VARIABILITY IN THE PRIMARY SITE OF PHOTOSYNTHETIC DAMAGE IN <i>SYMBIODINIUM</i> SP. (DINOPHYCEAE) EXPOSED TO THERMAL STRESS<sup>1</sup>

Buxton, Lucy; Takahashi, Shunichi; Hill, Ross; Ralph, Peter J.

doi:10.1111/j.1529-8817.2011.01099.x

Cited by 53 publications

(35 citation statements)

References 36 publications

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“…Finally, the critical temperatures affecting thylakoid integrity, which determine irreversible changes in photosynthetic function, were examined. Such damage has been observed in coral algal symbionts (Buxton et al, 2012;Fitt et al, 2001;Tchernov et al, 2004). Determining critical temperatures could help in identifying tipping points where small changes in the environment cause rapid and extensive changes in an ecosystem (Clark et al, 2013;Scheffer et al, 2001).…”

Section: Introductionmentioning

confidence: 98%

Can bottom ice algae tolerate irradiance and temperature changes?

Rajanahally

Sim

Ryan

et al. 2014

Journal of Experimental Marine Biology and Ecology

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Sea ice algae are significant primary producers of the ice-covered marine environment, growing under typically cold, dim conditions. During ice break-up they are released to the water column, where temperatures can be several degrees higher and irradiance can increase by orders of magnitude. To determine how sea ice algae respond to such rapid changes, we carried out incubations to examine their tolerance to environmentally realistic levels of change in temperature and PAR, as expressed by photosynthetic response and production of mycosporine-like amino acids (MAAs). The algae were also exposed to a broader range of temperatures, to evaluate their potential to function in warmer seas in the event, for instance, of anthropogenic transfer to locations further north. When subjected to PAR (0-100 μmol m −2 s −1 ) at ecologically relevant temperatures (− 1°C, 2°C, 5°C), the algae showed tolerance, indicated by a lack of decline in the quantum efficiency of photosystem II (PSII). The data show that bottom ice algae can tolerate increasing temperature and PAR comparable to the changes experienced during and after sea ice melt. MAA production increased at higher PAR and temperature. At ambient PAR levels, increased temperatures resulted in lower ϕ PSII . However, as PAR levels were increased, higher temperature reduced the level of stress as indicated by higher ϕ PSII values. This result suggests, for the first time in sea ice algal studies, that higher temperatures can ameliorate the negative effects of increased PAR. Exposure to much higher temperatures suggested that the algae were capable of retaining some photosynthetic function at water temperatures well above those currently experienced in some of their Antarctic habitats. However, when temperature was gradually increased past 14°C, the photosystems started to become inactivated as indicated by a decrease in quantum yield, suggesting that the algae would not be viable if transferred to lower latitude cold temperate areas.

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Section: Introductionmentioning

confidence: 98%

Can bottom ice algae tolerate irradiance and temperature changes?

Rajanahally

Sim

Ryan

et al. 2014

Journal of Experimental Marine Biology and Ecology

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“…contain clade D symbionts (T. L. Goulet, personal communication) [note the contrast to Sarcothelia edmondsoni, which contain clade C symbionts (Goulet et al, 2008)]. Evidence suggests that some symbiont types are more sensitive to perturbation (Rowan et al, 1997;Buxton et al, 2012). Certainly, colonies of Sarcothelia sp.…”

Section: While No Increase In Ros Was Detected From 1 H To 7 H (A) Amentioning

confidence: 99%

“…Impairment of photosynthesis is typically associated with bleaching of corals (Jones et al, 1998;Tchernov et al, 2004;Buxton et al, 2012). During symbiont migration, colonies of Sarcothelia sp.…”

Section: Research Articlementioning

confidence: 99%

Physiological correlates of symbiont migration during bleaching of two octocoral species

