I just read your anemone article. Do you think strontium is bad?

[chris_h]

I just read this

Additions of strontium and other similar pollutants are not necessary for anemone health.

in this http://www.animalnetwork.com/fish2/a...wb/default.asp article that you wrote.

It appears that you think that the addition strontium is counterproductive. Could you explain this further?

[rshimek]

Hi,

Strontium is necessary in the early embryos of sea hares and some octopuses. It is also necessary for the production of stronitium sulfate skeletal rods in some species of pelagic protozoans.

It has no known use in any other animals.

In this paper:

Wright, O. P. and A. T. Marshall. 1991. Calcium transport across the isolated oral epithelium of scleractinian corals. Coral Reefs. 10:37-40.

Wright and Marshall (1991) showed that strontium significantly reduced the transport of calcium ions across coral epithelial tissues. All calcium used by corals for either metabolic processes or for calcification comes from within the animal’s tissues, not directly from the sea water surrounding it. Thus a reduction in calcium transport into the animal will directly reduce all of these processes, including calcification. The presence of significant amounts of strontium could significantly inhibit and alter all calcium requiring processes, such as muscle contraction, tissue differentiations, growth, and injury repair, by reducing the calcium uptake from the surrounding waters.

Anemone physiology and coral physiology are largely the same.

Anemones don't need any strontium at all. Neither do any other aquarium animals.

[chris_h]

Thanks. I will stop adding strontium.

What are the other similar pollutants I should not be adding to my tank?

[rshimek]

Hi,

I generally have figured that if you feed well, you need to add only the materials to maintain calcium and alkalinity. So... no molybdenum, trace metals, etc.

However, I am now analyzing some analytical chemical data from a study of numerous hobbyists (to be published here on RC next month). My analysis is yet incomplete, so I will not suggest any additional additives at this time, but I may well have to suggest some other materials to be added.

[chris_h]

This will save me some money . I will stop adding iodine and iron as well.

[JEMichael IV]

What about Plankton? Like DT's Plankton? That is the only thing that I add to my tank.

[rshimek]

Hi,

DT's is food, not an additive. Keep it coming.....

[Adrian]

I remember reading something about some hard corals using strontium in addition to calcium and some using only strontium for calcification, I think it was in TRA V.1, but Im not sure and don't have the time to search Im not arguing your point, you would know better than I, Im just curious, if Im not mistaken, aragonite is said to contain strontium and It would make sense to me that if aragonite contains it, it must have something to do with calcification

[rshimek]

Hi Adrian,

This is a long post, and for that I apologize, but there really is no short answer. Regarding the mistakes in TRA, see the second paragraph below and remember that the authors did no research on their own, they simply scanned the scientific literature, and they did that poorly.

First, the only organisms that I know of with a demonstrated physiological need for strontium are 1) early larvae of Aplysia, 2) early larvae of Octopus, and Acantharean Radiolarians which have a skeletacal capsule of strontium sulfate. There has been no demonstrated need for strontium in corals, indeed, just the opposite has been noted.

My reasons for considering Strontium a weak toxin are given below. There is no ambiguity for that conclusion. It is supported by several research papers all published in peer-reviewed professional journals. The only paper suggesting that strontium benefits corals is Swart’s 1980 paper, and it is this paper which is cited by Delbeek and Sprung as evidence that corals need strontium. Unfortunately, Delbeek and Sprung must have missed Swart’s 1981 paper where he explained that his 1980 conclusions were incorrect and based on incomplete research - the “publish or perish� syndrome strikes again. Delbeek and Sprung have also missed all of the other references on strontium and corals.... Good literature researchers, these guys ain’t...

There are a lot of papers investigating the concentration of strontium in coral skeletons. Without exception, these papers were looking at the relative amount of strontium as related to calcium as an indicator of temperature. If this could be done, then paleontologists could use the Sr/Ca ratio in fossil corals to determine the temperature of ancient seas. Unfortunately, after a lot research, it has become evident that this ratio is simply too variable to be of much use.

Relatively few papers have looked at Strontium metabolism in corals. Only one research paper, by a fellow named Swart, published in 1980 has shown any beneficial attributes of strontium.

