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Zvy Dubinsky - One of the best experts on this subject based on the ideXlab platform.
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uv b as a photoacclimatory enhancer of the Hermatypic Coral stylophora pistillata
Open Journal of Marine Science, 2013Co-Authors: Itay Cohen, Gal Dishon, David Iluz, Zvy DubinskyAbstract:Photoacclimation processes are crucial for the survival of all photosynthetic organisms in the photic zone. Changes in photosynthetic active radiation (PAR) are however simultaneous to changes in UV-B radiation. The influence of UV-B levels on bio-optical and physiological parameters of deep (30 m) Corals from the species Stylophora pistillata and their symbiotic algae, zooxanthellae, was examined during their gradual, stepwise acclimation to a shallow depth (3 m). Drastic exposure of deeper Corals to higher UV-B levels in shallower depths is usually fatal. Hence, the acclimation process lasted 118 days and included 10 intermediate stations with an addition of similar amount of PAR at each depth transfer. Concomitantly, in an on-shore experiment, fragments from the same colonies were acclimated by changing shading nets corresponding in PAR levels to each in situ station. Since UV-B is attenuated more efficiently than PAR in seawater, the PAR: UV-B ratio changes in the depth experiment while remaining constant under the neutral density nets. This provided the opportunity to evaluate the importance of UV-B to photoacclimation. In both experiments all fragments survived, in spite of a four-fold difference in levels of PAR and a 140-fold difference in UV-B flux between the initial and final conditions. Both experimental designs resulted in reduction of zooxanthellae density, photosynthesis rates, and quantum yields of PSII, while cellular chlorophyll content remained unaffected. Zooxanthellae density and maximal photosynthetic rate was found decreased in correlation with UV-B radiation, whether it was elevated logarithmically with reducing depths or linearly with reducing shades. Conversely, quantum yields of PSII were adjusted according to the enhancement of PAR rather than UV-B. We conclude that UV-B enhances the magnitude of photoacclimation to higher PAR. This novel aspect of photoacclimation can provide the basis for our understanding of the underlying mechanisms that result in UV-related bleaching.
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Effects of dissolved ammonium addition and host feeding with Artemia salina on photoacclimation of the Hermatypic Coral Stylophora pistillata
Marine Biology, 2000Co-Authors: Eduard A. Titlyanov, I. R. Fomina, Titlyanova Tv, V. Leletkin, N. Eden, A. Malkin, Zvy DubinskyAbstract:Effects of nutrient treatments on photoacclimation of the Hermatypic Coral Stylophora pistillata (Esper) were studied. Studies on photoacclimation of colonies from different light regimes in the field were evaluated and used to design laboratory experiments. Coral colonies were collected in the Gulf of Eilat (Israel) from January to March 1993. Exterior branches of colonies from different depths (1 to 40 m) displayed different trends in production characteristics at reduced and very low levels of illumination. From 24 ± 3% to 12 ± 2% of incident surface photosynthetic active radiation (PARo), zooxanthella population density and chlorophyll a+c per 106 zooxanthellae increased, a trend seen in the range of light levels optimal for Coral growth (90 to 30% PARo). The P max of CO2 per 106 zooxanthellae decreased, while P max of CO2 per 103 polyps increased, indicating an increase in zooxanthella population density at low light levels. Proliferous zooxanthella frequency (PZF, a measure of zooxanthella division) declined significantly at light levels
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effects of dissolved ammonium addition and host feeding with artemia salina on photoacclimation of the Hermatypic Coral stylophora pistillata
