Azooxanthellate Corals Research Articles

Response of two temperate scleractinian corals to projected ocean warming and marine heatwaves.

The Mediterranean Sea is a hotspot of global change, particularly exposed to ocean warming and the increasing occurrence of marine heatwaves (MHWs). However, experiments based on long-term temperature data from the field are scarce. Here, we investigate the response of the zooxanthellate coral Cladocora caespitosa and the azooxanthellate coral Astroides calycularis to future warming and MHWs based on 8 years of in situ data. Corals were maintained in the laboratory for five months under four temperature conditions: Warming (3.2°C above the in situ mean from 2012 to 2020), Heatwave (temperatures of 2018 with two heatwaves), Ambient (in situ mean) and Cool (deeper water temperatures). Under the Warming treatment, some C. caespitosa colonies severely bleached and A. calycularis colonies presented necrosis. Cladocora caespitosa symbiosis was impaired by temperature with a decrease in the density of endosymbiotic algae and an increase in per cent whiteness in all the treatments except for the coolest. Recovery for both species was observed through different mechanisms such as regrowth of polyps of A. calycularis and recovery of pigmentation for C. caespitosa. These results suggest that A. calycularis and C. caespitosa may be resilient to heat stress and can recover from physiological stresses caused by heatwaves in the laboratory.

Diversity patterns of the South African azooxanthellate scleractinians (Cnidaria: Anthozoa), with considerations of environmental correlates.

Azooxanthellate scleractinian corals, a group of species that lack a symbiotic relationship with dinoflagellates, are influenced by environmental variables at various scales. As the global commitment to sustainably manage ocean ecosystems and resources rises, there is a growing need to describe biodiversity trends in previously unsampled areas. Benthic invertebrate research in South Africa is a developing field, and many taxa in deep water environments remain inadequately characterized. Recently, the South African azooxanthellate scleractinian fauna was taxonomically reviewed, but their distributional correlations with physical parameters have not been studied. Here we aim to understand the biodiversity gradients of the South African azooxanthellate coral fauna by analysing the environmental correlates of museum samples. The associated coordinate data were georeferenced and depth obtained from a national bathymetric dataset, prior to undertaking a multivariate analysis. This analysis encompassed several steps, including the grouping of the longitude and depth data (environmental data), identifying families characteristic of the group variability, and examining the correlation of the associated data with the biological data. Additionally, the analysis involved quantifying diversity patterns along the environmental gradients. Overall, our results confirmed two longitudinal groups (eastern margin [Group A] vs southern and western margin [Group B]) and 11 depth categories represented within two bathymetric zones (shallow [50-200 m] and deep [300-1000 m]). Caryophylliids, flabellids, and dendrophylliids contributed the most towards distinguishing longitudinal and depth gradients. Both abiotic variable (longitudinal and depth) partially explained coral distribution patterns, with depth being highly correlated to the species variation observed. Data limitations within our data set resulted to unexplained variance, however, despite these limitations, the study demonstrates that historical museum samples provide a valuable data source that can fill research sampling gaps and help improve the understanding of biodiversity patterns of the coral fauna in under sampled marine ecosystems.

Analytical improvements and assessment of long‐term performance of the oxidation–denitrifier method

The analysis of the nitrogen (N) isotopic composition of organic matter bound to fossil biomineral structures (BB‐δ15N) using the oxidation–denitrifier (O–D) method provides a novel tool to study past changes in N cycling processes.MethodsWe report a set of methodological improvements to the O–D method, including (a) a method for sealing the reaction vials in which the oxidation of organic N to NO3− takes place, (b) a recipe for bypassing the pH adjustment step before the bacterial conversion of NO3− to N2O, and (c) a method for storing recrystallized dipotassium peroxodisulfate (K2S2O8) under Ar atmosphere.ResultsThe new sealing method eliminates the occasional contamination and vial breakage that occurred previously while increasing sample throughput. The protocol for bypassing pH adjustment does not affect BB‐δ15N, and it significantly reduces the processing time. Storage of K2S2O8 reagent under Ar atmosphere produces stable oxidation blanks over more than 3.5 years. We report analytical blanks, accuracy, and precision for this methodology from eight users over the course of ~3.5 years of analyses at the Max Planck Institute for Chemistry. Our method produces analytical blanks characterized by low N content (0.30 ± 0.13 nmol N, 1σ, n = 195) and stable δ15N (−2.20 ± 3.13‰, n = 195). The analysis of reference amino acid standards USGS 40 and USGS 65 indicates an overall accuracy of −0.23 ± 0.35‰ (1σ, n = 891). The analysis of in‐house fossil standards gives similar analytical precision (1σ) across a range of BB‐δ15N values and biominerals: zooxanthellate coral standard PO‐1 (6.08 ± 0.21‰, n = 267), azooxanthellate coral standard LO‐1 (10.20 ± 0.28‰, n = 258), foraminifera standard MF‐1 (5.92 ± 0.28‰, n = 243), and tooth enamel AG‐Lox (4.06 ± 0.49‰, n = 78).ConclusionsThe methodological improvements significantly increase sample throughput without compromising analytical precision or accuracy down to 1 nmol of N.

