Iron, Silica, and Iodine and Dinoflagellates

[andrewey]

The role of iron in the growth of dinoflagellates is well characterized, so nothing written here is novel- I simply wanted to validate a pet theory of mine and provide documentation in case anyone finds this post of any interest later.

I set up an experiment* and dosed experimental containers containing large cell amphidinium with either iron, silicon, or iodine. Silica, in the form of sodium silicate, seemed to have little effect on dinoflagellate density, but as suggested by @taricha , I noticed an increase in the density of various diatoms. Iodine does not seem to be a limited nutrient in my two month old saltwater samples, as dinoflagellate growth was similar for iodine-dosed vs control samples. Finally, iron supplementation (in the form of Sodium feredetate) was associated with a seemingly exponential increase in population density that peaked at day 6 following iron administration.

As mentioned above, the role of iron availability in dinoflagellate growth and signal transduction has been well documented in the setting of oceanic studies, however my observation was in line with my expectation that iron supplementation may promote dinoflagellate (or more precisely, large cell amphidinium) growth in typical home reef tank environments.

Take this series of observations with a grain of salt, but I think this is in line with some other hobbyist's observations that iron supplementation in the setting of dinoflagellates may promote their growth. It is unknown to what extent iron plays a role in the observation that fresh saltwater seems to promote dinoflagellate growth in the setting of an infestation, but at this time, it seems prudent to avoid dosing products containing large concentrations of iron if one is battling dinoflagellates.

*contact me if you are interested in the technical details, but treat this experiment as an observation, rather than an extremely rigorous or well-controlled experiment

 

[Dan_P]

The role of iron in the growth of dinoflagellates is well characterized, so nothing written here is novel- I simply wanted to validate a pet theory of mine and provide documentation in case anyone finds this post of any interest later.

I set up an experiment* and dosed experimental containers containing large cell amphidinium with either iron, silicon, or iodine. Silica, in the form of sodium silicate, seemed to have little effect on dinoflagellate density, but as suggested by @taricha , I noticed an increase in the density of various diatoms. Iodine does not seem to be a limited nutrient in my two month old saltwater samples, as dinoflagellate growth was similar for iodine-dosed vs control samples. Finally, iron supplementation (in the form of Sodium feredetate) was associated with a seemingly exponential increase in population density that peaked at day 6 following iron administration.

As mentioned above, the role of iron availability in dinoflagellate growth and signal transduction has been well documented in the setting of oceanic studies, however my observation was in line with my expectation that iron supplementation may promote dinoflagellate (or more precisely, large cell amphidinium) growth in typical home reef tank environments.

Take this series of observations with a grain of salt, but I think this is in line with some other hobbyist's observations that iron supplementation in the setting of dinoflagellates may promote their growth. It is unknown to what extent iron plays a role in the observation that fresh saltwater seems to promote dinoflagellate growth in the setting of an infestation, but at this time, it seems prudent to avoid dosing products containing large concentrations of iron if one is battling dinoflagellates.

*contact me if you are interested in the technical details, but treat this experiment as an observation, rather than an extremely rigorous or well-controlled experiment

Very nice demo! I am interested in growing dinoflagellates. Would post your experimental conditions? I am sure others would be interested. Lots to discuss here.

Dan

 

[andrewey]

Sure thing! As already mentioned, I was looking for large changes and wasn't too focused on ensuring experimental rigor or focused on reproducibility, but here's what I did.

For each element, I set up three containers (5 gallon buckets), each with their own heater and 2lbs of live rock. Two gallons of old (2 months) saltwater was utilized in each container and all top offs with RODI was handled manually. Temperature (78.0-78.4) and pH (7.8-7.95) monitoring were done using my current Apex and a spare aquacontroller III. Lighting was provided by a LED black box- as the width of three 5 gallon buckets was larger than the LED coverage, buckets were rotated twice a day to try and provide equivalent lighting (photoperiod of 8 hours, 50% blue, 25% white 24" above the surface of the water).

As one of my current tanks has large cell amphidinium, I simply collected 20mL of sample and confirmed via microscopy the samples mainly contained large cell amphidinium (with traces of the normal marine microfauna). As I no longer had access to a centrifuge, I simply shook up the vial to try and disperse the dinoflagellates into the water column, then dosed 5mL into each container. I let them sit for two weeks while I let the population of large cell amphidinium come closer to an equilibirium*.

One container was designated a control and the other two containers received the following doses (all elements were dosed individually and new water/rock was utilized and buckets/heaters/power heads were sterilized with bleach between trials:

Iron- Dosed 1mL and 0.2mL of Brightwell Ferrion (an expected increase of 0.5 and 0.1ppm, respectively). I did not measure the starting or ending iron concentration, as I do not own an iron test kit.

Silica- Dosed 1mL and 0.5mL of Brightwell Sponge Excel (an expected increase of 2 and 1ppm, respectively). I did not test silica levels.

Iodine- Dosed Lugol's solution diluted with RO water to a concentration equivalent to 1/350 and 1/700mL. I did not test iodine levels. Values based on maximum daily dosing concentrations (per Brightwell) to achieve 0.05ppm iodine concentration.

All containers had random water column and rock surface samples drawn daily to monitor population density.

*Note- I had originally planned on only resting the containers for one week, however I continued to observe seemingly linear growth patterns at one week, so I gave the samples two weeks until the population growth of large cell amphidinium slowed.

