# [Wet Thumb Forum]-Allelopathy - chemical warfare



## António Vitor1 (Feb 2, 2003)

Allelopathy - chemical warfare between aquatic plants -

very interesting article...

tropica site

AntÃ³nio Vitor


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## António Vitor1 (Feb 2, 2003)

Allelopathy - chemical warfare between aquatic plants -

very interesting article...

tropica site

AntÃ³nio Vitor


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## Guest (Mar 7, 2003)

Natural(?) vs unatural(?) system comparsions.
Are these realistic?

Non CO2(no water changes) vs CO2(lots of water changes)?

I'm not sure I got much out of either except what I already feel about allelopathy. It ain't much. 
They might feel it is, an el dorado, I don't think so.

My chairman has listen to me rattle on about it, so has the dept chair, both on the review board for C for AP, the journal Aquatic Botany etc. I'm pretty good at plant metabolism.But none of us think it play a significant role, perhaps a few isolated cases but........ 

In order to explain the observations, something a bit more all encompassing, ubiquitious, able to be given off by many different plant families/species(300+) would have to occur.

A little cyano decline, one species of marine algae, some good work etc, but useful for keeping plants and the reason for plant dominance?

I'm very skeptical. I'd say O2 alone is much more likely responsible for observed effects than anything to do with allelopathy. 
If it happens much, it'll happen in the roots.

Eleocharis sp would be good plants for allelopathy in root-root interactions. Problem is, algae don't have roots, pore water is not water column water.

What good is that?

I think ultrasonic algae control is a much better idea than adding a bottle of plant juice for killing algae. Works pretty good. I think an algae killer for about 50$ could be made that would work on algae but it leaves the higher plants alone. You simply add a small speaker and leave it on. Doesn't bug fish. 

Regards, 
Tom Barr


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## António Vitor1 (Feb 2, 2003)

I think you are right Tom Barr!

Simple experience to prove the importance of O2:

-few plants (or even no plants) 

-water saturated with O2(with a pressurised O2 system)

-every nutrient necessary to algaes in the water... 

...and see what happens...

it would dissipate any doubts about the O2 importance on the aquarium.

Regards!
AntÃ³nio Vitor


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## plantbrains (Mar 11, 2003)

See an APD post I recently put up on Photorespiration.

Been getting progressively closer to proving my notions. Not a lot has been done. But has good applications for other fields in limnology and plant biochemistry.

Regards, 
Tom Barr


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## imported_Allen (Feb 14, 2003)

> quote:
> 
> Originally posted by Van grow:
> I think ultrasonic algae control is a much better idea than adding a bottle of plant juice for killing algae. Works pretty good. I think an algae killer for about 50$ could be made that would work on algae but it leaves the higher plants alone. You simply add a small speaker and leave it on. Doesn't bug fish.


I couldn't help but notice this line in an earlier post so I did a search and hey presto there were some products on-line doing this...

In theory, building this could be as simple as having a signal source, an amplifier, and a transducer... but what frequencies are we talking about? 25KHz? 60KHz? Is the actual frequency important? and at what amplitudes do we have to transmit the ultrasonic levels to be effective?

on a side note... this will probably drive all the dogs in the neighbourhood crazy.

Allen 
============
Allen's Tank Pics.
============


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## wetmanNY (Feb 1, 2003)

...and rid your yard of moles and gophers too. 
http://pestcontrol.netfirms.com/Gopher_control_.htm


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## plantbrains (Mar 11, 2003)

Ultrasonic speakers are used for algae control in water colling towwers, ponds/lakes etc.

It works very well and better than barley, UV etc. 

Modifying those fogging units they sell for 30-65$ to match the frequencies suited for implodision of algal vacuoles should work great for 1000 gallon doen since aquariums have excellent acoustical properities.

I have an ultrasonic algae cell lyser at my lab we use to extract chloroplast etc.

If you want a sane method of algae control that will not effect the plants/fish etc, this is IMO, the best device there is.

Simply toss the speaker in the tank and within 1 week all the Green water and about 2 weeks the filamentous disappears.

The commercial products from the Netherlands start at about 700$US at the moment and are larger suited for lakes etc, but these units use very little energy vs a UV and are much better for algae control than a UV.

A smart company would make such a device by modifying those cheap fogging units.
They'd make a ton of $.

Regard 
Tom Barr


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## wetmanNY (Feb 1, 2003)

Though ultrasound isn't completely unknown to members of AquaBotanic, its application to eliminating algae in aquariums is certainly a fresh one.

