Physiological responses of the common clownfish, Amphiprion ocellaris (Cuvier), to factors related to packaging and long-distance transport by air

Abstract

The physiological response of the common clownfish, A. ocellaris, to factors pertinent to air transportation conditions was studied in three stages: (i) determination of temperature effect and exposure process on oxygen consumption rates; (ii) elucidation of excretion trends of selected metabolites in simulated packaging experiments, and (iii) preliminary tolerance studies of some packaging parameters. Temperature significantly affected the metabolic rates of the clownfish. Q10 values were relatively constant in fish exposed to sudden changes in temperature (from 25°C to either 15, 20, 30 or 35°C). Those treated with gradual changes in temperature showed much greater increases in oxygen consumption at temperatures above 25°C. The temperature selected for subsequent experiments was 25°C. Dissolved oxygen levels of packaging water remained high throughout the 48-h period. Water [H+] and total dissolved and unionized CO2 concentrations changed most significantly during the initial 24 h and then levelled off by 48 h. Similarities in changes of concentrations between these imply close interaction between the measured variables. The total dissolved NH3 continued to increase with no signs of levelling off. The concentrations of unionized NH3 increased four-fold to 1.4 μM. The excretion of CO2 decreased linearly at a rate of 150 nmol/g per h while the excretion of NH3 increased at a rate of 97 nmol/g per h. A temperature range between 24 and 32°C was found to be necessary for survival of the fish with an optimal temperature of 27°C. Clownfish started to die when the pH of the seawater fell to 6.34 or total dissolved NH3 rose above 0.97 mM ([unionized NH3] = 38.35 μM). At 15°C, the fish started to die at 20 mm Hg which was twice the oxygen level at 20°C or above. © 1994.