Plants and Algae

[Allen_1971]

In a previous post by KF, the topic on phosphorus and roots diverted to the discussion of plants and algae. As requested, a seperate thread has been started to accomodate the discussion.

[Allen_1971]

OK to start the ball rolling...

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From the thread phosphurus and roots, BCLee wrote On 12/18/2002 5:46:10 PM

To my knowledge, both algae and plant have the same access to the nutrients in the water. The algae do not wait until the plants finish "eating"; and feed on the remaining "scraps";. This just simply don't sound logical to me.

On the other hand... many time we see algae outbreak in a nutrient limited tank... algae being adaptable, tends to have the edge over plants in nutrient limited water... well as far as I know at least. Algae are much smaller in mass and need less nutrients compared to plants... therefore plants will suffer before algae do.

So what stop the aglae from thriving...? In my observation, most of the time, algae attaches itself to plants that are unhealthy. You seldom see algae growing on a healthy leaf. I believe healthy plants/leaves must have some mechanism fighting the algae off. I have not really seen a tank with both algae and plants thriving together... it is usually one or the other.
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Agreed BC, my analog was a pretty poor one, as mentioned in my reply to geoffrey

You bring out a good point on the size of algae and the critical concentrations required for nutrients as compared to plants... and this point does poke great big holes in my theory about plants outcompeting algae for nutrients.

So how do plants fight off algae? Do we boil it all down to alleopathy against algae?

[Allen_1971]

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Geoffrey in another thread wrote On 12/18/2002 6:02:15 PM

But let us have a healthy argument here, if you don't mind, maybe both of us could piece the puzzle together. You said, "A healthy plant should get the lions share of whatever nutrients are out there. Thus out-competing the algae for nutrients, and depriving them." I have to speak against that statement. Recalled my NO3 was zero? My plants suffered, not those pesky BBA. That's show that algae don't need much to survive. And you know that they will live on scraps.
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Thats another good point. Now I can't remember this well, but I remember that certain forms of algae are able to synthesize the N they need... There was a study done which showed specifically that the levels of N and P in your tank strongly bias your tank towards certain forms of algae. They also showed that for N limited tanks, a certain algae (can't remember if it was BBA) would thrive due to its ability to get N (through some means which I forget).

Will do a search to try and find the article.

[budak]

From what I read in the Baensch Atlas, the different groups of algae – BGA, brown (diatoms), red, green etc – thrive under different conditions. In my previous setup, I did not have base fert so used Jobe sticks to feed my rooted plants and inevitably, bits and pieces ended up in the water column, which I believe fed the BBA. I initially added hornwort to control the BBA (as per Baensch) which succeeded in clearing all traces for a few months. But it then came back with a vengeance, depsite the presence of hornwort and reduced use of TMG. Fishload and feeding is moderate, but I did feed frozen bloodworms about twice weekly. The 3 ft tank used a Eheim 2224 with somewhat reduced flow and 144 worth of PL light. temperature was 30-32C. KH 3-4, pH 6.5. CO2 two BPS.

Now after tearing the old setup down, adding base fert and a fan to bring the temp to 26-27C, and with a different fert regime (upping to 3-4 bps of CO2, 5 drops of Mallick's Lushgrow Aqua weekly and 30 ppm of KSO4), BBA has thankfully not reappeared. However, what the Baensch and Dupla references identify as filamentous/thread green algae has appeared on the mosses. It's no comfort that the books say they are a sign of good water conditions and suggest removal by hand or with a stick. My SAE is fat and lazy, and the yamatoes are on strike, so the only option is to laboriously pull the threads up. Is this the price to pay for having no BBA? What could be done then since this kind of algae are said to closest to higher plants in their requirements?

[Allen_1971]

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Vinz in another thread wrote On 12/18/2002 7:55:06 PM

1. Algae is better at grabbing nutrients from the water then plants. Given that you have healthy plants and minimal algae, notice that they usually grow in areas of your tank where the water flow is high? Like at, and near, the filter outlets. There are posts on APD and other forums whereby algae growth were noticeably reduced when the flow is reduced? Plants also have a hard time grabbing nutrients from fast flowing water (Explanation found in Diana Walstad's book).

2. Now we (mostly) agree that algae usually attack unhealthy parts of plants first. When plants are nutrient limited, it means they are not getting all they need to grow and thus is unhealthy. If alleopathy is the reason why a tank full of healthy plants seldom have major algae problems, then I would guess that a plant that is light or nutrient-limited will use the limited energy produced to find better source of the limiting factor (i.e. growing more roots, either mid stem or deeper in the substrate, or reaching for the sky). Chemicals to inhibit algae will be a secondary function.

3. Certain carpet plants are frequent victims of BBA, etc. Most likely, these plants are in conditions less ideal for healthy growth. Either the temp is too high (glosso), not enough lights, possibly they're too short/small (glosso, high grass) to reach the base fertiliser. Thus, they are unable to fight with alleopathy, plus the nutrients in the area are available in excess to algae. Carpet plants that often do not have a problem usually (a) have longer roots or (b) mid stem roots.
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Vinz,

do you have a link to some webby with info on the nutrient uptake capabilities of algae? would love to read... or are you quoting your first point from d.walstad... in which case, which page?

