Application of argonomy to the growth of Macro algae

[Plantbrain]

For the sake of background and horticultural understanding and concepts this link and thread might be considered for a sticky.


http://www.netdor.com/ernestm/AGRON2.HTM

I will detail out some concepts here that are discussed based on this template. I feel this is a good background article for the basics in understanding the growth.

Many worry about the nutrients in terms of preventing some dreaded, feared algae, well macros are algae as well and they have a niche, just like corals and other critters and weeds.

I generally focus on the species of interest, what conditions provide the optimal growth? I focus solely on the plant in question, not worrying about other constraints, that comes later in the next step=>
What trade offs are associated in a community to achieve this optimal level for both the species and the community?

Is there a middle ground?

Generally yes.

So with these in mind:

Liebscher's Law of the Optimum

If your goals is the reduce PO4, then adding NO3 will increase the efficacy of the removal of PO4, the plant has non limiting conditions for NO3.

If you say try to limit both PO4 and NO3 at or near zero, you can alternate between NO3 and PO4 limitation. This can serious cause many issues for plants, especially larger plant systems(seagrasses, larger complex macro algae). The NO3 limitation stunts growth, this in turn causes little PO4 to be removed and you measure an increase in PO4 but low NO3.

After awhile, you'll measure NO3, and PO4, the plants are no longer using either due to stunting.

If you are patient and allow the PO4/NO3 to persist, after a few weeks, the plants will bounce back and yuou can repeat the cycle.

By dosing NO3 or PO4 or both, we may control this and provide stable uptake from the reef/main tank/planted macro algae tank etc.

The "magic prize" most aquarists seek is stability, not feast or famine.

Bobbing between a limiting and non limit situation is not desirable for most aquarist.

Yet much of the advice centers specifically on trying to achieve situations where precisely that occurs.

Some succeed, many do not.
those that do succeed generally have not tested well at the such low levels and may have other sources of PO4/NO3 coming/out that are stable, but beyond the test kit's ability.

You can dose very low amounts daily etc if you want to maintain and very low range, however, the question is, do we need such micro management?

Are the folks who think that absent nutrients are really the key, actually testing their systems with good methods and calibrated test kits that are able to detect the issues that they are interested in?

I have my doubts.

I know NH4 is often used up very fast, before we have a chance to measure it in a tank. We generally only measure the after math of a NH4 spike. We may add it and observe and test on purpose to see the effects, but we'd almost never see it otherwise and think awww...it's the NO3, because that builds up and hangs around long enough to measure............

Regards,
Tom Barr

 

[Plantbrain]

Okay, phase one and the read is done.
Phase two:

MACY'S NUTRITIONAL ZONES, no this is no where you buy shoes.

This is an excellent concept and one we use to study aquatic weeds.
That plus the abiotic environment allows a lot more understanding about nutrients.

The range above that critical point is a good one to think about.
It allows us a lot of flexibilty in our dosing and maintain and wide range of stable growth.

If things get a little lean temporarily, that's fine, they are all "fat" and have reserves, stretch things out too thin, for too long, you'll get a crash though.

Generally 1-2 days is a good time frame there before you have to worry too much.

In figure 5, if you added a noxious pest algae, the curve would shoot up very very fast straight up, but max out at say 20% of the growth rate and then flat line or decrease near the end.

Most noxious pest algae fall into that group.
Bryopsis and others are more like the larger macros and present selectivity issues however. Herbivores/hand removal etc.

Now look at figure 7, think about the push pull effect with NO3 and PO4.

Does it make sense to severely limit NO3 or PO4?
Or should be have some of each in a good ratio that's non limiting?

Are we really limiting the noxious pest algfae or are we seeing secondary impacts/effect that we missed prior?

Is dosing KNO3 as a source of NO3 the same as fish/critter waste that starts off as organic N in food, then fish waste as NH4, then after bacteria or perhaps directly uptake at low levels, by macro algae the same as NO3 from an inorganic source.

I'd have hard time arguing that is was the same, I'd suspect most folks would as well.

So adding NO3 is not nearly as evil as many assume.

Nor is adding PO4 at low levels.

I've not tryed to power through the upper ranges, 0.5ppm or higher really sent the tank's off the deep in the test I've done.

I have more tanks to play with now and can run more extensive testing though as well as a large source of tank grown macros.

I know "how", I want to know "why"

Regards,
Tom Barr

 

[Plantbrain]

Phase 3,

Take a look at figure 9 ands 10 now.
These show growth trajectories for two types of nutrients.

Let's say PO4 and NO3.

