific populations of different geographical origin represents an unavoidable step when redescribing the taxonomy and systematics of scleractinian corals. More molecular phylogenies are needed to define the evolutionary lineages that could be corroborated by known and newly discovered micromorphological characters. [Copyright &y& Elsevier]

The morphometric and molecular boundaries between twelve Psammocora (Cnidaria, Scleractinia) nominal species were addressed. The type specimens of Psammocora haimiana, P. togianensis, P. folium, P. digitata, Maeandroseris australiae, P. samoensis, P. superficialis, P. profundacella, P. nierstraszi, P. verrilli, and P. albopicta, were analysed together with specimens from museum collections, including those depicted in widely cited taxonomic descriptions, and material collected for this study in different parts of the Indo-Pacific. Morphometric analyses of the dimensions of skeletal structures allowed the identification of groups of specimens with similar morphologies. Congruency between these groups and current species whose synonymies and descriptions were found in recent taxonomic references was, hence, investigated and the species revised. Finally, the phylogenetic relationships of a representative subset of specimens were reconstructed based on rDNA and COI, thus allowing a direct link between morphologic and genetic information. Incongruence between type of morphology and literature descriptions was evidenced for some widely recognised species. Based on this integrated approach, five species were unambiguously identified. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, , 421-456. [ABSTRACT FROM AUTHOR]

Samples of Siderastrea collected by the geologist C. F. Hartt during expedition to Brazil (19th century), and deposited at the National Museum of the Natural History, Smithsonian Institution, have been re-examined. Taxonomical analyses resulted in the identification of a colony of S. siderea from offshore northern Bahia state. Following recent studies, the occurrence of Caribbean siderastreids to western South Atlantic provides new criteria to assess intra- and interpopulational morphological variation of the endemic S. stellata, refuting historical trends of synonymizations possibly biased by long-term taxonomical misunderstandings. [ABSTRACT FROM AUTHOR]

The Indo-Pacific coral genus Psammocora Dana (1846) has never been formally revised, and its phylogeny has only been partially explored. Several synonymies have been proposed for the 11 nominal species which have highly plastic branching growth forms. In the present study, the definition of genetic and morphologic boundaries among three currently recognized branching morpho-species, Psammocora stellata, Psammocora contigua and Psammocora obtusangula, is addressed through a joint morphometric and molecular study using corallite and branch measurements, and a portion of the β-tubulin gene as a marker. The results show a morphological and partial phylogenetic distinction between P. stellata specimens and a complex composed of P. contigua and P. obtusangula, which is interpreted as a synonym species of P. contigua. Among the factors that could be responsible for the lack of reciprocal monophyly of the three species, hybridization is considered the most likely, due to the presence of interspecific recombinant sequences. Type material of nominal species of branching Psammocora is examined and classified based on genetically defined groups, and compared with synonym in the literature. Among the morphological characters used, corallite variables were best for discriminating between the two lineages and allow recognition of putative hybrid specimens. Psammocora stellata is reported for the first time in the western Indian Ocean (Mayotte), thus greatly extending its known distribution range. Finally, a hybrid swarm is identified in the Arabo-Persian Gulf, while no genetic structure is detected elsewhere in the Indo-Pacific region. [ABSTRACT FROM AUTHOR]

A comparative morphological and molecular characterization of species boundaries between four species of the Scleractinian genus Psammocora, namely P. digitata, P. haimeana, P. profundacella and P. contigua was conducted. The definition of species boundaries in this genus has been the subject of few studies, in spite of the presence of ambiguous taxonomic distinction, and a revision of the genus has never been undertaken. The multivariate analyses of both descriptive and morphometric characters confirmed the distinction of P. digitata and P. contigua, conversely P. haimeana, P. profundacella and their intermediate morph differentiated on the basis of descriptive morphologic characters only. Morphometric characters alone allowed a less defined distinction between morphs, and morphological boundaries essentially intergraded in a gradient driven by enclosed corallite series characters. The phylogenetic analysis of a portion of the rDNA confirmed the morphological inferences, as P. digitata appears to be a distinct evolutionary lineage. Conversely, the other four morphs, P. contigua, P. haimeana, P. profundacella and their intermediate constitute a polytomic gene pool significantly distinct from P. digitata. Yet, P. contigua is significantly distinct from the other three morphs. Both morphological and molecular approaches suggested that P. haimeana, P. profundacella and their intermediate cannot be considered clearly distinct entities. Hybridization with other species of this genus not included in this study, or recent origin may have contributed to the polyphyly and lack of phylogenetic resolution of P. haimeana, P. profundacella and their intermediate morph. They appear to constitute a single gene pool showing morphological characters encompassing a gradient from the P. haimeana to the P. profundacella morphs. Such morphological variability possibly depends on environmental factors such as light conditions. [ABSTRACT FROM AUTHOR]