Swart’s 1980 study indicated that strontium supplementation enhanced skeletal formation. He added large amounts of several chemicals, including strontium and calcium, to sea water elevating their relative ionic concentrations significantly above those found in normal sea water. When he added enough strontium to raise the strontium concentrations by a factor of 10, from 7 ppm to 77 ppm, he found that this massive addition of strontium caused a significant increase in skeletal growth. Interestingly, he found an identical increase with the addition of calcium.

The results presented in Swart’s 1980 paper indicate that strontium stimulates the formation of coral skeletons. Unfortunately, such a conclusion would be in error. These data were published prematurely (and Swart admitted as such), and were from the initial phase of a longer study. In the final results, Swart(1981), noted that increases in three factors: total strontium concentrations, strontium/calcium ratios, and increased calcium concentrations, ALL caused a growth increase. Additionally, there was a concentration level (approximately 100 ppm above the local �normal� sea water concentrations, or about 520 ppm) above which further increases in calcium concentration ceased to cause an increase in growth.

Here are the references - I suggest you read them.

Swart, P. K. 1980. The effect of seawater chemistry on the growth rates of some scleractinian corals. In: R. Tardent and P. Tardent (Editors). Developmental and Cellular Biology of Coelenterates. Proceedings of the Fourth International Coelenterate Symposium. Interlaken. pp. 203-208.

Swart, P. K. 1981. The strontium, magnesium and sodium composition of recent scleractinian coral skeletons as standards for paleoenvironmental analysis. Palaeogeogrraphy, Paleoclimatololy, Paleoecology. 34:115-136.

The results in these papers indicated that there appeared to be an unutilized potential for skeletal formation in natural seawater in the area of his studies. (Calcium concentration varies more than a little bit throughout oceanic waters) If additional ions of a chemically suitable nature are present, either calcium or strontium, the coral will use them to form the skeleton. The increases in the growth seen with the increases in strontium concentrations appear to be due to the substitution of strontium for the �missing� calcium.

Swart’s work indicated that either calcium or strontium will cause increases in skeletal growth provided the total of both ions is less than or equal to about 100 ppm above normal, or a total of 520 ppm. It is important to note that in the results from this study, strontium did not stimulate additional skeletal formation, it simply substituted for �missing� calcium ions. What was necessary was an ion of the right size and shape. In effect, strontium was an acceptable substitute for an unrealized calcium potential. It is also clear, however, is that apparently equivalent increased skeletal growth can be obtained by simply increasing calcium levels.

An examination of the scientific literature subsequent to Swart’s work shows that there is NO other evidence for any beneficial effects of strontium by itself to the corals.

Swart also stated the skeleton formed in the solutions containing higher than normal concentrations of strontium show decreased calcification (Swart, 1981), which he thought was simply due to the substitution of strontium for calcium. In fact, there is a small, but growing body of evidence that indicates that strontium REDUCES calcification rates in corals (Chalker, 1981; Swart, 1981; Ip and Krishnaveni, 1991; Wright and Marshall, 1991).

Here are those references - again, please read them.

Chalker, B. E. 1981. Skeletogenesis in scleractinian corals: the transport and deposition of strontium and calcium. In: Handbook of Stable Strontium. S.C. Skoryna (Ed.) Plenum Press. New York, pp. 47-63.

Ip, Y. K. and P. Krishnaveni. 1991. Incorporation of strontium (90Sr2+) into the skeleton of the hermatypic coral Galaxea fascicularis. Journal of Experimental Zoology. 258:273-276.

Wright, O. P. and A. T. Marshall. 1991. Calcium transport across the isolated oral epithelium of scleractinian corals. Coral Reefs. 10:37-40.

Wright and Marshall (1991) showed that strontium significantly reduced the transport of calcium ions across coral epithelial tissues. All calcium used by corals for either metabolic processes or for calcification comes from within the animal’s tissues, not directly from the sea water surrounding it. So, it has to pass through the epithelium. Thus a reduction in calcium transport into the animal will directly reduce all of these processes, including calcification. The presence of significant amounts of strontium could significantly inhibit and alter all calcium requiring processes, such as muscle contraction, tissue differentiations, growth, and injury repair) by reducing the calcium uptake from the surrounding waters.

