Re: Nitrogen

Stephen.Pushak wrote:
>all this talk about CO2 and O2 and N2 in solution. Here's a new
>question: do fishes contribute to the nitrogen compounds in
>solution (ammonia, nitrates etc.) by consuming gaseous nitrogen
>and converting it somehow? We know that under certain circumstances
>bacteria will convert nitrogen compounds back to gaseous nitrogen
>which would result in a net loss of nitrogen in the system (ignoring
>additions of fertilizers, food and new aquatic creatures)

Nope, you and I and the fish in our aquariums are unable to fix nitrogen to
form proteins. We have to get our proteins from our food so if the N is not
already bound up in an amino acid it won't do us any good. Some bacteria,
I'm sure you're familar with nitrogen fixing bacteria on legume roots, have
the capability of converting N2 into compounds usable by plants.

To my knowledge there are no higher level organisms that can fix N2. I'm
not however sure about whether intestinal bacteria in some herbivores can
fix N2. A cow eats grass to feed cellulose digesting organisms in it's gut,
which are in turn consumed by the cow. Perhaps a biologist can help here,
it is my understanding that the bacteria in the cow's stomach convert the
cellulose to sugars but get protein forming nitrogen in the protein from
the grass.