MOJO !!!Read this: Influence of seawater Sr content on coral Sr/Ca and Sr thermometry

[Boomer]

Influence of seawater Sr content on coral Sr/Ca and Sr thermometry

Y. Sun1, M. Sun , T. Lee and B. Nie, Coral Reefs, DOI: 10.1007/s00338-004-0467-x, 25 January 2005

Abstract The Ca content of a Porites coral from Xisha, South China Sea is quite uniform along its 18-year growth axis. A comparison with previously published data shows that the Ca content of corals from different sites varies by only 0.4%. This is much smaller than the variation of Ca in seawater (2.2%), indicating that Ca variations in seawater do not significantly affect the Ca compositions of coral skeletons. The variation in skeletal Ca contents results in only ±0.6°C of uncertainty in SST calculations, which is much smaller than the large disparities observed for previously established coral Sr/Ca thermometers. In contrast, Sr in tropical seawater varies spatially by as much as 2.4%, corresponding to ~4°C offset for coral Sr/Ca calibrations. The effect of seawater Sr variations on coral Sr/Ca thermometers is evaluated and we demonstrate that the content of seawater Sr is the major factor responsible for disparities in these coral Sr/Ca thermometers. The disparities can be significantly reduced when seawater Sr contents are included in the Sr/Ca thermometers.

 

[Maxx]

Boomer,
i'm a little confused...this is stating that Sr levels are more influential in Porites Ca uptake, than the calcium levels in the surrounding water?
Or did I interperet that wrong?

Nick

 

[Boomer]

No

Old reports use to be to be based on temp alone for the change in the Sr/Ca ratios, as shifts in water temp change things and can thus be used as paleo-indicators. In the last few years this has shown to be mostly false, that it is mostly the Sr concentraion that causes this shift in the Sr/Ca ratio. It has been my theroy for 20 years, in that it is the Sr and to some extent the Ba that may cuase shifts in allometric growth rate of hard corals. But this report hasn't mentioned if that, allometrics, is taking place or not, so I'm half way there

 

[Boomer]

Wake up Mojo

 

[mojoreef]

Boomer wasnt that to do with zoox in the corals?? That photosynthesis by the algae decreases the relative uptake of strontium by the coral. Going by memory but wasnt thier a recent study done that showed that thier temp/SR thing was actually controled by zoox. Corals with zoox didnt uptake Sr. anywhere close to corals with out, regardless of temp??

I will go take a peek


Mike

 

[mojoreef]

Ok how about this one

The strontium-to-calcium ratio (Sr/Ca) of reef coral skeleton is commonly used as a paleothermometer to estimate sea surface temperatures (SSTs) at crucial times in Earthís climate history. However, these estimates are disputed because uptake of Sr into coral skeleton is thought to be affected by algal symbionts (zooxanthellae) living in the host tissue. Here, we show that significant distortion of the Sr/Ca temperature record in coral skeleton occurs in the presence of algal symbionts. Seasonally resolved Sr/Ca in coral without symbionts reflects local SSTs with a temperature sensitivity equivalent to laboratory aragonite precipitated at equilibrium, and the nighttime skeletal deposits of symbiotic reef corals. However, up to 65% of the Sr/Ca variability in symbiotic skeleton is related to symbiont activity and does not reflect water temperature.

or this one

Modeling of past climates is critically dependent on estimates of past sea surface temperatures (SSTs) for which one of the principal techniques used is the measurement of Sr/Ca ratios in corals (Guilderson et al. 1994, McCulloch et al., 1999; Hughen et al., 1999). The link between coral Sr/Ca and SST is not well understood and there have beena number of descrepant observations (de Villiers et al., 1995; Alivert, 1998). Corals with symbiotic zooxanthellae are known to show large diurnal fluctuations in calcification rate associated with the photosynthetic activity of their symbionts. Using detailed measurements with the ion microprobe, we compared the Sr/Ca content of discrete daytime and nighttime skeletal structures in the massive hermatypic coral Porites lutea over the course of 1 year and a seasonal temperature range of 4æC. The Sr/Ca content of daytime skeleton is always lower thatn that of adjacent nighttime skeleton. While the slope of the nighttime Sr/Ca-SST correlation is close to that seen in inorganic aragonite precipitates, that of the daytime correlation is>4 times as steep. We attribute these differences to the role of photosynthesis in calcification and conclude that bulk Sr/Ca is related principally to daytime calcification rate rather than directly to SST. More reliable estimates of past SST may be arrived at through selective analysis of nighttime skeleton.

