Nitrate increase oxidative stress

[BeanAnimal]

Maybe poor choice of word but you're totally missing my point by worrying about semantics. The study concludes that elevated nitrate only becomes destructive when corals face severe phosphorus starvation under heat, an asset mismatch that a steady input of fish food prevents in a home tank.

I am not missing your point (we’ll get to that in a moment). I was making sure the idea of a “balanced” water column ratio of N and P was not being asserted or promoted. It is a common misconception in this hobby worth correcting. I opted to overlook the other more technical problems with the post. But since you insist that I missed your point, let’s examine it.

You responded by telling me what the study “concludes,” but it does not say nitrate is harmful only under heat stress and severe phosphate starvation. Nitrate enrichment occurred before heat was applied and also showed adverse effects. Heat made the response worse.

“Fish food makes nitrate and phosphate rise and fall proportionally.” By what measure? They are consumed and exported through different processes, at different rates. Feeding does not guarantee that either remains in the water column, let alone that their readings rise and fall proportionally. A well fed tank can still be phosphate limited.

Mature live rock may very well have helped your tanks, and the organisms it brings can be beneficial. But “more biodiversity” is too abstract and is often presented with no real definition.. More of what, and how did you determine it helped? Why is more better? The absence of nuisance algae does not answer either question. We don't have a definition of biodiversity or better here. Just something to think about when promoting the idea the more "biodiversity" is better.

And lastly: You indicated
“Dosing ammonium or urea risks toxic free ammonia.”
As with any dosing, proper care is needed. Randy addresses this in his ammonia dosing article. Dosing too much of anything can pose acute risks.

 

[ereeef]

I am not missing your point (we’ll get to that in a moment). I was making sure the idea of a “balanced” water column ratio of N and P was not being asserted or promoted. It is a common misconception in this hobby worth correcting. I opted to overlook the other more technical problems with the post. But since you insist that I missed your point, let’s examine it.

You responded by telling me what the study “concludes,” but it does not say nitrate is harmful only under heat stress and severe phosphate starvation. Nitrate enrichment occurred before heat was applied and also showed adverse effects. Heat made the response worse.

“Fish food makes nitrate and phosphate rise and fall proportionally.” By what measure? They are consumed and exported through different processes, at different rates. Feeding does not guarantee that either remains in the water column, let alone that their readings rise and fall proportionally. A well fed tank can still be phosphate limited.

Mature live rock may very well have helped your tanks, and the organisms it brings can be beneficial. But “more biodiversity” is too abstract and is often presented with no real definition.. More of what, and how did you determine it helped? Why is more better? The absence of nuisance algae does not answer either question. We don't have a definition of biodiversity or better here. Just something to think about when promoting the idea the more "biodiversity" is better.

And lastly: You indicated
“Dosing ammonium or urea risks toxic free ammonia.”
As with any dosing, proper care is needed. Randy addresses this in his ammonia dosing article. Dosing too much of anything can pose acute risks.

I completely agree that N and P export rates differ and that raw dosing requires proper care. My point is simply that a mature, high-input home system handles nutrient availability very differently than a controlled lab environment where elements are strictly isolated under thermal stress.

To be clear im not asserting or promoting any mathematical ratio in the water column; im simply pointing out that having both nutrients available as a joint input prevents the absolute phosphate starvation that the lab environment intentionally forced. the entire study is explicitly centered around heat stress (simulating ocean warming heatwaves). im not swinging temps in my home system

 

[BeanAnimal]

You’ve narrowed your point, but your remarks thus far don’t align with the study.

They did not “intentionally force” phosphate starvation. The tanks had a continuous flow of natural seawater that contained a measured level of phosphorus. They stopped feeding the corals, but there was still a supply of phosphorus. We don’t know if phosphorus was depleted.

Sure, the study is centered on heat stress, but that is irrelevant to the adverse effects reported during nitrate enrichment before heat was applied. Your tank temperature has nothing to do with what the study measured.

 

[BeanAnimal]

In general it occurs to me that there is another problem with assuming the samples became phosphate limited. The corals responded more favorably to ammonium. If that response meant more growth, it could also have meant greater demand for phosphorus. In that case, why assume phosphate depletion occurred in the nitrate treated system but not the ammonium treated system? Maybe one or the other was limited, both, or neither.

Also, we don’t really know how much phosphorus was available to the corals in either tank. Phosphorus continued to enter with the steady stream of seawater, but did one or both tanks become phosphate limited? The starting N:P ratio does not answer that question, and neither does the fact that feeding stopped. So that looks to be unresolved. They also mentioned the starting ratio as if it established phosphorus sufficiency or uptake. That is an error in my view.

