What forms of iron are bioavailable?

Randy Holmes-Farley

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The ways that trace elements exist in reef tanks, and the way they are taken up are very complex and poorly understood. Even in the ocean these things are not always well known, despite being studied.

I thought these quotes from a paper I was reading might be of interest:

The chemical speciation of iron in the north-east Atlantic Ocean
https://www.sciencedirect.com/science/article/pii/S0967063706000161

There is still uncertainty about which form(s) of iron (organically complexed Fe(III), inorganic Fe(III), or Fe(II)) is bioavailable.

Recent work indicates that the bioavailable iron may well be inorganic Fe(III) taken up in a reductive process. Counter intuititively the concentration of such Fe(III) can be enhanced by siderophores , facilitating photochemical reduction of Fe(III) to transient Fe(II), with a subsequent re-oxidation to fresh Fe(III).

In this study, total dissolved iron averaged 0.79 nM .... the iron was 99% organically complexed, leaving a calculated inorganic Fe(III) concentration of 10.476 pM

The presence of Fe(II) shows that these waters are not at thermodynamic equilibrium. The concentration of Fe(II) was greater than that of inorganic Fe(III), indicating that this transient Fe(II) greatly changes the chemical speciation of iron.
 

mcarroll

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Hopefully this is on-topic....to my brain it seems like it. (If its not then consider it a thread bump.) ;)

I've heard of shipwrecks/artifical reefs being removed from some areas due to the negative impact on local reefs from the iron dissolving.

What is happening with the iron that corals appear to grow all over shipwrecks yet the wrecks may/are also negatively impacting reefs?
 

kecked

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I'm just replying here as a place holder till I get home to read. Randy thank you for your knowledge and willingness to share. I just wanted to stop my bad habit of thread sidetracking. I'm new to this forum and forums in general and am learning the rules. Being at a university I easily get excited and go off on research binge reading. These dinos really got my attention so want to study them in everyway I can. I am interested in Iron because I noticed that my dino problem started to get better once I took GFO out but it was not phosphate modulated because I was dosing. That leaves the iron in my gunsight. The yeast got my attention because I was told to outcompete the dinos. That was a dry hole but then this iron siderophores creped back up again. So I am interested in seeing if we can control selectively nutrients and trace minerals to control the diversity in the tank. Sort of the limiting reagent idea. Well all that plus it's just fascinating to learn. My main stay is quantum chemistry, electrical engineering, and occupational health so biology offers new fertile ground. I've never been more into my reef or felt so out to sea!
 

taricha

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Well, my background is not Chem, so I constantly run headfirst into walls where I wish I understood the chem better to get where I'm trying to go.
For those who do speak chem, reading this paper: Organic Matter Degradation Drives Benthic Cyanobacterial Mat Abundance on Caribbean Coral Reefs
They make the (not unfamiliar) case that decaying organics fuels cyano, but there's a couple of interesting comments on mechanisms involving Iron.
Some Quotes:
"Soil extracts rich in P, Fe and organic carbon enhanced the productivity of L. majuscula [Cyano] in bioassays, suggesting land runoff as a key driver of the bloom [3]. Increased dissolved organics in the water column may facilitate the transport of bio-available Fe and P to L. majuscula via the formation of Fe-organic complexes [30,31]. Recently, Fe released from corroding shipwrecks was suggested to stimulate algal/cyanobacterial assemblages in central Pacific reefs through a similar mechanism [32]."

"our results suggest that the nutrient source for BCMs [Benthic Cyano Mats] originates from OM [Organic Matter] that has settled on the seafloor and is decomposed by microbial degradation as proposed in Fig 6B. Due to the degradation, an anoxic zone develops at the sediment surface. The ensuing Fe3+ reduction leads to release of Fe3+-bound phosphate to the water column, and possibly also of Fe2+ [46]. This local nutrient release from the benthos subsequently stimulates the growth of BCMs."
Screen Shot 2018-04-04 at 5.06.45 PM.png


"Nutrient inputs from land runoff (A1) or groundwater seepage (A2) cause benthic and planktonic phototrophic blooms. Fe is largely available as a result of long-term Fe addition by the African dust [54]."

