Nitrate- cannot get it to fall

[Hans-Werner]

According to info when I search on his is that this is not correct. On the contrary I found some data that corals may thanks to active channels absorb down to almost zero independent of the intracellular concentration. A mechanism to manage the natural reef ultra low po4. So if this info is correct coral may absorb far lower than 0.02 ppm po4.

Please show your article/evidence! Nothing has come from your side yet.

 

[Hans-Werner]

Ofcourse. As I said, active transport with sodiumchannels to transport PO4. Not all substances need active transport though. CO2 for instance, it diffuse passively through cell membranes. But Ca need a Ca- ATPase to be trasnported (and at same time H ions is expelled). Also the HCO3 needs a trasnport protein to travel into the action site. We know quite much about this as human biologist, so its not so different when coming to cell wall.

Any proof? Any article?

 

[Hans-Werner]

So I have now red partial of the first link(discussion and summary)
Its interesting and have similar message as some other links posted here: Very Low Po4 is bad and If you add a Nitrogen excess to that its even worse for the symbiont membrane stability, so its a similar message.

Its also interesting that the coral increase the P uptake during thermal stress as a way of prevent bleaching. At same time they saw the opposite for N uptake, and debate if its a concequence of zooxanthelle reduction (beginning of bleaching) or deliberately by the coral to prevent bleaching? The first theory is more easy to adapt but the second more beatiful.

I couldnt find anything about that zoo cant assimilate Po4 if below 0.02, but on the contrary , it could increase and adapt the P utake during stress conditions to prevent bleaching. Right?

Obviously only older articles use the tracer method to measure net phosphate uptake or release. Here are two by Sorokin and D'Elia.

In case you don't get the full text of D'Elia here an excerpt

As stated here at natural reactive phosphorus concentrations even a net loss of total phosphorus occurs.

Since both articles state phosphate release in corals it is obvious, also from other articles, that with lower phosphate uptake at lower water concentrations, at some point net phosphate uptake becomes zero or even negative. This is what makes these tracer studies so valuable.