It is a hypothesis but with some evidence. There is the bacteria farming hypothesis: Bacteria are far superior to corals in acquiring phosphate. To fuel the bacterial growth and the enrichment of phosphate corals excrete much of the organic carbon and organic nitrogen produced by the zooxanthellae as slime and dissolved organic carbon. Bacteria at the slimy surface of corals and even in detached slime grow and accumulate phosphate. The corals feed on the slime and particles caught in the slime from their surface and also on detached slime that has caught nutritious particles in the environment.
Yuri I. Sorokin found out and published in his articles and in his book on "Coral Reef Ecology" (Springer) that corals don't show net phosphate uptake (or even net phosphate loss) below thresholds like 0.02 ppm phosphate which are typical for reef environments . Feeding on bacteria and other forms of particulate phosphate may be a way to overcome this problem.
Wouldn't a substantial population of fish poop not also solve coral uptake of particulate phosphate including feeding pellets which traditionally high in phosphates? Seems many reefers panic when poop falls on their beloved coral and perhaps grabbing the turkey baster not the prudent approach. Perhaps let it be
Which papers would be wrong if Sorokin is right?Assuming that assessment is true and other papers are wrong, that may be why folks find levels higher than 0.02 ppm phosphate desirable.
A holistic overview on mucus (carbon dosing) should also show it causes a net uptake and retention of P in sediments. Meaning less in the bulk water column.
The problem is not the absolute quantity of phosphate, the problem is the concentration. From water flowing over the reefs and an average of 2 m water column over the reefs there is no lack of phosphate. The problem is that the concentration is so low, the phosphate is so diluted, that it is difficult for corals to gain enough. It is not a high caloric cake but rather a very thin soup. The challenge is not to get it but to eat enough.
www.nature.com
I don't think that results must necessarily be wrong. Always there may be differences between species, origins, adaptations and kind of experiments.All of those that show corals taking up inorganic phosphate at levels below 0.02 ppm DIP, assuming that is what Sorokin claims won't take place.
This paper, for example, shows four different species take up DIP at concentrations less than 0.1 uM (less than 0.01 ppm).
Limited phosphorus availability is the Achilles heel of tropical reef corals in a warming ocean - Scientific Reports
During the 20th century, seawater temperatures have significantly increased, leading to profound alterations in biogeochemical cycles and ecosystem processes. Elevated temperatures have also caused massive bleaching (symbiont/pigment loss) of autotrophic symbioses, such as in...
"Concentrations remained below 0.5 μM for total DIN and below 0.1 μM for DIP."
Data in Figure 2C
"(a) Uptake rates of ammonium (μmol NH4 h−1 (mg prot)−1) (b) nitrate (μmol NO3 h−1 (mg prot)−1) and (c) phosphorus (μmol PO4 h−1 (mg prot)−1) for the different species at 25 °C (white color) and 30 °C (black color). Data are expressed by means ± standard deviations. Significant effects of the temperature factor were highlighted by an asterisk (*)."
https://www.nature.com/articles/srep31768/figures/2
I like your contributions, also if we do not always share the same opinion (but I think in general we do).
I like your contributions, also if we do not always share the same opinion (but I think in general we do).
The nubbins did grow prior to the experiments so they likely have taken up phosphate from the oligotrophic seawater. Nevertheless it is diffcult to find definite answers at these low concentrations. If I understood it right unfiltered natural seawater was used to keep the nubbins.
There have been questions about our products and I think it contributes to this thread to show up some of the difficulties and how I came to my conclusions, besides experiments and experience.
The article I have linked regarding the citation [63] might be a key article to understand the relative importance of phosphate, nitrate and ammonium for coral nutrition.
This is why I always mention that concentrations of 5 or 10 or more ppm nitrate have nothing to do with nutrients for corals. It must be a different effect, maybe of nitrate as an oxidant.
Anecdotal at best, but it's been a year of more zero than not.This is my old 75g. It's been broken down and all contents went into my 150g.
I was dosing nitrate but I stopped. That's was in April last year. Then started dosing ammonium chloride but was getting cyano mats. Stopped that too.
Nitrate in the 150 are trending down as things are growing. I will test later when I get home today. I feed my fish 4 times a day.
Are you carbon dosing at all?Anecdotal at best, but it's been a year of more zero than not.
I got some decent size colonies too.
The point I was trying to convey in earlier posts is, you can't target coral with any food that doesn't also target your filter (rock, sand, refug.....) And that filter is not a passive passenger, it can dominate water chemistry in both good and bad ways.
