Dinoflagellates lowering nutrients

sixty_reefer

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During my research on a different subject I’ve stumbled into this article


and this one that talks of the stressed phosphates events


The articles/study’s implie that some species of phytoplankton have the ability to release Dissolved Organic Carbon into the water column, the same in a enclosed aquarium will cause nutrients to be depleted and aid there growth as heterotrophic bacteria cannot carry on getting energy without nutrients once they become fully depleted. Could this be happening in our systems and are we miss interpreting the reduction of phosphates in connection with this event with the known fact that aragonite can absorb phosphates. In other words are we in some occasions confusing phosphates stressed system with aragonite phosphates absorbing capabilities?
 
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Randy Holmes-Farley

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I'm not sure what you are asking about exactly. All photosynthetic organisms can lower nutrients, and most will release some organic carbon in various ways.
 

Dan_P

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I'm not sure what you are asking about exactly. All photosynthetic organisms can lower nutrients, and most will release some organic carbon in various ways.
It seems the questions is “how do you distinguish between the causes of PO4 depletion in an aquarium, DOC exudate stimulated uptake vs aragonite surface adsorption?”
 

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It seems the questions is “how do you distinguish between the causes of PO4 depletion in an aquarium, DOC exudate stimulated uptake vs aragonite surface adsorption?”

There’s no doubt that dinos take up phosphate.

There’s no doubt phosphate binds to exposed calcium carbonate surfaces.

Secreted organics are going to be far lower in quantity than the Dino tissue itself, and I doubt it is measurably significant in driving P uptake by other organisms, but distinguishing that small amount from the other effects is likely difficult, and frankly, not of any real value to know, IMO. What would you do with the number if you knew it?
 
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sixty_reefer

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It seems the questions is “how do you distinguish between the causes of PO4 depletion in an aquarium, DOC exudate stimulated uptake vs aragonite surface adsorption?”
Yes, that was the thought
 
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sixty_reefer

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There’s no doubt that dinos take up phosphate.

There’s no doubt phosphate binds to exposed calcium carbonate surfaces.

Secreted organics are going to be far lower in quantity than the Dino tissue itself, and I doubt it is measurably significant in driving P uptake by other organisms, but distinguishing that small amount from the other effects is likely difficult, and frankly, not of any real value to know, IMO. What would you do with the number if you knew it?
In the article I’ve read phosphates get depleted at a rapid rate, for example I had a recent episode of dinoflagellates that caused my phosphates to deplete due to the availability of Doc and it took 0.8 pppm of dosing phosphates over a 6 hour period to get phosphates available again in the system, previously to that I’ve had a experiment tank that I overdosed Doc intentionally and after the bloom the system become a phosphates sinkhole were over 5 ppm of phosphates were added to that particular system without ever being readable, only glass and cycled water was in that system. What microbe would be using so much phosphates in the system or is there a chemical reaction that I may be overlooking?
 
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In the article I’ve read phosphates get depleted at a rapid rate, for example I had a recent episode of dinoflagellates that caused my phosphates to deplete due to the availability of Doc and it took 0.8 pppm of dosing phosphates over a 6 hour period to get phosphates available again in the system, previously to that I’ve had a experiment tank that I overdosed Doc intentionally and after the bloom the system become a phosphates sinkhole were over 5 ppm of phosphates were added to that particular system without ever being readable, only glass and cycled water was in that system. What microbe would be using so much phosphates in the system or is there a chemical reaction that I may be overlooking?

You detected a phosphate decline.

You attribute it, without evidence, to a DOC effect.

Just like any rapidly growing photosynthetic organism, dinos take up a lot of phosphate directly.

Organisms in a reef tank might use a fair amount to grow (maybe up to around 0.3 ppm per day), but not 3 ppm per day (imo).
 

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In the article I’ve read phosphates get depleted at a rapid rate, for example I had a recent episode of dinoflagellates that caused my phosphates to deplete due to the availability of Doc and it took 0.8 pppm of dosing phosphates over a 6 hour period to get phosphates available again in the system, previously to that I’ve had a experiment tank that I overdosed Doc intentionally and after the bloom the system become a phosphates sinkhole were over 5 ppm of phosphates were added to that particular system without ever being readable, only glass and cycled water was in that system. What microbe would be using so much phosphates in the system or is there a chemical reaction that I may be overlooking?
I've experienced a dino outbreak in an aquaculture system that I manage the automated testing regime.

I've did not notice any decline in phosphates in that system. It just stayed put at 0.1ppm
 

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You detected a phosphate decline.

You attribute it, without evidence, to a DOC effect.

Just like any rapidly growing photosynthetic organism, dinos take up a lot of phosphate directly.

Organisms in a reef tank might use a fair amount to grow (maybe up to around 0.3 ppm per day), but not 3 ppm per day (imo).
I recently placed a piece of live rock rubble from my aquarium into Instant Ocean fortified with 20 ppm nitrate and 2 ppm phosphate. The live rock had been with large Mexican turbo snails which means all surfaces are mowed down very short, but definitely not devoid of algae.

