The effect of Temperature on the Respiration Rates of Fish

Bryan France, Sarah Flannery, Lara Chamberlain

CU Boulder, Fall 2002

We tested the respiration rates of fish at two different temperatures,

76 degrees Fahrenheit and 71 degrees Fahrenheit.  From a prior experiment performed in class we proved that the respiration rate of crickets changes when the surrounding environment gets warmer or colder.  Crickets and fish are both exothermic and exotherms’ and their metabolic and respiration rates differ with the temperature of the surrounding environment.  We hypothesized that fish have higher respiration rates in warmer water because metabolic rates are faster in a warmer climate for exotherms.

To test this hypothesis, we observed fish in two different tanks with different temperatures of water.  One tank was set at 76 degrees Fahrenheit and the other at 71 degrees Fahrenheit.  We measured the respiration rates of three different size categories of fish, large, medium, and small.  We determined that the smaller fish are younger then the larger fish.  To measure the respiration rates of fish, we counted the number of times the fishes’ gills opened in one minute.  Each trial was run three times for each fish in both tanks of water to total nine trials at each water temperature.  We predicted that both respiration and metabolic rates of fish would be greater in the 76 degree Fahrenheit tank than in the 71 degree Fahrenheit tank.

Our results showed that the respiration rate of fish was greater in the 76 degree Fahrenheit tank (mean=203 breaths per minute) than in the 71 degree Fahrenheit tank (mean=79 breaths per minute) (p=0.04).  Another trend we observed, although not significant, was that smaller fish have a higher respiration rate than larger fish in both temperatures (p=0.19).

Our results supported our predictions based on our hypothesis. 

Potential problems with our experiment are that there may have been a discrepancy between the number of breaths counted and the actual number of breaths that the fish took in a minute.  Another potential problem could have been that the two groups of fish were not exactly the same species, though both groups of fish were form the order, cyprinodontiformes.  This was the closest relationship that we could fins within our given resources.  Results of Hangge et al. 2001 on the CABLE web site demonstrated similar results to our experiment.  The temperature of the surrounding environment directly affected the respiration rates of darkling beetles.  Lavin and Williams 2001 on the

CABLE web site also found similar results involving the respiration rates of mealworms.  If we were to elaborate on this experiment, we would like to isolate the dissolved oxygen content and test solely that variable.  We could do this by isolating fish in two tanks with the same water temperature and allow one tank to have flowing water while keeping the other stagnant.  Since flowing water is more likely to have higher dissolved oxygen content than stagnant water, we can speculate that fish in a tank with the flowing water will have higher respiration rates.