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The Mean Oxygen Consumption Rate

The mean oxygen consumption rate levels were collected for 83 wild-caught crayfish, Orconectes propinquus, that were acclimated to either high (20 to 25˚C) or low (3 to 5˚C) temperatures. The crayfish acclimated to higher temperatures, had a mean oxygen consumption rate of 4.74 ± 0.303 μg·min-1·g-1 for the 0 to 30 minutes time interval, a mean oxygen consumption of 4.29 ± 0.365 μg·min-1·g-1 for the 30 to 60 minute time interval and the mean oxygen consumption rate overall from 0 to 60 minutes was 4.51 ± 0.266 μg·min-1·g-1. The average temperature was 20.3 ± 0.103˚C and the average mass of the crayfish was 8.67 ± 0.552g. The crayfish acclimated to colder temperatures, had a mean oxygen consumption rate of 4.28 ± 0.353 μg·min-1·g-1 for the 0 to 30 minute time interval, a mean oxygen consumption rate 3.69 ± 0.297 μg·min-1·g-1 for the 30 to 60 minutes time interval and the mean oxygen consumption rate overall of 3.99 ± 0.281 μg·min-1·g-1for the time interval of 0 to 60 minutes. The average temperature was 7.00 ± 0.205 ˚C and the average mass of the crayfish was 8.94 ± 0.447 g. A t-test was carried out and concluded that there was no significant difference in the mean oxygen consumption rate of the warm and cold acclimated crayfish, for the 0 to 60 minute time interval (t=1.37, df=81, P=0.179, Figure 1). Some values were removed from the data due to human and experimental errors. The Q10 value for the oxygen consumption rate was 1.10, this suggests the crayfish, acclimated to either high or low temperatures, exhibits no increase in the rate of oxygen consumption. Since no increase was exhibited, it suggests that the crayfish showed a compensation response to the rate of oxygen consumption in terms of temperature.

The crayfish, acclimated for two weeks in either the warmer or colder temperatures, had relatively similar results, regardless of the different acclimated temperatures (Figure 1). The similarity in the mean oxygen consumption rate suggests that the Orconectes propinquus supports the original hypothesis and shows metabolic compensations when acclimated at different temperature.

During the experiment, the acclimated crayfish were placed in respirometers, filled with the appropriate temperature water the crayfish was acclimated to. The respirometers were sealed with a plastic cover to eliminate the interaction between the water and the oxygen from the air. The oxygen consumption was measured in terms of body mass to reduce any variation that could have risen in the data. By measuring in terms of body mass, the results are ensured to be directly from the temperature. For both crayfish acclimated to colder and warmer temperatures, the rate of oxygen consumption decreased from the first time interval to the next. At the 30 to 60 minute interval, the amount of oxygen in the water has decreased because the crayfish has been consuming the oxygen for 30 minutes. Since the oxygen cannot be replenished, as the water is sealed from any interaction from the air where oxygen could be replenished, the amount of oxygen in the water continued to decrease as the crayfish continued to consume it.

The crayfish are ectotherms, this would mean that as the environmental temperatures changes, the body temperature of the crayfish would also change accordingly, which would cause the metabolic rates to increase or decrease with the temperature. This would suggest that although the acclimation of temperature does not have a significant effect on the Orconectes propinquus, ambient temperature does. For example, in an experiment, two different types of crayfish, Procambarus clarkii and Procambarus zonangulus, were placed in water each with a different acclimated temperature and were acutely exposed (Powell and Watts, 2006). The results from Powell and Watts experiment would imply that when a crayfish acclimated to warmer temperatures is exposed to colder temperatures, the metabolic rate would decrease and therefore the oxygen consumption rate would also decrease and vice versa if a crayfish acclimated to colder temperatures is exposed to warmer temperatures. If the crayfish are exposed for an extended amount of time, the crayfish eventually become acclimated to the new temperature and will compensate metabolically and return to its resting rate. The body mass of the crayfish could also affect the oxygen consumption rate. As the body mass increase, the metabolic rate of the crayfish would also increase, which would lead to the rate of oxygen consumption to increase accordingly.

At different temperatures of water, the oxygen availability in the water varies. The oxygen availability in colder temperatures is higher than in warmer temperatures because cold water can hold more oxygen than warmer waters (Bickler and Buck, 2007). This may have led to the evolution of metabolic compensation because it would have been more profitable for the crayfish to be able to survive in colder temperatures, to be able to consume more oxygen. This may have also led certain species of crayfish to become more adapted to less oxygen availability in warmer water and more oxygen availability in colder water to better survive in the environment (Wiens and Armitage, 1961). Hemocyanin binding affinities may also have aided the crayfish in adapting to the different temperature environment. Hemocyanin binding affinities may aid in reducing the effects that could hinder the survival of the crayfish (Powell and Watts, 2006). In crayfish with higher levels of hemocyanin binding affinities were able to obtain oxygen from the surrounding environment even if the oxygen levels were low (Powell and Watts, 2006).