Reproductive characteristics and gametogenic cycle of the scleractinian coral Dendrophyllia ramea.

The present study marks a pioneering investigation into the reproductive cycle of the scleractinian coral Dendrophyllia ramea. This is one of the first reproduction studies conducted in the Mediterranean Sea for a colonial azooxanthellate coral. Coral samples were collected in 2017 (May and October) and 2018 (February and July) in the Alborán Sea (SW Mediterranean). This location was selected due to its rarity as one of the few sites where this species thrives at depths shallower than 40 m. These samples were used to study the sexual patterns, fertilization mechanisms and gametogenic cycles by means of histological techniques. To broaden the scope, Sea Surface Temperature (SST) and Chlorophyll-a (Chl-a) data from open access databases have been considered to explore the potential influence of these environmental factors as triggers for gamete development and spawning time. The findings cast D. ramea as a gonochoric species, since no hermaphroditic specimens were observed among the analysed samples. Additionally, the lack of larvae and embryos in any of the analysed polyps, suggest that this species is fertilised externally. Two oocyte cohorts have been detected simultaneously, hinting at a yearly reproductive cycle, characterised by a prolonged oocyte maturation and seasonal spawning period taking place between August and October. Nevertheless, D. ramea display a low fecundity compared to other scleractinians inhabiting deep waters. Lastly, the early stages of gametogenesis seem to be coupled with the highest Chl-a values (i.e., March and December), whereas spawning takes place throughout the warmest period of the year (August to October).

Early life stages of a Mediterranean coral are vulnerable to ocean warming and acidification

Abstract. The ability of coral populations to recover from disturbance depends on larval dispersion and recruitment. While ocean warming and acidification effects on adult corals are well documented, information on early life stages is comparatively scarce. Here, we investigate whether ocean warming and acidification can affect the larval and recruit development of the Mediterranean azooxanthellate coral Astroides calycularis. Larvae and recruits were raised for 9 months at ambient (23 ∘C) and warm (26 ∘C) temperatures and ambient (8.0) and low pH (7.7, on the total scale). The timing of the larval metamorphosis, growth of the recruit polyp by linear extension and budding, and skeletal characteristics of the 9-month-old polyps were monitored. Settlement and metamorphosis were more successful and hastened under a warm temperature. In contrast, low pH delayed the metamorphosis and affected the growth of the recruits by reducing the calcified area of attachment to the substrate as well as by diminishing the skeleton volume and the number of septa. However, skeleton density was higher under low pH and ambient temperature. The warm temperature and low-pH treatment had a negative impact on the survival, settlement, and growth of recruits. This study provides evidence of the threat represented by ocean warming and acidification for the larval recruitment and the growth of recruits of A. calycularis.

A biogeographical assessment of deep-sea coral assemblages from coastwide visual surveys off California

During the period 1992–2014, we quantified 79,233 deep-sea corals (DSC; azooxanthellate corals occurring in cold or deep waters, generally >50 m) at depths 23–867 m from 1281 visual transects in areas of rocky substrata off northern, central, and southern California. DSC were present on 68% of transects at all depths and substrata types. Thirty-nine taxa and morphotypes from at least 19 families and 24 genera, including 20 species, were identified. Survey depths differed among study regions, overlapping between north and south at >575 m, and between central and south at <325 m. Within study regions, we examined taxa-specific depth and temperature ranges and quantified the spatial distribution of DSC densities. Across study regions, we interpreted species distributions in the context of the literature and biogeographic provinces off California, examined size distributions, and characterized assemblages relative to latitude and depth. We discovered depth range extensions for seven species, and provide the first taxa-specific in situ temperature data for the U.S. West Coast. Overall densities (number of colonies/100 m2) of DSC within study regions were 105.8 (north), 5.0 (central), and 7.3 (south), and highest densities occurred on mixed and hard substrata. We did not observe a change in density with depth. Density ‘hot’ spots (p < 0.05) were identified at multiple locations in the central and south regions for DSC (other than sea pens) and for sea pens, respectively. Despite survey depth differences, three species with large depth ranges were observed in all three study regions, and most species were observed in the biogeographical province(s) reported for them in the literature. Most DSC were ≤20 cm high and ≤10 cm wide; colonies >50 cm high and >40 cm wide were rare and found primarily in the south. Six DSC assemblages (p < 0.05) were identified. Mid-depth assemblages in the central and south differed considerably, while deep assemblages in the north and south were similar. A shallow assemblage comprised taxa shared by central and south regions. As the relative habitat value of DSC to fishes becomes more apparent, our results will provide invaluable information for the identification of essential fish habitat and priority areas in need of protection.

