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Morphological plasticity of the coral skeleton under CO2-driven seawater acidification.

Tambutté E, Venn AA, Holcomb M, Segonds N, Techer N, Zoccola D, Allemand D, Tambutté S - Nat Commun (2015)

Bottom Line: Ocean acidification causes corals to calcify at reduced rates, but current understanding of the underlying processes is limited.Instead, changes occur by enlargement of corallite-calyxes and thinning of associated skeletal elements, constituting a modification in skeleton architecture.We also detect increases in the organic matrix protein content of skeletons formed under lower pH.

View Article: PubMed Central - PubMed

Affiliation: 1] Marine Biology Department, Centre Scientifique de Monaco, 8 Quai Antoine 1er, Monaco 98000, Monaco [2] Laboratoire Européen Associé 647 « BIOSENSIB », Centre Scientifique de Monaco- Centre National de la Recherche Scientifique, 8 Quai Antoine 1er, Monaco 98000, Monaco.

ABSTRACT
Ocean acidification causes corals to calcify at reduced rates, but current understanding of the underlying processes is limited. Here, we conduct a mechanistic study into how seawater acidification alters skeletal growth of the coral Stylophora pistillata. Reductions in colony calcification rates are manifested as increases in skeletal porosity at lower pH, while linear extension of skeletons remains unchanged. Inspection of the microstructure of skeletons and measurements of pH at the site of calcification indicate that dissolution is not responsible for changes in skeletal porosity. Instead, changes occur by enlargement of corallite-calyxes and thinning of associated skeletal elements, constituting a modification in skeleton architecture. We also detect increases in the organic matrix protein content of skeletons formed under lower pH. Overall, our study reveals that seawater acidification not only causes decreases in calcification, but can also cause morphological change of the coral skeleton to a more porous and potentially fragile phenotype.

No MeSH data available.


Related in: MedlinePlus

Skeletal growth parameters in the four pH treatments.(a) Net calcification rate (one way ANOVA, n=12, F3,44=4.11, P<0.05). (b) Linear extension (one way ANOVA, n=15, F3,56=0.62, P>0.05). (c) Bulk skeletal density (one way ANOVA, n=7, F3,24=16.44, P<0.001). (d) Skeletal porosity (one way ANOVA, n=3, F 3,8=11.05, P<0.05). Data are means±s.e.m. Asterisk (*) indicates values that are significantly different for treatment with pH 8 (P<0.05).
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f1: Skeletal growth parameters in the four pH treatments.(a) Net calcification rate (one way ANOVA, n=12, F3,44=4.11, P<0.05). (b) Linear extension (one way ANOVA, n=15, F3,56=0.62, P>0.05). (c) Bulk skeletal density (one way ANOVA, n=7, F3,24=16.44, P<0.001). (d) Skeletal porosity (one way ANOVA, n=3, F 3,8=11.05, P<0.05). Data are means±s.e.m. Asterisk (*) indicates values that are significantly different for treatment with pH 8 (P<0.05).

Mentions: Throughout the investigation, coral colonies remained visibly healthy (polyps remained extended and corals unbleached), and calcified in all experimental pH treatments, including treatment pH 7.2 (Ωaragonite<1)(carbonate chemistry of treatments given in Table 1). Respiration and photosynthetic rates of coral colonies remained unchanged across experimental treatments, with respiration rates higher than net photosynthetic rates in all treatments (Table 2). As anticipated, rates of calcification declined under seawater acidification, with significant decreases measured at pH 7.4 and 7.2 relative to calcification at pH 8 (Fig. 1a). By contrast, rates of linear extension of corals did not change significantly across pH treatments (Fig. 1b). Instead, skeletal bulk density decreased significantly at low pH (Fig. 1c) and quantitative x-ray micro-computed tomography CT (micro-CT) analysis revealed an increase in skeletal porosity at pH 7.4 and 7.2 relative to pH 8 (Fig. 1d). Together, these data show that declines in calcification rate are manifested in a change in skeletal density and porosity, and not in extension rates of the skeleton.


