Routine oxygen consumption of Mugil cephalus, Liza dumerili and L. richardsoni at Different temperatures and salinities

Abstract

Oxygen consumption studies were undertaken with 3 mullet species to determine b, the exponent of w, as well as a, as indices of metabolic rate in the equation M=awbwhere M=metabolic rate, a=the intensity of metabolism, W=body weight, and b=the exponent of w. This was done under 5 experimental temperatures (13°, 18°, 23°, 28°, 33°C) for Mugil cephalus and Liza dumerili at 1 and at 35‰ S, and for L. richardsoni at 35‰S only. Mean b values were approximately 0.85. The a values depended on temperature, and increased according to Van't Hoff's law except for L. dumerili (1‰ S) and L. richardsoni (35‰ S) for a temperature increase from 23° to 28°C. It was found that handling had a profound influence on metabolic rate and led to considerably increased consumption rates during the first 8 h after introduction into the respiration chambers. Fasting in L. dumerili resulted in a total drop of 27% in oxygen consumption over a period of 6 days, of which 10% occurred over the first 24 h. Oxygen consumption displayed diurnal rhythms during the 6 day period, with lowest consumption rates at midday and midnight and highest just after sunrise and sunset.