Living with an enemy: Invasive sun-coral (Tubastraea spp.) competing against sponges Desmapsamma anchorata in southeastern Brazil

The azooxanthellate corals Tubastraea coccinea and T. tagusensis invaded the Brazilian coast in the 1980s and is still in expansion, favored by lower predation and competition pressure in their new habitats. Interestingly, the native sponge Desmapsamma anchorata has been observed overgrowing these corals. Considering that competitive displacement is expected to play a major role in the successful outcome of an invasion, the present study tested the physical and chemical mechanisms possibly involved in the competition between D. anchorata and the Tubastraea corals through field and aquaria experiments as well as the Raman spectroscopy technique for chemical analysis. Our results showed that the sponge grew in all directions including over Tubastraea colonies and regardless of its presence. There was no evidence of a specific chemical response among sponges or corals. However, we observed the extrusion of mesenteric filaments and tentacles of corals and the projection of sponge tissue during interspecific interaction, which suggests that physical imposition plays a key role for space competition at micro scales. Given the interspersed nature of benthic species distributions and the fast expansion of Tubastraea, it is unlikely that D. anchorata or any other sponges could serve a biological control against these invasive corals at larger scales, but our results showed that at a microscale they can withstand the corals presence and even outgrow them locally.

Stress Resistance and Adaptation of the Aquatic Invasive Species Tubastraea Coccinea (Lesson, 1829) to Climate Change and Ocean Acidification

A great number of studies published on long-term ocean warming and increased acidification have forecasted changes in regional biodiversity preempted by aquatic invasive species (AIS). The present paper is focused on invasive Tubastraea coccinea (TC), an azooxanthellate AIS coral thriving in regions of the Gulf of Mexico, which has shown an ability to invade altered habitats, including endemic Indo-Pacific T. coccinea (TCP) populations. To determine if invasive TC are more stress resistant than endemic Indo-Pacific T. coccinea (TCP), authors measured tissue loss and heat shock protein 70 (HSP70) expression, using a full factorial design, post exposure to changes in pH (7.5 and 8.1) and heat stress (31 °C and 34 °C). Overall, the mean time required for TCP to reach 50% tissue loss (LD50) was less than observed for TC by a factor of 0.45 (p &lt; 0.0003). Increasing temperature was found to be a significant main effect (p = 0.004), decreasing the LD50 by a factor of 0.58. Increasing acidity to pH 7.5 from 8.1 did not change the sensitivity of TC to temperature; however, TCP displayed increased sensitivity at 31 °C. Increases in the relative density of HSP70 (TC) were seen at all treatment levels. Hence, TC appears more robust compared to TCP and may emerge as a new dominant coral displacing endemic populations as a consequence of climate change.

Occurrence of the supposedly endemic Australian azooxanthellate coral Astrangia woodsi Wells, 1955 in the eastern Arabian Sea

Occurrence of the supposedly endemic Australian azooxanthellate coral Astrangia woodsi Wells, 1955 in the eastern Arabian Sea

Azooxanthellate Scleractinia (Cnidaria, Anthozoa) from South Africa.

Globally, South Africa ranks in the top five countries regarding marine species richness per unit area. Given the high diversity, it is not surprising that many invertebrate taxa in the region are poorly characterised. The South African azooxanthellate Scleractinia (Anthozoa) is one such taxonomic group, and was last reviewed by Boshoff in 1980. Although more recent regional publications have reported on some species, there has not been a faunistic review that accounts for the country's species diversity since then. Moreover, numerous unidentified specimens representing more than three decades of sampling effort have accumulated. In this study the authors update the state of knowledge of South African azooxanthellate coral species. Specimens, particularly those within the extensive collections of the Iziko South African and Smithsonian museums, were morphologically examined and identified. Other data considered included historic data represented as imagery data, associated species data from recent research surveys, and the scientific literature. To date, the study has increased the total number of known species from 77 to 108 across eleven families, 28 new South African records, and three are new species with one new genus.

