What you need to know about copper and coral

[HighlandReefer]

Thanks for the extra details, Habib.

Enlight that the organic ligands most likely absorb 99.5% or better of copper ions, rather than 90% of the cooper ions I was using as a safe ratio, it seems to me that 30 ppb total copper would be plenty safe for a recommended total copper level in a reef aquarium.

Total copper levels above 60 ppb is definitely pusing the line IMO. At 99.5 % absorbtion & 60 ppb total copper this would result in toxic ionic copper levels around 3 ppb.

 

[HighlandReefer]

From this article it appears that common foods added to reef aquariums do provide plenty of the organic lignands to asorb ionic copper quickly & keep rather safe levels.

Acute copper toxicity in the euryhaline copepod Acartia tonsa: implications for the development of an estuarine and marine biotic ligand model
http://onlinelibrary.wiley.com/doi/10.1002/etc.212/full

"Abstract

Copepods (Acartia tonsa) were exposed (48 h) to waterborne, diet-borne (non-Cu-equilibrated and Cu-equilibrated food), and waterborne plus diet-borne Cu in either the absence or the presence of food (diatom Thalassiosira weissflogii). Toxicity tests were run in different salinities (5, 15, and 30 ppt) together with measurements of physicochemical parameters and total and dissolved Cu concentrations in the experimental media. Results show that most of the toxic Cu fraction was in the dissolved phase. In general, Cu toxicity was higher in low (5 ppt) than in high salinity (30 ppt), regardless of the pathway of Cu exposure tested. In the absence of food, data clearly indicate that differences in waterborne Cu toxicity can be explained by changes in water chemistry. However, addition of food (either non-Cu-equilibrated or Cu-equilibrated) to the experimental media protected against acute Cu toxicity in salinities 5 and 15 ppt, suggesting that A. tonsa requires extra energy to cope with the stressful condition imposed by Cu exposure associated with the ionoregulatory requirements in low salinities. For diet-borne exposure, a very high Cu concentration was necessary to precontaminate the diatoms to a level resulting in copepod mortality. Therefore, availability of food exerted a more important positive impact in protecting against acute Cu toxicity than its potential negative impact via contamination resulting in toxicity. Findings indicate the need for incorporation of both salinity and food in a future biotic ligand model (BLM) version for Cu in estuarine and marine waters. In this context, the euryhaline copepod A. tonsa would be a suitable model species with which to perform experiments to validate and calibrate any future saltwater BLM. Environ. Toxicol. Chem. 2010; 29:1834"“1840. © 2010 SETAC"

 

[tmz]

Thank you Habib for the explanation.
I'd still like to find an article that would fill my brain with knowledge by allowing it to take up the information by passive diffusion.

Hi Randy,

"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%). "

Just trying to make sense of the article Cliff posted and relate it to your work to ascertain if it's reasonable to think lower ph in reef tank ranges contributes to total copper toxicity.Perhaps that is unknowable.

In the species specific breakout table in the article, species representing less than 5% are noted as not shown. CuSO4 is listed but without % levels just check marks. CuOH2 is not listed at all . CuOH+ drops a little from 4.7% at 8.1ph to 3.8% at 7.4ph as the Cu++ rises from 7.67% to 31.8%.:fish2:

 

[Randy Holmes-Farley]

Just trying to make sense of the article Cliff posted and relate it to your work to ascertain if it's reasonable to think lower ph in reef tank ranges contributes to total copper toxicity.Perhaps that is unknowable.

I wouldn't make that conclusion without seeing a tox experiment in seawater at various pH values.

 

[HighlandReefer]

"Findings indicate the need for incorporation of both salinity and food in a future biotic ligand model (BLM) version for Cu in estuarine and marine waters."

It seems to me that future copper toxicity studies in the marine environment should incorporate foods (ligands) and provide more realistic results to work with. Otherwise one is left trying to interpret meaningless data in the real world.

 

[tmz]

Thanks Randy.

 

[Randy Holmes-Farley]

"Findings indicate the need for incorporation of both salinity and food in a future biotic ligand model (BLM) version for Cu in estuarine and marine waters."

It seems to me that future copper toxicity studies in the marine environment should incorporate foods (ligands) and provide more realistic results to work with. Otherwise one is left trying to interpret meaningless data in the real world.

I agree. Ron Shimek in some sea urchin larvae tox studies found that copper in new salt water was substantially more toxic than the same amount of copper in used aquarium water, presumably due to organic complexation.

 

[HighlandReefer]

Copper complexation by fulvic acid affects copper toxicity to the larvae of the polychaete Hydroides elegans (2007)
http://www.sciencedirect.com/science/article/pii/S0141113607000724

From it:

"Abstract

Copper toxicity is influenced by a variety of environmental factors including dissolved organic matter (DOM). We examined the complexation of copper by fulvic acid (FA), one of the major components of DOM, by measuring the decline in labile copper by anodic stripping voltammetrically (ASV). The data were described using a one-site ligand binding model, with a ligand concentration of 0.19 μmol site mg−1 C, and a log K′ of 6.2. The model was used to predict labile copper concentration in a bioassay designed to quantify the extent to which Cu"“FA complexation affected copper toxicity to the larvae of marine polychaete Hydroides elegans. The toxicity data, when expressed as labile copper concentration causing abnormal development, were independent of FA concentration and could be modeled as a logistic function, with a 48-h EC50 of 58.9 μg l−1. However, when the data were expressed as a function of total copper concentration, the toxicity was dependent on FA concentration, with a 48-h EC50 ranging from 55.6 μg l−1 in the no-FA control to 137.4 μg l−1 in the 20 mg l−1 FA treatment. Thus, FA was protective against copper toxicity to the larvae, and such an effect was caused by the reduction in labile copper due to Cu"“FA complexation. Our results demonstrate the potential of ASV as a useful tool for predicting metal toxicity to the larvae in coastal environment where DOM plays an important role in complexing metal ions."

