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Re: plant vs algae
- To: <Aquatic-Plants at actwin_com>
- Subject: Re: plant vs algae
- From: Thomas Barr <tcbiii at earthlink_net>
- Date: Fri, 01 Mar 2002 10:38:13 -0800
- In-Reply-To: <200203010343.g213hhw16468 at actwin_com>
- User-Agent: Microsoft-Outlook-Express-Macintosh-Edition/5.02.2022
> Larger algae out compete smaller algae in nature.
I forgot to add something here ==> ***When there's more nutrients*** in this
particular case(eutropic condition). Smaller algae(cyano's/picoplankton) out
compete larger algae(diatoms) when there's less nutrients.
Lake Victoria use to have a large diatom population but all the input of
nutrients from human encroachment/burning/agriculture etc has added more
nutrients(too much) and this has removed all the silicone that diatoms need
to build their shells(frustrals). When the diatoms die, the shell falls to
the bottom but Si dissolves very slowly. Relative to the N and P inputs the
amount of Si in the water has greatly changed.
A few plants seem to need Si, such as Equisetum sp(horsetail, Scouring
This has caused a shift to cyano's bacteria and other smaller algae.
This is another system where the reverse _seems_ true if you only consider N
and P. There are other requirements in nature and many cases need to be
It does lower diversity(as most human activity seems to do) and this effects
the entire food chain.
While Lates sp(Nile perch) introduction in the 1980's for food has done a
great damage to the native fishes of Lake Victoria, eutropication has wiped
out virtually all of the lower portion of the lake to anything but bacteria
by turning it anoxic. All the desmersal Cichilds are pretty much gone. The
rock cichilds are there but greatly reduced(Lates food). The light is far
less able to penetrate into the deeper water(this heats the surface waters)
and reduces the area for algae production. The extra heat at the surface
also stratifies the water column that used to diffuse and mix into one that
doesn't. This means less food for the algae and potential nasty upwellings.
Also means less places for the Lates sp and less fish for the people in the
area. I've seen the Lates sold in markets in the USA locally, Victorian
SeaBass it's called. Ran about 10-12$. Oily texture somewhat like the
Chilean Bass which no one should buy(It's more a true Antarctic fish) as
it's being quickly decimated from overfishing. The great lakes of Africa are
the Rainforest of the FW aquatic fish world. They are huge and they are
being loused up fast by humans. Oceans are next(or already
It's difficult to predict what will happen, but I'll tell this: it's not
going to be good. Cyano bacteria soup anyone?