The Importance Of Light Spectrum

[jaypeecee]

Hi Everyone,

If you were ever in any doubt about the importance of light spectrum, please take a look at the following:

Blue light reduces photosynthetic efficiency of cyanobacteria through an imbalance between photosystems I and II - Photosynthesis Research

Several studies have described that cyanobacteria use blue light less efficiently for photosynthesis than most eukaryotic phototrophs, but comprehensive studies of this phenomenon are lacking. Here, we study the effect of blue (450 nm), orange (625 nm), and red (660 nm) light on growth of the...

link.springer.com

Although the document title gives the impression that blue light and cyanobacteria are being spotlighted (pun intended), there is a wealth of information in this paper. In particular:

"Engelmann continued his studies with cyanobacteria from the genus Oscillatoria, demonstrating that in these cyanobacteria, not only red and blue light but also orange light resulted in high O2 production rates (Engelmann 1883, 1884). Engelmann’s findings were criticized for many years, but 60 years later, his results were confirmed by Emerson and Lewis, who showed that the phycobiliproteins of cyanobacteria and red algae play a key role in light-harvesting for photosynthesis".

I have often been concerned that light at some wavelengths may promote algae and/or cyanobacteria - orange light at 625 nm in particular. Many aquarium lighting products have substantial output at this wavelength. I prefer to see products with output at 660 nm corresponding to the peak response of chlorophyll b. And at the blue end of the spectrum, 450nm for chlorophyll a. Oh, yes, and a good helping of green!

JPC

 

[Paulthewitt]

Are you able to put a summary in peasant Anglian for those of us who cannot understand it please? 😂

I’m particularly interested in the blue light as I have covered mine up as the cooler light looks weird and I heard algae thrives more on it?

 

[jaypeecee]

Hi Folks,

I prefer to see products with output at 660 nm corresponding to the peak response of chlorophyll b. And at the blue end of the spectrum, 450nm for chlorophyll a.

I need to check the accuracy of my two sentences above. But that will have to wait until tomorrow. This in no way changes the importance of the cited paper.

JPC

 

[jaypeecee]

Hi @Paulthewitt

I’m particularly interested in the blue light as I have covered mine up as the cooler light looks weird and I heard algae thrives more on it?

It's possibly not such a good idea to cover the blue light. Both ends of the photosynthetic spectrum - blue and red - are particularly important to plants. Are you using fluorescent tubes or LEDs? If the latter, is your lighting dimmable?

JPC

 

[oreo57]

I see nothing applicable to eukaryotes i.e normal algea and plants.
To point to one difference:

Effects of light of altered spectral composition on coral zooxanthellae associations and on zooxanthellae in vitro - Marine Biology

Pocillopora damicornis (Linnaeus) and Montipora verrucosa (Lamarck) were collected from Hawaiian reefs. In two experiments (September 1979-January 1980: ca. 4 mo; August-October 1980; ca. 2 mo), these reef corals were grown under sunlight passed through filters producing light fields of similar...

link.springer.com

The in vitro cultures of zooxanthellae from M. verrucosa exhibited growth rates in light of altered spectral quality that correlated with the responses of the host coral species: blue and white light supported significantly greater growth than green light, and red light resulted in the lowest growth rate.

 

[alto]

I see nothing applicable to eukaryotes i.e normal algea and plants.

all the references to Chl a


I thought the point of the post and interest of the paper was in regards Cyanobacteria which are present in many aquariums
(I don’t know of too many freshwater Aquariums with zooxanthellae)

 

[oreo57]

all the references to Chl a


I thought the point of the post and interest of the paper was in regards Cyanobacteria which are present in many aquariums
(I don’t know of too many freshwater Aquariums with zooxanthellae)

Blue green algae is effectively cured/contained w/ antibiotics.
Personally in over 4 years cyano has been the very least of my worries..
Even results between prokaryotic species is err "complicated".

The specific growth rate of C. sorokiniana did not change with the percentage red light. In contrast, the specific growth rate of Synechocystis strongly increased with the percentage red light, up to 65% red light, and then gradually saturated

Point was it's risky assuming effects from one species to another much less from one phylum to another.
zooxanthella use chl a and c but are more closely related to normal algae than any procaryote.

Although the document title gives the impression that blue light and cyanobacteria are being spotlighted (pun intended), there is a wealth of information in this paper.

Seems you were implying "spreading out" your conclusions. If not, my mistake.

now as to spectrum being important a consideration of the Emerson effect on photosynthetic higher organisms would be interesting.
The whole PSI/II thing is complicated.
Not to mention the issues of results using monochrome lighting in small numbers unlike most aquariums whose spectrum (even w/ RGB) is much wider.