Marine Biology, 2000Co-Authors: Eduard A. Titlyanov, I. R. Fomina, V. Leletkin, N. Eden, A. Malkin, T V Titlyanova, Zvy DubinskyAbstract:Effects of nutrient treatments on photoacclimation of the Hermatypic Coral Stylophora pistillata (Esper) were studied. Studies on photoacclimation of colonies from different light regimes in the field were evaluated and used to design laboratory experiments. Coral colonies were collected in the Gulf of Eilat (Israel) from January to March 1993. Exterior branches of colonies from different depths (1 to 40 m) displayed different trends in production characteristics at reduced and very low levels of illumination. From 24 ± 3% to 12 ± 2% of incident surface photosynthetic active radiation (PARo), zooxanthella population density and chlorophyll a+c per 106 zooxanthellae increased, a trend seen in the range of light levels optimal for Coral growth (90 to 30% PARo). The P max of CO2 per 106 zooxanthellae decreased, while P max of CO2 per 103 polyps increased, indicating an increase in zooxanthella population density at low light levels. Proliferous zooxanthella frequency (PZF, a measure of zooxanthella division) declined significantly at light levels <18 ± 3% PARo. At the lowest levels of illumination (<5% PARo), zooxanthella population density decreased, as did the PZF; chl a+c per 106 zooxanthellae was unchanged. In 28-d experiments, exterior Coral branches from the upper surfaces of colonies from 3 m depth (65 ± 4% PARo) were incubated in aquaria under bright (80 to 90% PARo), reduced (20 to 30% PARo), and extremely low (2 to 4% PARo) light intensities. At each light intensity, the Corals were maintained in three feeding treatments: sea water (SW); ammonium enriched SW (SW + N); SW with Artemia salina nauplii (SW + A). An increase in P max of CO2 per 103 polyps was found in Corals acclimated to reduced light (20 to 30% PARo) in nutrient-enriched SW, while in SW, where the increase in zooxanthella population density was smaller, it did not occur. Nutrient enrichments (SW + N at 2 to 4% PARo and SW + A at 20 to 30% PARo) increased zooxanthella population density, but had no effect on chl a+c per 106 zooxanthellae. Acclimation for 14 d to reduced (10 to 20% PARo) and extremely low (1 to 3% PARo) light intensities shifted 14C photoassimilation into glycerol and other compounds (probably glycerides), rather than sugars. Both ammonium addition and feeding with Artemia salina nauplii resulted in an increase in photosynthetic assimilation of 14C into amino acids. We conclude that acclimation to reduced light consists of two processes: an increase in photosynthetic pigments and in zooxanthella population density. Both processes require nitrogen, the increase in zooxanthella population density needing more; this adaptation is therefore limited in nitrogen-poor sea water.
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autotrophy and predation in the Hermatypic Coral stylophora pistillata in different light habitats
Symbiosis, 2000Co-Authors: E A Titlyanov, V A Leletkin, Zvy DubinskyAbstract:The influence of light conditions in natural habitats on autotrophic function and also effects of light intensities, ammonium additions and feeding with zooplankton on predation of the Coral Stylophora pistillata in aquaria experiments were studied. Coral colonies were collected in the Gulf of Eilat (Israel) from depths 2 m, 20 m and 40 m. Some branches were maintained in aquaria during two weeks under different light regimes from 5% to 90% of PAR 0 and with different feeding treatments: seawater; seawater enriched with (NH 4 ) 2 SO 4 ; and seawater with the Artemia salina nauplii additions. It was shown that in exterior branches of the colonies zooxanthella population density and chlorophyll concentration (calculated as per polyp as per 10 6 zooxanthellae) increased with gradual reducing light intensity from 90% to 5% PARE, while the level of dividing zooxanthella frequency declined. With reducing light intensity from 20% to 5% PAR 0 an average volume of zooxanthellae and the ratio of values of maximal gross photosynthesis and dark respiration of Corals decreased. It was elucidated that ingestion rates as well as killing rates increased with reducing light intensity in the field and in the experimental aquaria. In most cases the value of the ratio of ingestion rate to killing rate was increased. Feeding of Corals with inorganic nitrogen as well as with zooplankton stimulated the ingestion rate. When Corals incubated under 90% and 20% PAR 0 in all feeding treatments the highest daily rate of predation observed at morning hours and lesser - at evening hours. Under light intensity 5% PAR 0 the rate of predation was high during the day in all feeding variants of the experiments. We conclude that with reducing light intensity in habitat the production capacities of autotrophic function of Corals increased by accumulation of algal-symbionts in exterior branches of Corals and by increasing photosynthetic pigment concentration in the algae. In all probabilities, it depended on intensification of predation under shade. We assume that Corals are capable of adapting to dim light not only by maximization of light absorption and its effective use, but also by intensification of heterotrophic function, at least predation.
