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Light respiratory processes and gross photosynthesis in two scleractinian corals.

Schrameyer V, Wangpraseurt D, Hill R, Kühl M, Larkum AW, Ralph PJ - PLoS ONE (2014)

Bottom Line: Light respiration in Pocillopora damicornis was higher than in Pavona decussata under low irradiance, indicating species-specific differences in light-dependent metabolic processes.Overall, the coral P. decussata exhibited higher CO2 uptake rates than P. damicornis over the experimental irradiance range.Differences in light respiration and CO2 availability could be due to host-specific characteristics that modulate the symbiont microenvironment, its photosynthesis, and hence the overall performance of the coral holobiont.

View Article: PubMed Central - PubMed

Affiliation: Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology, Sydney, Ultimo, New South Wales, Australia.

ABSTRACT
The light dependency of respiratory activity of two scleractinian corals was examined using O2 microsensors and CO2 exchange measurements. Light respiration increased strongly but asymptotically with elevated irradiance in both species. Light respiration in Pocillopora damicornis was higher than in Pavona decussata under low irradiance, indicating species-specific differences in light-dependent metabolic processes. Overall, the coral P. decussata exhibited higher CO2 uptake rates than P. damicornis over the experimental irradiance range. P. decussata also harboured twice as many algal symbionts and higher total protein biomass compared to P. damicornis, possibly resulting in self-shading of the symbionts and/or changes in host tissue specific light distribution. Differences in light respiration and CO2 availability could be due to host-specific characteristics that modulate the symbiont microenvironment, its photosynthesis, and hence the overall performance of the coral holobiont.

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Variation in gas exchange measurements with irradiance.The graphs display gross CO2 exchange (GCO2 PBR; black circles; CO2 nmol cm−2 s−1) and microsensor derived gross photosynthetic O2 production (GPO2 micro; open circles; O2 nmol cm−2 s−1) of the hard coral species Pocillopora damicornis (A) and Pavona decussata (B) as a function of nine irradiances (mean ±s.e.m.; GCO2 PBR: n = 4 and GPO2 micro: n = 2); Tukey honest significant difference test results are indicated for GCO2 PBR (lower case letters) and GPO2 micro (capitals) (p<0.05).
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pone-0110814-g001: Variation in gas exchange measurements with irradiance.The graphs display gross CO2 exchange (GCO2 PBR; black circles; CO2 nmol cm−2 s−1) and microsensor derived gross photosynthetic O2 production (GPO2 micro; open circles; O2 nmol cm−2 s−1) of the hard coral species Pocillopora damicornis (A) and Pavona decussata (B) as a function of nine irradiances (mean ±s.e.m.; GCO2 PBR: n = 4 and GPO2 micro: n = 2); Tukey honest significant difference test results are indicated for GCO2 PBR (lower case letters) and GPO2 micro (capitals) (p<0.05).

Mentions: For P. damicornis, gross CO2 uptake from the seawater declined up to an irradiance of 78 µmol photons m−2 s−1 (one-way ANOVA, F (8, 27)  = 2.90, p = 0.018; Fig. 1 A), and then increased slightly up to an irradiance of 560 µmol photons m−2 s−1 followed by a small but significant decline at irradiances of 780 and 1100 µmol photons m−2 s−1 (Tukey HSD, p<0.05; Fig. 1 A, also see Table S1). In contrast, gross CO2 uptake of P. decussata showed no decline in the first phase of illumination (10 and 20 µmol photons m−2 s−1). Gross CO2 uptake increased from an irradiance of 40 up to 78 µmol photons m−2 s−1 and then remained steady besides a dip at an irradiance of 560 µmol photons m−2 s−1 (Fig. 1 B). The metabolic activity differed most significantly between the two species under low irradiance (pooled CO2 rates for irradiances of 10–40 µmol photons m−2 s−1; t (22)  = 3.54, p<0.001; Figs. 1 A and B, also see Table S1).


