red spectrum helps to lighten up dark corals? Interesting study inside.

[SunnyX]

I was searching things in Google as I usually do when I stumbled upon this interesting article: http://www.springerlink.com/content/...0/fulltext.pdf

It is over 20 years old but has some interesting findings.


"The final values for the pigment and zooxanthellae densities
of Montipora verrucosa from each acclimation treatment
are given in Table 1. Chlorophyll a per unit surfacearea
differed significantly among treatments (p < 0.0001).
Red-grown corals had significantly less chlorophyll a per
unit surface area than corals from the other treatments
(p < 0.05, Duncan's multiple-range test). Blue and lowintensity
white-grown corals had high levels of chlorophyll
a per unit area.
There were also significant differences among treatments
in terms of algal density (p = 0.0004). Corals grown
in red light had a significantly lower density of zooxanthellae
(p < 0.05, Duncan's multiple-range test), while
there were no differences among the other acclimation
treatments. It also appears that the amount of chlorophyll
a per algal cell was the same for all acclimation treatments
(p > 0.5).
Some coral fragments that remained unused at the end
of the experiment, had been in the red-light treatment for
more than 60 d. They were almost entirely free of algae
and appeared white, but retained complete coverage of
living animal tissue. We have not been able to obtain this
degree of bleaching with any other method, including
prolonged shading"

[SunnyX]

Another quote from the study:

"In a recent paper (Kinzie etal., 1984), it was shown
that the coral/algal symbiotic system, as well the zooxanthellae
in vitro responded differently under long-term
culture in light of differing spectral composition. In particular,
corals grown under blue or white light showed
increased growth and had higher algal densities than
corals grown in green or red light. It was suggested that
the blue-light response represented a physiological adaptation
to provide higher photosynthetic efficiency with increasing
depth in the field. These results suggested that a
measure of the photosynthetic ability of color-adapted
corals would give a direct test of the CCA model. Two
hypotheses were formulated that could be tested using this
coral/algal system. The first, a statement directed at CCA,
is that corals grown in a particular acclimation color
would have higher photosynthetic capacity or efficiency
when tested in light of that color than in light of other
colors. This differs from Engelmann's theory in that it is a
statement of adaptation in the physiological rather than
the evolutionary time frame. The second hypothesis, a
statement about the mechanism of CCA, follows from a
suggestion made by Kinzie etal. (1984), which was that
corals grown in blue light might show responses characteristic
of deep-living or low-light species, while corals
grown in red light would respond as if they were grown in
shallow-water, high-light environments. The idea that light
quality rather than light intensity may regulate the photic
response of the coral/algal association depends on the fact
that in shallow water the ratio of long-wavelength to shortwavelength
light is higher than in deep water (Dustan,
1982). "

[RicksReefs]

yes, it's been known for a while now that bad lighting bleaches coral.