permaculture

[<permed@nor.com.au>]

>I'm thinking of throwing some zebra mussels and eurasian millfoil ( the two
>big invasives of Lake Champlain) into my little yard pond just to see what
>happens.... I figure since they can't escape to the broad lake ( and so what
>if they do, that's where I got them from) I can afford to make a "little
>mistake" - I have a hunch that they will NOT "take over" but will in fact
>reach equilibrium/stasis once the've gotten through filtering the water -
>i.e. once available nutrients diminish, how can their populations continue
>to swell ?

The plants die and release their nutrients back into the water.
I still caution against intentionally introducing rampant floating water 
plants onto ponds especially ones like water hyacinth, water lettuce and 
salvinia.
However I acknowledge these plants do have a place in a well controlled 
and meticulously managed system for water purification where the system 
is specifically designed for continuous and convenient harvest for 
mulch/compost and there is absolutely no chance they can escape into 
larger bodies of water or natural water ways.

Some local friends have a commercial business harvesting rampant floating 
waterplants - contracted by mostly local government and water authorities 
and for private landholders who've received an ultimatum under the 
noxious weeds act (the big dam at Tagari Farm is one such example & a 
costly exercise). These guys compost the harvested weeds and sell the 
compost. 

I have azolla on some of my small ponds of maximum 3-4m (10-13ft) 
diameter so I can easily harvest with a rake or scoop net on a 2m handle 
but would never want to see the floaters take over my big dam. I also 
admit to having a couple of hyacinth plants in a little tyre pond well 
land-locked in the middle of the garden for educational id purposes but 
would not risk having salvinia or water lettuce anywhere on my property, 
not even in an aquarium.
Robyn