Ichiro Takeuchi - One of the best experts on this subject based on the ideXlab platform.
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succession of delayed fluorescence correlated with Coral bleaching in the Hermatypic Coral acropora tenuis
Marine Pollution Bulletin, 2020Co-Authors: Ichiro Takeuchi, Daisuke Takaichi, Masakazu Katsumata, Hiroshi IshibashiAbstract:Abstract We investigated Coral bleaching by monitoring colour changes and measuring the delayed fluorescence (DF) of symbiotic dinoflagellates in the Hermatypic Coral Acropora tenuis, exposed to 1.0 μg/L Irgarol 1051 (photosystem II herbicide) for 14 d. The Irgarol concentration corresponded to those from international port regions of the world. The Coral colour and DFs under the control treatment were stable throughout the experiment, whereas under the Irgarol treatment the Corals showed gradual bleaching. The Irgarol treatment caused a rapid decrease in the slow decay DF component (10.1–60.0 s), while the fast decay DF component (0.1–10.0 s) decreased significantly after 6 d. The significant correlation between the latter values and the Coral colour indicates that if the electron accumulation function of quinones QA and QB is compromised, Corals will bleach. The present study will contribute to the understanding of the mechanism involved in bleaching of Coral exposed to herbicides.
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effects of ecologically relevant concentrations of irgarol 1051 in tropical to subtropical coastal seawater on Hermatypic Coral acropora tenuis and its symbiotic dinoflagellates
Marine Pollution Bulletin, 2020Co-Authors: Misato Kamei, Hiroshi Ishibashi, Kotaro Takayama, Ichiro TakeuchiAbstract:Abstract The effects of ecologically relevant concentrations of Irgarol 1051, a representative PSII herbicide, on Hermatypic Corals were studied in the laboratory. The colour and chlorophyll fluorescence of Acropora tenuis were examined following exposure to around ambient concentrations of Irgarol 1051 (20 ng/L and 200 ng/L) for 7 days. While the colour of Corals was stable throughout the experiment at both concentrations, the maximum effective quantum yield (ΔF/Fm′) of symbiotic dinoflagellates decreased with increasing Irgarol 1051 concentration (day 7: 8%, 20 ng/L; 37%, 200 ng/L). The expression of heat shock protein (HSP) 70 and 90 in symbiotic dinoflagellates was upregulated after 7 days exposure to both Irgarol concentrations, whereas HSP90 in Coral was not upregulated. The findings of the present study suggest that the threshold of chlorophyll fluorescence and HSP expression in symbiotic dinoflagellates is lower than 20 ng/L, which is around ecologically relevant concentrations in tropical to subtropical waters.
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usage of uv curable oligomer based adhesive agent in Hermatypic Coral experimental research
MethodsX, 2019Co-Authors: Ichiro Takeuchi, Hideyuki Yamashiro, Mikako GushiAbstract:Abstract The global decline of the tropical and subtropical Coral reefs requires urgent completion of various experiments that will reveal the factors influencing Coral health. We describe the procedure of a new inexpensive, easy, and fast method for attaching fragments of the Hermatypic Coral Acropora spp. to small polycarbonate hexagon head bolts using Bondic®, an ultraviolet (UV)-curable oligomer-based adhesive agent made by Laser Bonding Tech, Inc. (Aurora, ON, Canada). The attachment was hardened within 10 s after applying the adhesive to the cut surface of the Coral fragment. The Corals attached to polycarbonate bolt were tolerant to long-distance aerial transport 3 days after the attachment. In addition to its implementation in various experiments using Hermatypic Corals, this method will contribute to aquaculture of Hermatypic Corals, exhibition of Corals in aquariums, and Coral reef restoration. The advantages of this new method are summarized below: • A new UV-curable oligomer-based adhesive agent is used as an artificial substrate for Coral. • This method is inexpensive, easy to use, and Coral attaches quickly to the artificial substrate. • Corals attached to the artificial substrate can withstand long periods of transportation.
Michael Tedengren - One of the best experts on this subject based on the ideXlab platform.
