Preferred Temperature, Metabolic Rate, and Circadian Rhythms of Snapping Turtles (Chelydra serpentina)

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Preferred Temperature, Metabolic Rate, and
Circadian Rhythms of Snapping Turtles (Chelydra
serpentina)

• Amy Pikovsky
• 2004-05

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Introduction

• My goals were to find
• -Preferred temperature
• -Metabolic rate
• -Circadian rhythms
• -Correlations between the three variables

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Background

• Snapping turtles are ectotherms
• Ectotherms body temperatures are the same as
  environmental temperatures

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Importance

• Information about the effect of temperature on
  snapping turtles can be applied to all
  ectotherms.
• Snapping turtles are common, studies can then be
  applied to less common species
• Little research has been done about the
  interrelatedness of preferred temperature,
  metabolic rate, and circadian rhythms.

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Previous Studies

• L.U. Williamson, et al. researched body
  temperature affects on metabolic rate in 1989
• K.B. and J.M. Storey researched the affect of
  very low temperatures on the metabolic rates of
  ectotherms in 1984
• A. Cortes et al. studied metabolic rates in
  diurnal and nocturnal ectotherms in 1994

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Hypotheses

• Turtles will prefer higher temperatures with the
  lights on than with the lights off.
• Turtles metabolic rates will be higher at warm
  temperatures and lower at cold temperatures.
• Turtles metabolic rates will be higher with the
  lights on than with the lights off.

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Materials
the temperature gradient
picture taken by author
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Methods Preferred Temperature

• Initially, used T.V. and V.C.R. to find turtles
  positions
• Wrote LabView program to record positions in the
  gradient more easily
• Found corresponding temperatures
• Used two procedures
• 24 hour test in constant light
• 48 hour test in constant light

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Methods Metabolic Rate

• Set lights in the incubator to 14L10D cycle
• Placed turtles in separate containers in
  incubator
• Measured CO2 production
• Used Sable software to convert CO2 data into
  metabolic rate data

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Methods Circadian Rhythms

• Set lights in the gradient room to 14L10D cycle
• Graphed temperature data
• Looked for patterns

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Results Preferred Temperature

• Descriptive statistics

Mean (C) variance ave min T (C) ave max T (C) individual min (C) individual max (C)
24 hr constant light 18.4 14.8 13.6 27.3 9.2 32.2
48 hr constant light 21.2 23 13.2 31.3 10 34.3
48 hr 14L10D 18.4 10.8 13.9 25.7 9.7 34.1
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Results Metabolic Rate
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Results Circadian Rhythms
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Conclusions Preferred Temperature

• Preferred temperatures were moderate (around 20
  ºC) whether the lights were on or off

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Conclusions Metabolic Rate

• Metabolic rate and temperature were directly
  related higher temperatures cause higher
  metabolic rates

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Conclusions Circadian Rhythms

• Some circadian patterns were evident turtles
  moved more when the lights were on but the
  presence or absence of light did not affect
  temperature choice

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Future Studies

• Research continues at the University of St.
  Thomas on

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Future Studies

• Research continues at the University of St.
  Thomas on
• Circadian rhythms of ectotherms

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Future Studies

• Research continues at the University of St.
  Thomas on
• Circadian rhythms of ectotherms
• Preferred temperature in the field

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Significance

• Body temperature is very important to ectotherms
• Snapping turtles are common
• Changes in weather and temperature

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Acknowledgements

• Dr. Steyermark
• Dr. Nelson
• Anthony Giang
• Students from Dr. Steyermarks laboratory
• Ms. Fruen
• The research class

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Preferred Temperature, Metabolic Rate, and
Circadian Rhythms of Snapping Turtles (Chelydra
serpentina)

• Amy Pikovsky
• 2004-05