Can Higher Alk help with Coral Browning?

[Lago]

Firstly, I am not facing any issues with browning in my tank at the moment as I am just curious.

Now if burnt tips is caused the lack of production from zooxanthellae paired with excessive skeleton growth. And if browning is due to overproduction of zooxanthellae (I'm guessing that there would be little skeleton growth RELATIVE to zooxanthellae production). Would a possible solution in a high nutrient low alk tank be to raise the alkalinity so the growth of the skeleton compliments the growth of zooxanthellae?

Again I could be wrong in my understanding of this but I'm just curious as to what people have to say. Thanks!

 

[Miami Reef]

Following.

 

[EeyoreIsMySpiritAnimal]

Firstly, I am not facing any issues with browning in my tank at the moment as I am just curious.

Now if burnt tips is caused the lack of production from zooxanthellae paired with excessive skeleton growth. And if browning is due to overproduction of zooxanthellae (I'm guessing that there would be little skeleton growth RELATIVE to zooxanthellae production). Would a possible solution in a high nutrient low alk tank be to raise the alkalinity so the growth of the skeleton compliments the growth of zooxanthellae?

Again I could be wrong in my understanding of this but I'm just curious as to what people have to say. Thanks!

Zooxanthellae growth does not equal flesh growth.

 

[Blopple]

Zooxanthellae growth does not equal flesh growth.

That's his point I think.

The view here is that zooxanthellae production =/= skeleton growth. And that nutrients contribute to, and limit, zooxanthellae production. And that alkalinity contributes to, and limits coral skeleton growth.

He's asking if increasing skeleton growth, and decreasing zooxanthelae production will help to correct coral browning by way of adjusting the water parameters.

It's a cool question, but I don't know enough to answer.

I would guess yea, it would help, but not enough to warrant acutely adjusting water parameters in an established system.

 

[Lago]

That's his point I think.

The view here is that zooxanthellae production =/= skeleton growth. And that nutrients contribute to, and limit, zooxanthellae production. And that alkalinity contributes to, and limits coral skeleton growth.

He's asking if increasing skeleton growth, and decreasing zooxanthelae production will help to correct coral browning by way of adjusting the water parameters.

It's a cool question, but I don't know enough to answer.

I would guess yea, it would help, but not enough to warrant acutely adjusting water parameters in an established system.

Yes thank you, that was the viewpoint I was getting at. Because I was thinking that this could be related as to why lower alks are typically found in lower nutrient systems. Whereas higher nutrients are suggested if one runs a higher alk.

 

[Lago]

Zooxanthellae growth does not equal flesh growth.

I understand this, I'm talking in a scenario where you have zooxanthellae production and skeletal growth as the only variables. With the assumption that the flesh growth is going to keep up with skeletal growth. Thank you for clarifying this point.

 

[gbru316]

I understand this, I'm talking in a scenario where you have zooxanthellae production and skeletal growth as the only variables.

That isn't the case though. And it will never be the case. At a macro level -- in addition to alkalinity (the impact of which is a function of pH), both water flow and light play equally important roles when considering the topic of calcification. And even then, "nutrients" (especially phosphate) are known to inhibit calcification.

Dana Riddle hypothesis that "tip burn" is not a result of lack of zoox. At least, not directly. It's a result of excess photosynthesis byproducts caused by the intense calcification rate. The coral simply cannot remove the waste quickly enough. The followup question would be what can we do to improve waste transfer? For one, maintaining high flow rates will keep the concentration gradient high which assists the coral with removing toxic byproducts. Or, we could slow down calcification, either by reducing light or by reducing alkalinity.


Further -- looking at "nutrients" in the water is a bit reductive. There's this trend to think that measurable nitrate/phosphate = nutrients when that's not quite the case. Mark Van der Wal made a good analogy on Reef Therapy when discussing nutrient levels (paraphrased):

When someone finishes their plate at dinner, we don't assume that they need more food because their plate is empty, do we? No, we understand they're "full" and so long as they get another plate in a reasonable amount of time we're not concerned. Likewise for corals -- just because they've depleted the available nutrients in the water column does not mean they need more. They do store energy for later use within their tissue. So long as we're keeping that reservoir topped up there isn't a problem.

And this is how a natural reef works. There's not an abundance of free nutrients on the reef -- nutrients are closely coupled between producers and consumers. So that plankton that a polyp captured might provide sufficient energy for a period of time.


Regarding browning -- the coral's fat. To avoid it, throw it on a treadmill (increase light) or put it on a diet (reduce available organic energy).

 

[Lago]

That isn't the case though. And it will never be the case. At a macro level -- in addition to alkalinity (the impact of which is a function of pH), both water flow and light play equally important roles when considering the topic of calcification. And even then, "nutrients" (especially phosphate) are known to inhibit calcification.