Which graph depicts NO3? 9 or 10?
Probably 9. Ask yourself why.
What is critical to structure and uptake in a macro/plant?
Enzymes. PO4 can be added rapidly(minutes), but it takes time and a lot of N to make the enzymes.

Figure 10:
PO4 generally has a less pronounced effect on both Freshwater and marine plants. It can dramatically reduce uptake of NO3 if limited strongly, but the recovery is much better than NO3.

Figure 11, this shows a nice example of how stats can illustrate a nice optimization model for a Nutrient. NH4 is not a good thing to add to any aquatic system though.

Tiny low level steady amounts are fine(fish waste etc).
The system can absorb and assimilate that rate of NH4, but any system can be overloaded with too many NH4 producers and crash and have serious algae outbreaks.

So adding more critters to make up for the NO3 or PO4 to the same sized tank is often a recipe for disaster.

Better to have too little there and then top off with PO4/NO4 salts in a routine consistent manner.

Figure 12 is a useful figure conceptually.
We can applied this to many things in plant science.
Dr Silk is one of the top people in this area.

As we apply this model through time, the growth of the plant, or the leaf or the individual cell changes.

Now we are getting somewhere.

Give these concepts some thought.
Take a look and think about the focus, growing macro algae optimally.

Put aside the fears and assumption you might have and see if they hold true by setting up an experiment the test these hypothesis within the context of a horticultural system with the critters.



Regards,
Tom Barr

 

[piercho]

This was useful to me and has made a start in clarifying some half-baked notions I have about growing algae and uptake. But it raised some questions for me.

1. I'm not sure why a plant has "luxury uptake". Is the plant taking up a nutrient that is not currently needed for cell division/metabolism and storing that nutrient for a time when it may not be abundant?

The following questions have to do with optimizing uptake in a plant filter for a tank growing stony coral. My assumptions are that dissolved organic and inorganic phosphate should be kept as low as possible, uptake of metals that may accumulate in reef aquaria (ex: Cu) by plants should be optimized, most algae growth in the system should occur in the plant filter, and the tank water column should be as oligotrophic as achievable.

2. If you follow the formula for a growth medium but leave out PO4 and the metals you'd like to limit, I take from the article that this should encourage higher growth rates than just using KNO3 alone. For instance, you could use Guillard's formula for a basic ratio, but omit the NaH2PO4 · H2O, CuSO4 · 5H2O, ZnSO4 · 7H2O, and CoCl2 · 6H2O.

3. Assuming the plant filter is a separate tank from the main tank, and you are dosing nutrients into the plant filter, does stopping the return pump for a period (1/2 hour) during dosing help to optimize uptake of the nutrients in the filter and reduce uptake in the tank?

4. From your comments, I am thinking automated, regular, multi-daily dosing of nutrients using a peristaltic pump is preferable over manual dosing, given that many of us have jobs and lifestyles that prohibit routine manual dosing.

 

[ChloroPhil]

Hey Tom,

I was wondering when you'd show up here. How've you been? Any updated pics of your tanks not on barreport?

Regards,
Phil

 

[Plantbrain]

I've been here quite some time(years).
Intermittent poster


I have my runs so to speak when I have time and have done something that can help the hobby specifically with aquatic plants, FW or Marine.

Regards,
Tom Barr

 

[Plantbrain]

Here's some macros I've been working with in a display tank:

Now, it's your turn to figure out what it is.
hehe

Regards,
Tom Barr

 

[ChloroPhil]

Bossiella sp.

Will Cali let you ship macroes across state lines? There aren't any vendors in NC that I know of which will sell macro for less than an arm and a leg if it's not the usual grape Caulerpa. I know you've got plenty of C. taxifolia and other stuff floating around out there...

Have you finished the PhD yet? I've got my sights set on your Alma Mater, UF for mine. Either that or U. North Texas to work with LAERF.

Regards,
Phil Edwards

 

[Plantbrain]

<a href=showthread.php?s=&postid=10153113#post10153113 target=_blank>Originally posted</a> by piercho

1. I'm not sure why a plant has "luxury uptake". Is the plant taking up a nutrient that is not currently needed for cell division/metabolism and storing that nutrient for a time when it may not be abundant?

Following that line of reasoning, why might you have "fat" and starch storage? Same thing with plants.

It takes up more than it needs for growth.

Thus adding more nutrients does not increase growth rate but the nutrients are still removed and taken in by the plants.

The following questions have to do with optimizing uptake in a plant filter for a tank growing stony coral.

My assumptions are that dissolved organic and inorganic phosphate should be kept as low as possible,

Why?
What are you basing such an assumption upon?
Natural systems?
Aquaculture systems?
How was the PO4 measured?
Was there a size fraction filtration done prior(inorganic vs Organic)?
Often, a good test/study will do this, but...........this still does not give fair weight........................