Community metabolism and air-sea carbon dioxide (CO[sub2]) fluxes were investigated in July 1992 on a fringing reef at Moorea (French Polynesia). The benthic community was dominated by macroalgae (85% Substratum cover) and comprised of Phaeophyceae Padina tenuis (Bory), Turbinaria arnata (Turner). J. Agardth, and Hydrodatrus clathratus Bory (Howe); Chlorophyta Halimeda increassata fovata J. Agardth (Howe); and Ventricaria ventricosa J-Agardh (Olsen et West), as well as several Rhodophyta (Actinotichia fragilis Forskal (Bergesen) and several species of encrusting coralline algae). Algal biomass was 171 g dry weight-m[sup2]. Community gross production (P[subg]), respiration (R), and net calcification (G) were measured in an open-top enclosure. P[subg] and R were resectively 248 and 240 mmol CO[sub2] m[sup2]d[sup-1], and there was a slight net dissolution of CaCO[sub3] (0.8 mmol-m[sup2]d[sup-1]). This site was a sink for atmospheric CO[sub2] (10 ± 4 mmol CO[sub2]m[sup2]d[sup-1]), and he analysis of data from the literature suggests that this is a general feature of algal-dominated reefs. Measurement of air-sea CO[sub2] fluxes in open water close to the enclosure demonstrated that changes in small-scale hydrodynamics can lead to mislealding conclusions. Net CO[sub2] evasion to the atmosphere was measured on the fringing reef due to changes in the current pattern that drove water from the barrier reef (a CO[sub2] source) to the study site. [ABSTRACT FROM AUTHOR]

Mesophotic coral ecosystems in the Indo-Pacific remain relatively unexplored, particularly at lower mesophotic depths (≥60 m), despite their potentially large spatial extent. Here, we used a remotely operated vehicle to conduct a qualitative assessment of the zooxanthellate coral community at lower mesophotic depths (60–125 m) at 10 different locations in the Great Barrier Reef Marine Park and the Coral Sea Commonwealth Marine Reserve. Lower mesophotic coral communities were present at all 10 locations, with zooxanthellate scleractinian corals extending down to ~100 metres on walls and ~125 m on steep slopes. Lower mesophotic coral communities were most diverse in the 60–80 m zone, while at depths of ≥100 m the coral community consisted almost exclusively of the genus Leptoseris. Collections of coral specimens (n = 213) between 60 and 125 m depth confirmed the presence of at least 29 different species belonging to 18 genera, including several potential new species and geographic/depth range extensions. Overall, this study highlights that lower mesophotic coral ecosystems are likely to be ubiquitous features on the outer reefs of the Great Barrier Reef and atolls of the Coral Sea, and harbour a generic and species richness of corals that is much higher than thus far reported. Further research efforts are urgently required to better understand and manage these ecosystems as part of the Great Barrier Reef Marine Park and Coral Sea Commonwealth Marine Reserve. [ABSTRACT FROM AUTHOR]

