Nitrate vs Phosphate uptake levels - species specific ratios

[MadTownMax]

After hearing Richard Harker's presentation at a SV-SEA club event (October), I decided to check out an article he was quoting that said that some macroalgaes have an uptake ratio of 200:1 Nitrogen:Phosphate

http://www.botany.hawaii.edu/Bot482/...Mar%20Biol.pdf


It was a real eye opener as to how these macroalgaes & marine plants function contrasted to how many people use them in their refugiums - each has their own specific ratio

With most reef tanks having very low nitrogen (like 1-2ppm) and even lower phosphate ( like 0.5ppm) it would seem that it would be in our favor to use species that have lower ratios, rather than the extremely high ones (200:1 is for one species of caulerpa, while 150:1 is the N:P ratio for another).

much thanks to Samala for giving a great presentation to the Delaware Reef Club last month and opening up my eyes to the wild world of Macro's

[Seahorsewisprer]

Is there one with a higher PO4 to NO3? That would be incredibly cool!

[Samala]

Havent found one yet Suzy.. Maybe.. I'll start taking macro and injecting fun phosphate uptake genes just for giggles. Instead, if you look at the article, there are several that have lower N:P ratios that are probably more appropriate to use. Not Caulerpa (since they're so high), but more like Gracilaria, Codium and Ulva.

>Sarah

[Seahorsewisprer]

Ok, I like a good research paper as much as the next girl, but........!!!

This one is cool! I really need to engage my brain! I did notice the graph with codium being a little better than the caulerpas, but that is my least growing green stuff.

I do have a piece of ulva, though. I'll watch it and see....It would be cool if it would take off, my tangs would be in Heaven!

[Samala]

Y'know another part of growing algae.. that the paper doesnt really address well, since it wasnt part of their plan of course, is competition for nutrients. They answered who needs what, not how they go about getting it.

I have a strong feeling that some macro are just more aggressive growers to begin with. Perhaps it has something to do with the capability of their nutrient transporters across the cell.. I'm not sure.

But.. have you heard of people saying their Caulerpa outran their seagrass, or other macros? I have! I think Caulerpas are just super aggressive growers, and they seem to be the first to snag the nutrients from the water column. So if you've got competing macro in a closed environment.. Ulva, Codium, Gracilaria, Caulerpa, its a toss to decide who'll win the war and gain the most weight in biomass. Even though the first three exist off a lot less nitrogen.. maybe thats an indication that they have had to evolve to live off of less nitrogen, becuase they are not well adapted to pulling lots of it out of the water column.. or.. better.. that they live in areas where nitrogen isnt in abundance. One of those explanations or others..

It would be more anecdoctal evidence from us.. but if you take the high N:P ratio players out of your existing tank.. do you find that the low N:P ratio macros grow faster? Precisely, exclude Caulerpa, do you still have good water quality, with fast growing edible macros for your herbivores?

>Sarah

[Plantbrain]

N:P ratios internally vs external levels are two very different things.

We know from FW and other plant studies, that rastios becuome an issue under limiting conditions, if you provide good conditions for growth, this will not occur.

If you limit the P and N a lot, you end up with Cyano often times.........
P can drive NO3 uptake, if the P is limited.

Plants/macros can concentrate certain nutrients vs their external environment.

Also, they may have luxury uptake, so the N:P dry weights have little meaning under those conditions.

Some diatoms can store enough polyphosphate to live for 100 generations. Macros are much less, but you stilol can see a huge storage ability.

Basically though, a ratio will not affect a plant/macro. It is the limitation that affects things.

I can have a PO4 of .2ppm, NO3 at 10ppm, or a .3ppm of PO4 and NO3 of 2ppm.

Plants will do fine in both cases if they are maintained at those levels.

It's generally easier for folsk to keep one higher and then monkey with the PO4, or have PO4 input from food etc mainly....

The two nutrients are dynamic.
the ratio itself have little meaning, NO3 and PO4 are very cheap to add to a tank, so it's not an issue of getting the most efficient use, it's more an issue of preventing a limitation. In the tank, we can enrichment the system easily, in natural systems, the ratio can infer/show a N or a P limitation.

