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1
Mayfield, Anderson B., et Alexandra C. Dempsey. « Environmentally-Driven Variation in the Physiology of a New Caledonian Reef Coral ». Oceans 3, no 1 (6 janvier 2022) : 15–29. http://dx.doi.org/10.3390/oceans3010002.
Texte intégralRésumé :
Given the widespread threats to coral reefs, scientists have lost the opportunity to understand the basic biology of “pristine” corals whose physiologies have not been markedly perturbed by human activity. For instance, high temperature-induced bleaching has been occurring annually since 2014 in New Caledonia. Because most corals cannot withstand repeated years when bleaching occurs, an analysis was undertaken to showcase coral behavior in a period just before the onset of “annual severe bleaching” (ASB; November 2013) such that future generations might know how these corals functioned in their last bleaching-free year. Pocillopora damicornis colonies were sampled across a variety of environmental gradients, and a subset was sampled during both day and night to understand how their molecular biology changes upon cessation of dinoflagellate photosynthesis. Of the 13 environmental parameters tested, sampling time (i.e., light) most significantly affected coral molecular physiology, and expression levels of a number of both host and Symbiodiniaceae genes demonstrated significant diel variation; endosymbiont mRNA expression was more temporally variable than that of their anthozoan hosts. Furthermore, expression of all stress-targeted genes in both eukaryotic compartments of the holobiont was high, even in isolated, uninhabited, federally protected atolls of the country’s far northwest. Whether this degree of sub-cellular stress reflects cumulative climate change impacts or, instead, a stress-hardened phenotype, will be unveiled through assessing the fates of these corals in the wake of increasingly frequent marine heatwaves.
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Blanckaert, Alice C. A., Tom Biscéré, Renaud Grover et Christine Ferrier-Pagès. « Species-Specific Response of Corals to Imbalanced Ratios of Inorganic Nutrients ». International Journal of Molecular Sciences 24, no 4 (4 février 2023) : 3119. http://dx.doi.org/10.3390/ijms24043119.
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Dissolved inorganic phosphorus (DIP) is a limiting nutrient in the physiology of scleractinian corals. Anthropogenic addition of dissolved inorganic nitrogen (DIN) to coastal reefs increases the seawater DIN:DIP ratio and further increases P limitation, which is detrimental to coral health. The effects of imbalanced DIN:DIP ratios on coral physiology require further investigation in coral species other than the most studied branching corals. Here we investigated the nutrient uptake rates, elemental tissue composition and physiology of a foliose stony coral, Turbinaria reniformis, and a soft coral, Sarcophyton glaucum, exposed to four different DIN: DIP ratios (0.5:0.2, 0.5:1, 3:0.2, 3:1). The results show that T. reniformis had high uptake rates of DIN and DIP, proportional to the seawater nutrient concentrations. DIN enrichment alone led to an increase in tissue N content, shifting the tissue N:P ratio towards P limitation. However, S. glaucum had 5 times lower uptake rates and only took up DIN when the seawater was simultaneously enriched with DIP. This double uptake of N and P did not alter tissue stoichiometry. This study allows us to better understand the susceptibility of corals to changes in the DIN:DIP ratio and predict how coral species will respond under eutrophic conditions in the reef.
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Huffmyer, Ariana S., Colton J. Johnson, Ashleigh M. Epps, Judith D. Lemus et Ruth D. Gates. « Feeding and thermal conditioning enhance coral temperature tolerance in juvenile Pocillopora acuta ». Royal Society Open Science 8, no 5 (mai 2021) : 210644. http://dx.doi.org/10.1098/rsos.210644.
Texte intégralRésumé :
Scleractinian corals form the foundation of coral reefs by acquiring autotrophic nutrition from photosynthetic endosymbionts (Symbiodiniaceae) and use feeding to obtain additional nutrition, especially when the symbiosis is compromised (i.e. bleaching). Juvenile corals are vulnerable to stress due to low energetic reserves and high demand for growth, which is compounded when additional stressors occur. Therefore, conditions that favour energy acquisition and storage may enhance survival under stressful conditions. To investigate the influence of feeding on thermal tolerance, we exposed Pocillopora acuta juveniles to temperature (ambient, 27.4°C versus cool, 25.9°C) and feeding treatments (fed versus unfed) for 30 days post-settlement and monitored growth and physiology, followed by tracking survival under thermal stress. Feeding increased growth and resulted in thicker tissues and elevated symbiont fluorescence. Under high-temperature stress (31–60 days post-settlement; ca 30.1°C), corals that were fed and previously exposed to cool temperature had 33% higher survival than other treatment groups. These corals demonstrated reduced symbiont fluorescence, which may have provided protective effects under thermal stress. These results highlight that the impacts of feeding on coral physiology and stress tolerance are dependent on temperature and as oceans continue to warm, early life stages may experience shifts in feeding strategies to survive.
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D'angelo, Cecilia, et Jörg Wiedenmann. « An experimental mesocosm for long-term studies of reef corals ». Journal of the Marine Biological Association of the United Kingdom 92, no 4 (9 décembre 2011) : 769–75. http://dx.doi.org/10.1017/s0025315411001883.
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Molecular biological methods including genomic and proteomic approaches hold a specific promise to provide new insights into the stress physiology of corals. However, to fully exploit the power of these techniques, aquarium setups are required that allow biological assays under tightly controlled laboratory conditions. Here, details are provided about the successful development of a closed coral mesocosm at the National Oceanography Centre, Southampton. The system can be operated without access to natural seawater and allows long-term observations and experimental studies of reef corals. The individual experimental tanks allow the corals to be exposed, for example, to different light and/or temperature conditions without the need to disconnect them from the system.
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Shahani, Kamran, Hong Song, Syed Raza Mehdi, Awakash Sharma, Ghulam Tunio, Junaidullah Qureshi, Noor Kalhoro et Nooruddin Khaskheli. « Design and Testing of an Underwater Microscope with Variable Objective Lens for the Study of Benthic Communities ». Journal of Marine Science and Application 20, no 1 (mars 2021) : 170–78. http://dx.doi.org/10.1007/s11804-020-00185-9.
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AbstractMonitoring the ecology and physiology of corals, sediments, planktons, and microplastic at a suitable spatial resolution is of great importance in oceanic scientific research. To meet this requirement, an underwater microscope with an electrically controlled variable lens was designed and tested. The captured microscopic images of corals, sediments, planktons, and microplastic revealed their physical, biological, and morphological characteristics. Further studies of the images also revealed the growth, degradation, and bleaching patterns of corals; the presence of plankton communities; and the types of microplastics. The imaging performance is majorly influenced by the choice of lenses, camera selection, and lighting method. Image dehazing, global saturation masks, and image histograms were used to extract the image features. Fundamental experimental proof was obtained with micro-scale images of corals, sediments, planktons, and microplastic at different magnifications. The designed underwater microscope can provide relevant new insights into the observation and detection of the future conditions of aquatic ecosystems.
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Bhagooli, Ranjeet, Mouneshwar Soondur, Sundy Ramah, Arvind Gopeechund, Sruti Jeetun et Deepeeka Kaullysing. « Photo-physiology of healthy and bleached corals from the Mascarene Plateau ». Western Indian Ocean Journal of Marine Science, no 2/2021 (20 juillet 2022) : 109–20. http://dx.doi.org/10.4314/wiojms.si2021.2.8.
Texte intégralRésumé :
This study presents the first report of variable photo-physiology of healthy-looking and bleached corals from the upper mesophotic waters of the Mascarene Plateau. In May 2018, during the FAO EAF-Nansen research expedition cruise, coral bleaching was visually observed. Five coral species from Saya de Malha Bank, namely Heliopora coerulea, Favites sp. and Porites sp. from 27 m and Acropora sp. and Lithophyllon repanda from 30 m, and three coral species from the Nazareth Bank, namely Acropora sp. and Galaxea fascicularis from 36 m and Stylophora-like species from 58 m were studied using the Video-Assisted Multi-Sampler (VAMS) and collected using a Van Veen grab. Chlorophyll a fluorescence parameters such as effective quantum yield at photosystem II (ΦPSII), relative maximum electron transport rate (rETRm), photosynthetic efficiency (α), photoinhibition (β), saturating light level (Ek), and maximum non-photochemical quenching (NPQm) were measured using a Diving-Pulse-Amplitude-Modulated (D-PAM) fluorometer to study variable photo-physiology in bleached and non-bleached corals. All photo-physiological parameters varied significantly among coral species tested and between coral conditions, except for β. The interaction between species and coral conditions was only significant in the case of β, but generally not significant. A two-way ANOVA indicated significant effects of depth and coral conditions in Acropora sp. on almost all photo-physiological parameters, except for β, and the effect of depth on rETRmax and α, and the effect of depth along with its interaction with coral conditions on Ek. ΦPSII did not differ in bleached and healthy-looking coral parts of Porites and Lithophyllon from 27 m, Galaxea and Acropora from 36 m while it decreased significantly in Heliopora and Favites at 27 m, Acropora from 30 m, and Stylophora-like at 58 m. NPQm did not change for Porites, Acropora (30 m) and Galaxea but it tended to increase for Heliopora, Acropora (36 m), Lithophyllon, Galaxea, and decrease for Favities, Acropora (30 m) and Stylophora-like. The thermally tolerant coral Porites exhibited normal photo-physiology even in bleached conditions while the bleached parts of Favites, Acropora (30 m) and Stylophora-like corals exhibited photo-physiological dysfunctioning. This study revealed that the seven studied corals from the upper mesophotic waters of the Mascarene Plateau are not spared from the bleaching phenomenon and exhibit variable photo-physiology in bleached and non-bleached conditions. Further studies are warranted to thoroughly understand the coral bleaching patterns and severity during summer periods at the Saya de Malha and Nazareth Banks.
