Abstract
Diurnal fluctuations of seven hematological and 17 blood biochemical parameters were investigated in the winter solstice, spring equinox and summer solstice in captive Indo-Pacific bottlenose dolphins Tursiops aduncus. Blood sampling and feeding were conducted in three hour intervals for 24 h from four adult healthy males (estimated age; 36 to 39 years) kept in natural environmental conditions. HT, BUN, UA, TG, HGB, RBC, WBC, T-CHO, ALP and K showed diurnal rhythms, and four presented especially obvious diurnal rhythms with the lowest at 18:00 h in HT, and peaks during the evening or night in BUN, UA and TG (P<0.01). Acrophases of diurnal rhythms in these four parameters were not significantly different among the three seasons studied, and we suggested that these rhythms entrained environmental light-dark cycles and were controlled by endogenous circadian clock in the captive dolphins. Other parameters showed different three patterns: 1) irregular pulsed fluctuation (Eos, Alb, GOT, GPT, T-Bil, CPK, Na and Cl), 2) increase or decrease over time (Cre and Glu), and 3) no major changes throughout the day (Neut, Lym, TP and LDH).
