Academic literature on the topic 'Madrepora oculata'

Abstract. The potential influence of the cold-water corals (CWCs) Lophelia pertusa and Madrepora oculata on the dynamics of inorganic nutrient and total organic carbon (TOC) concentrations and the abundances of prokaryotes and viruses in bottom water was assessed in onboard incubation experiments. Ammonium, nitrite, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and TOC concentrations and N:P ratios were typically higher in incubation water with corals than in controls, whereas nitrate concentrations did not reveal a clear trend. Mucus release (normalized to coral surface) was estimated by the net increase rate of TOC concentrations and averaged 23 ± 6 mg C m−2 h−1 for L. pertusa and 21 ± 8 mg C m−2 h−1 for M. oculata. Prokaryotic and viral abundance and turnover rates were typically stimulated in incubation water with corals. This prokaryotic stimulation averaged 6.0 ± 3.0 × 109 cells m−2 h−1 for L. pertusa and 8.4 ± 2.9 ×109 cells m−2 h−1 for M. oculata, whereas the viral stimulation averaged 15.6 ± 12.7 × 109 particles m−2 h−1 for L. pertusa and 4.3 ± 0.4 × 109 particles m−2 h−1 M. oculata. Our data suggest that prokaryotes and viruses are released from corals and that nutrient and mucus release enhanced prokaryotic and viral production. The result of this stimulation could be a fuelling of bottom water in CWC reefs with nutrients and organic matter and consequently an enhancement of microbe-mediated processes.

Abstract. The potential influence of the cold-water corals (CWCs) Lophelia pertusa and Madrepora oculata on the dynamics of inorganic nutrient and total organic carbon (TOC) concentrations and the abundances of prokaryotes and viruses in bottom water was assessed in onboard incubation experiments. Ammonium, nitrite, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and TOC concentrations and N:P ratios were typically higher in incubation water with corals than in controls, whereas nitrate concentrations did not reveal a clear trend. Mucus release (normalized to coral surface) was estimated by the net increase rate of TOC concentrations and averaged 23 ± 6 mg C m−2 h−1 for L. pertusa and 21 ± 8 mg C m−2 h−1 for M. oculata. Prokaryotic and viral abundance and turnover rates were typically stimulated in incubation water with corals. This estimated prokaryotic stimulation averaged 6.0 ± 3.0 × 109 cells m−2 h−1 for L. pertusa and 8.4 ± 2.9 × 109 cells m−2 h−1 for M. oculata, whereas the estimated viral stimulation averaged 15.6 ± 12.7 × 109 particles m−2 h−1 for L. pertusa and 4.3 ± 0.4 × 109 particles m−2 h−1 M. oculata. Our data suggest that prokaryotes and viruses are released from corals and that nutrient and mucus release enhanced prokaryotic and viral production. The result of this stimulation could be a fuelling of bottom water in CWC reefs with nutrients and organic matter and consequently an enhancement of microbe-mediated processes.

Global environmental changes, including ocean acidification, have been identified as a major threat to scleractinian corals. General predictions are that ocean acidification will be detrimental to reef growth and that 40 to more than 80 per cent of present-day reefs will decline during the next 50 years. Cold-water corals (CWCs) are thought to be strongly affected by changes in ocean acidification owing to their distribution in deep and/or cold waters, which naturally exhibit a CaCO 3 saturation state lower than in shallow/warm waters. Calcification was measured in three species of Mediterranean cold-water scleractinian corals ( Lophelia pertusa , Madrepora oculata and Desmophyllum dianthus ) on-board research vessels and soon after collection. Incubations were performed in ambient sea water. The species M. oculata was additionally incubated in sea water reduced or enriched in CO 2. At ambient conditions, calcification rates ranged between −0.01 and 0.23% d −1 . Calcification rates of M. oculata under variable partial pressure of CO 2 (pCO 2 ) were the same for ambient and elevated pCO 2 (404 and 867 µatm) with 0.06 ± 0.06% d −1 , while calcification was 0.12 ± 0.06% d −1 when pCO 2 was reduced to its pre-industrial level (285 µatm). This suggests that present-day CWC calcification in the Mediterranean Sea has already drastically declined (by 50%) as a consequence of anthropogenic-induced ocean acidification.

