[APD] Re: NH4+ and NO3- and algae inducement

[Thomas Barr <tcbiii at earthlink_net>]

> Tom, are you suggesting that algae grow much better with ammonium than
> nitrate?

They bloom and start to grow, afterwards they can use either. But NH4+
induces growth of dormant spores in some species that bug us, like GW,
staghorn (Compsopogon) and others. I cannot say for all species of algae,
but a few that you certainly don';t want most certainly do bloom only when
you add enough NH4 to the system. I've added high NO3's(20-75ppm for brief
periods, 1-3weeks) and never had these algae bother any tanks I've set up.
With NH4? A day or two, roughly averaged out to 30 hours when inducement
occurred with GW, and about a day or two later for Staghorn. Urea was not
examined, only NH4. The Staghorn might be more induced by the urea. I have
not looked into that notion.

> This is something I haven't heard before. Don't algae produce
> the nitrate reductase enzyme too?
 
Yes, but to get started in a good environment, much like plant seeds when
they "sense" warm weather/water etc, the algal spore/gametes sense the NH4
at high enough levels to grow well.

Once they start, they can use the NO3 reductase=> NH4=> glutamine etc
But just NO3 alone at relative moderate to low levels does not induce these
same species of algae generally.

> I certainly understand the argument about how stopping fertilization
> increases nitrogen levels in the tank.

? You lost me. If you don't add anything to the tank, how is the N levels
suppose to increase? Which nutrient(s) are you talking about?

> I could understand an argument
> about how a biofilter helps prevent ammonia poisoning in this situation.
> But I don't understand yet why excess nitrate wouldn't cause the same
> algae bloom as excess ammonium.

It's a different ecological indictor of the environment for algae.
It's like a sign that the water column is rich or has enough nutrients right
now for the algae to grow well. NO3 does not do this nearly as much, it
takes more energy to assimilate and generally there's just not much NO3 in
many wetland areas, but after wind/rain runoff etc, often the NH4 levels and
NO3 shoot way up. Algae are adapted to take advantage of this window in
time.
NH4 levels are often high in wetlands in the soil deeper down. If something
disturbs this and it comes up faster than the normal slow rates of
diffusion, then you'll get a bloom etc.

Alage also are very well adapted to water column nutrients and much of the
recycling within many water columns occurs mainly in the form of NH4, it
seldom has a chance for aerobic bacteria to oxidize it to NO3.

Regards, 
Tom Barr

> 
> - Jim
> 

_______________________________________________
Aquatic-Plants mailing list
Aquatic-Plants at actwin_com
http://www.actwin.com/mailman/listinfo.cgi/aquatic-plants