Coral Taxonomy Research Articles

Revisionary systematics of the endemic soft coral fauna (Octocorallia: Alcyonacea: Alcyoniina) of the Agulhas Bioregion, South Africa.

The Agulhas Bioregion of southern South Africa supports a unique octocoral fauna that is entirely endemic to the region. Recent molecular phylogenetic studies indicate that this endemism extends to deeper taxonomic levels than had previously been recognized, and that most of these endemic species belong to genera and families that are also endemic to South Africa. Here we revise the taxonomy of soft corals (subordinal group Alcyoniina) that were previously assigned to the cosmopolitan families Alcyoniidae, Nephtheidae and Nidaliidae, describing three new families endemic to South Africa, along with four new genera and four new species. We reassign the endemic genera Acrophytum, Pieterfaurea and Lampophyton to Acrophytidae n. fam, and describe a new species of Lampophyton, L. spinatum n. sp. The endemic species Protodendron bruuni is reassigned to a new, monotypic genus, Corymbophyton bruuni n. comb., and family, Corymbophytidae n. fam. The endemic genus Leptophyton is placed in a third new family, Leptophytidae n. fam., along with three new genera that are established for species previously assigned to Alcyonium: Circularius wilsoni n. comb., Porphyrophyton distinctum n. comb., and Tenerodus fallax n. comb. In addition, we describe new species of Leptophyton, L. fustis n. sp.; Tenerodus, T. pollex n. gen. n. sp.; and Alcyonium, A. dolium n. sp.; reassign Protodendron verseveldti to Tenerodus verseveldti n. comb.; and reassign the endemic genus Dimorphophyton to family Paralcyoniidae. Although molecular phylogenetic analyses unite Acrophytidae, Corymbophytidae and Leptophytidae within a well-supported monophyletic group, both morphological and molecular distinctions support maintaining them as three separate families. These revisions increase the number of endemic species of shallow-water soft corals known from the Agulhas Bioregion to 40, and the number of endemic genera to 13.

The actuopaleontological studies on Cuban scleractinians and coral reefs of half a century ago are not over

Gathering and studying a rich collection of fossil corals in Bulgaria led to the definition of various new taxa, but highlighted the gaps in our knowledge of fossil Scleractinia. I needed to learn from living corals. An actuopaleontological project with massive sampling of all phenotypes following coral life in depth in Cuba (1970–1973) showed extraordinary scleractinian variability and led to “heresy” regarding the conventional Caribbean taxonomy. Subsequent fundamental new knowledge challenged Scleractinia taxonomy and justified the results of the investigation of the Cuban corals, through continuing contributions to: holistic approach to scleractinian species; integrative character of coral taxonomy; new paleobiological perspectives and tasks for study; and the evolutionary benefits of hybridization for reef survival. Continuing research can be supported by: an 80% preserved collection; a scientific audiovisual documentary; a monograph in Russian, French, and soon Spanish; and a substantially and rarely preserved coral life and reef ecosystem.

Some Aspects on the Taxonomy and Identification of Corals.

Some Aspects on the Taxonomy and Identification of Corals.

A new sequence data set of SSU rRNA gene for Scleractinia and its phylogenetic and ecological applications.

Scleractinian corals (i.e. hard corals) play a fundamental role in building and maintaining coral reefs, one of the most diverse ecosystems on Earth. Nevertheless, their phylogenies remain largely unresolved and little is known about dispersal and survival of their planktonic larval phase. The small subunit ribosomal RNA (SSU rRNA) is a commonly used gene for DNA barcoding in several metazoans, and small variable regions of SSU rRNA are widely adopted as barcode marker to investigate marine plankton community structure worldwide. Here, we provide a large sequence data set of the complete SSU rRNA gene from 298 specimens, representing all known extant reef coral families and a total of 106 genera. The secondary structure was extremely conserved within the order with few exceptions due to insertions or deletions occurring in the variable regions. Remarkable differences in SSU rRNA length and base composition were detected between and within acroporids (Acropora, Montipora, Isopora and Alveopora) compared to other corals. The V4 and V9 regions seem to be promising barcode loci because variation at commonly used barcode primer binding sites was extremely low, while their levels of divergence allowed families and genera to be distinguished. Atime-calibrated phylogeny of Scleractinia is provided, and mutation rate heterogeneity is demonstrated across main lineages. The use of this data set as a valuable reference for investigating aspects of ecology, biology, molecular taxonomy and evolution of scleractinian corals is discussed.

