What are the root causes of Cyano?

[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

I grew a lot of cyanobacteria and the mats grew everywhere. If the mats were formed to release or gather phosphorous, the approach would seemed to have been a fruitless endeavor on the glass, overflow pipes, and power-heads.

The rapid increase in biomass seems to indicate a cause opposite to a growth limiting nutrient. Instead the growth behavior seems to be a response to an opportunity.

I suppose we must continue to pool our experiences and thoughts on “cures” in our search to understand cyanobacteria mat formation. Your description of what could be happening under a mat is intriguing!

 

[Dan_P]

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

Until you find the article, here’s one that might interest you and other cyanobacteria fans

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.1995.tb03051.x

 

[Hans-Werner]

@Lasse,

I am sorry but I can´t follow your line of argumentation. I did some microscoping and I know a bit about algae and bacteria. The wine red mat forming cyanobacteria is a Oscillatoria sp. or a very closely related genus. It is not Spirulina. The blue green mat forming cyanobacteria is also Oscillatoria sp.. Sometimes Oscillatoria sp. are also brownish and look like felt. It seems that these are usually together with Diatoms forming a mat or biofilm of at least two species. Spirulina looks quite different under the microscope and I never found it forming large mats. I don´t think that we have cyanobacteria in mat-forming and non-mat-forming states but maybe different species or strains. I don´t know cyanos that look like sticks, only diatoms that look like sticks or rods.

Especially I can't follow you about the metals. What metals do you mean? Cyanos are sensitive to copper and excrete organic substances to detoxify free copper to <1% free cupric ions in relation to total copper. Cyanos have a high need for iron. Under aerobic conditions iron is precipitated as carbonate or phosphate. Under anaerobic conditions iron ions are released but may form precipitates again with hydrogen sulfide. With organic acids like citric acid iron forms complexes to dissolve. Bacteria excrete complex forming substances with an extremely high affinity to iron called siderophores. I know that cyanos can grow on certain places that are high in iron oxides (i. e. cement concrete) while other substrates are free of cyanos in the same tank. Maybe also phosphate is bound to the iron oxides but that I don´t know for sure.

We need to talk about specific processes instead of vague ideas and theories to really understand the mechanisms working when for example nitrate is added I think.

 

[Dan_P]

@Lasse,

I am sorry but I can´t follow your line of argumentation. I did some microscoping and I know a bit about algae and bacteria. The wine red mat forming cyanobacteria is a Oscillatoria sp. or a very closely related genus. It is not Spirulina. The blue green mat forming cyanobacteria is also Oscillatoria sp.. Sometimes Oscillatoria sp. are also brownish and look like felt. It seems that these are usually together with Diatoms forming a mat or biofilm of at least two species. Spirulina looks quite different under the microscope and I never found it forming large mats. I don´t think that we have cyanobacteria in mat-forming and non-mat-forming states but maybe different species or strains. I don´t know cyanos that look like sticks, only diatoms that look like sticks or rods.

Especially I can't follow you about the metals. What metals do you mean? Cyanos are sensitive to copper and excrete organic substances to detoxify free copper to <1% free cupric ions in relation to total copper. Cyanos have a high need for iron. Under aerobic conditions iron is precipitated as carbonate or phosphate. Under anaerobic conditions iron ions are released but may form precipitates again with hydrogen sulfide. With organic acids like citric acid iron forms complexes to dissolve. Bacteria excrete complex forming substances with an extremely high affinity to iron called siderophores. I know that cyanos can grow on certain places that are high in iron oxides (i. e. cement concrete) while other substrates are free of cyanos in the same tank. Maybe also phosphate is bound to the iron oxides but that I don´t know for sure.

We need to talk about specific processes instead of vague ideas and theories to really understand the mechanisms working when for example nitrate is added I think.

My tank was dominated my a Spirulina species that could be red or green. I saw both colors side by side under the microscope. Over time several other species became the dominant, which included Oscillatoria, but I can still find Spirulina occasionally. The mats are a mixture of many organisms, both plant and animal life. Recently a small beautiful blue-green patch starting growing just above the waterline in the sump where it stays wet from splashing. I don’t recognize the filamentous organism but I am guessing it is yet another cyanobacteria.

Cynabacteria are always present in my aquarium, but not the mats. I can always find small numbers of filaments entangled in the macro algae, the detritus, and in the skimmate.

In my system, something stimulates the cyanobacteria to grow quickly into mats. Eventually this bloom ends even with no more intervention than physical removal.

I am in the process of trying to culture cyanobacteria in tank water.

