What you need to know about copper and coral

[HighlandReefer]

The book I just read states that the organic fraction of copper in the ocean (mostly bound with ligands) is between 89%-99%. If you use say 90% to be on the safe side, this would mean total copper levels above 30 ppb total copper (3 ppb inorganic copper) could be a problem from the way I understand it. From the study completed in the past in reef tanks, they did find hobbyists with higher levels than 30 ppb total copper in their tanks (up to 80 ppb IIRC). This agrees with some results posted by hobbyists who had levels in the 40-50 ppb total copper range (if we can depend on AWT's results).

With hobbyist now commonly dosing copper (inorganic) along with that introduced in a reef tank though supplements (inorganic copper), food, salt mixes (inorganic)....etc, I would assume that inorganic copper could be a problem for some hobbyists.

[bif24701]

So then would it be a good idea to run a Poly Filter regularly? So insure that this is never a problem? Is testing for copper and negative results enough to ensure safety?

[HighlandReefer]

I am not sure that using a Polyfilter or running Cuprisorb would grab up inorganic copper fast enough in a reef tank should a hobbyist unknowingly increase inorganic copper say by adding too much mag supplement at one time. The time period from scientific research states it only takes hours for damages to occur. I think perhaps prevention is the best policy. I suspect that running GAC on a regular basis will help lower total copper levels effectively.

Certainly, if you suspect that copper is a problem, then running a product to lower copper levels can be helpful.

I personally question the use of inorganic copper as a supplement to reduce coral symbionts for enhancing colors. I believe this is pushing a very fine line and is risky.

It would be nice to know what one's tank total copper level is to make sure the tank is being run properly. This can only be accomplished by sending samples off to a proper seawater lab. This may be more cost effective than running a copper absorbing product 24/7, along with taking the proper precautions. I believe ENC Labs charges around $65.00 to run a copper test.

[Randy Holmes-Farley]

I too am not a fan of that idea, but it might be an appropriate choice for some folks to make depending on their husbandry philosophy. It may make pastel corals that some folks like, but I question whether it is a good idea for all the other microlife in the tank. It is highly unlikely that zoox are the only sensitive organisms that are partly killed by the additives. I guess it all depends on whether you want a semi-natural ecosystem, or a support system designed specifically to maintain an unusual color form of certain corals.

[HighlandReefer]

One thing I found troubling from reading through all the articles I have regarding copper levels and its toxicity, is that one needs to be very careful regarding analyzing the research. Many articles simply state copper and do not define which specie of copper. Some define copper in the article but not in the summary. Some quote one article referring to inorganic copper (Cu++) levels and then turn around and quote another article referring to total copper, yet do not state this.

The worst one was an EPA report which never defined copper species they were talking about and cited both total copper and Cu++ studies without mentioning this fact.

[tmz]

I have never dosed copper intetionaly., so I don't know if it would create designer corals or not. Color in my corals without it is quite good to my eye though.

[Habib]

Originally Posted by HighlandReefer

Habib,

I know you did quite a bit of research to write your article:

Feature Article: Toxicity Of Trace Elements: Truth Or Myth?
http://www.advancedaquarist.com/2003/5/aafeature

What is the break-down between inorganic and organic copper on average say in the ocean. Something comes to me that it is in the area of 90-98% organic copper?

Perhaps that's where they get the recommendation of 30 ppb copper as total copper.

LOL on the last part!


Most of the heavy metals are bound to ligands.

More reading in post # 17 of

http://archive.reefcentral.com/forum...ht=siderophore

And there is another ancient mega (mega size and mega headache) thread.

[Randy Holmes-Farley]

Originally Posted by Habib

And there is another ancient mega (mega size and mega headache) thread.

Ah, the good old days.

[tmz]

On a related note, I keep frags and mini colonies of many of the sps , in a variety of lighting conditions , varying wattage and k ratings, with and without actinic supplementation and with and without led supplemenation . The variation in color that occurs is significant to a point where one could easily doubt it was the same coral by looking at it . Perhaps much of the color claim associated with dosing metals relates to enhaced water clarity and consequent lighting enhancements resulting from other elements of these systems geared to bacterial growth and nutrirent reduction . Reorganized organics , PO4 reduction ,NO3 reduction and feeding make a difference too, imo.

