[APD] Re: The why of the Barr method

[Tony Eales <s328962 at student_uq.edu.au>]

Great topic. I'll be most interested to see everyone's contribution.
I think the method works for a number of different reasons but when it 
comes to epiphytic algae I have a theory. Plants have been battling algae 
much longer than we have. Why aren't plants in nature covered in algae? (I 
know they sometimes are but they are just as often not).

I think you're too quick to rule out allopathy. I agree that the idea that 
plants are pumping allopathic chemicals into the water column or substrate 
is probably incorrect however at the cell surface where algae are trying to 
attach things may quite different. I think it is similar to the experiences 
of some where previously benign algaevores and detritivores like SAEs and 
snails turn into ravenous herbivores on our delicate plants. Complex 
allopathic chemicals, whether they deter herbivores or  epiphytic algae are 
expensive to produce for the plants. If the plants aren't in top health 
they are too busy just staying alive that they cannot use their complex 
evolved responses to combat attack.

I realise this doesn't account for getting rid of green water or algae that 
don't/aren't attached directly to the plants but I think this is one of the 
things going on.

Tony Eales
333 Whites Rd
Lota, Brisbane 4179
Ph (07) 3365 6958
Home (07) 3396 8496

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