Research activities by Japanese Society for Coral Taxonomy

Research activities by Japanese Society for Coral Taxonomy

Species delimitation in the coral genus Goniopora (Scleractinia, Poritidae) from the Saudi Arabian Red Sea

Variable skeletal morphology, genotype induced plasticity, and homoplasy of skeletal structures have presented major challenges for scleractinian coral taxonomy and systematics since the 18th century. Although the recent integration of genetic and micromorphological data is helping to clarify the taxonomic confusion within the order, phylogenetic relationships and species delimitation within most coral genera are still far from settled. In the present study, the species boundaries in the scleractinian coral genus Goniopora were investigated using 199 colonies from the Saudi Arabian Red Sea and sequencing of four molecular markers: the mitochondrial intergenic spacer between CytB and NAD2, the nuclear ribosomal ITS region, and two single-copy nuclear genes (ATPsβ and CalM). DNA sequence data were analyzed using a variety of methods and exploratory species-delimitation tools. The results were broadly congruent in identifying five distinct molecular lineages within the sequenced Goniopora samples: G. somaliensis/G. savignyi, G. djiboutiensis/G. lobata, G. stokesi, G. albiconus/G. tenuidens, and G. minor/G. gracilis. Although the traditional macromorphological characters used to identify these nine morphospecies were not able to discriminate the obtained molecular clades, informative micromorphological and microstructural features (such as the micro-ornamentation and the arrangement of the columella) were recovered among the five lineages. Moreover, unique in vivo morphologies were associated with the genetic-delimited lineages, further supporting the molecular findings. This study represents the first attempt to identify species boundaries within Goniopora using a combined morpho-molecular approach. The obtained data establish a basis for future taxonomic revision of the genus, which should include colonies across its entire geographical distribution in the Indo-Pacific.

Merging scleractinian genera: the overwhelming genetic similarity between solitary Desmophyllum and colonial Lophelia.

BackgroundIn recent years, several types of molecular markers and new microscale skeletal characters have shown potential as powerful tools for phylogenetic reconstructions and higher-level taxonomy of scleractinian corals. Nonetheless, discrimination of closely related taxa is still highly controversial in scleractinian coral research. Here we used newly sequenced complete mitochondrial genomes and 30 microsatellites to define the genetic divergence between two closely related azooxanthellate taxa of the family Caryophylliidae: solitary Desmophyllum dianthus and colonial Lophelia pertusa.ResultsIn the mitochondrial control region, an astonishing 99.8 % of nucleotides between L. pertusa and D. dianthus were identical. Variability of the mitochondrial genomes of the two species is represented by only 12 non-synonymous out of 19 total nucleotide substitutions. Microsatellite sequence (37 loci) analysis of L. pertusa and D. dianthus showed genetic similarity is about 97 %. Our results also indicated that L. pertusa and D. dianthus show high skeletal plasticity in corallum shape and similarity in skeletal ontogeny, micromorphological (septal and wall granulations) and microstructural characters (arrangement of rapid accretion deposits, thickening deposits).ConclusionsMolecularly and morphologically, the solitary Desmophyllum and the dendroid Lophelia appear to be significantly more similar to each other than other unambiguous coral genera analysed to date. This consequently leads to ascribe both taxa under the generic name Desmophyllum (priority by date of publication). Findings of this study demonstrate that coloniality may not be a robust taxonomic character in scleractinian corals.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0654-8) contains supplementary material, which is available to authorized users.

Contrasting light spectra constrain the macro and microstructures of scleractinian corals.

The morphological plasticity of scleractinian corals can be influenced by numerous factors in their natural environment. However, it is difficult to identify in situ the relative influence of a single biotic or abiotic factor, due to potential interactions between them. Light is considered as a major factor affecting coral skeleton morphology, due to their symbiotic relation with photosynthetic zooxanthellae. Nonetheless, most studies addressing the importance of light on coral morphological plasticity have focused on photosynthetically active radiation (PAR) intensity, with the effect of light spectra remaining largely unknown. The present study evaluated how different light spectra affect the skeleton macro- and microstructures in two coral species (Acropora formosa sensu Veron (2000) and Stylophora pistillata) maintained under controlled laboratory conditions. We tested the effect of three light treatments with the same PAR but with a distinct spectral emission: 1) T5 fluorescent lamps with blue emission; 2) Light Emitting Diodes (LED) with predominantly blue emission; and 3) Light Emitting Plasma (LEP) with full spectra emission. To exclude potential bias generated by genetic variability, the experiment was performed with clonal fragments for both species. After 6 months of experiment, it was possible to detect in coral fragments of both species exposed to different light spectra significant differences in morphometry (e.g., distance among corallites, corallite diameter, and theca thickness), as well as in the organization of their skeleton microstructure. The variability found in the skeleton macro- and microstructures of clonal organisms points to the potential pitfalls associated with the exclusive use of morphometry on coral taxonomy. Moreover, the identification of a single factor influencing the morphology of coral skeletons is relevant for coral aquaculture and can allow the optimization of reef restoration efforts.