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Rodolfo-Metalpa, R., S. Martin, C. Ferrier-Pagès et J. P. Gattuso. « Response of the temperate coral <i>Cladocora caespitosa</i> ; to mid- and long-term exposure to <i>p</i>CO<sub>2</sub> ; and temperature levels projected in 2100 ». Biogeosciences Discussions 6, no 4 (16 juillet 2009) : 7103–31. http://dx.doi.org/10.5194/bgd-6-7103-2009.
Texte intégralRésumé :
Abstract. Atmospheric CO2 partial pressure (pCO2) is expected to increase to 700 ppm or more by the end of the present century. Anthropogenic CO2 is absorbed by the oceans leading to decreases in pH and the CaCO3 saturation state (Ω) of the seawater. While pCO2 was shown to drastically decrease calcification rates in tropical, fast growing corals, here we show, using the Mediterranean symbiotic coral Cladocora caespitosa, that the conventional belief that an increase in pCO2, in the range predicted to 2100, reduces calcification rates may not be widespread in temperate corals. We found that the seasonal change in temperature was the predominant factor controlling the physiology and growth of C. caespitosa, while an increase in pCO2, alone or in combination with global warming, had no significant effect on photosynthesis, photosynthetic efficiency and calcification. This result differs from that obtained on reef-building corals, which exhibit lower rates of calcification at elevated pCO2. The lack of sensitivity of temperate corals to high-pCO2 levels might be due to its slow growth rates, which seem to be more dependent on temperature than on the saturation state of calcium carbonate in the range predicted for the end of the century.
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Gardner, Stephanie G., Daniel A. Nielsen, Olivier Laczka, Ronald Shimmon, Victor H. Beltran, Peter J. Ralph et Katherina Petrou. « Dimethylsulfoniopropionate, superoxide dismutase and glutathione as stress response indicators in three corals under short-term hyposalinity stress ». Proceedings of the Royal Society B : Biological Sciences 283, no 1824 (10 février 2016) : 20152418. http://dx.doi.org/10.1098/rspb.2015.2418.
Texte intégralRésumé :
Corals are among the most active producers of dimethylsulfoniopropionate (DMSP), a key molecule in marine sulfur cycling, yet the specific physiological role of DMSP in corals remains elusive. Here, we examine the oxidative stress response of three coral species ( Acropora millepora , Stylophora pistillata and Pocillopora damicornis ) and explore the antioxidant role of DMSP and its breakdown products under short-term hyposalinity stress. Symbiont photosynthetic activity declined with hyposalinity exposure in all three reef-building corals. This corresponded with the upregulation of superoxide dismutase and glutathione in the animal host of all three species. For the symbiont component, there were differences in antioxidant regulation, demonstrating differential responses to oxidative stress between the Symbiodinium subclades. Of the three coral species investigated, only A. millepora provided any evidence of the role of DMSP in the oxidative stress response. Our study reveals variability in antioxidant regulation in corals and highlights the influence life-history traits, and the subcladal differences can have on coral physiology. Our data expand on the emerging understanding of the role of DMSP in coral stress regulation and emphasizes the importance of exploring both the host and symbiont responses for defining the threshold of the coral holobiont to hyposalinity stress.
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Camp, Emma F., David J. Smith, Chris Evenhuis, Ian Enochs, Derek Manzello, Stephen Woodcock et David J. Suggett. « Acclimatization to high-variance habitats does not enhance physiological tolerance of two key Caribbean corals to future temperature and pH ». Proceedings of the Royal Society B : Biological Sciences 283, no 1831 (25 mai 2016) : 20160442. http://dx.doi.org/10.1098/rspb.2016.0442.
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Corals are acclimatized to populate dynamic habitats that neighbour coral reefs. Habitats such as seagrass beds exhibit broad diel changes in temperature and pH that routinely expose corals to conditions predicted for reefs over the next 50–100 years. However, whether such acclimatization effectively enhances physiological tolerance to, and hence provides refuge against, future climate scenarios remains unknown. Also, whether corals living in low-variance habitats can tolerate present-day high-variance conditions remains untested. We experimentally examined how pH and temperature predicted for the year 2100 affects the growth and physiology of two dominant Caribbean corals ( Acropora palmata and Porites astreoides ) native to habitats with intrinsically low (outer-reef terrace, LV) and/or high (neighbouring seagrass, HV) environmental variance. Under present-day temperature and pH, growth and metabolic rates (calcification, respiration and photosynthesis) were unchanged for HV versus LV populations. Superimposing future climate scenarios onto the HV and LV conditions did not result in any enhanced tolerance to colonies native to HV. Calcification rates were always lower for elevated temperature and/or reduced pH. Together, these results suggest that seagrass habitats may not serve as refugia against climate change if the magnitude of future temperature and pH changes is equivalent to neighbouring reef habitats.
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Gori, Andrea, Christine Ferrier-Pagès, Sebastian J. Hennige, Fiona Murray, Cécile Rottier, Laura C. Wicks et J. Murray Roberts. « Physiological response of the cold-water coralDesmophyllum dianthusto thermal stress and ocean acidification ». PeerJ 4 (2 février 2016) : e1606. http://dx.doi.org/10.7717/peerj.1606.
Texte intégralRésumé :
Rising temperatures and ocean acidification driven by anthropogenic carbon emissions threaten both tropical and temperate corals. However, the synergistic effect of these stressors on coral physiology is still poorly understood, in particular for cold-water corals. This study assessed changes in key physiological parameters (calcification, respiration and ammonium excretion) of the widespread cold-water coralDesmophyllum dianthusmaintained for ∼8 months at two temperatures (ambient 12 °C and elevated 15 °C) and two pCO2conditions (ambient 390 ppm and elevated 750 ppm). At ambient temperatures no change in instantaneous calcification, respiration or ammonium excretion rates was observed at either pCO2levels. Conversely, elevated temperature (15 °C) significantly reduced calcification rates, and combined elevated temperature and pCO2significantly reduced respiration rates. Changes in the ratio of respired oxygen to excreted nitrogen (O:N), which provides information on the main sources of energy being metabolized, indicated a shift from mixed use of protein and carbohydrate/lipid as metabolic substrates under control conditions, to less efficient protein-dominated catabolism under both stressors. Overall, this study shows that the physiology ofD. dianthusis more sensitive to thermal than pCO2stress, and that the predicted combination of rising temperatures and ocean acidification in the coming decades may severely impact this cold-water coral species.
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McIlroy, Shelby E., Philip D. Thompson, Felix Landry Yuan, Timothy C. Bonebrake et David M. Baker. « Subtropical thermal variation supports persistence of corals but limits productivity of coral reefs ». Proceedings of the Royal Society B : Biological Sciences 286, no 1907 (17 juillet 2019) : 20190882. http://dx.doi.org/10.1098/rspb.2019.0882.
Texte intégralRésumé :
Concomitant to the decline of tropical corals caused by increasing global sea temperatures is the potential removal of barriers to species range expansions into subtropical and temperate habitats. In these habitats, species must tolerate lower annual mean temperature, wider annual temperature ranges and lower minimum temperatures. To understand ecophysiological traits that will impact geographical range boundaries, we monitored populations of five coral species within a marginal habitat and used a year of in situ measures to model thermal performance of vital host, symbiont and holobiont physiology. Metabolic responses to temperature revealed two acclimatization strategies: peak productivity occurring at annual midpoint temperatures (4–6°C lower than tropical counterparts), or at annual maxima. Modelled relationships between temperature and P:R were compared to a year of daily subtropical sea temperatures and revealed that the relatively short time spent at any one temperature, limited optimal performance of all strategies to approximately half the days of the year. Thus, while subtropical corals can adjust their physiology to persist through seasonal lows, seasonal variation seems to be the key factor limiting coral productivity. This constraint on rapid reef accretion within subtropical environments provides insight into the global distribution of future coral reefs and their ecosystem services.
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Delgadillo-Ordoñez, Nathalia, Inês Raimundo, Adam R. Barno, Eslam O. Osman, Helena Villela, Morgan Bennett-Smith, Christian R. Voolstra, Francesca Benzoni et Raquel S. Peixoto. « Red Sea Atlas of Coral-Associated Bacteria Highlights Common Microbiome Members and Their Distribution across Environmental Gradients—A Systematic Review ». Microorganisms 10, no 12 (26 novembre 2022) : 2340. http://dx.doi.org/10.3390/microorganisms10122340.
