Literaturdatenbank
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Leshem, A., Ar, A., & Ackerman, R. A. (1991). Growth, water, and energy metabolism of the soft-shelled turtle (trionyx triunguis) embryo: Effects of temperature. Physiological Zoology, 64(2), 568–594.
Added by: Admin (06 Jan 2014 18:22:56 UTC) |
| Resource type: Journal Article BibTeX citation key: Leshem1991 View all bibliographic details  |
Categories: General Keywords: Schildkröten - turtles + tortoises, Trionychidae, Trionyx triunguis, Zeitigung - incubation Creators: Ackerman, Ar, Leshem Collection: Physiological Zoology |
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| Abstract |
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Trionycidae The Nile soft-shelled turtle (Trionyx triunguis) lays about 40 18-g hard-shelled eggs in a nest cavity buried 20-40 cm deep in sand banks along rivers. The eggs exchange heat, water, and gases with the surrounding substrate during the 65-75-d incubation. Measurements to determine the effect of constant incubation temperature ( $T_{i}$ ) on embryonic growth and egg O₂ consumption ( $\dot{V}_{O_{2}}$ ) were conducted in the laboratory. Energy and water balances for the egg and embryo were constructed. Hatching success increases above 24° C and declines above 33° C Embryonic growth exhibited a sigmoid pattern and was significantly affected by $T_{i}$ Egg $\dot{V}_{O_{2}}$ increased during the first half of incubation, peaking at about 82% of incubation, and then decreased by about 30% during the remaining incubation time. Peak $\dot{V}_{O_{2}}$ was significantly affected by $T_{i}$ , but the final $\dot{V}_{O_{2}}$ just prior to pipping and hatching was not. Peak $\dot{V}_{O_{2}}$ was about 50-70 mL · d⁻¹ at standard temperature and pressure for dry gas (STPD), and final $\dot{V}_{O_{2}}$ was around 34-37 mL (STPD) · d⁻¹. The total O₂ consumption (1,283 mL · egg⁻¹) was not affected by $T_{i}$ . The O₂ cost of incubation was 72 mL (STPD) · g⁻¹ fresh egg and 108 mL (STPD) · g⁻¹ yolk-free hatchling. Within the range of $T_{i}$ tested, no significant differences were observed in yolk-free hatchling wet mass (11.8 g), water fraction (78%), or energy content and density (24 kJ · g⁻¹ dry mass). Nor were differences observed in residual yolk wet mass (0.4 g), its water fraction (51%), or its energy content and density (31 kJ · g⁻¹ dry mass). Approximately 21% of the water present in the egg is available for loss to the environment. The energy balance indicated that the gross production efficiency was around 70%, while total production efficiency was around 68%. The energy lost from metabolic inefficiency was around 28.4% of the total energy utilized during incubation. The patterns of growth, O₂ consumption rate, and allocation of energy of T. triunguis eggs and embryos were similar to those reported for avian species.
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