[Habib]

Originally Posted by Randy Holmes-Farley

Ah, the good old days.

[HighlandReefer]

Habib,

Thanks much for the link. Great info.

"Tatu: Think twice , NO thrice before posting anything"

This appies to me as well.


I wish I was around in the good old days.




Any guess for the amount of time that it may take for inorganic copper introduced into a reef tank to bind to organics in a reef tank? Hours, days or perhaps a week?

I will get around to reading the links you posted.

[Habib]

I wish I was around in the good old days.

Were men were men and dinosaurs were dinosaurs.

Any guess for the amount of time that it may take for inorganic copper introduced into a reef tank to bind to organics in a reef tank? Hours, days or perhaps a week?

I will get around to reading the links you posted.

Minutes, hours a day or so. Treating fishtanks with ionic copper requires regular dosages because copper gets bound to decoration and organics.

So it's (bio)availability reduces relatively rapidly.

[HighlandReefer]

"Treating fishtanks with ionic copper requires regular dosages because copper gets bound to decoration and organics."

Any personal experiences or theories based perhaps on science you care to share regarding dosing copper. There could be more to this than what I have read as standard descriptions regarding supplements sold. Not much as far as scientific articles that I can find except what I have posted.

[Habib]

Cliff, with treating fishtanks I meant treating fish against diseases with copper.

E.g. http://edis.ifas.ufl.edu/fa165

[HighlandReefer]

Just reading through this article & it seems that the percentage of Cu++ in seawater almost doubles between pH 8.1 down to 7.8. Would this mean the total copper level recommendation for 30 ppb would be reduced the same amount?

Effect of Ocean acidificationon the Speciation of Metals in Seawater (2009)
http://www.tos.org/oceanography/arch...-4_millero.pdf

"Metals that form strong complexes with carbonate include Cu2+, UO22+,
and the rare earths. These metals will be most strongly affected by the change in pH, resulting in an increase in their free ionic forms. The largest percentage increase for carbonate-dominated metals is for Cu2+ (30%).

Table 1. The fraction forms of metals in seawater as a function of pH and time (Caldeira and Wickett, 2003) at 25°C
and salinity of 35. Species contributing less than 5% are not included. All the calculations are made on the free pH scale.


pH/Cu2+ Percentage:

pH 8.1 - 7.67%

pH 8.0 - 9.64%

pH 7.9 - 12.04%

pH 7.8 - 14.92%

pH 7.7 - 18.32 %

pH 7.6 - 22.26%

pH 7.5 - 26.75%

pH 7.4 - 31.76 %
-----------------------------------------------------------------------------------

When using ozone in a reef tank, this will strip the copper from organic compounds. Any guess as to how much increase in Cu++ that may occur?

[tmz]

Thanks CLiff. That's a nice table . So if I'm reading it correclty, the % of total copper present as free copper Cu 2 roughly doubles if ph drops to 7.8 form 8.1.

[HighlandReefer]

That's the way I understand it, yes.

Would the recommendation for total copper in a reef tank be reduced to say 15 ppb at a pH level of 7.8?

My concern is that Cu++ is toxic in short periods of time to coral, perhaps hours and the damage is done.

[tmz]

At first galance it seems to support a case for ph closer to or above nsw values. I doubt we'll know whether a tank is at 30ppb or 15ppb at the hobby level.

I didn't see anything in the study that would give a sense of time other than projections over years for unbinding though and the fromulae are too difficult for me to handle and extrapolate. I'd reckon it would be a relatively fast speciation but might be slower for the portion of total copper bound to refractory organics. Don't know.