Am I interpreting this right that in the conditions of the anoxic decomposition of organic matter, Fe input from dust that would not have been considered bioavailable, then becomes bioavailable and helps drive growth of cyano mats?
 

kecked

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The paper randy posted showed that there is higher nitrate and iron at depth than at the surface. That would be consistent with this paper. I am wondering if by adding the strong led lighting we have with enhanced near uv that we are not providing additional Fe(III)->Fe(II) conversion making it more bioavailabile. It really sounds like we have underappreciated cyano in our tanks. Still digesting the first paper. I think we are learning that our attempts to control our tanks is both unnatural and unproductive. Stability in parameters yes but a natural system has its own balance. Trying to use gfo as one example to control P instead of letting the diversity do the job could be the root of many issue.

So....I am thinking to look at redox in my tank as well as iron in addition to nitrate and phosphate and see if I can find a trend. I have two infected tanks next to each other so I can try things with a control.

Ps I downloaded the paper for those without access if needed. It’s pretty easy to summarize the major points and randy did a great job of it.

So how to reduce iron all species without affecting other ions. Crown ethers not going in my tank.
I’m sure selective ion exchange resins exist. This of course would be back for corals and inverts long term. I just want to see if I see an effect. I have one tank with coral only.

Have not read fully but this is similar to what I am thinking
https://pubs.acs.org/doi/abs/10.1021/es9604018
 
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Randy Holmes-Farley

Randy Holmes-Farley

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Along these lines, I have tried to instill in some folks the caution that oxidizers like Lugols or hydrogen peroxide or reducers like vitamin C, may be altering the bioavailability of trace elements, so when folks observe effects, it may not be due to iodine supplementation or the direct effects of these additives on things like dinos.
 

kecked

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I am thinking of trying to put a low pass filter on my lights to block 500-up and measure redox. Not sure how to do it with live stuff but if the effect is there I should be able to see it with just a mercury lamp and seawater doped with iron from gfo. Might be able to do it with a mason jar floating under the lights . Isotherm I’m thinking. Overload iron to start then back off as I see an effect. This would demo the uv iron effect without living organisium effects. Plenty of variation. My toxin study is a dry hole so moving on. Should be happy not to find any I guess. Now if this works next I’ll try some dead yeast cells and see what happens. I’ll lyse them open first.
 

mcarroll

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I noticed that my dino problem started to get better once I took GFO out but it was not phosphate modulated because I was dosing

Assuming you have the typical new-tank/dry-rock/GFO/carbon-dosing oriented dino's that seem very common, then phosphates are dosed for dino's for three main reasons:
  • As a restorative measure so the tank P cycle can get back to normal from being zero'd out.
    There are many needs for dissolved P in a tank and many processes and organisms which cannot access it at ultra-low levels or otherwise compete for it well.
  • To facilitate decomposition of the thecal plates their cells leave behind during the course of a bloom.
    Otherwise bacterial action on these carbon-rich plates will persistently hold dissolve nutrients to a problematically low level.
  • To feed new dino cells so they will be able to live as autotrophs and don't continue to rely on phagotrophy due to starvation.
There's nothing "anti-dino" about phosphates that I'm aware of. :)

(Dino's present in other circumstances, but it's rare by comparison....can't speak to those circumstance.)

I've never been more into my reef or felt so out to sea!

I love that feeling. :)

Recently, Fe released from corroding shipwrecks was suggested to stimulate algal/cyanobacterial assemblages in central Pacific reefs through a similar mechanism [32]."

I know that wasn't for me, but thanks! Didn't have a reference to pull for that info earlier.

Am I interpreting this right that in the conditions of the anoxic decomposition of organic matter, Fe input from dust that would not have been considered bioavailable, then becomes bioavailable and helps drive growth of cyano mats?

I think you're on the right track, but I'm also interested if anyone thinks otherwise.

The microbial loop is the single most under-estimated aspect of the known natural world. I've got a journal article from 2013 laying somewhere around here where the author claims essentially that science has almost totally ignored the role of microbes up to that point in time. She wasn't claiming there had been no research on microbes, of course. She was testifying only on the apparent magnitude and frequency of our underestimation.

IMO our approach to reefing is the chemical one. That's mostly been good, but our lack of ecological inputs for guidance shows in some important places....like algae outbreaks and pathogen outbreaks.

It really sounds like we have underappreciated cyano in our tanks.

