# Just got Diana's Book! re: Allelopathy



## Franco (Jun 25, 2010)

I got my copy of Ecology of the Freshwater Aquarium last night in the mail and read it cover to cover in one sitting. I loved how it was formatted in a way similar to a scientific journal article because I am used to reading them after 5 years of biology and ecology courses.

I found the chapter in allelopathy a real surprise but very interesting. I worked for the Iowa department of natural resources for a while in the Aquatic Nuisance Species unit so I am really curious about the application of native allelopathic vegetation to control invasive species. Since Eurasian watermilfoil is allelopathic to algae, I wonder if we could find something to fight back at the Eurasian.

I've noticed that water bodies with the native Northern watermilfoil are often the majority of the vegetation and are extremely clear (low phytoplanton counts) so it is possible that they use allelopathy as well to inhibit other plant growth. I have seen the Northern and Eurasian in the same water body growing intertwined but the Eurasian always has much less biomass. This could also be because they Eurasian was poisoned out at an earlier date and it just on its way back.

I've also noticed that Vallisneria americana does grow well with other plants here in Iowa waters. It stays stunted and infrequent unless there are few other plant species in the vicinity. This could be the result of allelopathic interactions with other plants but also that Vallisneria prefer good water quality which is a rare commodity in Iowa. Where it can grow well is probably too nutrient poor for the more common Iowa aquatic macrophytes. Carp love to munch on it too so that probably doesn't help.

Muskgrass or _Chara spp._, a common multicellular algae in Iowa waters, smells like garlic or onions when removed from the water and not even carp or Canada geese will touch it. Is this scent or (in the water) flavor a form of allelopathy?

Has anyone experienced what they expect to be allelopathy in their tanks and if so what kinds of flora and fauna were involved?

Thank you so much for the book Diana. You finally explained to me about aquatic ecology what 2 limnology, a microbiology, an aquatic ecology, an aquaculture, aquatic insect ecology, and 3 fisheries biology courses could not. I'm going to recommend your book to old professors and bosses ASAP.


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## Diana K (Dec 20, 2007)

I think allelopathy in an aquarium is hard to prove, except in carefully controlled set ups with a lot of similar set ups with just one variable. And that variable might be the introduction of just the allelopathic agent as extracted from plants. 


There are too many variables in most aquariums to say that a particular plant has died, or fails to thrive specifically because of allelopathy. 

Light (Duration, intensity, wavelength...)
Nutrients (couple of dozen elements that plants need are in variable supply in most aquariums, not under good control)
Carbon (yes, it is a nutrient, but usually treated as a separate need from 'fertilizers')
Temperature
Predation (as you note- certain species are eaten by fish, and others are ignored- if a plant disappears in the tank how do you know the fish did not nibble it to death?)

When you see a tank with only one species of plant what really killed off all the other plants?


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## aquabillpers (Apr 13, 2006)

Here's a link to a long thread on allelopathy at Tom Barre's site, from two years ago.

http://www.barrreport.com/showthread.php/4355-Cryptocoryne-Wendtii-and-Allelopathy

Most of the posters to it were anti-allelopathy, in planted aquaria at least.

Bill


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## Franco (Jun 25, 2010)

About a week ago I moved my water lettuce from the indoor, very low light betta bowl in my living room into 2 pico ponds on my deck. It melted within 2 days in the pico planted with val americana and stayed the same in the pico with an amazon sword. Both pico ponds get the same amount of light and have the same substrates, they only difference is, one has Val and the other doesn't.
I moved the now dying water lettuce back inside after I checked the book and it says under the allelopathy chapter that Vall is damaging to water lettuce.
It could just be that the high increase in lighting burned the lettuces but it is also possible that a 1/2 gallon container heavily planted with Vall might have built up allelopathic chemicals enough to zap some baby water lettuce. 
Impossible for me to prove but an interesting possibility.


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## dwalstad (Apr 14, 2006)

Franco said:


> IMuskgrass or _Chara spp._, a common multicellular algae in Iowa waters, smells like garlic or onions when removed from the water and not even carp or Canada geese will touch it. Is this scent or (in the water) flavor a form of allelopathy?
> QUOTE]
> 
> I would think so. After all, the only reason that plants produce allelochemicals is to protect themselves from being eaten by geese and carp, or taken over by algae and competing plant species _in their native environment_. Plants can't run or fight back. Their only hope for survival is to produce allelochemicals.
> ...


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## Diana K (Dec 20, 2007)

Burned water Lettuce may scorched white in the mid leaf region, or the leaf tips are tan and dried up, depending on how great a change in light. I have seen the tan dried tips when it gets too close to an aquarium light and I think this is a heat reaction, not directly related to too much light too suddenly. I have seen the white leaf blotches when I have moved it from indoors (roughly 2 watts per gallon, but of course floating right under the light) to the pond (Lots of morning sun, then dappled light from trees the rest of the day). 
I have seen a combination also when I have moved it to my pond on a hot day, and it lands in the sunniest spot when it was used to aquarium light. 

I do not have any Val in the pond. There is some (several species) in a few aquariums, maybe I had better see if Water Lettuce will live in those tanks!


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