What are the root causes of Cyano?

[Ldballoon4]

So, what are the conclusions?
Low Po4 = Cyano
Higher NO3 leads to Cyano
Cyano is cyclical, therefore, you will have it later no matter what?
high nutrients and low flow is the main cause?
Blow out your rocks and sand frequently?
Or, dose Chemi Clean and call it a day?

 

[brandon429]

The long running cure threads for cyano are the ones where tank cleaning causes compliance

Most of the parameter-adjusting approaches tracked have failed. I believe some were linked here prior as well for study.

The cause seems to be detritus stores in rocks and or sand, parameter adjusting or chemi clean is merely suppressive. It will not cure nor sustain more than occasionally... Cyano and cousins are environmentally exchanged between aquariums and terrestrial/other aquatic zones so they will get in from time to time, whether they aggregate and take over we find linked to detritus stores more than anything- it's why no test params are used to cause cures in the thread below.

Works cited:
https://www.reef2reef.com/threads/the-official-sand-rinse-thread-aka-one-against-many.230281/page-18

 

[Sallstrom]

Most of the parameter-adjusting approaches tracked have failed. I believe some were linked here prior as well for study.

The cause seems to be detritus stores in rocks and or sand, parameter adjusting or chemi clean is merely suppressive. It will not cure nor sustain more than occasionally... Cyano and cousins are environmentally exchanged between aquariums and terrestrial/other aquatic zones so they will get in from time to time, whether they aggregate and take over we find linked to detritus stores more than anything- it's why no test params are used to cause cures in the thread below.

Works cited:
https://www.reef2reef.com/threads/the-official-sand-rinse-thread-aka-one-against-many.230281/page-18

Maybe you don't hear about all the tanks that don't get cyano due to parameter-adjustusting because they won't need a "help with cyano-thread" on R2R?

 

[JasPR]

If been at this hobby for a long long time! And I've made ALL the amateur mistakes and had more than a few epiphanies along the way. In 2019 we know a lot. But due to the number of new people entering the hobby each year-- many things need to be relearned by the next generation. That's part of the hobby. So to being with the most basic concept-- an aquarium is a box of water. A box that we put living things into. As a result of that biological presence, pure water begins to do things-- build up metabolites and nitrogenous waste products, carbon dioxide and other misc. organics. we can convert it to less harmful things but still, the end products tend to pile up in the water column over time. The second major thing that happens is due to biological activity, certain elements are 'used up' or impacted in the way of reduction. The reason for this ramble is to say-- no one will ever invent a magic pill or plugged in wiz bang that can change those two realities of a closed box of water. Bacteria is one of those things that is 'intimate' to the first rule-- as things build, bacteria proliferate. One species is that primitive bacteria we call red slime. Therefore, the very best and easiest way to deal with red slime proliferation is to RESET the baseline on those things that have built up-- one experiment I did years ago now, was to step water changes up to 15% a week * as an experiment. It was truly remarkable to see, in such a short period of time, the changes in the look of the 440 gallon tank. The sand became white again, just like it looked the day the tank was set up. The rock and artificial coral returned to its original color-- and that general worn and drab look of the aquascaping once again 'popped' with a sense of brightness. The red slime? gone, gone, gone.

 

[Belgian Anthias]

Bentic cyano forming microbial matt's grow in combination with other organisms. Within such a matt the community works together. Dying cells will be recycled and remineralized within the matt providing building materials for new growth. Such a matt may become partially undependable of the environment for a period of time. Cyano may deliver organic carbon to the community to supplement the loses during remineralisation and may deliver supplemental nitrogen to the community by leaking ammonia. Once they have formed one can not battle such matt's by limiting nutrients without harming all other live present in the closed system. Removing the matt's manually is the best way to solve this ( and using an effective germicidal lamp (UV) while doing it and the day after) .

 

[brandon429]

Salstrom

The claim is based solely on lack of work threads here using alternate means. A work thread inviting cyano challenges to be publicly worked can be started at any time to provide alternate proofs.
I’m aware of the big cyano thread here/200 pages where people are testing invaders to see if it’s cyano or spirulina/TWilliards thread but it’s not a works thread with updates on fixes, we need that kind of thread momentum to inspect water tuning options however / someone just needs to actually guide the submitted tanks to full restoration.