 

[HighlandReefer]

This would be a good study to read in its entirety.


Effects of using synthetic sea salts when measuring and modeling copper toxicity in saltwater toxicity tests
W. Ray Arnold1,*, Jeffrey S. Cotsifas2, Anna R. Winter3, Joel S. Klinck4, D. Scott Smith5, Richard C. Playle3Article first published online: 9 DEC 2009

http://onlinelibrary.wiley.com/doi/10.1897/06-215R1.1/abstract

"Abstract

Synthetic sea salts are often used to adjust the salinity of effluent, ambient, and laboratory water samples to perform toxicity tests with marine and estuarine species. The U.S. Environmental Protection Agency (U.S. EPA) provides guidance on salinity adjustment in its saltwater test guidelines. The U.S. EPA suggests using commercial sea salt brands, such as Forty Fathoms® (now named Crystal Sea Marinemix®, Bioassay Grade), HW Marinemix®, or equivalent salts to adjust sample salinity. Toxicity testing laboratories in Canada and the United States were surveyed to determine synthetic sea salt brand preference. The laboratories (n = 27) reported using four brands: Crystal Sea Marinemix (56%), HW Marinemix (22%), Instant Ocean® (11%), and Tropic Marin® (11%). Saline solutions (30 g/L) of seven synthetic sea salts were analyzed for dissolved copper and dissolved organic carbon (DOC) content. Brands included those listed above plus modified general-purpose salt (modified GP2), Kent Marine®, and Red Sea Salt®. The synthetic sea salts added from <0.1 to 1.2 μg Cu/L to the solution. Solutions of Crystal Sea Marinemix had significantly elevated concentrations of DOC (range = 5.4–6.4 mg C/L, analysis of variance, Tukey, a = 0.05, p < 0.001) while other brands generally contained <1.0 mg C/L. The elevated DOC in Crystal Sea Marinemix was expected to reduce copper toxicity. However, the measured dissolved copper effective concentration 50% (EC50) for Crystal Sea Marinemix was 9.7 μg Cu/L, similar to other tested sea salts. Analysis indicates that the organic matter in Crystal Sea Marinemix differs considerably from that of natural organic matter. On the basis of consistently adding little DOC and little dissolved copper, GP2 and Kent Marine are the best salts to use."

 

[Habib]

Hey Cliff!

That one pretty much shows what I , Randy and several others have been saying for years, namely that many salt studies are flawed by giving e.g. incorrect high copper values like 30 microgram/L.
This one gives more reasonable and at least for some salts values of around 1 microgram/liter.


This is also interesting from your quote:
on. Solutions of Crystal Sea Marinemix had significantly elevated concentrations of DOC (range = 5.4–6.4 mg C/L.

The above might be a possibility of the bleaching events in aquariums switching to that salt. If for instance the DOC made heavy metals bioavailable.

 

[Randy Holmes-Farley]

I agree, it is very interesting that all the mixes studied has 1 ppb or less copper.

Wonder what the DOC is in CSM?

 

[HighlandReefer]

The table from the above link:


<a href="http://www.flickr.com/photos/17468782@N07/6686081215/" title="Copper concentration in saltmixes by cliffbabcock, on Flickr"><img src="http://farm8.staticflickr.com/7024/6686081215_6171262bbc.jpg" width="500" height="198" alt="Copper concentration in saltmixes"></a>

 

[Habib]

While searching for other things, I stumbled on this very nice and detailed article.

http://service004.hpc.ncsu.edu/toxi...tial effects of Cu on 3 species of corals.pdf

 

[Randy Holmes-Farley]

Wow, great article, showing that 10 ppb copper is already so much it is slowing growth in corals by more than 50% compared to 2 ppb.

The only caveat is that they created a fresh free copper solution just prior to exposure to the corals, which may not reflect the copper types present in an ongoing reef aquarium (where it is likely organic-bound and possiibly less toxic).

 

[Habib]

Yes, but they have to do that to approach as much as possible a non-organically bound copper concentration and also maintain a as steady as possible constant concentration.

 

[tmz]

Thankyou for the article

 

[HighlandReefer]

I believe the most important aspect discovered in this research is that copper toxicity can vary considerably from specie to specie. Hence, "suggesting different mechanisms of toxicity and/or susceptibility. This may be driven, in part, by differences in the algal symbiont communities of the coral species in question."

I remember reading another article where they found that differences in the specie of symbionts differ considerably from location to location in the same coral specie, so perhaps copper toxicity can vary as well within the same specie.

 

[Randy Holmes-Farley]

I remember reading another article where they found that differences in the specie of symbionts differ considerably from location to location in the same coral specie, so perhaps copper toxicity can vary as well within the same specie.

I've heard copper toxicity is especially problematic for corals living in certain parts of Maryland.

 

[HighlandReefer]

:lol:

That's because we have a different type of copper in Maryland. In Mass., I believe they will have a problem adding extra r to it. Perhaps coppa.

 

[DeathMagnetic]

Hey guys,

so i am setting up a used tank ( 120 gallon RR ) that was used for freshwater back in the day...

where can i get a low level test kit to determine if there is any residual copper in it ?

** not saying it ever had any .. just want to be sure !

thanks !

Joe