We really should be thinking more critically about nutrient number chasing...

galleon

New member
This is an awesome article from two folks exceptionally qualified to talk about the subject. Chris is a PhD candidate in marine biology who works on how and why coral reefs grow and do what they do. Rich curates the largest living reef aquarium on Earth, and has a beautiful home reef with stupid high phosphate levels. PLEASE don't close or ban me for posting the link. The article is really well written and there is a LOT to be gleaned from the "take a step back" approach that looks at the bigger picture.

http://www.reefsmagazine.com/forum/...g-ix-test-kits-chasing-numbers-phosphate.html
 
That is fascinating, thanks.

Interesting to see that some difficult SPS corals actually grow better under high phosphate conditions.

I have also, btw, had people claim to me they've eliminated various pest algaes via iron limitation and NOT phosphate limitation, as several examples in the article state. I wonder if more people in the future will try such strategies.
 
interesting.

the article starts by saying we limit po4, cause of the marketing hype ... not to lower algae or increase calcification.

then it shows examples of natural reefs, like hawaii, turning into swamps when po4 increased. algae taking over. some cases of this were documented.

Then they find an exception to this, where Iron is limiting and corals were not killed and overtaken by algae, but they grew more brittle due to higher po4 ...

so start of Iron removers ? what was the point ? it was shown through the article that high p04 is not desirable ... unless u can limit life [captivity test of growth of corals but no algae present] and other elements [Iron]

so Iron removers are going to come out now ? take over po4 removers ?

back in the days, there was a huge hole in the town, across the town from the hospital.
PPl fell in the hole often, broke their legs, and sometimes get injured more on their way to the hospital which was far away.
the city gets together to solve this, they fill the hole up, and dig another hole closer to the hospital ...

why not get rid of the problem instead ? rather than try to find a way to live with it, making peace with algae growth or limiting other elements of life ?

time spent removing dead corals that were taken over by algae, or the money spent on GFO, is no where close to the money it takes to replace corals ... or the labour of removing algae manually. after all, these are living animals, we want to give them the best conditions, rather than worst conditions right on the edge of them loosing life.

what would happen to authors reef after a rather large water change to replenish lost elements ? zoox and algae growing more ... zoox would make the corals brown, and algae would lover O2 which in turn might cause a disaster.... like what we are doing to natural reefs ...

too much contradictions IMHO.
 
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It's not really contradictory. It's explaining the science more concretely than the casual reefer will often think about.

PO4 limitation is a rule of thumb but is not necessarily bad for corals in and of itself. And, in fact, the article demonstrates that sometimes higher PO4 is actually beneficial to coral. Including sps.

It is not an editorial piece decrying the practice of PO4 limitation or arguing that it is nonsense with no scientific basis.
 
interesting.

the article starts by saying we limit po4, cause of the marketing hype ... not to lower algae or increase calcification.

"People have been shooting for 0.05 ppm or less as a level to keep their tank phosphate concentration, and this number is often cited as the concentration on natural coral reefs. Interestingly, the reality is that the PO43- * of natural seawater varies significantly on coral reefs in different locations. "

So given that the reality of natural variability and actual reef concentrations what else would you call such number chasing besides viral hearsay?

then it shows examples of natural reefs, like hawaii, turning into swamps when po4 increased. algae taking over. some cases of this were documented.

They discuss one case of phosphate enrichment. Another of iron enrichment.

Then they find an exception to this, where Iron is limiting and corals were not killed and overtaken by algae, but they grew more brittle due to higher po4 ...

The Line Islands are an HNLC region of the ocean. They do not grow more or less brittle. The skeletal bulk and micro density data were initially reported by Koop et al. as a result of ENCORE, on the Great Barrier Reef, a completely different environment. Confusing the two regions is an incorrect interpretation.

Additionally, the subjective interpretation of "brittleness" requires context. You are making a VAST subjective assumption about the implications of changing skeletal densities, whereas an objective interpretation is that the animal reproduced faster, making the colony larger in less time, under nutrient-enriched conditions.
 
From : Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach
Jeremy G. Dunna, b, c, 1, Paul W. Sammarcoa, c,

http://www.sciencedirect.com/science/article/pii/S0022098111004588



"Phosphate has been referred to as a “crystal poison” to the calcifying environment and the causative factor of coral density loss under nutrient enrichment (Kinsey and Davies, 1979, Risk and Sammarco, 1991 and Simkiss, 1964). Our results support recent studies that have demonstrated an increase in porosity and a decrease in density under phosphate-enriched conditions (Koop et al., 2001). This condition may cause the coral to be vulnerable to breakage or more susceptible to natural wave action and colonization by internal bioeroders, further decreasing its skeletal integrity (Risk et al., 1995 and Sammarco and Risk, 1990). A rapid “lean” linear growth and a trend towards the production of numerous branches would allow for increased surface area for photosynthesis and feeding. Although this trend would appear to be advantageous, as mentioned above, less heavily calcified corals may become brittle and more prone to breakage, and thus represent an unhealthy state."


we can get larger in less time taking steroids. but we dont. point is to be healthy and thriving, ... and get big/grow, not just getting big with nothing inside.
 
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...less heavily calcified corals may become brittle and more prone to breakage, and thus represent an unhealthy state

Skeletal density reduction may be due to phosphate binding at the calcifying surface and the creation of a porous and structurally weaker calcium carbonate/calcium phosphate skeleton

Reading the article, you should note that 1) There was no control using extremely low phosphate concentrations, such as those the authors themselves cite as "natural". 2) The first two treatments were approximately 10 and 20 times higher than the cited "typical" 0.01 mg/L value, and both had indistinguishable skeletal densities from one another. 3) Only the highest value, 50 TIMES the cited natural average, had any (and barely, even using their ANOVA) significant change in skeletal density during growth. Not to mention their method for determining relative density changes is highly questionable given use of wet weight and their lack of inclusion of ramet surface area, instead using length of the fragment. The most robust result of that study is that corals grew faster. The portions of this article based on the calculations and interpretations of density should have been rejected.
 
:)

ok so the article I posted, is questionable when it comes to corals at high po4 being less healthy.

but the part that showed corals grow more with higher po4 is not questionable ? and it became a trusted source all of a sudden ?

hmm. cant pick and choose :)
 
:)

ok so the article I posted, is questionable when it comes to corals at high po4 being less healthy.

but the part that showed corals grow more with higher po4 is not questionable ? and it became a trusted source all of a sudden ?

No. Try again. I actually read the article, and, it gets better: I would be a potential peer reviewer for this article. I'm telling you, as a coral scientist, which parts I find to be and not to be scientifically robust. That's the thing, you do get to pick and choose when you have the applicable training and are capable of making the distinction between what is and is not an interpretation of data that holds up to scrutiny. It's one of the perks of being a scientist. That's how the peer review system works. Data are data. How you cast those data into an interpretation is either robust, or it is not.
 
when what you pick and choose differs from observations, is when we loose faith in the 'scientists'
as thales would say "how do you know that" and you can not reply with "trust me, Im a scientist"

I did and do enjoy the discussion though, thanks

that whole article is flawed IMHO as well. problem is algae was eliminated from the test, in nature, algae would take over [high fertilizer] and kill the coral from lack of O2 ... or if Iron was limited, then the result would not be the same. I just used it, since parts of it conclusion was used in the article you posted to support the authors argument, and parts that disagreed were ignored.
 
when what you pick and choose differs from observations, is when we loose faith in the 'scientists'
as thales would say "how do you know that" and you can not reply with "trust me, Im a scientist"

Why put the word scientists in apostrophes? Who is we?

Who is picking and choosing anything regarding observations? Data are data, they are immutable. I said that in my last post. As Neil deGrasse Tyson said, “The good thing about science is that it's true whether or not you believe in it.”

Data ARE however subject to interpretation. Even statistical treatment to determine the extent of significance is an interpretation. And interpretations are exactly that: interpretations.

Scientists are professionally trained in their field to figure out which of those interpretations are good, and which ones are bad. Scientific Laypeople are not.
 
when what you pick and choose differs from observations, is when we loose faith in the 'scientists'.

Unfortunately, that's not correct. What happens is that the lay public incorrectly interpret that when there's disagreement among scientists at the edges of understanding, then all of science must therefore be equally subjective.

It's quite true that you can get many reputable scientists to disagree with each other about whether physical reality is composed of almost infinitesimally small energy vibrations on the scale of the planck length (sometimes called "string theory"), but no one will ever successfully build a perpetual motion machine, ever.

There are a ton of observations out there that are factually correct, yet the conclusions drawn from those factually correct observations may, or may not, be correct. Generally speaking, it requires years of observations and reams of scientific papers to gain an objectively true understanding of really complex systems (especially biological systems).
 
so as just a hobbyist when it comes to reefing. I can ask "how do you know that", Rich has thought me that. :)

have you ran an experiment that corals in high po4 grow better and are NOT brittle ?

pleas share the correct result and Data with us.

you should not expect me to believe everything you say, just cause you are a scientist. just like you should not believe everything I would say about electricity :) I could be wrong.
 
