Light gradients and optical microniches in coral tissues

Wangpraseurt, D; Larkum, AWD; Ralph, PJ; Kühl, M

Light gradients and optical microniches in coral tissues

Wangpraseurt, D

Larkum, AWD

Ralph, PJ

Kühl, M

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Publication Type:: Journal Article
Citation:: Frontiers in Microbiology, 2012, 3 (AUG)
Issue Date:: 2012-01-01

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Field	Value	Language
dc.contributor.author	Wangpraseurt, D https://orcid.org/0000-0003-4834-8981	en_US
dc.contributor.author	Larkum, AWD https://orcid.org/0000-0002-0420-134X	en_US
dc.contributor.author	Ralph, PJ https://orcid.org/0000-0002-3103-7346	en_US
dc.contributor.author	Kühl, M https://orcid.org/0000-0002-1792-4790	en_US
dc.date.available	2012-08-13	en_US
dc.date.issued	2012-01-01	en_US
dc.identifier.citation	Frontiers in Microbiology, 2012, 3 (AUG)	en_US
dc.identifier.uri	http://hdl.handle.net/10453/22157
dc.identifier.uri	http://hdl.handle.net/10453/35883
dc.description.abstract	Light quantity and quality are among the most important factors determining the physiology and stress response of zooxanthellate corals. Yet, almost nothing is known about the light field that Symbiodinium experiences withintheircoralhost, andthebasic opticalproperties of coral tissue are unknown.We used scalar irradiance microprobes to characterize vertical and lateral light gradients within and across tissues of several coral species. Our results revealed the presence of steep light gradients with photosynthetically available radiation decreasing by about one order of magnitude from the tissue surface to the coral skeleton. Surface scalar irradiance was consistently higher over polyp tissue than over coenosarc tissue in faviid corals. Coral bleaching increased surface scalar irradiance by ~150% (between 500 and 700 nm) relative to a healthy coral. Photosynthesis peaked around 300 μm within the tissue, which corresponded to a zone exhibiting strongest depletion of scalar irradiance. Deeper coral tissue layers, e.g., ~1000 μm into aboral polyp tissues, harbor optical microniches, where only ~10% of the incident irradiance remains. We conclude that the optical microenvironment of corals exhibits strong lateral and vertical gradients of scalar irradiance, which are affected by both tissue and skeleton optical properties. Our results imply that zooxanthellae populations inhabit a strongly heterogeneous light environment and highlight the presence of different optical microniches in corals; an important finding for understanding the photobiology, stress response, as well as the phenotypic and genotypic plasticity of coral symbionts. © 2012 Wangpraseurt, Larkum, Ralph and Kühl.	en_US
dc.relation.ispartof	Frontiers in Microbiology	en_US
dc.relation.isbasedon	10.3389/fmicb.2012.00316	en_US
dc.title	Light gradients and optical microniches in coral tissues	en_US
dc.type	Journal Article
utslib.citation.volume	AUG	en_US
utslib.citation.volume	3	en_US
utslib.for	0605 Microbiology	en_US
utslib.for	0502 Environmental Science and Management	en_US
utslib.for	0503 Soil Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	closed_access
pubs.issue	AUG	en_US
pubs.publication-status	Published	en_US
pubs.volume	3	en_US

Abstract:

Light quantity and quality are among the most important factors determining the physiology and stress response of zooxanthellate corals. Yet, almost nothing is known about the light field that Symbiodinium experiences withintheircoralhost, andthebasic opticalproperties of coral tissue are unknown.We used scalar irradiance microprobes to characterize vertical and lateral light gradients within and across tissues of several coral species. Our results revealed the presence of steep light gradients with photosynthetically available radiation decreasing by about one order of magnitude from the tissue surface to the coral skeleton. Surface scalar irradiance was consistently higher over polyp tissue than over coenosarc tissue in faviid corals. Coral bleaching increased surface scalar irradiance by ~150% (between 500 and 700 nm) relative to a healthy coral. Photosynthesis peaked around 300 μm within the tissue, which corresponded to a zone exhibiting strongest depletion of scalar irradiance. Deeper coral tissue layers, e.g., ~1000 μm into aboral polyp tissues, harbor optical microniches, where only ~10% of the incident irradiance remains. We conclude that the optical microenvironment of corals exhibits strong lateral and vertical gradients of scalar irradiance, which are affected by both tissue and skeleton optical properties. Our results imply that zooxanthellae populations inhabit a strongly heterogeneous light environment and highlight the presence of different optical microniches in corals; an important finding for understanding the photobiology, stress response, as well as the phenotypic and genotypic plasticity of coral symbionts. © 2012 Wangpraseurt, Larkum, Ralph and Kühl.

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http://hdl.handle.net/10453/22157