The Redfield Ratio

[timvdb]

This is from a website referred to earlier in the forum. Ay thoughts?



"He read something about the so called Redfield ratio. That is the ratio between the quantity of nitrogen and phosphorus in the water. Several researchers have used the Redfield ratio to see what the influence is of different values on the occurrence of various types of algae. An article of Bulgakov et al. has been translated by Agnes Zaalinto Dutch; my thanks to her.



It seems that the change of getting green algae is big, if comparatively much nitrogen and little phosphorus is in the water. In reverse, little nitrogen c.q. a lot of phosphorus leads to a big change that you will start growing blue-green algae. The optimum seems to be at the proportion nitrogenhosphorus = 16:1. Which means a Redfield ratio of 16."




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[HighlandReefer]

Hobbyists measure nitrate and phosphate only normally. Cyano are a different breed than algae. They can fix nitrogen from the atmosphere, so how do you control this form of N (Nitrogen) for Cyano. They also can use organic phosphorous in addition to inorganic phosphate, so measuring phosphate only does not give you the complete picture for P sources in your tank for cyanobacteria.

From Wiki:

"Nitrogen fixation

Cyanobacteria cultured in specific media. Cyanobacteria can be helpful in agriculture as they have the capability to fix atmospheric nitrogen to soil.
Cyanobacteria include unicellular and colonial species. Colonies may form filaments, sheets or even hollow balls. Some filamentous colonies show the ability to differentiate into several different cell types: vegetative cells, the normal, photosynthetic cells that are formed under favorable growing conditions; akinetes, the climate-resistant spores that may form when environmental conditions become harsh; and thick-walled heterocysts, which contain the enzyme nitrogenase, vital for nitrogen fixation. Heterocysts may also form under the appropriate environmental conditions (anoxic) when fixed nitrogen is scarce. Heterocyst-forming species are specialized for nitrogen fixation and are able to fix nitrogen gas into ammonia (NH3), nitrites (NO− 2) or nitrates (NO− 3) which can be absorbed by plants and converted to protein and nucleic acids (atmospheric nitrogen is not bioavailable to plants).

Rice plantations utilize healthy populations of nitrogen-fixing cyanobacteria (Anabaena, as symbiotes of the aquatic fern Azolla) for use as rice paddy fertilizer.[4]


Cyanobacteria are arguably the most successful group of microorganisms on earth. They are the most genetically diverse; they occupy a broad range of habitats across all latitudes, widespread in freshwater, marine and terrestrial ecosystems, and they are found in the most extreme niches such as hot springs, salt works, and hypersaline bays. Photoautotrophic, oxygen-producing cyanobacteria created the conditions in the planet's early atmosphere that directed the evolution of aerobic metabolism and eukarotic photosynthesis. Cyanobacteria fulfill vital ecological functions in the world's oceans, being important contributors to global carbon and nitrogen budgets."

– Stewart and Falconer[5]

 

[HighlandReefer]

To say the least, cyanobacteria are a tough hombre to defeat and control in some cases when they become pests.


More from Wiki:

"Ecology

Many cyanobacteria also form motile filaments, called hormogonia, that travel away from the main biomass to bud and form new colonies elsewhere. The cells in a hormogonium are often thinner than in the vegetative state, and the cells on either end of the motile chain may be tapered. In order to break away from the parent colony, a hormogonium often must tear apart a weaker cell in a filament, called a necridium.

Each individual cell of a cyanobacterium typically has a thick, gelatinous cell wall. They lack flagella, but hormogonia and some species may move about by gliding along surfaces. Many of the multi-cellular filamentous forms of Oscillatoria are capable of a waving motion; the filament oscillates back and forth. In water columns some cyanobacteria float by forming gas vesicles, like in archaea. These vesicles are not organelles as such. They are not bounded by lipid membranes but by a protein sheath.

Some of these organisms contribute significantly to global ecology and the oxygen cycle. The tiny marine cyanobacterium Prochlorococcus was discovered in 1986 and accounts for more than half of the photosynthesis of the open ocean.[6] Many cyanobacteria even display the circadian rhythms that were once thought to exist only in eukaryotic cells (see bacterial circadian rhythms)."


"Many cyanobacteria are able to reduce nitrogen and carbon dioxide under aerobic conditions, a fact that may be responsible for their evolutionary and ecological success. The water-oxidizing photosynthesis is accomplished by coupling the activity of photosystem (PS) II and I (Z-scheme). In anaerobic conditions, they are also able to use only PS I — cyclic photophosphorylation — with electron donors other than water (hydrogen sulfide, thiosulphate, or even molecular hydrogen[8]) just like purple photosynthetic bacteria. Furthermore, they share an archaeal property, the ability to reduce elemental sulfur by anaerobic respiration in the dark. Their photosynthetic electron transport shares the same compartment as the components of respiratory electron transport. Their plasma membrane contains only components of the respiratory chain, while the thylakoid "

 

[disc1]

This is from a website referred to earlier in the forum. Ay thoughts?



"He read something about the so called Redfield ratio. That is the ratio between the quantity of nitrogen and phosphorus in the water. Several researchers have used the Redfield ratio to see what the influence is of different values on the occurrence of various types of algae. An article of Bulgakov et al. has been translated by Agnes Zaalinto Dutch; my thanks to her.



It seems that the change of getting green algae is big, if comparatively much nitrogen and little phosphorus is in the water. In reverse, little nitrogen c.q. a lot of phosphorus leads to a big change that you will start growing blue-green algae. The optimum seems to be at the proportion nitrogenhosphorus = 16:1. Which means a Redfield ratio of 16."




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Like most of these articles, the author doesn't understand what the Redfield Ratio means. It's not the amount in the water. It's the ratio of amounts found in plankton. Some algae can become nitrate or phosphate limited in some situations, but that isn't predicted by the RR. And cyano, as HighlandReefer pointed out, certainly isn't one of them.

The only apllication for the Redfield Ratio that applies to aquarium keeping that I can see would be if you were feeding the tank phyto and wanted to calculate the ratio of nutrients you were adding to the tank. Even then, since macro-algae and other organisms use those nutrients at ratios different from plankton you will not be able to use that to predict anything about what that will do to the levels in the tank.

 

[disc1]

Moreover, the Redfield Ratio speaks of total elemental C, N, and P, not just nitrate and phosphate. It also includes all the other organic forms that you can't test for.

 

[Ron Reefman]

David, do you ever get the feeling they can't hear you? :headwallblue:

 

[tmz]

I agree with the posts by Randy, David and Cliff .
For one more try:
the Redfield ratio is a measure of carbon, nitrogen and phosphaorus in marine organisms;not the water.It is a collective, en masse, measure. It is 116C(carbon) :16N (nitrogen) ;1P. WE don't measure the C since the equipment to do it is cost prohibitive .

Different organisms have varying needs for CNP to some degree.

N is also removed from the tank by conversion to N2 gas via anaerobic bacterial activity . This export reduction causes a greater proportion of N reduction than consumption by the organisms in the tank
Cyano can make it's own organic C and N from athmospheric CO2 and Nitrogen gas; it can be limitied by limiting inorganic phospahate( PO4 species). Green macroalgaes are limited at PO4 levels below .03.

 

[Yuri Barros]

Thanks for the posts..........very informative............

Now I understand RR..........

It was a bit confused to me...............but now I understand it much better..............

 

[Habib]

I had a discussion with Charles Buddendorf back in 2003/2004. He is the guy from the article/website some of you linked to or quoted from.

Unfortunately for many here, the discussion was in Dutch:

http://zeewaterforum.info/forums/archive/index.php/t-3440.html?