Taxonomy and phylogenetic relationships of the coral genera Australomussa and Parascolymia (Scleractinia, Lobophylliidae)

Novel micromorphological characters in combination with molecular studies have led to an extensive revision of the taxonomy and systematics of scleractinian corals. In the present work, we investigate the macro- and micromorphology and the phylogenetic position of the genera Australomussa and Parascolymia, two monotypic genera ascribed to the family Lobophylliidae. The molecular phylogeny of both genera was addressed using three markers, the partial mitochondrial COI gene and the nuclear histone H3 and the ribosomal ITS region. Based on molecular data, Australomussa and Parascolymia belong to the Lobophylliidae and they cluster together with the genera Lobophyllia and Symphyllia within the same clade. While A. rowleyensis and P. vitiensis are closely related based on the three gene regions examined, their macro and micromorphology suggest that these species are distinct, differing in several characters, such as continuity and thickness of the costosepta, the number of septa, septal tooth height, spacing, and shape, and the distribution and shape of granules. Thus, we revise the taxonomic status of the genus Australomussa as a junior synonym of Parascolymia.

Taxonomic classification of the reef coral families Merulinidae, Montastraeidae, and Diploastraeidae (Cnidaria: Anthozoa: Scleractinia)

Modern coral taxonomy has begun to resolve many long-standing problems in traditional systematics stemming from its reliance on skeletal macromorphology. By integrating examinations of colony, corallite, and subcorallite morphology with the molecular sequence data that have proliferated in the last decade, many taxa spread across the scleractinian tree of life have been incorporated into a rigorous classification underpinned by greater phylogenetic understanding. This monograph focuses on one of the most challenging clades recovered to date – its disarray epitomized by the informal name ‘Bigmessidae’. This group of predominantly Indo-Pacific species previously comprised families Merulinidae, Faviidae, Pectiniidae, and Trachyphylliidae, but in a recent study these have been incorporated within Merulinidae. We studied 84 living merulinid species by examining morphological traits at three different scales of coral skeletal structure − macromorphology, micromorphology, and microstructure − to construct a morphological matrix comprising 44 characters. Data were analysed via maximum parsimony and also transformed onto a robust molecular phylogeny under the parsimony and maximum likelihood criteria. Comparisons amongst morphological character types suggest that although many characters at every scale are homoplastic, some to a greater extent than others, several can aid in distinguishing genus-level clades. Our resulting trees and character analyses form the basis of a revised classification that spans a total of 139 species contained within 24 genera. The tree topologies necessitate the synonymization of Barabattoia as Dipsastraea, and Phymastrea as Favites. Furthermore, Astrea and Coelastrea are resurrected, and one new genus, Paramontastraea Huang & Budd gen. nov., is described. All the genera in Merulinidae, along with the monotypic Montastraeidae and Diploastraeidae, are diagnosed based on the characters examined. The integrative classification system proposed here will form the framework for more accurate biodiversity estimates and guide the taxonomic placement of extinct species. © 2014 The Linnean Society of London

Taxonomic classification of the reef coral families Merulinidae, Montastraeidae, and Diploastraeidae (Cnidaria: Anthozoa: Scleractinia)

