The in situ light microenvironment of corals
Larkum, Anthony W. D.
Ralph, Peter J.
Nielsen, Daniel A.
Date of Issue2014
School of Biological Sciences
Singapore Centre for Environmental Life Sciences and Engineering
We used a novel diver-operated microsensor system to collect in situ spectrally resolved light fields on corals with a micrometer spatial resolution. The light microenvironment differed between polyp and coenosarc tissues with scalar irradiance (400–700 nm) over polyp tissue, attenuating between 5.1- and 7.8-fold from top to base of small hemispherical coral colonies, whereas attenuation was at most 1.5-fold for coenosarc tissue. Fluctuations in ambient solar irradiance induced changes in light and oxygen microenvironments, which were more pronounced and faster in coenosarc compared with polyp tissue. Backscattered light from the surrounding benthos contributed > 20% of total scalar irradiance at the coral tissue surface and enhanced symbiont photosynthesis and the local O2 concentration, indicating an important role of benthos optics for coral ecophysiology. Light fields on corals are species and tissue specific and exhibit pronounced variation on scales from micrometers to decimeters. Consequently, the distribution, genetic diversity, and physiology of coral symbionts must be coupled with the measurements of their actual light microenvironment to achieve a more comprehensive understanding of coral ecophysiology.
Limnology and oceanography
© 2014 the Association for the Sciences of Limnology and Oceanography, Inc. This paper was published in Limnology and Oceanography and is made available as an electronic reprint (preprint) with permission of E2014, by the Association for the Sciences of Limnology and Oceanography, Inc. The paper can be found at the following official DOI: [http://dx.doi.org/10.4319/lo.2014.59.3.0917]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.