Calcification by corals with symbiotic zooxanthellae occurs 3 times faster in daylight than it does at night. We investigated the effects of light enhanced calcification on the microstructure and elemental chemistry of the aragonite skeleton over the diurnal cycle. The morphology of nighttime crystals accreted in the absence of photosynthesis imitates that of slow growing inorganic cements in a high CO2 environment. The morphology of daytime crystals accreted during the photosynthetic period imitates that of fast growing inorganic cements in a low CO2 environment. We used an Cameca IMS 3f ion microprobe to measure changes in the strontium-calcium content (Sr/Ca) of the growing skeleton of the tropical reef coral, Porites lutea, over the diurnal cycle. Sr/Ca in nighttime skeleton is close to equilibrium values but a large decrease in Sr/Ca is observed as the daytime crystals grow to fill the extracellular calcifying space in summer. The amplitude of change in skeletal Sr/Ca between night and day is as large as the annual cycle in Sr/Ca. During summer, at peak water temperature and symbiont photosynthesis, the amplitude of the diurnal Sr/Ca cycle is 3 times greater than that incurred only by the diurnal change in water temperature. During winter, the amplitude of the diurnal Sr/Ca cycle is equivalent to that incurred by temperature alone. Our data show that processes linked to symbiont photosynthesis exert significant influence on both skeletal microstructure and microchemistry, and that temperature is not the primary control of diurnal Sr/Ca variability in reef coral skeleton

and one last study

The strontium/calcium ratio (Sr/Ca) of reef coral skeleton is used as a paleothermometer to estimate sea surface temperatures (SSTs) at crucial times in the earths’ climate history. However, these estimates are disputed because uptake of Sr into coral skeleton is thought to be affected by algal symbionts (zooxanthellae) living in the host tissue. Here we show for the first time that significant distortion of the Sr/Ca temperature record in coral skeleton occurs in the presence of algal symbionts. Microscale measurements of skeletal Sr/Ca in co-occuring symbiotic and asymbiotic colonies of Astrangia poculata were made using SIMS ion microprobe. Seasonally-resolved Sr/Ca in asymbiotic skeleton reflects local SSTs with a temperature sensitivity equivalent to laboratory aragonite precipitated at equilibrium, and the nighttime skeletal deposits of symbiotic reef corals. However, up to 65% of the Sr/Ca variability in symbiotic skeleton is related to the symbiosis and does not reflect water temperature. Our data indicate that Sr/Ca in asymbiotic species and nighttime accretions of tropical reef corals should be targeted for accurate estimates of past SSTs.

mike

 

[Boomer]

Boomer wasnt that to do with zoox in the corals??

Yes, that is correct, I don't dispute that. The issue is you can't use temp as a paleo-indicator when dealing with Sr/Ca ratios or lets say those with Zoo's, where in the past it always was. These abstracts also say this.

However, up to 65% of the Sr/Ca variability in symbiotic skeleton is related to symbiont activity and does not reflect water temperature.

and that temperature is not the primary control of diurnal Sr/Ca variability in reef coral skeleton


I wanted you to see this;

that Ca variations in seawater do not significantly affect the Ca compositions of coral skeletons


wasnt thier a recent study

Just fo to Google's and type in;

Sr/Ca thermometers

 

[mojoreef]

that Ca variations in seawater do not significantly affect the Ca compositions of coral skeletons

Well who didnt know that!!! You got to think bisphosphonate chelating agents!!


MIke

 

[Boomer]

Sr and Li have more of an effect than any bisphosphonate chelating agent

 

[mojoreef]

Do you have something on the Li??


Mike

 

[Maxx]

Guys,
hate to ask for the "Chemistry for Dummies" version.....but what are bisphosphonate chelating agents? And what role do they play in calcium uptake by corals?

 

[NaH2O]

but what are bisphosphonate chelating agents?

Something that caused me stress in chem at Purdue. If I remember right - a chelating agent is a compound that can bond with metal ions??? oh boy - am I taking a chance there.

I need the "Chemistry for Airheads" version of why it was thought temperature played a roll? Remember....you are dealing with a female here.....I may be level Yellow to Orange on the Homelife Security Alert levels.

 

[Boomer]

Mojo

No, and I meant Ba but Li is there also. I can not find for the life of me my old ref on them. Randy and Habib asked the same thing. I found them years ago when doing research for Thiel. The only thing I really remember is the Barium. A guy had some photo's under special light, that kinda made the Ba Fluorescent. The highest concentrations where always at the newest tips.

Nikki

version of why it was thought temperature played a roll?

Solution kinetics and how it relates to temp. As temp changes some ions precip more than others. You should find allot of this on Forams An old geology paleo-indicator are the ratios of oxygen isotopes found in glacial ice.

Maxx and Nikki

This will help

Corals and bisphosphonate chelating agents

Look under " Discussion", 4th paragraph at the bottom
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=59737

http://jeb.biologists.org/cgi/content/abstract/205/14/2107

http://www.advancedaquarist.com/issues/apr2002/chem.htm


diphosphonate (di·phos·pho·nate) (di-fos¢f[schwa]-n[amacr]t) 1. a salt, ester, or anion of diphosphonic acid. While structurally similar to pyrophosphate, its P—C—P bonds give it enhanced stability to enzymatic and chemical hydrolysis. 2. any of a group of such compounds, having affinity for sites of osteoid mineralization and used as sodium salts to inhibit bone resorption as well as complexed with technetium Tc 99m for bone imaging; including alendronate, clodronate, etidronate, and pamidronate. Called also ***bisphosphonate***.


In pharmacology, bisphosphonates (also called: diphosphonates) is a class of drugs that inhibits the resorption of bone. Its uses are the prevention and treatment of osteoporosis, osteitis deformans ("Paget's disease of bone"), bone metastasis (with or without hypercalcemia) and other conditions that feature bone fragility.

