11 results on '"Grover, Renaud"'
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2. Desert dust deposition supplies essential bioelements to Red Sea corals.
- Author
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Blanckaert, Alice C. A., Omanović, Dario, Fine, Maoz, Grover, Renaud, and Ferrier‐Pagès, Christine
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CORAL bleaching ,CORALS ,OCEAN temperature ,PHOTOSYNTHETIC rates ,DUST storms ,IRON ,DUST - Abstract
Climate change‐related increase in seawater temperature has become a leading cause of coral bleaching and mortality. However, corals from the northern Red Sea show high thermal tolerance and no recorded massive bleaching event. This specific region is frequently subjected to intense dust storms, coming from the surrounding arid deserts, which are expected to increase in frequency and intensity in the future. The aerial dust deposition supplies essential bioelements to the water column. Here, we investigated the effect of dust deposition on the physiology of a Red Sea coral, Stylophora pistillata. We measured the modifications in coral and Symbiodiniaceae metallome (cellular metal content), as well as the changes in photosynthesis and oxidative stress status of colonies exposed during few weeks to dust deposition. Our results show that 1 mg L−1 of dust supplied nanomolar amounts of nitrate and other essential bioelements, such as iron, manganese, zinc and copper, rapidly assimilated by the symbionts. At 25°C, metal bioaccumulation enhanced the chlorophyll concentration and photosynthesis of dust‐exposed corals compared to control corals. These results suggest that primary production was limited by metal availability in seawater. A 5°C increase in seawater temperature enhanced iron assimilation in both control and dust‐enriched corals. Temperature rise increased the photosynthesis of control corals only, dust‐exposed ones having already reached maximal photosynthesis rates at 25°C. Finally, we observed a combined effect of temperature and bioelement concentration on the assimilation of molybdenum, cadmium, manganese and copper, which were in higher concentrations in symbionts of dust‐exposed corals maintained at 30°C. All together these observations highlight the importance of dust deposition in the supply of essential bioelements, such as iron, to corals and its role in sustaining coral productivity in Red Sea reefs. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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3. Nutrient starvation impairs the trophic plasticity of reef‐building corals under ocean warming.
- Author
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Ezzat, Leïla, Maguer, Jean‐François, Grover, Renaud, Rottier, Cécile, Tremblay, Pascale, Ferrier‐Pagès, Christine, and Field, Katie
- Subjects
CORAL bleaching ,CORALS ,OCEAN acidification ,STARVATION ,THERMAL stresses ,NUTRIENT uptake ,MATERIAL plasticity - Abstract
Copyright of Functional Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2019
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4. Autotrophic carbon budget in coral tissue: a new 13C-based model of photosynthate translocation.
- Author
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Tremblay, Pascale, Grover, Renaud, Maguer, Jean François, Legendre, Louis, and Ferrier-Pagès, Christine
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BIOLOGY experiments , *CORALS , *DINOFLAGELLATES , *PHOTOSYNTHATES , *CARBON , *GASES from plants , *SALINE waters - Abstract
Corals live in symbiosis with dinoflagellates of the genus Symbiodinum. These dinoflagellates translocate a large part of the photosynthetically fixed carbon to the host, which in turn uses it for its own needs. Assessing the carbon budget in coral tissue is a central question in reef studies that still vexes ecophysiologists. The amount of carbon fixed by the symbiotic association can be determined by measuring the rate of photosynthesis, but the amount of carbon translocated by the symbionts to the host and the fate of this carbon are more difficult to assess. In the present study, we propose a novel approach to calculate the budget of autotrophic carbon in the tissue of scleractinian corals, based on a new model and measurements made with the stable isotope 13C. Colonies of the scleractinian coral Stylophora pistillata were incubated in H13CO -3-enriched seawater, after which the fate of 13C was followed in the symbionts, the coral tissue and the released particulate organic carbon (i.e. mucus). Results obtained showed that after 15 min, ca. 60% of the carbon fixed was already translocated to the host, and after 48 h, this value reached 78%. However, ca. 48% of the photosynthetically fixed carbon was respired by the symbiotic association, and 28% was released as dissolved organic carbon. This is different from other coral species, where <1% of the total organic carbon released is from newly fixed carbon. Only 23% of the initially fixed carbon was retained in the symbionts and coral tissue after 48 h. Results show that our 13C-based model could successfully trace the carbon flow from the symbionts to the host, and the photosynthetically acquired carbon lost from the symbiotic association. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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5. High phosphate uptake requirements of the scleractinian coral Stylophora pistillata.