 

[Lasse]

I have done some microscoping and I know a bit about algae and bacteria too. What I have found both in mats and in normal aquarium is - as you say cyanobacteria probably from the genus Oscillatoria sp. I have identified them with the help of my old school book and the appearance matches with what one gets when you googles Oscillatoria. Maybe my English is bad, but these cyanobacteria I would name sticks. From the swedish "pinnar" - and it will be "stöcke" in german

Twillard at R2R have done some research according to the red mats. He have (with microscoope) shown thar the red mats can be formed by at least one species of Spirullina too. He shown that one way - without using microscope - to differ Oscillatoria mats from spirulina mats is to use H2O2. Oscillatoria will be destroyed fast but spirulina whitstand H2O2 more. You can find his threads here, here, here and here. The last one is huge. I have no reason to doubt his conclusions.

I can´t see that I have mentioned Copper at all in my post. I wrote that some metals form metal-phosphate compounds in aerobic conditions. I do not understand why you doubt that. Calcium, aluminum or iron is used in every waste water treatment plant in order to percipate PO4 from the water. The same do we with help of GFO as an example. This is a natural process taking place in every sediment all over the world. It is also wellknown that anaerobic conditions with hydrogen sulphide production breaks this chemical bounds and release PO4 (and the metal in question) into the water column.

I know that nitrate work in this way in anaerobic sediment in natural freshwater systems (there is some very good research that have been done of this in Sweden). I have been working with anaerobic systems both in waste water treatments plants and fish farms and it is up to you to argue

vague ideas and theories

when I transform this experiences to equal situations in our aquariums.

I do not doubt your statement but - what I´m saying - it is not the only explanation and it not include why NO3 addition can help in order to fight cyanobacteria mats.

Sincerely Lasse

 

[Hans-Werner]

Lasse, I do not doubt your statements. Sometimes I only have problems to follow your argumentations because more than half of the periodic system is "metals" and the chemical properties are very different. While under aerobic conditions the metal iron is oxidized and forms hydroxides or carbonates copper is also a metal but it stays in solution. I have problems to know which metals you are just thinking about. It is easier to talk about a specific metal and a specific reaction instead of "metals".

Oxidation or reduction in connection to binding or release of phosphate is not true for calcium phosphate. The solubility of calcium phosphate depends from the mineral, whether it is freshly precipitated calcium phosphate or aged/old calcium phosphate and it is dependent on pH. It is not dependend from redox state since neither calcium nor phosphate are reduced or oxidized. Calcium is no transition metal.

Lasse, I estimate you very much as a skilled aquarist with a lot of knowledge and good ideas. I would like to follow your argumentation but sometimes I have difficulties because English is not my mother tongue and it would be easier for me if the argumentation sometimes would get more specific.

 

[Hans-Werner]

Lasse, do you know which one is disturbed by nitrate, Spirulina or Oscillatoria? Maybe we are talking about different problems with different kinds of cyanobacteria? Since the sensitivity to H2O2 seems to be different maybe their senstitivity to nitrate is also different? To discuss the problems together as "problems with cyanos" may cause confusion.

You are right that nitrate may disturb the formation of sulfide since nitrate is used for respiration by bacteria before sulfate is used. In this way nitrate can inhibit the formation of sulfide from sulfate by respiration. But how does that impede or disrupt cyanos? Is it because nitrate is an oxidant like H2O2 is? I don't know.

I think I rarely have nitrate in my tanks and I have only found Oscillatoria as mat forming cyanos with my microscope. I have found Spirulina only as single short spirals, never as mats. But more than 2 decades ago I did more experimentation with nitrogen additions and I had ca. 20 ppm of nitrate and nevertheless had wine red mats of cyanos. At this time just as nowadays I had and have low phosphate concentrations and some problems with cyanos. This has led to my firm believe that cyanos have more to do with phosphate than with nitrate. Since my experiments with cement concrete in reef aquaria I am quite convinced that the problem is iron phosphate, precipitated in "detritus" (in German "Mulm") or bound in cement concrete since cement is quite rich in iron oxides.

 

[Lasse]

The enzymatic process of bacteria in order to gain P – I thought it was only valid for obtaining P from organic compounds? Do you know any examples of bacterial enzymatic release of PO4 from inorganic bound PO4?

I´m not a native English speaker either and to have a Swede and a German to understand each other with help of English can be a little difficult

I´m not a scientist but I know a lot of science and one of my tasks in life is to try to explain science fact in a language that normal educated people understand – not every time with explanations that will pass a previewed article but with explanation that make people understand the underlying processes. It means that I sometimes will be a little “scientific” vague. The reason why I use some metals was that I did not want to come into a discussion about particular metals but the most common is iron bound phosphate – and in the case of saltwater and freshwater with a lot of calcium – calcium bound phosphate. I´m pretty sure about hydrogen sulphides importance in the process of release PO4 from iron bound phosphate – it is a known process. If hydrogen sulphide can release PO4 from calcium- PO4 compounds or not – I´m not sure but the process below the mats (after denitrification – read NO3 free anaerobic condition) will lower the pH and lower pH release the bounds between calcium and PO4. For the book – denitrifying below the mats will rise the pH between the mat and substrate. It is the process afterwards (after NO3 is zero) that lower the pH. In this case NO3 will act as a limiter too - according to release of PO4 from calcium-PO4 compounds. As long there is NO3 – there is denitrification -> higher pH.