Netherton

Scheer

Morrison

et al. 2014

Journal of Experimental Biology

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Perturbed colonies of Phenganax parrini and Sarcothelia sp. exhibit migration of symbionts of Symbiodinium spp. into the stolons. Densitometry and visual inspection indicated that polyps bleached while stolons did not. When migration was triggered by temperature, light and confinement, colonies of Sarcothelia sp. decreased rates of oxygen formation in the light (due to the effects of perturbation on photosynthesis and respiration) and increased rates of oxygen uptake in the dark (due to the effects of perturbation on respiration alone). Colonies of P. parrini, by contrast, showed no significant changes in either aspect of oxygen metabolism. When migration was triggered by light and confinement, colonies of Sarcothelia sp. showed decreased rates of oxygen formation in the light and increased rates of oxygen uptake in the dark, while colonies of P. parrini maintained the former and increased the latter. During symbiont migration into their stolons, colonies of both species showed dramatic increases in reactive oxygen species (ROS), as visualized with a fluorescent probe, with stolons of Sarcothelia sp. exhibiting a nearly immediate increase of ROS. Differences in symbiont type may explain the greater sensitivity of colonies of Sarcothelia sp. Using fluorescent probes, direct measurements of migrating symbionts in the stolons of Sarcothelia sp. showed higher levels of reactive nitrogen species and lower levels of ROS than the surrounding host tissue. As measured by native fluorescence, levels of NAD(P)H in the stolons were unaffected by perturbation. Symbiont migration thus correlates with dramatic physiological changes and may serve as a marker for coral condition.

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“…The fact that the majority of expelled zooxanthellae from thermally stressed corals remain photosynthetically competent (Ralph et al, 2001;Bhagooli and Hidaka, 2004) highlights the possibility that it may be a secondary response. Similarly, there is a growing body of evidence to indicate that dysfunction within the "dark reactions" of photosynthesis often precedes the photoinhibition bleaching response (Jones et al, 1998;Buxton et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Breakdown of the coral-algae symbiosis: towards formalising a linkage between warm-water bleaching thresholds and the growth rate of the intracellular zooxanthellae

Wooldridge

2013

Biogeosciences

130

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Impairment of the photosynthetic machinery of the algal endosymbiont ("zooxanthellae") is the proximal driver of the thermal breakdown of the coral-algae symbiosis ("coral bleaching"). Yet, the initial site of damage, and early dynamics of the impairment are still not well resolved. In this perspective essay, I consider further a recent hypothesis which proposes an energetic disruption to the carbon-concentrating mechanisms (CCMs) of the coral host, and the resultant onset of CO₂-limitation within the photosynthetic "dark reactions" as a unifying cellular mechanism. The hypothesis identifies the enhanced retention of photosynthetic carbon for zooxanthellae (re)growth following an initial irradiance-driven expulsion event as a strong contributing cause of the energetic disruption. If true, then it implies that the onset of the bleaching syndrome and setting of upper thermal bleaching limits are emergent attributes of the coral symbiosis that are ultimately underpinned by the characteristic growth profile of the intracellular zooxanthellae; which is known to depend not just on temperature, but also external (seawater) nutrient availability and zooxanthellae genotype. Here, I review this proposed bleaching linkage at a variety of observational scales, and find it to be parsimonious with the available evidence. Future experiments are suggested that can more formally test the linkage. If correct, the new cellular model delivers a valuable new perspective to consider the future prospects of the coral symbiosis in an era of rapid environmental change, including: (i) the underpinning mechanics (and biological significance) of observed changes in resident zooxanthellae genotypes, and (ii) the now crucial importance of reef water quality in co-determining thermal bleaching resistance

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VARIABILITY IN THE PRIMARY SITE OF PHOTOSYNTHETIC DAMAGE IN SYMBIODINIUM SP. (DINOPHYCEAE) EXPOSED TO THERMAL STRESS¹

Cited by 53 publications

References 36 publications

Can bottom ice algae tolerate irradiance and temperature changes?

Can bottom ice algae tolerate irradiance and temperature changes?

Physiological correlates of symbiont migration during bleaching of two octocoral species

Breakdown of the coral-algae symbiosis: towards formalising a linkage between warm-water bleaching thresholds and the growth rate of the intracellular zooxanthellae

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VARIABILITY IN THE PRIMARY SITE OF PHOTOSYNTHETIC DAMAGE IN SYMBIODINIUM SP. (DINOPHYCEAE) EXPOSED TO THERMAL STRESS1

Cited by 53 publications

References 36 publications

Can bottom ice algae tolerate irradiance and temperature changes?

Can bottom ice algae tolerate irradiance and temperature changes?

Physiological correlates of symbiont migration during bleaching of two octocoral species

Breakdown of the coral-algae symbiosis: towards formalising a linkage between warm-water bleaching thresholds and the growth rate of the intracellular zooxanthellae

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VARIABILITY IN THE PRIMARY SITE OF PHOTOSYNTHETIC DAMAGE IN SYMBIODINIUM SP. (DINOPHYCEAE) EXPOSED TO THERMAL STRESS¹