Diurnal changes in photochemical efficiency and xanthophyll concentrations in shallow water reef corals : evidence for photoinhibition and photoprotection

Brown, Barbara E.; Ambarsari, I.; Warner, Mark E.; Fitt, William K.; Dunne, R. P.; Gibb, Stuart W.; Cummings, Denise

doi:10.1007/s003380050163

Cited by 216 publications

(42 citation statements)

References 25 publications

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“…Over 2-3 month exposures to diuron, chronic effects on three coral species included reduced reproductive output (related to energy limitation), bleaching, and mortality (possibly related to chronic photoinhibition) (Cantin et al 2007). In the present study, additive and synergistic effects on F v : F m are of most concern, since this parameter indicates chronic photoinhibition (Brown et al 1999) and is significantly correlated to bleaching (Fig. 6).…”

Section: Discussionmentioning

confidence: 68%

Herbicides increase the vulnerability of corals to rising sea surface temperature

Negri

Flores

Röthig

et al. 2011

Limnology & Oceanography

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In order to examine the potential interactive pressures of local pollution and global climate change, we exposed corals and crustose coralline algae (CCA) to three agricultural photosystem II (PSII) herbicides at four temperatures (26-32uC). The coral Acropora millepora was 3-to 10-fold more sensitive to the three herbicides than the CCA Neogoniolithon fosliei. While the photosynthesis of CCA was not affected by the herbicide concentrations used (, 1 mg L 21 ), temperatures of 31uC and 32uC alone significantly inhibited photosynthetic efficiency (DF : F 9 m ) and caused chronic photoinhibition (reduced F v : F m ) and substantial bleaching. Environmentally relevant concentrations of each herbicide increased the negative effects of thermal stress on coral at 31uC and 32uC. Mixed model analyses of variance showed that the effects of elevated sea surface temperatures (SST) and herbicide on photosynthetic efficiency of coral symbionts were additive. Furthermore, the effect of either diuron or atrazine in combination with higher SST (31uC and 32uC) on chronic photoinhibition was distinctly greater than additive (synergistic). Reducing the herbicide concentration by 1 mg L 21 diuron above 30uC would protect photosynthetic efficiency by the equivalent of 1.8uC and reduce chronic photoinhibition by the equivalent of a 1uC reduction. Reduced water quality increases the vulnerability of corals to elevated SSTs, and effective management of local water quality can reduce negative effects of global stressors such as elevated SST.

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Section: Discussionmentioning

confidence: 68%

Herbicides increase the vulnerability of corals to rising sea surface temperature

Negri

Flores

Röthig

et al. 2011

Limnology & Oceanography

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“…For instance, the higher PP xanthophyll de-epoxidation in Symbiodinium type C15 may facilitate the occurrence of Porites even in very shallow water where they are exposed to light intensities that can potentially impair the photosynthetic apparatus (Brown et al, 1999). This advantage may offset the overall lower maximum photosynthetic yield of Symbiodinium type C15.…”

Section: Coral-symbiodinium Depth Structure and Partitioningmentioning

confidence: 99%

“…Porites has a broad bathymetric distribution and this is reflected by Symbiodinium type C15 that showed a strong photoacclimatory signal. For instance, a negative correlation of ddx to chl a with depth indicates that PP pathways are downregulated when light is scarce (Frank and Cogdell, 1996;Brown et al, 1999). At the same time, the LH potential in deeper water was increased by harboring more cellular chl a along with increasing ß-carotene to chl a ratios (MacIntyre et al, 2002).…”

Section: Coral-symbiodinium Depth Structure and Partitioningmentioning

confidence: 99%

“…The major LH pigments are chlorophyll a (chl a), chlorophyll c 2 (chl c 2 ), and peridinin (per) that build different protein complexes to harvest available light energy (Iglesias-Prieto and Trench, 1997). Diadinoxanthin (ddx) and diatoxanthin (dtx) are components of the xanthophyll cycle in dinoflagellates, and together with ß-carotene (ß-car) comprise the PP pigments (Jeffrey and Haxo, 1968;Brown et al, 1999). ß-carotene is found in both photosystems together with chl a where it mainly acts as a sink for excess light energy, but also aids in stabilizing the photosystem structure (Kirk, 1994;Frank and Cogdell, 1996;Fromme et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Mesophotic coral depth acclimatization is a function of host-specific symbiont physiology