- Author
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Godinot, Claire, Grover, Renaud, Allemand, Denis, and Ferrier-Pagès, Christine
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NUTRIENT uptake , *PHOSPHATES , *INORGANIC compounds , *SCLERACTINIA , *CORALS - Abstract
Several untested aspects of the regulation of inorganic nutrient uptake were examined using nutrient depletion experiments with the symbiotic coral Stylophora pistillata. The total inhibition of phosphate uptake in artificial seawater lacking sodium indicates the involvement of a sodium/phosphate symporter for the uptake of phosphate across host membranes. Addition of ammonium or nitrate (up to 6.0 μmol l-1) did not enhance saturated phosphate uptake rates, thus indicating that corals, or their symbiotic algae, were not, or not sufficiently, nitrogen limited to modify their phosphate needs. Conversely, the saturated uptake rate of ammonium increased by 2.5-fold in the presence of 3.0 μmol l-1 of phosphate, thus indicating that the corals or their symbionts were lacking intracellular phosphate to take advantage of the inorganic nitrogen compounds dissolved in their surrounding medium. Overall, these results highlight some greater limitation in phosphate rather than in nitrogen. Finally, the rate of phosphate uptake decreased with particulate feeding of the host (organic phosphate source). Indeed, corals that were fed 1 and 3 days before the uptake experiment took up phosphate 42 and 19% slower, respectively, than corals that were fed 21 days before. This result provides additional evidence of phosphate limitation in S. pistillata. This study therefore brings new insights into the relationships between nutrients and symbiotic corals, and may provide a rapid and effective tool to investigate which nutrient is the most limiting for coral metabolism. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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6. Uptake of dissolved free amino acids by the scleractinian coral Stylophora pistillata.
- Author
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Grover, Renaud, Maguer, Jean-François, Allemand, Denis, and Ferrier-Pagès, Christine
- Subjects
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STYLOPHORA , *NITROGEN excretion , *METABOLISM , *URINALYSIS , *NITROGEN compounds , *DEVELOPMENTAL biology - Abstract
This study was designed to assess the importance of dissolved free amino acids (DFAA) as a nitrogen source for the scieractinian coral Stylophora pistillata. For this purpose, experiments were performed using 15N-enriched DFAAs, and %15N enrichment was measured both in animal tissue and zooxanthellae at different DFAA concentrations, incubation time and light levels. As previously observed for urea, which is another source of organic nitrogen, DFAA uptake exhibited a biphasic mode consisting of an active carrier-mediated transport for concentrations below 3 μmol-1 and a linear uptake for higher concentrations. The value of the carrier affinity (Km=1.23 μmol l-1 DFAA) indicated good adaptation of the corals to the low levels of DFAA concentrations measured in most oligotrophic waters. DFAA uptake was also correlated with light. The DFAA contribution to the nitrogen requirements for tissue growth was compared to the contribution of ammonia, nitrate and urea, for which uptake was also measured in S. pistillata. Inorganic sources (NH4+ and NO3-) contributed 75% of the daily nitrogen needs against 24% for organic sources. Taken altogether, dissolved organic and inorganic nitrogen can supply almost 100% of the nitrogen needs for tissue growth. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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7. Urea uptake by the scleractinian coral Stylophora pistillata
- Author
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Grover, Renaud, Maguer, Jean-François, Allemand, Denis, and Ferrier-Pagès, Christine
- Subjects
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NITROGEN excretion , *METABOLISM , *URINE , *NITROGEN - Abstract
Abstract: Urea can be one of the major sources of nitrogen for phytoplankton, but little is known about its importance for corals. Experiments were therefore designed to assess the uptake rates of urea by the scleractinian coral Stylophora pistillata; 15N-urea was used to follow the incorporation of nitrogen into the zooxanthellae and animal tissue. The uptake kinetics of urea in the tissue of S. pistillata showed that there is a concentration-dependent uptake of urea. The transport of urea was composed of a linear component (diffusion) at concentrations higher than 6 μmol N-urea l−1 and an active carrier-mediated component, at lower concentrations. The value of the carrier affinity (K m =1.05 μmol urea l−1) indicates a good adaptation of the corals to low levels of urea in seawater. At the in situ concentration of ca. 0.2 μmol N-urea l−1, the uptake rate was equal to 0.1 nmol N h−1 cm−2. Urea uptake was at least four times higher in the animal than in the algal fraction, and five times higher when corals were incubated in the light than in the dark. These results could be explained by the involvement of urea in the calcification process, which is also enhanced by light. Comparison of urea uptake rates with nitrate or ammonium uptake rates for the same S. pistillata species, at in situ concentrations, showed that urea is preferred to nitrate and may therefore be an important source of nitrogen for scleractinian corals. [Copyright &y& Elsevier]
- Published
- 2006
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8. Low levels of ultra-violet radiation mitigate the deleterious effects of nitrate and thermal stress on coral photosynthesis.