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The Red Sea is a suitable model for studying coral reefs under climate change due to its strong environmental gradient that provides a window into future global warming scenarios. For instance, corals in the southern Red Sea thrive at temperatures predicted to occur at the end of the century in other biogeographic regions. Corals in the Red Sea thrive under contrasting thermal and environmental regimes along their latitudinal gradient. Because microbial communities associated with corals contribute to host physiology, we conducted a systematic review of the known diversity of Red Sea coral-associated bacteria, considering geographic location and host species. Our assessment comprises 54 studies of 67 coral host species employing cultivation-dependent and cultivation-independent techniques. Most studies have been conducted in the central and northern Red Sea, while the southern and western regions remain largely unexplored. Our data also show that, despite the high diversity of corals in the Red Sea, the most studied corals were Pocillopora verrucosa, Dipsastraea spp., Pleuractis granulosa, and Stylophora pistillata. Microbial diversity was dominated by bacteria from the class Gammaproteobacteria, while the most frequently occurring bacterial families included Rhodobacteraceae and Vibrionaceae. We also identified bacterial families exclusively associated with each of the studied coral orders: Scleractinia (n = 125), Alcyonacea (n = 7), and Capitata (n = 2). This review encompasses 20 years of research in the Red Sea, providing a baseline compendium for coral-associated bacterial diversity.
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Noble, J. P. A., et D. J. Lee. « Ontogenies and astogenies and their significance in some favositid and heliolitid corals ». Journal of Paleontology 64, no 4 (juillet 1990) : 515–23. http://dx.doi.org/10.1017/s0022336000042542.
Texte intégralRésumé :
The level of colony integration in tabulate corals is the degree of colony unity with respect to behavior, physiology, and development of individual organs or organ complexes within colonies. These are difficult to assess in fossils, but the level of colony integration can be tested by analyzing ontogenies and astogenies of two common Paleozoic tabulate coral groups, favositids and heliolitids. Favositids have been previously interpreted as highly integrated colonies, but results of the present examination suggest that the level of colony integration in favositids was rather lower than hitherto assumed. The ontogenies and astogenies in favositid colonies are not correlatable; thus, the significance of ontogenetic and astogenetic variations for systematic and phylogenetic resolution in favositids is difficult to assess at present. In contrast, astogenetic developmental sequences are recognized in heliolitids. Ontogenies in heliolitids were subordinated to the astogeny of the colony. This is closely related to the high degree of colony integration with respect to behavior and physiology of individual organs or organ complexes within colonies. Individual corallites were well linked and coordinated so that the whole colony could have functioned as a single individual. As a result, evolution in heliolitids operated at the colony level and by heterochronic (and other) modifications of astogenies rather than of ontogenies.
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Bellworthy, Jessica, et Maoz Fine. « Warming resistant corals from the Gulf of Aqaba live close to their cold-water bleaching threshold ». PeerJ 9 (25 mars 2021) : e11100. http://dx.doi.org/10.7717/peerj.11100.
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Global climate change is causing increasing variability and extremes in weather worldwide, a trend set to continue. In recent decades both anomalously warm and cold seawater temperatures have resulted in mass coral bleaching events. Whilst corals’ response to elevated temperature has justifiably attracted substantial research interest, coral physiology under cold water stress is relatively unfamiliar. The response to below typical winter water temperature was tested for two common reef building species from the Gulf of Aqaba in an ex situ experiment. Stylophora pistillata and Acropora eurystoma were exposed to 1 or 3 °C below average winter temperature and a suite of physiological parameters were assessed. At 3 °C below winter minima (ca. 18.6 °C), both species had significant declines in photosynthetic indices (maximum quantum yield, electron transport rate, saturation irradiance, and photochemical efficiency) and chlorophyll concentration compared to corals at ambient winter temperatures. It was previously unknown that corals at this site live close to their cold-water bleaching threshold and may be vulnerable as climate variability increases in magnitude. In order to determine if a cold winter reduces the known heat resistance of this population, the corals were subsequently exposed to an acute warm period at 30 °C the following summer. Exposed to above typical summer temperatures, both species showed fewer physiological deviations compared to the cold-water stress. Therefore, the cold winter experience did not increase corals’ susceptibility to above ambient summer temperatures. This study provides further support for the selection of heat tolerant genotypes colonising the Red Sea basin and thereby support the mechanism behind the Reef Refuge Hypothesis.
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Cornwall, Christopher E., Steeve Comeau, Hollie Putnam et Verena Schoepf. « Impacts of ocean warming and acidification on calcifying coral reef taxa : mechanisms responsible and adaptive capacity ». Emerging Topics in Life Sciences 6, no 1 (14 février 2022) : 1–9. http://dx.doi.org/10.1042/etls20210226.
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Ocean warming (OW) and acidification (OA) are two of the greatest global threats to the persistence of coral reefs. Calcifying reef taxa such as corals and coralline algae provide the essential substrate and habitat in tropical reefs but are at particular risk due to their susceptibility to both OW and OA. OW poses the greater threat to future reef growth and function, via its capacity to destabilise the productivity of both taxa, and to cause mass bleaching events and mortality of corals. Marine heatwaves are projected to increase in frequency, intensity, and duration over the coming decades, raising the question of whether coral reefs will be able to persist as functioning ecosystems and in what form. OA should not be overlooked, as its negative impacts on the calcification of reef-building corals and coralline algae will have consequences for global reef accretion. Given that OA can have negative impacts on the reproduction and early life stages of both coralline algae and corals, the interdependence of these taxa may result in negative feedbacks for reef replenishment. However, there is little evidence that OA causes coral bleaching or exacerbates the effects of OW on coral bleaching. Instead, there is some evidence that OA alters the photo-physiology of both taxa. Tropical coralline algal possess shorter generation times than corals, which could enable more rapid evolutionary responses. Future reefs will be dominated by taxa with shorter generation times and high plasticity, or those individuals inherently resistant and resilient to both marine heatwaves and OA.
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Tran, Cawa. « Coral–microbe interactions : their importance to reef function and survival ». Emerging Topics in Life Sciences 6, no 1 (4 février 2022) : 33–44. http://dx.doi.org/10.1042/etls20210229.
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Many different microorganisms associate with the coral host in a single entity known as the holobiont, and their interactions with the host contribute to coral health, thereby making them a fundamental part of reef function, survival, and conservation. As corals continue to be susceptible to bleaching due to environmental stress, coral-associated bacteria may have a potential role in alleviating bleaching. This review provides a synthesis of the various roles bacteria have in coral physiology and development, and explores the possibility that changes in the microbiome with environmental stress could have major implications in how corals acclimatize and survive. Recent studies on the interactions between the coral's algal and bacterial symbionts elucidate how bacteria may stabilize algal health and, therefore, mitigate bleaching. A summary of the innovative tools and experiments to examine host–microbe interactions in other cnidarians (a temperate coral, a jellyfish, two anemones, and a freshwater hydroid) is offered in this review to delineate our current knowledge of mechanisms underlying microbial establishment and maintenance in the animal host. A better understanding of these mechanisms may enhance the success of maintaining probiotics long-term in corals as a conservation strategy.
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Eyal, Gal, Itay Cohen, Lee Eyal-Shaham, Or Ben-Zvi, Yaron Tikochinski et Yossi Loya. « Photoacclimation and induction of light-enhanced calcification in the mesophotic coral Euphyllia paradivisa ». Royal Society Open Science 6, no 2 (février 2019) : 180527. http://dx.doi.org/10.1098/rsos.180527.
Texte intégralRésumé :
Corals and their photosymbionts experience inherent changes in light along depth gradients, leading them to have evolved several well-investigated photoacclimation strategies. As coral calcification is influenced by light (a process described as LEC—‘light-enhanced calcification’), studies have sought to determine the link between photosynthesis and calcification, but many puzzling aspects still persist. Here, we examine the physiology of Euphyllia paradivisa , a coral species found at a wide range of depths but that is strictly mesophotic in the Red Sea; and also examines the coupling between photosynthesis and LEC by investigating the response of the coral under several controlled light regimes during a long-term experiment. E. paradivisa specimens were collected from 40 to 50 m depth and incubated under three light conditions for a period of 1 year: full-spectrum shallow-water light (approx. 3 m, e.g. shallow-light treatment); blue deep-water light (approx. 40 m, e.g. mesophotic-light treatment) or total darkness (e.g. dark treatment). Net photosynthesis remained similar in the shallow-light-treated corals compared to the mesophotic-light-treated corals, under both low and high light. However, calcification increased dramatically with increasing light intensity in the shallow-light-treated corals, suggesting a decoupling between these processes. Photoacclimation to shallow-water conditions was indicated by enhanced respiration, a higher density of zooxanthellae per polyp and lower chlorophyll a content per cell. The dark-treated corals became completely bleached but did not lower their metabolism below that of the mesophotic-light-treated corals. No Symbiodinium clade shift was found following the year-long light treatments. We conclude that E. paradivisa , and its original symbiont clade, can adapt to various light conditions by controlling its metabolic rate and growth energy investment, and consequently induce LEC.
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Morikawa, Megan K., et Stephen R. Palumbi. « Using naturally occurring climate resilient corals to construct bleaching-resistant nurseries ». Proceedings of the National Academy of Sciences 116, no 21 (6 mai 2019) : 10586–91. http://dx.doi.org/10.1073/pnas.1721415116.
