Meeting Abstract

98.4  Thursday, Jan. 7  Temperature effects on metabolic enzyme activity in diamondback terrapins (Malaclemys terrapin) SOUTHWOOD, A.L.*; HARDEN, L.A.; University of North Carolina Wilmington; University of North Carolina Wilmington southwooda@uncw.edu

The diamondback terrapin (Malaclemys terrapin) spans a geographic range that stretches along the East and Gulf coasts of the United States from Massachusetts to Texas. It is the only estuarine species of turtle, and inhabits shallow, brackish waters of coastal marshes and creeks. In North Carolina, terrapins are most active from March through October and spend the winter months buried shallowly in the muddy substrate of the intertidal zone. Terrapins in this region experience air temperatures of 19.1 – 36.2&degC during the summer and -5.5 – 24.6&degC during the winter. Water temperatures vary from 24.6 – 32.6&degC during the summer and 8.7 – 17.2&degC during the winter. Temperature has profound effects on metabolism and physiology of reptiles, and thermal conditions likely play an important role in the timing of seasonal behaviors of terrapins. We investigated the effects of temperature on activity of lactate dehydrogenase (LDH), pyruvate kinase (PK), citrate synthase (CS), and cytochrome c oxidase(CCO) in muscle tissue collected from terrapins during the summer and winter. Assays were conducted at 10, 20, 30, and 40&degC. Within the temperature range of 10 – 30&degC, Q10 values varied between 1.3 and 1.8 for all enzymes. Q10 values for the anaerobic enzymes (LDH and PK) were higher (2.9 – 5.6) when assayed between 30 – 40&degC. There was no significant effect of season on activity of anaerobic enzymes, but there was a significant effect of season on activity of aerobic enzymes (CS and CCO), with winter activity lower than summer activity when assayed at the same temperature. Results are interpreted in light of terrapin ecology and habitat utilization.