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Re: Knowledge extrapolation

Ed Hengel asked:


> My question then
> would be: am I making a correct assumption as to a very possible
> outcome, i.e. a pea soup lake, or am I way off base?

I don't look as this as being *way* off-topic, because the diversity and 
natural behavior of wetlands, ponds and lakes is something I'd like to 
be able to emulate in my aquaria.

Extrapolating from aquaria to the scale of a pond, lake or wetland is
inherently risky.  There are large differences.  Aside from the obvious
difference in scale, lakes are generally much more biologically diverse
then aquaria and provide numerous divergent settings where different and
often complimentary influences are at work while aquaria are more
homogeneous; lakes support processes that operate over periods of seasons,
years and even decades while in aquaria we usually limit things to periods
of weeks.  Certainly there are other differences, but these are the big
ones from my point of view. 

One of the sweeping generalizations about lakes is that (all else being
equal) the longer water resides in a lake, the cleaner the water gets. 
This illustrates the great differences between natural water bodies and
many aquaria. 

Aside from generalizations, it's impossible to comment (well, accurately, 
anyway) on conditions in your lake, because there's a great deal of 
variation in the hydrology and ecology of different lakes.

All that aside, I think your belief that introducing carp to the lake
could result in pea-soup conditions might be right, at least in the 
short term.  Their dining on the higher plants would cycle nutrients back 
into the water where it becomes accessible to algae.  Also, carp dig 
about in the bottom sediment and this not only muddies the water but 
can also resuspend nutrients that were previously sequestered in the 
bottom sediments.

In a longer term, if the lake is sufficiently deep and other conditions
are favorable, then the nutrients released by the carp's hard work might
eventually end up locked away in deep bottom sediments so that after a few
seasons the lake would clear up and there would be fewer macrophytes.

At any rate, I don't think that carp should be introduced anywhere without
serious consideration of the possible consequences.  Among other things,
some introduced, supposedly triploid carp have turned out to be fertile. 

I suggest you look for other similar lakes in your area where carp have
been introduced and see what happened there.  Also, there may be county,
state or (in some cases) federal agencies that can offer advise.  There 
may be faculty at local colleges and universities that have special 
interest in lake management who would be willing to advise you (they may 
or may not charge for their advice).  And of course, there's always going 
to be a consultant willing to take your money.

If your neighbors view "water weeds" as a real problem and this is a
problem that has increased over time, then it might be better in the
long run to indentify and fix the root of the problem than it is to merely
control the weeds with carp or other artificial means.  Fixing the root of
the problem may mean doing something like sewering neighborhoods in the
watershed, or trying to better control land use or runoff from urban areas
or agricultural land in the watershed.  That usually means that you will
need public consensus and political clout.

Roger Miller 
In Albuquerque, where its about 50 miles to the nearest natural lake.