I'd love to see some proper studies on the Emerson Effect and corals; it would be interesting to see which, if any, species it works for.About far red (700 - 760 nm) se this thread
https://www.reef2reef.com/threads/advanced-topic-thoughts-on-emerson-effect.369404/
Further on see this page
Search results for query: emerson effect
www.reef2reef.com
Sincerely Lasse
I'm not sure if there is any studies with zooxanthellae, but Dana told me it works basically the same way.
So, to be clear... A rise in o² is indicative of a increase in photosynthesis?
Exactly - and a rise in pH caused by consumed CO2 in the water. CO2 as an resource - C incorporated into the compounds that photosynthesis produce and O2 as a waste
It would be easy to test the photosynthetic effect of the light that way, but not necessarily the effectiveness of the light for corals - like I mentioned in the other thread (quoted below), sometimes corals grow faster under just blue light (as opposed to full-spectrum lighting) despite a drop in photosynthesis:
The study below tested Acropora variabilis and Porites lutea harvested from 2-6 m deep at maintained 6 m deep; they compared dark (no light), full-spectrum (the control), and blue light settings at 200 μmol and 400 μmol (they tested full-spectrum at 800 μmol as well, but 400 μmol was the highest they could get the blue); they used a metal halide light with polycarbonate filters to control what spectrum the corals were being exposed to - the corals grew (calcified) fastest under the blue light, but there was more photosynthesis under the full-spectrum (white) light:
"The light to dark calcification ratios of A. variabilis under 400 μmol photons m−2 s−1 of control and blue light were 8.4 and 10.5, respectively; while lower ratios were observed in P. lutea (3.4 and 4.5). In both cases, calcification under blue light exceeds even these of the control"
Frontiers | Light Enhanced Calcification in Hermatypic Corals: New Insights from Light Spectral Responses
Light enhanced calcification (LEC) is a well-documented phenomenon in reef-building corals. The main mechanism proposed for LEC is that photosynthetic CO2 up...www.frontiersin.org
So, under controlled PAR with metal halides, these shallow water corals grew faster under blue light than white, but but photosynthesis decreased drastically under blue light when compared to white.
To contrast with that, though, another study (using three different species of Acropora - A. tenuis, A. muricata, and A. intermedia at 100 μmol and 200 μmol [low numbers, I know] with LED's) compared different spectrums (the first link below) and found that the inclusion of some red light drastically increased the growth rate (the second link below; the green/yellow spectrum made a little bit of difference, but they didn't add much of it in with any of the three spectrums used; it may have made a bigger difference at higher intensities):
The actual study:
Another contrasting study - Stylophora pistillata from shallow (3 m) and deep (40 m) waters; the shallow specimens showed the highest photosynthesis rates under full-spectrum lighting, but the deepwater specimens showed the highest photosynthesis rates under blue lighting (sadly, they didn't measure growth rates, and the study only took place between March and April, so it was rather short, and results may have changed if the study had been longer).
The spectral quality of light is a key driver of photosynthesis and photoadaptation in Stylophora pistillata colonies from different depths in the Red Sea
SUMMARYDepth zonation on coral reefs is largely driven by the amount of downwelling, photosynthetically active radiation (PAR) that is absorbed by the symbiotic algae (zooxanthellae) of corals. The minimum light requirements of zooxanthellae are related to both the total intensity of downwelling...journals.biologists.com
So, does blue light grow Acropora or other SPS faster than full-spectrum (white) light? It depends on the coral (both species and individual specimen), the location and depth/temperature the coral is from, what light the corals are photo-acclimated to (a shallow water coral growing under blue light in a hobbyist tank for 5 years is likely going to be acclimated to blue light despite its origins), year-round weather conditions (storms and such play a big role in determining what light is reaching the water), the clade of zooxanthellae they're using, etc.
Does the kind of light used (metal halide vs t5 vs LED, etc.) make a difference, or is it all in the spectrum, intensity, and photoperiod? I don't think we'll be able to answer this unless someone is able to make LED's with the exact same spectrum as those other types of lighting, but I'd guess any differences would be minimal.