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Ecological restoration of forests, meadows, reefs, or other foundational ecosystems during climate change depends on the discovery and use of individuals able to withstand future conditions. For coral reefs, climate-tolerant corals might not remain tolerant in different environments because of widespread environmental adjustment of coral physiology and symbionts. Here, we test if parent corals retain their heat tolerance in nursery settings, if simple proxies predict successful colonies, and if heat-tolerant corals suffer lower growth or survival in normal settings. Before the 2015 natural bleaching event in American Samoa, we set out 800 coral fragments from 80 colonies of four species selected by prior tests to have a range of intraspecific natural heat tolerance. After the event, nursery stock from heat-tolerant parents showed two to three times less bleaching across species than nursery stock from less tolerant parents. They also retained higher individual genetic diversity through the bleaching event than did less heat-tolerant corals. The three best proxies for thermal tolerance were response to experimental heat stress, location on the reef, and thermal microclimate. Molecular biomarkers were also predictive but were highly species specific. Colony genotype and symbiont genus played a similarly strong role in predicting bleaching. Combined, our results show that selecting for host and symbiont resilience produced a multispecies coral nursery that withstood multiple bleaching events, that proxies for thermal tolerance in restoration can work across species and be inexpensive, and that different coral clones within species reacted very differently to bleaching.
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Ross, Claire L., Verena Schoepf, Thomas M. DeCarlo et Malcolm T. McCulloch. « Mechanisms and seasonal drivers of calcification in the temperate coral Turbinaria reniformis at its latitudinal limits ». Proceedings of the Royal Society B : Biological Sciences 285, no 1879 (23 mai 2018) : 20180215. http://dx.doi.org/10.1098/rspb.2018.0215.
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High-latitude coral reefs provide natural laboratories for investigating the mechanisms and limits of coral calcification. While the calcification processes of tropical corals have been studied intensively, little is known about how their temperate counterparts grow under much lower temperature and light conditions. Here, we report the results of a long-term (2-year) study of seasonal changes in calcification rates, photo-physiology and calcifying fluid (cf) chemistry (using boron isotope systematics and Raman spectroscopy) for the coral Turbinaria reniformis growing near its latitudinal limits (34.5° S) along the southern coast of Western Australia. In contrast with tropical corals, calcification rates were found to be threefold higher during winter (16 to 17° C) compared with summer (approx. 21° C), and negatively correlated with light, but lacking any correlation with temperature. These unexpected findings are attributed to a combination of higher chlorophyll a, and hence increased heterotrophy during winter compared with summer, together with the corals' ability to seasonally modulate pH cf , with carbonate ion concentration being the main controller of calcification rates. Conversely, calcium ion concentration [Ca 2+ ] cf declined with increasing calcification rates, resulting in aragonite saturation states Ω cf that were stable yet elevated fourfold above seawater values. Our results show that corals growing near their latitudinal limits exert strong physiological control over their cf in order to maintain year-round calcification rates that are insensitive to the unfavourable temperature regimes typical of high-latitude reefs.
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Pasaribu, Buntora, Noir Primadona Purba, Lantun Paradhita Dewanti, Daniel Pasaribu, Alexander Muhammad Akbar Khan, Syawaludin Alisyahbana Harahap, Mega Laksmini Syamsuddin et al. « Lipid Droplets in Endosymbiotic Symbiodiniaceae spp. Associated with Corals ». Plants 13, no 7 (25 mars 2024) : 949. http://dx.doi.org/10.3390/plants13070949.
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Symbiodiniaceae species is a dinoflagellate that plays a crucial role in maintaining the symbiotic mutualism of reef-building corals in the ocean. Reef-building corals, as hosts, provide the nutrition and habitat to endosymbiotic Symbiodiniaceae species and Symbiodiniaceae species transfer the fixed carbon to the corals for growth. Environmental stress is one of the factors impacting the physiology and metabolism of the corals-dinoflagellate association. The environmental stress triggers the metabolic changes in Symbiodiniaceae species resulting in an increase in the production of survival organelles related to storage components such as lipid droplets (LD). LDs are found as unique organelles, mainly composed of triacylglycerols surrounded by phospholipids embedded with some proteins. To date, it has been reported that investigation of lipid droplets significantly present in animals and plants led to the understanding that lipid droplets play a key role in lipid storage and transport. The major challenge of investigating endosymbiotic Symbiodiniaceae species lies in overcoming the strategies in isolating lesser lipid droplets present in its intercellular cells. Here, we review the most recent highlights of LD research in endosymbiotic Symbiodiniaceae species particularly focusing on LD biogenesis, mechanism, and major lipid droplet proteins. Moreover, to comprehend potential novel ways of energy storage in the symbiotic interaction between endosymbiotic Symbiodiniaceae species and its host, we also emphasize recent emerging environmental factors such as temperature, ocean acidification, and nutrient impacting the accumulation of lipid droplets in endosymbiotic Symbiodiniaceae species.
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Barott, Katie L., Megan E. Barron et Martin Tresguerres. « Identification of a molecular pH sensor in coral ». Proceedings of the Royal Society B : Biological Sciences 284, no 1866 (novembre 2017) : 20171769. http://dx.doi.org/10.1098/rspb.2017.1769.
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Maintaining stable intracellular pH (pHi) is essential for homeostasis, and requires the ability to both sense pH changes that may result from internal and external sources, and to regulate downstream compensatory pH pathways. Here we identified the cAMP-producing enzyme soluble adenylyl cyclase (sAC) as the first molecular pH sensor in corals. sAC protein was detected throughout coral tissues, including those involved in symbiosis and calcification. Application of a sAC-specific inhibitor caused significant and reversible pHi acidosis in isolated coral cells under both dark and light conditions, indicating sAC is essential for sensing and regulating pHi perturbations caused by respiration and photosynthesis. Furthermore, pHi regulation during external acidification was also dependent on sAC activity. Thus, sAC is a sensor and regulator of pH disturbances from both metabolic and external origin in corals. Since sAC is present in all coral cell types, and the cAMP pathway can regulate virtually every aspect of cell physiology through post-translational modifications of proteins, sAC is likely to trigger multiple homeostatic mechanisms in response to pH disturbances. This is also the first evidence that sAC modulates pHi in any non-mammalian animal. Since corals are basal metazoans, our results indicate this function is evolutionarily conserved across animals.
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Price, James T., Rowan H. McLachlan, Christopher P. Jury, Robert J. Toonen, Michael J. Wilkins et Andréa G. Grottoli. « Long-term coral microbial community acclimatization is associated with coral survival in a changing climate ». PLOS ONE 18, no 9 (22 septembre 2023) : e0291503. http://dx.doi.org/10.1371/journal.pone.0291503.
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The plasticity of some coral-associated microbial communities under stressors like warming and ocean acidification suggests the microbiome has a role in the acclimatization of corals to future ocean conditions. Here, we evaluated the acclimatization potential of coral-associated microbial communities of four Hawaiian coral species (Porites compressa, Porites lobata, Montipora capitata, and Pocillopora acuta) over 22-month mesocosm experiment. The corals were exposed to one of four treatments: control, ocean acidification, ocean warming, or combined future ocean conditions. Over the 22-month study, 33–67% of corals died or experienced a loss of most live tissue coverage in the ocean warming and future ocean treatments while only 0–10% died in the ocean acidification and control. Among the survivors, coral-associated microbial communities responded to the chronic future ocean treatment in one of two ways: (1) microbial communities differed between the control and future ocean treatment, suggesting the potential capacity for acclimatization, or (2) microbial communities did not significantly differ between the control and future ocean treatment. The first strategy was observed in both Porites species and was associated with higher survivorship compared to M. capitata and P. acuta which exhibited the second strategy. Interestingly, the microbial community responses to chronic stressors were independent of coral physiology. These findings indicate acclimatization of microbial communities may confer resilience in some species of corals to chronic warming associated with climate change. However, M. capitata genets that survived the future ocean treatment hosted significantly different microbial communities from those that died, suggesting the microbial communities of the survivors conferred some resilience. Thus, even among coral species with inflexible microbial communities, some individuals may already be tolerant to future ocean conditions. These findings suggest that coral-associated microbial communities could play an important role in the persistence of some corals and underlie climate change-driven shifts in coral community composition.
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Moynihan, Molly A., Shahrouz Amini, Nathalie F. Goodkin, Jani T. I. Tanzil, J. Q. Isaiah Chua, Gareth N. Fabbro, Tung-Yung Fan, Daniela N. Schmidt et Ali Miserez. « Environmental impact on the mechanical properties of Porites spp. corals ». Coral Reefs 40, no 3 (8 mars 2021) : 701–17. http://dx.doi.org/10.1007/s00338-021-02064-3.