I do see some hits and misses with nutrient tuning, on other forums etc. when they update on month 9 like our example thread it’s usually back again. If they chemi clean, and leave detritus, it’s back later on most updates

If they use fluconazole to kill gha, and leave detritus, then a cyano invasion takes place in a few months.

That’s the trend=stamped it.

The caveat: nobody with a 200+ gallon tank wants to rip clean it to beat cyano, so, we still need better cures and water-tuning, when perfected, will be very important for large tankers. In the meantime, I recommend anyone building a large home aquarium consider the impacts of an inaccessible sandbed or an inaccessible (for cleaning) rock arrangement.

If you want to hedge your invasion bets regarding matted invaders, account for detritus stores in your system.

It’s not about param tuning at all, says the total absence of work threads demonstrating the claim (which doesn’t mean some initial temporary kills of target aren’t logged by N and P tuning, they are, sparsely, so work on that detail and make an eighteen pager of examples)

 

[Sallstrom]

Salstrom

The claim is based solely on lack of work threads here using alternate means. A work thread inviting cyano challenges to be publicly worked can be started at any time to provide alternate proofs.
I’m aware of the big cyano thread here/200 pages where people are testing invaders to see if it’s cyano or spirulina/TWilliards thread but it’s not a works thread with updates on fixes, we need that kind of thread momentum to inspect water tuning options however / someone just needs to actually guide the submitted tanks to full restoration.

I do see some hits and misses with nutrient tuning, on other forums etc. when they update on month 9 like our example thread it’s usually back again. If they chemi clean, and leave detritus, it’s back later on most updates

If they use fluconazole to kill gha, and leave detritus, then a cyano invasion takes place in a few months.

That’s the trend=stamped it.

The caveat: nobody with a 200+ gallon tank wants to rip clean it to beat cyano, so, we still need better cures and water-tuning, when perfected, will be very important for large tankers. In the meantime, I recommend anyone building a large home aquarium consider the impacts of an inaccessible sandbed or an inaccessible (for cleaning) rock arrangement.

If you want to hedge your invasion bets regarding matted invaders, account for detritus stores in your system.

It’s not about param tuning at all, says the total absence of work threads demonstrating the claim (which doesn’t mean some initial temporary kills of target aren’t logged by N and P tuning, they are, sparsely, so work on that detail and make an eighteen pager of examples)

If you want to address me, please press "replay" or use @ and spell my name correctly. Otherwise I might miss to answer.

I just don't understand why you need to write that another way than yours don't work. Tuning nutrients works fine in the 10+ tanks I'm responsible for at my work. Why can't we just accept that some aquarists manage to keep cyanobacteria away by adjusting nutrient levels etc and some clean out all detritus to get rid of the same problem. Isn't it great that there's different ways to go?

/ David

 

[Hans-Werner]

Not only to get P - also to get N or trace metals. When the mats is formed - you will have a self playing piano according to macro nutrients and micro nutrients.

Particular and organic phosphates are rather stable and will not by themselves transfers to orthophosphate IMO. You stated earlier that it need a certain enzyme in order to do that. If different organism is able to make this for their own consumption - that is one thing - but we all the time get orthophosphate in the water column (read unused orthophosphate). My question is therefore - where comes the orthophosphate in our water column from if it not is from the bacteria driven mineralisation process of organic matter?

Sorry for my late reply. Cyanos can´t get N in the same way they get P or Fe. To dissolve particulate Fe or P it is sufficient for cyanos to excrete organic acids. The bacteria in your mouth do this every day to get the particulate phosphorus that your teeth are finally. To keep them in check you clean your teeth and try to remineralize them with antibacterial fluoride. The bacteria in your mouth need sugar or other carbohydrates to produce organic acids. Cyanos don't even need this, they just need some light and some CO2 or bicarbonate to produce organic acids. That is a big advantage for cyanos over heterotrophic bacteria.