Rapa (27°36′ S, 144°20′ W) is a small (~40 km2) volcanic island isolated in the Southern Austral Archipelago, where direct anthropogenic stressors are extremely limited. Here, we present the results of the first quantitative survey of coral community structure across habitats and depths around the island. Despite its geographical isolation in the depauperate South Central Pacific, its small size and unfavourable environmental conditions (competition with macroalgae, low sea surface temperatures, reduced reef accretion), the diversity of scleractinian corals at Rapa is particularly high (112 species from 32 genera, including 37 species of Acropora) in comparison to other French Polynesian islands and subtropical Pacific locations. Our results indicate that the abundance (>100 colonies per 10 m2 recorded at nine of the 17 sampling stations) and cover (>40% at four stations) of corals are relatively high for a marginal reef location. Strong spatial heterogeneity was found, with high variation in diversity, abundance, cover and community composition among stations. Variation in community composition was related to habitat types, with distinct assemblages among fringing reefs within bays, reef formations at bay entrances, and those on the submerged platform surrounding the island. On the platform, a depth gradient was detected, with generic richness, abundance and cover generally greater at deeper stations (18-20 m depth) compared with medium-depth (10-12 m) and shallow (1-3 m) stations. A gradient was also recorded along bays, with increasing coral diversity and abundance from the bay heads to the bay entrances. The coral community at Rapa was characterized by the presence of several taxa not found in other French Polynesian archipelagos and the rarity of others that are common and abundant in the Society and the Tuamotu islands. Another distinctive feature of reef communities at Rapa is the high cover and dominance of macroalgae, particularly in the shallower parts of the surrounding platform, which probably explains the lower densities of coral colonies recorded there. These characteristics of the diversity and biogeographical composition of coral assemblages at Rapa provide considerable ecological grounds for its conservation. [ABSTRACT FROM AUTHOR]

High-latitude coral reefs may be a refuge and area of reef expansion under climate change. As these locations are expected to become dryer and as livestock and agricultural yields decline, coastal populations may become increasingly dependent on marine resources. To evaluate this social--ecological conundrum, we examined the Grand Récif of Toliara (GRT), southwest Madagascar, which was intensively studied in the 1960s and has been highly degraded since the 1980s. We analyzed the social and ecological published and unpublished literature on this region and provide new data to assess the magnitude of the changes and evaluate the causes of reef degradation. Top-down controls were identified as the major drivers: human population growth and migrations, overfishing, and climate change, specifically decreased rainfall and rising temperature. Water quality has not changed since originally studied, and bottom-up control was ruled out. The identified network of social--ecological processes acting at different scales implies that decision makers will face complex problems that are linked to broader social, economic, and policy issues. This characterizes wicked problems, which are often dealt with by partial solutions that are exploratory and include inputs from various stakeholders along with information sharing, knowledge synthesis, and trust building. A hybrid approach based on classical fishery management options and preferences, along with monitoring, feedback and forums for searching solutions, could move the process of adaptation forward once an adaptive and appropriately scaled governance system is functioning. This approach has broad implications for resources management given the emerging climate change and multiple social and environmental stresses. [ABSTRACT FROM AUTHOR]

Until coral molecular phylogenies were published, the genus Plesiastrea was traditionally part of the family Faviidae and considered by several authors to be closely related to the genus Montastraea. However, genetic data has shown that Plesiastrea versipora, the genus type species, is evolutionarily distinct within the Robust clade of the Scleractinia and does not belong to the large clade grouping most representatives of the families Faviidae, including Montastraea, Mussidae, Merulinidae, Trachyphylliidae, and Pectiniidae. Instead, P. versipora is closely related to non reef-dwelling taxa currently ascribed to the Oculinidae (Cyathelia axillaris) and Caryophylliidae (Trochocyathus efateensis). However, no discussion on the morphologic features of P. versipora compared to other taxa has been published yet. Moreover, no information is available about the phylogenetic placement of Plesiastrea devantieri, the only other species in the genus. The phylogeny of both Plesiastrea species was addressed through molecular analyses (COI and rDNA) and morphological analysis. Morphological differences between the two species included number of septa, cycles of vertical structures in front of the septa and septal micromorphology. On the basis of these data and nuclear and mitochondrial markers, P. devantieri belongs to the Faviidae-Merulinidae-Pectiniidae-Trachyphylliidae clade (Clade XVII sensu Fukami et al., 2008) and is most closely related to Goniastrea aspera and G. palauensis. The type species of the genus Goniastrea, G. retiformis, however, is not closely related to either G. aspera and G. palauensis, or to P. devantieri. Taxonomic implications of these findings and morphologic affinities between the two species and closely related taxa are discussed [ABSTRACT FROM AUTHOR]

