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Article
Modulation of Light-Enhancement to Symbiotic Algae by Light-Scattering in Corals and Evolutionary Trends in Bleaching
PLoS ONE
  • Luisa A. Marcelino, Northwestern University; Chicago Field Museum of Natural History
  • Mark W. Westneat, Chicago Field Museum of Natural History
  • Valentina P. Stoyneva, Northwestern University
  • Jillian Henss, Northwestern University; Chicago Field Museum of Natural History
  • Jeremy Rogers, Northwestern University
  • Andrew J. Radosevich, Northwestern University
  • Vladimir Turzhitsky, Northwestern University
  • Margaret Siple, Northwestern University; Chicago Field Museum of Natural History
  • Andrew Fang, Northwestern University
  • Timothy D. Swain, Northwestern University; Chicago Field Museum of Natural History
  • Jennifer Fung, Northwestern University
  • Vadim Backman, Northwestern University
Document Type
Article
Publication Date
4-22-2013
Keywords
  • Corals,
  • Bleaching,
  • Light scattering,
  • Phylogenetic analysis,
  • Algae,
  • Phylogenetics,
  • Coral reefs,
  • Photons
Abstract

Calcium carbonate skeletons of scleractinian corals amplify light availability to their algal symbionts by diffuse scattering, optimizing photosynthetic energy acquisition. However, the mechanism of scattering and its role in coral evolution and dissolution of algal symbioses during “bleaching” events are largely unknown. Here we show that differences in skeletal fractal architecture at nano/micro-lengthscales within 96 coral taxa result in an 8-fold variation in light-scattering and considerably alter the algal light environment. We identified a continuum of properties that fall between two extremes: (1) corals with low skeletal fractality that are efficient at transporting and redistributing light throughout the colony with low scatter but are at higher risk of bleaching and (2) corals with high skeletal fractality that are inefficient at transporting and redistributing light with high scatter and are at lower risk of bleaching. While levels of excess light derived from the coral skeleton is similar in both groups, the low-scatter corals have a higher rate of light-amplification increase when symbiont concentration is reduced during bleaching, thus creating a positive feedback-loop between symbiont concentration and light-amplification that exposes the remaining symbionts to increasingly higher light intensities. By placing our findings in an evolutionary framework, in conjunction with a novel empirical index of coral bleaching susceptibility, we find significant correlations between bleaching susceptibility and light-scattering despite rich homoplasy in both characters; suggesting that the cost of enhancing light-amplification to the algae is revealed in decreased resilience of the partnership to stress.

Comments

©2013 Marcelino et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Additional Comments
NSF grant #s: CBET 0937987, DEB-0844745
ORCID ID
0000-0002-6485-6823
ResearcherID
M-7702-2013
DOI
10.1371/journal.pone.0061492
Citation Information
Luisa A. Marcelino, Mark W. Westneat, Valentina P. Stoyneva, Jillian Henss, et al.. "Modulation of Light-Enhancement to Symbiotic Algae by Light-Scattering in Corals and Evolutionary Trends in Bleaching" PLoS ONE Vol. 8 Iss. 4 (2013) p. e61492 ISSN: 1932-6203
Available at: http://works.bepress.com/timothy-swain/14/