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AbstractDespite the economic and ecological importance of corals’ skeletal structure, as well as their predicted vulnerability to future climate change, few studies have examined the skeletal mechanical properties at the nanoscale. As climate change is predicted to alter coral growth and physiology, as well as increase mechanical stress events (e.g., bioerosion, storm frequency), it is crucial to understand how skeletal mechanical properties change with environmental conditions. Moreover, while material properties are intimately linked to the chemical composition of the skeleton, no previous study has examined mechanical properties alongside carbonate geochemical composition. Using Porites coral cores from a wide range of reef environments (Thailand, Singapore, Taiwan), we correlated coral’s micro-mechanical properties with chemical composition. In contrast to previous mechanical measurements of reef-building corals, we document unprecedented variability in the hardness, stiffness, and micro-cracking stress of Porites corals across reef environments, which may significantly decrease the structural integrity of reef substrate. Corals from environments with low salinity and high sedimentation had higher organic content and fractured at lower loads, suggesting that skeletal organic content caused enhanced embrittlement. Within individual coral cores, we observed seasonal variability in skeletal stiffness, and a relationship between high sea surface temperature, increased stiffness, and high-density. Regionally, lower Sr/Ca and higher Mg/Ca coincided with decreased stiffness and hardness, which is likely driven by increased amorphous calcium carbonate and skeletal organic content. If the coral is significantly embrittled, as measured here in samples from Singapore, faster erosion is expected. A decrease in skeletal stiffness will decrease the quality of reef substrate, enhance the rate of bioerosion by predators and borers, and increase colony dislodgement, resulting in widespread loss of structural complexity.
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Sakai, Yusuke, Masayuki Hatta, Seishiro Furukawa, Masakado Kawata, Naoto Ueno et Shinichiro Maruyama. « Environmental factors explain spawning day deviation from full moon in the scleractinian coral Acropora ». Biology Letters 16, no 1 (janvier 2020) : 20190760. http://dx.doi.org/10.1098/rsbl.2019.0760.
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Broadcast-spawning scleractinian corals annually release their gametes with high levels of synchrony, both within and among species. However, the timing of spawning can vary inter-annually. In particular, the night of spawning relative to the full moon phase can vary considerably among years at some locations. Although multiple environmental factors can affect the night of spawning, their effects have not been quantitatively assessed at the multi-regional level. In this study, we analysed environmental factors that are potentially correlated with spawning day deviation, in relation to the full moon phase, in Acropora corals inhabiting seven reefs in Australia and Japan. We accordingly found that sea surface temperature and wind speed within one to two months prior to the full moon of the spawning month were strongly correlated with spawning day deviations. In addition, solar flux had a weak effect on the night of spawning. These findings indicate that Acropora have the capacity to adjust their development and physiology in response to environmental factors for fine-tuning the timing of synchronous spawning, thereby maximizing reproductive success and post-fertilization survival.
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Bellantuono, Anthony J., Ove Hoegh-Guldberg et Mauricio Rodriguez-Lanetty. « Resistance to thermal stress in corals without changes in symbiont composition ». Proceedings of the Royal Society B : Biological Sciences 279, no 1731 (5 octobre 2011) : 1100–1107. http://dx.doi.org/10.1098/rspb.2011.1780.
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Discovering how corals can adjust their thermal sensitivity in the context of global climate change is important in understanding the long-term persistence of coral reefs. In this study, we showed that short-term preconditioning to higher temperatures, 3°C below the experimentally determined bleaching threshold, for a period of 10 days provides thermal tolerance for the symbiosis stability between the scleractinian coral, Acropora millepora and Symbiodinium . Based on genotypic analysis, our results indicate that the acclimatization of this coral species to thermal stress does not come down to simple changes in Symbiodinium and/or the bacterial communities that associate with reef-building corals. This suggests that the physiological plasticity of the host and/or symbiotic components appears to play an important role in responding to ocean warming. The further study of host and symbiont physiology, both of Symbiodinium and prokaryotes, is of paramount importance in the context of global climate change, as mechanisms for rapid holobiont acclimatization will become increasingly important to the long-standing persistence of coral reefs.
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Baum, Gunilla, Indra Januar, Sebastian C. A. Ferse, Christian Wild et Andreas Kunzmann. « Abundance and physiology of dominant soft corals linked to water quality in Jakarta Bay, Indonesia ». PeerJ 4 (29 novembre 2016) : e2625. http://dx.doi.org/10.7717/peerj.2625.
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Declining water quality is one of the main reasons of coral reef degradation in the Thousand Islands off the megacity Jakarta, Indonesia. Shifts in benthic community composition to higher soft coral abundances have been reported for many degraded reefs throughout the Indo-Pacific. However, it is not clear to what extent soft coral abundance and physiology are influenced by water quality. In this study, live benthic cover and water quality (i.e. dissolved inorganic nutrients (DIN), turbidity (NTU), and sedimentation) were assessed at three sites (< 20 km north of Jakarta) in Jakarta Bay (JB) and five sites along the outer Thousand Islands (20–60 km north of Jakarta). This was supplemented by measurements of photosynthetic yield and, for the first time, respiratory electron transport system (ETS) activity of two dominant soft coral genera,Sarcophytonspp. andNephtheaspp. Findings revealed highly eutrophic water conditions in JB compared to the outer Thousand Islands, with 44% higher DIN load (7.65 μM/L), 67% higher NTU (1.49 NTU) and 47% higher sedimentation rate (30.4 g m−2d−1). Soft corals were the dominant type of coral cover within the bay (2.4% hard and 12.8% soft coral cover) compared to the outer Thousand Islands (28.3% hard and 6.9% soft coral cover). Soft coral abundances, photosynthetic yield, and ETS activity were highly correlated with key water quality parameters, particularly DIN and sedimentation rates. The findings suggest water quality controls the relative abundance and physiology of dominant soft corals in JB and may thus contribute to phase shifts from hard to soft coral dominance, highlighting the need to better manage water quality in order to prevent or reverse phase shifts.
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Lima, Laís F. O., Amanda T. Alker, Megan M. Morris, Robert A. Edwards, Samantha J. de Putron et Elizabeth A. Dinsdale. « Pre-Bleaching Coral Microbiome Is Enriched in Beneficial Taxa and Functions ». Microorganisms 12, no 5 (16 mai 2024) : 1005. http://dx.doi.org/10.3390/microorganisms12051005.
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Coral reef health is tightly connected to the coral holobiont, which is the association between the coral animal and a diverse microbiome functioning as a unit. The coral holobiont depends on key services such as nitrogen and sulfur cycling mediated by the associated bacteria. However, these microbial services may be impaired in response to environmental changes, such as thermal stress. A perturbed microbiome may lead to coral bleaching and disease outbreaks, which have caused an unprecedented loss in coral cover worldwide, particularly correlated to a warming ocean. The response mechanisms of the coral holobiont under high temperatures are not completely understood, but the associated microbial community is a potential source of acquired heat-tolerance. Here we investigate the effects of increased temperature on the taxonomic and functional profiles of coral surface mucous layer (SML) microbiomes in relationship to coral–algal physiology. We used shotgun metagenomics in an experimental setting to understand the dynamics of microbial taxa and genes in the SML microbiome of the coral Pseudodiploria strigosa under heat treatment. The metagenomes of corals exposed to heat showed high similarity at the level of bacterial genera and functional genes related to nitrogen and sulfur metabolism and stress response. The coral SML microbiome responded to heat with an increase in the relative abundance of taxa with probiotic potential, and functional genes for nitrogen and sulfur acquisition. Coral–algal physiology significantly explained the variation in the microbiome at taxonomic and functional levels. These consistent and specific microbial taxa and gene functions that significantly increased in proportional abundance in corals exposed to heat are potentially beneficial to coral health and thermal resistance.
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Wall, Christopher B., Mario Kaluhiokalani, Brian N. Popp, Megan J. Donahue et Ruth D. Gates. « Divergent symbiont communities determine the physiology and nutrition of a reef coral across a light-availability gradient ». ISME Journal 14, no 4 (3 janvier 2020) : 945–58. http://dx.doi.org/10.1038/s41396-019-0570-1.
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AbstractReef corals are mixotrophic organisms relying on symbiont-derived photoautotrophy and water column heterotrophy. Coral endosymbionts (Family: Symbiodiniaceae), while typically considered mutualists, display a range of species-specific and environmentally mediated opportunism in their interactions with coral hosts, potentially requiring corals to rely more on heterotrophy to avoid declines in performance. To test the influence of symbiont communities on coral physiology (tissue biomass, symbiont density, photopigmentation) and nutrition (δ13C, δ15N), we sampled Montipora capitata colonies dominated by a specialist symbiont Cladocopium spp. or a putative opportunist Durusdinium glynnii (hereafter, C- or D-colonies) from Kāne‘ohe Bay, Hawai‘i, across gradients in photosynthetically active radiation (PAR) during summer and winter. We report for the first time that isotope values of reef corals are influenced by Symbiodiniaceae communities, indicative of different autotrophic capacities among symbiont species. D-colonies had on average 56% higher symbiont densities, but lower photopigments per symbiont cell and consistently lower δ13C values in host and symbiont tissues; this pattern in isotope values is consistent with lower symbiont carbon assimilation and translocation to the host. Neither C- nor D-colonies showed signs of greater heterotrophy or nutritional plasticity; instead changes in δ13C values were driven by PAR availability and photoacclimation attributes that differed between symbiont communities. Together, these results reveal Symbiodiniaceae functional diversity produces distinct holobionts with different capacities for autotrophic nutrition, and energy tradeoffs from associating with opportunist symbionts are not met with increased heterotrophy.
