What exactly causes BBA? Part 2 - Bacterial imbalance

[AndyMcD]

Following on from the What Exactly Causes BBA? thread, I've been reading some of the scientific literature around the subject and I'd like to make a radical proposal of an alternative cause of outbreaks of black beard algae (audouinella) in planted aquariums. I have listed some of the sources of information at the end of this post.

I believe that the root cause of an outbreak of BBA is due to an imbalance in the bacteria in the aquarium.

There are two major groups of bacteria in aquariums.

The autotrophic, nitrifying bacteria, that convert ammonia to nitrites then nitrates. When a tank is cycled, it is a population of this type of bacteria that need to build up. Autotrophic bacteria convert carbon dioxide into the organic carbon molecules they need to grow. It requires a lot of the energy they generate to do this, meaning that they can only grow and reproduce very slowly.

There are also the heterotrophic bacteria that feed on the waste, converting proteins to amino acids then ammonia. Converting the organic carbon molecules they consume into the molecules they need to grow and reproduce requires much less energy, meaning that their populations can grow much more rapidly than the autotrophic bacteria.

These two types of bacteria compete for oxygen and a surface to populate. In a well maintained aquarium the two types of bacteria are in equilibrium.

Many of the perceived triggers of BBA are similar to the conditions that favour the heterotrophic bacteria and the conditions that inhibit the autotrophic bacteria.

The conditions in the aquarium begin to favour the heterotrophic bacteria if the dissolved organic compounds begin to accumulate (excess food, dead plants, fish waste etc). As with a compost heap, a higher carbon to nitrogen ratio favours the heterotrophic bacteria. Driftwood has a very C/N ratio.

The factors that inhibit autotrophic bacteria include:
- Ammonia and nitrite availability
- Dissolved oxygen levels (with low surface agitation, indirectly this will be most affected by CO2 levels, high plant biomass and fast growing plants. Surface agitation at night may help ensure oxygen always available)
- Bicarbonate availability (formed when CO2 or calcium carbonate (limestone, e.g. ADA Seiryu) dissolves in water. Also affected by CO2 availability. 24 hour low level would ensure bicarbonate always available)
- pH (Nitrifying bacteria prefer a pH range between 7.3 and 8.0. Nitrification will cease if pH drops below 6.0. Addition of limestone may raise the pH, but enable a 1 pH drop and remain above pH 6.0)
- Temperature (optimum range is 25 to 30 deg C. Growth rate decrease by 50% at 18 deg C. Sub-tropical tanks may be more susceptible to BBA. Reason why coldwater tanks can support fewer fish)
- Light (sensitive to blue and ultraviolet light when in the water column)
- Inhibitory chemicals (chlorine and chloramine)
- Nutrients (require phosphates to create the organic carbon molecule ATP via the Calvin cycle)

If any of these factors inhibit the nitrification carried out by the autotrophic bacteria, the level of ammonia / urea in the aquarium will begin to rise.

Studies have been performed that show that some species of algae and heterotrophic bacteria produce organic compounds for the other organism's benefit.

Algae convert CO2 into organic molecules (e.g. ATP) which the heterotrophic bacteria consume.

In return, heterotrophic bacteria create organic compounds that the algae require to grow and re-produce, for example, vitamin B12.

Once vitamin B12 and ammonia / urea are available to the algae, they are able to create the compounds they require to grow and reproduce (orthinine - spermine - spermidine) via know metabolic pathways (the urea cycle and citric acid cycle). See page 13 of http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3476827/

My suggestion is that:
- As C/N ratios rise, the population of the heterotrophic bacteria begin to rise
- If the conditions in the aquarium favour the heterotrophic bacteria, they begin to produce compounds such as vitamin B12
- However, if the conditions in the aquarium act to inhibit the autotrophic bacteria, the concentration of ammonia increases. For example, a reduction in CO2 means, less bicarbonates and indirectly less oxygen to function
- Once the algae are able to consume vitamin B12 and ammonia, they are able to create the organic compounds they require to grow and reproduce

Sources of information:
1. http://www.oscarfish.com/article-home/water/72-heterotrophic-bacteria.html

2. http://www.oscarfish.com/water/71-autotrophic-bacteria-manifesto.html

3. http://www.sciencedaily.com/releases/2012/05/120531165714.htm

4. http://www.researchgate.net/profile/Severin_Sasso/publication/230547610_Mutualistic_interactions_between_vitamin_B12dependent_algae_and_heterotrophic_bacteria_exhibit_regulation/links/0fcfd509536dcb94d6000000.pdf

5. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3476827/

6. http://www.sciencedirect.com/science/article/pii/S004484860600216X

 

[Guest]

If this is true, then the reason we see a correlation between fluctuating CO2 levels and BBA is actually due to low O2 levels which inhibits growth of autotrophic bacteria/microbes.

