Testing the reactions of two aquatic organisms – vegetal and animal – in oxygen depleted environments.


Once our group was defined, our first thought was to get our box so we could see what our object was. Our group in my opinion had very good hardworking people in it but not enough variety; there were three biologists, one physicist and one biologist that was also a physicist. We realized very quickly that no matter what our theme was it was going to be hard to find four different biology experiments relating to that theme.

The object we received was an egg box with eleven eggs in it. We began brainstorming at once, everybody seemed to be giving an input but the problem remained; how were we to find a theme broad enough to create so many different experiments in the same subject yet not too broad as to lose the idea of a main theme.

We finally came up with our present theme; Air. The way we achieved this may seem a bit farfetched in relation to our object but we brainstormed progressively. “Eggs” led us to “Chicken” which in turn led to “Bird”, then “Flight” and finally; AIR.

This was the theme we decided upon as it was the one that gave us the most doors such as aerodynamics, respiration, atmosphere, etc.

As for my experiment I thought about the components present in air. The main one being oxygen I thought I could test the reactions of organisms under high and low levels of oxygen. I discussed this idea with a teacher, my main problem being of course the measuring of the reactions. After explaining my idea and my problem one teacher suggested counting a water flea’s heartbeats whilst another measuring the photosynthesis rate of an aquatic plant. The fact that these were completely different organisms and way of measuring compelled me. I was more than ever willing to carry out this idea but not only with one of these organisms but with both. This I was sure would guarantee many results, observations and interesting conclusions.
Aim: To determine the reactions of two aquatic organisms – Elodea and Daphnia – within low oxygen environments.

Hypothesis: It is possible to predict that the organisms will live more efficiently in environments of higher oxygen levels.

Variables:Aspects modified purposelyAspects maintained the same purposelyUncontrollable aspects

o The type of organism studied
o The time at which the water was left to boil
o The method of measuring the reactions of each organism
o The technique of depleting oxygen in the water – based on improving the first method. · The use of an animal organism and a vegetal organism – daphnia and elodea.

o The process of measuring the oxygen levels with an oxygen probe.
o The size of beakers for elodea
o The size of the beakers for daphnia
o The amount of water for elodea
o The amount of water for daphnia · The oxygen probe didn’t give the most reliable results due to a slight malfunction.

o Although a minimum of air was left in the beakers containing the specimen it is possible that the oxygen in those small amounts of air may have diffused into the water.
o The exact amount of elodea in the beakers
o The sex of the daphnia and their status quo (how healthy they were, whether they had eggs, whether they were ready for fertilization, all these factors may affect the heartbeats slightly)


· Elodea

· Daphnia

· Light bulb

· Clamp

· 6 big flasks + corks

· 6 small flasks + corks

· thermometer

· 2 boiling beakers

· tripod

· Bunsen burner

· Scalpel

· Box

· Microscope

· 6 slides

· Vaseline

· Pipette

· Oxygen probe

· Petri dish


Step 1 Begin the Elodea experiment by boiling water into the boiling beakers. Once the temperature has hit 98º begin counting the amount of time left to boil. Do this six times for the following amounts of time: 5 mins

10 mins

15 mins

20 mins

25 mins

30 mins

Step 2 After boiling for the amount of time required place as much water as possible in a flask as to minimize the air present. Label each flask and seal it immediately. Use Vaseline if necessary.

Step 3 Place the flasks in a box away from light in order for it to cool. You may place