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Algae attachin gon plants.....Cutin and CO2 levels, a possible key?

Discussion in 'CO2 Enrichment' started by Tom Barr, Feb 26, 2009.

  1. Tom Barr

    Tom Barr Founder
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    I met Neil Frank today and we did the LFS rounds here in SF. Afterwards at dinner, Neil asked an interesting question that I've thought about for sometime, but did not relate things........connect the dots........ till at dinner.

    The general question was "why does BBA(or any epiphytic alga) attach to weak growing plants?" "Why are some leavesmore suspecptible than others?

    I thought a bit and said that Hydrilla, Egeria and Myriopyhllum lack any significant cuticle, but their growth rates are very fast, so they can outpace BBA and other algae and then form a canopy at the surface, blocking light to algae below and gaining ample CO2.

    But another idea comes to mind.............if we reduce CO2, why are Anubias and other plants attacked so specifically, but other species are not and BBA are not CO2 limited..........Neil asked if there was some plant chemical that they give off to protect themselves(I've not bought into that theory, still don't).

    This gave me another idea.

    When plants are Carbon/CO2 stressed, and cutin is continuously produced by a healthy plant..........eg a plant with plenty fo CO2 available to make cutin, which is a Carbon rich material, they might simply stop making the cutin.

    CO2 is limited, so they focus on getting to the surface, forget these leaves. If there's ample CO2, the plant makes plenty of cutin and it sloughes off the spores that might attach to the plant leaf.

    When CO2 is limiting, they stop making the cutin, it sloughs off leaving only a bare vunerable leaf. It's a bit like a pathogen attacking a stressed plant with thin skin/cuticle vs an unstressed plant with a thick skin/cuticle.

    Since some plants have virtually no cuticle, and they grow fast, can use Bicar etc as a Carbon source, they suffer little from BBA, whereas others, Java fern and Anubias, both grow well emergent and thus REQUIRE a good thick cuticle(same for swords and Crypts). Myrios, Egeria, Hydrilla etc, many fast growing obligate aquatic plants lack a cuticle and it's very rare they ever get BBA.

    Cutin is rich in reduced carbon(wax basically), so it's production and deposition will be greatly reduced if CO2 is limited. No chemical defense needed, plants already have a cuticle layer, but it needs a source of C to make more of it and maintain it.


    Once the leaf is damaged/thinned the cuticle or the plant "decides", it's not worth saving that alga eencrusted leaf, you are not going to clean it up and "save it".
    The plant gives up and just starts growign new leaves instead. So once the CO2 shock hurts the leaf, it's just a matter of time before algae goes after it.

    Might as well trim it off.

    Regards,
    Tom Barr
     
  2. Tom Barr

    Tom Barr Founder
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    A good paper on Aquatic plant stress from Keely.

    http://www.werc.usgs.gov/seki/pdfs/Interactive%20Role%20of%20Stresses%20on%20Structure%20and%20Function%20in%20Aq.pdf

    Note the 2 main figures on stress.

    Another idea is that the thinner cutcle helps the plant with more CO2 gas exchanges, but.........the trade off is that the leaves are now more susecptbile to algae colonization.

    On fast gr4owing weeds, they do not really care much about saving a leaf, longer lived leaves, often do. Also, most the main plants that get BBA, Anubias, Swords, Crypts etc, are emergent most of the year and flooded only for a brief peroid, algae does not bother the leaves for long in such systems. And the algae might serve to protect the plant from high light later in the hot dry season when water is low.

    Regards,
    Tom Barr
     
  3. paludarium

    paludarium Guest

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    Hi Tom,

    I like Keely's article, thanks. And the BBA, hm:rolleyes: , besides leaves it also attaches to rocks, drift woods and especially spray bars, all those materials without cuticles. Hobbyists here applaud your theory for using high and stable CO2 levels in treating and preventing BBA, but some folks still found BBA on the spray bars, and they claimed that BBA loves turbulence. It could be either stable environment/concentration or inhibitory effect of high CO2 levels, or both that retards the development of BBA. But on the spray bars, I have no idea...:confused:

    Regards,
    Erich
     
  4. Tom Barr

    Tom Barr Founder
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    Well, the leaves slough off the cutin, where as wood, rock, glass etc etc, has no sort of secondary protection.

    I was at AquaForest yesterday, most of their tanks where a mess algae wise.
    Full ADA tanks, even well tended, and by ADA's rules etc, have algae issues.

    This was mostly due to too lean and also, mostly CO2. Most tanks has some BBA.
    In tanks where it was more common, they had less flow and little CO2 going in.......

    The 180 looked pretty bad.

    The 120 had some green algae that is comon in esturaies that are highly polluted, very rare in freshwater tanks. Most of the plant sales tanks have more light, and.........more CO2, and , more plant biomass.

    The 90's looked good, they had been redone a few months ago.
    But improvement is flow patterns seem like it would help a lot more.

    I'm not saying BBA does not grow non living things, just why it does not infest plants, or similar algae that attack plant leaves.

    If BBA, other species are covering the wood, spray bars etc, that's easy to kill off, whereas BBA on the plant leaves is ver tough. So a little cleaning goes a long way there,and you still keep the plants algae free.

    My wood is BBA free in my 180 gal.
    I do not clean it though.

    Regards,
    Tom Barr


    Reards,
    Tom Barr
     
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