Low CO2 => decreased photosynthesis => low O2 => inhibited autotrophic microbes => increase heterotrophic microbes => production of specific nutrients => BBA growth

(On a related note, fungi are also heterotrophic organisms. I've noticed a correlation between adding glutaraldehyde and the re-appearance of fungus on wood. The fungus was present for several months, much longer than was expected. Then it suddenly disappeared after glut treatment was ceased and remained for several months. Recently, a week after full glut treatment, the fungus came back in full swing. I interpret that the glutaraldehyde killed off the microbes that colonized the wood and allowed the nutrients to leach out which the fungus feasted on. If true, then this supports the idea that glutaraldehyde is nothing more than a biocide even at such low levels, reducing the numbers of the periphyton on plant leaves which allow them less restricted access to CO2 which results in increased growth rate.)

So if the low O2 hypothesis is correct, then one way to induce BBA is to
1) increase O2 levels
2) suddenly decrease O2 levels
3) observe any effects

Does anyone have an O2 tank that they can artificially inject into the water column?
Warning: O2 levels at ~20ppm will kill fish. Equilibrium O2 concentration is only around 8-9ppm. The O2 added by photosynthesis may result in 10-12ppm, or even higher O2 saturation.

 

[AndyMcD]

Autotrophic bacteria require oxygen and bicarbonate HCO3- to convert ammonia to nitrites/nitrates. The largest source of oxygen in a planted tank is the photosynthesising plants. Bicarbonate ions are formed when CO2 dissolves in water (carbonic acid). Therefore, the population of autotrophic is dependent upon the supply of CO2.

A high, steady supply of CO2 (with a source of ammonia) would lead to a large population of autotrophic bacteria, converting the ammonia to nitrites / nitrates.

If the CO2 supply is reduced, the autotrophic bacteria may be starved of oxygen and become dormant or die. The heterotrophic bacteria can grow and re-produce with less oxygen and so their population continues to increase.

Some heterotrophic bacteria are able to function without oxygen, de-nitrifying nitrites and nitrates to nitrogen gas, which would escape from the tank (which would increase the C/N ratio favouring the heterotrophic bacteria).

Even if the CO2 is brought back to its previous level, it would take time for the autotrophic bacteria to re-gain it's original population size (frustratingly long time to cycle a tank).

Providing there is sufficient organic carbon, the heterotrophic bacteria could take advantage of the increased oxygen supply.

It is estimated that it takes the following time for the population size to double:
- Autotrophic bacteria (ammonia to nitrite) - 7 hours
- Autotrophic bacteria (nitrite to nitrate) - 13 hours
- Heterotrophic bacteria - 20 minutes

Also, if the autotrophic bacteria are not functioning the ammonia /urea concentration would have increased.

Happy heterotrophic bacteria producing vitamin B12 and unhappy autotrophic bacteria not converting ammonia leads to happy BBA, is what I am proposing.

This would suggest that a water change and a clean up should be performed before increasing CO2 after a drop, to remove organic carbon first. CO2 should be increased slowly to give the autotrophic bacteria time to respond.

Glutaraldehyde is used as a bacteriacide in hospitals.

 

[AndyMcD]

Also, this ties in with the recommendation that you should start with a large number of plants to avoid algae, including fast growing ones.

More photosynthesising plants, more oxygen.

Also, fast growing plants must be converting more carbon dioxide to organic carbon (new plant cells) and releasing more oxygen.

 

[dw1305]

Hi all,
It is an interesting argument. I think the problem is that nobody on this forum (and possibly no-body anywhere else) is really qualified to comment.

I'll cover both the <"Red Algae"> (Rhodophyta) that we get in the aquarium.

Staghorn
My gut feeling is that you may be right for Staghorn algae (Compsopogon spp.). I've found that its appearance is definitely preceded by some form of organic pollution, and "organic pollution" is really just another way of saying increased "Biochemical Oxygen Demand" (BOD). A larger BOD would lead to both lower oxygen levels, and higher levels of CO2.