However - I agree with you that it is probably the absence of free PO4 in the water column that triggers the mat formation. What we probably disagree about is how the cyanobacteria use the mats in order to gain PO4 which are inaccessible for other photosynthetic organisms.


All times that I have had red cyanobacteria mats in my aquaria – rising the NO3 level and disturb the mats as much as possible works. I have seen red cyanobacteria mats in aquarium with high NO3 level and high PO4 levels. If these cyanobacteria have been another species or not – I do not know. But yes – it can be different methods needed if it is spirulina or Oscillatoria you combat.


We are also often only debating limitation of P or N – often forgetting other compounds like iron. If my theory is valid – iron will be released to by the hydrogen sulphides division of iron-phosphate compounds into iron compounds and free PO4.


According to mats growing on the glass or equipment – I have seen that too in some aquaria. Never in my own. But the presence of bound PO4 at the surface of equipment or glass cannot be ruled out – or it is another species.


I think that in the future need to decide which type of cyanobacteria we combat. Twillards test with H2O2 can help us here. If small concentration of H2O2 destroy the cyanobacteria – not spirulina – if it will not be destroyed -> spirulina.


Sincerely Lasse

 

[Hans-Werner]

Lasse, like mentioned above: you know that it are bacteria that cause karies and destroy your teeth if you don't clean and take care of them. It is exactly this process. Bacteria realease organic acids to dissolve for example hydroxyapatite in the case of your teeth. In fact this may be a quite widespread process. Plant roots exudate organic substances into the "rhizosphere" to nourish bacteria that dissolve nutrients like iron and phosphate from insoluble minerals. These are not enzymatic processes but only a decrease in pH (again bear karies in mind) that render calcium phosphates soluble.

With iron phosphates it is different I think. This is the process you described taking place in sediments: iron(III) is reduced to soluble iron(II) and iron and the bound phosphate are both released into the water in this way, "recycled nutrients" for the planktonic spring bloom.

The enzymatic release of orthophosphate from organic phosphates and polyphosphates is something completely different. Most organic phosphates and polyphosphates are water soluble, some even better so than orthophosphates under certain conditions, the only problem is that the molecule size is too big for cellular uptake by organisms. With enzyms like alkaline phosphatase small orthophosphate molecules are released from organic and polyphosphates for cellular uptake, again bacteria being very good in these processes.

 

[Lasse]

I´m not a native English speaker either and to have a Swede and a German to understand each other with help of English can be a little difficult

Note - I miss the smiley when I publish this sentence in post 228. It was writen with with a twinkle in my eye (Swedish for publish with a sense of humour)

Lasse, like mentioned above: you know that it are bacteria that cause karies and destroy your teeth if you don't clean and take care of them. It is exactly this process. Bacteria realease organic acids to dissolve for example hydroxyapatite in the case of your teeth. In fact this may be a quite widespread process. Plant roots exudate organic substances into the "rhizosphere" to nourish bacteria that dissolve nutrients like iron and phosphate from insoluble minerals. These are not enzymatic processes but only a decrease in pH (again bear karies in mind) that render calcium phosphates soluble.

Yes - and it can happen in anaerobic conditions between the mat and the gravel if no denitrifacation process taking place.



Sincerely Lasse

 

[Dan_P]

The enzymatic process of bacteria in order to gain P – I thought it was only valid for obtaining P from organic compounds? Do you know any examples of bacterial enzymatic release of PO4 from inorganic bound PO4?

Would you need anything more than a slightly acidic environment to dissolve calcium phosphate? Maybe it’s not so difficult to find such a situation beneath the mat, especially at night.

 

[Lasse]

Once I run a huge freshwater phytoplankton tank in batch mode. The water contain a lot of calcium near the max for freshwater. Just before the lights turn of - we measured pH of around 9.5 and zero I PO4. The following morning - pH around 7 - 7.5 and rather much PO4. Still the same water. End of day pH around 9.5 - PO4 zero. Next morning - low pH but rather much PO4. And so on. The tank was clean an very low bacterial action.

Sincerely Lasse

 

[Dan_P]

Once I run a huge freshwater phytoplankton tank in batch mode. The water contain a lot of calcium near the max for freshwater. Just before the lights turn of - we measured pH of around 9.5 and zero I PO4. The following morning - pH around 7 - 7.5 and rather much PO4. Still the same water. End of day pH around 9.5 - PO4 zero. Next morning - low pH but rather much PO4. And so on. The tank was clean an very low bacterial action.

