大蛤, Meretrix lusoria 의 酸素消費와 窒素排泄

Oxygen Consumption and Nitrogen Excretion of Hard Clam, Meretrix luxoria

The rates of filtration, retention, respiration and nitrogen excretion of a hard clam, Meretrix lusoria were measured at laboratory conditions. The weight-specific filtration, retention, oxygen consumption and nitrogen excretion rates were decreased with increase of body weight, and the ralationships were expressed by exponential equation, M/W = aW(1-b). The coefficients of regression lines were -0.5569 to -0.7517 for the filtration, -0.6185 to -0.7653 for the retention, -0.5938 to -1.0149 for the oxygen consumption and -0.3550 to -0.9894 for the nitrogen excretion rates. The rate of filtration with food concentration showed a similar pattern to that of retention, and the rates of oxygen consumption and nitrogen excretion showed a considerable difference with change of water tempterature. Most of the excreted nitrogen was in the form of ammonia, and the considerable amounts of amino-N was excreted. In general, the O:N ratios were decreased with increasing body weight. The patterns of oxygen consumption and nitrogen excretion by hard clam showed a circadian rhythms. The oxygen consumption increased from sunset to midnight and decresed from midnight to midday, and the nitrogen excretion increased in the afternoon. In the range of experimental temperature of 11 to 29°C. In the range of experimental salinity of 13 to 33‰, the oxygen consumption showed the highest at 23‰, but the nitrogen excretion rate were decreased with decreasing salinity. When starved, the oxygen consumption and nitrogen excretion were decreased, and the decreasing rate in small size was remarkable compared with that of large size. Especially, the nitrogen excretion rate was signigicantly decreased.