The rock volume was about 0.039 L and the Instant Ocean volume 0.2 L. The container for the experiment had a working volume of 0.25 L. The water was aerated with humidified air and illuminated with a full spectrum LED grow light. Light intensity was 20,000 lux (sunlight is 100,000 lux). The 20 ppm nitrate and 2 ppm phosphate concentrations were undetectable by Hanna Checkers within 24 hours.

I am not sure about the ratio of rock to water as it compares to an average reef tank, but would guess it was on the high side (~20% of the working volume), but to Randy’s point, micro and mowed down macro algae under bright light can be big nutrient consumers, making it tricky to explain a nutrient fluctuation to a particular alga species.
 
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sixty_reefer

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You detected a phosphate decline.

You attribute it, without evidence, to a DOC effect.

Just like any rapidly growing photosynthetic organism, dinos take up a lot of phosphate directly.

Organisms in a reef tank might use a fair amount to grow (maybe up to around 0.3 ppm per day), but not 3 ppm per day (imo).
Would you put it down to aragonite? Even though the system have been stable for a fair amount of time?
 

Randy Holmes-Farley

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Would you put it down to aragonite? Even though the system have been stable for a fair amount of time?

Exposed aragonite will bind phosphate any time you try to raise it, and it will release phosphate any time you try to lower it.
 
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sixty_reefer

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I've experienced a dino outbreak in an aquaculture system that I manage the automated testing regime.

I've did not notice any decline in phosphates in that system. It just stayed put at 0.1ppm
According to the article not all species cause a decline in nutrients
 
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sixty_reefer

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Exposed aragonite will bind phosphate any time you try to raise it, and it will release phosphate any time you try to lower it.
That’s plausible although I have witnessed happening before in a system that didn’t contain Aragonite.


This time around it didn’t affect nitrates just phosphates.
 
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sixty_reefer

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I recently placed a piece of live rock rubble from my aquarium into Instant Ocean fortified with 20 ppm nitrate and 2 ppm phosphate. The live rock had been with large Mexican turbo snails which means all surfaces are mowed down very short, but definitely not devoid of algae.

The rock volume was about 0.039 L and the Instant Ocean volume 0.2 L. The container for the experiment had a working volume of 0.25 L. The water was aerated with humidified air and illuminated with a full spectrum LED grow light. Light intensity was 20,000 lux (sunlight is 100,000 lux). The 20 ppm nitrate and 2 ppm phosphate concentrations were undetectable by Hanna Checkers within 24 hours.

I am not sure about the ratio of rock to water as it compares to an average reef tank, but would guess it was on the high side (~20% of the working volume), but to Randy’s point, micro and mowed down macro algae under bright light can be big nutrient consumers, making it tricky to explain a nutrient fluctuation to a particular alga species.
Wouldn’t the snail digestive system affect the overall results of this experiment? If they where to be grazing on the algae they would be producing Doc indirectly I believe
 

Randy Holmes-Farley

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According to the article not all species cause a decline in nutrients

All growing photosynthetic organisms must get N and P (and other trace elements) from somewhere.

Slow growers will have a smaller effect.
 
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Wouldn’t the snail digestive system affect the overall results of this experiment? If they where to be grazing on the algae they would be producing Doc indirectly I believe

Like people, I would not assume snails produce much DOC, but they might. They certainly produce POC (particulates) since you can see it. They will also secrete inorganic waste N and P.
 
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sixty_reefer

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All growing photosynthetic organisms must get N and P (and other trace elements) from somewhere.

Slow growers will have a smaller effect.
Apologies I meant to say not all species release Doc into the water column that by affect cause a rapid decrease in nutrients
 
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sixty_reefer

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Like people, I would not assume snails produce much DOC, but they might. They certainly produce POC (particulates) since you can see it. They will also secrete inorganic waste N and P.
My thought was along the DOM and the carbohydrates in the algae that will become glucose, on such a small volume of water it can affect the results significantly, 20ppm in 0.25 litres and 20ppm in 250 litres are considerably different, the small amount of glucose could make the results inaccurate to scale.
 
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My thought was along the DOM and the carbohydrates in the algae that will become glucose, on such a small volume of water it can affect the results significantly, 20ppm in 0.25 litres and 20ppm in 250 litres are considerably different, the small amount of glucose could make the results inaccurate to scale.

Tests on reef tanks show much lower organic carbon than that, certainly, but are unable to demonstrate the turnover.
 

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Wouldn’t the snail digestive system affect the overall results of this experiment? If they where to be grazing on the algae they would be producing Doc indirectly I believe
Rocks were taken from aquarium, rinsed in medium and tested. The snails were not part of the experiment. Sorry for the confusion.
 

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