Acute and persistent effects of pre- and posthatching thermal environments on growth and metabolism in the red-eared slider turtle, Trachemys scripta elegans.
Many ectotherms possess the capacity to survive a wide range of thermal conditions. Long-term exposure to temperature can induce acclimational and/or organizational effects, and the developmental stage at which temperature exposure occurs may affect the type, degree, and persistence of these effects. We incubated red-eared slider turtle embryos at three different constant temperatures (T(inc); 26.5, 28.5, 30.5°C), then divided the resulting hatchlings between two water temperatures (T(water); 25, 30°C). We calculated growth rates to assess the short- and long-term effects of thermal experience on this metabolically costly process. We also measured resting metabolic rate (RMR) at three body temperatures (T(body;) 26.5, 28.5, 30.5°C) shortly after hatching and 6 months posthatching to characterize the degree and persistence of acclimation to T(inc) and T(water) . Hatchling RMRs were affected by T(body) and T(inc) , and fit a pattern consistent with positive but incomplete metabolic compensation to T(inc) . Average growth rates over the first 11 weeks posthatching were strongly affected by T(water) but only marginally influenced by T(inc) , and only at T(water) = 30°C. Six-month RMRs exhibited strong acclimation to T(water) consistent with positive metabolic compensation. However, within each T(water) treatment, RMR fit patterns indicative of inverse metabolic compensation to T(inc) , opposite of the pattern observed in hatchlings. Average growth rates calculated over 6 months continued to show a strong effect of T(water) , and the previously weak effect of T(inc) observed within the 30°C T(water) treatment became more pronounced. Our results suggest that metabolic compensation was reversible regardless of the life stage during which exposure occurred, and therefore is more appropriately considered acclimational than organizational.
Department of Biology, Missouri State University, Springfield, Missouri, USA. DayLigon@MissouriState.edu
Day B
DB
Ligon
Charles C
CC
Peterson
Matthew B
MB
Lovern
D000064:Acclimatization / Q000502:physiology*; D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D001481:Basal Metabolism; D005618:Fresh Water; D008018:Life Cycle Stages / Q000502:physiology*; D009825:Oklahoma; D013696:Temperature; D014426:Turtles / Q000254:growth & development* / Q000378:metabolism*