Acclimatization of symbiotic corals to mesophotic light environments through wavelength transformation by fluorescent protein pigments

Edward G. Smith, Cecilia D’Angelo, Yoni Sharon, Dan Tchernov, Joerg Wiedenmann

Research output: Contribution to journalArticleResearchpeer-review

29 Citations (Scopus)

Abstract

The depth distribution of reef-building corals exposes their photosynthetic symbionts of the genus Symbiodinium to extreme gradients in the intensity and spectral quality of the ambient light environment. Characterizing the mechanisms used by the coral holobiont to respond to the low intensity and reduced spectral composition of the light environment in deeper reefs (greater than 20 m) is fundamental to our understanding of the functioning and structure of reefs across depth gradients. Here, we demonstrate that host pigments, specifically photoconvertible red fluorescent proteins (pcRFPs), can promote coral adaptation/acclimatization to deeper-water light environments by transforming the prevalent blue light into orange-red light, which can penetrate deeper within zooxanthellae-containing tissues; this facilitates a more homogeneous distribution of photons across symbiont communities. The ecological importance of pcRFPs in deeper reefs is supported by the increasing proportion of red fluorescent corals with depth (measured down to 45 m) and increased survival of colour morphs with strong expression of pcRFPs in long-term light manipulation experiments. In addition to screening by host pigments from high light intensities in shallow water, the spectral transformation observed in deeper-water corals highlights the importance of GFP-like protein expression as an ecological mechanism to support the functioning of the coral –Symbiodinium association across steep environmental gradients.

Original languageEnglish
Article number20170320
Number of pages9
JournalProceedings of the Royal Society B: Biological Sciences
Volume284
Issue number1858
DOIs
Publication statusPublished - 12 Jul 2017

Keywords

  • Chromatic adaptation
  • Corals
  • Green fluorescent proteins
  • Light
  • Mesophotic reefs
  • Symbioses

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