Daphnia Lab Report

The effects toxins such as caffeine, nicotine, epinephrine, ethanol and salt have on the Daphnia magna’s heart rate
Results
The effect the various drugs caffeine, nicotine and epinephrine had on the Daphnia magna is displayed in Figure 1. After three sample trials were taken there was an average of 180 beats/min-1 ± 6.928 taken under normal conditions. The addition of caffeine caused an increase in the average heartbeat to change to 192 beats/min-1 ± 9.165 in the Daphnia magna tested. When testing the effect of nicotine on the Daphnia magna the average heart beat was 168 beats/min-1 ± 3.4641 taken under normal conditions. With the addition of nicotine, this caused a decrease in the Daphnia’s heart beat with an average of 146 beats/min-1
When looking at the effects caffeine and epinephrine had on the heart rate of the Daphnia magna, it showed that they are stimulants by the increase in the Daphnia’s heart rate in comparison to the heart rate of the control group. This reflects accurate results reproduced by another experiment performed by Campbell et al (2004). When looking at the effects nicotine and ethanol had on the heart rate of the Daphnia magna, it showed that they were depressants by the decrease in the Daphnia’s heart rate in comparison to the heart rate of the control group. The results of Ceballos et.al (2010) supported the results obtained in this experimental. Ceballos et.al (2010) experiment analyzed further and noticed that the nicotine had different effects on the Daphnia’s heart rate based on two factors, the amount of time that was given for the Daphnia to absorb the nicotine and the concentration of nicotine given to the
The results did not support this hypothesis. It has been established that heart rate in Daphnia magna increases when there is a progressive lack of oxygen present. (Baumer et.al 2002). When the salinity of water increases there are increases in Na+ ions as well as Cl- ions. This increase in ion concentration causes a change in osmotic alternation and a competition between all the ions. (de la Paz Gomez-Diaz and Martinez-Jeronimo 2008). Although increase in salinity has been known to be detrimental to the health of the Daphnia magna, if high enough can result in mortality, Daphnia magna can adapt to low levels of salt (Baillieul et.al 1996). Since the Daphnia magna are freshwater crustaceans the lower the salt concentration there is the closer the heart rate should be to the resting heart rate of the Daphnia. Possible errors that could have gone wrong are the duration given to allow for the absorption of the different concentration of salt solutions due to the limited time during the lab period and the distinguishing of the separate heart beats and the inaccuracy of a constant time being off by points of a