et al. 2015

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Mesophotic coral ecosystems receive increasing attention owing to their potential as deep coral refuges in times of global environmental change. Here, the mechanisms of coral holobiont photoacclimatization over a 60 m depth gradient in the central Red Sea were examined for the four coral genera Porites, Leptoseris, Pachyseris, and Podabacia. General acclimatization strategies were common to all host-symbiont combinations, e.g., Symbiodinium cell densities and photoprotective (PP) to light-harvesting pigment ratios both significantly decreased with water depth. Porites harbored Symbiodinium type C15 over the whole 60 m depth range, while Pachyseris and Podabacia had limited vertical distributions and hosted mainly Symbiodinium type C1. Symbiodinium type C15 had generally higher xanthophyll de-epoxidation rates and lower maximum quantum yields than C1, and also exhibited a strong photoacclimatory signal over depth that relates to the large distribution range of Porites. Interestingly, the coral host had an effect on Symbiodinium pigment composition. When comparing Symbiodinium type C1 in Podabacia and Pachyseris, the ß-carotene chl a −1 , the peridinin chl a −1 , and diadinoxanthin chl a −1 ratios were significantly different between host species. Our data support a view that depth acclimatization of corals in the mesophotics is facilitated by Symbiodinium physiology, which in turn is host-specific.

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“…NPQ has a finite capacity and may reach saturation while excess electrons continue to reduce the electron transport chain (Brown et al, 1999;Dustan, 1999;Smith et al, 2005). Alternative sinks for electrons, other than CO 2 assimilation, may provide additional protection mechanisms to help prevent over reduction at high light intensities.…”

Section: Introductionmentioning

confidence: 99%

Novel Adaptive Photosynthetic Characteristics of Mesophotic Symbiotic Microalgae within the Reef-Building Coral, Stylophora pistillata

et al. 2016

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Photosynthetic coral reef structures extend from the shallow sundrenched waters to the dimly lit, "twilight" mesophotic depths. For their resident endosymbiotic dinoflagellates, primarily from the genus Symbiodinium spp., this represents a photic environment that varies ∼15-fold in intensity and also differs in spectral composition. We examined photosynthesis in the scleractinian coral Stylophora pistillata in shallow (3 m) and mesophotic settings (65 m) in the northern Red Sea. Symbiodinium spp. in corals originating from the mesophotic environment consistently performed below their photosynthetic compensation point and also exhibited distinct light harvesting antenna organization. In addition, the non-photochemical quenching activity of Symbiodinium spp. from mesophotic corals was shown to be considerably lower than those found in shallow corals, showing they have fewer defenses to high-light settings. Over a period of almost 4 years, we extensively utilized closed circuit Trimix rebreather diving to perform the study. Phylogenetic analysis showed that shallow corals (3 m) transplanted to a deep reef environment (65 m) maintained their initial Symbiodinium spp. community (clade A), rather than taking on deep low-light clades (clade C), demonstrating that shallow S. pistillata acclimate to low-light mesophotic environments while maintaining their shallow photosynthetic traits. Mesophotic corals exhibited static depth-related chlorophyll content per cell, a decrease in PSI activity and enhanced sigmoidal fluorescence rise kinetics. The sigmoidal fluorescence rise kinetics we observed in mesophotic corals is an indication of energy transfer between photosynthetic units. We postulate that at mesophotic depths, a community of adapted Symbiodinium spp. utilize a unique adaptation to lower light conditions by shifting their light harvesting to a PSII based system, where PSII is structured near PSI, with additional PCP soluble Einbinder et al.Novel Photosynthetic Characteristics of Mesophotic Photosymbionts antenna also trapping light that is funneled to the PSI reaction center. In this study, we provide evidence that mesophotic Symbiodinium spp. have developed novel adaptive low-light characteristics consisting of a cooperative system for excitation energy transfer between photosynthetic units that maximizes light utilization.

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Diurnal changes in photochemical efficiency and xanthophyll concentrations in shallow water reef corals : evidence for photoinhibition and photoprotection

Cited by 216 publications

References 25 publications

Herbicides increase the vulnerability of corals to rising sea surface temperature

Herbicides increase the vulnerability of corals to rising sea surface temperature

Mesophotic coral depth acclimatization is a function of host-specific symbiont physiology

Novel Adaptive Photosynthetic Characteristics of Mesophotic Symbiotic Microalgae within the Reef-Building Coral, Stylophora pistillata

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