Also, are you inferring that the primary battle against algae is due to the alleochemicals secreted? Or do you perceive other factors involved in the plant vs algae battle?

[Allen_1971]

Just to correct myself, Its actually BGA which can fix N levels and as such are not constrained by an N limited tank. Heres a link talking about N:P ratios and how they affect algae... its still not to detailed.

N:P Ratio and Algae

[budak]

I think it's like the case with land plants in the Legume family (peas, beans, soya, rain tree, flame of the forest, etc). This family of plants harbour bacteria in their roots which synthesize free nitrogen. So they grow very well in poor soils like on roadsides. Since BGA is a kind of bacteria, they could well do something similar.

[geoffrey]

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On 12/19/2002 10:29:41 AM

However, what the Baensch and Dupla references identify as filamentous/thread green algae has appeared on the mosses. It's no comfort that the books say they are a sign of good water conditions and suggest removal by hand or with a stick. My SAE is fat and lazy, and the yamatoes are on strike, so the only option is to laboriously pull the threads up. Is this the price to pay for having no BBA? What could be done then since this kind of algae are said to closest to higher plants in their requirements?


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Budak: I was in the same predicament too. Initially, I had BBA for a short while, that was resolved by upping my low NO3 level. Afterwhich green thread algae took over its place instead. Subsequently, I thought, hey maybe too much NO3 now, so I lower my daily dose and now those pesky BBA algae too over again!

Now my tank has an assortment of green thread, BBA and spot on wall! Kind of like Teo's farm but can only sell algae lah. Right now I am resuming 5ppm of NO3 daily, 20ppm of K weekly, ~1ppm of Mg weekly and 1 drop Dr M's Micro and A1 daily. Intend to bring my plants back to healthy state and hopefully the hypothsis of healthy plants, minimum algae stands.

BTW, KF I have this strong feeling that those Hornwort you gave me are siphoning the NO3. Confirmed not Frogbit because I removed loads of it. Removed all Hornwort yesterday and shall monitor.

[geoffrey]

I have a couple of arguments to support the hypothesis that healthy plants, minimum algae. Could it be possible that healthy plants has better cell wall that protects them from being attached to parasitic algae? Maybe CY Yeo could enlighten, sorry I have to mention you, your replies in KF's thread give me an indication of the vast knowledge you have in this field?

The second argument is could it be possible that plants growing so well get prune of regularly and top healthy apex point are replanted that the algae though the are there but do not get a chance to appear fullest.

Possible?

[Allen_1971]

Gee after an hour reading through stuff on the net, it becomes readiliy apparant that even experts can't agree on what we are trying to dicuss... heres an apparent contradiction posted by Tom Barr on BGA and their ability to fix N.

"The BGA that folks, myself included, have postulated thrive in an N limited
environment are not the kind of cyano's that can use atmospheric N2 by
breaking the N2 dimer using nitroansae enzyme. A heterocyst is required for
N2 bond breaking. I looked at about 10 different samples from a variety of
different tanks. All were Oscillatoria which do not use N2 EVER.

The heterocyst are required for this process since the enzyme cannot work in
a aerobic environment like that's in a cell with a chloroplast cranking out
all sorts of O2. The heterocyst are very distinct and easy to spot. I have
not found one after looking for many hours in any samples. This genus also
does produce heterocyst...

So if you think low NO3 levels causes BGA, well I'm afraid you are likely to
very mistaken. They need it just like the plants."

[CK Yeo]

The current wisdom in plant tank nutrient management (not control or limitation) is that NO3 and PO4 does not cause algae IF CO2 is in equal abundance (I use the word too often). (Some algae use bicarbonates instead of free CO2)
Plant mass will also have to be majority in the tank (can't remember how many %, 70%?). Alleopathy effects algae also... but I suspect that only happens when the plant is growing healthily have extra energy to divert to production of alleophatic chemicals.
Also, it seems that algae need a extremely stable environment for it to grow. Have you noticed that usually only one type of algae dominate the tank? By having lots of plants and proper amount of NO3 and PO4, the nutrient level in the tank cycles through abundance to very low in a few days. Plant grow fantastic, algae cannot handle the volatile nutrient conditions. Healthy growing plants produce alleopathic chemicals when possible.
However, when a excess nutrient exist in relation to NO3, say PO4, plants cannot use it.... Algae which can, therefore grow like crazy. Of course, this again is in relation with other environmental factors like light and CO2, not so simple....

ck
p.s. It is difficult to pinpoint what causes a specific type of algae. But why do you want to know that? As long as you keep to certain well accepted guidelines, we know that algae WILL NOT go out of control.[]

[geoffrey]

No, no, no. NO3 do not cause BGA. BGA cause zero NO3. Vinz and I share the same view about this and have spoken about it in one thread before. Vinz, I no good with this, could you help point Allen to that thread please.

