Four randomly selected Daphnia magna, for each trial, were removed from the provided colony for the bioactive compounds to be tested, and were transferred with a plastic wide-mouth pipette with approximately 10 mL of pond water to protect and ensure survival of the Daphnia. In order to acclimatize the Daphnia to laboratory conditions, they were then placed onto a petri dish on the Daphnia cooling chamber. The cooling chamber was located on the stereomicroscope platform and brought down the heart rate of the Daphnia to a range that was countable by the observer, since Daphnia heart rate at room temperature is too rapid. On the cooling chamber there were two petri dishes: one for the Daphnia that were going to be tested, and one with the Daphnia being tested on, to ensure constant consistent temperatures for each trial. To maintain a temperature conducive to the heart …show more content…
Research Protocol – Monitoring of the Daphnia magna heart rate The experiments focused on the four treatments of nicotine, caffeine, ethanol, and double distilled water (placebo). 180 μL of each bioactive solution (nicotine was covered with foil, due to light sensitivity) and 120 μL of double distilled water were placed into labeled eppendorf tubes to dismiss cross-contamination, and were placed on ice to match the environment of the Daphnia to reduce any added stress on the Daphnia. One Daphnia was placed on the testing petri dish, and then all the excess pond water was removed with a transfer pipette. Immediately 10 μL of double distilled water was added with a micropipette; this way our concentration of the treatment was the intended concentration.