N doesn't form particulate precipitates and the dissolution of particulate P and Fe has nothing to do with mineralization, rather the opposite, forming complexes with organic acids. Most particulate phosphate is orthophosphate in an insoluble form like calciumphosphate. The fish bones in the flake and granular fish food is orthophosphate in an insoluble form. Organic acids make it soluble. Fe is dissolved in the same way. From Fe phosphates even both nutrients may be generated at the same time.

 

[Dan_P]

Since we are still discussing and debating this topic, I assume that we still don’t know how to prevent or stop the occurrence of cyanobacteria mats.

Also, it seems that the notion of nitrate/phosphate balance is being applied to a lot of different issues these days. Anyone know how this got started?

 

[John Hanna]

My favourite quotes and in my opinion most important points of this thread:

What I have learned during all my years trying to manipulate biological systems can be summarized in some few sentences and some of the most important (for me) will following here

1. The nature is energy conservative – it will in the first place chose the pathway there the organism gains most and with the lowest energy input. However, one important organism exclusion – human beings of today
   
2. If there is a lack of a needed (in the growth or survival process) off certain compound or substance in our measurements – that compound or substance is the limited factor and/or the form that will be used in first place
   
3. The processes of nature are logical and understandable – when we do not see that – it’s a lack of logic and understanding in our heads.
   
4. The evolution is not primary based on which genes or behaviour that suit the organism best in a given environment – its instead based on which genes or behaviour that can give any disadvantages in a given environment – those the evolution can happen very fast because these genes or behaviour can be lethal during new or changed environment.

I always try to have these four – for me important sentences – in my head when I run into problems or questions that I have not crashed into before. (Yes – it’s the right word because these situations mostly appear in chaotic situations )

With this in my mind it´s easy for me to accept that NH4/NH3 is the preferred nitrogen species for zooxanthella’s (and other algae) but it’s also understandable that NO3 can work as a nitrogen source for zooxanthella because it´s naturally the most common inorganic nitrogen species in our oceans (with exception for N2 gas) and normally follow the pattern with low levels NO3 and high levels of chlorophyll. Yes, I know there it is some part of the ocean there this pattern is not true – but it seems like this area instead are growth limited by iron. Here is a very god review of the nitrogen cycle in the oceans.

However – what I´m not understand is how it (by itself) can be toxic for some coral species. Certain concentrations – yes but the molecule by itself? I have been told many times that NO3 is toxic for corals – but never seen any evidence of this. If there are new studies showing this – I would love to see these and to see during which circumstances.

@Hans-Werner By the way -for me it seems a little bit odd to use urea as a nitrogen source in a coral system. In a aqueous solution (together with bacteria) urea (CO(NH2)2 is one of the most pH rising nitrogen containing substance I know. It will rapidly be breakdown to carbon dioxide and NH4/NH3 by heterotrophic bacteria and hence rise the pH. Rising pH – more toxic NH3 will be formed.

Sincerely Lasse

Limiting nutrients only removes competition and favors diazotroph cyano growth the moment nutrients become available as Trichodesmium growt is normally surpressed by phytoplankton growth in the battle for phosphate and other building materials. When phytoplankton growth is eliminated or limited due to the lack of sufficient nitrogen compounds most phosphate becoming available can be used by N2 fixing cyano's. Also non N2 fixing cyano's may bloom. Keeping on a minimum ( measurable) level of nutrients makes it possible to keep control.
Controlling phytoplankton growth may not only control cyano's but also the secondary and primary food chain.
In the early days, marine aquaria where kept containing more than 200 ppm nitrate and an unknown phosphate level. Some aquaria had cyano outbreaks, others did not.

If I could summarise a generic cause for the dominance of a given organism and apply the KISS rule the reasons would be as follows:

1. The abiotic environmental conditions (light, nutrients & temperature) are favourable for initial colonisation and reproduction.
2. There is no organism that can predate and/or reproduce in sufficient numbers to control the emerging population
   
3. The organism is able to self sustain it's population using the existing abiotic conditions and the now modified ecology where it can remain unaffected by it's own die off i.e. the nutrients lost from old organisms is recycled into new organisms.