A new deep water acrothoracican species, Weltneria acanthostoma sp. nov., has been discovered from the area of the Blue Ridge Seamount, South China Sea, at a depth of 534 m. A single female was found in a burrow in the scleractinian Madrepora oculata. This specimen is assigned to the genus Weltneria due to the possession of six pairs of cirri and two-joined caudal appendages. Weltneria acanthostoma differs from its congeners in the morphology of the slightly sinusoid opercular bars having hooked posterior processes and four or five curved, conspicuous, simple teeth, and by the absence of a calcareous formation of the attachment disk. The genus Weltneria exhibits a Tethyan relictual pattern in its geographical distribution. The diagnosis of Weltneria is based on symplesiomorphies and the genus may be a non-monophyletic taxon.

Recent ROV (Remotely Operated Vehicle) exploration and bottom sampling in the southern Adriatic Sea (Apulian and Montenegrin margins) resulted in the discovery of cnidarian-rich deep-sea habitats in the depth range of ca. 400-700 m. In particular, ROV inspection of Montenegrin canyons reveals the existence of megabenthic communities dominated by a variety of cnidarians, including scleractinians (Madrepora oculata, Lophelia pertusa, Dendrophyllia cornigera), antipatharians (Leiopathes glaberrima) and gorgonians (Callogorgia verticillata) as major habitat forming taxa, often in association with sponges and, subordinately, serpulids. All such cnidarians are new records for the southeastern side of the Adriatic Sea. Our investigation indicates that an almost continuous belt of patchy cold water coral sites occurs along the entire southwestern margin (Apulian), basically connecting the Adriatic populations with those inhabiting the Ionian margin (Santa Maria di Leuca coral province).

In the north-east Atlantic, the dominant reef-framework forming coral species, Lophelia pertusa and Madrepora oculata, form a symbiotic association with the polychaete worm Eunice norvegica. The polychaete–coral symbiosis was studied by visually observing and photographing live animals in aquaria over many months and using time-lapse video under infra-red lighting to record activity patterns. The polychaetes act as reef aggregating agents by joining coral colonies and enhancing the development of reef patches in deep water. The symbiosis was investigated using samples collected from a relatively shallow site in a Norwegian fjord and from a deeper open ocean site in the Porcupine Seabight. The potential functional roles of this symbiosis are considered. The reef aggregating behaviour of the polychaete symbiont allied with the ability of the coral host to anastomose its branches, the polychaete tubes and debris falling onto the reef structure will help to shift the balance between reef growth and (bio)erosion in favour of growth.

During surveys in the Galicia Bank (northeastern Atlantic) in the years 2010–2011 (INDEMARES project), 25 species of scleractinian corals corals were collected in a depth interval of 744–1764 m. Most interesting species are described and depicted. Additionally, species list and remarks are given for the 23 species dredged in the bank during the 1987 SEAMOUNT 1 expedition at 675–1125 m depth.From a literature review and new records from Galicia Bank given herein, 31 species of scleractinian corals are known from this seamount in a depth interval of 614–1764 m depth. Six are colonial and 25 solitary, with 17 occurring on hard bottoms and 14 on soft bottoms. Desmophyllum dianthus, Lophelia pertusa and Madrepora oculata are the most widely distributed species in both number of stations and depth range of specimens collected alive. Some species were recorded outside their previously known bathymetric ranges in the northeastern Atlantic. Javania pseudoalabastra is first documented for the Iberian Peninsula and Spanish faunas. Thrypticotrochus sp. is first collected from the Atlantic Ocean.