 

[ereeef]

yea not trying to be rude, so help me if i am misunderstanding.

The study explicitly states that the initial physiological changes under nitrate enrichment alone were transient. The corals adjusted to the nitrate at normal temperatures.

"Moderate seawater enrichment with nitrate leads to a transient imbalance in coral’s redox status, while ammonium benefits their energy metabolism."

The paper explicitly states that the severe metabolic destruction and bleaching only happened when the two stressors were combined. Maintaining a stable temperature prevents this breakdown catalyst.

"Nitrate enrichment under thermal stress significantly decreases coral's aerobic scope and increases oxidative stress condition and bleaching response compared to a low-nitrogen condition"

The 'continuous flow of natural seawater' used was Mediterranean surface water, which is notoriously ultra-oligotrophic. Its baseline inorganic phosphate was under 0.05 µM. By spiking that water with 20 µM of nitrate while adding 0 µM of phosphate, are the researchers not engineering an extreme water-column N:P ratio?

 

[BeanAnimal]

My narrow point was that nitrate had measurable adverse effects before heat, contrary to your earlier claim that it was harmful only under heat and severe phosphate starvation. I made no distinction of severity one way or the other.

More importantly, where did you get 20 µM nitrate and less than 0.05 µM phosphate? This study reports 3 µM nitrate enrichment and about 0.2 µM phosphorus in the incoming seawater. Your proposed extreme N:P ratio is not the experiment described in the paper.

Nonetheless, the incoming water's N:P ratio can't tell us whether the corals were phosphate limited. If phosphate limitation is proposed as the cause of the nitrate response, then phosphate availability needed to be measured during the tests.

The paper reports phosphorus in the incoming seawater. In tank monitoring only measured nitrate and ammonium. That means phosphate starvation is a possible explanation that could be tested but wasn’t and can’t be concluded from the starting ratio. We can't know in any tank whether it was depleted or not.

 

[ereeef]

My narrow point was that nitrate had measurable adverse effects before heat, contrary to your earlier claim that it was harmful only under heat and severe phosphate starvation. I made no distinction of severity one way or the other.

More importantly, where did you get 20 µM nitrate and less than 0.05 µM phosphate? This study reports 3 µM nitrate enrichment and about 0.2 µM phosphorus in the incoming seawater. Your proposed extreme N:P ratio is not the experiment described in the paper.

Nonetheless, the incoming water's N:P ratio can't tell us whether the corals were phosphate limited. If phosphate limitation is proposed as the cause of the nitrate response, then phosphate availability needed to be measured during the tests.

The paper reports phosphorus in the incoming seawater. In tank monitoring only measured nitrate and ammonium. That means phosphate starvation is a possible explanation that could be tested but wasn’t and can’t be concluded from the starting ratio. We can't know in any tank whether it was depleted or not.

Oh that’s my fault I totally misread those numbers not sure where that came from. I’m seeing the parameters were a lot less extreme than I thought

 

[ereeef]

My narrow point was that nitrate had measurable adverse effects before heat, contrary to your earlier claim that it was harmful only under heat and severe phosphate starvation. I made no distinction of severity one way or the other.

More importantly, where did you get 20 µM nitrate and less than 0.05 µM phosphate? This study reports 3 µM nitrate enrichment and about 0.2 µM phosphorus in the incoming seawater. Your proposed extreme N:P ratio is not the experiment described in the paper.

Nonetheless, the incoming water's N:P ratio can't tell us whether the corals were phosphate limited. If phosphate limitation is proposed as the cause of the nitrate response, then phosphate availability needed to be measured during the tests.

The paper reports phosphorus in the incoming seawater. In tank monitoring only measured nitrate and ammonium. That means phosphate starvation is a possible explanation that could be tested but wasn’t and can’t be concluded from the starting ratio. We can't know in any tank whether it was depleted or not.

Oh that’s my fault I totally misread those numbers not sure where that came from. I’m seeing the parameters were a lot less extreme than I thought

I guess I was trying to say that high nitrates are not an automatic death sentence for a home aquarium. Sorry about that!

 

[BeanAnimal]

I guess I was trying to say that high nitrates are not an automatic death sentence for a home aquarium. Sorry about that!

That is a reasonable position that I would not argue against.

To be sure, I also feel that feeding is a better way to import N and P as opposed to dosing it directly. My point above was simply about not relying on ratios.

Happy Reefing!