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effects of the multiple stressors copper and reduced salinity on the metabolism of the Hermatypic Coral porites lutea
Marine Environmental Research, 2001Co-Authors: S Alutoin, J Boberg, Magnus Nystrom, Michael TedengrenAbstract:Abstract This study investigates the physiological responses in the Hermatypic Coral Porites lutea when exposed to a combination of reduced salinity (from ambient 30 psu to 20 psu) and two concentrations of copper (CuSO4), 10 μg l−1 and 30 μg l−1. Corals were exposed for 14 h and changes in metabolism in terms of primary production rate per chlorophyll a and respiration per surface area (cm2) were used as measures of stress. The results showed no significant changes in respiration rate in any of the treatments compared with controls, or between treatments. The primary production rate, however, displayed a more complex pattern. Corals exposed to reduced salinity, 30 μg l−1 copper, and the combination of the two stressors significantly reduced the production rate, whereas Corals exposed to 10 μg l−1 only, remained unaffected. However, adding 10 μg l−1 copper to reduced salinity did not affect the production rate thus indicating an antagonistic effect.
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simultaneous and sequential stress from increased temperature and copper on the metabolism of the Hermatypic Coral porites cylindrica
Marine Biology, 2001Co-Authors: Magnus Nystrom, I Nordemar, Michael TedengrenAbstract:Stressors arising from human activities may interact not only with each other, but also with natural disturbances. However, experimental studies on disturbance complexity and physiological responses of Corals to sublethal stresses, especially those due to human activities, are surprisingly few. In this study we investigated the stress response of the scleractinian Coral Porites cylindrica after 24 h of exposure to copper (11 µg Cu l–1) and increased temperature (following a 4°C above-ambient curve), separately and in combination. We also investigated the effect of sequential stress where Corals pre-exposed to increased temperature for 24 h were exposed to copper (for 24 h) after a 5-day recovery period. Changes in gross primary production (Pg: per milligram chlorophyll a per hour) and respiration (R:per square centimeter per hour) in terms of dissolved oxygen were used as indicators of stress. The results show that heat and the combination of heat and copper significantly reduced production rate. However, Corals exposed to elevated temperature displayed a significantly higher production rate following the 5-day recovery period. The combination of the two stressors showed no additive or synergistic effects. Copper alone had no effect on the production rate. However, Corals that were pre-exposed to increased temperature and again exposed to copper after 5 days displayed a significant reduction in production rate. The respiration rate was significantly reduced by all treatments, although no significant differences between treatments were detected. The results presented here illustrate how a stressor that does not affect Corals when acting in isolation may do so in sequential combination with other stressors.
Jose I Carreto - One of the best experts on this subject based on the ideXlab platform.
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palythine threonine a major novel mycosporine like amino acid maa isolated from the Hermatypic Coral pocillopora capitata
Journal of Photochemistry and Photobiology B-biology, 2009Co-Authors: Mario O Carignan, Karina H M Cardozo, Diogo Oliveirasilva, Pio Colepicolo, Jose I CarretoAbstract:Abstract Using a high-resolution reverse-phase liquid chromatography method we found that the tissues of the Hermatypic Coral Pocillopora capitata (collected in Santiago Bay, Mexico) contain a high diversity of primary and secondary mycosporine-like amino acids (MAAs) typical of some reef-building Coral species: mycosporine–glycine, shinorine, porphyra-334, mycosporine–methylamine–serine, mycosporine–methylamine–threonine, palythine–serine, palythine and one additional novel predominant MAA, with an absorbance maximum of 320 nm. Here we document the isolation and characterization of this novel MAA from the Coral P. capitata. Using low multi-stage mass analyses of deuterated and non deuterated compounds, high-resolution mass analyses (Time of Flight, TOF) and other techniques, this novel compound was characterized as palythine–threonine. Palythine–threonine was also present in high concentrations in the Corals Pocillopora eydouxi and Stylophora pistillata indicating a wider distribution of this MAA among reef-building Corals. From structural considerations we suggest that palythine–threonine is formed by decarboxylation of porphyra-334 followed by demethylation of mycosporine–methylamine–threonine.
