Lighting and Cyanobacteria (BGA)

[jaypeecee]

Hi Everyone,

Some of you may have seen a thread I started a few weeks ago:

https://www.ukaps.org/forum/threads/cyanobacteria-identification-at-last.60496/

In the process of reading many articles and scientific papers on the subject of Cyanobacteria (aka Cyano), I looked into Cyano's need for light in order to reproduce and grow. I was already aware that Cyano contains chlorophyll a and what are known as accessory pigments, which work in tandem with chlorophyll a to feed these organisms. To cut a long story short, there is a blue-green pigment known as phycocyanin, which absorbs light at 620 nm give or take a gnat's whisker. This wavelength corresponds to the orange/red part of the spectrum. Now, a problem can arise here as some aquarium lighting manufacturers design and produce lighting that sometimes have a substantial light output at, or very near, this wavelength. There is at least one such manufacturer of which I'm aware that does just this according to their published spectra. The choice of LED* wavelengths and resulting overall spectrum is important in order to optimize plant growth but help to prevent/reduce growth of Cyano.

I would like to have the opportunity to discuss this very important topic in greater depth if anyone's 'up for it'. Please don't think this is some mad hairbrained idea that I'm harping on about. I think it's much too important to just brush aside. It would be good if someone here on UKAPS agrees with me. Otherwise, I'm going to feel very lonely. 🙁

*LED - I use this common abbreviation to mean 'light-emitting diode', i.e the semiconductor electronic device that itself, when suitably powered, produces light - be that visible or otherwise. If we're talking about that collection of LEDs in some enclosure above our tanks, I refer to that as a 'fixture'.

JPC 🙂

 

[X3NiTH]

620nm because ........

Lava



😎

 

[MirandaB]

I might get lost on some of the scientific stuff but I'd be very interested to hear what you have to say,Cyano is a problem which crops up often enough to warrant more investigation

 

[jaypeecee]

620nm because ........

Lava

View attachment 149821

😎

Hi @X3NiTH

Great to hear from you!

Would you care to elaborate on the above? Looks interesting.

JPC

 

[X3NiTH]

Photosynthesis likely evolved in darkness somewhere in a deep ocean abyss to take advantage of the energy surrounding Hydrothermal Sea Vents where the thermal energy of hot water emits light in the Far Infrared, this would be a dominant process. As a further evolutionary mechanism it would also have been advantageous to be able to derive energy from transient volcanic processes such as near vicinity release of Lava which would emit enormous amounts of radiant luminosity initially around 620nm which decreases as the lava cools and the Spectra lengthens until visible light is gone and your left with black body radiation in Far Infrared. Quite literally a Far Out’ idea!

The temptation to reduce or remove a spectra would most likely lead to ‘Chasing Cats’ specifically the one belonging to Schroedinger. Cyanobacteria are especially well adapted to make the best from what they’ve got leveraging Quantum Mechanics to do so.

Short answer!

🙂

 

[ceg4048]

there is a blue-green pigment known as phycocyanin, which absorbs light at 620 nm give or take a gnat's whisker. This wavelength corresponds to the orange/red part of the spectrum. Now, a problem can arise here as some aquarium lighting manufacturers design and produce lighting that sometimes have a substantial light output at, or very near, this wavelength.

Hi jay,
Yes but so what? Cyanobacteria also have Chlorophyll-a (reportedly they do not have Chlorophyll-b). They also contain a variety of other auxiliary pigments such as various carotenoids, phycobilin, and in some species, the red pigment phycoerythrin.

So should we also analyze the frequency response of these pigments and try to avoid light bulbs containing their associated frequencies?

Furthermore, plants contain the same pigments so the exclusion of this range of frequencies would also be folly.

BGA is not triggered merely by the presence of some arbitrary light frequency. It is triggered by plants response to poor NO3 uptake.

If the bloom or the plants initial response to malnutrition is recognized early enough then a simple addition of KNO3 will solve the malnutrition and will stifle the growth of this bacteria.

Too many people view algal blooms as a consequence of completely unrelated factors instead of as a consequence of poor plant health. Fix the health of the plants and all forms of algae can be kept at bay.

Many times it's very difficult to understand just exactly what the heck we are doing that results in malnutrition. No one appreciates that sad fact more than I, but we've got to stay on the path by holding fast to the basic principles.

Cheers,

 

[jaypeecee]

Hi @X3NiTH

That's fascinating, isn't it? I was aware that cyano had been around for an estimated 3.5 billion years so what you are saying makes sense. Apparently, we owe it to cyano for providing the oxygen that we breathe.

