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[APD] RE: Aquatic-Plants Digest, Vol 6, Issue 30

> > I've argued these mechanisms for some time but I have still felt that 
> > algae
> > "know when to grow" and "when not to grow". I think it might make more
> > sense to folks to consider spores like plant seeds to understand and
> > consider this concept.
> Tom, you are comparing the sophisticated biological function of a very 
> advanced sexually reproducing plant to a primitive algae cell.

Certainly, algae are highly advanced and a product of a very long
evolutionary path well suited to the aquatic environment.
They are the DOMINATE form of plant growth on this planet. While the mode
might be advanced in terms of development, the development of a seed is
based on a terrestiral, NOT an Aquatic existence. There are other non seed
terrestials but I'll ignore those for the moment.

  I'm not 
> sure I buy into the analogy... what scientific evidence exists for this 
> triggering behavior?  I have a copy of Endnote, and access to the major 
> academic journals, please shoot me some references, I'm very interested 
> in this :)

I'm not sure a lot of evidence exist concerning specifically aquatic plants
and algae together.
There's just not a lot of practical applications, grant money etc and this
is a not a large issue since there's little work specifically done on this
issue, but there's more and more work being done on macrophytes role in
shallow lakes.

I think too many folks assume that science has already investiagted
everything. This is simply not true.
Why do you think I am doign what I do?:-)   

> > I'm not sure about some, some algae certainly sense NH4+, I've shown 
> > this
> > with Green water and staghorn, Urea can also be included there.
> I do know of at least two people that use urea based nitrogen sources 
> in their tank and do not have problems with either of these algaes.

Sure at small amounts but if you add more, they will see this.
I've added it as well without issue, but if you add more or add more fish,
the tank will break.

Don't believe me? Try it yourself and stop taking other folk's word for it. 
I use nothing but NH4/urea based ferts for all my non CO2 tanks, fish waste.
If I add too many fish to any tank, it's not the NO3, the PO4, it's the NH4
that sends the tank into algae land.

> > I have been using a pelagic plant, Utricularia stellaris to 
> > investigate the
> > effect of well growing plant on the algae.
> Deliberately using or accidently infected? :)

Have you seen this plant? It's not U. gibba.
It is delibrate.

> Right, but we're making a huge mistake here comparing a lake to our 
> tanks. 

Are we?
That would depend on the lake, a tropical shallow lake full of plants is
much more similar than the previous comparisons of Canadian lakes that
showed PO4 causes algae blooms. 
These tropical shallow well planted lakes don't show this same pattern.
Our tanks also do not show this pattern, adding PO4 does not induce algae
blooms in densely planted tank(PO4 is the variable here, not the other

> Our tanks are artificial and despite all the 'hippie' like 

Bad hippies? :-)

> ramblings our tanks are not ecosystems and I am very suspect of drawing 
> generalizations made about natural bodies of water and extending them 
> to aquarium practice.  

I am as well but some of the same principles can be looked at more closely
in the lab and compared to the field studies.
Then a model can be made and see if it works or not. It's a combinmation of
these 3 elements, not just one.  

The reef hobby was stuck for quite a while until 
> they stopped trying to emulate natural water conditions and started 
> meeting coral needs instead.

They started growing plants to improve water quality.

  I agree we need to give our plants what 
> they need, but the mechanism keeping a lake algae free is unlikely to 
> work in our little glass boxes.  What is needed is well controlled 
> experiments done on an aquarium scale.

What do think I've been doing all this time? I'm not much on arm chair
planted aquarium banter.
It takes time, I'm only one person and have other obligations.
I intend to use tanks to relate things to the field and natural systems.
Along the way, we will get some useful  research about our tanks as well.

> Secondly, and a much more 'philosophical' point, natural systems are 
> exposed to flow of energy and mass and for that reason tend to be 
> highly complicated nonlinear systems (such as the weather).  We must be 
> very careful using "steady-state" (which is the proper term) to 
> describe these systems, as this is not the same as equilibrium.

There are few places that are stable. I study one such place which main
variable is light over the seasonal variation, the other parameters are
exteremely stable so it's like using a gaint natural laboratory. But there
are ways and techiques around these variables and statistical methods to
tease apart data. 
They can be isolated by trying different approaches and test to answer the
question. Often, you simply find out what does NOT work. Then you move on
and try something else. 

.  But there are usually _multiple steady states_ in a 
> non-linear system so even if you replicate the exact ending conditions 
> there is no guarantee you'll reach the same end point... 

That's why we do replicates and more and more of them:) Ugh. It's like
factory work:)
I'm not worried about this issue too much, it might seem like too many
variables from many folk's view, but I know a lot of methods for
investigation. Sometimes you do get stumped. But I am blessed with eternal
hard headedness and go back to the drawing board till I've figured it out. 

There may be 
> an all algae as well as an all plant "solution" to given 
> nutrient/environmental conditions. 

I think there is.

> But there are even more interesting 
> states the lake might be in, limit cycles oscillating from all plants 
> to all algae but happening over a time frame too long for us to 
> observe, especially if there is some essential nutrients that is very 
> limited as has slow kinetics....

Most of these lake systems generally ltake decades to reestablish the
macrophyte populations.
Hurricanes can alters and removed the plants and grass carp etc have also
done damage.
Algae dominated lakes cause a soft floc build up which is bad for bass
reproduction so these issues can relate to fishing here. 
Boaters don't like too many weeds since that will reduce fish as well and
catch their engines(but many use Airboats here) 

> > So perhaps it's NH4 cycling that occurs too fast to measure, but can be
> > traced using isotopes(which is what I'm doing now with a Sag).
> > But out of 319 lakes over  wide range, there's no pattern to suggest 
> > that
> > nutrients cause a lake to be full of plants and gin clear or pea soup 
> > with
> > algae.
> > Planted Aquariums might be able to isolate these issue better.
> Tom, could you please publish some of this data you have/had in TAG?  

Sure, I have posted it a few times recently, Bachmann's, Hoyer, Canifield,
Crismann, Madsen etc
If you want, look at the IFAS web site, they have a search function for all
things plant related.

> You mention experiments you have done in the past about GW, growth etc, 
> Chlorophyll levels, etc... Some quantitative data with a good write up 
> described the design of experiment would be helpful in evaluating the 
> problem a little better and I think the interest level is here.  You 
> have access to some nice lab equipment and could really help us out... 
> "The plural of anecdote is not data" :)

Very true:)
I think there's enough anecdote to kill a whale.

Like many folks that do research, we have a huge backlog of "things to do". 
Right now it's waiting for the centrifuge to finish spinning so I can do my
Cholorophyll samples on the spect for the next two hours. 

Tom Barr 

> Jeff Ludwig
> Elkton, MD

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