Hay Infusion
The city of Sudbury is known for its many
lakes and its great summers. At some point this
past summer you may have gone swimming/skiing etc… in one of the
local bodies of water. Wouldn’t it be great to know what you were
swimming with?
In this activity you will examine a hay infusion. A hay infusion is a
culture made from water collected from a pond, lake, stream, or puddle. If you
were to examine pond water without culturing it, you’d have a difficult time
spotting microbes (microscopic organisms). The hay infusion will be prepared by
adding water to dried grass/hay. The microscopic organisms that are present on
the grass multiply in number using the nutrients from the decaying grass for their
growth. Once the population of these organisms is sufficient, their predators
which were present in the culture (pond water) in small numbers are able to
reproduce. The populations of the various types of organisms will change over
time. It will be necessary to examine the hay infusion in many lab periods. These
times will be designated by the teacher.
Factors that may affect your hay infusion:
1. Amount of light
2. Evaporation
3. Pesticide use on the grass
4. Amount of grass
5. Amount of oxygen
Instructions/Notes:
1. Put the pond water into a large beaker/mayonnaise jar/jam jar and add pieces
of cut up hay or grass. Cover the lid loosely.
2. In a journal (or page), make note of the following:
-temperature of the culture
-life present
-water level
-smell of the hay infusion
-colour/turbidity of the hay infusion
- date/time
3. Keep track of your hay infusion. If you do not know what organism you are
looking at, look it up! A guide to pond life will be provided but may not have all
organisms present.
4. A lab period on how to prepare wet mounts will be done.
5. It is necessary to draw the organisms you see.
Discussion
At the end of the pond life study, answer the following questions:
1. Where did the organisms come from that you saw during the observation
periods? Give two reasons why some organisms may not have been observed
during the first week, but appeared in later weeks.
2. What happened to the diversity of the organisms in the infusion over the
course of the observation period?
3. As the number of consumers increases, it is quite common to note a decrease in
the turbidity of the infusion. Why?
Watch out for the smell!!!