I've recently found a very interesting paper on Staghorn Algae <"Global sampling reveals low genetic diversity within Compsopogon (Compsopogonales, Rhodophyta)">, which suggests that all "staghorn" is genetically similar, and its success is due to its tolerance of a wide range of conditions.

The ubiquitous distribution of Compsopogon in tropical/subtropical regions and its low genetic variation are probably facilitated by the alga's ability to tolerate a wide range of stream conditions and its propagation via asexual spores. Given the findings of previous culture-based studies, morphometric research and field observations, coupled with the results of our study, we conclude there is only a single monospecific genus worldwide and that the species is correctly called C. caeruleus

BBA
Again this is purely anecdotally, but I only tend to get a small amount of BBA on the filter outflow, and on the filter intake sponges. I don't have any proof, but my suspicion is that these are areas where the Ramshorn snails can't graze.

I'm pretty sure the water is fully oxygenated at the filter outflow, they are at the waters surface and a venturi is running, CO2 levels should also be fairly consistent (and close to equilibrium with atmospheric levels).

I don't tend to have a lot of algae of any description in the tanks (they are all heavily planted and have been set-up for more than a year), but this may-be because of grazing by Asellus and snails.

cheers Darrel

 

[Guest]

I only get staghorn on the margins of certain plant leaves (Hygrophila pinnatifida) when they are deficient in potassium. Once I add potassium, it quickly goes a way. I've never had staghorn until I started keeping H. pinnatifida.

 

[AndyMcD]

Before going on holiday, I dripped neat Easycarbo (glutaraldehyde) onto Anubia leaves to kill the BBA.

When I got back, the BBA was thriving. It was worst where the leaves had been burned by the Easycarbo and had begun to disintegrate, where sunshine was hitting the tank (which only happens in the middle of summer).

It made me start to think about whether the bacteria consuming the stressed plant leaves could be linked with the growth of the BBA.

Heterotrophic bacteria will multiply on leaves that are stressed or are dying, breaking them down. They stick to the surface by creating a sticky biofilm. This may be thickest at the leaf edges due to turbulent flow and / or being grazed least at the edges.

When I started to look for scientific papers that discussed relationships between algae and heterotrophic bacteria, there is evidence that this happens.

I now think that:
- the heterotrophic bacteria population was increasing as it consumed the stressed leaves
- the BBA spore had germinated in the biofilm
- the BBA was growing rapidly in the bright sunshine, fixing an excess of carbon dioxide and releasing organic carbon molecules to benefit the heterotrophic bacteria
- in return, the heterotrophic bacteria was producing and releasing the organic compounds the BBA needed to reproduce (e.g. Vitamin B12)

I wonder if a lack of nutrients (potassium) is putting the plant under stress and the heterotrophic bacteria are beginning to accumulate...

 

[Guest]

K deficiency definitely causes a lot of tissue damage in the older leaves which results in algae colonizing these leaves.

 

[AndyMcD]

A diagram to help explain the process I'm proposing.

 

[AndyMcD]

One more point about my BBA holiday experience, while I was away I wasn't able to give the aquarium its daily dose of glutaraldehyde, so reduced the CO2 input (affected availability of O2) and stopped dosing a bacteriacide.

 

[Guest]

Glut kills BBA, which may be the reason for it's sudden appearance when it was no longer dosed.

 

[AndyMcD]

True, particularly when spot dosed at higher concentrations, but daily dosing at low doesn't seem to have as big an effect.


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[Guest]

Even suggested dosing concentrations reduces the amount of BBA.

 

[AndyMcD]

True


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[zozo]

I got the impresion it was the algea parasiting on the leaves and causing the melt.. but it seems to be other way around, indeed very intersting.. 🙂 I only can confirm since i'm still running on the edge with Staghorn and clado. Got it somewhat under control for the most part, but its constantly lurking to hit back and im still not 100% clean. (Never will i guess). Most of the time when i find it, it always around plants melting somewhere.. F.e. had some large patches of floating Ricia smothered by the duckweed,turning white and melting and after closer inspection found the melt deep inside and also hair algae with it.

Also still strugling a bit to get the Potamogeton Gaiy astablishing in my tank. This plant is very delicate, melts very quick for what ever reason, staghorn is always on it's meting tips. Glut doesn't help because this plants hates it and start to melt even faster if glut is used. Staghorn gone but more melt from the glut.

