How to get an algal suspension

[tokitori]

Hi, for my science fair project, due Jan 22, I am trying to see whether increased temperatures increase algae growth.

The part I'm having trouble with, is, the stuff I found on how to do the experiment said that I should put aged water (tap water that stands for at least 3 days) into a flask, and add an algal suspension into each flask.

I would like to go to Lake Mead or the Desert Wetlands Park here where I live to get algae, but will that work? Because my mom thinks it might not, so we also ordered live algae, chlorella, (grown on Alga-Gro Freshwater Medium) from Carolina Biological Supply Company. (The specifications say light level, high, temperature, 22 degrees C. and it says each culture contains enough material for a class of 30 students and we bought 3 cultures so I know we have way too much.)

I am then going to keep an equal light source (flourescent) and have one flask room temperature, one warm, and one cool and then I'm going to record growth each day for a week by taking 1 ml of the culture from each flask and count the number of cells in a 10x field (actually, get an average for each so 3 samples each) and also record the temperature of the water each day.

So what I need to know is, can I just get algae from one of our local lakes and add that to water and test it on that, or should I use the chlorella we bought and how do I do that? Do I just take some of the stuff we bought and mix it with the aged water and then take each sample each day from that?

I only bought 3 flasks or else I would just try to use the regular algae from the lake and also the stuff we bought but also it might take a long time to count all the algae so I need to narrow it down, I think.

Thank you!
Andie

[barretttomlinson]

Hi,

You seem to have thought out your experimental design carefully. It is generally extremely easy to get algae to grow. If they have water, sunlight, a reasonable temperature and air they usuallydo really well. It seems to me you have absolutely nothing to lose by trying to grow algae from the lake. You don’t need a special flask - an empty food jar will work just fine. When I was your age I put three shampoo bottles filled with water and stoppered with cotton in our living room window(I did not even seed the bottles with algae), and within two weeks had a really thick algae soup.

You could use your chorella sample with the flasks you bought to do a safe backup. You could also try a parallel comparison experiment with the lake samples in discarded jars, just to see what will happen. There is no law that says you have to count the lake algae cells unless you want to. So if you try it out and the lake algae doesn’t grow, you have lost nothing - the chorella experiment will give you the data you need. If the lake algae does grow (and I am quite sure it will) you can direct your experiment whichever way you choose. Follow your instincts and curiosity! Many of the best experiments are done because someone gets slightly curious about something, and just does an experiment to see what will happen.

The important thing is to try to satisfy your curiosity, and above all, have fun!!!!

Go for it!!

Best regards,

Barrett Tomlinson

http://www.wikihow.com/Grow-Algae

[adance]

Hi Andie

I agree with Barrett--why not try both?

Then you can compare your "wild-caught" algae with "tame, lab-grown" stock. It would be interesting if they responded to growth differently! For example, perhaps the lab stock are better at growing in a bottle, since that's what they've been selected to do.

Scientists often use a standard lab stock for control purposes. That way they know exactly what they have, and they know it is the same as what other scientists are working with, so they can compare their experiments more easily. But, the result is that over time in the lab, the standard stock evolves to be different from what the natural culture is.

Sounds like you have a good plan. Good luck!

amber

[tokitori]

Thank you Barrett & AMber, I am going to do both, and went and got Lake water today.
Also, I made a mistake in my first post and said I had to count the algae in a 10x field but I meant 100x field.
But now, I am supposed to add my algae to water. But I don't know how much water. I don't want to dilute it too much, because I worry that it might kill my algae or make them so diluted I won't get enough to count.
The chlorella that I bought came in skinny test tubes, about thickness of a hi-liter marker and about the same height.
I'm supposed to add this to a "supply of" aged water, but it doesn't say how much.
I'm supposed to take a 3 samples from each flask (cool, room temp and warm) and record the average number of algae in the 100x field.
Each sample is 1 ml, so 3ml for 7 days. So 21 ml per flask. If I add my highlighter sized test tube to 21 ml of water, do you think that would be too diluted?
Thank you,
Andie

[tokitori]

And one more question.
I live on a ranch and we have well water. My mom says our well water does not have chlorine in it. But it is very hard water.
But I could also use distilled water.
Would distilled water work better?

[tokitori]

Now I have to correct my previous question.
I was thinking that I would throw out each sample after I counted it, but then the water would run out and the warm water that I will have sitting above the heating pad will get too hot since there will be less water in the flask.
So now I'm thinking I won't be throwing out the samples, I'll be putting them back in the flask, won't I?
So then should I just, like, add about twice as much water as the test tube, since I'll probably spill a little?
I'm panicking a little but also really want to get started and everytime I think I'm getting started I think of another question!
Sincerely,
Andie

[adance]

It's good that you're trying to think everything through before you get started!

I would recommend against putting the water samples back after you count the algae. While you're counting, the samples could get contaminated with different kinds of algae, or otherwise get dirty.

You shouldn't need too much volume to count cells on a microscope. But yes, you should have enough water in the bottles so there will still be plenty after you take out your samples to count.

good luck

amber

[barretttomlinson]

Hi,

From what you said in your first post (1 culture tube is enough for 30 students) I would conclude that you should need only about 1/30 th of a tube ( about 1 ml?) to seed your water. Under favorable conditions algae grows VERY fast in an exponential pattern. I don’t think they can be killed by diluting them. I suspect your problem will be getting them dilute enough to count, not getting them concentrated enough to count. I think you want your day 0 concentration to be low enough that you can still count if the number of cells per sample volume goes up a thousand fold during your experiment.

If you want a model experiment to follow, here is a slightly more advanced experiment writeup:
http://www.unc.edu/courses/2008fall/env ... %20lab.pdf

You may also want to read this paper carefully, as it describes how to grow starting cultures of algae in a near ideal medium(and how to make the medium):

http://www.epa.gov/bioindicators/pdf/mpcb91_charles.pdf

As to the suitable water to use, I would vote for well water though distilled water should also work. If your water is hard because of dissolved carbonates the algae will likely view the carbonate ions as extra food. However some chemistry labs in which I have worked have had to contaminate their distilled water with copper sulphate to avoid having algae grow in it Algae are very, very resourceful and hard to kill, though copper ions are pretty effective at detering their growth.

Good luck, and don’t worry too much that a slight error will ruin your experiment! It probably won’t, and even if it does you might learn something more important than you expected to had the experiment worked the way you expected.

Barrett Tomlinson