| If you
examine pond water without culturing it,
you'll probably find the protozoa are somewhat
difficult to find because they are not
present at high density. To increase the
protozoa density, make a hay infusion by
putting the water in an open jar and adding
cut dried grass or hay. The grass or hay
should be green when it was cut and dried,
and be free of herbicides and pesticides.
You may also wish to add a few grains of
yeast and a few drops of skim milk. The
sugars in the dried grass or hay and the
nutrition provided by the yeast and milk
provide food for the bacteria in the water.
If the jar is kept at room temperature
for a few days the bacteria proliferate
(and make quite a smell!). The bacteria
are food for the protozoa, so the bacteria
population boom will create a corresponding
protozoan population boom.
Be careful to not add too much hay, grass,
yeast, or milk. This will overfeed the
bacteria and they'll poison the water with
their waste products before the protozoan
population gets a chance to catch up.
Protozoa are oxygen breathers. Give them
oxygen by using a pipette to bubbling air
into the water at least once a day.
Taking samples with a pipette near the
surface of the water, near floating debris,
and near the bottom of the jar will often
give you different types of microzoa to
examine. The hay infusion population will
peak about a week after making it. If you
want to keep it going, get more fresh water
from the original source, add hay, etc.,
and inoculate the new culture with several
pipettes filled from the old culture.
Remember that the hay infusion has a very
high bacteria count. While the vast majority
of bacteria are not harmful to humans,
there may be bacteria in the culture that
could cause infection on contact. Be sure
to wash with soap and water if the culture
gets on your skin. Rinse out your eye with
lots of clean water if any of the culture
liquid contacts it. If you get any of the
water in a cut be sure to wash it out and
sterilize it with hydrogen peroxide or
iodine. |
