Re: NANFA-- tannic type stuff

Scott Davis (
Thu, 1 Aug 2002 13:09:44 -0500

> Maybe they're measuring water "hardness" by solid wastes and garbage.
> were we calling it last week? Allochthonous? ;)

I think that would be called TDS - totally dissolved solids.

That is of considerable importance for aquarists acclimating fishes to their
tanks. For those chemistry-challenged like myself, that is why leaving the
fish in a jar or bucket (or otherwise covered container) and adding a small
percentage of aquarium water at intervals over a good period of time, allows
the fish to make adjustments. (Yeah, sophisticates could use a TDS meter to
see if both waters are similar...)

A week or so ago, this list was talking about allochthonous and
autochthonous waters. I was reminded of pioneer accounts of western streams
with lunker trout piling up in holes almost like cordwood. Those clean,
clear streams were probably pretty short on autochthonous organisms under
the surface for the trout to feed on, but they could have a 100 miles of
prairie or forest to generate insects (the allochthonous stuff) which would
fall into the streams. Certainly a different system from what exists in many
places today.

There are books on the Amazon system and especially the poster boy of tannin
stained rivers - the Rio Negro - which have described the rivers as species
rich deserts. There is so little in the water, assuming that the sunlight
could enter the water, that algae don't even grow much. However this amazing
assemblage of fishes is feeding off of the insects, fruits, leaves,
dim-witted tourists and what-have-you falling into the water. That is where
a lot of the organic material is coming from to start the food chain.

By the same token, look at the picture of a jungle stream side beach. A lot
of times the sand in the beach just keeps running up into the forest. Most
of the real organic content for a rainforest is not in the soil, but in the
plants and the fauna living in the plants of that forest (and a lot of ant
and termite nests in the soil and trees).

There was a Time-Life book on the Amazon (commonly in public and school
libraries) which spun some fascinating stories of how quickly organic
material is recycled there. A latrine is cleared of all material in a couple
of days. It used to be in some cultures that when a person died, the
mourners would leave the body in the forest. A week later the people could
return to retrieve the cleaned bones for proper funerary arrangements.

That is why clear cutting large areas is so devastating - if the trees are
hauled off and the foliage is burned (to blow or wash away), there is little
left for any surviving plants to grow on.

Temperate climates generally have less opportunity for the land to leach and
for the organics to burn out of the soil. It is possible though. The desert
furthest from the Equator (I seem to remember reading) is in Poland. Some
king several 100 years ago, got really annoyed with the locals, and had the
land logged and burned. Sand was what has remained to this day. (Virtually
all of the Mediterranean basin was oak forest a several 1000 years ago. See
what over grazing and a slave based agriculture can do for the land.)

> You can't treat tannins and sediment runoff the same.

Therefore one probably has to treat each area in North America as unique.
Some areas with a lot of rain, sandy soils and pine trees probably will have
black water streams without many nutrients in them.

Others, especially with nutrient run off, may be loaded with organic
goodies. Too much of a good thing, of course, can be worse than not enough.

Some municipal water departments, if they draw from a particular stream,
(allowing for all the garbage water departments add and the occasional ion
exchange which pulls some calcium and magnesium out, replacing it with
sodium) might be able to give you an EPA water content report. That would be
a cheap start to understanding the local water. I'm sure list members here
know of several other sources for water content studies.

All the best!

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