In the case of point 3, the organism becomes very difficult to control because the other organisms such as coral (K selected organism) must compete with a organism such as cyano that can reproduce rapidly (an R selected organism) and consume the same key elements of growth - nutrients and light. As nutrients and light continue in an aquarium setting, this loop becomes a positive feedback system, where growth will continue until one factor becomes limiting or self induced conditions change abiotic conditions required to continue growth. Typically in nature this system would eventually crash the existing ecology and potentially its own species or create a monoculture for the regions where it can grow and maintain populations.

So why does such an outcome occur in aquariums - because cyno is always present (though initially in low concentration) and had conditions at one stage to outcompete or reproduce faster than its competitors + lacked sufficient predation to keep its population controlled. The reason ecosystems like the amazon or natural reefs work is because every aspect of both abiotic and biotic conditions has a not only one species but numerous types that each target various niche and microcultures present. When considering the dominance of an unwanted species like cyano, two fundamental breakdowns of aquarium ecosystems are the diversity or similar species and the lack of keystone predators. Both of these aspects become essential for maintaining an ecosytem 'entropy' (apologies if that term was incorrect).

So in my eyes, while chemical adjustment may assist in retaining balance, this can only be truly achieved if the ecosystem is then built back in a way that has sufficient competitors and predators to maintain a homeostatic trophic ecology.

I believe the single biggest restraint in modern aquaria is the lack of these two factors. Seeing as how cyano is an autotroph and a primary producer, speaking from a natural resolution perspective, the only fix can come from an equal trophic group such as phytoplankton (as @Belgian Anthias suggested), which then support favourable consumers from higher trophic groups (as cyano is more unfavourable than say nannochloropsis). While chemical changes may work, the underlying result in my opinion would be because the ecology has been restructured NOT because of elemental concentrations. I agree that long term, the ratio of nutrients may favour some species, but given tanks have been with and without cyano in both high and low nutrient concentrations, it supports the fact that ecology has shifted to a less erratic and more balanced web.


John

 

[Hans-Werner]

Since we are still discussing and debating this topic, I assume that we still don’t know how to prevent or stop the occurrence of cyanobacteria mats.

Since it is difficult to avoid fluctuations in nutrient concentrations, especially phosphate, it is difficult to avoid cyanos. Additionally many substates like coral gravel, some araganite sands, rocks etc. may be quite rich in phosphate. Cyanos will bloom on these substates as soon as the water gets low in phosphates. So cyanos are hard to avoid. To get rid of them it needs patience and continuity, two things that are not easy to achieve since most reefers try to get rid of cyanos by altering things.

 

[Dan_P]

My favourite quotes and in my opinion most important points of this thread:





If I could summarise a generic cause for the dominance of a given organism and apply the KISS rule the reasons would be as follows:

1. The abiotic environmental conditions (light, nutrients & temperature) are favourable for initial colonisation and reproduction.
2. There is no organism that can predate and/or reproduce in sufficient numbers to control the emerging population
   
3. The organism is able to self sustain it's population using the existing abiotic conditions and the now modified ecology where it can remain unaffected by it's own die off i.e. the nutrients lost from old organisms is recycled into new organisms.

In the case of point 3, the organism becomes very difficult to control because the other organisms such as coral (K selected organism) must compete with a organism such as cyano that can reproduce rapidly (an R selected organism) and consume the same key elements of growth - nutrients and light. As nutrients and light continue in an aquarium setting, this loop becomes a positive feedback system, where growth will continue until one factor becomes limiting or self induced conditions change abiotic conditions required to continue growth. Typically in nature this system would eventually crash the existing ecology and potentially its own species or create a monoculture for the regions where it can grow and maintain populations.

So why does such an outcome occur in aquariums - because cyno is always present (though initially in low concentration) and had conditions at one stage to outcompete or reproduce faster than its competitors + lacked sufficient predation to keep its population controlled. The reason ecosystems like the amazon or natural reefs work is because every aspect of both abiotic and biotic conditions has a not only one species but numerous types that each target various niche and microcultures present. When considering the dominance of an unwanted species like cyano, two fundamental breakdowns of aquarium ecosystems are the diversity or similar species and the lack of keystone predators. Both of these aspects become essential for maintaining an ecosytem 'entropy' (apologies if that term was incorrect).

So in my eyes, while chemical adjustment may assist in retaining balance, this can only be truly achieved if the ecosystem is then built back in a way that has sufficient competitors and predators to maintain a homeostatic trophic ecology.

