Search This Blog

Monday, 21 November 2011

Culturing algae, green slime and animalculi

videoThis 6-meg video was taken through my microscope.  It's there mainly to show you how some of the things you see actually look under the microscope. The cup-on-a-stalk low on the screen is a rotifer, the long whizzing thing is a Paramecium, and the little round things are little round things.

They all grew in one of my algal culture systems, so there is every chance that you could see the same things with your cultures as well.

In this entry, I will show and tell you how to set up cultures, and explain some of the tricks I use to get good results. There is no best method, but there are lots of good methods.

My suggestion is that you take my ideas and work them up into what you want.

First, here is a method that I used to use, some 40 tears ago. I had a series of large glass bottles, all with air coming from a small aquarium pump. At the end, the air bubbles through a tray.

I would put each inlet tube (the bubbling ones) just below the water surface, to avoid too much strain on your air pump. You need clear bottles so light can get in to make the algae grow. Looking through towards sunlight on a sunny day, you may be able to see either a Paramecium, or an Amoeba in your cultures, so look these up on the web.  You may also see some very tiny crustaceans: look for tiny moving dots.

Because I often wanted to open one of the bottles, I used plastic tubing for the connections, even back then, because glass tubing would have been too dangerous. In the end, though, I decided that this method was unnecessary.

Here is the kit that I had set up, just outside my study window, in full sunlight. The old film canisters were used to collect water from puddles and streams, so there were always new organisms likely to be getting into the system. At this time, I needed mosquito wrigglers, and I used the flat dish to collect some.

The main extra was that I added some fertiliser to the water samples.  Not a lot, just enough to make sure the plant life had something to work with.  Note that some of the containers are back in the shade: the dish, in particular, got up to 60°C on some summer days, and that was another variable.

A hay infusion
The traditional method, though, is to prepare a hay infusion.  This is the traditional name given to this sort of thing, dating back to the days of people's horsepower having four legs. You don't really need hay: any plant matter that has been lying around will do.

You will need an old saucepan, a bucket, a few PET bottles to store cultures in.  PET bottles are those clear plastic bottles that soft drinks come in.  Use the 1.25 litre size, but never fill past the point where the sides slope in near the top, because you want a large water surface for gas exchange.

(One handy trick: if there are small crustaceans in a bottle, if you fill the bottle almost to the top, oxygen levels will drop, and they will all cluster in the top 5 mm (where there is more oxygen), where you can catch them with an eye dropper.)

Use the saucepan to boil some grass or chopped-up leaves in water.  After it has cooled, let the water stand in a bucket for a day or two. Use the water to cover some cut grass or leaves, and put the container in a warm place, out of direct sunlight. You can speed things up if you add a few small slops of water from a pond or a slow stream, or some of the cloudy water from the bottom of a vase of dead flowers.

I am usually in a hurry when I need algae, so I have a few extra PET bottles, half full of water and assorted gunk samples that serve as sources. I can use these to get a new culture started, or I can draw samples.

A few small water samples from random pools and ponds can help boost the variety in your infusion containers. One of the best ways to collect water samples is to get a used washing-up liquid container, the sort that has a pop-up/pop-down lid. Wash this out thoroughly and take it with you when you go walking.

When you find some nice water, pop the lid open, squeeze some air from the bottle, turn it upside down, push the top under water and unsqueeze to get a sample. You can increase your animal catch by taking water from close to plants, rocks or the bottom. Always take a plastic bag to wrap the wet bottle in after you have taken a sample. I now always wash my hands after taking samples like this, using bottled 'hand-wash', and I recommend that you do the same.

After that, you will need a bit of patience, because the best results and the biggest surprises come from cultures that have been going for a while.  In the next entry, I will talk about some of the stuff you can see.

Here's one example, at a magnification of x400. It's what we call a filamentous alga, but which one it is, I'm sure I don't know.  Like you, I'm just a hobbyist, dabbling where I feel like dabbling.

No comments:

Post a Comment