The effects of temperature on metabolic rate as seen in the Tropical Zebra Fish (Danio rario)

Zebra fish (Danio rerio) subjected in 30oC water samples had larger mass specific oxygen consumption rate.  They had 3.5X more mass specific oxygen consumption rate than zebra fishs treated in 20oC water.  

    Oxygen demand by all animals is seen to be driven primarily by their metabolic needs.  Fish are poikilothermic animals and in being so are thermal conformers which makes there metabolic rate dependent on the temperature of the environment they are in (Glencross, 2006). The lab experiment performed uses the Winkler method to study the effects on Zebra fish (Danio rario).  This study was done in two temperatures of water.  One set of fish were acclimated to 20 degree Centigrade water and the other to 30 degree Centigrade  water.  Metabolic rates were measured during this process and it was noted that Zebra fish exposed to cold water (20 degree) had lower metabolic rates than those that were exposed to warm water (30 degree).  In fact, their oxygen consumption rate was 3.5 times as high as the alternate fish.  This study was designed to test the hypothesis that water temperature affected metabolic rate in a poikilothermic animal.  This paper will discuss the results of this study in relation to other studies done.

    It is known that Zebra fish like many invertebrates are thermal conformers .  In these animals the outside temperature affects metabolism and therefore their need for oxygen consumption.  It also means that there is only so much this animal can take related to temperature. On the other hand, we as humans have an internal body temperature that is not affected by outside temperature.  In other words humans and mammals can live almost anywhere based on the fact that they can regulate their own temperature but thermal conformers are restricted by the temperature of their habitat (Glencross, 2006). However, the study done by Cortmelia, Beitinger,  Kennedy tell us that Zebra fish can live in a different environment, it is just somewhat limited.  In a study done by Cortemeglia, Beitinger,  Kennedy, 2006) in which Zebra fish were placed in the wild under different temperatures.

    Cortemeglia took zebra danios from two pet stores  in Northern Texas.  They were placed in fibreglass microcosms outside.  The fish were allowed one hour to adjust to water temperatures before the testing began.  In this case the temperatures were at four levels instead of the two used in our experiment. 13 fish out of 68 survived at temperatures of 7.5 degrees Centigrade and none survived at a 4 day exposure of a cold snap that dropped the temperature to 4 degrees Centigrade.  It is noted that the lowest surviving temperature was 5 degrees centigrade. Testing throughout the Winter, however, noted the same type of results that were found in this lab study including that the metabolic rate was much lower as was oxygen consumption at lower temperatures, however, survivability can only be reduced to 5 degrees and not lower.(Cortemeglia, 2006).

    Cortemeglia (2006), showed throughout their study that metabolic rates and oxygen consumption increased as the temperature increased and was much lower in the fish that were in the coldest microcosms. This is further supported by a study done by Kranenberg, Boogart, Jos in which they tested the oxygen profile of Zebra fish in an experiment which concluded that tropical fish consume at least 6 times more than non-tropical fish. It was noted throughout their study that oxygen rates were lower in those fish that lived in colder water and therefore they did not need to support a metabolic rate so high.  This reduces the amount of food they must eat to maintain. This is part of the reason why the fish died in the Texas study.

    In conclusion, the lab study conducted is well supported by previous research.  The results obtained here run very close to the results noted in the other studies though some of the technique used here may not have been as good.  An example, in the Texas study, the fish were acclimatized first and they were never touched by humans which is not true in our case. The temperatures might have been colder as some of the studies being done now show that Zebra fish in particular are able to withstand lower temperatures and this might affect our results.


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