Regards,
Tom Barr

[Seahorsewisprer]

Yes, but if we are using these organisms to remove PO4 from our reef tanks, it would be cool to get the most PO4 uptake from the smallest amount of space? I think it would be nice to find a substance that uptakes the same as my tank outtakes!

OK, that's worded weird, but if my enclosed system could just feed itself, that would be the ultimate in cool! If all I had to worry about was feeding my pet fish!

My caulerpas grow extremely fast compared to any of the other stuff, hands down. i have a C.pelata that I seem to need to prune daily! I don't want to remove them comepletely, but if I used less, do you think my reds would grow better?

[Samala]

They did touch a bit on luxury uptake vs. storage capacity for macros in that paper a bit - I thought it was very interesting:

"Under conditions of very low nitrogen and phosphorus availability, it is likely that tissue TN:TP ratios reflect the relative requirements of an alga for nitrogen and phosphorus. Conversely, when water column nitrogen and phosphorus are very high ... then tissue TN:TP ratios may reflect the storage capacity of one or both nutrients."

"High TN:TP ratios [internal] (>30:1 in tropical regions) have been considered to be an indication of phosphorus limitation, and luxury nitrogen storage in macroalgae, because maximum growth rates have been measured at TN:TP ratios of 10:1 to 20:1 ... Despite the high TN:TP ratios ... nitrogen storage seems to be limited in these species, as indicated by decreasing growth rates in unenriched seawater ..."

They go on to say that some of the species which maintained growth without outside N input did not have higher than average TN:TP ratios.

Also, I have induced sporulation in Caulerpas by NOT dosing nitrogen to test tanks. Their TN:TP ratios are very high, but they dont last long without outside N input. Perhaps this is because in the few days (which I had been calling kind of a buffer time) before sporulation they eat through their N stores. P limitation does not do this.

Anywho, I just thought that was very interesting. Everyone's tank seems to pull down its own living/breathing N:P consumption ratio. DRC members heard me say about 16:1 for my seagrass tank.. accumulation of those nutrients being consumed by macro, grass, a little LR and, basically, a non-anoxic DSB.

Tom.. its so great to see you around again. I always enjoy your postings.

Suzy - you just need to find an algae that keeps up with the tank right? Say your fish produce a ratio of 20:1 N:P.. then you gotta get some greenies that match that! Good luck! I think if you reduce the Caulerpas the reds might have more of a chance, yes. Dont take out too much at once of course.

>Sarah

[Seahorsewisprer]

Thanks! I'll see if I can't design a bit less with the caulerpas.

[Seahorsewisprer]

Thanks! I'll see if I can't design a bit less with the caulerpas.

[Plantbrain]

Originally posted by Seahorsewisprer
Yes, but if we are using these organisms to remove PO4 from our reef tanks, it would be cool to get the most PO4 uptake from the smallest amount of space? I think it would be nice to find a substance that uptakes the same as my tank outtakes!

OK, that's worded weird, but if my enclosed system could just feed itself, that would be the ultimate in cool! If all I had to worry about was feeding my pet fish!

My caulerpas grow extremely fast compared to any of the other stuff, hands down. i have a C.pelata that I seem to need to prune daily! I don't want to remove them comepletely, but if I used less, do you think my reds would grow better?

The issue is rate of removal, not so much space.
The biomass will change and occupy varying amounts of space through time.

If you stopped pruning the weed, the plant would crash.
You have balanced the biomass(through pruning, or export) to the rate of input (fish food etc).

Louse either one of those up, you will not be happy.
So if you stick with the pruning, you should do well.

I do not think about macro algae as filters or if they can help reduce my PO4 in my tank, I need to add PO4 to my tank, because it's a marine planted tank. I think in terms of horticulture.

I'd not compare our enclosed much higher nutrient, less stable systems to the reefs in the ocean. Nor the ratios found in natural systems, it's a good gauge, but that is all it is, a rough ratio of what is used.


Regards,
Tom Barr

[GABONE]

Has anyone used CaribSea's Phos Buster, and what results did they have?

