Nearly two months with the seagrass now

[Plantbrain]

Hmm.. well five days into mega aeration via skimmer and I have no skimmate to speak of and some nice lookin grass. It has definitely grown faster this week and there are a few new plantlets poking up out of the ground. I also didnt have to dose bicarb the last two days because Alk held stable overnight. I imagine this indicates the plants have effectively switched back to CO2 over bicarb molecules as a C source?

Ahh, you learned a valuable, yet very simple and easy lesson.
Plant biomass is mainly Carbon.

The focus should be on the plant's needs.
Your conclusion is correct and the diatom issue is also.

However.... this has triggered a small brown diatom-looking bloom in the tank. Its not choking the grass or anything on such a scale but small patches of it are showing up on the glass. Perhaps I need to rethink my dosing schedule as faster growth = faster consumption of N and P. What do we think?

The diatom bloom should be temporary.
Only attacks the glass.
As PO4 declines more, the diatoms should back off.
I don't mind some soft glass algae once a week, but it can become annoying.

Not sure about the limits and constraints of the diatoms just yet.
I know I can add PO4 and induce them.
I also know they come mainly in the start up phase but unless you add PO4 or neglect the tank, they are not an issue.

I have the answer for you on the plants, why the diatoms?
algae prefer CO2 as well.

Changes in the CO2/NH4 content let the algae "know" => sets off a series of inducible genes in a spore/cell to grow.

When CO2 goes up and NH4 goes down, that means no one else is around these are good environmental signals(like rain in the desert, warmer weather, longer sun light day lengths etc).

Thus a good time to grow if they can get a good jump on the competition.

CO2 and high light can also drive photorespiration and many algae have a rough time with this, plants are not as impacted, but their growth rates can be reduced by this process.

One more thing - an article I found on stargrass suggests that they prefer glutamic acid to potassium nitrate as an N source. (??) Maybe this is why my B vitamin mix had an impact, I think there is some in that formula.

Perhaps you mean glutamine?
NH4=> via GS/GoGat=> Glutamine
NO3 needs 8 electrons to be reduced to NH4.
While plants perfer NH4 over NO3(in general), so do micro algae.

This NH4 means a lot more to a little single celled algal spore vs a huge billion celled weed that has plenty of N reserves for NO3 transporters. Basically the plant has the activation energy required to use NO3, wereas an algae spore does not.

Also, the NH4/will be far more toxic and GA may degrade into NH4/NH3, you can add the relatively benign NO3 without much issue, NH4 is playing with fire.

I suppose other forms, and you can also chelate NH4 as well, but then you lose some of the efficacy that you are trying to provide the weed with in reduced energy.

Plants, all of them and algae leave the ETDA, Gluconate etc out side and need to remove it from the chelator prior to bring it into the cell.

The stronger the bond/complex, the less the plant gains with a more preferred form.

There are trade offs.

PS: I'm in a terrible mood.. anyone who thinks science isnt cut throat should shadow me. We got scooped by another lab that published in Science this week...... There is however a cool little article on zooplankton in the same issue. (See how I can seque between marine hobby and the real world? )

>Sarah

Sorry.

Does not degrade the research you have done. Only confirms it.
Many of the things I deal with transcend the hobby and into my field and vice versus.

I kill and grow weeds(yes, I get paid very well to grow plants), I have more funding than I know what to do with. If I have independent confirmation, super. Simply means I don't have to answer that question, on to the next question........look at the positive side....

Don't get down, you are the golden goose..........cook up something new.

A dozen more questions arise anytime a new piece of research is done. I'd look there for any good scraps.

Also, get good at pilot test. They are guesses, but don't dismiss nutty ideas either. They are often the ones you do not expect to work but often do. Quite humbling.

Regards,
Tom Barr

 

[Samala]

"Inducible genes".. now we're talking my language! Thanks for the thoughts.. the points on NH4 accessibility is especially well taken. I'll be screening that vitamin solution from now on for this kind of fall out.. probably just cut it from the list for a while to see an effect on the tank. Thoughts on diatoms are great, quite logical, I feel I should have realized them myself.

Oh and thanks for the encouragement on research. You're right, more questions, that's the game. Still, as I hear, 'publish or perish'. Thanks again Tom!

>Sarah

 

[Plantbrain]

NH4 transportors are poorly understood, but it's my understanding with the transportors that have been studied, that NH4 is not inducible(constitutive-eg always produced whether or not the substrate, NH4 is present), wereas NO3 generally is and is much more understood, likely because you can inhibit it by adding NH4.

Plants are lazy like us, a free meal is always welcomed, if there is a little NO3 (say 1-2ppm of NO3) and not much NH4 around, then they will induce one NO3 high affinity transporter.

If there is a stable high level of NO3 (say 15ppm) and not much NH4, then the weed will induce a low affinity transporter.

Some plants have dual functions on the same NO3 transporter even. That's pretty cool.

So the NH4 will be removed at a fairly steady rate first, then when it gets pretty low, NO3 transport begins.........if you maintain a stable level of NO3, then the plants will continue to use the enzyme transporter.

Now if you add pulses of NH4(messing in the tank, poor environmental conditions, neglect, uprooting, cleaning filter etc) then you freak the plant out.

When the NH4 is present, often times the plants will inhibit the NO3 and sometimes chew those enzymes up.

So if NH4 is kept to a minimum, NO3 maintained at a stable level(which keeps the NO3 inducible transportors going at full blast), then you have the best growth without noxious algae.
Some transition peroid is required but after a week or two, things should settle down and get going well.

Micro algae can respond very quickly, a big billions celled plant does not. Micro algae have a much higher surface to area S/A ratio so they are better at less, plants can take up larger amounts.

Think about a mouse and an elephant for a comparison.
Both are herbivores. One reproduces fast, the other slow, but has a much bigger belly and ain't something you keep in your home. You need more food and room for it. Mice do not live long, elephants as long as us. Plants and microalgae are very similar tot his comparison.

Publishing (volume is the main thing) : get as many papers as you can. Even little ones etc, side projects, collaborations, get your name attached, work together with other folks to do this. Ask Bubba to help with the GIS, or Protein columns while you do the stats, general overview/writing, grant submissions or what have you.

Heck, if was just one person, it'd take forever.
Smaller chunks, answer issues important to what the grant committees want.

Teams work well for this reason.
Science, business, sales, this hobby etc, it's still all about people and helping others.

Regards,
Tom Barr