f1ea

Great tank Jim. I like that it doesnt 'try' to look like a high tech tank.
Very healthy plant growth and even better how low maintenance it is... great Ludwigia and Swords; swords have only done well for me on natural tanks, everywhere else they struggle.

Nice discussion too!

Dustymac

Thanks! I struggled for years to grow plants in my fish tanks. It wasn't until getting Diana's book that I started to understand what I was doing wrong.

Jim

Dustymac

Phil,

Localized allelopathy seems fantastic to me. It would require the plant cell to detect the attachment of the alga on the outer cell wall and then bore a hole into the the anchoring algae cell to inject the toxin. I've never heard of any cell, plant or animal which has this capability.

Then, for the toxin to poison the rest of the algae filament, it would require an active transport mechanism from the anchoring algae cell to the rest of the cells down the line. Since algae filaments are only one cell thick, this is equally fantastic. Even if we assume there is some sort of diffusion between algae cells, permeation would be slow and hair/beard algae would appear to have white roots as it starts to fade. I've never seen this.

As to the slouphing off of young plant cells, I can't find anything on the net or in any of my literature to suggest plants have this capability. From what I know and what I can research, plant leaves grow to a certain size and then stop. No further cell division takes place.

Finally, spore creation would be exascerbated by CO2 injection since algae feed on CO2. If someone wanted to reduce spore production, the last thing you would do is add something to the water to help the algae grow. If you didn't add CO2, you might be able reduce spore concentration through heavy water changing. Given how short are some algae reproductive cycles, I suspect no one changes their water that often.

You still haven't addressed my theory that CO2 injection hastens the depletion of a limiting essential nutrient which gives appearance that it's hurting the algae.

Jim

Philosophos

Why would it require this? Other chemical toxins don't.

Viruses do it all the time. You'll find ID proponents trying to use it as irreducible complexity while simultaneously ignoring flagellum. That's besides the point, though.

Why? Wouldn't detachment be enough to remove the algae from the plant?

I'd assume you'd need a microscope to observe the death of a couple of cells. I'm not speaking of long strands of algae here; I don't see plants recovering from that. This is about establishment on what would be a microscopic level.


What I'm referring to here is the fine cuticle that exists on submerged macrophytes; not the upper epidermis. Submerged plants have a reduced cuticle, but it is definitely still there.

Algae require far less CO2 than SAM's. If algae growth is not favorable when SAM's are under optimal conditions, especially ones that push for surface space to reduce light underneath. It may be possible that many species of algae has evolved when CO2 levels are low and NH4 levels high simply because it is a point that frequently correlates with macrophyte decline.

The fact that EI dosed tanks test out at nonlimiting levels of nutrients constantly without inducing algae is very strong evidence for this. I pointed it out in my last post. Algae is not rampant in many tanks where Sears-Conlin dosing exists with PO4 added back in, and non-limiting CO2.

-Philosophos

Dustymac

If you rule out secretion into the tank water, how else is the toxin supposed to poison the algae cell? Teleportation?

Richard Dawkins aside, you realize the difference in scale between plant cells and virii? Or are you suggesting plant cells foster their own algae-attacking viruses which overcome algae defenses? Evidence please.

That's not the way algae dies. Hair/thread algaes discolor when they spill their chloroplasts but maintain structural integrity, going through a pale phase before breaking up. Besides, I've seen millions of algae hairs but can't remember one instance of noticing them floating un-tethered about the tank.


I have a microscope and have viewed algae countless times. It's really quite interesting. When over a bright field and in a well slide, the algae cells start out growing at a rapid rate, no doubt in reponse to the intense light. Then in a short time reproduction stops - some essential nutrient has been depleted, likely CO2 but impossible to tell for sure - and one by one the cells start to die. I think of the cells as exploding but that's not quite correct. Anyway, the contents of the cells spill out into the water where bacteria are waiting. Eventually the algae filaments are reduced to mush interspersed with bubbles of gas trapped under the cover glass which I presume to be CO2 given off by the bacteria. It's not pretty.

Yes, but I can't find any evidence your slouphing takes place. As I mentioned before, if sloughing or shedding was ocurring, old leaves would look like young leaves. Is it too much to ask for a reference?

Yea, but you are not inhibiting algae by adding CO2; you're encouraging it to grow right alongside the plants. This leads back to my theory that adding CO2 increases the whole metabolic rate of both plants and algae until a critical nutrient for algae growth is depleted. As long as that nutrient can be found in the substrate and not the water column, the algae will perish and the plants will thrive.

-Philosophos[/quote]

I don't know what Sears-Conlin is but I'm guessing it covers Copper, Manganese, Boron, Zinc and other elements crucial to algae growth?

Philosophos

All it needs to do is poison the cells in proximity with it, not all the way up the chain.

Notice the part where I said, "but that's besides the point." I figured you'd want to know an exception if it existed.

The concept was actually outlined most popularly in "Darwin's Black Box" which predates Dawkins' celebrity status.

Again, we're talking about working on a microscopic level; it would prevent attachment, not allow long strands to grow. We're talking about a point at which the toxicity would have to be high enough to prevent reproduction. You'll find most places that make mention of this concept quite specifically state that this is a difficult hypothesis to test, and precisely why it is not considered fact.

Have you viewed algae failing to attach its self to a living leaf? This is something that would happen and need to be observed in situ.
The cuticle on plants is produced by the upper epidermis; it's a waxy deposit and the result of cellular metabolism. The loss and regrowth of it would not make a plant look new. They even contain allelopathic compounds within them at times. Pick up any book on plant biology, or if all else fails look to wikipedia if you want to learn about the cuticle of a plant. Since I have a feeling you'll want a specific source, this is one that everyone can just click the button and look at, though many others exist: Handbook of Plant Science,V1 pg 70

It specifically talks about waxy cuticles being secreted by tubules in the epidermis

But that's exactly it; a very large number of hobbyists dose to nonlimiting nutrient levels including both macros and micros. You can even run an NH4 free Hoagland solution and maintain those levels without inducing algae simply through excessive nutrients. Your concept is one that was very strenuously examined by Tom Barr in a specific effort to show that nutrient limitation is not necessary to eliminate algae as any real issue in a planted tank.

You'll also find that your theory doesn't match up with the adaptive nature of algae, either. Algae is not just a handful of species; for any set of nutrient, light and CO2 conditions you can lay out that macrophytes can survive, there is an algae to adapt to it. Even the cleanest tanks are never algae free, but less competitive forms of algae can be kept in check. If you reduce one element, you change the point of equilibrium and the algae species or growth pattern shifts. A number of species of algae will even manufacture different pigments within themselves to better match the wavelength of light that they are receiving. Audouinella would be a prime example of this carotenoid/chlorophyll shift.

The paper by Paul Sears and Kevin Conlin is one of the best known in the hobby. It's refuted in terms of it's concept of algae control through phosphate limitation, but it's the base work that has been built upon for a lot of the dosing methods found in the hobby.

-Philosophos

Dustymac

Let's see, you can't explain how localized allelopathy is supposed to work, you can't point me to one reference supporting your slouphing theory, you can't specifically address my theory other than to say it doesn't match, you have a new guess where something prevents algae attachment, presumably by magic, and for everything else you say science isn't up to the task.

Let me guess; this is your idea of fun!