[APD] RE: NH4 competition

["Thomas Barr" <tcbiii at earthlink_net>]

>> "I think algae are preprogramed to live in specific environments, plants
as
>> well but if they have enough nutrients relative to the lighting, they
will
>> do well if you have enough plants to start off with.
>> I also believe that algae/plants compete fiercly for NH4 produced in the
>> water column.
>> It's a much greater gain for algae to get the NH4 as opposed to NO3.
> Plants also but not nearly as much.
>> When the plants have good conditions, they likely remove all the NH4 as
>> fast as it's produced.
>> When the plants wane due to nutrient deficicencies, this uptake rate
slows
>> down and the algae have a free meal."

> So this would suggest that plants are the top competitor for NH4, followed
> by algae and last of all bacteria. 

Well if the biomasses were all equal, they are not in most tanks, the
plants are in much higher relative biomasses.

In Diana's book she shows comparisons of
> NH4 preference and uptake Vs NO3 in a particular aquatic plant. Do similar
> test results exist for algae uptake or preference? Just how hard is it for
> algae to convert NO3?

Well NO3=> NH4 to glutamine etc is one of the more expensive conversions as
fas as energy goes.
This does not mean as much when you are big like a plant(But still somewhat
significant in _some_ species), but as you become smaller and smaller it
does.
But your requirements for this also become smaller. But there's trade offs
with each niche.

But when NH4 becomes available tio make it worth the algae's while to
bloom, they go to town.
But if you injure/hurt/limit the plants with low NO3, PO4, K, Fe etc, then
the uptake of NH4 is slowed down also.

Like us, it takes a little while for the plants to recover from a
deficicency before they are full force again.

You can play with NH4 using ammonium sulfate, adding progressively more and
more fish/shrimps to a tank till you get blooms etc.

NH4 and NO3 can be labeled using 15N so that you can track who gets what in
a tank.

So you would label the N in NO3 with 5% 15N. Have a tank with algae(pick
your species of interest) and a plant of interest. 

After 24, 48 and 72 hours come back and remove. Scale the relative
biomasses.
Take the samples to the Mass spectrophotometer. Accelerate the 14N/15N and
figure out how much NO3 was taken in by the algae vs the plants.

A similar process can be done with NH4.

I'm more interested in NH4.
I hope to get this dione this spring semester.
Mass specs are fun and cool:)
Fortunately, the test are subsidized so it's cheaper than UC. 
And I have some free 15N. 
Stuff like this makes you more employable. I also am going to do some SEM
work with Green water and some other tiny algae.  

I'll likely use Red Ludwigia and Spirogyra. Not sure yet.

But this would answer who gets what relative to biomass between these two
autotrophes. 

Regards, 
Tom Barr

> Thanks
> Giancarlo Podio
>



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