Dana Riddle hypothesis that "tip burn" is not a result of lack of zoox. At least, not directly. It's a result of excess photosynthesis byproducts caused by the intense calcification rate. The coral simply cannot remove the waste quickly enough. The followup question would be what can we do to improve waste transfer? For one, maintaining high flow rates will keep the concentration gradient high which assists the coral with removing toxic byproducts. Or, we could slow down calcification, either by reducing light or by reducing alkalinity.


Further -- looking at "nutrients" in the water is a bit reductive. There's this trend to think that measurable nitrate/phosphate = nutrients when that's not quite the case. Mark Van der Wal made a good analogy on Reef Therapy when discussing nutrient levels (paraphrased):

When someone finishes their plate at dinner, we don't assume that they need more food because their plate is empty, do we? No, we understand they're "full" and so long as they get another plate in a reasonable amount of time we're not concerned. Likewise for corals -- just because they've depleted the available nutrients in the water column does not mean they need more. They do store energy for later use within their tissue. So long as we're keeping that reservoir topped up there isn't a problem.

And this is how a natural reef works. There's not an abundance of free nutrients on the reef -- nutrients are closely coupled between producers and consumers. So that plankton that a polyp captured might provide sufficient energy for a period of time.

Yes I know that alk, nitrates, and phosphates would never be the only variables. Again I am speaking in a hypothetical sense. To try and see if anyone knows if upping alk would reduce the browning on corals.

Now as for the excess photosynthesis byproduct I'm curious as to why this doesn't happen to the rest of the coral? Because wouldn't the zoox still be cranking out that high level of byproduct no matter the location. Like how does the excess photosynthesis relate to the whitened color on the tips?

As for the dinner plate analogy I kinda agree on that point. Because you have lagoonal reefs which have higher amounts of nitrates and phosphates in comparasion to the typical reefs people speak of. Along with that you have this "dinner plate" that also has parts of "food" by other factors of coastal ecology (I.E. seagrass beds and mangroves which also trap a lot of organics within them.) Also, there are additional cases such as Richard Ross' tank which runs nitrates and phosphates WAY higher than what a natural reef would be exposed to.

Not trying to poke fun at anything you've said I'm just curious as to what causes these things.

 

[gbru316]

Yes I know that alk, nitrates, and phosphates would never be the only variables. Again I am speaking in a hypothetical sense. To try and see if anyone knows if upping alk would reduce the browning on corals.

Sounds like a hypothesis that's ripe for a controlled experiment that is well within reach of the average hobbyist!

Now as for the excess photosynthesis byproduct I'm curious as to why this doesn't happen to the rest of the coral? Because wouldn't the zoox still be cranking out that high level of byproduct no matter the location. Like how does the excess photosynthesis relate to the whitened color on the tips?

I'm no biologist but my hypothesis is that there's less surface area on growing tips so the removal of byproducts is more limited compared to the rest of the coral. I don't really know. I do know that Dana has done a lot of work with test equipment that directly measures chlorophyll content and photosynthesis so I'm inclined to give his opinions a bit more weight than the average hobbyist.

Also, there are additional cases such as Richard Ross' tank which runs nitrates and phosphates WAY higher than what a natural reef would be exposed to.

If there's one thing I've learned over the past 25ish years, it's that there's no right way to "reef." What matters more is adopting a philosophy and sticking to it long-term. The more you mess with things, the lower your chances of success.

Not trying to poke fun at anything you've said I'm just curious as to what causes these things.

I didn't get that impression at at all. I'm just as curious about all this stuff as you are! I just don't see any biological mechanism that relates zoox density to alkalinity. I could very well just be uninformed.

 

[Lago]

Sounds like a hypothesis that's ripe for a controlled experiment that is well within reach of the average hobbyist!

Fair enough I would like to do some of this work once I get my own place and a few additional tanks set up.

I'm no biologist but my hypothesis is that there's less surface area on growing tips so the removal of byproducts is more limited compared to the rest of the coral. I don't really know. I do know that Dana has done a lot of work with test equipment that directly measures chlorophyll content and photosynthesis so I'm inclined to give his opinions a bit more weight than the average hobbyist.

I can see what you mean by that and yes I would say that it would be interesting to see someone conduct such experiments.

If there's one thing I've learned over the past 25ish years, it's that there's no right way to "reef." What matters more is adopting a philosophy and sticking to it long-term. The more you mess with things, the lower your chances of success.

Oh I certainly agree and that's also what I've found so interesting about corals since they're able to tolerate so many varying conditions that we put them through.

I didn't get that impression at at all. I'm just as curious about all this stuff as you are! I just don't see any biological mechanism that relates zoox density to alkalinity. I could very well just be uninformed.

Alright cool, because I've had times where people misinterpreted and got annoyed at what I was saying as they were so dead set on their beliefs.