[Biotoper]

Interesting article. Samala, your point on competition is key - from a competition-through-resource-limitation perspective, species vary at what concentration of X nutrient they show positive growth rate (referred to as R* in David Tilman's classic work on terrestrial plant competition). Thus, in theory, particularly in nutrient-limited systems, species will outcompete others by drawing down nutrients to levels below what others can survive at - so you would want to select species with low R*'s. In practice, those with lowest R*'s are generally the slowest growing, so, especially in a constantly pruned system, the faster, higher R* species will better compete for light, respond to harvesting better, and you're left with a tank full of Caulerpa!

It is nice how the paper addressed how most plants are surviving by increasing sedimendation and producing higher nutrient substrate solution. This is pretty obvious when you think of how lagoons serve as nutrient sinks for nutrient-poor reefs through sedimentation. This is counter to how most reefers try to reduce sedimentation in their fuge by increasing flow - in such cases plant growth might be much better if they allowed increased sedimentation.

Now, as Tom pointed out, for those of you that are going full-out planted tank and dosing, then most of this is all moot.

Ryan

[Plantbrain]

Ff you address the rate of removal/uptake, then you have a good idea how to apply that to a reef system.

In order to do that, you need to work with the plants without the other factors.

So planted tanks can help both the understanding to the plants themsleves and the use for reef aquarist.


Regards,
Tom Barr

[morphriz]

Originally posted by Samala
But.. have you heard of people saying their Caulerpa outran their seagrass, or other macros? I have! I think Caulerpas are just super aggressive growers, and they seem to be the first to snag the nutrients from the water column.

How do the seagrass fare in highnutrient substrates compared to macros? Wins out completely, no? I'm not familiar with how macros deal with such a senario.

[Samala]

Holy resurrected thread! In test tanks where the substrate is loaded with detritus, mud, fertilizer tabs, etc, and the water column is not dosed except for CO2 I can get Halodule wrightii to outcompete Caulerpa prolifera. I'm not sure that will extend to all plants and in all scenarios, but it held true for that particular tank.

In my display where both Halodule and prolifera inhabit a medium-rich bed (I think I just made up a new term.. I mean a bed with a little mud, not too much detritus and just a few fert tabs but mostly plain aragonite) and with water column dosing C. prolifera grows faster than Halodule, but the shoal grass holds its own. So, they both invade each other's space in this situation.

If I didnt prune and clip the garden I'm not sure who would dominate the tank. My bets are on the Caulerpa.

>Sarah

[morphriz]

I dont think you just invented a new term. You invented a hobby, grass- and macro-racing. I think it will be hard to attract the crowds though

For the macros, my interpretation of the article and this thread is that macros can simply be selected for a given senario. Subject to availability of course. Once I have a good idea on how much N and P is added to my tank I can choose a macro with a similiar, slightly lower in N, ratio to get a efficient export.

But how should I set up a tank to put the grass and the macros on as equal terms as possible? Add grass from the start and then add macros to suit the resulting nutrient situation?

When it comes to N uptake, are there any differences in NO3 to internally available N for plants and macros. I'm thinking about the fact that plants need to convert NO3 back to NH4 to be able to utilize it. If there is, the plants might be helped along by "nano" dosing NH4NO3 as part of NO3 dosing.

Man, marine planteds are more fun

[Samala]

Grass and macro' racing.. Slightly better than snail racing I suppose.

Honestly, I just give all the plants all the nutrients they want and never let the major ones bottom out (N P and hopefully I'm doinga good job with C). I worry about who's outcompeting whom by manually removing the trouble makers.

For instance, I harvest probably a quart bag of Caulerpa prolifera once per week to keep it in check. I have entertained the idea of ripping it out entirely but it does such a good job of indicating when N is low in the water by patchily dying back one or two small leaves. I also harvest about fifty plants of Halodule to keep it from totally choking itself and also from invading the LR areas, the Caulerpa, the Halymenia and other spots, such as the newer spaces upfront for Halophila seagrass.

Dynamic tank means you have to be a little more interactive with controlling how things will grow. I'd say marine planteds are a little more hands-on than most of us are used too.

Anywho, whatever you do, do NOT dose NH4NO3. I encourage experimentation but this is one chemical you do not want to mess with. The NH4 pretty consistently triggers massive microalga blooms (usually cyano in my tanks) before it will be consumed by the plants. I like to call it 'algae candy'.