Combined effects of copper and microplastics on physiological parameters of Tubastrea aurea corals.

Microplastics (MPs) have been a serious environmental problem because it can carry pollution like heavy metals and organic pollutants. However, the combined effect of MPs and bivalent copper ion (Cu(II)) on the coral azooxanthellate has been rarely studied. In the present study, the combined effects of PVC and Cu(II) on the physiological responses of Tubastrea aurea were studied. Our results showed that MPs alone enhanced the activity of catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH). The mixture groups had the same effects on the CAT and GSH, which enhanced CAT and GSH activity by 97% and 53% respectively. MPs alone and the combined treatment groups decreased the activity of lipid peroxide (LPO) and the content of metallothionein (MT) by 45% and 20% of the coral Tubastrea aurea. Cu(II) exposure always had negative effect on the physiological parameters of coral, and MPs decreased the toxicity of Cu(II) in the combined groups. This work is the first time to report the combined effects of Cu(II) and microplastics on azooxanthellate coral, which will provide important preliminary data for the following research.

Two temperate corals are tolerant to low pH regardless of previous exposure to natural CO2 vents

AbstractOcean acidification is perceived to be a major threat for many calcifying organisms, including scleractinian corals. Here, we investigate (1) whether past exposure to low pH environments associated with CO2 vents could increase corals tolerance to low pH and (2) whether zooxanthellate corals are more tolerant to low pH than azooxanthellate corals. To test these hypotheses, two Mediterranean colonial corals Cladocora caespitosa (zooxanthellate) and Astroides calycularis (azooxanthellate) were collected from CO2 vents and reference sites and incubated in the laboratory under present day (pH on the total scale, pHT 8.07) and low pH conditions (pHT 7.70). Rates of net calcification, dark respiration, and photosynthesis were monitored during a 6‐month experiment. Monthly net calcification was assessed every 27–35 d using the buoyant weight technique, whereas light and dark net calcification was estimated using the alkalinity anomaly technique during 1‐h incubations. Neither species showed any change in net calcification rates, respiration, and photosynthesis regardless of their environmental history, pH treatment, and trophic strategy. Our results indicate that C. caespitosa and As. calycularis could tolerate future ocean acidification conditions for at least 6 months. These results will aid in predicting species' future responses to ocean acidification, and thus improve the management and conservation of Mediterranean corals.

A new species of the sun coral genus Tubastraea (Scleractinia: Dendrophylliidae) from Hong Kong.

Tubastraea, commonly known as sun coral, is a genus of brightly coloured azooxanthellate corals in the family Dendrophylliidae. The diversity of this genus is low, with only seven recognized species. Herein, we describe Tubastraea megacorallita sp. nov. from Hong Kong based on morphological and molecular analyses. This new species exhibits several characteristics of the genus including being colonial, having a rough texture of corallum and no epitheca. It can be distinguished from its congenerics by bigger corallites, and the Pourtals plan arrangement of its septa. The rDNA gene sequences (consisting of ITS1, 5.8S, ITS2, 18S and 28S) showed 2.455.18% divergence from those of its closest relatives, T. coccinea and T. micranthus.

Invasive Sun Coral Species Challenges Decommissioning of Structures Offshore Brazil