I believe the single biggest restraint in modern aquaria is the lack of these two factors. Seeing as how cyano is an autotroph and a primary producer, speaking from a natural resolution perspective, the only fix can come from an equal trophic group such as phytoplankton (as @Belgian Anthias suggested), which then support favourable consumers from higher trophic groups (as cyano is more unfavourable than say nannochloropsis). While chemical changes may work, the underlying result in my opinion would be because the ecology has been restructured NOT because of elemental concentrations. I agree that long term, the ratio of nutrients may favour some species, but given tanks have been with and without cyano in both high and low nutrient concentrations, it supports the fact that ecology has shifted to a less erratic and more balanced web.


John

John, and of course everyone else, can we continue along your line of reasoning and try answering two questions

1) Why are we plagued by benthic cyanobacteria rather than blooms of pelagic species?

2) Is the cyanobacteria the organism that first colonizes the surface where the mat eventually forms or is there a community that first colonizes the surface that makes it amenable to cyanobacteria colonization?

I have more questions but let’s see where these two lead.

Dan

 

[Sallstrom]

John, and of course everyone else, can we continue along your line of reasoning and try answering two questions

1) Why are we plagued by benthic cyanobacteria rather than blooms of pelagic species?

2) Is the cyanobacteria the organism that first colonizes the surface where the mat eventually forms or is there a community that first colonizes the surface that makes it amenable to cyanobacteria colonization?

I have more questions but let’s see where these two lead.

Dan

My guesses

1. Most phytoplankton end up in skimmers, filter bags, filter feeders and on the bottom.

2. First visible organism that starts growing on new surface areas is usually diatoms. But might be Cyanobacteria in some tanks. Perhaps depends on what status the tank is in.

About how nutrient adjustment started as a cure for Cyanobacteria, at least in Sweden, was when ULNS and the Zeovit method was popular. Many aquarists, me included, had cyano problems when keeping nutrients very low by adding a carbon source and zeolite filters. We started experimenting with adding nitrate and found that in many cases the Cyanobacteria went away after a while with a bit higher nitrate.

 

[Dan_P]

My guesses

1. Most phytoplankton end up in skimmers, filter bags, filter feeders and on the bottom.

2. First visible organism that starts growing on new surface areas is usually diatoms. But might be Cyanobacteria in some tanks. Perhaps depends on what status the tank is in.

About how nutrient adjustment started as a cure for Cyanobacteria, at least in Sweden, was when ULNS and the Zeovit method was popular. Many aquarists, me included, had cyano problems when keeping nutrients very low by adding a carbon source and zeolite filters. We started experimenting with adding nitrate and found that in many cases the Cyanobacteria went away after a while with a bit higher nitrate.

Interesting. Are you tracking organics? In my small scale experiments, it seems that carbon dosing may elevate organics. At this point I cannot distinguish dissolved organics from particulates. I might just be detecting elevated bacteria count which unfortunately I don’t measure. I need way more data to comment more than “seems”.

I would love to test this notion of elevated nitrates helping to reduce cyanobacteria but I need to learn how to grow cyanobacteria, though even then I might not be able to reproduce the aquarium conditions on a small scale.

Thanks for the insight!

 

[Sallstrom]

Interesting. Are you tracking organics? In my small scale experiments, it seems that carbon dosing may elevate organics. At this point I cannot distinguish dissolved organics from particulates. I might just be detecting elevated bacteria count which unfortunately I don’t measure. I need way more data to comment more than “seems”.

I would love to test this notion of elevated nitrates helping to reduce cyanobacteria but I need to learn how to grow cyanobacteria, though even then I might not be able to reproduce the aquarium conditions on a small scale.

Thanks for the insight!

Organics as in organic carbon? We've just started testing at Triton lab, their N-DOC tests. Only tested once, so I can't say anything yet. But started dosing ethanol in two of our tanks after the first test(we were low in organic C compared to their set point) and now we're waiting for the results on the second one.
Will be interesting to see if it's possible to see any trends or connections between organic carbon-Cyanobacteria-nutrients.

