Spatial variation in porosity and skeletal element characteristics in apical tips of the branching coral Acropora pulchra (Brook 1891)


Micro-CT scanning techniques were used to investigate fine-scale variation in porosity along branch tips of Acropora pulchra. Porosity variation is a result of progressive thickening of skeletal elements away from the apical tip of branches, rather than changes in the spacing of skeletal elements. A linear fit was found to describe the relationship between distance along the tip and both porosity and skeletal thickness. The slope of the line obtained may relate to branch extension rates and allow retrospective data to be obtained from Acropora specimens. Skeletal morphology examined by 2D and 3D imaging shows a progressive gradation in thickness occurring in the axial corallite wall and thickness changes at a site of incipient branch formation. The application of the micro-CT technique to museum and fossil specimens is illustrated.

This is a preview of subscription content, log in to check access.

Access options

Buy single article

Instant unlimited access to the full article PDF.

US$ 39.95

Price includes VAT for USA

Subscribe to journal

Immediate online access to all issues from 2019. Subscription will auto renew annually.

US$ 199

This is the net price. Taxes to be calculated in checkout.

Fig. 1
Fig. 2
Fig. 3


  1. Barnes DJ, Devereux MJ (1988) Variations in skeletal architecture associated with density banding in the hard coral Porites. J Exp Mar Biol Ecol 121:37–54

  2. Beuck L, Vertino A, Stepina E, Karolczak M, Pfannkuche O (2007) Skeletal response of Lophelia pertusa (Scleractinia) to bioeroding sponge infestation visualised with micro-computed tomography. Facies 53:157–176

  3. Bottjer DJ (1980) Branching morphology of the reef coral Acropora cervicornis in different hydraulic regimes. J Paleontol 54:1102–1107

  4. Bucher DJ, Harriott VJ, Roberts LG (1998) Skeletal micro-density, porosity and bulk density of acroporid corals. J Exp Mar Biol Ecol 228:117–136

  5. Carricart-Ganivet JP, Lough JM, Barnes DJ (2007) Growth and luminescence characteristics in skeletons of massive Porites from a depth gradient in the central Great Barrier Reef. J Exp Mar Biol Ecol 351:27–36

  6. Chalker BE, Barnes DJ (1990) Gamma densitometry for the measurement of skeletal density Coral Reefs 9:11–23

  7. Cleveland RO, Cohen AL, Roy RA, Singh H, Szabo TL (2004) Imaging coral II: using ultrasound to image coral skeleton. Subsurf Sens Technol Appl 5:43–69

  8. Dodge RE, Vaisnys JR (1975) Hermatypic coral growth banding as environmental recorder. Nature 258:706–708

  9. Gladfelter EH (1982) Skeletal development in Acorpora cervicornis. Patterns of calcium carbonate accretion in the axial corallite. Coral Reefs 1:45–51

  10. Gladfelter EH (2007) Skeletal development in Acropora palmata (Lamarck 1816): a scanning electron microscope (SEM) comparison demonstrating similar mechanisms of skeletal extension in axial versus encrusting growth. Coral Reefs 26:883–892

  11. Kaniewska P, Campbell PR, Fine M, Hoegh-Guldberg O (2009) Phototrophic growth in a reef flat acroporid branching species. J Exp Biol 212:662–667

  12. Laine J, Labady M, Albornoz A, Yunes S (2008) Porosities and pore sizes in coralline calcium carbonate. Mater Charact 59:1522–1525

  13. Le Tissier MD, Clayton B, Brown BE, Davies PS (1994) Skeletal correlates of density banding and an evaluation of radiography as used in sclerochronology. Mar Ecol Prog Ser 110:29–44

  14. McColl DJ, Abel RL, Spears IR, Macho GA (2006) Automated method to measure trabecular thickness from micro-computed tomographic scans and its application. Anat Rec A Discov Mol Cell Evol Biol 288:982–988

  15. Oliver JK (1984) Intra-colony variation in the growth of Acropora formosa: Extension rates and skeletal structure of white (zooxanthellae-free) and brown-tipped Branches. Coral Reefs 3:139–147

  16. Saenger C, Cohen AL, Oppo DW, Halley RB, Carilli JE (2008) Surface-temperature trends and variability in the low-latitude North Atlantic since 1552. Nature Geoscience. doi:101038/NGEO552

  17. Schönberg CHL (2001) Estimating the extent of endolithic tissue of a great barrier reef clionid sponge. Marine Biodiversity 31:29–39

  18. Shirai K, Kawashima T, Sowa K, Watanabe T, Nakamori T, Takahata N, Amakawa H, Sano Y (2008) Minor and trace element incorporation into branching coral Acropora nobilis skeleton. Geochim Cosmochim Acta 72:5386–5400

  19. Wallace CC, Willis BL (1994) Systematics of the coral genus Acropora: implications of new biological findings for species concepts. Annu Rev Ecol Syst 25:237–262

  20. Wellington GM, Glynn PW (1983) Environmental influences on skeletal banding in eastern Pacific (Panama) corals. Coral Reefs 1:215–222

Download references


Support for this research was provided by a UK Natural Environmental Research Council Grant NE/F01077X/1 to CTP and KGJ. Acropora pulchra specimens were collected under GBRMPA research permit number G08/27113.1.

Author information

Correspondence to R. C. Roche.

Additional information

Communicated by Geology Editor Prof. Bernhard Riegl

Electronic supplementary material

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Roche, R.C., Abel, R.L., Johnson, K.G. et al. Spatial variation in porosity and skeletal element characteristics in apical tips of the branching coral Acropora pulchra (Brook 1891). Coral Reefs 30, 195–201 (2011).

Download citation


  • Acropora
  • Porosity
  • CT scan
  • Skeletal structure