How It Works

Lear about the emerson effect and how its effects on photosynthesis can reduce growing times and increase crop yields through light manipulation alone

aigrowlight.com

Bottom line for me personally is chasing tweaks of spectrum for algae control seems to be a very difficult endeavor if not completely fruitless.
I am open to be proven wrong but never saw anything that was helpful or easy to implement.
The whole PSI/II thing is complicated as is saturation point effects.
Better to maintain a healthy well balanced environment than worry about tweaking the spectrum.

Heck one can adj. growth rates using temp too

Thanks for the paper, I like to post them myself on occasion.

In case you are wondering and to sum it up a bit. I don't think you're wrong per se but see little usable utility in it.

Pick your spectrum. BTW supports your hypothesis but can you actually see a practical use for it?

Colorful niches of phototrophic microorganisms shaped by vibrations of the water molecule

The photosynthetic pigments of phototrophic microorganisms cover different regions of the solar light spectrum. Utilization of the light spectrum can be interpreted in terms of classical niche theory, as the light spectrum offers opportunities for niche differentiation and allows coexistence of...

www.nature.com

They developed a competition model that predicts that red picocyanobacteria should become dominant in green light, green picocyanobacteria should become dominant in red light, whereas red and green picocyanobacteria can coexist in the full spectrum provided by white light. The results of their competition experiments were consistent with these predictions. These studies demonstrated that light color plays a decisive role in the species composition of phototrophic communities, at least in controlled laboratory experiments.

 

[dw1305]

Hi all.

Blue green algae is effectively cured/contained w/ antibiotics.

We don't have access to antibiotics in most of Europe, which I see as a <"plus point for human health">, even if it restricts what we can put in our aquariums.

Bottom line for me personally is chasing tweaks of spectrum for algae control seems to be a very difficult endeavor if not completely fruitless.

That would be my thought as well. It is back to the same sun over the last 4.5 billion years and <"the likelihood that all photosynthetic organisms have a common ancestor">.

You can ignore the non-photosynthetic bacteria, so "d" & "e" are what we are interested in and I'd say "what is sauce for the goose is sauce for the gander".

cheers Darrel

 

[jaypeecee]

I thought the point of the post and interest of the paper was in regards Cyanobacteria which are present in many aquariums

Hi @alto

Yes, my apologies. I wasn't at all clear what prompted me to start the thread, was I? I should have gone to bed and left it until this morning! In previous UKAPS discussions about aquarium lighting, the emphasis (understandably) has been on providing the 'right' spectrum for the plants themselves and viewing aesthetics. But, I have long been concerned about the impact of lighting on algae and cyanobacteria. This paper addresses both of these. It is heavy-going but it's worth persevering with it - in my opinion.

JPC

 

[jaypeecee]

Seems you were implying "spreading out" your conclusions. If not, my mistake.

Hi @oreo57

Sorry, you've lost me there.

Personally in over 4 years cyano has been the very least of my worries..

That may be your experience but take a look at the sheer number of people on UKAPS that have problems with cyano - myself included. BTW, I am very much aware of other factors that contribute to the blue-green menace and algae - particularly dissolved organic matter (C and P).

Bottom line for me personally is chasing tweaks of spectrum for algae control seems to be a very difficult endeavor if not completely fruitless.

If aquarium lighting incorporates LEDs matched to the absorption/action spectrum of plants, then one has a good starting point. Some manufacturers provide just this. Then, it's a simple matter of adjusting the intensity of these LEDs accordingly. It's not rocket science. This is PAR (!) for the course with hydroponics, horticulture and agriculture.

That's enough for now.

JPC

 

[dw1305]

Hi all,

But, I have long been concerned about the impact of lighting on algae and cyanobacteria. This paper addresses both of these. It is heavy-going but it's worth persevering with it

What about light intensity? (From <"Blue light reduces photosynthetic efficiency of cyanobacteria through an imbalance between photosystems I and II">) You would need a PAR meter and also to have enough light for your plants and too little for your BGA.

I'm going to assume this the bit (in <"Colorful niches of phototrophic microorganisms shaped by vibrations of the water molecule">) that has interested you as well?

......... Peaks in the underwater light spectrum at wavelengths below the sixth harmonics (<514 nm) are captured by chlorophyll a and b, divinyl-chlorophylls a and b and accessory carotenoids. The peak in the underwater light spectrum between the sixth and fifth harmonics (514–604 nm) is captured by the phycoerythrins of red algae and cyanobacteria. Peaks in the underwater light spectrum between the fifth and fourth harmonics (604–760 nm) are captured by phycocyanin, chlorophylls a, b and d..........

I still think that there is too much of an overlap in the spectra of "d" (BGA) & "e" (Red Algae, Green Algae, Higher Plants, Diatoms and Chrysophytes).

This graph (from "Blue light reduces........") shows what I mean.

Light absorption spectra of the cyanobacterium Synechocystis sp. PCC 6803 (black line) and the green alga C. sorokiniana 211-8K (grey line) acclimated to 35 µmol photons m−2 s−1 white light.