Okay, I removed a bunch of posts bickering about a misspelling. Please take such comments offline.

I hope to be able to read the article soon now. :)
 
old news....i had nice sps' tanks with .5 ppm P"0"4 more than 10 years ago!!!!
 
Galleon, thank you for posting this article! Locally what I am happy see occasionally posted when newbies ask question about "ideal" water conditions beside being given "numbers" there are also admonishments not to chase numbers. As Sprung said a long time ago in his monthly column there is much we can only determine "Qualitatively not quantitatively". Regarding ULNS aquaria Charles Delbeek said in Coral Nov/Dec 2010 pg 127 "Our crystal-clear aquaria do not come close to the nutrient loads that swirl around natural reefs. And so when we create low-nutrient water conditions, we still have to deal with the rest of a much more complex puzzle." I do not see the artice linked in the first post as advocating high phosphates but pointing out that phosphates are just part of the equation. It is not enough to just know that phosphates are usually low in wild reef systems but we need to know exactly why and what that means in our captive systems. We also need to know why phosphates are linked to algae problems in some situations but not in others. I personally am very interested as I see systems that are struggling because the aquarist is blindly chasing a zero tolerance towards ammonium, nitrates and phosphates when these nutrients are critical for corals(1)(2)(3). Beside the role corals along with their symbionts take in arguably being the central part of the filtration in our systems what also does not seem to be recognized by very many of the experienced aquarists and self appointed "Gurus" is just like people corals can not only be anorexic, starved with little brown coloration from Symbodinium spp. dinoflagellates, but also obese, or have too many symbionts.(4)

(An item that I did not see mentioned in this article is phosphates are a limiting nutrient for hermetic corals uptake of nitrates(2) which raises the question of nitrate issues being caused by not enough phosphates.)

For the record I do not advocate high phosphate levels and I do not want the following observations/post to be misconstrued as such! The following tank has been maintained for over 6 years with tap water. Initial phosphate test with Merk/Tunze High Phosphate was less than .25 ppm PO43 (no discernable color change, lowest color reference was .25). Within the last month the phosphates in the tap water tested as .14 ppm PO43 (Elos Professional). No GFO has been used in this system since the original acrylic tank was replaced with a glass tank in March of 2011. Water changes are every 10 to 21 days, mostly 10 - 11 days and on average a cup of Xenia is removed each month. In May 2011 the phosphates tested as 3.0 ppm PO43 (Merk/Tunze high phosphate) (Yes, that's 3.0 not .3). Two months ago the phosphates tested ~1.0 ppm PO43 (API, off the scale with Elos Professional), nitrates were undetectable with API. Two items of note, when I started maintaining this system 6 years ago there was both a serious Aiptasia and Valonia algae problem which have significantly abated with minimal intervention on my part. Herbavores are Cherub and Coral Beauty Angels, A yellow and two regal Tangs and a handful of hermits. Clearly SPS, or at least Green Slimmer, Bink Birdsnest and Montipora digitatus can be maintained with high phosphates without algae problems. AND! More importantly, reef aquaria can have processes that reduce the phosphates without external intervention.

http://www.youtube.com/watch?v=9Eckf4Jne40 May '11 PO43 ~3.0 ppm
http://www.youtube.com/watch?v=-eCQSVdqBQA Sept. '13 PO43 ~1.00 ppm

And considering calcium carbonate will dissolve in reef aquaria with the help of biological processes I am dubious of the claim it is being absorbed by the rock. This photo is of part of the Birdsnest colony from the above sysem that was killed when the colony was pruned. It shows the surface detail from part of the skeleton that was freshly dead (right side) and was not exposed to saltwater and part that that died from lack of light and was in the tank exposed for less than 8 or 9 months(left side). (Pruning was required because the colony had reaching the surface and would have started tabling killing off everything beneath it):



(1) http://www.ingentaconnect.com/content/umrsmas/bullmar/1979/00000029/00000004/art00011
(2) http://jeb.biologists.org/content/214/16/2749.full
(3) http://wap.aslo.org/lo/toc/vol_48/issue_6/2266.pdf
(4) http://www.sciencedaily.com/releases/2012/10/121014162914.htm
 
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