We need to also add the PO4 locked inside the macro algae, the corals themselves, that fraction can and is rapidly recycled and you might never test it and assume that since there is none in the water column................


You assume that they do not have nor store it internally.

Basically, that water test does not measure what PO4 levbels are required internally for optimal growth.

Same deal with Freshwater macrophytes. When they measure the water, they also measured the PO4 locked inside the phytoplankton, but did not add the macrophyte PO4, so this skewed the data to produce a correlation for more PO4= phytoplankton instead of no correlation.

Phillips et al, 1978 made this mistake.

Coral and macros define the system in most cases, not the water column nutrients.

Big paradigm shift in the thought process.

uptake of metals that may accumulate in reef aquaria (ex: Cu) by plants should be optimized, most algae growth in the system should occur in the plant filter, and the tank water column should be as oligotrophic as achievable.

Why?
How can you have both?
Plants need a fair amount of N, if there's none there, how can they grow and remove the NH4/PO4 from the system or trace metals?

There's a trade off with low nutrients/limiting nutrients: it is limited macro growth.

It's our assumptions that are the barrier, not the system or method.

Most aquarists limit themselves with such dogmatic close minded approaches that do not attempt to learn new things or question the hypothesis or attempt to falsify it.

Heck, prove it to yourself!

If you are unwilling to do it in the sake of research or to improve the hobby/horticulture/aquaculture, the voice of ignorance is hardly a supportable defense.

Please note, this is not directed at you personally, I'm talking about hobbyists in general, they are very willing to accept everything that's been said, and not question of test their hypothesis.

I suggest folks try it for themselves, set up a decent test model and try it and see.

2. If you follow the formula for a growth medium but leave out PO4 and the metals you'd like to limit, I take from the article that this should encourage higher growth rates than just using KNO3 alone. For instance, you could use Guillard's formula for a basic ratio, but omit the NaH2PO4 · H2O, CuSO4 · 5H2O, ZnSO4 · 7H2O, and CoCl2 · 6H2O.

Well yes, if you assume you are not limiting the growth of the macros with low PO4.

If you have say 0.5ppm of PO4, let's say Organic and some inorganic, and you want it to be about 0.1ppm PO4 Inorganic PO4, perhapos this is already fine, the other 0.4ppm is not availalble.

But perhaps it's 0.4ppm Inorganic PO4, and then such a medium added would help to draw the PO4 down and keep it low.

The real issue I have here is the notion lower is better, absent etc........... no, it's not.

You want a range for each nutrient, not absolution, you can try, but you will have nothing but troubles getting that.
Some say that's what they have, I wonder though..........test methods etc often can skew things a great deal.........you might think that is what's going on, but how can it be if I'm adding 0.3ppm 2x a week of PO4 from KH2PO4 and have no issues and better growth of the macro and coral?

That just falsified the notion/hypothesis.

3. Assuming the plant filter is a separate tank from the main tank, and you are dosing nutrients into the plant filter, does stopping the return pump for a period (1/2 hour) during dosing help to optimize uptake of the nutrients in the filter and reduce uptake in the tank?

Some, sort of the batch denitrifyer approach.
But you lose growth as the boundary layer issues around the leaves and the differing levels/concentrations of nutrients change.

Plants like steady stable nutrient levels.

Varying them does not help.
The real question you want to ask here: do we even need such low levels of NO3, Fe, PO4?

That's the starting point, not all these assumptions that have not been tested..............

4. From your comments, I am thinking automated, regular, multi-daily dosing of nutrients using a peristaltic pump is preferable over manual dosing, given that many of us have jobs and lifestyles that prohibit routine manual dosing.

Automation adds it's own hassles and trade offs, personally, I'm much better than most automated heehaw devices, steady good consistent care for your tank goes a very long way.

Dosing daily etc is fine for some folks.
I think 2-3x a week is decent and mangeable.

We fed the tanks that much in most/many cases.

I do like to leave for the weekend etc and take a day off away from the tanks etc.

Again, this gets back to the assumption, do I need to walk the razor's edge nutrient ppm wise?

I doubt I do.
I see little evidence that it is required.

So that solves 90% of the issues for me.


Regards,
Tom Barr

 

[piercho]

Thanks for the time it took for such a detailed response.

 

[Plantbrain]

You are on the right track.
Question things.

Basic questions are often best and when we have apparent conflict in the data/observations and applied research science, it's generally a good time to go back and re evaluate things.

Are the assumptions valid and seem good?
Can we test them?

In most case, yes, we can.

Regards,
Tom Barr