Additional calcification reduction may be due to the substitution of strontium for calcium in the enzymatic pathways necessary for calcification. Strontium (and other doubly charged positive ions such as magnesium, barium and zinc) will occasionally substitute for calcium in the chemical processes that a coral uses for skeletogenesis. The substitution of strontium for calcium by corals, mollusks, and fishes appears accidental (Sadovy and Severin, 1992). However, strontium is not a twin of calcium and reacts somewhat differently than calcium, and may significantly slow down the calcification process. Thus, if the conditions are otherwise good for the corals, the addition of strontium would inhibit calcification. However, the deposition of strontium in the coral skeleton may not be due to simple substitution, see below.

Any strontium found in the coral skeleton is tightly bound into that skeleton. Such binding means that the chemical is not available to be utilized by, or influence the animal. Many invertebrate animals deposit wastes or toxins in crystalline matrices as a way of detoxifying their environment (Kozloff, 1990). It is possible that those corals whose skeletons contain relatively large amounts of strontium are selectively depositing it in the skeletons. This would remove that strontium from the metabolic pathways, as materials that are deposited as crystals are unavailable for biologically mediated reactions. In this way, any deleterious aspects of strontium ions in solution would countered. This type of elimination of “problem chemicals� is fairly common.

(See almost any issue of the journal, Marine Pollution Bulletin, for references to such pathways).

There is also some work indicating that strontium is rapidly and efficiently removed from the coral polyp and deposited into the skeleton (Ip and Krishnaveni 1991). They found that strontium was deposited into the skeleton of the coral Galaxea fascicularis by a pathway that appeared to be different from that used by the coral to deposit calcium. This pathway appeared to function when the calcification pathway was not working. This could indicate that natural selection has favored the development of an additional metabolic pathway to remove strontium from the solutions bathing the coral. Such a pathway would ameliorate any toxic effects due to this chemical, and would facilitate across membrane transport of calcium and subsequent skeletal calcification.

[Elendil]

Not that Ron needs any help here, but...

Regarding things like Strontium that could be harmful if misused, but nevertheless are present in sea water, there is an easy solution. Regular partial water changes! Bingman and Atkinson found their samples of Instant Ocean to contain roughly double the concentration of Sr that is found on average in sea water. So...if you're doing that 10% weekly water change, you're replenishing all you would need without the risk of overdosing or the cost of overpriced additives. (Now, I'm going with the assumption that Strontium is necessary at all, for those who still don't believe Ron or any of the published material. I personally don't give Sr a second thought, but if you're the hand-wringing type that says, "But what if there IS a secret use for Sr??? ," then you can just do the water changes and relax!

Ron also mentioned feeding as a source for trace elements. You can check out his study on food content here:
http://www.animalnetwork.com/fish/data/foods.asp
The food content reads like a who's who of trace elements in seawater.

The salt study mentioned above is here:
http://www.animalnetwork.com/fish2/a.../1/default.asp

It's comforting to know that with regular feeding and water changes I should never have a shortage of silver or titanium in my tank!

-Elendil

[SteveP]

I love threads like this! I find I can zip through aquarium supply catalogs a lot faster than only a year ago! "Don't need it, don't need it..." Thanks for taking the time to type that. If I may continue this...

What about dosing magnesium? I've read that adding it aids in the formation of coralline algae. Are the amounts we get from water changes sufficient?

Steve
8{I

[rshimek]

Hi Steve,

I will try to address this in my upcoming series of articles on "The Tank Water Study."

I don't think there are real good data to indicate that it is particularly necessary to supplement it beyond regular water changes. At high concentrations, it can interfere with calcium metabolism in a lot of inverts, but I doubt any dosing could get it to toxic levels.

I have not yet specifically looked at the study data for it. If you have good coralline growth without dosing, then I wouldn't do much with it. If you don't - and you want such - and you can test for it, then maybe it is worth while to dose it.

I think my standard dictum here is, "When in doubt, leave it out."

[SteveP]

Fair enough! Thanks, Doc.

Steve
8{I

[Adrian]

Very interesting, thanks Looking forward to the tank water study

[CTaylor]

I seem to have success with Kents Sr/Moly/K supp and elegans.

[Lutefisk]

Dr. Ron,

Thank you for your amazing effort at answering our questions so fully!

My grandmother might not have understood all that (and truth be told maybe I didn't either) but I learn a lot from you.

I hope this thread will be marked for the archives. I hate to think about you having to come up with all that information again.

Paul