Breakdown of coral colonial form under reduced pH conditions is initiated in polyps and mediated through apoptosis

Hagit Kvitt, Esti Kramarsky-Winter, Keren Maor-Landaw, Keren Zandbank, Ariel Kushmaro, Hanna Rosenfeld, Maoz Fine, Dan Tchernov

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

Certain stony corals can alternate between a calcifying colonial form and noncalcifying solitary polyps, supporting the hypothesis that corals have survived through geologic timescale periods of unfavorable calcification conditions. However, the mechanisms enabling this biological plasticity are yet to be identified. Here we show that incubation of two coral species (Pocillopora damicornis and Oculina patagonica) under reduced pH conditions (pH 7.2) simulating past ocean acidification induce tissue-specific apoptosis that leads to the dissociation of polyps from coenosarcs. This in turn leads to the breakdown of the coenosarc and, as a consequence, to loss of coloniality. Our data show that apoptosis is initiated in the polyps and that once dissociation between polyp and coenosarc terminates, apoptosis subsides. After reexposure of the resulting solitary polyps to normal pH (pH 8.2), both coral species regenerated coenosarc tissues and resumed calcification. These results indicate that regulation of coloniality is under the control of the polyp, the basic modular unit of the colony. A mechanistic explanation for several key evolutionarily important phenomena that occurred throughout coral evolution is proposed, including mechanisms that permitted species to survive the third tier of mass extinctions.

Original languageEnglish
Pages (from-to)2082-2086
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume112
Issue number7
DOIs
StatePublished - 17 Feb 2015

Keywords

  • Apoptosis
  • Corals
  • Ocean acidification

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