So, lots of different things go into the growth, and again, fast growth doesn't necessarily equate to excellent health/coloration (it might, but it also might not). Does each coral species have it's own optimal spectrum for growth/health/color? Probably, but I doubt it would perfectly match a different species own optimal spectrum, so I don't know that it would much matter in our tanks - instead, we'd need to find the optimal spectrum for a broad range of corals, which may not be optimal for any particular coral we keep:
"Zooxanthellate corals display contrasting photoacclimation responses, coral cover, colony morphologies and genetic richness along depth gradients33,49,50,51,52,53,54, which collectively suggest that coral species occupy different light niches."
Photosynthetic usable energy explains vertical patterns of biodiversity in zooxanthellate corals - Scientific Reports
The biodiversity in coral reef ecosystems is distributed heterogeneously across spatial and temporal scales, being commonly influenced by biogeographic factors, habitat area and disturbance frequency. A potential association between gradients of usable energy and biodiversity patterns has...www.nature.com
Personally, I'd expect to see similar (not the same, but similar) growth rates from a lot of corals under both blue and full-spectrum lights; some will likely do better under one than the other, but determining which is a lot of effort.
For that reason, like I've said before, at this point in time (barring a major, undeniable scientific breakthrough with our knowledge of corals and light), I would personally only suggest running the windex blue tanks if you really want to see the coral fluorescence pop (as mentioned by others, though, the colors may be best in the long run if you run different spectrums than just blue throughout the day). Like many others have mentioned in various forms by this point, I'd personally run a full-spectrum (white) light that leans somewhat more toward the blue side of things. Is that the "best" spectrum? Maybe, maybe not, but it seems like a good, safe place to start from.
The scientific explanation of degree Kelvin for light is if a black body will be heaten up to this temperature K - it will emit exact this colour for our eyes. It has not to do with which wavelengths that is involved.
Concept is 100%. I'd question the calcs on a few of those but no matter..The scientific explanation of degree Kelvin for light is if a black body will be heaten up to this temperature K - it will emit exact this colour for our eyes. It has not to do with which wavelengths that is involved.
The sun is 6500 K (about). The spectra looks like this
Degree K is our perception of light colour in which the same colour can be achieved with thousands of different combinations of wavelengths and their combined strengths
Sincerely Lasse
Exactly - and a rise in pH caused by consumed CO2 in the water. CO2 as an resource - C incorporated into the compounds that photosynthesis produce and O2 as a waste
Sincerely Lasse
Thanks for letting me know you like cats (in your avatar now). I think you had a dog there before? Maybe I'm wrong... I like dogs. To tell the truth... I love dogs!!! Don't like cats as much.
I was injured on the job 3 years ago. Now retired I was going to get and train a Mali but its not fair to the dog if I cant keep up.
I remember about your injury. Hope you are doing great and getting better each day! I'm sure you miss that dog!!! Keep it up!
There were(are) some t5's that may be close but are generally unpopular called lagoon or turquoise ect.
The 700nm peak is kind of " different".
Interesting - I know that some LED does that - Somewhere in my memory say that at least the early Kessils was constructed that way - but i do nor know where it is coming from.
I ordered some turquoise T5 bulbs from Germany. They are called Great Barrier Turquoise.Concept is 100%. I'd question the calcs on a few of those but no matter..
@Doctorgori yes k temps are sort of useless
Especially with metal halides that really take artistic license with their " ratings".
Anything over like 12000k is probably wildly inaccurate. Ushio looks to be one of the few exceptions
The Phoenix 14000k is more of a "20000k class" I.e. a blue bulb.
Anyways ..a legitimate k temp is only a part of the story as you can see.
A collection of spectrums from that solar black body and related k temps.
An led that truly would reproduce colors as you would see them underwater. Well at one spot, one time ect
Note that this particular led uses a violet not blue pump and RGB phosphors much like a t5.
But even if you could buy these here in the US I'd wager that few actually want things that " natural".
There were(are) some t5's that may be close but are generally unpopular called lagoon or turquoise ect.
The 700nm peak is kind of " different".
