Dana's Talk - Red, Blue and UV Light

[sfsuphysics]

Unless Mark's picture is a log scale, there's significantly more red absorption in chlorophyll a.

Are you looking at the chlorophyll F curve? If so, ignore that. I think that is only in certain fairly rare cyanobacteria.
The area under the A curve is larger in the blue.

Nope I mean ChloA, it's the dark green bump, and yeah it's larger under the blue, but still pretty significant in size unlike the ChlorC absorption regions (my picture) which have almost no red absorption.

 

[DanaRiddle]

Here's a link to UV photoinhibition:
http://www.advancedaquarist.com/2004/8/aafeature

Violet, blue, green, and red light can definitely cause photoinhibition if intensity is high. Xanthophylls can absorb light (roughly 400-475nm) and shunt it away from the photosynthetic apparatus. Two xanthophylls in particular play an important part and protect zooxanthellae: Diatoxanthin and Diadinoxanthin. Note these pigments do not absorb red. Too much red light will cause reduction in photopigment content or zooxanthellae population. Just how much red light causes this is the matter of debate.

I'm back in Hawaii and will soon start experiments with light and its effects on zooxanthellae chlorophyll content. We know for sure too much red light is destructive. What we do not know is how fixtures with added red light (such as Radion LED luminaires) affects corals and their symbiotic algae.

Re: Fluorescence. Any of the violet/blue LEDs produce enough excitation to showcase fluorescence, but this effect is washed out by other portions of the spectrum.

For those so interested:

Kinzie, R.A. and T. Hunter, 1987. Effect of light quality on photosynthesis of the reef coral Montipora verrucosa. Mar. Biol., 94:95-109.

Kinzie, R.A., 1993. Effects of ambient levels of solar ultraviolet radiation on zooxanthellae and photosynthesis of the reef coral Montipora verrucosa. Mar. Biol., 116:319-327.

Kinzie, R.A., P.L. Jokiel and R. York, 1984. Effects of light of altered spectral composition on coral zooxanthellae associations and on zooxanthellae in vitro. Mar. Biol., 78:239-248.

Kinzie, R.A. and T. Hunter, 1987. Effect of light quality on photosynthesis of the reef coral Montipora verrucosa. Mar. Biol., 94: 95-109.

Dana

 

[Gomer]

If you have the tools at your disposal (or maybe this is already know), it would be interesting to figure out how much of photoinhibition is integrated intensity vs spectral density.

Translation: 1 watt of broad band 455 nm center blue LED light vs 1 watt of narrow band 455 nm laser light (spatial density match, of course).

This has relevance to the emission profile of fluorescent lights vs led lights.