If aquarium lighting incorporates LEDs matched to the absorption/action spectrum of plants, then one has a good starting point. Some manufacturers provide just this. Then, it's a simple matter of adjusting the intensity of these LEDs accordingly.

There is a practical solution if you want to experiment, you can get Blue/Red LED arrays for Hydroponics. They give you more "bang for your buck", but have a very low CRI and you may not be able to find spectra for them.

cheers Darrel

 

[jaypeecee]

Hi @dw1305

What about light intensity?

I didn't mention this because I (wrongly?) assumed that it would obviously have a positive correlation with algae growth.

I still think that there is too much of an overlap in the spectra of "d" (BGA) & "e" (Red Algae, Green Algae, Higher Plants, Diatoms and Chrysophytes).

I'm not sure about that. It is easy to select LED devices with centre wavelengths that differ by only a few nanometres (nm).

There is a practical solution if you want to experiment, you can get Blue/Red LED arrays for Hydroponics. They give you more "bang for your buck", but have a very low CRI and you may not be able to find spectra for them.

I generally buy LEDs from the likes of RS Components who also provide manufacturers' published data.

JPC

 

[Paulthewitt]

Hi @Paulthewitt



It's possibly not such a good idea to cover the blue light. Both ends of the photosynthetic spectrum - blue and red - are particularly important to plants. Are you using fluorescent tubes or LEDs? If the latter, is your lighting dimmable?

JPC

Thanks - I will uncover. It’s led with electric tape over the blue leds.

Couple of other useful and simplified replies here were helpful too - thanks all

 

[ceg4048]

Bottom line for me personally is chasing tweaks of spectrum for algae control seems to be a very difficult endeavor if not completely fruitless.
I am open to be proven wrong but never saw anything that was helpful or easy to implement.
The whole PSI/II thing is complicated as is saturation point effects.
Better to maintain a healthy well balanced environment than worry about tweaking the spectrum.

Thank you. This has been our position for over a decade. In our particular tank environment BGA is neither triggered by the availability of orange/red light and will not be suppressed by the substitution of monochrome blue light. Clearly, the study did not demonstrate that the growth rate using blue light was zero, only that it was less than that of orange/red. Good tank husbandry, minimizing excessive PAR intensity, frequent and large water changes, clean filters and careful attention to CO2/nutrients (especially NO3) is the wisest course. Blue light will never save you from poor attention to the more important details of tank husbandry.

Cheers,

 

[alto]

In our particular tank environment

Sure I’m not the only one Curious what tanks you’re running these days?

 

[ceg4048]

Sure I’m not the only one Curious what tanks you’re running these days?

Hi alto,
I drained my tank while I was very ill for quite a while, and no way I could do my water changes (and you know how fanatical I am about that) but it's the same 200 gallon that I just let run wild as a dry start - or maybe a dry end? It's just sitting there with the programmable lights running - 2 years - a real bummer mate.

Cheers,

 

[alto]

Sorry to hear that
hope you’re doing better ... now imagining a 2 year old 200 gallon dry start jungle

 

[jaypeecee]

In our particular tank environment BGA is neither triggered by the availability of orange/red light and will not be suppressed by the substitution of monochrome blue light.

Hi @ceg4048

You may be correct but what (scientific) evidence do you have to back up your statement? I'd also like to pick up on your word 'triggered'. I don't see it as necessarily 'triggered'. Isn't it a case of orange light at 625nm having the potential to 'feed' cyanobacteria with light of the very wavelength that it is well-equipped to utilize? Red light at around 660nm is needed by plants as it corresponds to one of the absorption/action peaks of chlorophyll a - as I'm sure you are very much aware. So, red light is here to stay. The other chlorophyll a peak is at 430nm give or take a gnat's whisker. This is at the blue end of the spectrum and, according to Dr Bruce Bugbee*, is very much needed but, in his words, 'shrinks plants'.

I know from previous posts that discussions about lighting can get somewhat 'heated'. Let's try to prevent this.

* Apogee Instruments

JPC

 

[dw1305]

Hi all,

This graph (from "Blue light reduces........") shows what I mean.

Light absorption spectra of the cyanobacterium Synechocystis sp. PCC 6803 (black line) and the green alga C. sorokiniana 211-8K (grey line) acclimated to 35 µmol photons m−2 s−1 white light.

I still can't see where there is enough difference between the two light absorption curves? The green algae are photosynthetically identical to higher plants (the form a clade <"the "Viridiplantae")>, so that would be the same for higher plant, fern or moss.

cheers Darrel

 

[jaypeecee]

Better to maintain a healthy well balanced environment than worry about tweaking the spectrum.

Hi @oreo57

I'm not questioning for one moment the need to maintain a healthy aquarium environment - that is a given. But that alone, in my experience, will not necessarily prevent problems with cyano outbreaks. Tweaking the spectrum on its own will not keep cyano at bay.

JPC