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Palythine–threonine, a major novel mycosporine-like amino acid (MAA) isolated from the Hermatypic Coral Pocillopora capitata
Journal of Photochemistry and Photobiology B-biology, 2008Co-Authors: Mario O Carignan, Karina H M Cardozo, Pio Colepicolo, Diogo Oliveira-silva, Jose I CarretoAbstract:Abstract Using a high-resolution reverse-phase liquid chromatography method we found that the tissues of the Hermatypic Coral Pocillopora capitata (collected in Santiago Bay, Mexico) contain a high diversity of primary and secondary mycosporine-like amino acids (MAAs) typical of some reef-building Coral species: mycosporine–glycine, shinorine, porphyra-334, mycosporine–methylamine–serine, mycosporine–methylamine–threonine, palythine–serine, palythine and one additional novel predominant MAA, with an absorbance maximum of 320 nm. Here we document the isolation and characterization of this novel MAA from the Coral P. capitata. Using low multi-stage mass analyses of deuterated and non deuterated compounds, high-resolution mass analyses (Time of Flight, TOF) and other techniques, this novel compound was characterized as palythine–threonine. Palythine–threonine was also present in high concentrations in the Corals Pocillopora eydouxi and Stylophora pistillata indicating a wider distribution of this MAA among reef-building Corals. From structural considerations we suggest that palythine–threonine is formed by decarboxylation of porphyra-334 followed by demethylation of mycosporine–methylamine–threonine.
Hiroshi Ishibashi - One of the best experts on this subject based on the ideXlab platform.
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succession of delayed fluorescence correlated with Coral bleaching in the Hermatypic Coral acropora tenuis
Marine Pollution Bulletin, 2020Co-Authors: Ichiro Takeuchi, Daisuke Takaichi, Masakazu Katsumata, Hiroshi IshibashiAbstract:Abstract We investigated Coral bleaching by monitoring colour changes and measuring the delayed fluorescence (DF) of symbiotic dinoflagellates in the Hermatypic Coral Acropora tenuis, exposed to 1.0 μg/L Irgarol 1051 (photosystem II herbicide) for 14 d. The Irgarol concentration corresponded to those from international port regions of the world. The Coral colour and DFs under the control treatment were stable throughout the experiment, whereas under the Irgarol treatment the Corals showed gradual bleaching. The Irgarol treatment caused a rapid decrease in the slow decay DF component (10.1–60.0 s), while the fast decay DF component (0.1–10.0 s) decreased significantly after 6 d. The significant correlation between the latter values and the Coral colour indicates that if the electron accumulation function of quinones QA and QB is compromised, Corals will bleach. The present study will contribute to the understanding of the mechanism involved in bleaching of Coral exposed to herbicides.
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effects of ecologically relevant concentrations of irgarol 1051 in tropical to subtropical coastal seawater on Hermatypic Coral acropora tenuis and its symbiotic dinoflagellates
Marine Pollution Bulletin, 2020Co-Authors: Misato Kamei, Hiroshi Ishibashi, Kotaro Takayama, Ichiro TakeuchiAbstract:Abstract The effects of ecologically relevant concentrations of Irgarol 1051, a representative PSII herbicide, on Hermatypic Corals were studied in the laboratory. The colour and chlorophyll fluorescence of Acropora tenuis were examined following exposure to around ambient concentrations of Irgarol 1051 (20 ng/L and 200 ng/L) for 7 days. While the colour of Corals was stable throughout the experiment at both concentrations, the maximum effective quantum yield (ΔF/Fm′) of symbiotic dinoflagellates decreased with increasing Irgarol 1051 concentration (day 7: 8%, 20 ng/L; 37%, 200 ng/L). The expression of heat shock protein (HSP) 70 and 90 in symbiotic dinoflagellates was upregulated after 7 days exposure to both Irgarol concentrations, whereas HSP90 in Coral was not upregulated. The findings of the present study suggest that the threshold of chlorophyll fluorescence and HSP expression in symbiotic dinoflagellates is lower than 20 ng/L, which is around ecologically relevant concentrations in tropical to subtropical waters.