Light respiratory processes and gross photosynthesis in two scleractinian corals.

Schrameyer V, Wangpraseurt D, Hill R, Kühl M, Larkum AW, Ralph PJ - PLoS ONE (2014)

Variation in gas exchange measurements with irradiance.The graphs display gross CO2 exchange (GCO2 PBR; black circles; CO2 nmol cm−2 s−1) and microsensor derived gross photosynthetic O2 production (GPO2 micro; open circles; O2 nmol cm−2 s−1) of the hard coral species Pocillopora damicornis (A) and Pavona decussata (B) as a function of nine irradiances (mean ±s.e.m.; GCO2 PBR: n = 4 and GPO2 micro: n = 2); Tukey honest significant difference test results are indicated for GCO2 PBR (lower case letters) and GPO2 micro (capitals) (p<0.05).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4216011&req=5

pone-0110814-g001: Variation in gas exchange measurements with irradiance.The graphs display gross CO2 exchange (GCO2 PBR; black circles; CO2 nmol cm−2 s−1) and microsensor derived gross photosynthetic O2 production (GPO2 micro; open circles; O2 nmol cm−2 s−1) of the hard coral species Pocillopora damicornis (A) and Pavona decussata (B) as a function of nine irradiances (mean ±s.e.m.; GCO2 PBR: n = 4 and GPO2 micro: n = 2); Tukey honest significant difference test results are indicated for GCO2 PBR (lower case letters) and GPO2 micro (capitals) (p<0.05).
Mentions: For P. damicornis, gross CO2 uptake from the seawater declined up to an irradiance of 78 µmol photons m−2 s−1 (one-way ANOVA, F (8, 27)  = 2.90, p = 0.018; Fig. 1 A), and then increased slightly up to an irradiance of 560 µmol photons m−2 s−1 followed by a small but significant decline at irradiances of 780 and 1100 µmol photons m−2 s−1 (Tukey HSD, p<0.05; Fig. 1 A, also see Table S1). In contrast, gross CO2 uptake of P. decussata showed no decline in the first phase of illumination (10 and 20 µmol photons m−2 s−1). Gross CO2 uptake increased from an irradiance of 40 up to 78 µmol photons m−2 s−1 and then remained steady besides a dip at an irradiance of 560 µmol photons m−2 s−1 (Fig. 1 B). The metabolic activity differed most significantly between the two species under low irradiance (pooled CO2 rates for irradiances of 10–40 µmol photons m−2 s−1; t (22)  = 3.54, p<0.001; Figs. 1 A and B, also see Table S1).

Bottom Line: Light respiration in Pocillopora damicornis was higher than in Pavona decussata under low irradiance, indicating species-specific differences in light-dependent metabolic processes.Overall, the coral P. decussata exhibited higher CO2 uptake rates than P. damicornis over the experimental irradiance range.Differences in light respiration and CO2 availability could be due to host-specific characteristics that modulate the symbiont microenvironment, its photosynthesis, and hence the overall performance of the coral holobiont.

View Article: PubMed Central - PubMed

Affiliation: Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology, Sydney, Ultimo, New South Wales, Australia.

ABSTRACT
The light dependency of respiratory activity of two scleractinian corals was examined using O2 microsensors and CO2 exchange measurements. Light respiration increased strongly but asymptotically with elevated irradiance in both species. Light respiration in Pocillopora damicornis was higher than in Pavona decussata under low irradiance, indicating species-specific differences in light-dependent metabolic processes. Overall, the coral P. decussata exhibited higher CO2 uptake rates than P. damicornis over the experimental irradiance range. P. decussata also harboured twice as many algal symbionts and higher total protein biomass compared to P. damicornis, possibly resulting in self-shading of the symbionts and/or changes in host tissue specific light distribution. Differences in light respiration and CO2 availability could be due to host-specific characteristics that modulate the symbiont microenvironment, its photosynthesis, and hence the overall performance of the coral holobiont.

Show MeSH