Les coraux d'eau froide, comme Lophelia pertusa et Madrepora oculata, forment de vastes récifs qui constituent des habitats pour diverses communautés biologiques. Ils sont particulièrement menacés par l'augmentation de la température, et les modèles prédisent que la température pourrait encore augmenter de 3 °C dans l'océan Atlantique avant 2100. Des travaux récents ont permis de caractériser l'écologie de ces coraux et de mettre en évidence une dégradation de leur état de santé en réponse à des températures plus basses ou plus élevées. Cependant, les mécanismes moléculaires sous-jacents de leur réponse thermique, à l’échelle de l'holobionte (le corail et son microbiome associé), sont encore mal connus. Comprendre la réponse des coraux d'eau froide au réchauffement des océans, via une approche intégrative est déterminante pour évaluer leur résilience aux futurs changements climatiques. L'objectif de cette thèse était tout d'abord de décrire la dynamique in situ des holobiontes L. pertusa et M. oculata dans un canyon du Golfe de Gascogne (Atlantique Nord-Est) afin de déterminer les différences potentielles entre les populations atlantiques et méditerranéennes au niveau de la croissance et du microbiome. La croissance linéaire moyenne mesurée pour L. pertusa était de 2,4 ± 1,6 mm par an. La mortalité et la casse totales chez M. oculata n’ont pas permis de caractériser la croissance. Parallèlement, la détermination de la communauté microbienne a montré que le microbiome de L. pertusa était différent entre les deux régions avec une grande variabilité à l’échelle du canyon, tandis que M. oculata présentait un microbiome stable dans les différentes régions et une forte association avec certaines bactéries. Deuxièmement, la reproduction de ces deux espèces en Méditerranée a également été étudiée afin de déterminer les différences saisonnières avec la population Atlantique. Les résultats suggèrent une ponte saisonnière de L. pertusa en automne/début de l'hiver, correspondant à la formation de panaches d'eau profonde induits par les tempêtes en Méditerranée, tandis que M. oculata présente une reproduction continue. Le deuxième objectif général était de déterminer la réponse de l'espèce la plus sensible, L. pertusa, aux changements de température à l’échelle de l'holobionte, en utilisant la mesure des paramètres physiologiques (survie, croissance, nutrition et expression des gènes) et la réponse du microbiome. Au cours d'une expérience de deux mois en aquarium, nous avons montré qu'à une augmentation de température de +3 et +5 °C, L. pertusa de l'océan Atlantique Nord-Est présentait une modification de son microbiome parallèlement à une mortalité importante. Une approche métagénomique révèle la présence de gènes marqueurs de facteurs de virulence suggérant que la mort des coraux est due à des infections par des bactéries pathogènes. Dans une seconde expérience, menée à plus long terme, nous avons montré que si une baisse de température de 4 °C n'affectait pas la physiologie et le microbiome de L. pertusa, une augmentation de température de 4 °C entraînait une mortalité massive. Cette mortalité semble être associée à un niveau élevé de stress chez le corail, comme l'atteste l’augmentation de plusieurs gènes liés aux réponses immunitaire, inflammatoire et antioxydante, à la mort cellulaire, à la réparation et l'entretien de l'ADN, mais aussi à la modification de la communauté bactérienne. Nos travaux ont montré que L. pertusa et M. oculata présentent des stratégies de vie distinctes, notamment en termes de croissance, microbiome et reproduction, avec des différences marquées entre les populations. Nos résultats d'expériences en aquarium suggèrent cependant que les L. pertusa de l'Atlantique Nord-Est est aussi sensible au réchauffement que ceux des autres populations et il semble que tous les L. pertusa, indépendamment de la région d'où ils proviennent, seront fortement affectés par une augmentation de +3 °C
