What else can I do to get better color?

[MCsaxmaster]

How do sps corals maintain (keep or release) their population levels of zoox?

Good question. It is generally thought (and there's good supporting evidence to believe this) that zooxanthellae in hospite are nutrient (probably N) limited. Therefore, they have fairly static population sizes in the coral, although there is a daily turnover of zooxanthellae (some divide and some die). Corals can also release zoox. into the coelenteron and expel them, although for whatever reason most don't seem to be all that accomplished at this, hence "browning out" during N enrichment.

"practices for maintaining corals in aquaria: (1) remove DON and DOP because some of the compounds may be toxic to some organisms;"

Like I said, allelochemicals and probably some metabolic byproducts can be harmful. This is only a very small proportion of the total DOC/N/P in a tank though (or at least one would think).

They talk about inorganic nutrients being taken up by corals but dissolved organic nutrients being harmful. And on a side note they were able to see good coral growth in nutrient rich but low ph (high CO2) water which I found interesting.

DIN is readily taken up by corals (though it is usually <1/3 the total nitrogen budget and is about equivalent to losses in mucus for most corals). Orthophosphate is taken up, but not very effectively. DOP and particulate sources especially of P are much more accessible to corals.

DOC, DON and DOP are all taken up by every coral ever studied in this regard, although some do it more actively than others. Realize that these terms cover literally millions of substances and are really just an artifact of the way we sample (i.e. usually anything below 1 um is "dissolved"--that then gets denatured to inorganic C, N, and P and that is measured. The composition of the original substance is completely lost).

Yes, they saw good coral growth in elevated nutrients as compared to a reef, but this was still undetectable or just barely so on a hobbyist test kit. The nutrients were still pretty dilute. The pH was low, but the alkalinity was elevated. Other studies have demonstrated that most corals are not harmed by slightly elevated dissolved nutrients and calcification is enhanced under alkalinity enrichment.

Chris

 

[moumda]

IME, when I added a second skimmer and starting skimming wet I got better (deeper and more intense) coloration in my sps. Just a thought.

 

[kimoyo]

Chris,

Have you seen any models for nitrate assimilation in corals? I've seen models for ammonium assimlation (Miller & Yellowlees) but nothing to explain nitrate uptake which has been shown. With an increased ammonium level a study should good skeletogenesis regardless of elevated nitrate levels.

I recently saw a local reefers tank with 40ppm nitrates and excellent color and growth. He also has a huge fish load and good photoperiod. What's even more interesting is his frag tank which is tied into his system. Whereas his main tank has awesome growth and colors, the frag tank is mostly brown. The difference being he puts his old bulbs from the display over it.

It makes sense that with the large fish load ammonium is more available than most systems, but I would really like to tie in nitrates in my thoughts.

Thanks.

 

[MCsaxmaster]

Here are a few to get you started:

Might be hard to find, but very important if you can track it down. I might be able to find a scanned copy for you.

Bythell, JC 1988. A total nitrogen and carbon budget for the elkhorn coral Acropora palmata (Lamarck) Proc 6th Int Coral Reef Symp 2: 535-540.

Grover R., Maguer J.-F., ALLEMAND D., Ferrier-Pagès C. Nitrate uptake in the scleractinian coral Stylophora pistillata. Limnol. Oceanogr. 48 (6) : 2266-2274.

Szmant AM (2002) Nutrient enrichment on coral reefs: is it a major cause of coral reef. decline? Estuaries 25: 743-766.

There are many, many other papers on this general topic, but this will get you off to a good start.

And a website to check out:

http://www.bbsr.edu/lipschultz.htm

Corals actively take up nitrate and ammonium both (at least most do anyway...some contention about Madracis mirabilis recently). Most will take up ammonium preferentially, but there is usually more nitrate available than ammonium (though not much of either). This is rate limited (as recent studies suggest) only by the rate of diffusion through the boundary layer.

Chris

 

[kimoyo]

Thanks Chris,

Actually I found a bunch of articles on Prof. Szmant's course website. I just emailed her, hopefully she gets back to me. If you could find a scanned copy that would be awesome. Randy also found this article which I going to try to find.

<a href=showthread.php?s=&postid=6739459#post6739459 target=_blank>Originally posted</a> by Randy Holmes-Farley
This article may cover it (or not, I do not have it):

The symbiotic anthozoan: a physiological chimera between alga and animal. Furla, Paola; Allemand, Denis; Shick, J. Malcolm; Ferrier-Pages, Christine; Richier, Sophie; Plantivaux, Amandine; Merle, Pierre-Laurent; Tambutte, Sylvie. UMR 1112 INRA-UNSA, University of Nice-Sophia Antipolis, Nice, Fr. Integrative and Comparative Biology (2005), 45(4), 595-604. Publisher: Society for Integrative and Comparative Biology.
Abstract

A review. The symbiotic life style involves mutual ecol., physiol., structural, and mol. adaptations between the partners. In the symbiotic assocn. between anthozoans and photosynthetic dinoflagellates (Symbiodinium spp., also called zooxanthellae), the presence of the endosymbiont in the animal cells has constrained the host in several ways. It adopts behaviors that optimize photosynthesis of the zooxanthellae. The animal partner has had to evolve the ability to absorb and conc. dissolved inorg. carbon from seawater to supply the symbiont's photosynthesis. Exposing itself to sunlight to illuminate its symbionts sufficiently also subjects the host to damaging solar UV radiation. Protection against this is provided by biochem. sunscreens, including mycosporine-like amino acids, themselves produced by the symbiont and translocated to the host. Moreover, to protect itself against oxygen produced during algal photosynthesis, the cnidarian host has developed certain antioxidant defenses that are unique among animals. Finally, living in nutrient-poor waters, the animal partner has developed several mechanisms for nitrogen assimilation and conservation such as the ability to absorb inorg. nitrogen, highly unusual for a metazoan. These facts suggest a parallel evolution of symbiotic cnidarians and plants, in which the animal host has adopted characteristics usually assocd. with phototrophic organisms.

Thanks for your help.

 

[MCsaxmaster]

You should be able to get access to that article through Alina's site if you can't elsewhere. She may get back to you, but don't take it personally if she doesn't. She's quite busy. Actually, I've been talking with the folks in that lab since last semester. There's a good chance I'll be going there this fall.

Chris

 

[kimoyo]

Professor Szmant was pretty cool. She talked to me about a few things. She told me that there wasn't much done on it and that nitrate transporter system in corals is a good place for research for someone interested. Maybe thats something you could work on .

If your interested my local club is having a discussion about this here.

 

[MCsaxmaster]

Maybe thats something you could work on .

Ha, we'll see, we'll see. Something worth the effort, no doubt, but there are other things that are, to me, more pressing.

Chris

 

[Pygmey]

One more thing

One more thing

The quality of the skimmer means nothing if you are not feeding it the correct water. The skimmer should get as raw of water from your tank as possible. Also if there is not alot of flow or any dead spots in your tank they will become a nitrate factory. Go to All Things Salty forumn and read the sticky at the top of the page for skimmer production.

HTH

Eric