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Ole's refute to allelopathy having any significant effect on algae in aquariums

Discussion in 'Articles' started by Tom Barr, Oct 17, 2006.

  1. Tom Barr

    Tom Barr Founder
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    http://www.bio-web.dk/op/pdf/TAG_2002_15_7.pdf

    I have long rejected this hypothesis that allelopathy plays a significant role in aquariums in regards to plants and algae.

    Many seem to still think it's likely.
    But few experts will say that it is, I've proposed numerous experiments one might do to show this for themselves.

    The above article was in TAG several years ago and we(mostly myself) pretty much beat the idea into the ground.

    Ole will be at this years' AGA event BTW.
    I have some questions for him too:)

    Regards,
    Tom Barr
     
  2. Professor Myers

    Professor Myers Guru Class Expert

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    Closed System Environments & Allelopathy

    I'll grant it some possibilities, but I'd expect nutrient potential to become a more likely factor ! By the time Allelopathy comes into play aren't you already leading with your chin ? ;) In laymens terms don't we already have enough sound reasoning to Water Change the Bloody Tank ??? LOL. :p If Allelopathy were to become a dominant factor in aquariums You're just not paying attention...
     
  3. Tom Barr

    Tom Barr Founder
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    What about a non CO2 plant tank though?
    E.g. no water changes for months/years?

    You can still remove the chemicals with Activated carbon in such tanks also :idea:

    By default, the non CO2 approach does not test the water parameters seldom if ever. That's part of the allure and simplicity.

    What I did some years ago, was this:

    Observation: some plants did poor in the the non CO2 tank. Some did well.
    Over time things ebbed and flowed, some plants wasted, some flourished.

    I removed the soil and dosed just inorganic ferts with plain sand/flourite.
    I found that fish food left you a deficit of K+, Ca, Mg, SO4(likely), often times NO3 and PO4. Traces are often added to non CO2 tanks so those where not tested nor would doing so reveal any new insight due to testing issues for Fe.

    Fish waste added a fair amount of N and P, but often once the plants grew in, these where very low and consumed rapidly by hungery plants.

    Adding KNO3 and KH2PO4 enhanced growth.

    Not all aquarist have the same fish loads either.
    Adding trhe GH booster really helped things, once a week of these was enough to allow you to grow most plants, up from 50 species to about 200 with these routines.

    With the test kits, I found a fairly robust range that was about 7-12 x slower than the CO2 enriched 3-4w/gal tanks.

    Most of the problems folks assoicate with plants in non CO2 tanks are not allelopathic, rather, limitation based.

    You can be an arm chair philosopher and speculate till the cows come home, offer research support etc, but unless you test and see if something works or not, you will not gain much new insight.

    From such test and questions, we learn a lot more than from speculation.
    We often specyulate to hopefully answer the question/s in the future and have some one new come along and advance what is known about a subject.

    Raising good questions is also a great idea.
    She certainly did this more than any other IMO.

    Regards,
    Tom Barr
     
  4. Professor Myers

    Professor Myers Guru Class Expert

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    Non Co2 systems

    I run 3 main tanks these days. You may be the root cause of this long term experiment ??? At the very least the catalyst !

    1 High Tech (No holds barred, on the lunatic fringe, Heavy on the LUNATIC)
    1 low tech (Yeast reactor Co2 , DIY reactor, Strict EI and maintenance)
    1 No Tech (Classic Dutch: Don't touch it you'll break it ! )

    In the long term this may allow me some reasonable data ? But they all exhist to beg the question

    All other tanks are incidental, or experimental, but those 3 main systems are my litmus test.

    I don't believe there is a perfect method...but There Is something for everyone. Life as I know it seldom recognizes absolutes. This is an inherrent risk of corroborating research.

    One of the greatest strengths of a diverse forum is in it's numbers ! This alone allows us all to test the limits daily. A group of like minded individuals that ask the very same questions without end. While it may appear tedious it is in fact honing, and keening the hobby, and the science. Prof M
     
  5. Tom Barr

    Tom Barr Founder
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    There is no perfect method because each has a trade off, which method best suits the goal of the tank/it's owner etc is the primary focus for myself.