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 30656, “Decommissioning of Subsea Structures in Brazil: Effect of Invasive Species and Genome Sequence of the Azooxanthellate Coral Tubastraea sp.,” by João Humberto Guandalini Batista, SPE, Repsol; Mauro Rebelo, Universidade Federal do Rio de Janeiro; and Giordano Soares-Souza, SENAI CETIQT, prepared for the 2020 Offshore Technology Conference, originally scheduled to be held in Houston, 4–7 May. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. Decommissioning of offshore assets in Brazil is subject to high levels of uncertainty because of Tubastraea, an invasive species of sun coral. This species has a high capacity for dispersion and recruitment and has been associated with the replacement of native species in rocky shores, exerting a serious effect on native biodiversity. The complete paper explores the biology of the invasive species, aiming to identify methods to eliminate or diminish its spread. The authors write that data generated in this study will foster the development of effective technologies in coral-species management, whether species are invasive or threatened. Introduction Originally from the Coral Triangle in the Pacific Ocean—a highly diverse region with hundreds of coral species—Tubastraea was first observed in the Campos Basin in the 1980s. Tubastraea sp. have high fecundity and growth rates with the ability to reproduce asexually, establishing very dense populations. This fast reproduction allows larvae to outcompete native species in both natural and artificial substrates in the sea. Sun coral is extremely resistant to environmental change. It has been found in shallow waters, sometimes exposed to air, showing tolerance even to short periods of desiccation. Recently, new species have been identified in Brazilian waters, heightening concern over the proliferation of sun coral. In the past, the common understanding was that subspecies coccinea and tagusensis were those found in Brazilian waters. However, recent studies dedicated to the research of the Tubastraea genus raised suspicion of the presence of diaphana and aurea, with the possible occurrence of hybrids as well. The preference of Tubastraea is to live in structures that are static or mostly motionless, such as production platforms, subsea structures, and drilling rigs. This trait has made sun coral a major challenge for the local oil and gas industry. While in the Campos Basin, the main objective is to decrease dispersion of already bioencrusted production units and subsea structures, in the Santos Basin, the goal is to avoid colonization in structures in operation or those scheduled to be installed soon. To further complicate matters, drilling and intervention vessels and rigs are contracted to service both basins. They work in dynamic-positioning mode, stationary around the production units and subsea structures for lengths of time that exceed the reproduction cycle time of the sun coral, allowing larval dispersion.

The microbial profile of a tissue necrosis affecting the Atlantic invasive coral Tubastraea tagusensis

The Southwestern Atlantic rocky reef ecosystems are undergoing significant changes due to sun-corals (Tubastraea tagusensis and T. coccinea) invasion. At Búzios Island, on the northern coast of São Paulo State, where the abundance of T. tagusensis is particularly high, some colonies are displaying tissue necrosis, a phenomenon never reported for this invasive nor any other azooxanthellate coral species. Using next-generation sequencing, we sought to understand the relationship between T. tagusensis tissue necrosis and its microbiota. Thus, through amplicon sequencing, we studied both healthy and diseased coral colonies. Results indicate a wide variety of bacteria associated with healthy colonies and an even higher diversity associated with those corals presenting tissue necrosis, which displayed nearly 25% more microorganisms. Also, as the microbial community associated with the seven healthy colonies did not alter composition significantly, it was possible to verify the microbial succession during different stages of tissue necrosis (i.e., initial, intermediate, and advanced). Comparing the microbiome from healthy corals to those in early tissue necrosis suggests 21 potential pathogens, which might act as the promoters of such disease.

Occurrence of the azooxanthellate coral Phyllangia pequegnatae (Scleractinia: Caryophylliidae) in the Colombian Caribbean Sea: hidden diversity or another invasive species?

As part of a baseline biodiversity study of the marine fauna associated with the Marina of Puerto Velero (PVM) in the Colombian Caribbean, we record the presence of the azooxanthellate coral Phyllangia pequegnatae Cairns, 2000. This new record extends the geographic distribution of this species to the southwestern Caribbean and increases its bathymetric range to the shallow 0.3 m depth as this species was previously known between 48 and 112 m depth. The colony of P. pequegnatae consists of 15 corallites and it was collected from underneath one of the main docks (concrete). Images of live extended polyps and detailed corallite morphology illustrate the differences between the recorded species P. pequegnatae with respect to its congeneric Phyllangia americana americana Milne Edwards & Haime, 1849. We discussed two hypothetical scenarios for the occurrence of P. pequegnatae in the Colombian Caribbean: the expansion of the bathymetric range of a previously overlooked native species or its introduction via the fouling community of small vessels.

First record and range extension of the transversely-dividing azooxanthellate coral Truncatoflabellum mortenseni Cairns and Zibrowius, 1997 (Scleractinia, Flabellidae) in the Persian Gulf, Western Indo-Pacific Ocean

In the Persian Gulf, Azooxanthellate Scleractinia remain understudied compared to their symbiotic counterparts. Here, we report the presence of azooxanthellate coral Truncatoflabellum mortenseni (Cairns & Zibrowius, 1997) for the first time in Iranian deep waters. This species was found on soft sediments at depths of 83 and 101 m. Given this report, the distribution range of T. mortenseni, previously known to exist only in the Indonesian-Philippine regions, is now expanded to the Persian Gulf.