 

[Dan_P]

Organics as in organic carbon? We've just started testing at Triton lab, their N-DOC tests. Only tested once, so I can't say anything yet. But started dosing ethanol in two of our tanks after the first test(we were low in organic C compared to their set point) and now we're waiting for the results on the second one.
Will be interesting to see if it's possible to see any trends or connections between organic carbon-Cyanobacteria-nutrients.

Yes, sorry, dissolved organic carbon.

You have to keeps us posted on the organic carbon and cyanobacteria correlation.

 

[Lasse]

Cyanos don't even need this, they just need some light and some CO2 or bicarbonate to produce organic acids.

In this thread I use the word cyanobacteria but means mat forming benthic cyanobacteria. These bacteria we always can see in aquarium water - they look like tiny sticks. But in certain occasion - they suddenly start to form mats and reproduce very fast. I can´t still leave the question – why individually cyanobacteria suddenly start to form mats?

My theory for the moment is that this is a question of available P for growth. If your explanation of how these benthic cyanobacteria can utilize phosphorous sources that are blocked for other photosynthetic organisms is the only one – they would not need the mats IMO. But my idea is that low orthophosphate or a low content of easily bound P trigger the mat formation

What I think will happen under the blanket is a creation of anaerobic zones. During some circumstances these anaerobic zones will create hydrogen sulphide that will split the bounds between metals and PO4 - molecules created earlier because many free metal ions can bind PO4 to a metal-phosphate complex under aerobic conditions. Everyone that have read what I think about fighting benthic mat forming cyanobacteria knows that I in a first try always recommending to rise the NO3 level – why do I this- I do believe that the forming of mats is trigged o lack of P?

The answer is rather complicated – but it has been shown many times that concentration of more than 1-2 ppm NO3 in the water will block the formation of hydrogen sulphide during anaerobic conditions. In order to split the bounds between metals and PO4 – anaerobic conditions are not enough – in order to break the bounds, it is a need of hydrogen sulphide too. Note – even iron can be released this way. Add NO3 and remove as much of the mats every day is normally my first advise. However – it does not always help and the reason for that is probably that it is different species involved. Some have shown that some benthic mat building cyanobacteria will be destroyed of hydrogen peroxide – some will not. The ones that is rather resistant to hydrogen peroxide is a benthic cyanobacteria from the spirulina family. Interesting here – the red colour of some spirulina is due to the forming of a pigment that can serve as an antioxidant!

I will stress that the text above is strongly IMO – have no controlled tests that show this – it is just some experiences and knowledge from other fields that I have put together.


Sincerely Lasse

 

[Dan_P]

In this thread I use the word cyanobacteria but means mat forming benthic cyanobacteria. These bacteria we always can see in aquarium water - they look like tiny sticks. But in certain occasion - they suddenly start to form mats and reproduce very fast. I can´t still leave the question – why individually cyanobacteria suddenly start to form mats?

My theory for the moment is that this is a question of available P for growth. If your explanation of how these benthic cyanobacteria can utilize phosphorous sources that are blocked for other photosynthetic organisms is the only one – they would not need the mats IMO. But my idea is that low orthophosphate or a low content of easily bound P trigger the mat formation

What I think will happen under the blanket is a creation of anaerobic zones. During some circumstances these anaerobic zones will create hydrogen sulphide that will split the bounds between metals and PO4 - molecules created earlier because many free metal ions can bind PO4 to a metal-phosphate complex under aerobic conditions. Everyone that have read what I think about fighting benthic mat forming cyanobacteria knows that I in a first try always recommending to rise the NO3 level – why do I this- I do believe that the forming of mats is trigged o lack of P?

The answer is rather complicated – but it has been shown many times that concentration of more than 1-2 ppm NO3 in the water will block the formation of hydrogen sulphide during anaerobic conditions. In order to split the bounds between metals and PO4 – anaerobic conditions are not enough – in order to break the bounds, it is a need of hydrogen sulphide too. Note – even iron can be released this way. Add NO3 and remove as much of the mats every day is normally my first advise. However – it does not always help and the reason for that is probably that it is different species involved. Some have shown that some benthic mat building cyanobacteria will be destroyed of hydrogen peroxide – some will not. The ones that is rather resistant to hydrogen peroxide is a benthic cyanobacteria from the spirulina family. Interesting here – the red colour of some spirulina is due to the forming of a pigment that can serve as an antioxidant!

