Re: Allelopathic Barley

[AquaServe at aol_com]

<<<Could this be because its efficacy hasn't been positively established in 
the
_larger_ bodies yet?

Very possible.  The reason I raised the question at all is that I have heard 
from several people in other conversations, web discussions, etc., that they 
use barley straw in their ornamental ponds quite regularly...if all the sites 
selling the stuff is any indication of it's popularity, it is quite standard. 
 So, it seems logical to me to ask the question if it would work in an 
aquarium...it works at all.

<<<Does this model include the necessary "activation period" for the straw?
Does it also account for the need to keep the water essentially _unchanged_
throughout the testing period? After all, we're not only emulating ponds
(and not streams), but for all intents and purposes using it as a
replacement for "allelopathic" compounds - how would a regimen of water
changes allow for sufficient concentration?

Absolutely it includes the needed activation period (under specific 
temperature requirements...generally two weeks).  As to water changes, yes, 
it also includes that...they are not performed during the testing period.  As 
a side note, the testing model includes more than one aquarium...need a 
control tank of course.  It includes 5 tanks actually.

<<<Outside of the inability of, say, Purdue University (
http://www.sfapms.org/Articles/barleypub.pdf ) or Ohio State University (
http://ohioline.osu.edu/a-fact/0012.html ), among others (North Carolina and
Florida State), to provide *positive* results, the majority of "studies" and
sites attribute the effect to "the release of _some chemical_". Hmm...sounds
quite a bit like most of the sites on aquatic allelopathy, come to think of
it.


This statement is true.  I also question studies that explain away any 
possible mechanism as "the release of some chemical".  I also wonder why the 
studies in the US were not as nearly successful as in England.  However, this 
is neither here nor there...seems to me that it would be easier to study in a 
smaller controlled aquarium than some large outdoor pond anyway.  Besides, if 
it does not work in an aquarium (the reason for the study in the first place) 
then there's the answer.  I am not hell bent on seeing any test end in a 
positive result just to make a point...I am actually curious if the idea has 
any merit.


<<<"When straw rots, chemicals in the cell walls decompose at different rates.
Lignins are very persistent and are likely to remain and be released into
the water as the other components decay. If there is plenty of oxygen
available in the water, lignins can be oxidised to humic acids and other
humic substances. These humic substances occur naturally in many waters and
it has been shown that, when sunlight shines onto water which contains
dissolved oxygen, in the presence of humic substances, hydrogen peroxide is
formed." ( http://www.exit109.com/~gosta/pondstrw.sht - which is one of the
English sites, by the way)

So don't forget that _high DO levels and sunlight_ would be essential parts
of the study as well. Wouldn't *that* be a tricky balance, even in a large
tank?


This is actually the study that caught my attention. I find it the most 
detailed.   As for the balancing act, I don't see it as difficult at all.  
Sunlight...well the UV sunlight is what is needed (supposedly)  but again, if 
conditions in the average aquarium (what ever that would be) are not correct 
for this process to work (again...if it does in the first place) then the 
study would prove useful in that ...hey, it doesn't work in your avg. 
aquarium and hence would be worth the money.  


Anyway, I don't mean to sound like I am somehow trying to defend a study that 
has never been done or prove a theory that I have no direct connection to.  I 
am just curious and was hoping others would be as well.  I'm still going to 
give it a try and write my article :)

Duane