The earliest diverging extant scleractinian corals recovered by mitochondrial genomes

Evolutionary reconstructions of scleractinian corals have a discrepant proportion of zooxanthellate reef-building species in relation to their azooxanthellate deep-sea counterparts. In particular, the earliest diverging “Basal” lineage remains poorly studied compared to “Robust” and “Complex” corals. The lack of data from corals other than reef-building species impairs a broader understanding of scleractinian evolution. Here, based on complete mitogenomes, the early onset of azooxanthellate corals is explored focusing on one of the most morphologically distinct families, Micrabaciidae. Sequenced on both Illumina and Sanger platforms, mitogenomes of four micrabaciids range from 19,048 to 19,542 bp and have gene content and order similar to the majority of scleractinians. Phylogenies containing all mitochondrial genes confirm the monophyly of Micrabaciidae as a sister group to the rest of Scleractinia. This topology not only corroborates the hypothesis of a solitary and azooxanthellate ancestor for the order, but also agrees with the unique skeletal microstructure previously found in the family. Moreover, the early-diverging position of micrabaciids followed by gardineriids reinforces the previously observed macromorphological similarities between micrabaciids and Corallimorpharia as well as its microstructural differences with Gardineriidae. The fact that both families share features with family Kilbuchophylliidae ultimately points towards a Middle Ordovician origin for Scleractinia.

Marine litter and wood debris as habitat and vector for the range expansion of invasive corals (Tubastraea spp.)

Tubastraea coccinea Lesson, 1830 and T. tagusensis Wells 1982 are azooxanthellate corals non-native to Brazil and introduced through fouling on oil platforms, the primary vector. They first invaded the tropical rocky reefs at Ilha Grande Bay (southwest Atlantic Ocean), during the early 1990s. Currently, at some Brazilian locations these species occupy 80% of the benthos of the shallow subtidal. They cause economic and environmental impacts by fouling shipping and modifying native communities. This study provides observations of an additional mechanism of secondary dispersal by T. coccinea and T. tagusensis that were seen attached to floating wood debris and marine litter, which are highly abundant in the region. Such rafting corals have been found adjacent to invaded reefs and stranded on beaches. These observations indicate that transport by rafting over long distances may be another mechanism of range expansion and secondary introduction of these invasive species within the region.

Mesophotic azooxanthellate coral communities and submarine seascape during the early Pliocene in Manilva Basin (S Spain)

Azooxanthellate corals are the most abundant macrofossils in the lower Pliocene deposits of the Manilva Basin (S Spain). In this paper, the cnidarian fossil assemblages have been studied in order to reconstruct the original communities and to depict the seascapes. Benthic foraminiferal assemblages associated with the corals have also been analysed to infer the palaeoenvironmental conditions in which they developed. Two sections have been studied. In the Canuto section, Coenosmilia fecunda dominates the cnidarian assemblage, followed by Asterosmilia cf. prolifera and Asterosmilia sp., which are all preserved as moulds and casts. Benthic foraminiferal assemblages indicate oligotrophic conditions and deposition from the middle platform to the upper slope. The Alamos section is characterized by Madrepora oculata, Dendrophyllia ramea, Asterosmilia cf. prolifera, Asterosmilia sp., Coenosmilia fecunda, and gorgonians of the Isididae family (most likely Keratoisis melitensis and/or Lepidisis longiflora), as well as a basal holdfast attributed to a member of either Primnoidae or the Chrysogorgiidae family. Here, corals preserve their original skeletons. Benthic foraminifers suggest deposition in oligotrophic conditions in mid–outer platform settings. Corals in the Canuto section formed autochthonous fossil assemblages, while in the Alamos section they were slightly displaced from their original growth positions to form parautochthonous fossil concentrations. The cnidarian community in the Canuto section was characterized by low-tier organisms either attached to hard substrates provided by skeletal remains (Coenosmilia fecunda) or inhabiting fine-grained bottoms (Asterosmilia spp.). In the Alamos section, Coenosmilia fecunda and Asterosmilia spp. occupied the lowest tier levels. The gorgonians, isidids and members of the Primnoidae or Chrysogorgiidae families, colonized both soft and hard substrates, dominating the next tier level. Finally, Madrepora oculata and Dendrophyllia ramea settled on submarine cliffs or on large blocks derived from substrate, inhabiting the highest position in the community. Large specimens of gorgonians could have also occupied this position.