Strontium Levels
- Thread starter SouthernR
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I used to not worry about it, but when my SPS load got high, I bought a Salifert test kit. To my surprise, it was low. I started dosing the Kent Turbo Strontium product mixed in with the calcium part of my peristalic pump-dosed 2-part. Been doing it for a bit over a year since I got rid of the CaRX. It has really stabilized things for me and something is definately consuming it in my tank and corals grow quite fast since I started the regieme.
THIS IS A ARTICLE ON DT'S WEB SITE THAT DENNIS TAGRIN SHOWED ME LAST WEEKEND THAT I THOUGHT WAS INTERESTING,
The Strange Case of Strontium
Strontium is an element that has a lot of affinities to both calcium and magnesium. In fact these three elements, magnesium, calcium, and strontium constitute a triplet, three sequential elements in column IIA, the alkali earth metals of the periodic table. The whole column is, in order, beryllium, magnesium, calcium, strontium, barium and radon. All of these elements form ions with a +2 valence, and all of them are somewhat “similar” chemically. Similar – but not identical… and therein lies the rub. Apparently while magnesium and calcium are beneficial for animals, the other elements of that group are not.
Figure 3. The "Periodic table (from Wikipedia, The Free Encyclopedia. 9 Jan 2007, 22:44 UTC. Wikimedia Foundation, Inc. 11 Jan 2007). The alkali earth metals, such as magnesium, calcium and strontium, are on the left in the orange column.
Nonetheless, there is a prevailing myth in the aquarium literature that one should add strontium to aquarium water to replace the strontium that is used up. And used up it is. So, it might seem reasonable that it should be added. Might seem – but, not if one looks at the scientific literature written over the last twenty or so years. The tale of strontium and corals constitutes one of the more fascinating stories in coral biochemistry.
The story starts about sixty years ago, shortly after the first American hydrogen bomb tests, which were done on Pacific atolls in the early 1950s. The thermonuclear reactions of such explosions transmuted some of the calcium in the vaporized atoll limestone into an isotope of strontium, strontium90. Strontium90 soon became important because, like all other strontium isotopes it behaves similar to calcium and in that regard it soon became apparent it was being deposited in human bones. It is also highly radioactive and quite dangerous. As a result of these two facts, the human usage and the radioactivity, a widespread program of testing for strontium in the natural world was initiated. One of the more interesting facts that came from this was the information that strontium, of all isotopes, was deposited in small amounts in coral skeletons. The second fact of interest was that this deposition of strontium in coral skeletons was related to temperature, so there was a minor, but widespread, survey of corals and fossil corals to measure the amount of strontium. In this way, it became possible for paleontologists to estimate the temperature of ancient seas. If the strontium was being deposited the same way in ancient times as it was being deposited today, and if there was a temperature relationship, then one could assume what happened then was similar to what was happening now and make a guess as to the ancient seas’ temperatures.
Well, the tale wasn’t as simple as it first appeared. It was presumed that strontium being just slightly larger than calcium was being used in chemical reactions, “by happenstance” or mistake, at about the relative proportional abundance of strontium to calcium. That was the state of the art in the early 1980s. In the late 1970s, a student working at a site in the Great Barrier Reef did an experiment where he incubated corals with an excess of strontium in solution. By golly, he got good, and extra, coral growth in the skeleton. And he published this in 1980 (Swart, 1980). The conclusion was that extra strontium in solution boosted coral growth. A few years later this was noticed by some coral reef aquarists and they incorporated that information into some publications (Delbeek, and Sprung, 1994).
Unfortunately, what those reef aquarium authors didn’t do was read the next article that the initial researcher wrote (Swart, 1981). Here he explained that his first conclusion was an error. What had happened was that in the region where he did his research, the sea water concentration of calcium was only about 310 ppm, and any material similar to calcium - including – Golly, Gee, Surprise, Calcium itself, added to the sea water would increase the growth of corals. So the data saying that strontium was causing extra growth in corals was in error. What was happening was that anything like calcium (including calcium, magnesium and strontium) added to the sea water of that area would increase coral growth, up to a maximum level of about 525 ppm, after which the increase in growth ceased. Of course our stalwart aquarium authors (Delbeek, and Sprung. 1994) never bothered to get the message…
But, as they say, “That ain’t all…”
Other researchers, more interested in how strontium was added to the coral skeleton, found some very neat things. They found that strontium is incorporated into the coral skeleton differently than is calcium. It doesn’t simply replace calcium in the aragonite crystal lattice (Chalker, 1981; Ip, and Krishnaveni. 1991). This means that there is a special biochemical process or pathway in corals to ensure that strontium is put into the coral skeleton.
