Nitrates in an SPS Tank

[Ebby]

At high light intensities and large zoox populations there's a point where the coral can't keep up with the demands of photosynthesis for CO2 (carbon source). What happens then? The zoox start drawing directly on the carbonate/bicarbonate entering the coral severely inhibiting calcification/skeletogenesis, almost halting growth and possibly leading to the death of the coral.

Dr. Szmant talked about this in her lectures and I know of several research papers that support this. Look up Marubini & Atkinson 1999, "Effects of lowered pH and elevated nitrate on coral calcification", they did a study showing exactly this.



Sounds like you understand this pretty well and probably better than me . So you know that "blasting" the corals can cause oxidative stress, which leads to super oxide radicals and peroxide, which cause zoox breakdown (loss). This is one of the forms of zoox loss I was referring to.

i know that increasing irradiance results in an increase in photosynthesis rates. now the high irradiance will create and even more hyperoxid condition that will lead to damage in both zoox and coral tissues, but it is known that corals are more sensitive to reactive oxygen species (ROS). so in this situation, imbalance between ROS production and antioxidant defense leads to cellular damage, and sadly the coral will suffer the most. so i don't think that the zoox loss will be benefical at all.

zoox transfer to their host 95% of their photosyntetic products thereby contributing to a variety of nutritional requirements, such as maintenance, synthesis of new cells, skeletal matrix, mucus, deposition of calcium carbonate and storage of energy-rich compounds for coral reproduction (yossi loya, 2001). thus, when coral a loses its zoox, it loses its main energy resource, putting at risk its essential functions.

and finally about this competition for C that you mention before, well at daytime the intake of carbonates\bicarbonates increases and the main reason is to support the photosynthesis happening in the zoox, so i don't really think that inhibition of calcification is happening under this conditions.

 

[ShaunW]

I'm not sure this is walking the line between life or death; its not about bleaching the coral. Using Dave's early analogy, we all need fat but too much isn't a good thing. All your doing is giving the coral a good amount (not an extreme amount) of good light, trying to create a very low nutrient system and dosing amino acids. Except for the dosing amino acids, most hobbyist try to do this anyway.

The reason that I say life or death is as Ebby has just pointed out. Inducing a increased oxidative stress response above what is normally experienced in corals (by zoox loss and increased light intensity above normal) will cause them to become "lighter" due to their defensive production of pigments, however the over production of reactive oxygen species is not a healthy state for any living organism.

 

[kimoyo]

and then zoox transfer to their host 95% of their photosyntetic products thereby contributing to a variety of nutritional requirements, such as maintenance, synthesis of new cells, skeletal matrix, mucus, deposition of calcium carbonate and storage of energy-rich compounds for coral reproduction (yossi loya, 2001). thus, when coral a loses its zoox, it loses its main energy resource, putting at risk its essential functions.

Ebby, I believe most of us understand the positive things zoox do for the coral and that is not in question. But they also do the negative things (from different perspectives) I've been talking about in this thread. The idea is not to eliminate the zoox but limit their population. Do you think having an elevated zoox population is good for the coral?

thus, when coral a loses its zoox, it loses its main energy resource, putting at risk its essential functions.

It has been shown that corals can absorb amino acids directly from the water.

and finally about this competition for C that you mention before, well at daytime the intake of carbonates\bicarbonates increases and the main reason is to support the photosyntesis happening in the zoox, so i don't really think that inhibition of calcification is happening under this conditions.

I was under the impression that zoox usually get their carbon source from CO2. Where are you getting that the zoox normally use carbonates/bicarbonates for photosynthesis? A model of this intake was shown earlier in this thread.

I thought the reason ph climbs when the lights are one is because of the draw on the CO2.

The theory that zoox compete with the coral for bicarbonates is not new nor my theory. I seen it explain in several respected papers, such as the one I referenced before, and the experiments done support it.

i know that increasing irradiance results in an increase of photosynthesis rates. now the high irradiance will create and even more hyperoxid condition that will lead to damage in both zoox and coral tissues, but it is known that corals are more sensitive to reactive oxygen species (ROS). so in this situation, imbalance between ROS production and antioxidant defense leads to cellular damage, and sadly the coral will suffer the most. so i don't think that the zoox loss will be benefical at all.

Yes there can be damage to coral tissue but we not trying to bleach the coral. If we're going to bleach the coral there's not point.

but it is known that corals are more sensitive to reactive oxygen species (ROS).

Is there a reference I can read for this?

 

[kimoyo]

Paul, it will be interesting to see if it works, . Personally, I'm more of a purist at heart, i.e. keeping the system simpler than more complex. For me, BB, with monthly 1/3 tank water changes and an efficient skimmer works well. Normal amounts of lighting and daily feeding of different foods. I gave up on adding supplements years ago, the cost/reward ratio was too high to justify.

BTW, how much light are you actually talking about anyway? 2 400watt MH over a 30 gallon tank? or something much less?