Modern coral taxonomy has begun to resolve many long-standing problems in traditional systematics stemming from its reliance on skeletal macromorphology. By integrating examinations of colony, corallite, and subcorallite morphology with the molecular sequence data that have proliferated in the last decade, many taxa spread across the scleractinian tree of life have been incorporated into a rigorous classification underpinned by greater phylogenetic understanding. This monograph focuses on one of the most challenging clades recovered to date – its disarray epitomized by the informal name ‘Bigmessidae’. This group of predominantly Indo-Pacific species previously comprised families Merulinidae, Faviidae, Pectiniidae, and Trachyphylliidae, but in a recent study these have been incorporated within Merulinidae. We studied 84 living merulinid species by examining morphological traits at three different scales of coral skeletal structure − macromorphology, micromorphology, and microstructure − to construct a morphological matrix comprising 44 characters. Data were analysed via maximum parsimony and also transformed onto a robust molecular phylogeny under the parsimony and maximum likelihood criteria. Comparisons amongst morphological character types suggest that although many characters at every scale are homoplastic, some to a greater extent than others, several can aid in distinguishing genus-level clades. Our resulting trees and character analyses form the basis of a revised classification that spans a total of 139 species contained within 24 genera. The tree topologies necessitate the synonymization of Barabattoia as Dipsastraea, and Phymastrea as Favites. Furthermore, Astrea and Coelastrea are resurrected, and one new genus, Paramontastraea Huang & Budd gen. nov., is described. All the genera in Merulinidae, along with the monotypic Montastraeidae and Diploastraeidae, are diagnosed based on the characters examined. The integrative classification system proposed here will form the framework for more accurate biodiversity estimates and guide the taxonomic placement of extinct species. © 2014 The Linnean Society of London

Overview of the taxonomy of zooxanthellate Scleractinia

Coral taxonomy has entered a historical phase where nomenclatorial uncertainty is rapidly increasing. The fundamental cause is mandatory adherence to historical monographs that lack essential information of all sorts, and also to type specimens, if they exist at all, that are commonly unrecognizable fragments or are uncharacteristic of the species they are believed to represent. Historical problems, including incorrect subsequent type species designations, also create uncertainty for many well-established genera. The advent of in situ studies in the 1970s revealed these issues; now molecular technology is again changing the taxonomic landscape. The competing methodologies involved must be seen in context if they are to avoid becoming an additional basis for continuing nomenclatorial instability. To prevent this happening, the International Commission on Zoological Nomenclature (ICZN) will need to focus on rules that consolidate well-established nomenclature and allow for the designation of new type specimens that are unambiguous, and which include both skeletal material and soft tissue for molecular study. Taxonomic and biogeographic findings have now become linked, with molecular methodologies providing the capacity to re-visit past taxonomic decisions, and to extend both taxonomy and biogeography into the realm of evolutionary theory. It is proposed that most species will ultimately be seen as operational taxonomic units that are human rather than natural constructs, which in consequence will always have fuzzy morphological, genetic, and distribution boundaries. The pathway ahead calls for the integration of morphological and molecular taxonomies, and for website delivery of information that crosses current discipline boundaries.

The evolutionary history of the order Antipatharia (Cnidaria: Anthozoa: Hexacorallia) as inferred from mitochondrial and nuclear DNA: implications for black coral taxonomy and systematics

Although black corals inhabit all the world's oceans, they have been relatively understudied as ∼185 of 247 species occur at depths > 50 m. Antipatharians have been included in several phylogenetic studies; however, sample sizes are small and taxonomic coverage minimal. Low levels of mitochondrial (mt) sequence divergence within Scleractinia and Octocorallia are assumed to apply to all anthozoans, although no formal study has been conducted on the order Antipatharia. To quantify genetic variation in the black coral mitogenome, we analysed DNA sequences of the two longest intergenic regions (IGRs) and cox3-cox1 for 26 of 41 genera, representing all families and subfamilies. We also quantified divergence at the intraspecific level using six mtIGRs and their flanking protein-coding genes and rRNA for 100+ colonies of Antipathes griggi. Utilizing sequence data from the two mtIGRs, cox3-cox1, as well as nuclear 18S and 28S, we constructed the first multi-locus phylogenies of the Antipatharia. Reconstructions revealed that species in the genus Stichopathes are split across two families, Sibopathes macrospina groups among North Atlantic Parantipathes (suggesting the actinopharynx and mesenteries were secondarily lost), and three families are polyphyletic. These and other results provide novel, independent insights into the evolutionary history of antipatharians and support placement of species into higher-level groupings based on microscopic skeletal features rather than gross colony morphology. An illustrated key to the seven currently recognized families is also provided. © 2013 The Linnean Society of London

Systematics of the coral genus Craterastrea (Cnidaria, Anthozoa, Scleractinia) and description of a new family through combined morphological and molecular analyses