The question any scientist – and aquarist – interesting in strontium should ask themselves is, “Why is strontium deposited differently than is calcium?” The answer to that question was found by two other researchers (Wright and Marshall, 1991). These scientists found that strontium inhibits or “poisons” calcium ion transport across coral epithelial tissues. This very important and bears repeating:
“Strontium “poisons” calcium ion transport across coral epithelial tissues.”
Why is this important? The answer is that calcium is very important to corals. One might think that it is most important in that it goes to form the skeleton, but that is probably a secondary issue. What is more important is that calcium is used and found in high concentration in the nematocysts that corals use to catch their food. Additionally, calcium is important in the relaxation and resetting of the coral animal’s muscles. Once the muscle contracts, unless there is an excess of calcium ion in the coral’s epithelium, that muscle cannot relax and reset itself to contract again and the animal can’t move.
The final piece to this puzzle of strontium is that strontium is deposited in coral skeletons as a specialized mineral called Strontianite (Greegor, et al. 1997).
The whole strontium story with regard to corals is that strontium is a weak poison, inhibiting the transfer of calcium into the coral’s tissues and thus affecting all of the biology of the coral. Because of this, natural selection has favored a process to remove strontium from its tissues. The way in which the coral does this is by specifically depositing strontium as a special mineral in small clusters in its skeleton. Once the strontium is precipitated as a mineral it is out of solution and no longer a threat to the coral’s metabolism. Ideally, for a coral, its sea water would not have an excess of strontium, but it would strontium-free.
Consequently, it is to the advantage of a reef aquarist to NEVER add any material containing strontium to their system.
And, of course, most stalwart aquarium authors never bother to get the message…
Iodine
Like strontium, iodine is another element where a decidedly “odd” aquarium
The Strange Case of Strontium
Figure 3. The "Periodic table (from Wikipedia, The Free Encyclopedia. 9 Jan 2007, 22:44 UTC. Wikimedia Foundation, Inc. 11 Jan 2007). The alkali earth metals, such as magnesium, calcium and strontium, are on the left in the orange column.
Nonetheless, there is a prevailing myth in the aquarium literature that one should add strontium to aquarium water to replace the strontium that is used up. And used up it is. So, it might seem reasonable that it should be added. Might seem – but, not if one looks at the scientific literature written over the last twenty or so years. The tale of strontium and corals constitutes one of the more fascinating stories in coral biochemistry.
The story starts about sixty years ago, shortly after the first American hydrogen bomb tests, which were done on Pacific atolls in the early 1950s. The thermonuclear reactions of such explosions transmuted some of the calcium in the vaporized atoll limestone into an isotope of strontium, strontium90. Strontium90 soon became important because, like all other strontium isotopes it behaves similar to calcium and in that regard it soon became apparent it was being deposited in human bones. It is also highly radioactive and quite dangerous. As a result of these two facts, the human usage and the radioactivity, a widespread program of testing for strontium in the natural world was initiated. One of the more interesting facts that came from this was the information that strontium, of all isotopes, was deposited in small amounts in coral skeletons. The second fact of interest was that this deposition of strontium in coral skeletons was related to temperature, so there was a minor, but widespread, survey of corals and fossil corals to measure the amount of strontium. In this way, it became possible for paleontologists to estimate the temperature of ancient seas. If the strontium was being deposited the same way in ancient times as it was being deposited today, and if there was a temperature relationship, then one could assume what happened then was similar to what was happening now and make a guess as to the ancient seas’ temperatures.
Well, the tale wasn’t as simple as it first appeared. It was presumed that strontium being just slightly larger than calcium was being used in chemical reactions, “by happenstance” or mistake, at about the relative proportional abundance of strontium to calcium. That was the state of the art in the early 1980s. In the late 1970s, a student working at a site in the Great Barrier Reef did an experiment where he incubated corals with an excess of strontium in solution. By golly, he got good, and extra, coral growth in the skeleton. And he published this in 1980 (Swart, 1980). The conclusion was that extra strontium in solution boosted coral growth. A few years later this was noticed by some coral reef aquarists and they incorporated that information into some publications (Delbeek, and Sprung, 1994).
