9/18/2023 0 Comments Phototime nc aquarium![]() ![]() Studies of the behavior and movements of green turtles from other populations also indicate that turtles can remain active over a wide range of environmental temperatures. Based on sea surface temperature data and movement patterns of turtles,Seminoff ( 2000) suggested that the `inactivity threshold' for turtles at this site was 15☌ and that turtles may become torpid when temperatures drop below this threshold. Sonic tracking studies conducted by Seminoff( 2000) show that Eastern Pacific green turtles reside year-round at foraging pastures in the Gulf of California and can maintain activity during both summer and winter months. Although cold temperatures or changes in food availability may induce metabolic torpor in green turtles, this does not seem to be the common response to typical winter conditions. Felger et al.( 1976) observed Eastern Pacific green turtles ( Chelonia mydas agassizii) in the Gulf of California partially buried in the muddy substrate on the seafloor during winter when T W was less than 15☌ these turtles were lethargic and unresponsive when handled. ![]() There is evidence that green turtles from some populations may enter a state of torpor or dormancy during the winter, when environmental conditions are sub-optimal. Overall, our results suggest that green turtles have a relatively low thermal dependence of metabolic rate over the range of temperatures commonly experienced at tropical to subtropical latitudes, a trait which allows them to maintain activity year-round. Exposure to winter conditions resulted in a significant decrease in plasma thyroxine and plasma proteins and a significant increase in plasma creatine phosphokinase and hematocrit. Heart rate was 46-48%lower during the winter simulation compared with the summer simulation, and this difference was statistically significant. Citrate synthase, pyruvate kinase and lactate dehydrogenase had relatively low thermal dependence over the range of assay temperatures (15-30☌ Q 10=1.44-1.69). By contrast, activities of the glycolytic enzymes pyruvate kinase and lactate dehydrogenase were significantly higher in tissue collected during exposure to winter conditions compared with summer conditions. Exposure to winter conditions did result in a significant decrease in activity of the aerobic enzyme citrate synthase. Likewise, there was no statistically significant difference in breathing frequency between summer and winter simulations. There was a moderate 24-27% decrease in oxygen consumption during exposure to winter conditions compared with summer conditions, but this difference was not statistically significant. The activity level of turtles had a significant effect on oxygen consumption and breathing frequency but there was no significant change in activity level between the summer and winter simulations. We measured activity levels, oxygen consumption, metabolic enzyme activity,breathing frequency, heart rate and blood chemistry variables of juvenile green turtles exposed to a laboratory simulation of subtropical winter and summer temperatures (17-26☌) and photoperiod (10.25 h:13.75 h to 14 h:10 h light:dark). ![]()
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