[geoffrey]

Ooh! sorry Allen. Your are right. Didn't read properly.

[geoffrey]

CK Yeo: I see the light! So having healthy plants alone not enough. Must make sure after their uptake no extra goes to algae. Correct?

[Allen_1971]

Heres a statement made by Karen Randell

"If you go back to the Davis and Brinson article, there's an article that
shows (again, for natural conditions) that under oligotrophic and
mesotrophic conditions - low to moderate production rates, generally with
low dissolved nutrient concentrations - that plants compete very well with
algae. Algae do better under eutrophic and hypereutrophic conditions
where total production rates are higher and dissolved nutrients are
generally higher. I can think of several specific mechanisms for that and
some might actually be relevant to aquariums."

so obviously most of our aquariums belong to the eutropic and hypereutropic condition as nutrient levels in our tanks are generally sky high as compared to levels in nature.

I can think of 3 factors then that help with our battle against algae...

1) One is that algae in our tanks tend to have natural predators... Otos, SAE, Yamato Shrimp are just some common examples... and as such, while Algae may thrive, it is consumed at an equally fast if not faster rate. Perhaps where the equilibrium breaks down is when we get an algae bloom?

2) While nutrients are always readily available to plants, our nutrients are deposited in 2 places. The water column and the substrate. Obviously the nutrients in the substrate are made unavailable to the algae. As such while the plants can be seen to be placed in a nutrient rich environment, the algae could actually be limited of certain nutrients, and thus not perform as well.

3) In the sear-collins paper, they find that plants are able to outcompete algae for phosphates at low levels. This is probably the basis for the rule of thumb which advocate maintaining low phosphate levels. Again this could be because plants have access to the phosphates in the substrate while algae doesn not.

[Allen_1971]

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On 12/19/2002 11:58:27 AM

CK Yeo: I see the light! So having healthy plants alone not enough. Must make sure after their uptake no extra goes to algae. Correct?
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Geoffrey, I don't think that quite what he means... after all this doesn't differ much from my now debunked "plants get the main meal and algae get scraps theory"

I think CK is actually talking about the fluctuations in the nutrient levels forming an unstable environment in which the algae does do well. In addition, given that plants have an abundance of nutrients, then they can divert sufficient resources to alleochemical to suppress other plant growth.

CK,

my only quipe about your view is that most of our tanks have more than amble nutrient levels of all macro and micro nutrients. As such, even if fluctuation occur, why shouldn't the algae be able to grow well? Do you have some information which I can read up on this?

[geoffrey]

Er...jammed! Guess that make sense. Hopefully this issue does not come up in Pete's place when we collect our books, may have to sleep over to sort it out. Hey Vinz, how's the situation now? B4 or aft X'mas, what u think?

[CK Yeo]

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I think CK is actually talking about the fluctuations in the nutrient levels forming an unstable environment in which the algae does do well. In addition, given that plants have an abundance of nutrients, then they can divert sufficient resources to alleochemical to suppress other plant growth.
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Correct! But note that alleopathic chemicals do not only suppress algae growth, but growth of other plants as well. I think Ecology of planted aquarium pointed out Val and something... crypt?

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my only quipe about your view is that most of our tanks have more than amble nutrient levels of all macro and micro nutrients. As such, even if fluctuation occur, why shouldn't the algae be able to grow well? Do you have some information which I can read up on this?
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Which is why having lots of plants in tank in the first place is important.
If you take just tank water and put it in the sun, it will probably grow algae.

Published literature talks about natural systems, where plant mass is low. Also, they measure algae growth in terms of chlorophyll... we measure by visual assessment. So it doesn't really apply (does it?).

The herbivour part is raised before, but it doesn't hold cos there are more algae types than what the algae easters we have will eat. Also, unless you intend to stock the whole tank with nothing else but algae eaters. How many times someone on the internet manage to grow something, nothing will eat?

The fluctuation theory is my own hypothesis lah. I dun intend to prove it with any scientific evidence (if that's what you are looking for). The idea is that it is not that algae no grow AT ALL, it is that they dun do as well as the plants, because the environment is not to its liking. So whatever minimium algae growth is taken care of by the herbivours.... sort of like, have you tried growing a certain plant (say R. macandra, or A. madagasxxx) and it just die on you. Why? You will probably say that the conditions are not to its liking although other plants grow like crazy. Same thing apply to algae I suppose.
ck

[Allen_1971]

Eeeks typo errors on my part.... my earlier post should read (note bolding)

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I think CK is actually talking about the fluctuations in the nutrient levels forming an unstable environment in which the algae does not do well.
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CK, I hope you still agree with the above statement.

[Allen_1971]

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On 12/19/2002 12:27:24 PM

Er...jammed! Guess that make sense. Hopefully this issue does not come up in Pete's place when we collect our books, may have to sleep over to sort it out. Hey Vinz, how's the situation now? B4 or aft X'mas, what u think?

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Heheh dun worry... I'm sure 90% of the people will get bored and throw their beer cans at us before we get too longwinded and involved...