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Dobson, Kerri L., Christine Ferrier-Pagès, Casey M. Saup et Andréa G. Grottoli. « The Effects of Temperature, Light, and Feeding on the Physiology of Pocillopora damicornis, Stylophora pistillata, and Turbinaria reniformis Corals ». Water 13, no 15 (27 juillet 2021) : 2048. http://dx.doi.org/10.3390/w13152048.
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Evidence has shown that individually feeding or reduced light can mitigate the negative effects of elevated temperature on coral physiology. We aimed to evaluate if simultaneous low light and feeding would mitigate, minimize, or exacerbate negative effects of elevated temperature on coral physiology and carbon budgets. Pocillopora damicornis, Stylophora pistillata, and Turbinaria reniformis were grown for 28 days under a fully factorial experiment including two seawater temperatures (ambient temperature of 25 °C, elevated temperature of 30 °C), two light levels (high light of 300 μmol photons m−2 s−1, low light of 150 μmol photons m−2 s−1), and either fed (Artemia nauplii) or unfed. Coral physiology was significantly affected by temperature in all species, but the way in which low light and feeding altered their physiological responses was species-specific. All three species photo-acclimated to low light by increasing chlorophyll a. Pocillopora damicornis required feeding to meet metabolic demand irrespective of temperature but was unable to maintain calcification under low light when fed. In T. reniformis, low light mitigated the negative effect of elevated temperature on total lipids, while feeding mitigated the negative effects of elevated temperature on metabolic demand. In S. pistillata, low light compounded the negative effects of elevated temperature on metabolic demand, while feeding minimized this negative effect but was not sufficient to provide 100% metabolic demand. Overall, low light and feeding did not act synergistically, nor additively, to mitigate the negative effects of elevated temperature on P. damicornis, S. pistillata, or T. reniformis. However, feeding alone was critical to the maintenance of metabolic demand at elevated temperature, suggesting that sufficient supply of heterotrophic food sources is likely essential for corals during thermal stress (bleaching) events.
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Twan, Wen-Hung, Jiang-Shiou Hwang, Yan-Horn Lee, Hua-Fang Wu, Ying-Hsiu Tung et Ching-Fong Chang. « Hormones and reproduction in scleractinian corals ». Comparative Biochemistry and Physiology Part A : Molecular & ; Integrative Physiology 144, no 3 (juillet 2006) : 247–53. http://dx.doi.org/10.1016/j.cbpa.2006.01.011.
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Godoy-Vitorino, Filipa, Claudia P. Ruiz-Diaz, Abigail Rivera-Seda, Juan S. Ramírez-Lugo et Carlos Toledo-Hernández. « The microbial biosphere of the coral Acropora cervicornis in Northeastern Puerto Rico ». PeerJ 5 (29 août 2017) : e3717. http://dx.doi.org/10.7717/peerj.3717.
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Background Coral reefs are the most biodiverse ecosystems in the marine realm, and they not only contribute a plethora of ecosystem services to other marine organisms, but they also are beneficial to humankind via, for instance, their role as nurseries for commercially important fish species. Corals are considered holobionts (host + symbionts) since they are composed not only of coral polyps, but also algae, other microbial eukaryotes and prokaryotes. In recent years, Caribbean reef corals, including the once-common scleractinian coral Acropora cervicornis, have suffered unprecedented mortality due to climate change-related stressors. Unfortunately, our basic knowledge of the molecular ecophysiology of reef corals, particularly with respect to their complex bacterial microbiota, is currently too poor to project how climate change will affect this species. For instance, we do not know how light influences microbial communities of A. cervicornis, arguably the most endangered of all Caribbean coral species. To this end, we characterized the microbiota of A. cervicornis inhabiting water depths with different light regimes. Methods Six A. cervicornis fragments from different individuals were collected at two different depths (three at 1.5 m and three at 11 m) from a reef 3.2 km off the northeastern coast of Puerto Rico. We characterized the microbial communities by sequencing the 16S rRNA gene region V4 with the Illumina platform. Results A total of 173,137 good-quality sequences were binned into 803 OTUs with a 97% similarity. We uncovered eight bacterial phyla at both depths with a dominance of 725 Rickettsiales OTUs (Proteobacteria). A fewer number (38) of low dominance OTUs varied by depth and taxa enriched in shallow water corals included Proteobacteria (e.g. Rhodobacteraceae and Serratia) and Firmicutes (Streptococcus). Those enriched in deeper water corals featured different Proteobacterial taxa (Campylobacterales and Bradyrhizobium) and Firmicutes (Lactobacillus). Discussion Our results confirm that the microbiota of A. cervicornis inhabiting the northeastern region of Puerto Rico is dominated by a Rickettsiales-like bacterium and that there are significant changes in less dominant taxa at different water depths. These changes in less dominant taxa may potentially impact the coral’s physiology, particularly with respect to its ability to respond to future increases in temperature and CO2.
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Lin, Chiahsin. « International Symposium on New Frontiers in Reef Coral Biotechnology (5 May 2022, Taiwan) ». Applied Sciences 12, no 11 (6 juin 2022) : 5758. http://dx.doi.org/10.3390/app12115758.
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Given the global threats towards coral reefs, this conference’s central theme, “Reef coral biotechnology”, is particularly timely. Our goal is to promote communication and dialogue in this field among marine researchers within and outside of Taiwan, and we have invited experts in the fields of coral reef ecology, physiology, conservation, and biotechnology to discuss their recent findings with a cadre of both local and foreign scientists, as well as students (undergraduate, Master’s, and Ph.D. students). We envision that these presentations will segue into discussions and collaborations that stimulate innovation in reef coral biotechnology, and particularly in the development of tools and approaches that improve the odds of conserving coral reefs and biopreserving reef corals.
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Phillips, K. « FED UP CORALS ». Journal of Experimental Biology 207, no 9 (1 avril 2004) : ii. http://dx.doi.org/10.1242/jeb.00961.
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Hegazi, Nesrine M., Tarik A. Mohamed, Hamada H. Saad, Montaser A. Al-Hammady, Taha A. Hussien, Mohamed-Elamir F. Hegazy et Harald Gross. « Molecular Network Guided Cataloging of the Secondary Metabolome of Selected Egyptian Red Sea Soft Corals ». Marine Drugs 20, no 10 (1 octobre 2022) : 630. http://dx.doi.org/10.3390/md20100630.
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Soft corals are recognized as an abundant source of diverse secondary metabolites with unique chemical features and physiologic capabilities. However, the discovery of these metabolites is usually hindered by the traditional protocol which requires a large quantity of living tissue for isolation and spectroscopic investigations. In order to overcome this problem, untargeted metabolomics protocols have been developed. The latter have been applied here to study the chemodiversity of common Egyptian soft coral species, using only minute amounts of coral biomass. Spectral similarity networks, based on high-resolution tandem mass spectrometry data, were employed to explore and highlight the metabolic biodiversity of nine Egyptian soft coral species. Species-specific metabolites were highlighted for future prioritization of soft coral species for MS-guided chemical investigation. Overall, 79 metabolites were tentatively assigned, encompassing diterpenes, sesquiterpenes, and sterols. Simultaneously, the methodology assisted in shedding light on newly-overlooked chemical diversity with potential undescribed scaffolds. For instance, glycosylated fatty acids, nitrogenated aromatic compounds, and polyketides were proposed in Sinularia leptoclados, while alkaloidal terpenes and N-acyl amino acids were proposed in both Sarcophyton roseum and Sarcophyton acutum.
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Tan, Ee Suan, Hirono Hamazato, Takahiro Ishii, Kenshiro Taira, Yuki Takeuchi, Hiroki Takekata, Naoko Isomura et Akihiro Takemura. « Does estrogen regulate vitellogenin synthesis in corals ? » Comparative Biochemistry and Physiology Part A : Molecular & ; Integrative Physiology 255 (mai 2021) : 110910. http://dx.doi.org/10.1016/j.cbpa.2021.110910.
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Norin, Tommy, Suzanne C. Mills, Amélie Crespel, Daphne Cortese, Shaun S. Killen et Ricardo Beldade. « Anemone bleaching increases the metabolic demands of symbiont anemonefish ». Proceedings of the Royal Society B : Biological Sciences 285, no 1876 (11 avril 2018) : 20180282. http://dx.doi.org/10.1098/rspb.2018.0282.
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Increased ocean temperatures are causing mass bleaching of anemones and corals in the tropics worldwide. While such heat-induced loss of algal symbionts (zooxanthellae) directly affects anemones and corals physiologically, this damage may also cascade on to other animal symbionts. Metabolic rate is an integrative physiological trait shown to relate to various aspects of organismal performance, behaviour and locomotor capacity, and also shows plasticity during exposure to acute and chronic stressors. As climate warming is expected to affect the physiology, behaviour and life history of animals, including ectotherms such as fish, we measured if residing in bleached versus unbleached sea anemones ( Heteractis magnifica ) affected the standard (i.e. baseline) metabolic rate and behaviour (activity) of juvenile orange-fin anemonefish ( Amphiprion chrysopterus ) . Metabolic rate was estimated from rates of oxygen uptake , and the standard metabolic rate of anemonefish from bleached anemones was significantly higher by 8.2% compared with that of fish residing in unbleached anemones, possibly due to increased stress levels. Activity levels did not differ between fish from bleached and unbleached anemones. As reflects the minimum cost of living, the increased metabolic demands may contribute to the negative impacts of bleaching on important anemonefish life history and fitness traits observed previously (e.g. reduced spawning frequency and lower fecundity).
