Nitrogen/Phosphorus ratio

[ksed]

Do we know the nitrogen/phosphorus ratio uptake in bacteria when we carbon dose?
Eg we know caulerpa is approximately 20:1

 

[Randy Holmes-Farley]

We do and we don't.

The big problem that greatly messes with the ratio is the amount of denitrification driven when we carbon dose, which greatly increases the consumption of nitrate even if the N : P ratio is staying the same in the bacterial tissue.

That said, actual aerobic bacteria do not seem a lot different than macroalgae or other organisms ion the rough amount of N and P present in tissues. This paper analyzes many marine bacterioplankton

http://aem.asm.org/content/68/6/2965.full

"The N : P ratios of the bacteria varied between 5.5 and 19 (average of individual isolates), which is within the range of what has been reported for natural systems" [note these are weight ratios ]

"The N : P ratio increased when the cells became C limited, which indicates that the relative amounts of N are less affected by C limitation than the amounts of P."

"Since bacteria can store P as polyphosphate (32), one can expect lower C : P and N : P ratios when elements other than P are limiting the growth and P is in excess, which was also the case in our experiments. "

 

[ksed]

Interesting that they are similar to macro algae.

So when we carbon dose are we primarily feeding anaerobic bacteria? Not aerobic ?

Thanks

Randy

 

[Randy Holmes-Farley]

Interesting that they are similar to macro algae.

So when we carbon dose are we primarily feeding anaerobic bacteria? Not aerobic ?

Thanks

Randy

Both. While I doubt most people have any idea what the relative proportions of the two are, the fact the organic carbon dosing often drops N relative to P by substantially more than this ratio suggests that the denitrifying component is significant.

 

[ksed]

Interesting

Thanks Randy

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing. :)

 

[ksed]

Do we know if our aquariums are carbon limited? Or is there anyway to find out if we are limited.
I have heard that we are limited compared to a natural reef.
I also heard carbon accumulates in our tanks through feeding and if running a calcium reactor you will be adding more carbon. The question I have is this carbon suitable for bacterial growth?

 

[Randy Holmes-Farley]

Limited must be applied in the context of some specific process.

It might be nitrogen limited for one algae, phosphate limited for another, and organic carbon limited for some type of bacteria (or any other such combination).

The fact that adding organic carbon reduces nitrate means that in some ways, denitrification is organic limited in many tanks.

The fact that adding bacteria like MB7 has an effect may also mean it is bacteria limited in some cases.

A CaCO3/CO2 does not add any organic carbon. It adds CO2, but any tank at the same pH and alkalinity has the same available CO2.

I do not know if anything we usually want to keep in reefs is CO2 limited, since many marine organisms use bicarbonate rather than CO2 as the source, but some algae may be and those will thrive as the pH is lowered. I discuss those here:

Photosynthesis and the Reef Aquarium, Part I: Carbon Sources by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2006-10/rhf/index.php

 

[ksed]

Thanks Randy!

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing. :)