 

[Dan_P]

Sure thing! As already mentioned, I was looking for large changes and wasn't too focused on ensuring experimental rigor or focused on reproducibility, but here's what I did.

For each element, I set up three containers (5 gallon buckets), each with their own heater and 2lbs of live rock. Two gallons of old (2 months) saltwater was utilized in each container and all top offs with RODI was handled manually. Temperature (78.0-78.4) and pH (7.8-7.95) monitoring were done using my current Apex and a spare aquacontroller III. Lighting was provided by a LED black box- as the width of three 5 gallon buckets was larger than the LED coverage, buckets were rotated twice a day to try and provide equivalent lighting (photoperiod of 8 hours, 50% blue, 25% white 24" above the surface of the water).

As one of my current tanks has large cell amphidinium, I simply collected 20mL of sample and confirmed via microscopy the samples mainly contained large cell amphidinium (with traces of the normal marine microfauna). As I no longer had access to a centrifuge, I simply shook up the vial to try and disperse the dinoflagellates into the water column, then dosed 5mL into each container. I let them sit for two weeks while I let the population of large cell amphidinium come closer to an equilibirium*.

One container was designated a control and the other two containers received the following doses (all elements were dosed individually and new water/rock was utilized and buckets/heaters/power heads were sterilized with bleach between trials:

Iron- Dosed 1mL and 0.2mL of Brightwell Ferrion (an expected increase of 0.5 and 0.1ppm, respectively). I did not measure the starting or ending iron concentration, as I do not own an iron test kit.

Silica- Dosed 1mL and 0.5mL of Brightwell Sponge Excel (an expected increase of 2 and 1ppm, respectively). I did not test silica levels.

Iodine- Dosed Lugol's solution diluted with RO water to a concentration equivalent to 1/350 and 1/700mL. I did not test iodine levels. Values based on maximum daily dosing concentrations (per Brightwell) to achieve 0.05ppm iodine concentration.

All containers had random water column and rock surface samples drawn daily to monitor population density.

*Note- I had originally planned on only resting the containers for one week, however I continued to observe seemingly linear growth patterns at one week, so I gave the samples two weeks until the population growth of large cell amphidinium slowed.

Thanks for the details. You thought this through quite carefully. One question. What is “two month old saltwater”? How do I prepare this?

 

[andrewey]

A sample of convenience! I had stopped performing water changes for the last two months, so I simply used that water after it was run through a 1 micron sock. I didn't want to use fresh saltwater for obvious reasons and my hope was that the old saltwater would have lower concentrations of the tested elements from consumption via sponges, diatoms, cheato, etc. Obviously, a better experiment would have confirmed the starting levels to determine whether any of the elements were limited (which opens up its own can of worms defining "limited"), but I opted for a quick and dirty experiment to see if the addition of an element, whether or not it was depleted in any meaningful way, was associated with an increase in dino growth compared to control.

 

[andrewey]

If you were trying to grow out a dino population as fast as possible for your experiments, I would probably grow them out in fresh salt water to ensure nothing was rate limiting their growth.

 

[Dan_P]

A sample of convenience! I had stopped performing water changes for the last two months, so I simply used that water after it was run through a 1 micron sock. I didn't want to use fresh saltwater for obvious reasons and my hope was that the old saltwater would have lower concentrations of the tested elements from consumption via sponges, diatoms, cheato, etc. Obviously, a better experiment would have confirmed the starting levels to determine whether any of the elements were limited (which opens up its own can of worms defining "limited"), but I opted for a quick and dirty experiment to see if the addition of an element, whether or not it was depleted in any meaningful way, was associated with an increase in dino growth compared to control.

Thanks for the reply! This helps.

 

[taricha]

You're killing it @andrewey ! this is fantastic.

If you were trying to grow out a dino population as fast as possible for your experiments, I would probably grow them out in fresh salt water to ensure nothing was rate limiting their growth.

You would think so, but some doing research on dinos find that they can be tricky to culture in traditional ways. We have more success growing them in tank water!

 

[andrewey]

@taricha - fascinating, have you any guesses for why that might be?

 

[taricha]

@taricha - fascinating, have you any guesses for why that might be?

If I were going to make a guess about aquarium water, it would be that the mixotrophic nature of the Dinos means that old aquarium water might be better suited to the dinos relative to their competitors vs culture media based on forms of available nutrients and microorganisms. Maybe the organics and bacteria that don't show up on test kits as "nutrients" are sufficient to grow dinos.

but I think in the case of the people trying to culture up dinos in a lab from a mixed sample, the bigger issue is probably that algae growth medium is traditionally far too rich for the task. I say this based on what we see in the hobby, but also to illustrate. I ran across a paper the other day that was saying that prorocentrum grow so slowly - well under one division per day - that their cycle of division is totally untethered to the 24 hour clock. They can't keep up with a 24-hour day!
So if you have a mixed sample of dinos, and you give it some algae growth media, then it would have to be really really clean for the dinos to not get overrun by a million other faster growers.

 

[Miller535]

I personally believe that dinos LOVE all heavy metals. I have both large and small cell amphidinium. My NO3 and PO4 bottomed out. BUT at the same time due to a few things, I ended up with 40ppb copper, zinc, and a few other nasties. And I think that was a HUGE factor in my dinos exploding initially. I eventually got the metals under control and did notice a decline.

 

[Miller535]

I have also read where dinos love elements such as Potassium. Which I can prove through ICP test depleted in my tank month by month quickly. And potassium is an element that is said to deplete so slow most reefers never have to dose it.