Cooper et al. 2011

scientific article | Proc Biol Sci | open access Open access small aa108fa7f478951c693af64a05bc4b46e6711dbb69a20809512a129d4d6b870f

Niche specialization of reef-building corals in the mesophotic zone: metabolic trade-offs between divergent Symbiodinium types

Cooper TF, Ulstrup KE, Dandan SS, Heyward AJ, Kühl M, Muirhead A, O'Leary RA, Ziersen BEF, Van Oppen MJH

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The photobiology of two reef corals and the distribution of associated symbiont types were investigated over a depth gradient of 0-60 m at Scott Reef, Western Australia. Pachyseris speciosa hosted mainly the same Symbiodinium C type similar to C3 irrespective of sampling depth. By contrast, Seriatopora hystrix hosted predominantly Symbiodinium type D1a or D1a-like at shallow depths while those in deeper water were dominated by a Symbiodinium C type closely related to C1. The photosynthesis/respiration (P/R) ratio increased consistently with depth at the two sampling times (November 2008 and April 2009) for P. speciosa and in November 2008 only for S. hystrix, suggesting a reduction in metabolic energy expended for every unit of energy obtained from photosynthesis. However, in April 2009, shallow colonies of S. hystrix exhibited decreased P/R ratios down to depths of approximately 23 m, below which the ratio increased towards the maximum depth sampled. This pattern was mirrored by changes in tissue biomass determined as total protein content. The depth of change in the direction of the P/R ratio correlated with a shift from Symbiodinium D to C-dominated colonies. We conclude that while photobiological flexibility is vital for persistence in contrasting light regimes, a shift in Symbiodinium type may also confer a functional advantage albeit at a metabolic cost with increased depth.

Research sites

10.1098   rspb.2010.2321
Meta-data (pending validation)
Depth range
3- 60 m

Mesophotic “mentions”
12 x (total of 5336 words)

Physiology Molecular ecology Ecology

Research focus
Scleractinia (Hard Corals) Symbiodinium (zooxanthellae) Overall benthic (groups)

Australia - Scott Reef

Research platforms
Remotely Operated Vehicle (ROV) Dredging / trawling
Author profiles
Timothy Cooper ( 3 pubs)
Andrew Heyward ( 2 pubs)