Cold-water corals such as Lophelia pertusa and Madrepora oculata, two key reef-forming species distributed worldwide, form extensive reefs providing highly valuable habitats for diverse biological communities. They are particularly threatened by increasing temperature, as models predict that temperature would further increase by up to 3 °C in the Atlantic Ocean before the end of the century. Recent work has characterised the cold-water coral ecology and has shown degraded health status both in response to lower and increased temperatures in different scleractinian species. However, the underlying molecular mechanisms of their thermal response, including the response at the holobiont level (i.e. the coral host and its associated microbiome), is still poorly known. Understanding the response of cold-water corals to ocean warming using integrative approach is of paramount importance to evaluate their resilience to future water temperatures. The goal of this thesis was firstly to describe the in situ dynamics of the holobiont from L. pertusa and M. oculata in a canyon of the Bay of Biscay (NE Atlantic Ocean) to determine potential differences between Atlantic and Mediterranean populations at the growth and microbiome levels. The average polyp linear growth measured for L. pertusa was 2.4 ± 1.6 mm yr−1, which fall in the lower range compared to previous estimations. Mortality and breakage were total in M. oculata could not allow characterization of growth. Concurrently, the microbial community determination showed that L. pertusa microbiome was versatile between the two regions with high variability within canyons, while M. oculata exhibited stable microbiome across the different regions, with strong association with some bacteria. Secondly, the reproductive biology of those two species in the Mediterranean Sea was also investigated to determine potential seasonal differences with the Atlantic population. The gametogenic cycle suggests a seasonal spawning of L. pertusa in autumn to early winter, corresponding to the formation of storm-induced deep-sea water plumes, while M. oculata shows continuous reproduction, with reproductive features of a species less opportunistic than L. pertusa. The second general objective was to forecast the response of the most sensitive species, L. pertusa, to temperature changes by determining the underlying molecular mechanisms of its thermal response at the holobiont level, using measurement of physiological parameters (survival, growth, nutrition and gene expression) and microbiome response. During a two-months aquaria experiment, we showed that at a +3 and +5 °C temperature increase, L. pertusa from the NE Atlantic Ocean exhibited a modification of its microbiome concomitantly to a large mortality. A metagenomic approach reveals the presence of genes markers for virulence factors suggesting that the death of the corals was due to infections by pathogenic bacteria. In a second experiment, conducted on longer term, we showed that while a 4 °C lower temperature did not affect L. pertusa physiology and microbiome, a 4 °C increase in temperature led to massive mortality. This mortality seems to be associated to a high level of stress in the coral, as attested by the upregulation of number of genes related to immune, inflammatory and antioxidant responses, cell death and apoptosis, DNA repair and maintenance, but also the shift in coral bacterial community towards pathogens and opportunistic bacteria. Our work showed that although living in close association, L. pertusa and M. oculata exhibit distinct living strategies, including growth pattern, microbiome and reproductive biology, but also strong differences among populations. Our results from aquaria experiment suggest however that NE Atlantic L. pertusa are as sensitive to warming as other populations and it appears that all L. pertusa, independently of the region they come from will be strongly impacted by an increase of +3 °C

Swiftia Duchassaing & Michelotti, 1864, is often found sparse in the NE Atlantic Ocean and Mediterranean Sea. When the cruise MSM 16/3 “PHAETON” filmed the upper bathyal off Mauritania in 2010, the first dense populations dominated by Swiftia were discovered in the NE Atlantic Ocean, co-occurring with the framework-forming scleractinians Desmophyllum pertusum (Linnaeus, 1758) and Madrepora oculata Linnaeus, 1758. Remotely operated vehicle (ROV) video annotation from two canyons and two coral mounds considered Swiftia phaeton Sampaio, Beuck & Freiwald, 2022 presence, size class and abundance as well as substrate and geomorphology of the seafloor. Coral gardens definition included abundance and size of the species. Dense and very dense mono- and multispecific coral gardens dominated by S. phaeton were mapped between 20°24′N and 17°54′N in 470–640 m depth. The resilience of these coral gardens off Mauritania is mainly linked to the presence of hard substrate available to settle and to the exposition of currents rich in food. Still, these ecosystems are located inside a hydrocarbon exploration area off Mauritania and where fisheries occur since the 1960s. Sedimentation plumes caused by both activities can travel and impact on settlement, development, and survival of these populations. Hence, these vulnerable “oases” should be protected.