Data collected for the different crayfish are variable. The variabilities were due to factors such as body mass and temperature, as well as human and experimental error. If the plastic cover, that is meant to seal the water from interacting with the oxygen in the air, was not placed perfectly on the surface of the water, it would allow for the water and oxygen to interact. This would result in an incorrect calculated oxygen consumption rate. Based on the data collected, the calculated Q10 value was near 1, this indicates that as temperatures increase, the crayfish has maintained a stable metabolic rate. The Q10 value suggests that the crayfish compensates to the temperature and is able to maintain a steady rate of oxygen consumption, which is shown

From the experiment, crayfish seem to show metabolic compensation when acclimated to either high or low temperatures. The cray fish can metabolically compensate to allow for the consumption of oxygen in environments that are of warmer or colder temperatures.

The crayfish, acclimated for two weeks in either the warmer or colder temperatures, had relatively similar results, regardless of the different acclimated temperatures (Figure 1). The similarity in the mean oxygen consumption rate suggests that the Orconectes propinquus supports the original hypothesis and shows metabolic compensations when acclimated at different temperature.

During the experiment, the acclimated crayfish were placed in respirometers, filled with the appropriate temperature water the crayfish was acclimated to. The respirometers were sealed with a plastic cover to eliminate the interaction between the water and the oxygen from the air. The oxygen consumption was measured in terms of body mass to reduce any variation that could have risen in the data. By measuring in terms of body mass, the results are ensured to be directly from the temperature. For both crayfish acclimated to colder and warmer temperatures, the rate of oxygen consumption decreased from the first time interval to the next. At the 30 to 60 minute interval, the amount of oxygen in the water has decreased because the crayfish has been consuming the oxygen for 30 minutes. Since the oxygen cannot be replenished, as the water is sealed from any interaction from the air where oxygen could be replenished, the amount of oxygen in the water continued to decrease as the crayfish continued to consume it.

The crayfish are ectotherms, this would mean that as the environmental temperatures changes, the body temperature of the crayfish would also change accordingly, which would cause the metabolic rates to increase or decrease with the temperature. This would suggest that although the acclimation of temperature does not have a significant effect on the Orconectes propinquus, ambient temperature does. For example, in an experiment, two different types of crayfish, Procambarus clarkii and Procambarus zonangulus, were placed in water each with a different acclimated temperature and were acutely exposed (Powell and Watts, 2006). The results from Powell and Watts experiment would imply that when a crayfish acclimated to warmer temperatures is exposed to colder temperatures, the metabolic rate would decrease and therefore the oxygen consumption rate would also decrease and vice versa if a crayfish acclimated to colder temperatures is exposed to warmer temperatures. If the crayfish are exposed for an extended amount of time, the crayfish eventually become acclimated to the new temperature and will compensate metabolically and return to its resting rate. The body mass of the crayfish could also affect the oxygen consumption rate. As the body mass increase, the metabolic rate of the crayfish would also increase, which would lead to the rate of oxygen consumption to increase accordingly.

At different temperatures of water, the oxygen availability in the water varies. The oxygen availability in colder temperatures is higher than in warmer temperatures because cold water can hold more oxygen than warmer waters (Bickler and Buck, 2007). This may have led to the evolution of metabolic compensation because it would have been more profitable for the crayfish to be able to survive in colder temperatures, to be able to consume more oxygen. This may have also led certain species of crayfish to become more adapted to less oxygen availability in warmer water and more oxygen availability in colder water to better survive in the environment (Wiens and Armitage, 1961). Hemocyanin binding affinities may also have aided the crayfish in adapting to the different temperature environment. Hemocyanin binding affinities may aid in reducing the effects that could hinder the survival of the crayfish (Powell and Watts, 2006). In crayfish with higher levels of hemocyanin binding affinities were able to obtain oxygen from the surrounding environment even if the oxygen levels were low (Powell and Watts, 2006).

Data collected for the different crayfish are variable. The variabilities were due to factors such as body mass and temperature, as well as human and experimental error. If the plastic cover, that is meant to seal the water from interacting with the oxygen in the air, was not placed perfectly on the surface of the water, it would allow for the water and oxygen to interact. This would result in an incorrect calculated oxygen consumption rate. Based on the data collected, the calculated Q10 value was near 1, this indicates that as temperatures increase, the crayfish has maintained a stable metabolic rate. The Q10 value suggests that the crayfish compensates to the temperature and is able to maintain a steady rate of oxygen consumption, which is shown

From the experiment, crayfish seem to show metabolic compensation when acclimated to either high or low temperatures. The cray fish can metabolically compensate to allow for the consumption of oxygen in environments that are of warmer or colder temperatures.