Re: [APD] RE: Why algae don't grow and plants do under non limiting conditions

[Thomas Barr <tcbiii at earthlink_net>]

While we can provide stable light, CO2, nutrients etc, generally, the environment is variable, the nutrients are high in the spring turnover(Diatoms), low in the mid late summer(Cyanobacteria), light is higher/lower as the seasons change/leaves grow on terrestrial plants and block light, nutrient input from terrestial sources durning spring melt, temp changes.......

Many things that have little to do with our tanks.........
They grow in specialized niches
But for nutrients changes, N will make the largest difference(behind light and CO2) and is often limiting in FW systems. So it makes sense on a broad scale for various algal types as a trigger and lets the alga know if there is comptetition in the form of a stable autotroph already present and established and/or a stable bacterial population (in which case another type of algae will grow). 

In terms of evolution, I think algae are far from weenies. They can live in more toxic places, live on far less, handle more mechanical shock than any plant, live higher, lower, colder, warmer, saltier, darker, there is even a human infestation form that gets on the legs. I've seen some cases of it on patients in West Africa. I'm unaware of any higher plants that grow on us. 

Regards, 
Tom Barr

  

-----Original Message-----
From: "S. Hieber" <shieber at yahoo_com>
Sent: Apr 6, 2005 6:05 AM
To: tcbiii at earthlink_net, aquatic plants digest <aquatic-plants at actwin_com>
Subject: Re: [APD] RE: Why algae don't grow and plants do under non limiting conditions

This is the best hypothesis offered so far. I suppose it is
easily enough related to stagnant ponds and puddles
developing lots of algae and few plants.

Not outcompeted by plants for NH4, but, continuing along on
the teleological track, algae merely resign the contest.
Although it's not clear why algae would decide to resign
when the energy demands are higher. Makes them seem like
darwinian weenies.

sh
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