Preferred Temperature, Metabolic Rate, and Circadian Rhythms

of Snapping Turtles (Chelydra serpentina)

Amy Pikovsky2004-05

Introduction

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

Background

• Snapping turtles are ectotherms• Ectotherms’ body temperatures are the same

as environmental temperatures

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.

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

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.

Materials

the temperature gradient

picture taken by author

• 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

Methods: Preferred Temperature

Methods: Metabolic Rate

• Set lights in the incubator to 14L:10D cycle

• Placed turtles in separate containers in incubator

• Measured CO2 production • Used Sable software to convert CO2

data into metabolic rate data

Methods: Circadian Rhythms

• Set lights in the gradient room to 14L:10D cycle

• Graphed temperature data• Looked for patterns

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 14L:10D

18.4 10.8 13.9 25.7 9.7 34.1

5 10 15 20 25 300.00.10.20.30.40.50.6

Carbon dioxide produced (ml per hour)

B

temperature (degrees Celsius)

Mean resting metabolic rates of nine turtles at a variety of temperatures between 5.0 °C and 30.0 °C.

Results: Metabolic Rate

81012141618202224262830323436

Temperature ( degrees C)

Turtle 1 Turtle 2 Turtle 3

1:0013:00 13:00 1:00 13:00

Figure 1A: 48 Hours Turtles 1-3

Time

lights onlights offlights onlights on lights off

Selected temperatures of turtles 1, 2, and 3 during the first trial, 48 hour preferred temperature experiment in 14L:10D.

Results: Circadian Rhythms

81012141618202224262830323436

Temperature (degrees C)

Time

Turtle4 Turtle5 Turtle6

11:00 23:00 11:00 23:00 11:00

Figure 1B: 48 Hours Turtles 4-6 lights onlights offlights onlights on lights off

Selected temperatures of turtles 4, 5, and 6 during the second trial, 48 hour preferred temperature experiment in 14L:10D.

81012141618202224262830323436

Temperature (degrees C)

Time

Turtle 7 Turtle 8 Turtle 9

12:30 00:30 12:30 00:30 12:30

Figure 1C: 48 Hours Turtles 7-9lights onlights offlights onlights on lights off

Selected temperatures of turtles 7, 8, and 9 during the third trial, 48 hour preferred temperature experiment in 14L:10D.

101520253035

lights onlights offlights on

Temperature

Time13:00 1:00 13:00 1:00 13:00

lights on lights off

Mean of Trials 1A-1C

Mean selected temperatures of all nine turtles. Error bars show standard error.

Conclusions: Preferred Temperature

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

Conclusions: Metabolic Rate

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

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

Future Studies

• Research continues at the University of St. Thomas on:

Future Studies

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

Future Studies

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

Significance

• Body temperature is very important to ectotherms

• Snapping turtles are common• Changes in weather and temperature

Acknowledgements

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

Preferred Temperature, Metabolic Rate, and Circadian Rhythms

of Snapping Turtles (Chelydra serpentina)

Amy Pikovsky2004-05