The monotypic genus Craterastrea was assigned to the family Siderastreidae owing to the similarity of its septal micromorphology to that of Coscinaraea. Subsequently, it was synonymized with Leptoseris, family Agariciidae, based on corallum macromorphology. Since then, it has remained poorly studied and has been known only from a small number of specimens from relatively deep reef environments in the Red Sea and the Chagos archipelago, northern Indian Ocean. Access to museum collections enabled examination of type material and the recovery of coral skeletons from the Seychelles, Madagascar, and Mayotte, southern Indian Ocean. A recent survey in Mayotte allowed the in situ imaging of Craterastrea in shallow and turbid reef environments and sampling for molecular analyses. The molecular analyses were in agreement with the examination of micromorphology and microstructure of skeletons by revealing that Craterastrea levis, the only species in the genus, differs much from Leptoseris foliosa, with which it was synonymized. Moreover, Craterastrea is closely related to Coscinaraea, Horastrea and Anomastraea. However, these genera, currently ascribed to the Siderastreidae, are genetically distant to Siderastrea, the family's type genus, and Pseudosiderastrea. Hence, we restore the genus Craterastrea, describe the new family Coscinaraeidae due to its deep evolutionary divergence from the Siderastreidae, and provide revised diagnoses of the four genera in the family. The description of the new family Coscinaraeidae is a further step in the challenging but ongoing process of revision of the taxonomy of scleractinian corals as a result of the molecular systematics revolution.

Precious corals (Octocorallia: Coralliidae) from the northern West Pacific region with descriptions of two New Species

Members of the family Coralliidae, known as precious corals, are ecologically and economically important deep-sea or-ganisms. However, these organisms are currently threatened by commercial harvesting. In order to create and implementeffective conservative strategies, taxonomic knowledge of conservative targets is necessary, but unfortunately the taxon-omy of precious corals in this family is still ambiguous. This study provides a review of 15 Coralliidae species from thenorthern West Pacific region and a key to species identification. In addition, descriptions of two new species, Coralliumcarusrubrum n. sp. and C. taiwanicum n. sp., as well as a redescription of C. sulcatum Kishinouye, 1903 are included.Corallium carusrubrum n. sp. is distributed on seamounts off northeastern Taiwan. The autozooids of C. carusrubrum n.sp. are retractile and each can be fully withdrawn into the cortex thereby causing a mound on the surface which is shortand cylindrical rather than typically hemispherical; additionally, there are no long spindles in their tentacles. Coralliumtaiwanicum n. sp. is distributed in an area off southwestern Taiwan. It has special unique 8-radiates with an oval shapeand large projections. Corallium sulcatum is distributed from an area off southwestern Taiwan to western Japan. It hasbeen harvested and traded for decades, but there were no illustrations in its original description, hence a redescription of this species is provided.

Molecular phylogeny of the Robust clade (Faviidae, Mussidae, Merulinidae, and Pectiniidae): An Indian Ocean perspective

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.

Taxonomy and species boundaries in the coral genus Favia Milne Edwards and Haime, 1857 (Cnidaria: Scleractinia) from Thailand revealed by morphological and genetic data

While Faviidae is a widely and uniformly distributed coral family throughout the Indo-Pacific, the extensive phenotypic plasticity of colony surface and corallite features often confounds the use of macromorphological characters in species identification, and contributes to conflict between traditional classification and molecular analyses of the group. Recent advances in morphological and molecular techniques now provide a suite of methods to re-address coral taxonomy in complex groups, such as that represented by the Faviidae. This study combines morphologic measurements including “3D coordinates landmarks” data with phylogenetic assessments of nuclear (ITS) and mitochondrial (COI-trnM) DNA to assess species boundaries in nine species of Faviidae with para-septothecal walls from Thailand. Strong concordance was found between morphological features and a priori groupings based on both morphospecies and genetically defined groups (ITS and COI-trnM). Favia truncatus was the most well-defined species based on morphological analyses, and it was also shown to be monophyletic using phylogenetic analyses. Besides F. truncatus, the only other species that was found to be monophyletic in analyses of both genes was F. cf. helianthoides, but its skeletal morphology overlapped with the F. favus species complex (comprised of F. favus, F. speciosa, F. matthaii and F. rotumana). Although not genetically monophyletic, the F. favus species complex and F. pallida were fairly well delineated morphologically. Morphospecies within the F. favus species complex are therefore possibly a result of genetic drift and/or stable polymorphisms driven by divergent selection. These results represent a first step toward a taxonomic revision of the Indo-Pacific Favia, which will integrate morphological methods with the study of type material, genetic information, reproductive data, and tests of phenotypic plasticity—given that multiple lines of evidence are needed to resolve ambiguous species and assign species names.

