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

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 CO 2 production Used Sable software to convert CO 2 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) varianceave min T (°C) ave max T (°C) individual min (°C) individual max (°C) 24 hr constant light hr constant light hr 14L:10D

Results: Metabolic Rate

Results: Circadian Rhythms

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 Pikovsky