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Marine Ecology Progress Series

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MEPS 420:91-101 (2010)  -  DOI:

Acquisition and assimilation of carbon in non-bleached and bleached corals

A. D. Hughes1,2,3,*, A. G. Grottoli1, T. K. Pease2, Y. Matsui1

1School of Earth Sciences, The Ohio State University, Columbus, Ohio 43210, USA
2University of Texas Marine Science Institute, Port Aransas, Texas 78373, USA
3Scottish Association for Marine Science, Oban PA37 1QA, UK

ABSTRACT: Reef-forming corals cycle carbon (C) between the coral host, their endosymbiotic algae, and their skeleton. At elevated sea-surface temperatures this relationship breaks down and the corals bleach by expelling their endosymbiotic algae or these algae lose their photosynthetic pigments. The effect of thermally induced bleaching on the C cycling of 2 ecologically important coral species was investigated. The acquisition and assimilation of photoautotrophically and heterotrophically acquired C was examined via pulse-chase labeling experiments in thermally bleached and non-bleached Montipora capitata and Porites compressa corals. In non-bleached corals photoautotrophic and heterotrophic C were acquired and assimilated very differently. Namely, photoautotrophically acquired C was used to meet short-term metabolic demands and calcification, whereas heterotrophically acquired C was retained in both the coral host and endosymbiotic algae. In bleached corals there was a dramatic reduction in the assimilation of photoautotrophically acquired C by the endosymbiotic algae, in the translocation of C from the algae to the coral host, and in the C assimilated in the skeleton. The level of heterotrophically acquired C assimilated into bleached corals was similar to that in non-bleached corals, and was a direct source of organic C to the endosymbiotic algae. This host-to-endosymbiotic algal supply of heterotrophic C may stimulate endosymbiotic algal recovery. These findings show the importance of both photoautotrophic and heterotrophic C to coral function and demonstrate that both play a crucial role in the recovery from bleaching.

KEY WORDS: Porites compressa · Montipora capitata · Coral bleaching · Resilience · Stable isotope · Heterotrophy · Photoautotrophy

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Cite this article as: Hughes AD, Grottoli AG, Pease TK, Matsui Y (2010) Acquisition and assimilation of carbon in non-bleached and bleached corals. Mar Ecol Prog Ser 420:91-101.

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