JPC

 

[jaypeecee]

Hi @ceg4048

Yes but so what? Cyanobacteria also have Chlorophyll-a...

Yes, I mentioned that in my OP.

So should we also analyze the frequency response of these pigments and try to avoid light bulbs containing their associated frequencies?

It's more appropriate to refer to wavelengths as these have already been identified for beta-carotene, fucoxanthin, phycoerythrin, phycocyanin and allophycocyanin. Should we try to avoid light bulbs emitting at these wavelengths, I don't know. I'd like to think we could discuss this.

Furthermore, plants contain the same pigments so the exclusion of this range of frequencies would also be folly.

My understanding is that plants may contain these pigments but they are not critical to the overall health of plants. Is that incorrect?

BGA is not triggered merely by the presence of some arbitrary light frequency. It is triggered by plants response to poor NO3 uptake.

It is not an arbitrary wavelength. 620nm happens to be the wavelength at which cyanobacteria absorbs most of its light, this corresponding to the absorption peak of phycocyanin. Although it absorbs light at the chlorophyll a peak of 430nm, its photosynthetic efficiency at this wavelength is less than that at 620nm. And I am fully aware that lighting alone is not responsible for growth of cyanobacteria.

Your other points will have to wait until tomorrow. In the meantime, I would welcome any feedback you may have on the other related thread that I started recently, Cyanobacteria Identification - At Last (or words to that effect).

JPC

 

[ceg4048]

Hi Jay,
Well, the reason I'm harping on the Chlorophyll-a is because that is the main pigment that photosynthesizing organisms use. Auxiliary pigments must process the light and then pass their energy on to the chlorophyll.

All the other pigments do exactly the same based on their particular frequency response.

Chlorophyll then uses this combined energy to free electrons from their ground state orbit. This is how the electricity that is the Electron Transport Chain (ETC) is initiated. That is the function of the chlorophyll. Auxiliary pigments cannot do this. They all must pass their energy on to the chlorophyll.


Therefore, there is not really any point in trying to address 620nm unless you also first address the light absorption of the chlorophyll itself as well as the energy transfer to the chlorophyll of all the other auxiliary pigments.

This is what I mean by calling the 620nm arbitrary, because you are focusing on this aspect and ignoring all the other wavelengths. I mean surely, you must have studied absorption charts like this:


Please review the response of chlorophyll-a. It starts at 375nm to about 450nm and from about 600nm to 700nm. Of course, this is just the chlorophyll itself, not to mention the response of all the other pigments not named phycocyanin.

Look at the response of the Beta-Carotene. It absorbs into the green. Both plants and BGA have the other pigments that absorb in the wavelengths not covered by the chlorophyll.

I'm not really sure where it is suggested that BGA gets most of it's energy from 620nm, but it doesn't really matter because BGA, like plants, are able to switch to other frequencies very easily.

The point of my argument therefore is: why have you singled out 620nm as a boogieman when BGA clearly is able to use the other wavelengths from blue to red?

Furthermore, if you do eliminate LEDs that emit in the other wavelengths you will be left with virtually nothing and as I said, plants have the same pigments and more so you would be harming plants as well if these wavelengths are eliminated. Even if you were to use bulbs that do not emit 620nm do you really think that BGA would be stopped in any way based on that absorption spectra?

What I'm trying to get across here is that focusing too much on spectra will never solve any of our problems because our problems stem from the overabundance of the total energy of our lights.

Hope this clarifies.

Cheers,

 

[jaypeecee]

Hi @ceg4048

I mean surely, you must have studied absorption charts like this...

Yes, of course. Many of them.

What I'm trying to get across here is that focusing too much on spectra will never solve any of our problems because our problems stem from the overabundance of the total energy of our lights.

Yes, exactly. I couldn't agree with you more. No wonder we have to pump so much CO2 and ferts into our tanks. Lighting rules the roost. But, along with the excessive PPF, we might as well consider the spectrum at the same time. Dr Bruce Bugbee of Apogee Instruments has demonstrated that too much light in the 430 nm - 450 nm (blue) part of the spectrum, in his words, shrinks plants.

More tomorrow.

If I don't get to bed soon, I will turn into a radish (first plant that came into my mind). Ya gotta laugh, eh?

JPC 🙂

 

[jaypeecee]

Hi @ceg4048

Now that I am feeling a little more refreshed, I have to say that I'm uncomfortable about the way this thread is progressing. I was hoping that we could have a friendly discussion about lighting and cyanobacteria. Perhaps it would be wise to draw the thread to a close? My 'gut instinct' tells me that this would be the right thing to do. But, I would have dearly liked to continue the discussion. Decisions, decisions!

JPC 🙂