    Regards,
    Tom Barr
     
  6. ofri

    ofri Junior Poster

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    I always felt that competition for resources was not the only reson plants seem to have a bad effect on algae grows.
    I noticed that a "happy plant" won't be attacked by algae even in an aquarium with very few plant. while in the same aquarium, a "sad plant" can be attacked.

    So maybe what I call "happy plant" is a plant strong enough to fight algae with allelopathy.

    That's cool :)
     
  7. Tom Barr

    Tom Barr Founder
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    So define a sad vs a happy plant more specifically.
    What might be the issue there?

    You need to provide similar conditions and acclimating time for the plant comparison also.

    Sad plants often are stunted and take a long time to recover. Sad plants often do not have good growing conditions to begin with for that plant, some plants, say Hydrilla or Milfoil are very strong competitiors.

    In a tank with very few plants, I'll assume such a tank si non CO2, generally a fish tank with some plants added?

    In such cases the sad plant gets beaten out for nutrients.
    Thus the sad plant is beaten out for nutrients.
    Then it's only a substrate for algaer growth like a rock or the glass etc.

    The healthy plant is able to out pace formation of the algae, even Anubias are able to do this.

    Regards,
    Tom Barr
     
  8. ofri

    ofri Junior Poster

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    OK, so maybe it's not allelopathy, but the "out pace formation" (That was one of my theories but I never heard about it until now).

    I just never understood the "competition for resources" theory, because in a high-tech tank there is always enough nutrients but still no algae.

    I hear people advising to plant very dense in a new aquarium, is this at all true?

    How can we distinguish between the two factors - "allelopathy" or "out pacing of formation"?
    Perhaps taking a very big tank, with only one plant and lots of nutrients and CO2 (very low concentration of toxic),
    and compare it with a tank with the same conditions but many plants (of the same kind).
     
  9. Tom Barr

    Tom Barr Founder
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    Well, one is growth rate and light competition, if anything, plants outcompete algae for that resource, CO2, and NH4.

    Not NO3, PO4, Fe etc.
    Plants cannot outcompete the algae effectively for that, periphyton studies have long shown that with respect to PO4 in wetalnds, about 250% lower PO4 levels than submersed macrophytes can withstand.
    And it was a very good studies on tropical conditions and plants.

    Very applicable to this situation.

    also, plants reproduce vegeatively in our case, algae are all sexual, thus they produce spores to respond to different parameters. What germinates a spore to bloom?

    That is different than a stable system where two adult species of plant and alga are present.

    Many try to compare these two together as equals, when this is like comparing aquatic plant seeds and algae spores in competive fashion.:eek:

    It's not the same.


    Regards,
    Tom Barr
     
  10. ofri

    ofri Junior Poster

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    I'm a little lost...
    What is the main reason algae do not thrive in a high-tech tanks (planty of light, co2, nutrients...)?
     
  11. Tom Barr

    Tom Barr Founder
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    There is no one single reason.

    NH4, vegetative vs sexual reproduction, CO2, light differences etc all play roles with specific species of algae.

    NH4 induces algae whereas NO3 does not over a an extremely wide range.
    Too little PO4, NO3, Fe etc can induce algae as well, as can variations in CO2 ppm under higher light.

    So too little nutrients can induce BBA, GSA, GDA, BGA, hair algae.

    Not so much excess.

    Algae have been around a long time, they have little reason to worry about plants outcompeteing them, they will wait till the plants die back and then they will take over in natural systems and many natural system don't have plants anyway, there's not enough nutrients to support them.


    Plants namely grow fast when they have lots of light/CO2 and nutrients.
    Just like in our tanks.

    More plants=> less algae.

    Algae have spores waiting and hanging out till things get good and the environment is ripe for them to grow well.

    Plant seeds and algae spores just don't sprout and germinate for no good reason.

    These are adaptations to get through tough times ahead.
    Most desert plants are annuals and bloom only after a rain.

    Algae, same type of thing, you add NH4, which is a good indicator of good growing conditions, and the algae will take off.

    Some algae like lower nutrient levels before spores germinate, some like it when CO2 is all over, some when PO4 is low etc.