Doesn't Iwan use T5's (but I may be wrong)?

No not two 400W MH over a 30g. The t5's give uniform light over the entire tank which is different than MH's and important. So it would be a bulb over the length of the tank for every 2.5-2.75" of depth. So for my 120 (24" deep) I'm putting 8 t5 bulbs on it or 432 W of t5 light. Maybe I shouldn't have said "blasting" :lol2:.

 

[kimoyo]

The reason that I say life or death is as Ebby has just pointed out. Inducing a increased oxidative stress response above what is normally experienced in corals (by zoox loss and increased light intensity above normal) will cause them to become "lighter" due to their defensive production of pigments, however the over production of reactive oxygen species is not a healthy state for any living organism.

But I don't see why a reduction of zoox is bad; most of strive to not have brown corals. The intention is not to bleach the coral but pigment production is important to getting those colors.

I believe they (Iwan) are dosing something to aid this process.



Ebby or Solbby,

Can either of you explain why we see a lightening of zoox pigment when exposed to a good amount of light? Thanks.

 

[ShaunW]

No not two 400W MH over a 30g. The t5's give uniform light over the entire tank which is different than MH's and important. So it would be a bulb over the length of the tank for every 2.5-2.75" of depth. So for my 120 (24" deep) I'm putting 8 t5 bulbs on it or 432 W of t5 light. Maybe I shouldn't have said "blasting" :lol2:.

:scratchch

Your actually not using that much intense light as I thought. Do you think that this much light would limit zoox????

I have 3 250 watt MH and 440 watts of VHO over my 120 gallon!!!! :lol: Maybe I am the one that is limiting zoox production, :biglaugh: .

 

[kimoyo]

:scratchch

Your actually not using that much intense light as I thought. Do you think that this much light would limit zoox????

I have 3 250 watt MH and 440 watts of VHO over my 120 gallon!!!! :lol: Maybe I am the one that is limiting zoox production, :biglaugh: .

:lol2:, oh man lol. And you guys are getting after me for blasting my tank. But for real, low nutrients are also very important to this as you know. So combining the low nutrients with the good lighting should help to limit the zoox. I am curious what would happen to your tank if you starting adding supplements.

Whats your lighting schedule? Also, you do have a 20K bulb in the middle, if it was a 10K then you would be blasting that tank . The difference with t5 is you get the same par over the entire tank. Halides don't do that and I do think it makes a difference.

 

[ShaunW]

I am not sure what supplements would do to my system. But it is a risk that I am not yet willing to take since my colors and growth are exploding.

I have access to purified forms of amino acids. I could easily create a nutritional mix, but I still question whether the corals would get any due to bacteria getting it first. Remember the fastest growing organism is always going to utilize nutrients the most and fastest of all species present. Bacteria win in that regard. I also think that a genetic factor is important in that chosing corals that are genetically colorful.

My light schedule is:
8 hours VHOs
7 hours of a 20K center MH
5 hours of the left and right 10K MH.

 

[alrha]

:scratchch

Your actually not using that much intense light as I thought. Do you think that this much light would limit zoox????

I have 3 250 watt MH and 440 watts of VHO over my 120 gallon!!!! :lol: Maybe I am the one that is limiting zoox production, :biglaugh: .

:lol: and i have 3x400W MH and 2x140W VHO on my 187.
seems like we are already half way there on your theory Paul...

what about the duration of the light? wouldnt it make a difference if you had supper powerful lights over a short period vs less powerful lights over a longer perid?

 

[jhale]

my lights are similar to shauns, 3x250 10k's across the tank and 280 watts of actinic. I plan on adding some L3 reflectors in the future.
regarding dosing amino acids, I have been using seachems product, reef plus, off and on for the past year. It contains the following.



It's hard to say if the supplements have helped, I do not think they have hurt in any way. The color of my coral seems to be good and the growth is steady despite a battle with Po4, and now some No3 in the system.

 

[ShaunW]

Paul I suggest you read this paper!

http://www.journals.royalsoc.ac.uk/...fg/contributions/w/l/j/w/wljwlqwjnuqeyb4e.pdf


Regulation and control of intracellular algae (= zooxanthellae) in hard corals


R. J. Jones, D. Yellowlees

Abstract:


To examine algal (= zooxanthellae) regulation and control, and the factors determining algal densities in hard corals, the zooxanthellae mitotic index and release rates were regularly determined in branch tips from a colony of a staghorn coral, Acropora formosa, recovering from a coral 'bleaching' event (the stress-related dissociation of the coral?algal symbiosis). Mathematical models based upon density-dependent decreases in the algal division frequency and increases in algal release rates during the post-bleaching recovery period accurately predict the observed recovery period (ca. 20 weeks). The models suggest that (i) the colony recovered its algal population from the division of the remaining zooxanthellae, and (ii) the continual loss of zooxanthellae significantly slowed the recovery of the coral. Possible reasons for the 'paradoxical' loss of healthy zooxanthellae from the bleached coral are discussed in terms of endodermal processes occurring in the recovering coral and the redistribution of newly formed zooxanthellae to aposymbiotic host cells. At a steady-state algal density of 2.1 x 106 zooxanthellae cm-2 at the end of the recovery period, the zooxanthellae would have to form a double layer of cells in the coral tissues, consistent with microscopic observations. Neighbouring colonies of A. formosa with inherently higher algal densities possess proportionately smaller zooxanthellae. Results suggest that space availability and the size of the algal symbionts determines the algal densities in the coral colonies. The large increases in the algal densities reported in corals exposed to elevated nutrient concentrations (i.e between a two- and five-fold increase in the algal standing stock) are not consistent with this theory. We suggest that increases of this magnitude are a product of the experimental conditions: reasons for this statement are discussed. We propose that the stability of the coral?algal symbiosis under non-stress conditions, and the constancy of zooxanthellae densities in corals reported across growth form, depth and geographic range, are related to space availability limiting algal densities. However, at these densities, zooxanthellae have attributes consistent with nutrient limitation.

 

[ShaunW]

After your done with that one read this one, then we can get on the same wavelength, plus I have another 10 papers to follow as a further homework assignment, .

http://jeb.biologists.org/cgi/reprint/208/2/277

Symbiosis-induced adaptation to oxidative stress

Sophie Richier1, Paola Furla1, Amandine Plantivaux1, Pierre-Laurent Merle1 and Denis Allemand1,2,*

1 Universit? de Nice Sophia-Antipolis, BP 71, F-06108 Nice Cedex 02, France
2 Centre Scientifique de Monaco, Avenue Saint-Martin, MC-98000 Monaco, Principality of Monaco

* Author for correspondence (e-mail: [email protected])

Accepted 1 November 2004

Cnidarians in symbiosis with photosynthetic protists must withstand daily hyperoxic/anoxic transitions within their host cells. Comparative studies between symbiotic (Anemonia viridis) and non-symbiotic (Actinia schmidti) sea anemones show striking differences in their response to oxidative stress. First, the basal expression of SOD is very different. Symbiotic animal cells have a higher isoform diversity (number and classes) and a higher activity than the non-symbiotic cells. Second, the symbiotic animal cells of A. viridis also maintain unaltered basal values for cellular damage when exposed to experimental hyperoxia (100% O2) or to experimental thermal stress (elevated temperature +7?C above ambient). Under such conditions, A. schmidti modifies its SOD activity significantly. Electrophoretic patterns diversify, global activities diminish and cell damage biomarkers increase. These data suggest symbiotic cells adapt to stress while non-symbiotic cells remain acutely sensitive. In addition to being toxic, high O2 partial pressure (PO2) may also constitute a preconditioning step for symbiotic animal cells, leading to an adaptation to the hyperoxic condition and, thus, to oxidative stress. Furthermore, in aposymbiotic animal cells of A. viridis, repression of some animal SOD isoforms is observed. Meanwhile, in cultured symbionts, new activity bands are induced, suggesting that the host might protect its zooxanthellae in hospite. Similar results have been observed in other symbiotic organisms, such as the sea anemone Aiptasia pulchella and the scleractinian coral Stylophora pistillata. Molecular or physical interactions between the two symbiotic partners may explain such variations in SOD activity and might confer oxidative stress tolerance to the animal host.


Key words: cnidarians, zooxanthellae, symbiosis, oxidative stress, hyperoxia, thermal stress, SOD

 

[kimoyo]

:lol: and i have 3x400W MH and 2x140W VHO on my 187.
seems like we are already half way there on your theory Paul...

You guys are funny! But its not my theory, just trying to talk about what I think others are doing.

what about the duration of the light? wouldnt it make a difference if you had supper powerful lights over a short period vs less powerful lights over a longer perid?

Yep.

 

[kimoyo]

Paul I suggest you read this paper!

http://www.journals.royalsoc.ac.uk/media/e3d05pqywpdwycutmtfg/contributions/w/l/j/w/wljwlqwjnuqeyb4e.pdf


Regulation and control of intracellular algae (= zooxanthellae) in hard corals


R. J. Jones, D. Yellowlees

Thats looks like a very good paper! Can't do it today but tomorrow night I'll read thru it. Thanks.

 

[kimoyo]

Sean,

I saw your going away for vacation so I'm reading the articles tonight and will be around tomorrow to discuss if you want. If not, have a great vacation and I'll talk with you when you get back.

Paul

 

[ShaunW]

Thanks Paul! I actually have a stack of papers to read on the plane ride (8 hours) all about corals symbiosis, . So we can get back to the good stuff when I return (tomorrow I am going to be really busy at work preparing for my time off). Anyway post up you opinions about them as soon as you wish, so we can get the discussion rolling again, .

 

[jhale]

:bump:

any new ideas? My nitrates are back down and the coral looks the same.