Morphological plasticity of the coral skeleton under CO2-driven seawater acidification.

Tambutté E, Venn AA, Holcomb M, Segonds N, Techer N, Zoccola D, Allemand D, Tambutté S - Nat Commun (2015)

Skeletal growth parameters in the four pH treatments.(a) Net calcification rate (one way ANOVA, n=12, F3,44=4.11, P<0.05). (b) Linear extension (one way ANOVA, n=15, F3,56=0.62, P>0.05). (c) Bulk skeletal density (one way ANOVA, n=7, F3,24=16.44, P<0.001). (d) Skeletal porosity (one way ANOVA, n=3, F 3,8=11.05, P<0.05). Data are means±s.e.m. Asterisk (*) indicates values that are significantly different for treatment with pH 8 (P<0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490415&req=5

f1: Skeletal growth parameters in the four pH treatments.(a) Net calcification rate (one way ANOVA, n=12, F3,44=4.11, P<0.05). (b) Linear extension (one way ANOVA, n=15, F3,56=0.62, P>0.05). (c) Bulk skeletal density (one way ANOVA, n=7, F3,24=16.44, P<0.001). (d) Skeletal porosity (one way ANOVA, n=3, F 3,8=11.05, P<0.05). Data are means±s.e.m. Asterisk (*) indicates values that are significantly different for treatment with pH 8 (P<0.05).
Mentions: Throughout the investigation, coral colonies remained visibly healthy (polyps remained extended and corals unbleached), and calcified in all experimental pH treatments, including treatment pH 7.2 (Ωaragonite<1)(carbonate chemistry of treatments given in Table 1). Respiration and photosynthetic rates of coral colonies remained unchanged across experimental treatments, with respiration rates higher than net photosynthetic rates in all treatments (Table 2). As anticipated, rates of calcification declined under seawater acidification, with significant decreases measured at pH 7.4 and 7.2 relative to calcification at pH 8 (Fig. 1a). By contrast, rates of linear extension of corals did not change significantly across pH treatments (Fig. 1b). Instead, skeletal bulk density decreased significantly at low pH (Fig. 1c) and quantitative x-ray micro-computed tomography CT (micro-CT) analysis revealed an increase in skeletal porosity at pH 7.4 and 7.2 relative to pH 8 (Fig. 1d). Together, these data show that declines in calcification rate are manifested in a change in skeletal density and porosity, and not in extension rates of the skeleton.

Bottom Line: Ocean acidification causes corals to calcify at reduced rates, but current understanding of the underlying processes is limited.Instead, changes occur by enlargement of corallite-calyxes and thinning of associated skeletal elements, constituting a modification in skeleton architecture.We also detect increases in the organic matrix protein content of skeletons formed under lower pH.

View Article: PubMed Central - PubMed

Affiliation: 1] Marine Biology Department, Centre Scientifique de Monaco, 8 Quai Antoine 1er, Monaco 98000, Monaco [2] Laboratoire Européen Associé 647 « BIOSENSIB », Centre Scientifique de Monaco- Centre National de la Recherche Scientifique, 8 Quai Antoine 1er, Monaco 98000, Monaco.

ABSTRACT
Ocean acidification causes corals to calcify at reduced rates, but current understanding of the underlying processes is limited. Here, we conduct a mechanistic study into how seawater acidification alters skeletal growth of the coral Stylophora pistillata. Reductions in colony calcification rates are manifested as increases in skeletal porosity at lower pH, while linear extension of skeletons remains unchanged. Inspection of the microstructure of skeletons and measurements of pH at the site of calcification indicate that dissolution is not responsible for changes in skeletal porosity. Instead, changes occur by enlargement of corallite-calyxes and thinning of associated skeletal elements, constituting a modification in skeleton architecture. We also detect increases in the organic matrix protein content of skeletons formed under lower pH. Overall, our study reveals that seawater acidification not only causes decreases in calcification, but can also cause morphological change of the coral skeleton to a more porous and potentially fragile phenotype.

No MeSH data available.


Related in: MedlinePlus