    I'll go into detail later about all that, it's a 2-3 part series on algae I'll write up.

    Regards,
    Tom Barr
     
  12. ofri

    ofri Junior Poster

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    ok, thanks
     
  13. Martin

    Martin Lifetime Charter Member
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    so, did you speak to Ole about alleleopathy then Tom? Troels was there as well, perhaps he had thoughts on the matter?
     
  14. Tom Barr

    Tom Barr Founder
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    We agree on most everything each have said. I've spent the last 3 days with them taking them all over the Bay area and 2 with Karen.

    It's the rest of hobbyists that have disagreements and issues:D

    Regards,

    Tom Barr
     
  15. Tom Barr

    Tom Barr Founder
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    By the way, after speaking with several researchers in aquatic botany, I've been unable to find critical in situ CO2 measurement like the readings I got from the CO2 meter probe.

    No one has really ever done a good study using it in natural systems.

    Seems like they'd want to measure the most typically limiting component of submersed plant growth.

    Give what we know about morphology, flow and CO2 differences in our tanks, a simple issue like differences in CO2 uptake between species would be a strong reason for one of those species not to do well together. Many claim allelopathic reasons. I've never been able to show this even with 300 + species. Some critics have claimed perhaps I just needed higher biomass of one or the other species, but this does not seem like that valid of an argument.

    If it where, typically with allelopathic chemicals, we see a a strong response over a wide range of concentrations of that chemical on the susceptible plants. In otherwords, the concentration is less important.

    Still, some plants are far more aggressive at CO2 uptake than others.
    This can be measured and has been. Given the large role CO2 plays and at limiting levels, this can really have a dramatic effect.

    It seems that this issue, rather than allelopathy, whether it is plant=plant or algae - plant is really the main driver.

    To test this, we can (and many have), manipulated CO2 and have had repeatable and strong responses from plants. Some die etc, most get algae.

    With allelopathy, we can test using ACTIVATED carbon to remove any alleopathic chemicals, again, many have done this and no one has EVER reported a correlation between algae and using activated carbon that I or others are aware of.

    So given the observations and simple test a hobbyist can do and draw from, this entire idea, while perhaps a sexy idea, is pretty weak in it's logic, experimental results, and the research which shows little(no) support to date in any natural system.

    Questions arise about how to tease apart the other causes to poor plant growth, algae blooms etc, these must be addressed and ruled out before being left with some pie in the sky theory.

    Little by little, test by test, year to year, you pick away at the questions and get around to testing it and seeing.

    Somethings might require $$ equipment, some can be explained well using basic hobbyists planted tanks and test.

    Regards,
    Tom Barr
     
  16. Martin

    Martin Lifetime Charter Member
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    I recently attended a lecture on allelopathy by Elisabeth M. Gross the leading researcher on alleleopathy in Europe.
    She's written a paper(one of many) named ' Alleleopathy of Aquatic Autotrophs'

    Very interesting read..

    it can be found in:

    Critical reviews in Plant Sciences 22 (3&4):313-339 (2003)


    or I can scan you a copy from work, if you haven't got access to the paper.
     
  17. Tom Barr

    Tom Barr Founder
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    Hi,
    I think I read it.
    I'm sure Ole has as well.

    Regards,
    Tom Barr
     
  18. MarmoteX

    MarmoteX Junior Poster

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    A limiting factor is not only the one that is on a low concentration, but can be the one in a high concentration.

    Competition between algae and plants is not exactly the type of competition there is between species on the same niche. So I guess there wouldn`t be a total "displacement" of algae. For example potassium is an inhibitor in some algae reproduction (i don´t remember where i read it).

    Mr Barr have you done experiments on algae and high concentrations of nutrients?. Like the one you did for plants for the EI. It would be interesting to see how concentration gradient of any nutrient plays roll on algae development.
     
  19. colinsk

    colinsk Junior Poster

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    Tom, Did you ever write this up? I would be very interested to read it.
     
  20. infopimp

    infopimp Junior Poster

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    I also was wondering if the 2-3 part series on Algae ever made it out. No pressure, Tom!

    :)

    -steve
     

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