Yes! It's certainly not The Enemy. ;Walkingdead

Stability in parameters yes but a natural system has its own balance.

You're on a roll now! :)

(And there are some good papers out there on the topic too.)

Trying to use gfo as one example to control P instead of letting the diversity do the job could be the root of many issue.

Indeed GFO and other nutrient reducers like it are at the root often enough. I call GFO and similar tools "hacks" or "bandaids" sometimes....you might not be surprised given the general popularity of nutrient reduction that the response to those terms aren't universally positive. :D

so when folks observe effects, it may not be due to iodine supplementation or the direct effects of these additives on things like dinos.

It's definitely more complex than folks are usually imagining when they start out. ;)

Trace elements and the whole microbial loop are among the several important factors at work that seem to generally go unnoticed or under-appreciated. :rolleyes:

FWIW since dino's are on topic.. On my dino thread we focus a lot on macronutrients as they relate to ecology. But that's not a focus that's intended to rule out other potential factors like indirect effects or trace elements. Macronutrients and ecology are just the areas where we have some control, some understanding, some ability to test and where folks have actually made some progress. :)
 

kecked

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https://pdfs.semanticscholar.org/18b6/0251f41a8107d1a691e745486a270f3edba8.pdf


Good article.

https://www.sciencedirect.com/science/article/pii/S0022098104004848

I think I'm on to something here with the Iron, the Dinos, and the toxin...Rather they were on to it and I just read about it. It would be interesting to see ICP results for tanks showing dino outbreaks and toxic effects and Iron Selenium.... Might be able to mediate the effects by chelating the iron/ binding it/changing its form to be less available while mediating the infection with predation. can add iron back in once the infection is subdued and the biodiversity restored. Problem is does the other organisium need the iron too. Can we deliver it so the dinos can't use it but the others can.

Since
 
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mcarroll

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Thanks for the links!


Looks pretty good from the abstract!

BTW, full PDF is available for this one if you search thru Google Scholar. The link they have is to PDF hosted on academia.org if you want to try searching there for it.

The title is "Effects of selenium, iron and cobalt addition to growth and yessotoxin production of the toxic marine dinoflagellate Protoceratium reticulatum in culture".

Back to reading... :)
 

kecked

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moving on....https://www.sciencedirect.com/science/article/pii/S0304420301000536
making sure I don't kill myself if i try this....

I'm starting to think adding selenium or iron to a tank experiencing toxin might reduce the toxin production even if it adds to the growth. This might be supplemented like N and P are during the treatment. If I drop my Fe in my non toxic tank I am likely according to these studies force the production of toxins as the algae try to grab more Fe/Se. Toxin production might just be the algae attempt to chelate and grab these ions.

back to reading....
 
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Randy Holmes-Farley

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kecked

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http://marchettilab.web.unc.edu/research/

So went looking for organic iron and came across Ferritin of course! Looks like we might use supplementation of it to increase diatom production which if the dinos also do not use the same way might tip the scales AND keep toxin production down. Nice side is it also is skimmable so it will remove itself.

More reading......

I'm thinking if you have dinos you want to shut down the toxin production as that is what the real concern is. So if we can turn that off and also build nutrients to build the diversity we can keep the effects of the dinos down while we eliminate them. That's what I'm thinking. So can we increase growth to turn off the toxins but not so much we can't eliminate the dinos.

sorry I'm in two threads one Iron one toxin and they are crossing back and forth.
 

kecked

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So what do you think of my idea randy? I’m totally new to this. I’m kind of stream of consciousness here.
I must have toxin I can’t isolate as my little tank is now coating and all my star polyps won’t open now. That ok though as that tank has no uv fish or anything else but coral so I’m willing to mess with it.
You think ferritin dosing is worth trying or just adding some iron chloride. Thinking to start 0.5mg in 30 gallon tank and see what happens. I’m not firing up the icp or aa for this so it would be imperial. I do wonder if I can burn it out like round up does by over stimulating it to death. Would blow out my corals too though as the zoa get expelled. Just feeling thi# iron control has potential. Just not sure to add or remove iron!
 

kecked

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Yes provided I can also increase other biodiversity through increased p an n to out compete the Dino’s. Hoping uv adds the extra needed to check the extra growth.

So add iron to suppress the toxin while using the usual Dino killing process we are following from the other thread to out compete.
 

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