Unfortunately, what those reef aquarium authors didn’t do was read the next article that the initial researcher wrote (Swart, 1981). Here he explained that his first conclusion was an error. What had happened was that in the region where he did his research, the sea water concentration of calcium was only about 310 ppm, and any material similar to calcium - including – Golly, Gee, Surprise, Calcium itself, added to the sea water would increase the growth of corals. So the data saying that strontium was causing extra growth in corals was in error. What was happening was that anything like calcium (including calcium, magnesium and strontium) added to the sea water of that area would increase coral growth, up to a maximum level of about 525 ppm, after which the increase in growth ceased. Of course our stalwart aquarium authors (Delbeek, and Sprung. 1994) never bothered to get the message…
But, as they say, “That ain’t all…”
Other researchers, more interested in how strontium was added to the coral skeleton, found some very neat things. They found that strontium is incorporated into the coral skeleton differently than is calcium. It doesn’t simply replace calcium in the aragonite crystal lattice (Chalker, 1981; Ip, and Krishnaveni. 1991). This means that there is a special biochemical process or pathway in corals to ensure that strontium is put into the coral skeleton.
The question any scientist – and aquarist – interesting in strontium should ask themselves is, “Why is strontium deposited differently than is calcium?” The answer to that question was found by two other researchers (Wright and Marshall, 1991). These scientists found that strontium inhibits or “poisons” calcium ion transport across coral epithelial tissues. This very important and bears repeating:
The final piece to this puzzle of strontium is that strontium is deposited in coral skeletons as a specialized mineral called Strontianite (Greegor, et al. 1997).
The whole strontium story with regard to corals is that strontium is a weak poison, inhibiting the transfer of calcium into the coral’s tissues and thus affecting all of the biology of the coral. Because of this, natural selection has favored a process to remove strontium from its tissues. The way in which the coral does this is by specifically depositing strontium as a special mineral in small clusters in its skeleton. Once the strontium is precipitated as a mineral it is out of solution and no longer a threat to the coral’s metabolism. Ideally, for a coral, its sea water would not have an excess of strontium, but it would strontium-free.
Consequently, it is to the advantage of a reef aquarist to NEVER add any material containing strontium to their system.
And, of course, most stalwart aquarium authors never bother to get the message…
Iodine
Yes, Ill Do That Right Quick
Iodine
Like strontium, iodine is another element where a decidedly “odd” aquarium mythology has developed in the last couple of decades. Iodine is a chemical that is found in a number of marine organisms. Most of these, are algae, and in fact most are brown algae (phaeophytes) such as kelp that are never found in aquaria. Vertebrates also require iodine to produce thyroid hormone. Primitive chordates such as tunicates as require iodine, in their case for the production of the mucus they use to capture the plankton they feed up. That mucus, by-the-way, is 9-hydroxythryonine – or human thyroid hormone, indicating a close and similar evolutionary relationship between politicians and sea squirts, those rather amorphous blobs that sit on the bottom of the ocean and feed on dissolved waste; I guess, that fits…
Some other animals do appear to accumulate iodine, probably as a defensive chemical, as iodine containing compounds are often unpalatable or toxic. Because iodine is present in many algae that are used in the manufacture of marine aquarium foods, the amount of iodine in most marine aquarium foods is very high, and as a result in most tanks the concentration is probably excessive, well above natural levels (Shimek, 2002).
Figure 4. Phaeophytes, such as this huge kelp, Macrocystis integrifolia, which reaches lengths of more 30 m, sequester iodine containing compounds, primarily as anti-predator defensive chemicals (Boney, 1966).
Iodine, per se, will never be found in marine aquaria or marine systems as it is rapidly oxidized to iodate. Additionally, iodine is capable of forming numerous organo-iodine compounds of varying toxicity. This creates a significant problem for aquarists; it is essentially impossible to ascertain the amount of iodine found in a marine aquarium. Given the toxicity of many of the various iodine containing materials, I do not recommend supplementing iodine to any marine tank. And no, Xenia doesn’t need iodine.
Trace Elements
The measurement of trace elements in marine waters is exceptionally difficult. As Pilson, 1998, states (with my emphasis, in red, added),
“We may conclude that data on the concentrations of trace substances in seawater should be taken with a grain of salt (so to speak) unless there is very good reason to believe them. Perhaps no trace element data may be considered entirely trustworthy until the methods and data have been duplicated in more than one laboratory. ... The real concentrations are so vanishingly small that the quantities present are easily swamped by contamination. An undertaking to make such measurements involves much planning and attention to detail, and is not to be entered into lightly. The difficulty involved means that only a limited number of laboratories will be in a position to make such measurements routinely.”
