magnesium important to chlorophyl?

boxfishpooalot

boxfishpooalot

Active member
Quote from saliferts web page under magnesium test kit:

"
Magnesium is present in NSW in a fairly high concentration (1300 - 1400 mg/L). Magnesium is an essential part of chlorophyll, which is necessary for photosynthesis. Without photosynthesis plants, including algae and the corals, which we usually have in our aquariums, would not be able to live."

Huh?How is magnesium nescessary to chlorophyl? What are they using it for, and do they reduce it? :)
 
Thanks, Joanthan. :)

While it is an important part of many biomolecules, magnesium is present in such high concentrations in seawater that this mechanism is unlikely to deplete it (unlike calcification which can). However, does it become a complication at very low magnesium levels? Maybe. It is potentially another reason to maintain natural levels of magnesium. :)
 
Well that's a very interesting question: at what concentration does Mg limit marine algae. Since it's so abundant they've no reason to be particularly good at sucking it up, but then again one would have to really deplete it to get it to what would seem like a "low" level.
 
When I started my latest reef tank I had a dozen or so mangroves in my stock tank sump. I though it looked pretty neat. Then I read a composition breakdown and found they really didn't have the nutrient absorption levels of the macro's like chaeto. (time vs. weight increase etc.)

But anyway, my magnesium seemed to be dropping like a rock constantly. They were growing great and even faster than what I had read from others. I believe this to be from the regulation of osmotic pressures since they are naturally a brackish plant. I believe this to is consistant with the chemical breakdown done on them as well. IIRC
 
Why?

The magneisum content inside of cells may be lower than in seawater, just as is sodium and chloride.

For example:

Salt and water balance in two marine spider crabs, Libinia emarginata and Pugettia producta. I. Urine production and magnesium regulation. Cornell, John C. Dep. Zool., Univ. California, Berkeley, CA, USA. Biological Bulletin (Woods Hole, MA, United States) (1979), 157(2), 221-33.

Abstract

A new technique for continuous collection of crab urine was used to est. urine prodn. Intermolt P. producta (av. wt. 101 g) in seawater produced urine at 6.4% body wt./day. Premolt and postmolt crabs (65 and 73 g, resp.) produced urine at 29.5 and 2.89% body wt./day. Intermolt L. emarginata produced urine at 5.1% body wt./day. The Pugettia urine prodn. rate estd. by wt. gain following 24 h of nephropore occlusion was 2.95%, which was less than that detd. by the continuous collection of urine. Thus, back pressure could interfere with urine prodn. When expressed as a percentage of their concns. in seawater, Pugettia blood plasma concns. of Cl-, Na+,Mg2+, Ca2+, and K+ were 98.0, 97.8, 88.3, 118, and 105%, resp., for crabs in seawater. Similarly in urine, the values for these same ions were 99.4, 96.1, 135, 124, and 114%, resp. Ninhydrin-pos. substances, measured with glycine stds., were 3.72 and 0.39 mM in Pugettia blood plasma and urine, resp. The elec. potential across the body wall of P. producta and L. emarginata was zero. In Pugettia, blocking the nephropores increased Mg2+ concn. in the blood, suggesting that the excretory system is mainly responsible for regulating Mg2+. However, nephropore blocking did not change the Mg2+ concn. of urine stored in the bladder, suggesting that the antennal gland is mainly responsible for concg. Mg2+ in the urine.
 
Im assuming osmosis of plants would replace the bladder(urine) example of crabs. So osmotic pressure differences would be forcing magnesium into the plant, while the plant would spend time keeping it out? Plants must have low magnesium for this to be true, or lower than nsw anyway.

Not to be rude, but how does crabs relate to plants in this situation? Is osmosis the driving force? :D
 
I would assume plants and animals have similar internal salt concentrations, and that was the basis for my comment. I've not seen actual data to comment for algae.
 
Re: magnesium important to chlorophyl?

<a href=showthread.php?s=&postid=6827909#post6827909 target=_blank>Originally posted</a> by boxfishpooalot
Quote from saliferts web page under magnesium test kit:

"
Magnesium is present in NSW in a fairly high concentration (1300 - 1400 mg/L). Magnesium is an essential part of chlorophyll, which is necessary for photosynthesis. Without photosynthesis plants, including algae and the corals, which we usually have in our aquariums, would not be able to live."

Huh?How is magnesium nescessary to chlorophyl? What are they using it for, and do they reduce it? :)
Click to expand...


