Advice for sampling

[mazo4033]

Hi all,

I've run into a sort of problem with sampling water. I take water samples and they yield few microorganisms.

I aim to sample from water that shows signs of life (algae growing on the surface, plants around the edge of a pond, plants in the water, etc). I also sample from water that looks kind of murky. When I take samples, I make sure to take the water along with some sediment. I made the assumption that obviously these sorts of procedures should yield microorganisms.

However, I essentially have only experienced one successful sampling location, which is a river. I've sampled from other places (pond-like waters), and when I put the water (along with some sediment) on slides, there are no large microorganisms like ciliates. There are just bacteria or the occasional very small flagellate. I don't think this is a seasonal issue as this has been the case in the summer and the winter. I look at the samples the day of sampling (and some time after as well), so it's not like the organisms have died off or something.

I don't understand what I am doing wrong - is my sampling technique incorrect? Should I take deeper layers of sediment? Any advice would be helpful - I feel like people just casually take samples of water and find many organisms and for some reason the majority of my sampling has not yielded much.

Thanks in advance!

[Greg Howald]

Make sure to take some of the plant life with your sample. Get a good sample. In a one quart wide mouth jar you need about 1 1/2 inches of bottom mud, plant life, and water sample from the surface with floating plant life. If you see few microbes, feed the container with a few grains of cooked rice and a few drops of milk.
Seal the jar so that it is air tight. Set it in the window sill for a week or two and try again. Microbes will wax and wane over time from great abundance to few and rebirth seems to occur. I keep the water at room temperature. If you decide to incubate don't exceed 85 degrees F.
It can be a waiting game. I have one jar over a year old.
Good luck. Have fun. Greg

[BramHuntingNematodes]

Maybe it's just where I live but I can grab a few drops with an eye-dropper from any outdoor standing water and find it swimming with life. You might try looking at some water from a potted plant, a birdbath, inside a tree stump, on top of a leaf, in a muddle puddle. Finding some specific organism, a real microbe hunt, that's a bit trickier.

[mazo4033]

Thank you both for the advice. Culturing/feeding the container is a good idea, and I will make sure to keep more plants in the sample!

[crb5]

You could try collecting with a plankton net which concentrates the sample a few hundred to a few thousand times, depending on the depth of the water column you sample.

[MicroBob]

Plancton concentration in free water is very low, so you will only get a rich sample with a net of filter. You can make a plancton net or filter yourself, I could point you in the right direction.
A lot of life is usually found atattched to plants and wooden surfaces.
I'm member of an old microscopy group and our oldtimers tell that plancton concentration and diversity have dropped a lot in the past 60 years. Some guys are researching the desmids in moors around here. At first they were unhappy to find a much reduced variety, but when sampling more moors in more placed they found a wide variety. So it is likely that you will be able to improve your results over time. Plancton life also has it's yearly cyclus and changes a lot at each single sampling position.

[mazo4033]

Thank you crb5 and MicroBob. The plankton net is a good idea.