- Author
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Blanckaert, Alice C.A., de Barros Marangoni, Laura Fernandes, Rottier, Cécile, Grover, Renaud, and Ferrier-Pagès, Christine
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CORAL bleaching ,SCLERACTINIA ,CORALS ,PHOTOSYNTHESIS ,OCEAN temperature ,NITRATES ,THERMAL stresses - Abstract
Reef ecosystems are under increasing pressure from global and local stressors. Rising seawater temperature and high ultraviolet radiation (UVR) levels are the main drivers of the disruption of the coral-dinoflagellate symbiosis (bleaching). Bleaching can also be exacerbated by nitrate contamination in coastal reefs. However, the underlying physiological mechanisms are still poorly understood. Here, we assessed the physiological and oxidative state of the scleractinian coral Pocillopora damicornis , maintained eight weeks in a crossed-factorial design including two temperatures (26 °C or 30 °C), and two nitrate (0.5 and 3 μM-enriched), and UVR (no UVR and 25/1.5 Wm
−2 UVA/B) levels. Nitrate enrichment, and high temperature, significantly impaired coral photosynthesis. However, UVR alleviated the nitrate and temperature-induced decrease in photosynthesis, by increasing the coral's antioxidant capacity. The present study contributes to our understanding of the combined effects of abiotic stressors on coral bleaching susceptibility. Such information is urgently needed to refine reef management strategies. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
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9. Tracing the Trophic Plasticity of the Coral–Dinoflagellate Symbiosis Using Amino Acid Compound-Specific Stable Isotope Analysis.
- Author
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Ferrier-Pagès, Christine, Martinez, Stephane, Grover, Renaud, Cybulski, Jonathan, Shemesh, Eli, and Tchernov, Dan
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STABLE isotope analysis ,AMINO acids ,SYMBIOSIS ,AMINO acid analysis ,NUTRITIONAL genomics - Abstract
The association between corals and photosynthetic dinoflagellates is one of the most well-known nutritional symbioses, but nowadays it is threatened by global changes. Nutritional exchanges are critical to understanding the performance of this symbiosis under stress conditions. Here, compound-specific δ
15 N and δ13 C values of amino acids (δ15 NAA and δ13 CAA ) were assessed in autotrophic, mixotrophic and heterotrophic holobionts as diagnostic tools to follow nutritional interactions between the partners. Contrary to what was expected, heterotrophy was mainly traced through the δ15 N of the symbiont's amino acids (AAs), suggesting that symbionts directly profit from host heterotrophy. The trophic index (TP) ranged from 1.1 to 2.3 from autotrophic to heterotrophic symbionts. In addition, changes in TP across conditions were more significant in the symbionts than in the host. The similar δ13 C-AAs signatures of host and symbionts further suggests that symbiont-derived photosynthates are the main source of carbon for AAs synthesis. Symbionts, therefore, appear to be a key component in the AAs biosynthetic pathways, and might, via this obligatory function, play an essential role in the capacity of corals to withstand environmental stress. These novel findings highlight important aspects of the nutritional exchanges in the coral–dinoflagellates symbiosis. In addition, they feature δ15 NAA as a useful tool for studies regarding the nutritional exchanges within the coral–symbiodiniaceae symbiosis. [ABSTRACT FROM AUTHOR]- Published
- 2021
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10. New insights into carbon acquisition and exchanges within the coral-dinoflagellate symbiosis under NH4+ and NO3- supply.
