The Effect of Temperature on a Goldfish's Breathing Rate

The Effect of Temperature on the Breathing Rate of Goldfish

Rebecca Rose

Partners: Jennifer Ellis, Hunter Cook, Cole Hodges

Tuesday 9am Lab

February 20th, 2018

Abstract:  The purpose of this investigation was to determine how a change in temperature affects the rate at which a Goldfish breathes.  The goldfish was placed into a glass of water which was inside a bowl which my partners and I added ice to in order to lower the temperature of the water.  We then measured the amount of breaths taken by the goldfish in periods of fifteen seconds, which we later multiplied by four to determine the breathing rate per minute.  The results from this experiment concluded that the lower the temperature of the water, the slower the rate of the goldfish’s respiration, which supports our hypothesis.

Introduction:

        There are two different responses that organisms experience in response to environmental changes.  An endothermic organism, such as a human, is able to maintain a constant body temperature due to a built-in mechanism in its body, whereas an ectotherm must rely on its surrounding environment to maintain body temperature (Pearson, pg. 51).  Fish are ectotherms, therefore the temperature of the water determines their body temperature; if water temperature decreases, then a fish’s body temperature decreases as well, and vice versa.

        Fish breathe via their gills which are located in the gill cavity outside their throats (Pearson, pg. 51).  Fish gills are filled with blood vessels and are underneath the operculum which protects them.  This operculum is helpful in “pumping water continuously and smoothly through the mouth, into the pharynx, across the gills, and out an opening beneath the raised opercular flap” (Pearson, pg. 51).  This process, known as gas exchange, is how fish get rid of carbon dioxide and obtain oxygen.  It enables the organism to receive energy from the food molecules from the digestive system (Campbell, pg. 458).  The blood then transports oxygen to the part of the body where it breaks down glucose and fatty acids to make ATP (Pearson, pg. 52).  

        A fish’s respiration varies in response to the need of their cells for ATP, which is formed from stages of cellular respiration that requires oxygen.  Therefore, the demand of the cells for ATP increases as the chemical activity increases (Pearson, pg. 52).  This demand for ATP also increases the need of cells for the oxygen gained by breathing, which can explain why a fish’s body temperature would affect its breathing rate.  In this experiment, my partners and I hypothesized that the fish’s breathing rate would slow as the water temperature decreased; compared to the null hypothesis which states that the fish’s breathing rate would remain the same as the temperature decreased.  

Method:

        This experiment was conducted by gathering data from a control group and an experimental group.  The control group, which is the group that is left unchanged and used as a comparison to the altered group, was a fish in water with a constant temperature.  The experimental group, which is altered to test the hypothesis, was a fish in water that was constantly decreasing, starting from 20˚ Celsius and finishing at 10˚ Celsius.  The differences in these groups should be the result from the effects of the variable that was altered, which is known as the independent variable.  Both goldfish were observed and a group member timed them for 15 seconds while a different group member counted the number of times the fish’s opercular flap opens.  The control group’s goldfish had a steady temperature, while the experimental group decreased the water temperature by 5 degrees Celsius and recorded the number of breaths per 15 seconds three times.  The number of breaths taken per minute is the dependent variable in this experiment.