Collecting amoebae

 

I collect my material from all kind of waters, but mainly from fresh water marshes and ditches in the central area of the Netherlands. This area has very different types of water, ranging from oligotrophic to eutrophic, from peat bogs to lakes, from streams to stagnant water. I have always some small glasses in my pocket, in case there is an opportunity to sample something. Usually I collect amoebae from the muddy surface of ponds and ditches, but when I see pieces of floating debris, I will always take something with me. These pieces can be very interesting.
My favorite tool for deeper water to collect amoebae is a jar fetched to a long thin rope. I throw the jar into the water, wait till it has reached the bottom and then pull a little to move the jar and to whirl some sediment into the jar. Then I pull the jar out of the water and transfer the sample into a clean glass. I label the glass with the name of the sample location and the date. I also make a photograph of every sample on location. My camera places the GPS-coordinates and time in the photo.
I use the jar-on-a-string method because the bottom of most ponds and lakes here are covered with a thick layer of decomposing organic material. Therefore I have usually no problems with sand grains in my samples, which can be extremely annoying in a wet mount. Sand can create several problems with microscope slides. When I collect material from water with a sandy bottom, usually covered with a thin layer of decomposing organic material, I try to avoid taking up the sand. 

 

Siemensma
Siemensma
Very handy for shallow water, an extendable stick with jar

At home I scan the samples within 24 hours, to see if they are worth further studying. Promising samples are left at room temperature, avoiding exposure to direct sun­light. Usually I leave about three centimeters of water above the sediment. Depending upon the nutrients and associated microbial succession, samples can stand for two days or for months.

In springtime, due to algae activity, pieces of bottom material gets floating. This material can be very rich in all kinds of amoebae, e.g. large Chaos amoebae. I get this material with a jar fetched to a long stick.

Waterplants and wet mosses are squeezed by hand, letting the water pour into a glass. Afterwards I filter these samples to remove larger particles as moss leaves. Dry mosses are collected in a plastic bag. At home, I put them in a large dish and add rain water. Then I stir and squeeze, remove the plants, let it settle and collect the residue in a smaller glass.

I use an inverted microscope for searching and isolating large shelled amoebae which may crash easily under a cover slip in a normal wet mount. After isolating the shell, I cover it with a slip, supported by some pieces of a broken cover slip. I also use an inverted microscope to isolate amoebae for staining, mounting and culturing.