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How biomass and light level affect CO2 uptake.

Discussion in 'Articles' started by spider72, Feb 2, 2010.

  1. spider72

    spider72 Lifetime Charter Member
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    There is an article about water hyacinth disapperance from Victoria Lake http://freespace.virgin.net/ae.williams/New/2005%20Aquatic%20Botany%20-%2081%20-%20300-314%20Water%20hyacinth%20(Eichhornia%20crassipes)%20in%20Lake%20Victoria%20-%20why%20did%20it%20vanish%20so%20quickly%20and%20will%20it%20return%20.pdf
    CO2 uptake tests have been carried out, and two graphs (fig.2 and fig.3) clearly showing the relation between ligth intensity and biomass and CO2 uptake rate.
    Obvious for most, but not for all aquarists.
    So when biomass is increasing after tank is started and plants are taking over, check CO2 levels frequently and increase dosing.
    The same if you have increased light level and sometime photoperiod length.

    As fig.3 is sugesting, CO2 uptake level is almost linear (proportional) in relation to biomass growth.
     
    #1 spider72, Feb 2, 2010
    Last edited by a moderator: Feb 2, 2010
  2. Tom Barr

    Tom Barr Founder
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    I agree with the paper about this aspect.

    In aquariums, we can have a few different things going on, much like the graphs in that paper.
    However, we can also have the plants still define and adapt the environment to their suiting.

    How?

    Once well established, wetland plants pump a lot of O2 into the sediment, this in turn pumps alot of O2 to the bacteria, which respire like we do and give off a lot of CO2.
    So good root systems play a large role.

    I'm a bit worried that we might be tempted to draw more from the paper about CO2 and plant biomass than we can really say. Hyacinth is a strange plant and is not submersed, it needs very high light to drive growth this fast also.
    The curves look similar for submersed aquatics, See Van, Haller Bowes, 1976 for an example.

    Still, it's common sense to expect a relationship to increase as light, CO2 and biomass increase as well as the reverse.

    Regards,
    Tom Barr
     
  3. spider72

    spider72 Lifetime Charter Member
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    My intention only was to show the relation. Of course condition which has been applied durring test in the paper are quite far from tank conditions or probably eaven natural submersed systems, both light and CO2 available to the plant.
    But I was suspecting, that relations for tank could be similar, just range of values lower - probably much lower.
     
  4. Tom Barr

    Tom Barr Founder
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    Sure, there's some relationship, I, and most folks would predict more CO2/nutrients etc are needed for more biomass.
    Likewise, more CO2 will be needed with more light intnesity.

    I think a better paper would be Troels, Ole and Chiristian's apper on the Biology of aquatic plants off Tropica's web site.
    That's very speciefic to our situation and has appropriate intensities and CO2 ranges that appliy specifically to hobbyist.

    They used a table of increasing light and CO2 to make a comparative table of growth rates.
    Give it a good read, it's one of the better applied papers on how light and CO2 interact with aquarium plants.


    Regards,
    Tom Barr
     
  5. spider72

    spider72 Lifetime Charter Member
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    If you mean this one writen in 4 parts, than I know this paper quite good. It is one of my classic reads and I am refering quite often to this paper on polish forums as it has been translated to polish some time ago.
     
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