Sincerely Lasse

The pH cycle seems to parallel that of saltwater aquaria.

 

[John Hanna]

Once I run a huge freshwater phytoplankton tank in batch mode. The water contain a lot of calcium near the max for freshwater. Just before the lights turn of - we measured pH of around 9.5 and zero I PO4. The following morning - pH around 7 - 7.5 and rather much PO4. Still the same water. End of day pH around 9.5 - PO4 zero. Next morning - low pH but rather much PO4. And so on. The tank was clean an very low bacterial action.

Sincerely Lasse

I believe in this scenario you entered the death phase of the algal life cycle. The general trend is for pH to continue increasing due to oxygen production from photosynthesis until a limiting nutrient is observed, self shading commences or the algae starts to die off. You can also induce self-flocculation from high pH if the conditions are just right, where pH can exceed 10+. The night time stages are consistent with a lack of photosynthesis, however the last case where the pH is lowest in the morning, you will probably observe a low oxygen content and poor algal health/low photosynthesis - the indication of entering the algal death phase, which then started to release phosphate as cells lyse or breakdown.

John

 

[Hans-Werner]

Lasse, thank you for not loosing you humour with me!

Yes - and it can happen in anaerobic conditions between the mat and the gravel if no denitrifacation process taking place.

It is also possible under aerobic conditions. Only decreasing the pH with organic acids can dissolve phosphate deposits as you noticed in your freshwater phytoplankton tank (here with CO2 excreted at night).

I have a second similarity to karies: It seems that sometimes glucose is used to fight cyanos, apparently sometimes with success. I have not tried it myself yet and I don't want to recommend it. I think it might be dangerous especially for shrimps. With the addition of glucose also heterotrophic bacteria can produce organic acids. Maybe heterotrophic bacteria dissolve the phosphate deposits in this way and worsen conditions for cyanos.

 

[Dan_P]

The premier test of an idea for what triggers cyanobacteria growth is to deliberately create a bloom. Making one happen reliably in a small aquarium or a jar would be strong support for the idea.

How you stop a bloom and get rid of it would require another set of experiments.

Does anyone have controlled experimental results?

 

[Hans-Werner]

It depends from your demands. I think if you supply a tank with fresh coral rubble/sand (natural phosphate load) or coral rubble/sand with a high phosphate load or life sand and you then start to supply it with amino acids (N and organic C only, no P) or maybe low concentrations of ammonium (N only) you will reliably get cyano blooms. Always when you take substrates with significant phosphate loads you will get cyano blooms under these circumstances. Maybe you also will get cyano blooms under different circumstances but in my experience this will be the most reliable one.

It is correct that cyanos can grow onto glasses or maybe even only on glasses. The question is whether the glas was really clean before the cyanos grew or whether the cyano film has contact to other substates and only grows onto the glas. Algal films and even thin layers of precipitates enriched in phosphates may be great cyano substates too. I doubt that cyanos will form mats on substates really free of phosphates (including precipitates). This could be the control group.

 

[Hans-Werner]

Dan, I have just read a bit in your link above. It is not so unusual that Oscillatoria is moving into the substate in the afternoon. This article describes that it shows fermentation there and excretes organic acids like acetate. I watched this behavior under high nitrate - low phosphate conditions. My explanation was that in the afternoon after several hours of growth the phosphate stores of the cyanobacterial mat were exhausted. To protect itself from excess illumination under low nutrient (P) conditions and to take up new phosphate the cyanos went underground. In the interstitial water the phosphate concentration is elevated anyways but the cyanos can also excrete organic acids to make further phosphate available.

 

[Lasse]

In my aquarium - cyano mats always have more or less disapaer during night and established itself the next morning. I read somewhere that the mats contain starks and/or sugar. My thoughts for going down during night has been that they use the energy in the mats in order to reproduce.

There is a question of N to. Sometimes zero in NO3 trigg mat building. These cyanobacteria have no heterocysts - they can not by them self fixate N. However - and here it's come again - if they can create an anaerobic condition below the mats - they can work together with fixating anaerobic bacteria and fix the nitrogen.

I agree that probably is low organic P in the watercoloumn that is the most important reason for trigging mat building but IMO - per automatic - the water between the substrate and mats will be om anaerobic very fast.

Sincerely Lasse

 

[Lasse]

Compounds with Iron and PO4 are - as I know PH stable. If the mat building cyano bacteria can utilise this bound PO4 - the only pathway for this is through creation of hydrogen sulphide as I have proposed. In order to utilise calcium bound PO4 - I think that both my and Hans Werner pathways are possible.

Sincerely Lasse