I will reproduce the whole section shortly and that will (I hope :D) put it in a slightly different context.

It doesn't imply (at least that was not the intention) that low Mg concentration would reduce the rate of photosynthesis. :)



OK here is the full text:


"Magnesium is present in NSW in a fairly high concentration (1300 - 1400 mg/L). Magnesium is an essential part of chlorophyll, which is necessary for photosynthesis. Without photosynthesis plants, including algae and the corals, which we usually have in our aquariums, would not be able to live.



Magnesium has another important function since in fact makes maintaining the correct combination of calcium concentration and alkalinity or carbonate hardness possible.



The explanation is as follows. Calcium forms with carbonates and bicarbonates an insoluble compound called calcium carbonate. Yes this is indeed an important building stone for corals and calcareous algae but then it should be formed by biological processes and be deposited at the right place. Therefore formation of calcium carbonate by chemical processes should be avoided.



Even without biological interference calcium carbonate would be formed and would deplete calcium and alkalinity or carbonate hardness without fulfilling any function. In fact it will scavenge many important trace elements as well lowering the trace element concentration.


Magnesium slows down this negative process. The lower the magnesium concentration the faster this negative process will take place and also at a much lower calcium and alkalinity/carbonate hardness value.



Maintaining a correct magnesium concentration is therefore very important and is indirectly responsible for fast coral and calcareous algae growth by virtue of making the maintenance of correct calcium and alkalinity figures possible.



Magnesium is depleted by algae and is also depleted by the use of excessive kalkwasser and by going far beyond natural calcium and alkalinity and pH values.



There are also certain brands of salt, which have or had a dramatically low magnesium content. Use of such a salt will result in permanent problems with calcium and carbonate hardness values. "
 
Randy,

Plants and animals don't necessarily have similar ionic ratios in their body fluids. For example, many sessile animals will have nearly seawater levels of Mg. Something like cuttlefish might have a Mg conc. reduced to just 15-20% of seawater conc. Mg is known to work as a sedative for certain invertebrates and it's hypothesized that they, since they are so active, do this as a means to sustain their activity. I known certain plankters actively pump sulfate and, if I recall correctly, Mg out of their cells (and preferentially replace them with lighter ions) as a means of buoyancy control.

Chris
 
I'll have to look. This is something I recall being mentioned briefly in an invert. bio class I took awhile ago. I'll see what I can dig up.
 
In this paper they chopped up and analyzed a marine algae (Enteromorpha spp.)


Chemical composition and microbiological assays of marine algae Enteromorpha spp. as a potential food source. Aguilera-Morales, M.; Casas-Valdez, M.; Carrillo-Dominguez, S.; Gonzalez-Acosta, B.; Perez-Gil, F. Centro Interdisciplinario de Ciencias Marinas, IPN, Laboratorio de Macroalgas, Becario COFAA y EDI Apdo. Postal 592, B.C.S., Mex. Journal of Food Composition and Analysis (2004), Volume Date 2005, 18(1), 79-88. Publisher: Elsevier Ltd.,

Abstract

Enteromorpha spp. is a marine seaweed present almost year round. It often causes unsightly appearance and foul odor from decompn. by micro-organisms. This generates expenses in cleaning beaches. This work dets. chem. and microbiol. compn., toxicol. evaluation of Enteromorpha spp., and recommends its use in human diets and promotion for com. exploitation, and provides a soln. to an ecol. problem. The seaweed was collected by hand on the beach during the winters of 1997 and 1998 along the Malecon (street and sidewalk adjacent to the beach) of La Paz, Baja California Sur, Mexico. Chem. anal. indicated that Enteromorpha spp. has 9-14% protein; 2-3.6% ether ext.; 32-36% ash, and n-3 and n-6 fatty acids 10.4 and 10.9 g/100 g of total fatty acid, resp. The protein of this seaweed has a high digestibility (98%). Salmonella was not found and mesophilicaerobic and fecal coliform did not exceed the norm. Alkaloids, cyanogenic glycosides, saponins, and tannic acid were scarce to null. Enteromorpha spp. is recommended for human consumption because it has several beneficial components, such as minerals, protein, essential amino acids, essential fatty acid, and fiber.


The results show far less magnesium relative to other ions in seawater as a percentage of seawater concentration.

Ion..........g/100 g dry weight
Sodium.........7.7
potassium.....1.1
calcium..........2.1
magnesium....0.43
phosphorus....2.7
Zinc................0.05 ppm
 
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