I will stress that the text above is strongly IMO – have no controlled tests that show this – it is just some experiences and knowledge from other fields that I have put together.


Sincerely Lasse

Lasse, I am still thinking through your logic, but here is some information about cyanobacteria color.

They can change color. They can be green or red or somewhere in between. The phenomenon is referred to as complimentary chromatic adaptation. It can occur because of the change in available light wavelengths, the organism adopting a complimentary color. Cyanobacteria color change can be induced by available nitrogen. If the cyanobacteria is using ammonia it slows down photosynthesis by changing color to green and absorbing lower energy light. It will need more energy if the nitrogen source is nitrate and will change to red to absorb higher energy light. Check out the reference to validate my recall

For example
https://www.microbiologyresearch.or...est&checksum=E32CFD9FDFFEB426183929816A2361F6

Maybe color of the cyanobacteria can be a diagnostic tool. I have seen both colors in the same cyanobacteria species. The one I have in mind most vividly demonstrating color change was some sort of Spirulina.

 

[Lasse]

Once - I read an article about spirulina production on Hawaii. During growth phase - it was green but just before harvest they did something that turn the spirulina into a red colour. The pigment(s) responsible for the colour change was wanted because they was very good antiradicals. The problem is that I can´t found the article again.

Sincerely Lasse

 

[John Hanna]

John, and of course everyone else, can we continue along your line of reasoning and try answering two questions

1) Why are we plagued by benthic cyanobacteria rather than blooms of pelagic species?

2) Is the cyanobacteria the organism that first colonizes the surface where the mat eventually forms or is there a community that first colonizes the surface that makes it amenable to cyanobacteria colonization?

I have more questions but let’s see where these two lead.

Dan

1. I agree with @Sallstrom here. From a physical point of view, most pelagic types of phytoplankton are going to be filtered, killed from UV or skimmed out. From a predatory view, your unicellular varieties are also going to be consumed more favourably than your filamentous varieties due to size of both the algae and predator. The downsides with UV units, skimmers and filter meshes is you heavily skew this habitat in favour of benthic varieties as they have attachment mechanisms which can prevent their extraction from the reasons mentioned above.

2. While I don't believe they are the only colonisers or necessarily the first, there would be too many factors involved to distinguish this as the dynamics of every tank are different. I would be asking why are they able to maintain populations while others cannot. This has to come back down to diversity and competition, which is artificially altered due to the reasons in point 1.

I would think that low nutrient conditions would be more favourable for them because of storage mechanisms present as well as reproduction methods available i.e. where a unicellular organism only has one cell to divide from, the nutrients for reproduction must come from that cell, whereas a filamentous strand has a host of numerous cells and can also be propagated.

@Lasse, With regard to matting, from my own research with Chlorella vulgaris under high nutrient conditions with Ammonia as the only nitrogen source it was possible to achieve clustering and clumping of cells that was not achieveable in lower nitrogen concentrations. Quite a bizarre experience for what is otherwise a unicellular and solitary organims. The cell quota for nitrogen also increased when using ammonia compared to nitrate with alterations to chlorophyll and cell size. In my case, I suggested this was because the uptake for ammonia was via direct adsorption (externally) and internal transport needed no transformation to another form. When compared to nitrate grown cells, individual cell quotas were lower, while overall cell numbers were higher and I suggested nitrate as a more favourable form despite the energy loss for internal conversion back to ammonia for cell transport using nitrate reductase enzyme. So what I'm trying to say here is that it could also be because the conditions turn more unfavourable when matting occurs. @Dan_P If a colour change is induced to red and this is from a protective mechanism such as astaxanthin, then I would certainly state this as a stress factor perhaps due to a combination of light availability and nutrient conditions at the time. Both nutrient, light and temperature are used as triggers for astaxanthin production on commercial levels.

I would still question if perhaps the addition of nutrients is contributing to a bloom of other algae? My first thoughts on a lack of P content contributing to matting was that it would also likely be required to construct the mats through the formation of various organic structures lipids so may be counter intuitive?

John