This is how a team at the University of Adelaide School of Engineering describes the action of ultrasound: www.mecheng.adelaide.edu.au/4thyearprojects/generalaccess/ project_details.php?prj_id=65&year=2003 - 9k

_Ultrasonic irradiation in a liquid medium has been used for many years to lyse biological cells and release intracellular compounds in the laboratory. Ultrasound spans the frequencies of roughly 15 kHz to 10 MHz with associated acoustic wavelengths of 10 to 0.01 cm.

Ultrasound causes cavitation (bubbles) at weak points in the liquid and grow until they reach a critical size where the surrounding liquid rushes in and the cavity implodes. The pressures in these cavities can reach 500 atmospheres and temperatures of 5000oC with heating and cooling rates of 109 K/s. The lifetime of these cavities is measured in microseconds. The collapse of these cavities creates shock waves that propagate in the liquid medium and generate stresses, which are strong enough to disrupt cells.

It is suggested that ultrasonication could be used for collapse of gas vesicles contained within cyanobacteria (tiny gas filled cavities within cells). This may have the potential to reduce their capacity to float and control their buoyancy thereby reducing their concentration near the surface of water bodies and lessen their growth and survival. Ultrasonication may also inhibit or reduce growth of cyanobacteria through its affect on metabolic processes. Very little is known about the likely impacts, although the potential for impacts upon cells is quite interesting._

This really wouldn't affect the fish, then? Waves of the future!

[This message was edited by wetmanNY on Wed March 12 2003 at 04:17 PM.]


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## Kurt Reinhart (Mar 4, 2003)

I haven't had a chance to read any literature on allelopathy in aquatics. However, I would argue that the rarity of allelopathy is what might make it extremely important in terms of non-native and invasive aquatics and plant community assembly. In general, there is either an arms race between herbivores (competitors) and individual plant species. Thus, it is hard to dramatically effect species that are used to you unless you evolve something very difficult to adapt to (mustards and glucosinolates spelling?). However, when these plants are transplanted into new regions with new herbivores and competitors these chemicals may have dramatic effects because there native species have no history with the coevolution that lead to the allelopathy. The lab that I'm working in has identified some root exudates for spotted knapweed (a prairie invader) that seem to not be produced by any other plants (of those tested). In the plant's native range the other natives are used to it and beat the tar out of it (thus its abundance is low). But in its new range, the plant dominates and the different isomers of the chemical either kill microbes or other plants. The point of this example is that one plant may interact entirely different with different assemblages of neighbors. Thus, I can't not possibly agree with a statement the something isn't important because it isn't always important. For example, Allelopathy may be important in salt marshes but not eel grass flats, mangroves, etc. Thus, in general it isn't important but if you're interested in salt marshes than it is pretty important to understanding that system. 

Dominant plants use an endless array of mechanisms to maintain their abundance. It is great to look for large scale generality but the reality is that are tons of communities each with varying levels of diversity and the interactions involved in assembling those communities is also likely to be diverse. Thus, allelopathy may be rare but still important

Can turtles and plants coexist in a tank?


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## plantbrains (Mar 11, 2003)

I see the same observation with many years of experiences, with all plant type and combinations(around 300 species of plants). If it played a significant *general role*, I'd seen it a long time ago. Or something close.

There may be extremely specific examples but why would a plant excrete something into water where it'd be taken away almost immediately? How does an aquatic plant know how big of a volume of a body of water it needs to "bomb"?
What if the plants live in a fast flowing river?
Big waste then.

Roots in terrestrials is a whole other ball game. Algae don't have roots anyway. There may be root-root plant interactions with aquatics but I've never seen any that would count as "significant" in an aquarium with 300 species. If you have, please let's hear them.

Considering the various aquatic environments and plants adaptations to these environments, allelopathy is pretty shaky stuff. Bromus sp and grass interactions of terrestials I've seen and measured and have friends working on root-root interactions. Namely plants that "defend" a territory. Here, they have much to gain by adding allelopathic chemical and these will not dissipate rapidly.

If it does occur, I'd say it's something that's vestigal from the plant's land ancestor. Eleocharis acicularis would be a good candidate at a community level, but in water, or in a tank, you'll be extremely hard pressed to show this.

Algae are quite different in many respects from plant plant interactions.

I have talked to many plant experts that are at the top of their field in aquatic plants, they all scoffed at the notion of allelopathy. They might be wrong. But I don't think they are.

Turtles can and do exist together in tanks and nature. They exist in my study sites, big ones

Ultrasonics, the effects of fish, plants have been studied in practical terms on lakes and large hard walled ponds.

No side effect etc. 
I have some tanks I can try it out on. But I'd like something a bit smaller than the huge device we have in the lab







Still, it should not take much and also be useful for SW, but not sure about corals/zooxanthellae.

The US does work on filiamentous algae but it takes a week or two longer.

Regards, 
Tom Barr


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