Mojo is really stretching the issue of biophosphonate as a Ca inhibitor. "Tests" have shown it does, when given to them. It is not like it is floating around in the water in large amounts or they produce it A

 

[mojoreef]

Mojo is really stretching the issue of biophosphonate as a Ca inhibitor. "Tests" have shown it does, when given to them. It is not like it is floating around in the water in large amounts or they produce it A

Its a biproduct of ALP (alkaline phosphatase). As in the ALP hydrolyzes it.




mike

 

[Boomer]

Yes, but there is little evidence showing it is actually doing that, inhibiting coral growth, other than tests where the researcher is increasing or decreasing the amount to see what effect it has on them. I have yet to see a paper, where the coral is increasing the levels to a point where it inhibits coral growth. Got one

You said You got to think bisphosphonate chelating agents!!

Why should I think that ! Also there are is bisphosphonate and bisphosphonate chelating agents. Do you know the difference

 

[cwcross]

Well, this is common. Words like bi-phosphonate can be thrown around somewhat indescriminately. I sell about a million lbs a year of a proprietary isobutylene based bi-phosphonate thio-ester. It doesn't chelate worth a damn but it is a great high temperature dispersant for a jet turbines fuel system. We have to add proprietary di-amines to provide metal de-activation...or chelation for the formulation to prevent catalyzed combustion by-products from occuring. The chemistry and physics of phosphonates are very diverse to say the least.

 

[mojoreef]

I have yet to see a paper, where the coral is increasing the levels to a point where it inhibits coral growth. Got one

yea but I got to scan it
Yamashiro, H. (1995) J. Exp. Mar. Biol. Ecol. 191, 57-63.

Also there are is bisphosphonate and bisphosphonate chelating agents. Do you know the difference

Oh yea now we going to have skill testing questions are we
bisphosphonate is a group of PO3 linked to carbon and the other ..well....is a chelating agent, or did I have to give the definition of that??


Mike

 

[mojoreef]

Well, this is common. Words like bi-phosphonate can be thrown around somewhat indescriminately

Not sure what you mean here Collin?


Mike

 

[Boomer]

Oh yea now we going to have skill testing questions are we

Yes, and here is your first test

The Journal of Experimental Biology 205, 2107-2113 (2002)

Effect of increased calcium concentration in sea water on calcification and photosynthesis in the scleractinian coral Galaxea fascicularis

Alan T. Marshall* and Peta L. Clode (2002)

The relationship between calcification and photosynthesis in coral was investigated using standard sea water with enhanced calcium concentration. In standard sea water at 23°C with the calcium concentration increased by 2.5 mmol l-1, incorporation of calcium into the skeleton increased by 30-61 %, depending on the method of data normalisation, and photosynthesis, measured as 14C incorporation into the tissues, also increased by 87 %. At 29 °C, calcium incorporation into the skeleton increased by 54-84 % and 14C incorporation increased by 32 % when sea water calcium concentration was increased by 5 mmol l-1. However, photosynthesis measured as net photosynthetic oxygen production did not increase. Similarly there was no change in respiration rate when coral polyps were incubated in high-calcium sea water. It is conjectured that an increase in photorespiration may be responsible for the latter observations. ***Bisphosphonate has been considered to inhibit calcification*** but not photosynthesis in corals. We show that bisphosphonate may not inhibit formation of amorphous calcium carbonate and that the inhibition of calcification is possibly illusory. The data are consistent with the trans-calcification model, which suggests that calcification is a source of CO2 for photosynthesis in corals.


Full Text
http://jeb.biologists.org/cgi/content/full/205/14/2107

Yamashiro, H. (1995) J. Exp. Mar. Biol. Ecol. 191, 57-63

I know about that paper, it is the same one everybody cites. Randy has it in his article I posted It is the only one there is. The above abstract also cites it.

In short his paper says this;;

In coral, ALP ***might*** hydrolyze phosphate inhibitors of calcification, such as bisphosphonate chelating agents, which have been shown in vivo to inhibit calcification of hard coral Stylophora pistillata.Yamashiro, laced his subject coral correct ?

Another subject you should really like this one.

Interactions between zooplankton feeding, photosynthesis and skeletal growth in the scleractinian coral Stylophora pistillata

http://jeb.biologists.org/cgi/content/full/207/9/1461

 

[cwcross]

Not sure what you mean here Collin?


Mike

Well, I'm not saying you are doing this. However, it is something I see a lot in both reef chemistry as well as other areas I deal with.

Bi-Phosponates is a generic term that is used to discribe a very large group of compounds with diverse physical and chemical properties.

One always needs to be careful not to overgeneralize. This speaks to the point Boomer made regarding the difference between bi-phosponates and bi-phosphonate chelating agents. Just because a compound can be discribed as a bi-phosphonate implies in no way that it can chelate or have any other sort of intrisic and extrinsic property.

Kind of like saying that a chicken can't fly..a chicken is a bird...so birds can't fly. Urban myth's or industry wide myths are often propogated this way.

For what its worth...Collin