Mini Bolbitis is a plant i just can't get going into a proper transiton in my tank, replaced it for the 3th time with new ones. Old leaves start melting after e few days and turning black, staghorn feasting on it. AFter all old leaves are gone tiny new ones apear, but are so slow it's hard to keep the stag off of it.

 

[AndyMcD]

What I am suggesting is that too much or too little of something is causing the leaf to melt, but once it starts, the heterotrophic bacteria will start to consume it and multiply. The algae in turn is then able to benefit from the heterotrophic bacteria doing well.

This may have a wider impact in the aquarium. Melting leaves disintegrate and add to the supply of organic carbon molecules in the water column and / or in the filter, supplying the heterotrophic bacteria with food. A water change / filter clean would help to reduce this.

JBL recommend in their aquascaping leaflet cutting the leaves off crypts in a new aquarium.

Once a leaf begins to melt it may be best to cut it off as soon as possible to reduce the organic carbon in the water column.

Many more experienced people on this forum have recommended this type of maintenance. All I'm suggesting is that this is helping to minimise the heterotrophic bacteria population that are supplying nutrients to the algae.

 

[Guest]

Mini Bolbitis is a plant i just can't get going into a proper transiton in my tank, replaced it for the 3th time with new ones. Old leaves start melting after e few days and turning black, staghorn feasting on it. AFter all old leaves are gone tiny new ones apear, but are so slow it's hard to keep the stag off of it.

Staghorn on leaves? Probably potassium deficiency. Also, mini bolbitis has very very small submerged leaves, under 2" long.

 

[AndyMcD]

Darrel,

It is an interesting argument. I think the problem is that nobody on this forum (and possibly no-body anywhere else) is really qualified to comment.

I read the What Exactly Causes BBA? thread with interest. The argument for experiments to definitively prove the causes was strong. However, I think that the number of potential causes suggested meant that any experiment would have a huge number of variables, requiring a massive investment of time and money. Also, any results may be far too specific - only valid for one species of fish, one species of plant etc.

Also, although there appeared to be a lot of anecdotal evidence of what triggered an outbreak, very few mechanisms were suggested.

Before starting designing an experiment, I thought it was recommended that you should look into what others had discovered, to try and focus on the critical potential causes.

Although experiments haven't been performed to study the growth of algae in aquariums, quite a few studies have been carried out in other applications: shrimp farming; biofuels and the capture of carbon by marine algae to reduce greenhouse gases.

Try typing "rhodophyta vitamin b12" into Google.

Over the past couple of months I've read around the subject quite a bit, to the point where I felt I could propose an alternative mechanism, which seemed to fit well enough to throw it open to the forum to see if others felt the theory held water. A bit of blue sky, thinking outside the tank!

I didn't expect a definitive answer to this proposed argument. I just wondered what others thought and whether they felt it was a good or bad fit to their personal experience.

 

[AndyMcD]

If you try the following three Google searches, you can see the headlines of the scientific work that has been done:
- Rhodophyta vitamin b12 (shows red algae such as BBA need vitamin B12)
- pseudomonas denitrificans vitamin b12 (shows that a type of heterotrophic bacteria produces vitamin b12)
- pseudomonas denitrificans aquarium (shows the pseudomonas family of bacteria are commonly found in aquariums)

 

[zozo]

Staghorn on leaves? Probably potassium deficiency. Also, mini bolbitis has very very small submerged leaves, under 2" long.

I'm not quite sure what your pointing at!? You mean melting old emersed leaves or slow growth is probably potassium deficiency? Or staghorn on it leaves is potash deficiency?

Anyway if staghorn is establashing for whatever reason my slow growers are the first to show.. In my case the Anubias, all 3 kinds of bolbitis and Buce, after that it attacks older parts of more established plants in particular the old stems of the Nympaes floaters once they have stoped growing. 🙂

Al plants grow very good, steady and need regular trimming.. I dose with a mix of Profito and tropica PG for extra macro's. The Mini bolbitis doesn't care, if i put it in old leaves turn black and melt away.. After weeks it shows new growth, very tiny leaves. And i indeed found staghorn on some of them. A spot triet with h2o2 does a perfect job to get them clean again. I'm afraid i'm exaggerating when i say they grow maybe 2 millimeters a month.. 🙂 But they grow.

I noticed it's roots grow faster then it's leaves, but actualy i see al epiphytes in my tank do that.

I was more thinking of, it's soft water it doesn't like.. Got another smaller tank, only planted, gets higher dosage, same story mini bolbitis melts old leaves.