title: Heat generation and light scattering of green fluorescent protein-like pigments in coral tissue.
abstract: Green fluorescent protein (GFP)-like pigments have been proposed to have beneficial effects on coral photobiology. Here, we investigated the relationships between green fluorescence, coral heating and tissue optics for the massive coral Dipsastraea sp. (previously Favia sp.). We used microsensors to measure tissue scalar irradiance and temperature along with hyperspectral imaging and combined imaging of variable chlorophyll fluorescence and green fluorescence. Green fluorescence correlated positively with coral heating and scalar irradiance enhancement at the tissue surface. Coral tissue heating saturated for maximal levels of green fluorescence. The action spectrum of coral surface heating revealed that heating was highest under red (peaking at 680 nm) irradiance. Scalar irradiance enhancement in coral tissue was highest when illuminated with blue light, but up to 62% (for the case of highest green fluorescence) of this photon enhancement was due to green fluorescence emission. We suggest that GFP-like pigments scatter the incident radiation, which enhances light absorption and heating of the coral. However, heating saturates, because intense light scattering reduces the vertical penetration depth through the tissue eventually leading to reduced light absorption at high fluorescent pigment density. We conclude that fluorescent pigments can have a central role in modulating coral light absorption and heating.
authors.affiliation: Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark.
authors.forename: Niclas H
authors.initials: NH
authors.lastname: Lyndby
authors.affiliation: Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark.|Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, New South Wales 2007, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Kühl
authors.affiliation: Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark.|Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, New South Wales 2007, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wangpraseurt
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D000067493:Dynamic Light Scattering; D005453:Fluorescence; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006358:Hot Temperature; D010860:Pigments, Biological / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*
chemical_list: D010860:Pigments, Biological; D010940:Plant Proteins; D049452:Green Fluorescent Proteins