Oxygen consumption during embryonic development in red sea bream Pagrus major

Abstract: In our previous study, it has been elucidated that one of the causes of centrum defects in cultured red sea bream Pagrus major is oxygen deficiency during embryonic development. In the practical production of red sea bream seedlings, it is expectable that the condition of oxygen deficiency occurs during egg transportation and egg collection by dividing floating and sunken eggs. In this study, the ontogenetic change in oxygen consumption was investigated at 11 stages during the embryonic development at three different incubating temperatures of 16, 19, and 22 deg C for red sea bream. Based on these data, the change of dissolved oxygen concentration was simulated in the high density layer of developing eggs. The oxygen consumption rate of eggs was higher at the higher incubating temperature, that is, the oxygen consumption rate at 16 deg C, 19 deg C, and 22 deg C was 0.9*10E-4,1.3*1E-4, and 1.9*10E-4 micro l/ind/min at blastula stage, and 6.9*10E-4, 7.8 *10E-4, 11.0*10E-4 micro l/ind/min just before hatching, respectively. At all temperatures, the oxygen consumption rate increased almost linearly except for Kupffer's vesicle appear stage. Calculation from the obtained data suggested that the concentration of dissolved oxygen rapidly decreases in the pore space water in the high density layer of floating eggs. Therefore, it is recommended to control dissolved oxygen concentration during egg transportation and collection processes to prevent the deformity in cultured red sea bream, especially shortened body condition by centrum defects.