Palaeobiological perspectives on variability and taxonomy of scleractinian corals

Scleractinians are well known for their exceptional variability and difficult taxonomy. Until the end of the nineteenth century, these corals were studied outside their natural habitat. In situ investigation brought to attention their variability and led to description of formae and attempts to depart from the typological taxonomy. Studies commenced in 1950s of extant scleractinians of Jamaica, the South Pacific, Madagascar, the Red Sea, Cuba, and Australia demonstrated instances of coralla unclassifiable in the described species because they possess intermediate characters, and sometimes one corallum exhibits the characteristics of more than one species. Since 1984, discoveries about scleractinian life history and molecular data further challenged the conventional taxonomy. The coral holobiont is now being studied as a totality of the coral animal, its endosymbiotic zooxanthellae, and its associated community of microorganisms. Molecular genetics and studies of life history combined with morphological variability and variability in geological time are needed for scleractinian taxonomy. The input of palaeontologists with temporal aspect as well as an enormous amount of morphological data is invaluable, as demonstrated by several examples based on detailed morphological observations later supported by molecular and life history information. Efforts to resolve the variability vs. taxonomy dilemma for fossil scleractinians would benefit from further actuopalaeontological work: studies at all levels of biological organization, including ancient DNA and evolutionary genetics, the rich fossil record, fractals and RLQ analysis, palaeopathological research, sclerochronology, the ecology and skeletogenesis of extant deep sea corals.

Coral biostromes of the Middle Jurassic from the Subbetic (Betic Cordillera, southern Spain): facies, coral taxonomy, taphonomy, and palaeoecology

Coral biostromes from the Camarena Formation (External Subbetic, Betic Cordillera) are reviewed under palaeoecologic, taphonomic, and palaeontologic aspects. The biostromes are dominated by phaceloid forms and are characterized by a typical shallow-marine microencruster assemblage with photophilic microencrusters and scarce microbial crusts. The abundance of stylinid corals and light-dependant microencrusters suggests oligotrophic conditions. Coral colonies were located among oolitic shoals that were unfavorable for coral growth. The corals were developed in phases without oolitic production alternating with phases of oolitic production, forming metric-scale sequences. A relative sea-level fall would have reduced the ooidal production and led to the deposition of thin layers of micritic facies in intertidal areas. The cementation and hardening of the bottom resulted in a hardground that was colonized by corals after a subsequent relative sea-level rise. The progressive increase of the energetic conditions induced an increasing production of ooids and the migration of oolitic shoals, which covered and finished the coral biostromes. Repetition of this process gave rise to sequences reflecting small pulses of oscillations in the relative sea level.

Changes of coral communities over 35 years: Integrating in situ and remote-sensing data on Saint-Leu Reef (la Réunion, Indian Ocean)

Monitoring coral reef communities at a decadal scale is necessary to understand and project their dynamics to provide a basis for reef management in light of disturbances and climate change. Complementing infrequent and localised in situ observations, time-series of aerial photographs and remotely sensed satellite images provide a means of monitoring the position and extent of reef-top coral communities, vegetation and abiotic substrata at the whole reef scale. The aim of the present study was to map such changes on Saint-Leu Reef (La Réunion) between 1973 and 2007. The period included two cyclones (1989, 2002) and one severe bleaching event (2002). Vertical images of the reef were recorded in five aerial photographs (1973, 1978, 1989, 1997, and 2003) and two Quickbird satellite images (2002, 2006) during that time. Quantitative in situ observations of parts of the reef-top were also available both to document ecological and substratum characteristics that produce the color and texture observable in the photos and satellite images. Coral communities were mapped on all images using manual delineation of polygons identified according to color and texture contrast. The 2006 Quickbird image was used as the mapping base and 15 types of coral communities were identified from a reef survey conducted in 2007. This hierarchical typology used coral growth forms, live and dead coral cover, macro-algae, substratum (sand, rubble and platform) and, to a lesser extent, coral taxonomy. The polygons at date t were over-laid onto image t − 1 across the whole series and their boundaries were manually edited to match the pattern on the earlier image. Labelling of polygons was guided by field-survey data and maps. For coral-dominated patches, six successive pairs of maps from 1973 to 2006 were compared to produce ‘coral community change maps’ for that period. Despite the multiple disturbance events, the coral community distribution and composition in 2006 on Saint-Leu Reef did not display major differences compared to 1973. This suggests a high degree of coral resilience at the site, led by rapid recovery of compact branching corals. The mapping techniques overcame challenges due to different image quality and the sparsity of in situ observations in time and space. Our results demonstrate the potential for further application of reef monitoring protocols based on complementary in situ and remote-sensing data to help understand the dynamics of reef-top coral reef communities and geomorphology over years to decades.