>Sarah

[morphriz]

Originally posted by Samala

Anywho, whatever you do, do NOT dose NH4NO3. I encourage experimentation but this is one chemical you do not want to mess with. The NH4 pretty consistently triggers massive microalga blooms (usually cyano in my tanks) before it will be consumed by the plants. I like to call it 'algae candy'.

I forgot consider ammounium instability, like messing with the substrate in a FW withoud doing a WC, which always triggers algae.

Man, my fingers are itching here! And thoose french havent started harvesting macros for sale yet. I think I'll use altavista babelfish and go nag them some in french

[wong BANTEN]

[Samala]

Ok, now details on that graph pretty please. Conditions (light, water flow, number of mangroves, age of mangroves, how NO3 was quantified and delivered to the test tank, etc.) Without knowing all the information and design and the intention of the experiment that goes along with these results they dont mean anything.

>Sarah

[wong BANTEN]

You can cacth that link for detail.
the design is very simple,and No spesific flow, and Number of mangroves. Because there will lot of RULE thats make that data seems UNCORRECT. FYI, I did that methode for Two Years.
I have an article that compares the Mangroove relation with Different Wheater,MUD,and Element versus N and P absorbtion,...also the speed of grows.

[charlesr1958]

Originally posted by Samala
maybe thats an indication that they have had to evolve to live off of less nitrogen, becuase they are not well adapted to pulling lots of it out of the water column.. or.. better.. that they live in areas where nitrogen isnt in abundance. One of those explanations or others..


>Sarah

Actualy that makes a lot of sense to me. On the reef flats prior to the coral reef, it is nothing but macro algae with a band of sargassum kelp as well. Pick just about any species of macro algae and it can be found there....with one exception, no calurpa species at all. With nitrate and phosphate levels reading "zero" on my test kits, your above statement made me go...hmmmmm. I do see calurpa once in a great while, but it will only be a little sprig and looking like it is having a hard time, hardly worth the time it would take me to collect it. Although I have, and once placed into my aquarium system with its higher nitrate and phosphate levels, it took off like the weed it is know for being. While the other macro algae species just sat there with little growth. Once my nutrient levels approached the same level as the reef, the calurpa died while the other algae is still plugging away, but still at its slow growth rate. (compared to calurpa).

Chuck ( In the Philippines)

[morphriz]

Holy resurrected thread again..

[Plantbrain]

OKAY,
Now there was an original question posed and an example here, using a study to imply that we can get more PO4 uptake out our weeds to help a reef tank.

We want to use macros to remove PO4........
There are two main issues here:

1. The loading rate from the Reef tank
2. The lowest level you want of PO4.

Now if rate is the key,, the ratios really do not mean much for us.............
If you want the lowest PO4, then the rate might be your biggest issue, you want a mixture of macros, some that are really good at rate response changes of PO4, and then another species that can eaqt up the rest of very low levels of PO4.

Ideally, we'd want the fast higher rate response macro to just slow/stop growing vs melt, so Chaeto makes this a decent weed.

Then you need a weed that is about to grow well under lean levels of PO4.

We have issues measuring anything well at 10ppb.
Macros start to get weird down around that level.

So that's okay, the smaller noxious species can grow fine under 10ppb, so even testing with the best of the hobby(and even some Lab research methods) will not tell you if you limit PO4 for the microphytes.

But back to the issue at hand............
Rate..........if I have a weed that has a massive growth rate, thus PO4 uptake rate, even if the PO4 ratio is 2x less, but the growth rate is 4X more, I'll export more PO4 with the lower ratio weed.

You also need to take into account N efficiency as you depress the PO4, and also light intensity/use efficacy.

It's not this simple two box model here when dealing with growth rates and PO4/NO3 uptake.

Ease of care for the weed is another huge giant issue.........

I think folks obsess too much over nutrients and not enough with basic aquarium keeping skills(water changes, cleaning, pruning, scrubbing etc).

You cannot see the forest through the kelp..............

There is a strong temptation to use studies to support things you want to believe(ask Freud)..........and perhaps there is correlation..........
But do not believe everything you think.

Question everything.
Especially the really basic stuff.
Then design a test to see.
Hopefully it can answer your question with supportive results.
Then you have a much better understanding and one specific for your system of choice(aquariums).


Regards,
Tom Barr