[HighlandReefer]

Chemical speciation of trace metals in seawater: a review (2006)
http://mounier.univ-tln.fr/rcmo/php_biblio/PDF/5233.pdf

From it:

"Chemical Model of Trace Metals

One of the purposes for the chemical speciation of trace metals
is application to chemical modeling of the ocean. Many kinds
of models for ocean systems have been proposed to have a
better understanding of ocean systems and to predict the future
of the oceanic environments; it includes physical models i.e.,
general ocean circulation model,137 biogeochemical models138,139
and ecological models.140 There are a few oceanic models
including chemical reactions, especially, the complexation of
bioactive trace metal ions with ligands in dissolved organic and
particulate matter. Recently, a chemical model including metal
complexation has been proposed.141

Chemical speciation studies58,67,99,136 have revealed that two
types of dissolved organic ligands are related to the
complexation of trace metals, such as Cu and Zn, in seawater.
However, there is little information on the ecological and
biogeochemical roles of each ligand, except for the metal
buffering capacity.142 In order to elucidate the ecological roles
of dissolved organic ligands in the marine environment,
therefore, a chemical model, including the relationship between
the total Cu and free Cu2+ concentrations in the presence of each
ligand, is effective
.
According to our present knowledge of dissolved organic
ligands,69 the concentrations in seawater are 1 – 3 nM for L1 and
20 – 60 nM for L2. The free Cu2+ concentration in seawater
reflects the reactivity of Cu, and is directly related to the
ecological role to marine microorganisms.31,32 The free Cu2+
concentration in seawater was calculated as a function of the
total Cu concentration based on the chemical equilibrium
model,141 in which the effects of Ca and Mg were taken into
account. The result is shown in Fig. 2. For the presence of only
a stronger organic ligand (L1), the free Cu2+ concentration
showed a sigmoid curve in the range of natural occurring Cu
concentrations in seawater; the free Cu2+ concentration was
maintained at a lower level (less than 1 pM) when the total Cu
concentration was less than that of the stronger organic ligand,
whereas the free Cu2+ concentration steeply increased at a Cu
toxic level (more than 10 pM)30,143,144 when the total Cu
concentration exceeded that of the stronger organic ligand. On
the other hand, for the weaker organic ligand (L2), the free Cu2+
concentration showed a different behavior, in which the free
Cu2+ concentration was maintained at lower level (less than 10
pM) within the natural occurring concentration range of the
total Cu in seawater. The increase in the ligand concentration
shifts the free Cu2+ concentration to lower levels. These
findings suggest that a weaker ligand plays a more significant
role than a stronger ligand to reduce Cu toxicity to marine
microorganisms under higher Cu conditions. This result is
consistent with the finding that a weaker ligand can dominate
Cu speciation in coastal water with higher Cu concentrations.145"

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pM copper concentration = what ppb?

I wonder which types of lignand would be more likey present in a tank without macroalgae?

[Randy Holmes-Farley]

I wouldn't jump to conclusions here.

I discuss the various unchelated forms of copper in this article:

http://reefkeeping.com/issues/2003-0...ture/index.php

from it:

"The portions of metals in seawater that are not bound to organic materials are very complicated in their own right. Copper, for example, takes at least 7 different soluble inorganic forms in seawater.4 It is comprised of Cu++ (3.9% of the inorganic copper), CuOH+ (4.9%), Cu(OH)2 (2.2%), CuSO4 (1%), CuCO3 (73.8%), Cu(CO3)2-- (14.2%) and Cu(HCO3- )+ (0.1%). "


OK, so we have an idea of the forms copper takes in seawater when not complexed to organics. But what we do not know is which of these forms most contribute to toxicity. They are all rapidly converted, but I would be very hesitant to assume that free Cu++ is a lot more toxic than CuSO4 or Cu(OH)2 ion pairs. In fact, since the latter two are neutral, it might actually be absorbed more readily than charged forms and hence might be more toxic.

[Randy Holmes-Farley]

Originally Posted by HighlandReefer

When using ozone in a reef tank, this will strip the copper from organic compounds. Any guess as to how much increase in Cu++ that may occur?

The toxicity of metals is one of the hypothesized ways that ozone might contribute to HLLE and related issues, so I think there is reason to be concerned. Could be as much as 10-fold increase if it is otherwise 90% complexed.

