Why does the white tip of stony coral grow so fast without zooxanthellae?

Fang, Lee‐Shing; Chen, Y. w. J.; Chen, C. s.

doi:10.1007/bf00397270

Cited by 81 publications

(53 citation statements)

References 19 publications

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“…In line with previous studies, zooxanthellae were present only in very low numbers or absent in the pigmented colony tips or margins (Fang et al 1989;D'Angelo et al 2008). In the growth zones, the weak absorption of the incident light by the low amounts of photosynthetic zooxanthellae pigments results in an increased reflection by the skeleton.…”

Section: Gfp-like Proteinssupporting

confidence: 92%

Locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals as detected by green fluorescent protein (GFP)-like pigments

et al. 2012

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Homologs of the green fluorescent protein (GFP) are a prevalent group of host pigments responsible for the green, red and purple-blue colours of many reefbuilding corals. They have been suggested to contribute to the striking coloration changes of different corals species in response to wounding and infestation with epibionts/parasites. In order to elucidate the physiological processes underlying the potentially disease-related colour changes, we have analysed spatial and temporal expression patterns of GFP-like proteins and other biomarkers in corals from the Red Sea, the Arabian/Persian Gulf and Fiji both in their natural habitat and under specific laboratory conditions. The expression of distinct GFP-like proteins and the growth marker proliferating cell nuclear antigen was upregulated in growing branch tips and margins of healthy coral colonies as well as in disturbed colony parts. Furthermore, phenoloxidase activity increased in these proliferating tissues. It is thus demonstrated that locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals and, moreover, these processes can be detected utilizing the excellent biomarker properties of GFP-like proteins. Finally, the results of this work suggest an additional vulnerability of corals in predicted future scenarios of increased ocean acidification, warming and eutrophication that are anticipated to reduce coral growth capacity.

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Section: Gfp-like Proteinssupporting

confidence: 92%

Locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals as detected by green fluorescent protein (GFP)-like pigments

et al. 2012

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“…The observation of higher δ 11 B values for off-axis compared with the primary growth axis of the nubbins (Fig. S5) is unexpected because growth is higher along the primary growth axis, so we can only speculate that factor(s) other than direct pH cf controls on CO 3 2− , such as the internal transport of carbon and energy to sites of calcification (30) are driving faster axial growth rates.…”

Section: Resultsmentioning

confidence: 84%

pH homeostasis during coral calcification in a free ocean CO ₂ enrichment (FOCE) experiment, Heron Island reef flat, Great Barrier Reef

Georgiou

Falter

Trotter

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Geochemical analyses (δ 11 B and Sr/Ca) are reported for the coral Porites cylindrica grown within a free ocean carbon enrichment (FOCE) experiment, conducted on the Heron Island reef flat (Great Barrier Reef) for a 6-mo period from June to early December 2010. The FOCE experiment was designed to simulate the effects of CO 2 -driven acidification predicted to occur by the end of this century (scenario RCP4.5) while simultaneously maintaining the exposure of corals to natural variations in their environment under in situ conditions. Analyses of skeletal growth (measured from extension rates and skeletal density) showed no systematic differences between low-pH FOCE treatments (ΔpH = ∼−0.05 to −0.25 units below ambient) and present day controls (ΔpH = 0) for calcification rates or the pH of the calcifying fluid (pH cf ); the latter was derived from boron isotopic compositions (δ 11 B) of the coral skeleton. Furthermore, individual nubbins exhibited near constant δ 11 B compositions along their primary apical growth axes (±0.02 pH cf units) regardless of the season or treatment. Thus, under the highly dynamic conditions of the Heron Island reef flat, P. cylindrica up-regulated the pH of its calcifying fluid (pH cf ∼8.4-8.6), with each nubbin having nearconstant pH cf values independent of the large natural seasonal fluctuations of the reef flat waters (pH ∼7.7 to ∼8.3) or the superimposed FOCE treatments. This newly discovered phenomenon of pH homeostasis during calcification indicates that coral living in highly dynamic environments exert strong physiological controls on the carbonate chemistry of their calcifying fluid, implying a high degree of resilience to ocean acidification within the investigated ranges.A tmospheric CO 2 has risen by more than 30% during the last century, causing a reduction in seawater pH of ∼0.1 units relative to preindustrial times, with a further reduction of 0.1-0.4 units predicted to occur by the end of this century (1). This process, commonly known as "ocean acidification," is expected to have severe impacts on calcifying marine organisms due to its effect on the thermodynamics of biomineralization (2). Our current understanding of the sensitivity of coral calcification to declining seawater pH has mainly been inferred from short-term laboratory-based studies that do not fully simulate real-world reef conditions, particularly the daily to seasonal variations in temperature, light, and pH (3-5). To address these shortcomings, we applied free ocean carbon enrichment (FOCE) technologies (6-9) to manipulate water chemistry in situ and thereby provide more realistic experimental conditions to investigate how future levels of acidification could affect marine organisms according to different representative concentration pathways (RCPs) (10). The FOCE system uses a flowthrough flume design that allows organisms to experience near natural conditions, in particular the daily and seasonal regimes of fluctuating temperature, light, and nutrients while maintaining offsets in flume water pH below ...

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“…Individual colony bleaching patterns, which typically proceed from the tips or edges towards the base or centre (see e.g. Shenkar et al, 2005), also conform to the known colonyscale topology of MI, wherein the tips and edges consistently contain zooxanthellae with higher MI (Fang and Chen, 1989;Jones and Yellowlees, 1997). Indeed, Wooldridge (2009a) uses the ATP-dependent CO 2 -limitation model (Fig.…”

Section: Bleaching Thresholds Linked To Zooxanthellae MImentioning

confidence: 74%

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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Why does the white tip of stony coral grow so fast without zooxanthellae?

Cited by 81 publications

References 19 publications

Locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals as detected by green fluorescent protein (GFP)-like pigments

Locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals as detected by green fluorescent protein (GFP)-like pigments

pH homeostasis during coral calcification in a free ocean CO ₂ enrichment (FOCE) experiment, Heron Island reef flat, Great Barrier Reef

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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Why does the white tip of stony coral grow so fast without zooxanthellae?

Cited by 81 publications

References 19 publications

Locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals as detected by green fluorescent protein (GFP)-like pigments

Locally accelerated growth is part of the innate immune response and repair mechanisms in reef-building corals as detected by green fluorescent protein (GFP)-like pigments

pH homeostasis during coral calcification in a free ocean CO 2 enrichment (FOCE) experiment, Heron Island reef flat, Great Barrier Reef

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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pH homeostasis during coral calcification in a free ocean CO ₂ enrichment (FOCE) experiment, Heron Island reef flat, Great Barrier Reef