Suffice it to say, no aquarist will ever be able to reliably test any trace metal concentration in their tank. It is also likely, that no manufacturer of salts or additives will be able to reliably test their own materials for these elements.
Additionally, all of the trace elements are toxic to animal life at levels that barely exceed their natural levels. As with iodine, they tend to be concentrated as they pass up the food chain, so in the manufacture of foods using marine animals and plants, they are often rather highly concentrated. Really the problem in aquaria is not supplementing trace materials but removing them. They are toxic to most animals in very low amounts, yet interesting they are required by many of the algae. This is one of the pieces of evidence used to indicate the evolutionary “distance” between animals and algae. While many of us tend to think that “life is life is life;” the differences between some life forms are often extreme, and the biochemical differences between these algae and animals show this very well. What these algal organisms require for nutrients will kill many animals (See for example: Carey, 1981; Heyward, 1988; .Goh and Chou, 1992; Sadovy, and Severin. 1992; Rumbold and Snedaker. 1997; Reichelt-Brushett and Harrison. 1999; Breitberg, et al., 1999; Alutoin, et al., 2001; Negri and Heyward, 2001; Velasquez, et al., 2002; Morel and Price. 2003; Hintz, et al., 2004).
NEVER
– EVER –
SUPPLEMENT TRACE METALS!
Some other animals do appear to accumulate iodine, probably as a defensive chemical, as iodine containing compounds are often unpalatable or toxic. Because iodine is present in many algae that are used in the manufacture of marine aquarium foods, the amount of iodine in most marine aquarium foods is very high, and as a result in most tanks the concentration is probably excessive, well above natural levels (Shimek, 2002).
Figure 4. Phaeophytes, such as this huge kelp, Macrocystis integrifolia, which reaches lengths of more 30 m, sequester iodine containing compounds, primarily as anti-predator defensive chemicals (Boney, 1966).
Iodine, per se, will never be found in marine aquaria or marine systems as it is rapidly oxidized to iodate. Additionally, iodine is capable of forming numerous organo-iodine compounds of varying toxicity. This creates a significant problem for aquarists; it is essentially impossible to ascertain the amount of iodine found in a marine aquarium. Given the toxicity of many of the various iodine containing materials, I do not recommend supplementing iodine to any marine tank. And no, Xenia doesn’t need iodine.
Trace Elements
“We may conclude that data on the concentrations of trace substances in seawater should be taken with a grain of salt (so to speak) unless there is very good reason to believe them. Perhaps no trace element data may be considered entirely trustworthy until the methods and data have been duplicated in more than one laboratory. ... The real concentrations are so vanishingly small that the quantities present are easily swamped by contamination. An undertaking to make such measurements involves much planning and attention to detail, and is not to be entered into lightly. The difficulty involved means that only a limited number of laboratories will be in a position to make such measurements routinely.”
Suffice it to say, no aquarist will ever be able to reliably test any trace metal concentration in their tank. It is also likely, that no manufacturer of salts or additives will be able to reliably test their own materials for these elements.
Additionally, all of the trace elements are toxic to animal life at levels that barely exceed their natural levels. As with iodine, they tend to be concentrated as they pass up the food chain, so in the manufacture of foods using marine animals and plants, they are often rather highly concentrated. Really the problem in aquaria is not supplementing trace materials but removing them. They are toxic to most animals in very low amounts, yet interesting they are required by many of the algae. This is one of the pieces of evidence used to indicate the evolutionary “distance” between animals and algae. While many of us tend to think that “life is life is life;” the differences between some life forms are often extreme, and the biochemical differences between these algae and animals show this very well. What these algal organisms require for nutrients will kill many animals (See for example: Carey, 1981; Heyward, 1988; .Goh and Chou, 1992; Sadovy, and Severin. 1992; Rumbold and Snedaker. 1997; Reichelt-Brushett and Harrison. 1999; Breitberg, et al., 1999; Alutoin, et al., 2001; Negri and Heyward, 2001; Velasquez, et al., 2002; Morel and Price. 2003; Hintz, et al., 2004).
NEVER
– EVER –
SUPPLEMENT TRACE METALS!
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