Re: [APD] RE: Why algae don't grow and plants do under non limiting conditions

["S. Hieber" <shieber at yahoo_com>]

This is the best hypothesis offered so far. I suppose it is
easily enough related to stagnant ponds and puddles
developing lots of algae and few plants.

Not outcompeted by plants for NH4, but, continuing along on
the teleological track, algae merely resign the contest.
Although it's not clear why algae would decide to resign
when the energy demands are higher. Makes them seem like
darwinian weenies.

sh
--- Thomas Barr <tcbiii at earthlink_net> wrote:
> 
> NH4 needs 8 less electrons to be incorporated into
> Glutamine than NO3.
> This means it takes less energy. That does not mean a lot
> to a large plant
> with plenty of storage space and enzymes already in place
> to the same
> degree it does to small single celled algal spore.
> 
> I'm not sure how far into biochem and genetic inducement
> folks want to go,
> but chemicals such as NO3 and NH4 will elicit different
> responses to the
> genes responsible for Nitrogen metabolism depending on
> their concentration
> ranges. Plants switch and induce NO3 uptake enzymes and
> have both low and
> high affinity enzymes. 
> 
> A high NO3ppm level allows the plant to adapt to this
> higher level.
> Adding high NO3 also allows Cyanobacteria to induce the
> cells to go
> dormant, BGA tends to bloom when the nutrients are very
> low. 
> 
> Once the concentration reaches a certain critical level,
> the gene is
> induced and off the algae spore goes for better or worse.
> 
> At critically low NH4+ levels, that tells the algae
> "someone else" (another
> alga) is growing already and it's a bad time to try and
> make a run at a
> bloom.
> You can see this effect with other algae.
> Some algae seem to reduce or remove other species of
> algae even at non
> limiting levels. Green water and other's seem
> particularly good at this. 
> It also may simply mean that there's very low nutrients
> but we artificially
> add NO3 and having all the plants keeps the NH4 at 0.
> 
> Consider a newly set up tank/a tank with only a few
> plants.......
> The bacteria help stabilize the new tank...........but
> how does this
> prevent algae?
> We know it's not excess nutrients..............
> So what about NH4?
> What do bacteria do? That might help with NH4 => NO3
> 
> If you add the bacteria or a cycled filter, or also add a
> lot of
> plants(over stuff the tank), you also get the same result
> as an established
> tank.
> 
> All just luck?
> Probably not.
> 
> This nutrient is fairly universal, the model fits well
> with algae=algae
> interactions as well as plant algae dynamics, explains
> how the algae spores
> "know" if someone else is there, adding high O2 does not
> show this, so we
> can rule that out. Low O2 or high O2 does not help or
> harm algae. We know
> excess nutrients such as K, PO4, NO3, Fe don't cause
> algae.   
> Adding NH4 does very clearly.
> Adding other observations dealing with tank set up and
> bacteria, the model
> is fairly clear.
>   
> Regards, 
> Tom Barr
> 
> Plant fest is filling up, it will be fun, don't be let at
> home!
> 
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