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Abdel-Fattah, W. I., A. M. Sallam, I. H. Ibrahim et H. Ibrahim. « AC Electric Conductivity and Biochemical Analyses of Physiologic Solutions to Follow Biomimetic Coatings on Corals Impregnated with Ag or Zn or Sr Ions ». Open Biomaterials Journal 1 (7 septembre 2009) : 1–9. http://dx.doi.org/10.2174/1876502500901010001.
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Nofiani, Risa, Alexandra J. Weisberg, Takeshi Tsunoda, Ruqiah Ganda Putri Panjaitan, Ridho Brilliantoro, Jeff H. Chang, Benjamin Philmus et Taifo Mahmud. « Antibacterial Potential of Secondary Metabolites from Indonesian Marine Bacterial Symbionts ». International Journal of Microbiology 2020 (29 juin 2020) : 1–11. http://dx.doi.org/10.1155/2020/8898631.
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Indonesian http://mts.hindawi.com/update/) in our Manuscript Tracking System and after you have logged in click on the ORCID link at the top of the page. This link will take you to the ORCID website where you will be able to create an account for yourself. Once you have done so, your new ORCID will be saved in our Manuscript Tracking System automatically."?>marine environments are known to house diverse organisms. However, the potential for bacteria from these environments as a source of antibacterial agents has not been widely studied. This study aims to explore the antibacterial potential of secondary metabolites produced by bacterial symbionts from sponges and corals collected in the Indonesian waters. Extracts of 12 bacterial isolates from sponges or corals were prepared by cultivating the bacteria under a number of different media conditions and using agar well diffusion assays to test for antibacterial activity. In addition, the morphology, physiology, and biochemical characteristics and 16S rRNA sequence of each isolate were used to determine their taxonomic classification. All tested bacterial isolates were able to produce secondary metabolites with various levels of antibacterial activity depending on medium composition and culture conditions. Two of the bacteria (RS3 and RC4) showed strong antibacterial activities against both Gram-negative and Gram-positive bacteria. A number of isolates (RS1, RS3, and RC2) were co-cultured with mycolic acid-containing bacteria, Mycobacterium smegmatis or Rhodococcus sp. However, no improvements in their antibacterial activity were observed. All of the 12 bacteria tested were identified as Streptomyces spp. LC-MS analysis of EtOAc extracts from the most active strains RS3 and RC4 revealed the presence of a number of dactinomycin analogues and potentially new secondary metabolites. Symbiotic Streptomyces spp. from sponges and corals of the Indonesian marine environments have great potential as a source of broad-spectrum antibacterial agents.
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Tarrant, Ann M., C. H. Blomquist, P. H. Lima, M. J. Atkinson et S. Atkinson. « Metabolism of estrogens and androgens by scleractinian corals ». Comparative Biochemistry and Physiology Part B : Biochemistry and Molecular Biology 136, no 3 (novembre 2003) : 473–85. http://dx.doi.org/10.1016/s1096-4959(03)00253-7.
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Wangpraseurt, Daniel, Mads Lichtenberg, Steven L. Jacques, Anthony W. D. Larkum et Michael Kühl. « Optical Properties of Corals Distort Variable Chlorophyll Fluorescence Measurements ». Plant Physiology 179, no 4 (28 janvier 2019) : 1608–19. http://dx.doi.org/10.1104/pp.18.01275.
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Keshavmurthy, Shashank, Kuo-Hsun Tang, Chia-Min Hsu, Chai-Hsia Gan, Chao-Yang Kuo, Keryea Soong, Hong-Nong Chou et Chaolun Allen Chen. « Symbiodiniumspp. associated with scleractinian corals from Dongsha Atoll (Pratas), Taiwan, in the South China Sea ». PeerJ 5 (18 janvier 2017) : e2871. http://dx.doi.org/10.7717/peerj.2871.
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Dongsha Atoll (also known as Pratas) in Taiwan is the northernmost atoll in the South China Sea and a designated marine national park since 2007. The marine park’s scope of protection covers the bio-resources of its waters in addition to uplands, so it is important to have data logging information and analyses of marine flora and fauna, including their physiology, ecology, and genetics. As part of this effort, we investigatedSymbiodiniumassociations in scleractinian corals from Dongsha Atoll through surveys carried out at two depth ranges (shallow, 1–5 m; and deep, 10–15 m) in 2009 and during a bleaching event in 2010.Symbiodiniumcomposition was assessed using restriction fragment length polymorphism (RFLP) of 28S nuclear large subunit ribosomal DNA (nlsrDNA). Our results showed that the 796 coral samples from seven families and 20 genera collected in 2009 and 132 coral samples from seven families and 12 genera collected in 2010 were associated withSymbiodiniumC, D and C+D. Occurrence of clade D in shallow water (24.5%) was higher compared to deep (14.9%). Due to a bleaching event in 2010, up to 80% of coral species associated withSymbiodiniumC underwent moderate to severe bleaching. Using the fine resolution technique of denaturing gradient gel electrophoresis (DGGE) of internal transcribed spacer 2 (ITS2) in 175 randomly selected coral samples, from 2009 and 2010, eightSymbiodiniumC types and twoSymbiodiniumD types were detected. This study is the first baseline survey onSymbiodiniumassociations in the corals of Dongsha Atoll in the South China Sea, and it shows the dominance ofSymbiodiniumclade C in the population.
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Clapham, Matthew E., et Paul R. Renne. « Flood Basalts and Mass Extinctions ». Annual Review of Earth and Planetary Sciences 47, no 1 (30 mai 2019) : 275–303. http://dx.doi.org/10.1146/annurev-earth-053018-060136.
Texte intégralRésumé :
Flood basalts were Earth's largest volcanic episodes that, along with related intrusions, were often emplaced rapidly and coincided with environmental disruption: oceanic anoxic events, hyperthermals, and mass extinction events. Volatile emissions, both from magmatic degassing and vaporized from surrounding rock, triggered short-term cooling and longer-term warming, ocean acidification, and deoxygenation. The magnitude of biological extinction varied considerably, from small events affecting only select groups to the largest extinction of the Phanerozoic, with less-active organisms and those with less-developed respiratory physiology faring especially poorly. The disparate environmental and biological outcomes of different flood basalt events may at first order be explained by variations in the rate of volatile release modulated by longer trends in ocean carbon cycle buffering and the composition of marine ecosystems. Assessing volatile release, environmental change, and biological extinction at finer temporal resolution should be a top priority to refine ancient hyperthermals as analogs for anthropogenic climate change. ▪ Flood basalts, the largest volcanic events in Earth history, triggered dramatic environmental changes on land and in the oceans. ▪ Rapid volcanic carbon emissions led to ocean warming, acidification, and deoxygenation that often caused widespread animal extinctions. ▪ Animal physiology played a key role in survival during flood basalt extinctions, with reef builders such as corals being especially vulnerable. ▪ The rate and duration of volcanic carbon emission controlled the type of environmental disruption and the severity of biological extinction.
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Blomquist, Charles H., P. H. Lima, A. M. Tarrant, M. J. Atkinson et S. Atkinson. « 17β-Hydroxysteroid dehydrogenase (17β-HSD) in scleractinian corals and zooxanthellae ». Comparative Biochemistry and Physiology Part B : Biochemistry and Molecular Biology 143, no 4 (avril 2006) : 397–403. http://dx.doi.org/10.1016/j.cbpb.2005.12.017.
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Rodolfo-Metalpa, Riccardo, et Christine Ferrier-Pagés. « Physiological responses of Mediterranean corals to temperature and pH perturbations ». Comparative Biochemistry and Physiology Part A : Molecular & ; Integrative Physiology 153, no 2 (juin 2009) : S168. http://dx.doi.org/10.1016/j.cbpa.2009.04.348.
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Goodbody-Gringley, Gretchen, Stephane Martinez, Jessica Bellworthy, Alex Chequer, Hagai Nativ et Tali Mass. « Irradiance driven trophic plasticity in the coral Madracis pharensis from the Eastern Mediterranean ». Scientific Reports 14, no 1 (13 février 2024). http://dx.doi.org/10.1038/s41598-024-54217-3.
Texte intégralRésumé :
AbstractThe distribution of symbiotic scleractinian corals is driven, in part, by light availability, as host energy demands are partially met through translocation of photosynthate. Physiological plasticity in response to environmental conditions, such as light, enables the expansion of resilient phenotypes in the face of changing environmental conditions. Here we compared the physiology, morphology, and taxonomy of the host and endosymbionts of individual Madracis pharensis corals exposed to dramatically different light conditions based on colony orientation on the surface of a shipwreck at 30 m depth in the Bay of Haifa, Israel. We found significant differences in symbiont species consortia, photophysiology, and stable isotopes, suggesting that these corals can adjust multiple aspects of host and symbiont physiology in response to light availability. These results highlight the potential of corals to switch to a predominantly heterotrophic diet when light availability and/or symbiont densities are too low to sustain sufficient photosynthesis, which may provide resilience for corals in the face of climate change.