- Author
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Ezzat, Leïla, Maguer, Jean-François, Grover, Renaud, and Ferrier-Pagès, Christine
- Subjects
CORAL reef ecology ,DINOFLAGELLATES ,SYMBIOSIS ,AMMONIUM ,CARBON fixation ,NITRATES ,NUTRIENT cycles ,COASTAL ecology - Abstract
Anthropogenic nutrient enrichment affects the biogeochemical cycles and nutrient stoichiometry of coastal ecosystems and is often associated with coral reef decline. However, the mechanisms by which dissolved inorganic nutrients, and especially nitrogen forms (ammonium versus nitrate) can disturb the association between corals and their symbiotic algae are subject to controversial debate. Here, we investigated the coral response to varying N : P ratios, with nitrate or ammonium as a nitrogen source. We showed significant differences in the carbon acquisition by the symbionts and its allocation within the symbiosis according to nutrient abundance, type and stoichiometry. In particular, under low phosphate concentration (0.05 µM), a 3 µM nitrate enrichment induced a significant decrease in carbon fixation rate and low values of carbon translocation, compared with control conditions (N : P = 0.5 : 0.05), while these processes were significantly enhanced when nitrate was replaced by ammonium. A combined enrichment in ammonium and phosphorus (N : P = 3 : 1) induced a shift in nutrient allocation to the symbionts, at the detriment of the host. Altogether, these results shed light into the effect of nutrient enrichment on reef corals. More broadly, they improve our understanding of the consequences of nutrient loading on reef ecosystems, which is urgently required to refine risk management strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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11. Biochemical composition of the cold-water coral Dendrophyllia cornigera under contrasting productivity regimes: insights from lipid biomarkers and compound-specific isotopes
- Author
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Christine Ferrier-Pagès, Covadonga Orejas, Jordi Grinyó, Sascha Flögel, Renaud Grover, Andrea Gori, Lucía Rueda, Imma Tolosa, Nuria Viladrich, Principality of Monaco, European Commission, Gori, Andrea, Tolosa, Imma, Orejas, Covadonga, Rueda, Lucia, Viladrich, Núria, Grinyó, Jordi, Flögel, Sascha, Grover, Renaud, and Ferrier-Pagès, Christine
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0106 biological sciences ,010504 meteorology & atmospheric sciences ,Medio Marino y Protección Ambiental ,Coral ,Aquatic Science ,Biology ,Cold-water coral ,Oceanography ,01 natural sciences ,Mediterranean sea ,Phytoplankton ,Mediterranean Sea ,Dominance (ecology) ,14. Life underwater ,Fatty acids ,Centro Oceanográfico de Gijón ,Sterol ,0105 earth and related environmental sciences ,Trophic level ,Invertebrate ,Fatty alcohols ,δ13C ,Ecology ,010604 marine biology & hydrobiology ,fungi ,Lipid ,Fatty acid ,Lipids ,Sterols ,Productivity (ecology) ,Compound-specific stable isotope ,Fatty alcohol ,Cantabrian Sea ,lipids (amino acids, peptides, and proteins) ,Cold-water corals ,Compound-specific stable isotopes - Abstract
12 pages, 7 figures, 4 tables, supplementary material https://doi.org/10.1016/j.dsr.2018.08.010, The cold-water coral (CWC) Dendrophyllia cornigera is widely distributed in areas of both high and low productivity, suggesting a significant trophic plasticity of this coral depending on the food available in the environment. In this study, lipid biomarkers and their isotopic signature were compared in colonies of D. cornigera and sediment from the highly productive Cantabrian Sea (Northeast Atlantic Ocean) and the less productive Menorca Channel (Western Mediterranean Sea). Lipid content and composition in coral tissue clearly reflected the contrasting productivity in the two areas. Cantabrian corals presented higher content in fatty acids (FA), fatty alcohols and sterols than Menorca corals. Energy storage (saturated + mono-unsaturated FA) to structural (poly-unsaturated FA) ratio was higher in Cantabrian than in Menorca corals. The high ΣC20:1 content as well as PUFA(n-3)/PUFA(n-6) ratio suggest that Cantabrian corals mainly feed on phytoplankton and herbivorous grazers. This is also supported by the higher mono-unsaturated fatty alcohols (MUOH) and long chain mono-unsaturated fatty alcohols (LCMUOH) content in Cantabrian compared to Menorca corals. Conversely, higher PUFA(n-6) content in Menorca corals, with the dominance of C22:4(n-6) and C20:4(n-6), as well as the dominance of cholesterol and norC27Δ5,22 among sterols, point to a higher trophic role of dinoflagellates and invertebrates. The observed geographical variability in trophic ecology supports a high trophic plasticity of D. cornigera, which may favour the wide distribution of this CWC in areas with highly contrasted food availability, This work was supported by the Government of the Principality of Monaco, and by the European Project LIFE+ Indemares ‘Inventario y designación de la red natura 2000 en áreas marinas del estado español’ (LIFE07/NAT/E/000732)
- Published
- 2018
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