TY - JOUR

T1 - Niche specialization of reef-building corals in the mesophotic zone

T2 - metabolic trade-offs between divergent Symbiodinium types

AU - Cooper, Timothy F.

AU - Ulstrup, Karin Elizabeth

AU - Dandan, Sana S.

AU - Heyward, Andrew J.

AU - Kühl, Michael

AU - Muirhead, Andrew

AU - O'Leary, Rebecca A.

AU - Ziersen, Bibi Emilie Friis

AU - van Oppen, Madeleine J. H.

PY - 2011

Y1 - 2011

N2 - The photobiology of two reef corals and the distribution of associated symbiont types were investigatedover a depth gradient of 0–60 m at Scott Reef, Western Australia. Pachyseris speciosa hosted mainly thesame Symbiodinium C type similar to C3 irrespective of sampling depth. By contrast, Seriatopora hystrixhosted predominantly Symbiodinium type D1a or D1a-like at shallow depths while those in deeperwater 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 April2009) for P. speciosa and in November 2008 only for S. hystrix, suggesting a reduction in metabolicenergy expended for every unit of energy obtained from photosynthesis. However, in April 2009, shallowcolonies of S. hystrix exhibited decreased P/R ratios down to depths of approximately 23 m, below whichthe ratio increased towards the maximum depth sampled. This pattern was mirrored by changes in tissuebiomass determined as total protein content. The depth of change in the direction of the P/R ratio correlatedwith a shift from Symbiodinium D to C-dominated colonies. We conclude that while photobiologicalflexibility is vital for persistence in contrasting light regimes, a shift in Symbiodinium type may also confer afunctional advantage albeit at a metabolic cost with increased depth.

AB - The photobiology of two reef corals and the distribution of associated symbiont types were investigatedover a depth gradient of 0–60 m at Scott Reef, Western Australia. Pachyseris speciosa hosted mainly thesame Symbiodinium C type similar to C3 irrespective of sampling depth. By contrast, Seriatopora hystrixhosted predominantly Symbiodinium type D1a or D1a-like at shallow depths while those in deeperwater 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 April2009) for P. speciosa and in November 2008 only for S. hystrix, suggesting a reduction in metabolicenergy expended for every unit of energy obtained from photosynthesis. However, in April 2009, shallowcolonies of S. hystrix exhibited decreased P/R ratios down to depths of approximately 23 m, below whichthe ratio increased towards the maximum depth sampled. This pattern was mirrored by changes in tissuebiomass determined as total protein content. The depth of change in the direction of the P/R ratio correlatedwith a shift from Symbiodinium D to C-dominated colonies. We conclude that while photobiologicalflexibility is vital for persistence in contrasting light regimes, a shift in Symbiodinium type may also confer afunctional advantage albeit at a metabolic cost with increased depth.

U2 - 10.1098/rspb.2010.2321

DO - 10.1098/rspb.2010.2321

M3 - Journal article

C2 - 21106586

VL - 278

SP - 1840

EP - 1850

JO - Proceedings of the Royal Society B: Biological Sciences

JF - Proceedings of the Royal Society B: Biological Sciences

SN - 0962-8452

IS - 1713

ER -