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Ross, Claire L., Andrew Warnes, Steeve Comeau, Christopher E. Cornwall, Michael V. W. Cuttler, Melissa Naugle, Malcolm T. McCulloch et Verena Schoepf. « Coral calcification mechanisms in a warming ocean and the interactive effects of temperature and light ». Communications Earth & ; Environment 3, no 1 (30 mars 2022). http://dx.doi.org/10.1038/s43247-022-00396-8.
Texte intégralRésumé :
AbstractOcean warming is transforming the world’s coral reefs, which are governed by the growth of marine calcifiers, most notably branching corals. Critical to skeletal growth is the corals’ regulation of their internal chemistry to promote calcification. Here we investigate the effects of temperature and light on the calcifying fluid chemistry (using boron isotope systematics), calcification rates, metabolic rates and photo-physiology of Acropora nasuta during two mesocosm experiments simulating seasonal and static temperature and light regimes. Under the seasonal regime, coral calcification rates, calcifying fluid carbonate chemistry, photo-physiology and metabolic productivity responded to both changes in temperature and light. However, under static conditions the artificially prolonged exposure to summer temperatures resulted in heat stress and a heightened sensitivity to light. Our results indicate that temperature and light effects on coral physiology and calcification mechanisms are interactive and context-specific, making it essential to conduct realistic multi-variate dynamic experiments in order to predict how coral calcification will respond to ocean warming.
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JOGEE, SHAKEEL YAVAN, SRUTI JEETUN, MELANIE RICOT, NAWSHEEN TALEB-HOSSENKHAN, SUSHMA MATTAN-MOORGAWA, DEEPEEKA KAULLYSING, PAULINE RIEMANN et al. « Photo-physiology of healthy-looking and diseased/health-compromised hard corals from Mauritius Island, Western Indian Ocean ». Indo Pacific Journal of Ocean Life 7, no 1 (31 janvier 2023). http://dx.doi.org/10.13057/oceanlife/o070103.
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Abstract. Jogee SY, Jeetun S, Ricot M, Taleb-Hossenkhan N, Mattan-Moorgawa S, Kaullysing D, Riemann P, Blanc L, Casareto BE, Suzuki Y, Bhagooli R. 2023. Photo-physiology of healthy-looking and diseased/health-compromised hard corals from Mauritius Island, Western Indian Ocean. Indo Pac J Ocean Life 7: 27-37. The spatial photo-physiological responses of in hospite zooxanthellae in hard corals, including coenosarc and polyps, healthy-looking and affected parts in four coral diseases, namely Brown Band, Black Band, Skeletal Eroding Band and White Band on the coral Acropora muricata, and two health-compromised conditions such as the Pink Pigmentation Response and its differentiated morphology, the Pink Line Syndrome, on the coral Porites were investigated using the Imaging-PAM fluorometry. A significantly lower Fv/Fm was observed in case of Black Band, White Band, Brown Band and Pink Pigmentation Response affected parts compared to the healthy-looking parts. The Fv/Fm had the highest decline in Brown Band disease. Both the polyps and coenosarc had significantly lower Fv/Fm in White Band and Brown Band diseased parts compared to their healthy-looking parts. The rETRmax did not change significantly between diseased/health-comprised parts and healthy-looking parts. NPQmax declined significantly in White Band, Black Band and Pink Pigmentation Response cases. ? and ? generally did not tend to be affected in diseased/health-compromised conditions. The photo-physiology of in hospite zooxanthellae was least affected in Pink Line Syndrome. These findings suggest that diseased/health-compromised parts of corals behave differently in terms of their photo-physiology in different diseased and health-compromised coral conditions in important reef-building corals species such as A. muricata and Porites species, with important implications for the productivity and thus adaptive management of coral reefs in a globally warming ocean.
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Taenzer, Lina, Scott D. Wankel, Jason Kapit, William A. Pardis, Santiago Herrera, Steven Auscavitch, Kalina C. Grabb, Erik Cordes et Colleen M. Hansel. « Corals and sponges are hotspots of reactive oxygen species in the deep sea ». PNAS Nexus, 15 novembre 2023. http://dx.doi.org/10.1093/pnasnexus/pgad398.
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Abstract Reactive oxygen species (ROS) are central to diverse biological processes through which organisms respond to and interact with their surroundings. Yet, a lack of direct measurements limits our understanding of the distribution of ROS in the ocean. Using a recently developed in situ sensor, we show that deep-sea corals and sponges produce the ROS superoxide, revealing that benthic organisms can be sources and hotspots of ROS production in these environments. These findings confirm previous contentions that extracellular superoxide production by corals can be independent of the activity of photosynthetic symbionts. The discovery of deep-sea corals and sponges as sources of ROS has implications for the physiology and ecology of benthic organisms and introduces a previously overlooked suite of redox reactants at depth.
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Overmans, Sebastian, et Susana Agustí. « Differential susceptibility of Red Sea Pocilloporidae corals to UVB highlights photoacclimation potential ». Frontiers in Marine Science 10 (13 mars 2023). http://dx.doi.org/10.3389/fmars.2023.847559.
Texte intégralRésumé :
Despite being exposed to extreme water temperatures and solar irradiances, Red Sea corals are relatively resistant to bleaching. While their thermal tolerance is well described, little is known about their resistance to ultraviolet-B radiation (UVB). Here, we performed a short-term (2 days) UVB-removal incubation with Stylophora pistillata, and in situ measurements with Pocillopora verrucosa complemented by a long-term (46 days) transplantation and UVB-removal experiment. Using a suite of physiological parameters (effective quantum yield (Fv’/Fm’), oxidative stress (lipid peroxidation, LPO), and primary production), we assessed the impacts of UVB on the physiology and acclimation capacity of Red Sea corals. Shielding S. pistillata from UVB did not change the gross primary production or Fv’/Fm’, and respiration and LPO in the host remained unaffected. In situ, P. verrucosa exhibited less varying and significantly higher Fv’/Fm’ in 8 m depth (0.61 ± 0.04) than in 4 m (0.52 ± 0.06), 2 m (0.51 ± 0.09), and 0.5 m (0.50 ± 0.11), where water temperatures ranged from 30.5–33.4, 30.6–34.0, 30.8–34.5, 30.6–37.3°C and daily UVB exposures averaged 0.9, 2.9, 11.8 and 21.4 kJ m-2, respectively. Fv’/Fm’ correlated the strongest with UVB (-0.57), followed by PAR (-0.54) and temperature (-0.40), suggesting that UVB is a key determinant of photosynthetic efficiency. Fv’/Fm’ of upward transplanted specimens (T 1m) was initially decreased but gradually increased and reached the same values as shallow corals (1 m) after 44 days. UVB removal significantly increased the Fv’/Fm’ of transplanted corals in the first 20 days. Oxidative stress was initially highest in T 1m samples under full sunlight but equalized with 1 m specimens by day 46, whereas oxidative stress was significantly reduced by day 4 in T 1m corals sheltered from UVB. Overall, UVB-removal generally had little impact on the physiology of shallow-water S. pistillata and P. verrucosa but considerably accelerated the acclimation of upward transplanted corals. Our study highlights that UVB is a crucial stressor governing the photoacclimation capacity of these Red Sea coral species.
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Bouwmeester, Jessica, Jonathan Daly, Nikolas Zuchowicz, Claire Lager, E. Michael Henley, Mariko Quinn et Mary Hagedorn. « Solar radiation, temperature and the reproductive biology of the coral Lobactis scutaria in a changing climate ». Scientific Reports 13, no 1 (5 janvier 2023). http://dx.doi.org/10.1038/s41598-022-27207-6.
Texte intégralRésumé :
AbstractCoral reefs worldwide are at risk due to climate change. Coral bleaching is becoming increasingly common and corals that survive bleaching events can suffer from temporary reproductive failure for several years. While water temperature is a key driver in causing coral bleaching, other environmental factors are involved, such as solar radiation. We investigated the individual and combined effects of temperature, photosynthetically active radiation (PAR), and ultraviolet radiation (UVR) on the spawning patterns and reproductive physiology of the Hawaiian mushroom coral Lobactis scutaria, using long-term experiments in aquaria. We examined effects on spawning timing, fertilisation success, and gamete physiology. Both warmer temperatures and filtering UVR altered the timing of spawning. Warmer temperatures caused a drop in fertilisation success. Warmer temperatures and higher PAR both negatively affected sperm and egg physiology. These results are concerning for the mushroom coral L. scutaria and similar reproductive data are urgently needed to predict future reproductive trends in other species. Nonetheless, thermal stress from global climate change will need to be adequately addressed to ensure the survival of reef-building corals in their natural environment throughout the next century and beyond. Until then, reproduction is likely to be increasingly impaired in a growing number of coral species.