Effect of Two Levels of Temperature and Natural and Artificial Photoperiod on Growth and Metamorphosis of Bullfrog Tadpoles in an Intensive Rearing System

Abstract

AbstractThe effect of two levels of temperature and natural and artificial photoperiods on the growth and metamorphosis of tadpoles of the American bullfrog Rana catesbeiana were evaluated in an intensive‐rearing culture environment. Four groups of tadpoles at Gosner stage 24–25 were subjected for 50 d to four different treatments: (1) Tadpole culture with temperature control system (25.9 ± 0.34°C) and natural photoperiod of 12.25 h light : 11.75 h dark (treatment T), (2) an artificial photoperiod of 10 h light : 14 h dark using a white LED lamp and no temperature control system (18.7 ± 1°C) (treatment P), (3) the combination of temperature control system (26.01 ± 0.44°C) and an artificial photoperiod (10 h light : 14 h dark) (treatment T/P), and (4) culture with no temperature control system (21.87 ± 1.09°C) and a natural photoperiod (12.25 h light : 11.75 h dark) (treatment N/S). The experiment was performed under greenhouse conditions. Tadpoles in treatments T and T/P had the best growth performance as measured by total length (45.34 ± 1.89 mm [mean ± SE] for T/P, 44.72 ± 2.13 mm for T), head length (17.15 ± 0.67 mm for T/P, 18.34 ± 0.70 for T), and weight (1.00 ± 0.03 g for T/P, 1.14 ± 0.013 g for T). Tadpoles reared using white light LED lamps had reduced growth. The best results for tadpole metamorphosis were obtained in treatment T/P (25.9%), while treatment P presented the highest survival (36.2%). This experiment demonstrates that having temperature regulation is important to achieve better tadpole growth in intensive rearing systems. The regulation of both variables (T and P) is recommended for activating metamorphosis in the final phases of the tadpole development.