Split lighting schedule for more growth?

[Big E]

In Moya et al., 2006 above they got the highest daily calcification after the longest photoperiod they tried (20 hrs), but they only did this for a couple of days. I wouldn't want to rule out the possibility that a very long photoperiod could screw up some other aspect of the coral's biology over time.

This was the point I was trying to make but maybe explained it poorly early on in this thread. Focusing just on the intensity of the light & it's relationship to calcification isn't the whole story.

Some comments here on effects of UV rays & instensity.
http://www.advancedaquarist.com/2007/4/aafeature/view?searchterm=None

"A recent and very interesting paper (Banaszak et al., 2006) discusses the likelihood that many (if not all) zooxanthellae clades can produce natural sunscreens to protect themselves and their hosts from ultraviolet radiation. These researchers now believe that major clade groups (A, B, C, D and E) can produce these colorless, protective substances called mycosporine-like amino acids (MAAs). This contradicts previous beliefs based on research conducted with symbionts isolated from hosts and then cultured under relatively low light intensity (~70 µmole photons·m²·sec). It now seems that higher light intensities and/or ultraviolet radiation are needed in order for the zooxanthellae to make these pigments (the coral host can not, since shikimate pathway is known to occur only in plants and bacteria.

However, MAAs can be obtained through diet by corals).
Does this change the opinion that aquarium lamps, especially metal halides and mercury vapors, should be shielded with a UV-absorbing lens? No â€"œ the results of Banaszak’s research only reinforces the notion that we should shield our aquarium inhabitants from potentially harmful UV radiation. For instance, a coral, grown in a dimly lighted portion of an aquarium, could be exposed to relatively intense UV radiation if it is moved only a few inches into a ‘brighter’ spot. These researchers also note the production of MAAs is an energetically expensive process (they quote a figure that 19% of a cell’s total energy budget is required for production of the MAA Palythine â€"œ energy that otherwise could be used for growth and reproduction).

In addition, it is now believed that all symbiotic zooxanthellae have, to varying degrees, the ability to produce xanthophylls. Xanthophylls (diadinoxanthin and diatoxanthin) act as photoprotectants, absorbing visible light (mostly in the violet/blue portion of the spectrum) and ‘dumping’ this energy as non-radiant heat. In effect, the conversion of these two xanthophylls under conditions of high light intensities act as a ‘safety’ valve and channel light energy away from the photosynthetic apparatus in zooxanthellae."

There is also a study done by Riddle on how the light from halides can overheat corals. I can't seem to find the article at the moment.

 

[Meisen]

[i


Hope this helps [/B]

Thanks it does, I will digest all that and post some clarification to my Qs.

 

[reef / aholic]

Photosynthesis on coral varies throughout the day.
www.science.uts.edu.au/des/StaffPages/PeterRalph/photosynthesis.html

Photosynthesis and Photoadaptation
http://www.personal.psu.edu/sbj4/aquarium/articles/Photosynthesis.htm

 

[reefclown]

With good reflectors and when everything is kept meticulously clean, lower wattage metal halides (150 - 250 watts) or T5 assemblages can provide all the light you could need or want. Going with anything but the best quality reflector, and allowing even a tiny bit of salt spray to accumulate is effectively flushing money down the drain.

MCsaxmaster, Awesome advice, simple yet effective, but how many do you think follow this simple principle? Is it unfortunately often a case of aesthetics over function ?

Is there anything more optimal in the U.S. than our current UK spec of Lumenarc III for single ended halides and gull wing for t5 lamps?

What are your thoughts on running lamps on a moving light rail, kinda like simulating light cloud cover moving in and out fairly rapidly, but allowing a single light source to cover a greater area whilst also reducing the effect of shadow? Currently using the US produced lightrail system

reef/aholic, firstly thanks for the links, unfortunately it's too much of a strain for some us with fried brains

Any chance you could lay down in simpler terms what the links imply, so the unitiated can get a grip on what to look for

I'm a firm believer that one should not give 'handouts' to the knowledge hungry, it serves no purpose, but a slightly higher level perspective on your thoughts would be really appreciated and really helpfull