Marine protected areas (MPAs) have been highlighted as a means toward effective conservation of coral reefs. New strategies are required to more effectively select MPA locations and increase the pace of their implementation. Many criteria exist to design MPA networks, but generally, it is recommended that networks conserve a diversity of species selected for, among other attributes, their representativeness, rarity, or endemicity. Because knowledge of species’ spatial distribution remains scarce, efficient surrogates are urgently needed. We used five different levels of habitat maps and six spatial scales of analysis to identify under which circumstances habitat data used to design MPA networks for Wallis Island provided better representation of species than random choice alone. Protected-area site selections were derived from a rarity–complementarity algorithm. Habitat surrogacy was tested for commercial fish species, all fish species, commercially harvested invertebrates, corals, and algae species. Efficiency of habitat surrogacy varied by species group, type of habitat map, and spatial scale of analysis. Maps with the highest habitat thematic complexity provided better surrogates than simpler maps and were more robust to changes in spatial scales. Surrogates were most efficient for commercial fishes, corals, and algae but not for commercial invertebrates. Conversely, other measurements of species-habitat associations, such as richness congruence and composition similarities provided weak results. We provide, in part, a habitat-mapping methodology for designation of MPAs for Pacific Ocean islands that are characterized by habitat zonations similar to Wallis. Given the increasing availability and affordability of space-borne imagery to map habitats, our approach could appreciably facilitate and improve current approaches to coral reef conservation and enhance MPA implementation. [ABSTRACT FROM AUTHOR]

Abstract: The mainland of New Caledonia (“Grande Terre”) is surrounded by one of the largest continuous barrier reef system in the world. In order to study the development history and internal structure of this system, drilling operations have been carried out at two sites (Amédée and Kendec islets), located on the barrier reef tract extending from the south-west 33 to the north-west of New Caledonia. The extracted cores are 128.50 and 148.75 m in length respectively. Lithological and paleoecological descriptions, combined with Uranium / Thorium dating, magnetostratigraphy and nannofossil-based biostratigraphy allowed a reef evolutionary scheme to be drawn. As a result of the interplay between margin subsidence and sea-level changes, 11 reef units formed successively during interglacial episodes at high sea levels in both sites. Depending on the subsidence rate of the western shelf-margin, major building in New Caledonia appears to have started during the MIS 11 (400,000 yr) from shallow-water carbonate platform deposits older than 780,000 yr. Comparing development patterns between the New Caledonian barrier reef and the Australian Great Barrier Reef clearly indicates that both global climate and regional tectonic history have been the major controls on reef initiation and growth along both sides of the Coral Sea. Climatic conditions are likely to have not been optimal before the late Quaternary, probably resulting in luxuriant reef expansion only during the last 400,000 yr. [Copyright &y& Elsevier]

Experiments were performed on coral species containing clade A (Stylophora pistillata, Montipora aequituberculata) or clade C (Acropora sp., Pavona cactus) zooxanthellae. The photosynthetic efficiency (Fv/Fm) of the corals was first assessed during a short-term increase in temperature (from 27 °C to 29 °C, 32 °C, and 34 °C) and acute exposure to UV radiation (20.5 W m-2 UVA and 1.2 W m-2 UVB) alone or in combination. Increasing temperature to 34 °C significantly decreased the Fv/Fm in S. pistillata and M. aequituberculata. Increased UV radiation alone significantly decreased the Fv/Fm of all coral species, even at 27 °C. There was a combined effect of temperature and UV radiation, which reduced Fv/Fm in all corals by 25% to 40%. During a long-term exposure to UV radiation (17 days) the Fv/Fm was significantly reduced after 3 days' exposure in all species, which did not recover their initial values, even after 17 days. By this time, all corals had synthesized mycosporine-like amino acids (MAAs). The concentration and diversity of MAAs differed among species, being higher for corals containing clade A zooxanthellae. Prolonged exposure to UV radiation at the nonstressful temperature of 27 °C conferred protection against independent, thermally induced photoinhibition in all four species. [ABSTRACT FROM AUTHOR]