[HighlandReefer]

Back to the.......

"A little learning is a dang'rous thing; Drink deep, or taste not the Pierian spring: There shallow draughts intoxicate the brain, And drinking largely sobers us again."

Again, I am intoxicated with what knowledge I have aquired.

Thanks for keeping me straight Randy.

[Habib]

Originally Posted by Randy Holmes-Farley

.......
............


OK, so we have an idea of the forms copper takes in seawater when not complexed to organics. But what we do not know is which of these forms most contribute to toxicity. They are all rapidly converted, but I would be very hesitant to assume that free Cu++ is a lot more toxic than CuSO4 or Cu(OH)2 ion pairs. In fact, since the latter two are neutral, it might actually be absorbed more readily than charged forms and hence might be more toxic.

Freshwater with various anions might be able to supply the answer.


Effects of inorganic complexing on the toxicity of copper to Daphnia magna
R.W. Andrew, K.E. Biesinger, G.E. Glass
U.S. Environmental Protection Agency, Environmental Research Laboratory-Duluth, 6201 Congdon Boulevard, Duluth, Minnesota 55804, U.S.A.
Received 26 September 1976. Available online 10 April 2003.
http://dx.doi.org/10.1016/0043-1354(77)90064-1,

Abstract
Effects of carbonate-bicarbonate, orthophosphate, and pyrophosphate on the toxicity of copper (II) to Daphnia magna were studied at constant pH and total hardness. Mortality rates and reciprocal survival times were directly correlated with cupric (Cu2+) and copper hydroxy (Cu(OH)n) ion activities as determined by equilibrium calculations. Toxicity was negatively related to activities of soluble copper carbonate (CuCO3) and other complexes, and was found to be independent of dissolved copper or total copper concentrations.



There might be some for sulfate.

[Habib]

This one is, at least in my opinion, very very interesting regarding corals; uptake by passive diffusion through cell membranes.

http://www.vliz.be/imis/imis.php?module=ref&refid=60578 (most of it on that page is Dutch/Flamish but the abstract is in English, pasted here below)


Abstract:
The effect of organic complexation, salinity, and pH on the uptake and toxicity of copper in Artemia was studied. The results were compared with data on the chemical speciation and lipid solubility of copper in saline solutions.
The uptake experiments took 90 min and the toxicity tests 24h. A computer model was used to calculate the saline solution equilibrium speciation. The lipid solubility of copper was determined in a series of saline/olive oil partition tests.
Complexation of copper by EDTA reduced the uptake and toxicity of copper. Salinity had no apparent effect on both processes. The results of these uptake and toxicity experiments agreed well with the copper speciation and lipid solubility data. The effect of pH on the uptake and toxicity of copper is more complex. The uptake rate is maximal around pH 7.6 and lowest below 7.0. The toxicity increases towards alkaline conditions. These results do not relate to the speciation and lipid solubility data in a straightforward manner.
Possibly two distinct ligands determine the biological availability of copper in solution. Ionized species interact with the charged ligands present on the external surface of cell membranes (i.e. glycoproteins, proteins, polar heads of lipids) and neutral species move across the lipid bilayer by passive diffusion.

[HighlandReefer]

"Abstract
Effects of carbonate-bicarbonate, orthophosphate, and pyrophosphate on the toxicity of copper (II) to Daphnia magna were studied at constant pH and total hardness. Mortality rates and reciprocal survival times were directly correlated with cupric (Cu2+) and copper hydroxy (Cu(OH)n) ion activities as determined by equilibrium calculations. Toxicity was negatively related to activities of soluble copper carbonate (CuCO3) and other complexes, and was found to be independent of dissolved copper or total copper concentrations."

If this happens to be true in saltwater, then one might extrapolate this information by percentage, since (Cu(OH)n) does not change with lower pH down to 7.8:

Perhaps this change in Cu2+ to mean that a recommendation of highest total copper could be 22 ppb (down from 30 ppb) if the pH remains at 7.8 for a few hours?